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Variation in menhaden fish meal characteristics and their effects on ruminal protein degradation as assessed by various techniques
ANIMAL FEED SCIENCE AND TECHNOLOGY
ELSEVIER
Animal Feed Science Technology 60 ( 1996) 13-27
Variation in menhaden fish meal characteristics and their effects on ruminal protein degradation as assessed by various techniques I.K. Yoon a, K.J. Lindquist a, D.D. Hongerholt a, M.D. Stern a, B.A. Crooker ay*,K.D. Short b aDepurtment ofAnimal Science, University of Minnesota, St. Paul, MN 55108, USA b Zapata Haynie Corporation, Hammond, LA 70404, USA
Received 10 November
1994; accepted
16 October
1995
Abstract Menhaden fish meal (FM) samples ,(n = 17) from five processing plants were used to evaluate effects of preparation on ruminal degradation of FM protein. The ability of routine industry measurements to predict ruminal protein degradation was also assessed. Industry measurements included fish quality (total volatile nitrogen, TVN), soluble addback (SOLADD), pepsin degradability and drying temperature (DRYT). Crude protein (CP) and fat contents of FM samples ranged from 65.0 to 75.4% and 9.1 to 12.7% of dry matter, respectively. Ruminal degradation of FM protein was determined by the in situ bag technique (BAGDEG, range of 27.4 to 56.4%). The ticin enzyme technique provided estimates of ruminal solubility (range of 6.0 to 33.9%) and ruminal degradation (range of 28.6 to 57.0%) of FM protein. Pearson correlation coefficients and probabilities for comparisons of BAGDEG with other estimates of degradability and FM preparation characteristics were determined. Equations to predict BAGDEG from routine industry measurements and from other estimates of degradation were developed. The amount of SOLADD explained 75% of the variation in BAGDEG and up to 81% of the variation was explained by including DRYT and CP. Prediction equations were evaluated using 10 additional menhaden FM samples. Coefficients of determination for comparisons of determined BAGDEG with predicted values from models containing up to 5 independent components ranged from 0.76 to 0.81 (P < 0.001). Results confirm that preparation methods alter ruminal degradation of FM protein. Data demonstrate a one variable model using SOLADD provides a simple, rapid and inexpensive way to predict ruminal degradation (BAGDEG) of menhaden FM protein and suggest measure-
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14
I.K. Yoon et al./Animal Feed Science Technology 60 (1996) 13-27
ments of ruminal solubility FM protein.
are the most closely correlated
predictors
of ruminal degradation
for
Keywords: Protein degradation; Fish meal
1. Introduction
Fish meal (FM) protein is considered to be of high quality and resistant to microbial degradation in the rumen (Clark et al., 1987; Hussein and Jordan, 1991). The amino acid profile of FM protein is rich in lysine and sulfur amino acids which are often limiting in diets for high producing dairy cows (Clark and Davis, 1980; Tamminga, 1982). However, ruminal degradation of FM protein varies considerably, ranging from about 30 to 70% (Mehrez et al., 1980). This variation is influenced by several factors including species of fish used as the starting material, quality of the raw material, proportion of solubles added back, drying conditions, differences in nutrient content due to processing methods and potential use of additional processing steps such as use of formaldehyde (Kaufmann and Lupping, 1982; Goldhor and Regenstein, 1987). Control of these factors is critical to maintain a uniform, quality FM product. A reliable methodology to evaluate the suitability of FM for ruminants would be beneficial. Degradation of dietary protein in the rumen is a principal factor affecting the quality of feeds for ruminants because it affects ruminal microbial protein synthesis and the total amount of protein supplied to the small intestine for absorption (Stokes et al., 1991; Clark et al., 1992). In vivo estimates of protein degradation (Stern et al., 1983; Van Vuuren et al., 1992) are labor intensive, time consuming and subject to considerable sources of variation (Stem and Satter, 1984) so alternative in vitro and in situ procedures are frequently used to estimate ruminal degradation of feed protein. These procedures include nitrogen solubility (Croaker et al., 1978; Stem and Satter, 19841, incubation with purified proteolytic enzymes (Poos-Floyd et al., 1985; Roe et al., 19911, ammonia release (Broderick, 1980), and the in situ bag technique (Broderick, 1980; Stem and Satter, 1984). Each of these methods has advantages and disadvantages relative to each other (Kaufmann and Lupping, 1982; Broderick et al., 1988). It is important to choose a procedure which provides accurate estimates of ruminal degradation. It is advantageous if the technique is simple, precise, and cost effective. The objectives of this study were to evaluate effects of FM characteristics on ruminal degradation of FM protein and to investigate the ability of common industry measurements of FM quality to predict ruminal degradation of FM protein.
2. Materials and methods 2.1. Fish meal samples Menhaden FM samples (n = 17) were obtained from five processing plants (A, B, C, D, and E) and differed in processing characteristics (Table 1). Total volatile nitrogen
I.K. Yoon et d/Animal Table I Characteristics
Feed Science Technology 60 (1996) 13-27
and nutrient content of fish meal samules a Nutrient content
Characteristics Sample b
TVN ’
DRYT ’
SOLADD
E-l A-2 A-3
0.08 0.08 0.09 0.11 0.08 0.12 0.12 0.12 0.13 0.16 0.13 0.46 0.15 0.21 0.20 0.14 0.21
2 2
2.1 0.1 1.5 13.6 2.1 18.3 16.2 21.0 6.8 23.5 21.1 24.7 26.3 24.1 22.2 25.1 30.5
A-5 D-4 D-3 D-l D-2 A-4 E-2 B-l C-l B-3 B-4 D-5 B-2 A-l
1 2 1 2
’
CP c
TOTPAT
66.6 75.4 69.9 70.8 13.4 69.4 65.7 68.0 68.2 67.9 68.2 65.0 70.0 69.4 69.9 70.3 67.1
9. I 11.7 12.0 11.8
’
9.2 10.8 10.6 11.6 12.2 9.4 9.2 10.4 12.1 10.8 9.3 9.9 12.4
a TVN = total volatile nitrogen; DRYT = drying temperature; SOLADD = soluble addback; CP = crude protein; TOTPAT = total fat. b Letter A-E = processing plants; number = sample identification within a processing plant. ’ Percentage of dry matter. d I = drying temperature < 60°C; 2 = drying temperature between 60 and 88°C.
(TVN) content of FM samples was measured (Association of Official Analytical Chemists, 1984) and used to assess quality of the raw fish materials. Relative freshness of the source of fish used to prepare FM or any solubles added back to FM can affect the TVN content of FM. A TVN content less than or equal to 0.15% of FM dry matter indicates that fresh material was used for FM preparation. A TVN content greater than 0.15% indicates use of stale material. Temperature of the FM sample (DRYT) leaving the dryer was measured to determine the extent of heating. Exit temperatures less than 60°C were considered gentle. Temperatures between 60 and 88°C were considered normal, and those greater than 88°C were considered harsh. The amount of fish solubles added back (SOLADD) to the dried FM was also recorded. Each sample was evaluated for nutrient content (Table 1) by Association of Official Analytical Chemists (1984) procedures prior to estimation of ruminal protein degradation. Dry matter (DM, 60°C oven) and nitrogen (Kjeldahl technique) contents were determined and crude protein calculated as N X 6.25. Chloroform was used to extract total fat (TOTFAT) from FM samples. 2.2. Ficin assay The ficin assay described by Poos-Floyd et al. (1985) and modified by Lindquist et al. (1989) was used to obtain estimates of ruminal solubility and degradation of FM
16
I.K. Yoon et al./Animal Feed Science Technology 60 (1996) 13-27
protein. Soluble and degradable protein content of FM samples was determined by incubating approximately 0.6 g of FM in each of four 50 ml round-bottom polypropylene centrifuge tubes with 15 ml of bicarbonate-phosphate buffer (0.16 M HCO,, 0.03 M PO,, pH 6.5). Control tubes containing 15 ml of buffer without FM were included in each assay. The tubes were capped with rubber stoppers equipped with release valves and were incubated for 2 h at 39°C in a shaking water bath. Tubes were swirled every 20 min by hand to minimize adhesion of FM particles on walls of centrifuge tubes. Incubations in two of the tubes were terminated by filtration through Whatman No. 541 filter paper. Solubility of CP (FICSOL) was calculated as the CP content of the filtrate divided by CP content of the sample. Ten ml of prewarmed phosphate buffer, containing 4.3 mg ml-’ of ficin, a proteolytic enzyme (Ficus glubrata, Sigma Chemical Co., St. Louis, MO, USA, Catalog #f-3266) extracted from fig tree latex, and 61 mg cysteine hydrochloride, were added to the two unfiltered suspensions of FM and ficin solubility buffer and to the unfiltered control tubes. Samples were incubated an additional hour at 39°C in a shaking water bath. Tubes were swirled by hand every 20 min. Incubations were terminated by filtration through Whatman No. 541 filter paper. Ruminal degradation of CP (FICDEG) was calculated as CP content of the filtrate divided by CP content of the sample. The insoluble degradable fraction of FM protein was calculated by subtracting FICSOL from FICDEG and reported as a percent of CP and as a percent of FICDEG. 2.3. In situ bag technique Dacron polyester with a mean pore size of 52 + 16 ,um (N. Erlanger Blumgart and Co., Inc., 1450 Broadway, New York, NY 10018, USA) was used to prepare 6 X 10 cm bags (Stem and Satter, 1984) with heat-sealed seams. Samples of FM were ground through a 2 mm screen and 0.5 g weighed into each of 14 polyester bags. The 14 bags of FM and 7 empty bags (used as blanks) were attached to a 60 cm string. All bags were immersed in lukewarm water for 15 min to remove readily soluble material. Two bags of FM and a blank bag were removed and used to estimate the soluble fraction (DEGTO) of FM protein. Remaining bags were suspended in the rumen of a cannulated, lactating Holstein cow consuming 20.2 kg DM d-l. The diet contained 37% maize silage, 21% alfalfa hay and 42% grain on a DM basis. The grain contained 48.5% ground corn, 20.2% soybean meal, 11.1% oats, 5.4% molasses, 5.3% animal fat, 1.6% distillers dried grains, 1.6% meat and bone meal, .9% urea, and 4.8% vitamins and minerals on a DM basis. Duplicate bags containing FM and a blank bag were removed from the rumen at 2, 4, 8, 12, 16 and 24 h after incubation. Bags were hand washed until rinse water became clear and dried in a 105°C forced air oven for 24 h. The procedure was repeated during the subsequent 24 h to provide 4 estimates of degradation of each FM sample at each incubation time. After correcting for nitrogen content of the blank bags, nitrogen content of the FM bags was assumed to represent undegraded FM nitrogen. Rate of CP degradation (kd) was calculated as the slope of the regression line that described the relationship between the natural log of the percent of FM protein remaining in the bags and time the bags were suspended in the rumen. An estimated rate of digesta flow (kp)
I.K. Yoon et al./Animd
Feed Science Technology
60 (1996)
13-27
I ‘7
from the rumen (6%/h), kd, and DEGTO were used to calculate extent (%I of ruminal degradation (BAGDEG) of FM protein in the rumen (Mathers and Miller, 198 1). BAGDEG = DEGTO + ( 100 - DEGTO) * (kd/( kd + kp)) BAGDEG was used as the standard to which all other estimates of ruminal degradation of FM protein were compared. The insoluble degradable fraction of FM protein was calculated by subtracting DEGTO from BAGDEG and reported as a percent of CP and as a percent of BAGDEG. 2.4. Pepsin digestion The large quantity of pepsin (0.2% solution) currently suggested by the Association of Official Analytical Chemists (1984) can completely digest proteins from typical animal sources within the 16 h digestion period (Johnston and Coon, 1979). These researchers concluded that when the quantity of pepsin-HCl solution was reduced, sensitivity of the test and digestibility differences among the animal proteins increased. Therefore, a 0.0002% pepsin solution was used in this study to determine the proportion of FM protein degraded by pepsin. Results were used as an indicator of post-ruminal availability of FM protein (Han and Parsons, 1991). 2.5. Development and validation of prediction equations
Multiple regression analyses were conducted to develop BAGDEG prediction equations from the original 17 FM samples. Two sets of prediction equations were developed; one utilized the routine industry measurements of quality (TVN, SOLADD and the pepsin degradable component), DRYT and nutrient content (CP and TOTFAT) of FM and the other used all of the variables measured in this study. Ten additional menhaden FM samples (Table 6) were used to evaluate the developed prediction equations. 2.6. Statistical analyses
Relationships among variables were assessed by correlation analyses. Simple and multiple regression procedures of SAS (1985) were utilized to develop equations to predict BAGDEG. The coefficient of determination (I?*> and Mallows’ criteria of reducing variance (Mallows, 1973) were used to determine the prediction equation with the best fit.
