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Effect of borage meal on nutrient digestibility and performance of ruminants and pigs
ANIMAL FEED SCIENCE AND TECHNOLOGY
ELSEVIER
Animal Feed Science Technology
64 (1997) 273-285
Effect of borage meal on nutrient digestibility and performance of ruminants and pigs A.F. Mustafa, J.J. McKinnon Department
ofAnimaland
Poultry
*,
P.A. Thacker, D.A. Christensen
Science, 72 Campus Drice,
CJniversi@ of Saskatchewan,
Saskatoon.
Sask..
CanadaS7N5B5
Accepted 22 March 1996
Abstract Borage meal (BM) is derived from the processing of borage (Borage oficinalis) seeds. A series of experiments was conducted to determine the nutritive value of BM as a protein supplement for ruminants and pigs. In situ ruminal effective crude protein degradability (ECPD) was determined for BM relative to four other protein supplements using two ruminally fistulated cows in a randomized complete block design. The protein supplements used for comparsion purposes included two that are high in rumen degradable protein (soybean (SBM) and canola (CM) meals) and two high in rumen undegradable (corn gluten (CGM) and heated canola (HCM) meals) protein. ECPD of borage meal was intermediate to that of the other four protein supplements studied with the following order observed: SBM > CM > BM > HCM > CGM. Voluntary intake (VI) and apparent nutrient digestibility coefficients and digestible energy (DE) content of barley grain and dehydrated alfalfa based diets containing graded levels of BM (0, 6, 12 and 18%) were determined in a completely randomized design using 16 growing lambs. No effect (P > 0.05) of BM inclusion rate was observed on VI, nutrient digestibility coefficients and DE values. In two experiments with swine, BM was included at 0, 10, 20, 30, and 40% in grower diets and 0, 6.75, 13.5, 20.25 and 27% in finisher diets. Both rate and efficiency of gain were depressed in a linear fashion (P < 0.05) as the level of BM in the diet increased. Digestibility coefficients for dry matter, crude protein and gross energy also declined linearly (P < 0.05) as dietary BM increased. It was concluded that BM has potential as a protein supplement for ruminants. However, results of the pig experiments showed poor performance when BM was included in grower and finisher diets. Keyvordsr
Borage meal; Ruminants;
* Corresponding
PII
author.
Copyright SO377-8401(96)01040-1
0377-8401/97/$17.00
Swine; Nutrient utilization
0 1997 Elsevier Science B.V. All rights reserved
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A.F. Mustafa et al. /Animal Feed Science Technology 64 (1997) 273-285
1. Introduction Borage (Borage o&inalis) is an annual herb, native to the Mediterranean area, but cultivated throughout the world. The plant is used for medicinal purposes as well as for preparing salads and beverages (Larson et al., 1984). The economic importance of borage seed has increased in the last few years because of its high content of gamma linolenic acid (GLA) which is used by the body as a precursor for prostaglandin synthesis (Chapkin and Carmichael, 1990). Borage has an advantage over other sources of GLA, since it is an annual plant with large seeds. These characteristics facilitate harvest and oil extraction. Borage seed has been reported to contain about 32% oil, 24% GLA and 3% erucic acid (Galwey and Shirlin, 1990). Borage meal is produced as a by-product when borage seeds are crushed to obtain their oil. Currently, there is a limited supply of borage meal as there are no commercial crushing plants. However, if the demand for borage oil increases, a concurrent increase in the supply of borage meal will result. Proper utilization of the meal as an animal feed will eventually increase the economic value of the plant as a cash crop. At present, there is very little information on the feeding value of this byproduct for livestock. As such, it is important to examine the nutritive value of borage meal and to report the findings to the livestock industry. The objectives of this study were to determine the chemical composition and rumen degradability characteristics of borage meal and to compare these characteristics to other common protein supplements for ruminants and to determine the voluntary intake (VI) and nutrient digestibility coeficients of borage meal supplemented diets when fed to growing lambs and pigs.
2. Materials and methods 2.1. Rumen in situ incubations 2. I. 1. Chemical composition Borage meal was obtained from PGE, Canada, Ltd., (Saskatoon, Saskatchewan). For comparsion purposes, four additional protein supplements were studied (Table 1). Canola, soybean and corn gluten meals were obtained from a commercial feed mill (Federated Cooperatives Ltd., Saskatoon, Sk., Canada). Heated canola meal was prepared by heating commercially available canola meal to 125°C for 20 min in a vaccum tumble dryer according to the procedure described by McKinnon et al. (1991). The four protein sources used for comparsion purposes were choosen on the basis of their rumen degradability characteristics. Canola and soybean meals are considered good sources of rumen degradable protein (Kirkpatrick and Kennelly, 1987) while heated canola and corn gluten meals are considered good sources of rumen undegradable protein (McKinnon et al., 1995; Murphy and Kennelly, 1987). Samples of the five protein sources were analyzed for dry matter (DM), ash, ether extract (EE), crude protein (CP) and acid detergent lignin according to the methods of the Association of Official Analytical Chemists (AOAC, 1990). Neutral (NDF) and acid (ADF) detergent fibre were analyzed using the method of Van Soest et al. (1991).
A.F. Mustafa et al/Animal Table 1 Chemical
composition
Feed Science Technology