3. Results and discussion The BAGDEG of FM protein ranged from 27.4 to 56.4% (Table 2) and was within the range of previous observations (0rskov et al., 1971; Miller, 1973). The rate of degradation of FM protein varied between 0.0083 and 0.0165 hh’ (Table 2, Fig. l), was affected by FM characteristics, but was not highly correlated with BAGDEG (r = 0.09,
85.7 89.9 92.6 92.5 92.6 94.9 93.6 93.6 89.4 91.9 94.8 94. I 92.1 94.1 93.9 95.1 91.5
E-l A-2 A-3 A-5 D-4 D-3 D-l D-2 A-4 E-2 B-l C-l B-3 B-4 D-5 B-2 A-l
9.4 6.0 7.0 16.5 7.4 19.8 19.3 20.9 17.3 25.8 23.6 25.4 25.4 28.1 24.0 25.3 33.9
FICSOL ’
28.6 35.7 35.3 46.5 45.9 50.1 54.1 48.6 35.8 48.0 44.5 43.7 52.4 46.1 50.6 52.5 57.0
FICDEG ’ 19.2 29.7 28.3 30.0 38.5 30.3 34.8 27.7 18.5 22.2 20.9 18.3 27.0 18.0 26.6 27.2 23.1
FlCDlFF ’ 67.1 83.2 80.2 64.5 83.9 60.5 64.3 57.0 51.7 46.3 47.0 41.9 51.5 39.0 52.6 51.8 40.5
FICDPER d 0.0095 0.0104 0.0120 0.0113 0.0164 0.0113 0.0126 0.0113 0.0165 0.0109 0.0083 0.0088 0.0105 0.0094 0.0115 0.0113 0.0155
DEGRATE e 15.9 17.4 13.7 21.0 17.1 23.4 23.0 28.1 23.9 30.2 34.0 37.4 36.0 38.4 38.0 40.1 45.2
DEGTO ’ 27.4 29.6 28.0 33.5 34.9 35.5 36.4 39.5 40.3 40.9 42.0 45.4 45.6 46.3 48.2 49.6 56.4
BAGDEG ’ 11.5 12.2 14.3 12.5 17.8 12.1 13.4 11.4 16.4 10.7 8.0 8.0 9.6 7.9 10.2 9.5 11.2
BAGDIFF ’
42.0 41.2 51.1 37.3 51.0 34.1 36.8 28.9 40.7 26.2 19.0 17.6 21.1 17.1 21.2 19.2 19.9
BAGDPER ’
a PDEG = pepsin degradation; FICSOL = solubility in bicarbonate-phosphate buffer; FICDEG = kin degradation; FICDIFF = FICDEG-FICSOL, insoluble ruminal degradable protein; FICDPER = (FICDIFF)x lOO/FICDEG; DEGRATE = in situ estimate of degradation rate; DEGM = in situ bag, zero time solubility; BAGDEG = in situ bag estimate of ruminal degradation; BAGDIFF = BAGDEG-DEGTO, insoluble ruminal degradable protein; BAGDPER = (BAGDIFF) x lOO/BAGDEG. b Letter A-E = processing plants; number = sample identification within a processing plant. ’ Percentage of crude protein. d Insoluble as a percentage of FICDEG. e Fractional disappearance rate, h- ’. f Insoluble as a percentage of BAGDEG.
PDEG =
Sample b
Estimates of protein degradation
Table 2 Estimates of protein degradation of fish meal samples as assessed by various methods a
I.K. Yom et ul./Animnl
0
Feed Science Technology 60 (1996) 13-27
5
10
15
20
25
Time in rumen (h) Fig. I. Variation in rate of degradation of fish meal protein in the rumen. The most (W, 0.0165 h(0, 0.0083 h- ’) rapid rates of degradation of FM protein used in this study are plotted.
’) and least
P = 0.73). However, rate of degradation was positively correlated (r = 0.8 1, P = 0.0001) with the insoluble degradable fraction of FM protein (Table 3). Of the FM characteristics evaluated, SOLADD was most closely related (r = 0.869, P = 0.0001) to changes in ruminal protein degradation (Table 3). All estimates of protein solubility (SOLADD, FICSOL and DEGTO) were highly correlated with each other (r> 0.92, P < 0.0001) and with BAGDEG (r> 0.86, P < 0.0001). DEGTO provided the most reliable estimate of BAGDEG (Fig. 2). These results suggest that estimates of protein solubility provide reasonable estimates of FM protein degradation. Although protein solubility is not always a good predictor of the extent of ruminal degradation across a variety of feed components, several studies have demonstrated that estimates of protein solubility can frequently provide a reasonable estimate of ruminal degradation within a feedstuff (Beever et al., 1976; Laycock and Miller, 198 1). This observation is consistent with results in the current study. However, additional characteristics or inclusion of samples with characteristics that are outside the range of samples used in this study may alter the relationship between solubility and degradation. Owens and Bergen (1983) demonstrated that diet type and feeding conditions affect degradation of feeds and that these factors can compromise the ability of solubility measurements to predict ruminal degradation. In addition to being highly correlated with BAGDEG, solubility (DEGTO) of FM protein also accounted for a large proportion (69.2 + .l%> of BAGDEG. The degradable fraction of several animal by-product protein sources that are considered to be resistant to ruminal degradation can be composed of substantial amounts of soluble proteins. For example, soluble protein represented 50-80% of the degradable protein in FM, meat and bone meal, and hydrolyzed feather meal (Calsamiglia et al., 1995). Soluble protein (DEGTO) represented 49-83% of degradable protein in the 17 FM samples used in the present study. This large soluble protein component contributes to the ability of protein solubility estimates to predict degradation of FM protein. In contrast, the insoluble degradable fraction of FM protein varied little (range of 7.9 to 17.8% with a mean of 11.6 i 2.8% of CP) and was not highly correlated with other
l.oca
l.cal
0.907
0.750
0.898
0.585
0.510
0.037
0.790
0.0002
- 0.306
0.232
- 0.306
0.233
- 0.645
0.005
0.220
0.395
- 0.526
0.030
0.005
- 0.648
0.017
= drying
c P value.
BAGDIFF
DRYT
= BAGDEG
as a percentage
temperature:
0.135
0.0001
solubility; BAGDEG = bag degradation: 0 Correlation coefficient.
nitrogen:
FICDIFF
0.378
- 0.923
0.330
0.196
0.001
- FICSOL
degradation:
0.413
-0.213
0.473
- 0.187
0.393
0.017
-0.571
0.22 I
0.571
- 0.710
0.188
0.920
0.0001
0.236
0.362
0.634
0.006
0.254
- 0.336
0.360
0.933
0.252
- 0.293
0.545
- 0.237
- 0.022
- 0.294
0.0001
0.158
0.0001
0.869
0.610
0.009
- 0.867
-0.341
0.181
0.003
- 0.667
I.000 0.000
Estimates
- DEGTO
of CP;
of CP: BAGDPER
FIC-
TOTFAT = BAGDEG
nCD-
DE-
0.000 I
0.889
0.002
- DEGTO
= pepsin DEGRATE as a percentage
of FICDEG;
0.075
0.443
degradation of BACDEG.
= bag
rate:
zero
FICDEG
0.000
I.000
= bag
solubility;
0.0001
0.000 0.871
I .ooo
BAGDPER
BAGDIFF
DEGTO
= ficin
0.0001
0.041 - 0.842
- 0.501
0.000
I.000
DEG
BAG-
FICSOL
o.cQo I
- 0.944
0.002
- 0.698
O.wol
0.970
0.000
I .OOo
DEGTO
degradation:
0.000 I
0.807
0.727 0.687
0.092 0.0001
0.559
- 0.153
0.000
I .ooo
GRATE
0.817
0.0001
0.871
0.372
0.231
0.000
I .ooo
PER
= total fat: PDEG
0.038
0.507
0.022
0.55 I
0.194
- 0.332
0.085
- 0.43 I
0.145
0.369
0.002
0.697
0.000
I ,000
DIFF
as a percentage
0.017 protein:
- FICSOL
CP = crude
0.0001
- 0.571
0.300
0.004 -0.911
- 0.267
- 0.655
0.002
0.705
0.004
0.659
0.580
0.145
0.068
- 0.453
0.226
0.309
0.000
1.000
DEG
FlC-
degmdation
0.000 I
0.909
0.0001
0.938
0.61 I
- 0.133
0.0001
- 0.938
0.079
- 0.437
0.001
0.720
0.000
I .ow
FICSOL
of protein
= FICDEG
as a percentage
FICDPER
addback:
0.054
- 0.474
0.170
- 0.349
0.079
0.438
0.063
0.461
0.490
-0.180
0.228
- 0.308
0.350
0.242
0.003
0.674
0.063
0.461
0.000
I.000
PDEG
= soluble
0.759
0.080
0.542
0.159
0.826
0.058
0.992
0.003
0.289
0.273
0.980
0.006
0.936
0.021
0.774
0.075
0.832
0.056
0.704
- 0.100
SOLADD
0.038
0.0001
0.485
0.012
-0.143
- 0.507
0.971
0.182
0.592
0.943
0.017
0.052
0.191
-0.019
0.572
- 0.478
0.333
0.701
0.101
0.03 I
- 0.084
- 0.034
FAT
TOT-
content
.ooo
0.069
0.525
I
0.000
- 0.451
- 0.166
O.COO
Nutrient
CP
0.05 I
0.905
0.016
SOLADD
- 0.48 I
0.03 I
0.575
l.ocQ
O.CGl
0.446
0.073
DRYT
characteristics
= FICDEG
ficin
h
o.ccoc
a TVN = total volatile
BAGDPER
BAGDIFF
BAGDEG
DEGTO
DEGRATE
FICDPER
FICDIFF
FICDEG
FICSOL
PDEG
TOTFAT
CP
SOLADD
DRYT
TVN
TVN
Processing
Table 3 Pearson correlation coefficients and P values a
= time
I? u
I.K. Yoon et al./Animal Feed Science Technology 60 (1996) 13-27
21
(a)
20 ’ 10
I
I
20
30
40
50
DEGTO (%) (b)
FICSOL
(%)
20
SOLADD
(%)
Fig. 2. Relationships between mminal degradation (BAGDEG) and protein solubility measurements (DEGTO, FICSOL, and SOLADD) of fish meal protein. BAGDEG = estimate of protein degradation obtained from the in situ bag technique; DEGTO = estimate of protein solubility obtained by immersing bags with fish meal sample in lukewarm water for 15 min (plot a); FICSOL = sohtbility of fish meal protein iu bicarbonate-phosphate buffer (plot b); SOLADD = amount of fish solubles added back to the dried fish meal (plot c).
22
I.K. Yoon et al./Animal Feed Science Technology 60 (1996) 13-27
measurements except estimates of solubility and rate of degradation (Table 3). The insoluble degradable fraction also represented a small proportion (range of 12.1 to 21.6% with a mean of 16.4 + 3.1%) of the total insoluble fraction (lOO-DEGTO). Thus, insoluble FM proteins are quite resistant to ruminal degradation. Estimates of post-ruminal degradation obtained from incubation of the FM samples with pepsin were within a narrow range c&7-95.1%, 92.5 + 2.4% of CP) and were not correlated (r = 0.44, P = 0.08) with estimates of ruminal degradation. This observation suggests that FM characteristics evaluated in this study have little affect on post-ruminal availability of FM protein or pepsin digestion is not a sensitive technique to detect differences in post-ruminal availability of FM protein. Unpublished data (Yoon and Calsamiglia) from a three-step in vitro procedure to evaluate post-ruminal protein availability (Calsamiglia et al., 1995) confirms the high post-ruminal degradability of the insoluble portion of FM protein. Chen et al. (1987) demonstrated that drying temperature affects the proportion of feed protein susceptible to degradation in the rumen. Heat increased formation of disulfide bonds from oxidation of sulfhydryl groups (Opstvedt et al., 1984) and disulfide bond formation from cysteine and cystine increased in a linear manner when drying temperature increased from 50 to 115°C (Opstvedt et al., 1984). Disulfide bridges greatly reduce the rate of ruminal proteolysis of soluble and insoluble proteins (Mahadevan et al., 1980). The narrow range of DRYT and lack of harsh (> 88°C) temperatures used to dry the FM samples in the current study contributed to the lack of a relationship between DRYT and BAGDEG (r = 0.22, P = 0.39). Eleven of the FM samples were prepared from fresh material (TVN < 0.15%, Table 1). A positive linear relationship (r = 0.91, P = 0.0001) was detected between TVN and BAGDEG when TVN was less than 0.22% (Fig. 3). As TVN content exceeded 0.22%, BAGDEG decreased and the relationship became quadratic (r = 0.87, P = 0.0001). In agreement with previous studies (Mehrez et al., 1980; Goldhor and Regenstein, 19871, these results suggest quality of the starting material will affect ruminal degradation. The reduced ruminal degradability of FM samples with a TVN content greater than .22% is not due to a reduction in the soluble CP content of the FM samples or the amount of SOLADD (Tables 1 and 2), but is associated with a reduced degradation of the insoluble fraction. However, other factors must contribute to the reduction in ruminal degradability of FM protein. Ruminal degradation of the insoluble fraction of sample B-l also is also slow (Table 2) but this sample has a TVN content of .13%. Samples B-4 and C-l have TVN contents exceeding 0.22% and both were dried at normal (60-88°C) rather than gentle ( < 60°C) drying temperatures. A combination of increased TVN and DRYT might be responsible for the reduced BAGDEG observed with samples B-4 and C-l. The CP (65.0-75.4% of DM) and TOTFAT (9.1-12.7% of DM) contents varied little among the FM samples (Table 1). Neither CP (r = - 0.29, P = 0.25) nor TOTFAT (r = 0.06, P = 0.83) content of the FM samples were correlated with BAGDEG. These results suggest that minor fluctuations in CP and TOTFAT content of FM have little effect on ruminal degradation of FM protein. The ficin technique generally provided reliable estimates (FICSOL, FICDEG) of BAGDEG. It is interesting to note that the relationship between FICSOL and BAGDEG
I.K. Yoon et al./Animal 60
Feed Science Technology 60 (1996) 13-27
23
,
0.00
0.10
0.20
0.30
0.40
0.50
WN (%) Fig. 3. Relationship between ruminal degradation (BAGDEG) and total volatile nitrogen (TVN) of fish meal. Linear (Y,, 0) and quadratic (Yo, ?? ) relationships are presented. The linear relationship does not include fish meal samples (W) with a TVN content > 0.22% of DM.
was stronger than that between FICDEG and BAGDEG (r = 0.91, P < 0.0001 vs. r = 0.7 1, P = 0.002). The insoluble degradable fraction of FM protein estimated by ficin technique (FICDEG-FICSOL) was not highly correlated with any other measurements (Table 3). Best fit simple and multiple regression analyses were conducted to develop equations to predict BAGDEG (Tables 4 and 5). When only routine industry measurements were utilized, SOLADD alone explained 75% of the observed variation (Table 4). Up to 81% of the variation was explained when SOLADD, DRYT and CP were included in the prediction equation. These results indicate routine industry measurements can not provide exact values but can provide reasonable estimates of ruminal degradation of FM protein.
Table 4 Best fit simple and multiple regression equations to predict in situ estimates degradation of fish meal protein using routine industry measurements a
(BAGDEG)
of ruminal
Equation b
CP c
R2
Prediction equations
1 2 3 4
0.29 0.25 1.09 3.04
0.754 0.792 0.813 0.814
5
5.00
0.815
28.54+0.7OfSOLADD) 24.13 + 0.69(SOLADD) + 3.05(DRYT) - 13.30 + 0.75(SOLADD) + 3.45cDRYT) + 0.52(CP) _ 14.59 + 0.75cSOLADD) + 3.48cDRYT) + 0.5 l(CP) + 0.20(TOTFAT) - 26.55 + 0.72(SOLADD) + 3.8l(DRYT) + 0.47(CP) + 0.25cTOTFAT) + 0.1 S(PDEG)
a Coefficients obtained from Maximum R square procedure of SAS. b SOLADD = soluble addback; DRYT = drying temperature; CP = crude protein; TOTFAT = total fat; PDEG = pepsin degradation. ’ Mallows’ ”goodness of tit” statistic based on total squared error.
24
I.K. Yoon et al./Animal Feed Science Technology 60 (1996) 13-27
Table 5 Best tit simple and multiple regression equations to predict in situ estimates (BAGDEG) of ruminal degradation of fish meal protein using all the measured variables a Equation b
CP c
R2
Prediction equations
1
2 3
157.4 18.7 15.8
0.872 0.978 0.981
4
13.2
0.985
5
6.5
0.991
22.33 + O.B2(MEANSOL) b 41.11+ I~~!XDEGRATE)-0.76(BAGDPER) 38.32+2015(DEGRATE)-0.86(BAGDPER)+ O.OI(FICDPER) 35.29 + 2046(DEGRATE)-0.85(BAGDPER) + 0.1O(FICDPER) + 6.96(TVN) 17.83 + 1823cDEGRATE)- 0.56(BAGDPER) + 0.26@ICDPER)- 0.3l@ICDEG) + 0.80(MEANSOL)
a Coefficients obtained from Maximum R square procedure of SAS. b MEANSOL = mean of the three estimates of protein solubility (SOLADD, FICSOL, and DEGTO); DEGRATE = in situ estimate of degradation rate; BAGDPER = insoluble degradable fraction as a percentage of BAGDEG; FICDPER = insoluble degradable fraction as a percentage of FICDEG; TVN = total volatile nitrogen; FICDEG = ficin degradation. ’ Mallows’ “goodness of fit” statistic based on total squared error.
Because all estimates of protein solubility (SOLADD, FICSOL and DEGTO) were highly correlated with BAGDEG (Fig. 2) and were highly correlated with each other (Table 3), a mean of the three estimates (MEANSOL) was used when prediction equations were developed from all measured variables. Solubility again accounted for a major proportion (87%) of the variation in BAGDEG (Table 5). When all measured variables were considered, a five component equation provided the best fit (maximum coefficient of determination (I?*> and Mallows’ criteria) and accounted for 99% of the variation in BAGDEG.
Table 6 Characteristics and nutrient content of fish meal samples used for validation of prediction equations a Nutrient content
Characteristics Sample
I 2 3 4 5 6 7 8 9 10
TVN b
DRYT ’
SOLADD b
CP b
TOTFAT b
0.17 0.19 0.13 0.16 0.18 0.08 0.10 0.07 0.06 0.09
2 2 1
21.2 17.1 13.7 13.7 16.3 1.3 0.0 3.0
68.0 69.8 70.5 69.6 69.1 68.4 71.0 70.0 70.7 67.8
10.3 9.9 9.6 9.8 10.6 8.7 7.9 6.1 6.8 6.3
1 1
1 1
1 1 2
0.0 1.2
a TVN = total volatile nitrogen; DRYT = drying temperature; SOLADD = soluble addback; CP = crude protein; TOTFAT = total fat. b Percentage of dry matter. ’ 1 = drying temperature. < 60°C; 2 = drying temperature between 60 and 88°C.
I.K. Yom et al./Animal Table 7 Comparisons
of ruminal degradation
from prediction
equations
Feed Science Technology 60 (1996) 13-27
of fish meal (FM) protein estimated
25
from in situ procedure
or calculated
a,b
FM
BAGDEGe
BAGDEGpl
BAGDEGp2
BAGDEGp3
BAGDEGp4
BAGDEGp5
I 2 3 4 5 6 7 8 9 10
41.4 41.0 39.8 37.0 35.0 32.9 32.3 29.9 29.8 27.4
43.4 (2.0) 40.5 (- 0.5) 38.1 (- 1.7) 40.0 (3.0) 38.2 (3.2) 29.4(-3.5) 28.5 (- 3.8) 30.6 (0.7) 28.5 t - 1.3) 29.3 (1.9)
44.9 (3.5) 42.0 ( 1.O) 36.6 (- 3.2) 38.4 (1.4) 36.7 (1.7) 28.0 (- 4.9) 272-5.1) 29.2 (- 0.7) 27.2 (- 2.6) 3 1.O (3.6)
44.9 (3.5) 42.7 (1.7) 37.0 (- 2.8) 38.3 (1.3) 36.6 (1.6) 26.7 (- 6.2) 27.1 (-5.2) 28.8(1.1) 26.9 (- 2.9) 29.7 (2.3)
45.0 42.8 37.0 38.5 36.6 26.5 26.7 28.0 26.3 29.1
42.1 (0.7) 40.0 ( - 1.O) 34.2 (- 5.6) 35.6 (- 1.4) 33.9(1.1) 24.2 (- 8.7) 24.9 (- 7.4) 26.0 (- 3.9) 24.4 (- 5.5) 27.3 (- 0.2)
Mean
34.7
346-0.1)
34.1 ( - 0.6)
33.9 (- 0.8)
33.6(-
(3.6) (1.8) (- 2.8) (1.5) (1.6) (- 6.4) (- 5.6) ( - 1.9) (- 3.5) (1.7) 1.1)
31.3 (-3.4)
a BAGDEGe = estimation of BAGDEG by in situ procedure; BAGDEGpl = calculated BAGDEG from prediction Eq. (1); BAGDEGp2 = calculated BAGDEG from prediction Eq. (2); BAGDEGp3 = calculated BAGDEG from prediction Eq. (3); BAGDEGp4 = calculated BAGDEG from prediction Eq. (4); BAGDEGp5 = calculated BAGDEG from prediction Eq. (5). F’rediction equations are presented in Table 5. b Numbers in parenthesis represent the deviation from the estimated values.
Prediction equations developed from all measured variables (Table 5) demonstrate in situ measurements of rate of degradation and the proportion of degradable protein that is insoluble explain most of the variation in BAGDEG. Conducting the in situ measurements eliminates the need to predict BAGDEG. Thus, we did not attempt to evaluate the prediction equations listed in Table 5. Ten additional FM samples (Table 6) were used to determine if the prediction equations (Table 4) developed from routine industry measures provide reliable estimates of ruminal protein degradation. Estimates of BAGDEG were calculated from the developed equations and compared (Table 7) to BAGDEG values obtained from the in situ technique. Coefficients of determination and probabilities for comparisons of determined BAGDEG with predicted values from equations 1, 2, 3, 4 and 5 were R2 = 0.81, P = 0.0004; R* = 0.76, P = 0.001; R* = 0.79, P = 0.0006; R* = 0.80, P = 0.0005; R* = 0.79, P = 0.0006, respectively. Results demonstrate the one variable equation using SOLADD is highly correlated with BAGDEG measurements and provides a simple, rapid and inexpensive way to predict ruminal degradation of menhaden FM protein.
4. Conclusions Results confirm that FM characteristics affect the extent of degradation of FM protein in the rumen. Degradation of FM protein from different processing plants can be predicted by estimates of protein solubility. However, inclusion of estimates of degradation (e.g., degradation rate, insoluble degradable fraction of protein, etc.) will improve the ability to accurately predict total degradation. The fish meal industry can utilize
26
I.K. Yoon et al./Animal Feed Science Technology 60 (1996) 13-27
routine processing characteristics (SOLADD and DRYT) or soluble protein measurements to predict ruminal degradation of their products. These simple, rapid and inexpensive measurements can be used to obtain reliable estimates of ruminal degradation of FM protein.
Acknowledgements Published as paper no. 22,071 of the scientific journal series of the Minnesota Agricultural Experiment Station on research conducted under project nos. 16-045 and 16-048 supported by the College of Agriculture.
References Association of Official Analytical Chemists, 1984. Official methods of analysis. 14th edn., AOAC, Washington, DC. Beever, D.E., Thomson, D.J. and Cammell, S.B., 1976. The digestion of frozen and dried grass by sheep. J. Agric. Sci. (Camb.), 86: 443-452. Broderick, G.A., 1980. Estimation of protein degradation using in situ and in vitro methods. In: F. N. Owens (Editor), Protein Requirements for Cattle: Symposium. Nov. 19-21, at Oklahoma State University, Stillwater, OK, pp. 72-80. Broderick, G.A., Wallace, R.J., 0rskov, E.R. and Hansen, L., 1988. Comparison of estimates of ruminal protein degradation by in vitro and in situ methods. J. Anim. Sci., 66: 1739-1745. Calsamiglia, S., Stem, M.D. and Firkins, J.L. 1995. Effects of protein source on nitrogen metabolism in continuous culture and intestinal digestion in vitro. J. Anim. Sci. 73: 1819-1827. Chen, Cl., Sniffen, C.J. and Russell, J.B., 1987. Concentration and estimated flow of peptides from the rumen of dairy cattle: effects of protein quality, protein solubility and feeding frequency. J. Dairy Sci., 70: 983-992. Clark, J.H. and Davis, C.L., 1980. Some aspects of feeding high producing dairy cows. J. Dairy Sci., 63: 873-885. Clark, J.H., Murphy, M.R. and Crooker, B.A., 1987. Supplying the protein needs of dairy cattle from by-product feeds. J. Dairy Sci., 70: 1092-l 109. Clark, J.H., Klusmeyer, T.H. and Cameron, M.R., 1992. Microbial protein synthesis and flows of nitrogen fractions to the duodenum of dairy cows. J. Dairy Sci., 75: 2304-2323. Crooker, B.A., Sniffen, C.J., Hoover, W.H. and Johnson, L.L., 1978. Solvents for soluble nitrogen measurements in feedstuffs. J. Dairy Sci., 61: 437-447. Goldhor, S. and Regenstein, J.M., 1987. Fish meal in livestock feeds: new fmdings. hoc. Cornell Nutr. Conf., Ithaca, NY, pp. 98- 105. Han, Y. and Parsons, C.M., 1991. Protein and amino acid quality of feather meals. Poultry Sci., 70: 812-822. Hussein, H.S. and Jordan, R.M., 1991. Fish meal as a protein supplement in ruminant diets: a review. J. Anim. Sci., 69: 2147-2156. Johnston, J. and Coon, C.N., 1979. The use of varying levels of pepsin for pepsin digestion studies with animal proteins. Poultry Sci., 58: 1271- 1273. Kaufmann, W. and Lupping, W., 1982. Protected proteins and protected amino acids for ruminants, In: E. L. Miller, 1. H. Pike and A. J. H. Van Es (Editors), Protein Contribution of Feedstuffs for Ruminants. Butterworths, London, pp. 36-75. Laycock, K.A. and Miller, E.L., 1981. Nitrogen solubility and protein degradability of commercially and laboratory prepared rapeseed and soya-bean meals. Proc. Nutr. Sot., 40: 103A (Abstr.). Lindquist, K.J., Crooker, B.A., Illg, DJ. and Stem, M.D., 1989. Evaluation of ticin assay for estimating ruminal degradation of dietary protein. J. Anim. Sci. 67(Suppl. 1): 496.
I.K. Yom et al./Animal Mahadevan,
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S., Erfle, J.D. and Sauer, F.D., 1980. Degradation
27
of soluble and insoluble protein by Bactrroides
umylophdus protease and by rumen microorganisms. J. Anim. Sci., 50: 723-728. Mallows. CL., 1973. Some comments on Cp. Technometrics., 15: 661-676. Mathers, J.C. and Miller, E.L., 1981. Quantitative studies of food protein degradation and the energetic efficiency of microbial protein synthesis in the rumen of sheep given chopped luceme and rolled barley. Br. J. Nun., 45: 587-604. Mehrez, A.Z., Brskov, E.R. and Opstvedt, J., 1980. Processing factors affecting degradability of fish meal in the tumen. J. Anim. Sci., 50: 737-744. Miller, E.L., 1973. Evaluation of foods as sources of nitrogen and ammo acids. Proc. Nutr. Sot., 32: 79-84. Opstvedt, J., Miller, R., Hardy, R.W. and Spinelli, J., 1984. Heat-induced changes in sulthydryl groups and disultide bonds in fish protein and their effect on protein and amino acid digestibility in rainbow trout. J. Agric. Food Chem., 32: 929-935. 0rskov, E.R.. Fraser, C. and McDonald, I., 1971. Digestion of concentrates in sheep. 2. The effect of urea or fish-meal supplementation of barley diets on the apparent digestion of protein, fat, starch and ash in the mmen, the small intestine and the large intestine, and calculation of volatile fatty acid production. Brit. J. Nutr., 25: 243-252. Owens, F.N. and Bergen, W.G., 1983. Nitrogen metabolism of ruminant animals: historical perspective current understanding and future implications. J. Anim. Sci., 57(Suppl. 2): 4988518. Poos-Floyd, M., Klopfenstein, T. and B&ton, R.A., 1985. Evaluation of laboratory techniques for predicting mminal protein degradation. J. Dairy Sci., 68: 829-839. Roe, M.B., Chase, L.E. and Sniffen, C.J., 1991. Comparison of in vitro techniques to the in situ technique for estimation of ruminal degradation of protein. J. Dairy Sci., 74: 1632-1640. Statistical Analysis Systems Limited Inc., 1985. SAS User’s Guide: Statistics, Version 5 edn., SAS Institute, Inc., Gary, NC, USA. Stem, M.D. and Satter, L.D., 1984. Evaluation of nitrogen solubility and the Dacron bag technique as methods for estimating protein degradation in the rumen. J. Anim. Sci., 58: 714-724. Stem, M.D., Rode, L.M., Prange, R.W., Stauffacher, R.H. and Satter, L.D., 1983. Ruminal protein degradation of corn gluten meal in lactating dairy cattle fitted with duodenal t-type cannulae. J. Anim. Sci., 56: 194-205. Stokes, S.R., Hoover, W.H., Miller, T.K. and Blauweikel, R., 1991. Ruminal digestion and microbial utilization of diets varying in type of carbohydrate and protein. J. Dairy Sci., 74: 871-88 I. Tamminga, S., 1982. Energy-protein relationships in ruminant feeding: similarities and differences between rumen fermentation and postruminal utilization. In: E. L. Miller, I. H. Pike and A. J. H. Van Es (Editors), Protein Contribution of Feedstuffs for Ruminants. Butterworths, London, pp. 4- 17. Van Vuuren, A.M., Krol-Kramer, F., Van Der Lee, R.A. and Corbijn, H., 1992. Protein digestion and intestinal amino acids in dairy cows fed fresh Lolium perenne with different nitrogen contents. J. Dairy Sci., 75: 2215-2225.
ELSEVIER
Animal Feed Science Technology 60 ( 1996) 13-27
Variation in menhaden fish meal characteristics and their effects on ruminal protein degradation as assessed by various techniques I.K. Yoon a, K.J. Lindquist a, D.D. Hongerholt a, M.D. Stern a, B.A. Crooker ay*,K.D. Short b aDepurtment ofAnimal Science, University of Minnesota, St. Paul, MN 55108, USA b Zapata Haynie Corporation, Hammond, LA 70404, USA
Received 10 November
1994; accepted
16 October
1995
Abstract Menhaden fish meal (FM) samples ,(n = 17) from five processing plants were used to evaluate effects of preparation on ruminal degradation of FM protein. The ability of routine industry measurements to predict ruminal protein degradation was also assessed. Industry measurements included fish quality (total volatile nitrogen, TVN), soluble addback (SOLADD), pepsin degradability and drying temperature (DRYT). Crude protein (CP) and fat contents of FM samples ranged from 65.0 to 75.4% and 9.1 to 12.7% of dry matter, respectively. Ruminal degradation of FM protein was determined by the in situ bag technique (BAGDEG, range of 27.4 to 56.4%). The ticin enzyme technique provided estimates of ruminal solubility (range of 6.0 to 33.9%) and ruminal degradation (range of 28.6 to 57.0%) of FM protein. Pearson correlation coefficients and probabilities for comparisons of BAGDEG with other estimates of degradability and FM preparation characteristics were determined. Equations to predict BAGDEG from routine industry measurements and from other estimates of degradation were developed. The amount of SOLADD explained 75% of the variation in BAGDEG and up to 81% of the variation was explained by including DRYT and CP. Prediction equations were evaluated using 10 additional menhaden FM samples. Coefficients of determination for comparisons of determined BAGDEG with predicted values from models containing up to 5 independent components ranged from 0.76 to 0.81 (P < 0.001). Results confirm that preparation methods alter ruminal degradation of FM protein. Data demonstrate a one variable model using SOLADD provides a simple, rapid and inexpensive way to predict ruminal degradation (BAGDEG) of menhaden FM protein and suggest measure-
* Corresponding author. [email protected]).
(Tel.:
(612)
625
3185;
Fax.:
0377.8401/96/$ IS.000 1996 Elsevier Science B.V. All rights reserved SsDlO377-8401(95)00921-3
(612)
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E-mail:
14
I.K. Yoon et al./Animal Feed Science Technology 60 (1996) 13-27
ments of ruminal solubility FM protein.
are the most closely correlated
predictors
of ruminal degradation
for
Keywords: Protein degradation; Fish meal
1. Introduction
Fish meal (FM) protein is considered to be of high quality and resistant to microbial degradation in the rumen (Clark et al., 1987; Hussein and Jordan, 1991). The amino acid profile of FM protein is rich in lysine and sulfur amino acids which are often limiting in diets for high producing dairy cows (Clark and Davis, 1980; Tamminga, 1982). However, ruminal degradation of FM protein varies considerably, ranging from about 30 to 70% (Mehrez et al., 1980). This variation is influenced by several factors including species of fish used as the starting material, quality of the raw material, proportion of solubles added back, drying conditions, differences in nutrient content due to processing methods and potential use of additional processing steps such as use of formaldehyde (Kaufmann and Lupping, 1982; Goldhor and Regenstein, 1987). Control of these factors is critical to maintain a uniform, quality FM product. A reliable methodology to evaluate the suitability of FM for ruminants would be beneficial. Degradation of dietary protein in the rumen is a principal factor affecting the quality of feeds for ruminants because it affects ruminal microbial protein synthesis and the total amount of protein supplied to the small intestine for absorption (Stokes et al., 1991; Clark et al., 1992). In vivo estimates of protein degradation (Stern et al., 1983; Van Vuuren et al., 1992) are labor intensive, time consuming and subject to considerable sources of variation (Stem and Satter, 1984) so alternative in vitro and in situ procedures are frequently used to estimate ruminal degradation of feed protein. These procedures include nitrogen solubility (Croaker et al., 1978; Stem and Satter, 19841, incubation with purified proteolytic enzymes (Poos-Floyd et al., 1985; Roe et al., 19911, ammonia release (Broderick, 1980), and the in situ bag technique (Broderick, 1980; Stem and Satter, 1984). Each of these methods has advantages and disadvantages relative to each other (Kaufmann and Lupping, 1982; Broderick et al., 1988). It is important to choose a procedure which provides accurate estimates of ruminal degradation. It is advantageous if the technique is simple, precise, and cost effective. The objectives of this study were to evaluate effects of FM characteristics on ruminal degradation of FM protein and to investigate the ability of common industry measurements of FM quality to predict ruminal degradation of FM protein.
2. Materials and methods 2.1. Fish meal samples Menhaden FM samples (n = 17) were obtained from five processing plants (A, B, C, D, and E) and differed in processing characteristics (Table 1). Total volatile nitrogen
I.K. Yoon et d/Animal Table I Characteristics
Feed Science Technology 60 (1996) 13-27
and nutrient content of fish meal samules a Nutrient content
Characteristics Sample b
TVN ’
DRYT ’
SOLADD
E-l A-2 A-3
0.08 0.08 0.09 0.11 0.08 0.12 0.12 0.12 0.13 0.16 0.13 0.46 0.15 0.21 0.20 0.14 0.21
2 2
2.1 0.1 1.5 13.6 2.1 18.3 16.2 21.0 6.8 23.5 21.1 24.7 26.3 24.1 22.2 25.1 30.5
A-5 D-4 D-3 D-l D-2 A-4 E-2 B-l C-l B-3 B-4 D-5 B-2 A-l
1 2 1 2
’
CP c
TOTPAT
66.6 75.4 69.9 70.8 13.4 69.4 65.7 68.0 68.2 67.9 68.2 65.0 70.0 69.4 69.9 70.3 67.1
9. I 11.7 12.0 11.8
’
9.2 10.8 10.6 11.6 12.2 9.4 9.2 10.4 12.1 10.8 9.3 9.9 12.4
a TVN = total volatile nitrogen; DRYT = drying temperature; SOLADD = soluble addback; CP = crude protein; TOTPAT = total fat. b Letter A-E = processing plants; number = sample identification within a processing plant. ’ Percentage of dry matter. d I = drying temperature < 60°C; 2 = drying temperature between 60 and 88°C.
(TVN) content of FM samples was measured (Association of Official Analytical Chemists, 1984) and used to assess quality of the raw fish materials. Relative freshness of the source of fish used to prepare FM or any solubles added back to FM can affect the TVN content of FM. A TVN content less than or equal to 0.15% of FM dry matter indicates that fresh material was used for FM preparation. A TVN content greater than 0.15% indicates use of stale material. Temperature of the FM sample (DRYT) leaving the dryer was measured to determine the extent of heating. Exit temperatures less than 60°C were considered gentle. Temperatures between 60 and 88°C were considered normal, and those greater than 88°C were considered harsh. The amount of fish solubles added back (SOLADD) to the dried FM was also recorded. Each sample was evaluated for nutrient content (Table 1) by Association of Official Analytical Chemists (1984) procedures prior to estimation of ruminal protein degradation. Dry matter (DM, 60°C oven) and nitrogen (Kjeldahl technique) contents were determined and crude protein calculated as N X 6.25. Chloroform was used to extract total fat (TOTFAT) from FM samples. 2.2. Ficin assay The ficin assay described by Poos-Floyd et al. (1985) and modified by Lindquist et al. (1989) was used to obtain estimates of ruminal solubility and degradation of FM
16
I.K. Yoon et al./Animal Feed Science Technology 60 (1996) 13-27
protein. Soluble and degradable protein content of FM samples was determined by incubating approximately 0.6 g of FM in each of four 50 ml round-bottom polypropylene centrifuge tubes with 15 ml of bicarbonate-phosphate buffer (0.16 M HCO,, 0.03 M PO,, pH 6.5). Control tubes containing 15 ml of buffer without FM were included in each assay. The tubes were capped with rubber stoppers equipped with release valves and were incubated for 2 h at 39°C in a shaking water bath. Tubes were swirled every 20 min by hand to minimize adhesion of FM particles on walls of centrifuge tubes. Incubations in two of the tubes were terminated by filtration through Whatman No. 541 filter paper. Solubility of CP (FICSOL) was calculated as the CP content of the filtrate divided by CP content of the sample. Ten ml of prewarmed phosphate buffer, containing 4.3 mg ml-’ of ficin, a proteolytic enzyme (Ficus glubrata, Sigma Chemical Co., St. Louis, MO, USA, Catalog #f-3266) extracted from fig tree latex, and 61 mg cysteine hydrochloride, were added to the two unfiltered suspensions of FM and ficin solubility buffer and to the unfiltered control tubes. Samples were incubated an additional hour at 39°C in a shaking water bath. Tubes were swirled by hand every 20 min. Incubations were terminated by filtration through Whatman No. 541 filter paper. Ruminal degradation of CP (FICDEG) was calculated as CP content of the filtrate divided by CP content of the sample. The insoluble degradable fraction of FM protein was calculated by subtracting FICSOL from FICDEG and reported as a percent of CP and as a percent of FICDEG. 2.3. In situ bag technique Dacron polyester with a mean pore size of 52 + 16 ,um (N. Erlanger Blumgart and Co., Inc., 1450 Broadway, New York, NY 10018, USA) was used to prepare 6 X 10 cm bags (Stem and Satter, 1984) with heat-sealed seams. Samples of FM were ground through a 2 mm screen and 0.5 g weighed into each of 14 polyester bags. The 14 bags of FM and 7 empty bags (used as blanks) were attached to a 60 cm string. All bags were immersed in lukewarm water for 15 min to remove readily soluble material. Two bags of FM and a blank bag were removed and used to estimate the soluble fraction (DEGTO) of FM protein. Remaining bags were suspended in the rumen of a cannulated, lactating Holstein cow consuming 20.2 kg DM d-l. The diet contained 37% maize silage, 21% alfalfa hay and 42% grain on a DM basis. The grain contained 48.5% ground corn, 20.2% soybean meal, 11.1% oats, 5.4% molasses, 5.3% animal fat, 1.6% distillers dried grains, 1.6% meat and bone meal, .9% urea, and 4.8% vitamins and minerals on a DM basis. Duplicate bags containing FM and a blank bag were removed from the rumen at 2, 4, 8, 12, 16 and 24 h after incubation. Bags were hand washed until rinse water became clear and dried in a 105°C forced air oven for 24 h. The procedure was repeated during the subsequent 24 h to provide 4 estimates of degradation of each FM sample at each incubation time. After correcting for nitrogen content of the blank bags, nitrogen content of the FM bags was assumed to represent undegraded FM nitrogen. Rate of CP degradation (kd) was calculated as the slope of the regression line that described the relationship between the natural log of the percent of FM protein remaining in the bags and time the bags were suspended in the rumen. An estimated rate of digesta flow (kp)
I.K. Yoon et al./Animd
Feed Science Technology
60 (1996)
13-27
I ‘7
from the rumen (6%/h), kd, and DEGTO were used to calculate extent (%I of ruminal degradation (BAGDEG) of FM protein in the rumen (Mathers and Miller, 198 1). BAGDEG = DEGTO + ( 100 - DEGTO) * (kd/( kd + kp)) BAGDEG was used as the standard to which all other estimates of ruminal degradation of FM protein were compared. The insoluble degradable fraction of FM protein was calculated by subtracting DEGTO from BAGDEG and reported as a percent of CP and as a percent of BAGDEG. 2.4. Pepsin digestion The large quantity of pepsin (0.2% solution) currently suggested by the Association of Official Analytical Chemists (1984) can completely digest proteins from typical animal sources within the 16 h digestion period (Johnston and Coon, 1979). These researchers concluded that when the quantity of pepsin-HCl solution was reduced, sensitivity of the test and digestibility differences among the animal proteins increased. Therefore, a 0.0002% pepsin solution was used in this study to determine the proportion of FM protein degraded by pepsin. Results were used as an indicator of post-ruminal availability of FM protein (Han and Parsons, 1991). 2.5. Development and validation of prediction equations
Multiple regression analyses were conducted to develop BAGDEG prediction equations from the original 17 FM samples. Two sets of prediction equations were developed; one utilized the routine industry measurements of quality (TVN, SOLADD and the pepsin degradable component), DRYT and nutrient content (CP and TOTFAT) of FM and the other used all of the variables measured in this study. Ten additional menhaden FM samples (Table 6) were used to evaluate the developed prediction equations. 2.6. Statistical analyses
Relationships among variables were assessed by correlation analyses. Simple and multiple regression procedures of SAS (1985) were utilized to develop equations to predict BAGDEG. The coefficient of determination (I?*> and Mallows’ criteria of reducing variance (Mallows, 1973) were used to determine the prediction equation with the best fit.
3. Results and discussion The BAGDEG of FM protein ranged from 27.4 to 56.4% (Table 2) and was within the range of previous observations (0rskov et al., 1971; Miller, 1973). The rate of degradation of FM protein varied between 0.0083 and 0.0165 hh’ (Table 2, Fig. l), was affected by FM characteristics, but was not highly correlated with BAGDEG (r = 0.09,
85.7 89.9 92.6 92.5 92.6 94.9 93.6 93.6 89.4 91.9 94.8 94. I 92.1 94.1 93.9 95.1 91.5
E-l A-2 A-3 A-5 D-4 D-3 D-l D-2 A-4 E-2 B-l C-l B-3 B-4 D-5 B-2 A-l
9.4 6.0 7.0 16.5 7.4 19.8 19.3 20.9 17.3 25.8 23.6 25.4 25.4 28.1 24.0 25.3 33.9
FICSOL ’
28.6 35.7 35.3 46.5 45.9 50.1 54.1 48.6 35.8 48.0 44.5 43.7 52.4 46.1 50.6 52.5 57.0
FICDEG ’ 19.2 29.7 28.3 30.0 38.5 30.3 34.8 27.7 18.5 22.2 20.9 18.3 27.0 18.0 26.6 27.2 23.1
FlCDlFF ’ 67.1 83.2 80.2 64.5 83.9 60.5 64.3 57.0 51.7 46.3 47.0 41.9 51.5 39.0 52.6 51.8 40.5
FICDPER d 0.0095 0.0104 0.0120 0.0113 0.0164 0.0113 0.0126 0.0113 0.0165 0.0109 0.0083 0.0088 0.0105 0.0094 0.0115 0.0113 0.0155
DEGRATE e 15.9 17.4 13.7 21.0 17.1 23.4 23.0 28.1 23.9 30.2 34.0 37.4 36.0 38.4 38.0 40.1 45.2
DEGTO ’ 27.4 29.6 28.0 33.5 34.9 35.5 36.4 39.5 40.3 40.9 42.0 45.4 45.6 46.3 48.2 49.6 56.4
BAGDEG ’ 11.5 12.2 14.3 12.5 17.8 12.1 13.4 11.4 16.4 10.7 8.0 8.0 9.6 7.9 10.2 9.5 11.2
BAGDIFF ’
42.0 41.2 51.1 37.3 51.0 34.1 36.8 28.9 40.7 26.2 19.0 17.6 21.1 17.1 21.2 19.2 19.9
BAGDPER ’
a PDEG = pepsin degradation; FICSOL = solubility in bicarbonate-phosphate buffer; FICDEG = kin degradation; FICDIFF = FICDEG-FICSOL, insoluble ruminal degradable protein; FICDPER = (FICDIFF)x lOO/FICDEG; DEGRATE = in situ estimate of degradation rate; DEGM = in situ bag, zero time solubility; BAGDEG = in situ bag estimate of ruminal degradation; BAGDIFF = BAGDEG-DEGTO, insoluble ruminal degradable protein; BAGDPER = (BAGDIFF) x lOO/BAGDEG. b Letter A-E = processing plants; number = sample identification within a processing plant. ’ Percentage of crude protein. d Insoluble as a percentage of FICDEG. e Fractional disappearance rate, h- ’. f Insoluble as a percentage of BAGDEG.
PDEG =
Sample b
Estimates of protein degradation
Table 2 Estimates of protein degradation of fish meal samples as assessed by various methods a
I.K. Yom et ul./Animnl
0
Feed Science Technology 60 (1996) 13-27
5
10
15
20
25
Time in rumen (h) Fig. I. Variation in rate of degradation of fish meal protein in the rumen. The most (W, 0.0165 h(0, 0.0083 h- ’) rapid rates of degradation of FM protein used in this study are plotted.
’) and least
P = 0.73). However, rate of degradation was positively correlated (r = 0.8 1, P = 0.0001) with the insoluble degradable fraction of FM protein (Table 3). Of the FM characteristics evaluated, SOLADD was most closely related (r = 0.869, P = 0.0001) to changes in ruminal protein degradation (Table 3). All estimates of protein solubility (SOLADD, FICSOL and DEGTO) were highly correlated with each other (r> 0.92, P < 0.0001) and with BAGDEG (r> 0.86, P < 0.0001). DEGTO provided the most reliable estimate of BAGDEG (Fig. 2). These results suggest that estimates of protein solubility provide reasonable estimates of FM protein degradation. Although protein solubility is not always a good predictor of the extent of ruminal degradation across a variety of feed components, several studies have demonstrated that estimates of protein solubility can frequently provide a reasonable estimate of ruminal degradation within a feedstuff (Beever et al., 1976; Laycock and Miller, 198 1). This observation is consistent with results in the current study. However, additional characteristics or inclusion of samples with characteristics that are outside the range of samples used in this study may alter the relationship between solubility and degradation. Owens and Bergen (1983) demonstrated that diet type and feeding conditions affect degradation of feeds and that these factors can compromise the ability of solubility measurements to predict ruminal degradation. In addition to being highly correlated with BAGDEG, solubility (DEGTO) of FM protein also accounted for a large proportion (69.2 + .l%> of BAGDEG. The degradable fraction of several animal by-product protein sources that are considered to be resistant to ruminal degradation can be composed of substantial amounts of soluble proteins. For example, soluble protein represented 50-80% of the degradable protein in FM, meat and bone meal, and hydrolyzed feather meal (Calsamiglia et al., 1995). Soluble protein (DEGTO) represented 49-83% of degradable protein in the 17 FM samples used in the present study. This large soluble protein component contributes to the ability of protein solubility estimates to predict degradation of FM protein. In contrast, the insoluble degradable fraction of FM protein varied little (range of 7.9 to 17.8% with a mean of 11.6 i 2.8% of CP) and was not highly correlated with other
l.oca
l.cal
0.907
0.750
0.898
0.585
0.510
0.037
0.790
0.0002
- 0.306
0.232
- 0.306
0.233
- 0.645
0.005
0.220
0.395
- 0.526
0.030
0.005
- 0.648
0.017
= drying
c P value.
BAGDIFF
DRYT
= BAGDEG
as a percentage
temperature:
0.135
0.0001
solubility; BAGDEG = bag degradation: 0 Correlation coefficient.
nitrogen:
FICDIFF
0.378
- 0.923
0.330
0.196
0.001
- FICSOL
degradation:
0.413
-0.213
0.473
- 0.187
0.393
0.017
-0.571
0.22 I
0.571
- 0.710
0.188
0.920
0.0001
0.236
0.362
0.634
0.006
0.254
- 0.336
0.360
0.933
0.252
- 0.293
0.545
- 0.237
- 0.022
- 0.294
0.0001
0.158
0.0001
0.869
0.610
0.009
- 0.867
-0.341
0.181
0.003
- 0.667
I.000 0.000
Estimates
- DEGTO
of CP;
of CP: BAGDPER
FIC-
TOTFAT = BAGDEG
nCD-
DE-
0.000 I
0.889
0.002
- DEGTO
= pepsin DEGRATE as a percentage
of FICDEG;
0.075
0.443
degradation of BACDEG.
= bag
rate:
zero
FICDEG
0.000
I.000
= bag
solubility;
0.0001
0.000 0.871
I .ooo
BAGDPER
BAGDIFF
DEGTO
= ficin
0.0001
0.041 - 0.842
- 0.501
0.000
I.000
DEG
BAG-
FICSOL
o.cQo I
- 0.944
0.002
- 0.698
O.wol
0.970
0.000
I .OOo
DEGTO
degradation:
0.000 I
0.807
0.727 0.687
0.092 0.0001
0.559
- 0.153
0.000
I .ooo
GRATE
0.817
0.0001
0.871
0.372
0.231
0.000
I .ooo
PER
= total fat: PDEG
0.038
0.507
0.022
0.55 I
0.194
- 0.332
0.085
- 0.43 I
0.145
0.369
0.002
0.697
0.000
I ,000
DIFF
as a percentage
0.017 protein:
- FICSOL
CP = crude
0.0001
- 0.571
0.300
0.004 -0.911
- 0.267
- 0.655
0.002
0.705
0.004
0.659
0.580
0.145
0.068
- 0.453
0.226
0.309
0.000
1.000
DEG
FlC-
degmdation
0.000 I
0.909
0.0001
0.938
0.61 I
- 0.133
0.0001
- 0.938
0.079
- 0.437
0.001
0.720
0.000
I .ow
FICSOL
of protein
= FICDEG
as a percentage
FICDPER
addback:
0.054
- 0.474
0.170
- 0.349
0.079
0.438
0.063
0.461
0.490
-0.180
0.228
- 0.308
0.350
0.242
0.003
0.674
0.063
0.461
0.000
I.000
PDEG
= soluble
0.759
0.080
0.542
0.159
0.826
0.058
0.992
0.003
0.289
0.273
0.980
0.006
0.936
0.021
0.774
0.075
0.832
0.056
0.704
- 0.100
SOLADD
0.038
0.0001
0.485
0.012
-0.143
- 0.507
0.971
0.182
0.592
0.943
0.017
0.052
0.191
-0.019
0.572
- 0.478
0.333
0.701
0.101
0.03 I
- 0.084
- 0.034
FAT
TOT-
content
.ooo
0.069
0.525
I
0.000
- 0.451
- 0.166
O.COO
Nutrient
CP
0.05 I
0.905
0.016
SOLADD
- 0.48 I
0.03 I
0.575
l.ocQ
O.CGl
0.446
0.073
DRYT
characteristics
= FICDEG
ficin
h
o.ccoc
a TVN = total volatile
BAGDPER
BAGDIFF
BAGDEG
DEGTO
DEGRATE
FICDPER
FICDIFF
FICDEG
FICSOL
PDEG
TOTFAT
CP
SOLADD
DRYT
TVN
TVN
Processing
Table 3 Pearson correlation coefficients and P values a
= time
I? u
I.K. Yoon et al./Animal Feed Science Technology 60 (1996) 13-27
21
(a)
20 ’ 10
I
I
20
30
40
50
DEGTO (%) (b)
FICSOL
(%)
20
SOLADD
(%)
Fig. 2. Relationships between mminal degradation (BAGDEG) and protein solubility measurements (DEGTO, FICSOL, and SOLADD) of fish meal protein. BAGDEG = estimate of protein degradation obtained from the in situ bag technique; DEGTO = estimate of protein solubility obtained by immersing bags with fish meal sample in lukewarm water for 15 min (plot a); FICSOL = sohtbility of fish meal protein iu bicarbonate-phosphate buffer (plot b); SOLADD = amount of fish solubles added back to the dried fish meal (plot c).
22
I.K. Yoon et al./Animal Feed Science Technology 60 (1996) 13-27
measurements except estimates of solubility and rate of degradation (Table 3). The insoluble degradable fraction also represented a small proportion (range of 12.1 to 21.6% with a mean of 16.4 + 3.1%) of the total insoluble fraction (lOO-DEGTO). Thus, insoluble FM proteins are quite resistant to ruminal degradation. Estimates of post-ruminal degradation obtained from incubation of the FM samples with pepsin were within a narrow range c&7-95.1%, 92.5 + 2.4% of CP) and were not correlated (r = 0.44, P = 0.08) with estimates of ruminal degradation. This observation suggests that FM characteristics evaluated in this study have little affect on post-ruminal availability of FM protein or pepsin digestion is not a sensitive technique to detect differences in post-ruminal availability of FM protein. Unpublished data (Yoon and Calsamiglia) from a three-step in vitro procedure to evaluate post-ruminal protein availability (Calsamiglia et al., 1995) confirms the high post-ruminal degradability of the insoluble portion of FM protein. Chen et al. (1987) demonstrated that drying temperature affects the proportion of feed protein susceptible to degradation in the rumen. Heat increased formation of disulfide bonds from oxidation of sulfhydryl groups (Opstvedt et al., 1984) and disulfide bond formation from cysteine and cystine increased in a linear manner when drying temperature increased from 50 to 115°C (Opstvedt et al., 1984). Disulfide bridges greatly reduce the rate of ruminal proteolysis of soluble and insoluble proteins (Mahadevan et al., 1980). The narrow range of DRYT and lack of harsh (> 88°C) temperatures used to dry the FM samples in the current study contributed to the lack of a relationship between DRYT and BAGDEG (r = 0.22, P = 0.39). Eleven of the FM samples were prepared from fresh material (TVN < 0.15%, Table 1). A positive linear relationship (r = 0.91, P = 0.0001) was detected between TVN and BAGDEG when TVN was less than 0.22% (Fig. 3). As TVN content exceeded 0.22%, BAGDEG decreased and the relationship became quadratic (r = 0.87, P = 0.0001). In agreement with previous studies (Mehrez et al., 1980; Goldhor and Regenstein, 19871, these results suggest quality of the starting material will affect ruminal degradation. The reduced ruminal degradability of FM samples with a TVN content greater than .22% is not due to a reduction in the soluble CP content of the FM samples or the amount of SOLADD (Tables 1 and 2), but is associated with a reduced degradation of the insoluble fraction. However, other factors must contribute to the reduction in ruminal degradability of FM protein. Ruminal degradation of the insoluble fraction of sample B-l also is also slow (Table 2) but this sample has a TVN content of .13%. Samples B-4 and C-l have TVN contents exceeding 0.22% and both were dried at normal (60-88°C) rather than gentle ( < 60°C) drying temperatures. A combination of increased TVN and DRYT might be responsible for the reduced BAGDEG observed with samples B-4 and C-l. The CP (65.0-75.4% of DM) and TOTFAT (9.1-12.7% of DM) contents varied little among the FM samples (Table 1). Neither CP (r = - 0.29, P = 0.25) nor TOTFAT (r = 0.06, P = 0.83) content of the FM samples were correlated with BAGDEG. These results suggest that minor fluctuations in CP and TOTFAT content of FM have little effect on ruminal degradation of FM protein. The ficin technique generally provided reliable estimates (FICSOL, FICDEG) of BAGDEG. It is interesting to note that the relationship between FICSOL and BAGDEG
I.K. Yoon et al./Animal 60
Feed Science Technology 60 (1996) 13-27
23
,
0.00
0.10
0.20
0.30
0.40
0.50
WN (%) Fig. 3. Relationship between ruminal degradation (BAGDEG) and total volatile nitrogen (TVN) of fish meal. Linear (Y,, 0) and quadratic (Yo, ?? ) relationships are presented. The linear relationship does not include fish meal samples (W) with a TVN content > 0.22% of DM.
was stronger than that between FICDEG and BAGDEG (r = 0.91, P < 0.0001 vs. r = 0.7 1, P = 0.002). The insoluble degradable fraction of FM protein estimated by ficin technique (FICDEG-FICSOL) was not highly correlated with any other measurements (Table 3). Best fit simple and multiple regression analyses were conducted to develop equations to predict BAGDEG (Tables 4 and 5). When only routine industry measurements were utilized, SOLADD alone explained 75% of the observed variation (Table 4). Up to 81% of the variation was explained when SOLADD, DRYT and CP were included in the prediction equation. These results indicate routine industry measurements can not provide exact values but can provide reasonable estimates of ruminal degradation of FM protein.
Table 4 Best fit simple and multiple regression equations to predict in situ estimates degradation of fish meal protein using routine industry measurements a
(BAGDEG)
of ruminal
Equation b
CP c
R2
Prediction equations
1 2 3 4
0.29 0.25 1.09 3.04
0.754 0.792 0.813 0.814
5
5.00
0.815
28.54+0.7OfSOLADD) 24.13 + 0.69(SOLADD) + 3.05(DRYT) - 13.30 + 0.75(SOLADD) + 3.45cDRYT) + 0.52(CP) _ 14.59 + 0.75cSOLADD) + 3.48cDRYT) + 0.5 l(CP) + 0.20(TOTFAT) - 26.55 + 0.72(SOLADD) + 3.8l(DRYT) + 0.47(CP) + 0.25cTOTFAT) + 0.1 S(PDEG)
a Coefficients obtained from Maximum R square procedure of SAS. b SOLADD = soluble addback; DRYT = drying temperature; CP = crude protein; TOTFAT = total fat; PDEG = pepsin degradation. ’ Mallows’ ”goodness of tit” statistic based on total squared error.
24
I.K. Yoon et al./Animal Feed Science Technology 60 (1996) 13-27
Table 5 Best tit simple and multiple regression equations to predict in situ estimates (BAGDEG) of ruminal degradation of fish meal protein using all the measured variables a Equation b
CP c
R2
Prediction equations
1
2 3
157.4 18.7 15.8
0.872 0.978 0.981
4
13.2
0.985
5
6.5
0.991
22.33 + O.B2(MEANSOL) b 41.11+ I~~!XDEGRATE)-0.76(BAGDPER) 38.32+2015(DEGRATE)-0.86(BAGDPER)+ O.OI(FICDPER) 35.29 + 2046(DEGRATE)-0.85(BAGDPER) + 0.1O(FICDPER) + 6.96(TVN) 17.83 + 1823cDEGRATE)- 0.56(BAGDPER) + 0.26@ICDPER)- 0.3l@ICDEG) + 0.80(MEANSOL)
a Coefficients obtained from Maximum R square procedure of SAS. b MEANSOL = mean of the three estimates of protein solubility (SOLADD, FICSOL, and DEGTO); DEGRATE = in situ estimate of degradation rate; BAGDPER = insoluble degradable fraction as a percentage of BAGDEG; FICDPER = insoluble degradable fraction as a percentage of FICDEG; TVN = total volatile nitrogen; FICDEG = ficin degradation. ’ Mallows’ “goodness of fit” statistic based on total squared error.
Because all estimates of protein solubility (SOLADD, FICSOL and DEGTO) were highly correlated with BAGDEG (Fig. 2) and were highly correlated with each other (Table 3), a mean of the three estimates (MEANSOL) was used when prediction equations were developed from all measured variables. Solubility again accounted for a major proportion (87%) of the variation in BAGDEG (Table 5). When all measured variables were considered, a five component equation provided the best fit (maximum coefficient of determination (I?*> and Mallows’ criteria) and accounted for 99% of the variation in BAGDEG.
Table 6 Characteristics and nutrient content of fish meal samples used for validation of prediction equations a Nutrient content
Characteristics Sample
I 2 3 4 5 6 7 8 9 10
TVN b
DRYT ’
SOLADD b
CP b
TOTFAT b
0.17 0.19 0.13 0.16 0.18 0.08 0.10 0.07 0.06 0.09
2 2 1
21.2 17.1 13.7 13.7 16.3 1.3 0.0 3.0
68.0 69.8 70.5 69.6 69.1 68.4 71.0 70.0 70.7 67.8
10.3 9.9 9.6 9.8 10.6 8.7 7.9 6.1 6.8 6.3
1 1
1 1
1 1 2
0.0 1.2
a TVN = total volatile nitrogen; DRYT = drying temperature; SOLADD = soluble addback; CP = crude protein; TOTFAT = total fat. b Percentage of dry matter. ’ 1 = drying temperature. < 60°C; 2 = drying temperature between 60 and 88°C.
I.K. Yom et al./Animal Table 7 Comparisons
of ruminal degradation
from prediction
equations
Feed Science Technology 60 (1996) 13-27
of fish meal (FM) protein estimated
25
from in situ procedure
or calculated
a,b
FM
BAGDEGe
BAGDEGpl
BAGDEGp2
BAGDEGp3
BAGDEGp4
BAGDEGp5
I 2 3 4 5 6 7 8 9 10
41.4 41.0 39.8 37.0 35.0 32.9 32.3 29.9 29.8 27.4
43.4 (2.0) 40.5 (- 0.5) 38.1 (- 1.7) 40.0 (3.0) 38.2 (3.2) 29.4(-3.5) 28.5 (- 3.8) 30.6 (0.7) 28.5 t - 1.3) 29.3 (1.9)
44.9 (3.5) 42.0 ( 1.O) 36.6 (- 3.2) 38.4 (1.4) 36.7 (1.7) 28.0 (- 4.9) 272-5.1) 29.2 (- 0.7) 27.2 (- 2.6) 3 1.O (3.6)
44.9 (3.5) 42.7 (1.7) 37.0 (- 2.8) 38.3 (1.3) 36.6 (1.6) 26.7 (- 6.2) 27.1 (-5.2) 28.8(1.1) 26.9 (- 2.9) 29.7 (2.3)
45.0 42.8 37.0 38.5 36.6 26.5 26.7 28.0 26.3 29.1
42.1 (0.7) 40.0 ( - 1.O) 34.2 (- 5.6) 35.6 (- 1.4) 33.9(1.1) 24.2 (- 8.7) 24.9 (- 7.4) 26.0 (- 3.9) 24.4 (- 5.5) 27.3 (- 0.2)
Mean
34.7
346-0.1)
34.1 ( - 0.6)
33.9 (- 0.8)
33.6(-
(3.6) (1.8) (- 2.8) (1.5) (1.6) (- 6.4) (- 5.6) ( - 1.9) (- 3.5) (1.7) 1.1)
31.3 (-3.4)
a BAGDEGe = estimation of BAGDEG by in situ procedure; BAGDEGpl = calculated BAGDEG from prediction Eq. (1); BAGDEGp2 = calculated BAGDEG from prediction Eq. (2); BAGDEGp3 = calculated BAGDEG from prediction Eq. (3); BAGDEGp4 = calculated BAGDEG from prediction Eq. (4); BAGDEGp5 = calculated BAGDEG from prediction Eq. (5). F’rediction equations are presented in Table 5. b Numbers in parenthesis represent the deviation from the estimated values.
Prediction equations developed from all measured variables (Table 5) demonstrate in situ measurements of rate of degradation and the proportion of degradable protein that is insoluble explain most of the variation in BAGDEG. Conducting the in situ measurements eliminates the need to predict BAGDEG. Thus, we did not attempt to evaluate the prediction equations listed in Table 5. Ten additional FM samples (Table 6) were used to determine if the prediction equations (Table 4) developed from routine industry measures provide reliable estimates of ruminal protein degradation. Estimates of BAGDEG were calculated from the developed equations and compared (Table 7) to BAGDEG values obtained from the in situ technique. Coefficients of determination and probabilities for comparisons of determined BAGDEG with predicted values from equations 1, 2, 3, 4 and 5 were R2 = 0.81, P = 0.0004; R* = 0.76, P = 0.001; R* = 0.79, P = 0.0006; R* = 0.80, P = 0.0005; R* = 0.79, P = 0.0006, respectively. Results demonstrate the one variable equation using SOLADD is highly correlated with BAGDEG measurements and provides a simple, rapid and inexpensive way to predict ruminal degradation of menhaden FM protein.
4. Conclusions Results confirm that FM characteristics affect the extent of degradation of FM protein in the rumen. Degradation of FM protein from different processing plants can be predicted by estimates of protein solubility. However, inclusion of estimates of degradation (e.g., degradation rate, insoluble degradable fraction of protein, etc.) will improve the ability to accurately predict total degradation. The fish meal industry can utilize
26
I.K. Yoon et al./Animal Feed Science Technology 60 (1996) 13-27
routine processing characteristics (SOLADD and DRYT) or soluble protein measurements to predict ruminal degradation of their products. These simple, rapid and inexpensive measurements can be used to obtain reliable estimates of ruminal degradation of FM protein.
Acknowledgements Published as paper no. 22,071 of the scientific journal series of the Minnesota Agricultural Experiment Station on research conducted under project nos. 16-045 and 16-048 supported by the College of Agriculture.
References Association of Official Analytical Chemists, 1984. Official methods of analysis. 14th edn., AOAC, Washington, DC. Beever, D.E., Thomson, D.J. and Cammell, S.B., 1976. The digestion of frozen and dried grass by sheep. J. Agric. Sci. (Camb.), 86: 443-452. Broderick, G.A., 1980. Estimation of protein degradation using in situ and in vitro methods. In: F. N. Owens (Editor), Protein Requirements for Cattle: Symposium. Nov. 19-21, at Oklahoma State University, Stillwater, OK, pp. 72-80. Broderick, G.A., Wallace, R.J., 0rskov, E.R. and Hansen, L., 1988. Comparison of estimates of ruminal protein degradation by in vitro and in situ methods. J. Anim. Sci., 66: 1739-1745. Calsamiglia, S., Stem, M.D. and Firkins, J.L. 1995. Effects of protein source on nitrogen metabolism in continuous culture and intestinal digestion in vitro. J. Anim. Sci. 73: 1819-1827. Chen, Cl., Sniffen, C.J. and Russell, J.B., 1987. Concentration and estimated flow of peptides from the rumen of dairy cattle: effects of protein quality, protein solubility and feeding frequency. J. Dairy Sci., 70: 983-992. Clark, J.H. and Davis, C.L., 1980. Some aspects of feeding high producing dairy cows. J. Dairy Sci., 63: 873-885. Clark, J.H., Murphy, M.R. and Crooker, B.A., 1987. Supplying the protein needs of dairy cattle from by-product feeds. J. Dairy Sci., 70: 1092-l 109. Clark, J.H., Klusmeyer, T.H. and Cameron, M.R., 1992. Microbial protein synthesis and flows of nitrogen fractions to the duodenum of dairy cows. J. Dairy Sci., 75: 2304-2323. Crooker, B.A., Sniffen, C.J., Hoover, W.H. and Johnson, L.L., 1978. Solvents for soluble nitrogen measurements in feedstuffs. J. Dairy Sci., 61: 437-447. Goldhor, S. and Regenstein, J.M., 1987. Fish meal in livestock feeds: new fmdings. hoc. Cornell Nutr. Conf., Ithaca, NY, pp. 98- 105. Han, Y. and Parsons, C.M., 1991. Protein and amino acid quality of feather meals. Poultry Sci., 70: 812-822. Hussein, H.S. and Jordan, R.M., 1991. Fish meal as a protein supplement in ruminant diets: a review. J. Anim. Sci., 69: 2147-2156. Johnston, J. and Coon, C.N., 1979. The use of varying levels of pepsin for pepsin digestion studies with animal proteins. Poultry Sci., 58: 1271- 1273. Kaufmann, W. and Lupping, W., 1982. Protected proteins and protected amino acids for ruminants, In: E. L. Miller, 1. H. Pike and A. J. H. Van Es (Editors), Protein Contribution of Feedstuffs for Ruminants. Butterworths, London, pp. 36-75. Laycock, K.A. and Miller, E.L., 1981. Nitrogen solubility and protein degradability of commercially and laboratory prepared rapeseed and soya-bean meals. Proc. Nutr. Sot., 40: 103A (Abstr.). Lindquist, K.J., Crooker, B.A., Illg, DJ. and Stem, M.D., 1989. Evaluation of ticin assay for estimating ruminal degradation of dietary protein. J. Anim. Sci. 67(Suppl. 1): 496.
I.K. Yom et al./Animal Mahadevan,
Feed Science Technology 60 (1996) 13-27
S., Erfle, J.D. and Sauer, F.D., 1980. Degradation
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of soluble and insoluble protein by Bactrroides
umylophdus protease and by rumen microorganisms. J. Anim. Sci., 50: 723-728. Mallows. CL., 1973. Some comments on Cp. Technometrics., 15: 661-676. Mathers, J.C. and Miller, E.L., 1981. Quantitative studies of food protein degradation and the energetic efficiency of microbial protein synthesis in the rumen of sheep given chopped luceme and rolled barley. Br. J. Nun., 45: 587-604. Mehrez, A.Z., Brskov, E.R. and Opstvedt, J., 1980. Processing factors affecting degradability of fish meal in the tumen. J. Anim. Sci., 50: 737-744. Miller, E.L., 1973. Evaluation of foods as sources of nitrogen and ammo acids. Proc. Nutr. Sot., 32: 79-84. Opstvedt, J., Miller, R., Hardy, R.W. and Spinelli, J., 1984. Heat-induced changes in sulthydryl groups and disultide bonds in fish protein and their effect on protein and amino acid digestibility in rainbow trout. J. Agric. Food Chem., 32: 929-935. 0rskov, E.R.. Fraser, C. and McDonald, I., 1971. Digestion of concentrates in sheep. 2. The effect of urea or fish-meal supplementation of barley diets on the apparent digestion of protein, fat, starch and ash in the mmen, the small intestine and the large intestine, and calculation of volatile fatty acid production. Brit. J. Nutr., 25: 243-252. Owens, F.N. and Bergen, W.G., 1983. Nitrogen metabolism of ruminant animals: historical perspective current understanding and future implications. J. Anim. Sci., 57(Suppl. 2): 4988518. Poos-Floyd, M., Klopfenstein, T. and B&ton, R.A., 1985. Evaluation of laboratory techniques for predicting mminal protein degradation. J. Dairy Sci., 68: 829-839. Roe, M.B., Chase, L.E. and Sniffen, C.J., 1991. Comparison of in vitro techniques to the in situ technique for estimation of ruminal degradation of protein. J. Dairy Sci., 74: 1632-1640. Statistical Analysis Systems Limited Inc., 1985. SAS User’s Guide: Statistics, Version 5 edn., SAS Institute, Inc., Gary, NC, USA. Stem, M.D. and Satter, L.D., 1984. Evaluation of nitrogen solubility and the Dacron bag technique as methods for estimating protein degradation in the rumen. J. Anim. Sci., 58: 714-724. Stem, M.D., Rode, L.M., Prange, R.W., Stauffacher, R.H. and Satter, L.D., 1983. Ruminal protein degradation of corn gluten meal in lactating dairy cattle fitted with duodenal t-type cannulae. J. Anim. Sci., 56: 194-205. Stokes, S.R., Hoover, W.H., Miller, T.K. and Blauweikel, R., 1991. Ruminal digestion and microbial utilization of diets varying in type of carbohydrate and protein. J. Dairy Sci., 74: 871-88 I. Tamminga, S., 1982. Energy-protein relationships in ruminant feeding: similarities and differences between rumen fermentation and postruminal utilization. In: E. L. Miller, I. H. Pike and A. J. H. Van Es (Editors), Protein Contribution of Feedstuffs for Ruminants. Butterworths, London, pp. 4- 17. Van Vuuren, A.M., Krol-Kramer, F., Van Der Lee, R.A. and Corbijn, H., 1992. Protein digestion and intestinal amino acids in dairy cows fed fresh Lolium perenne with different nitrogen contents. J. Dairy Sci., 75: 2215-2225.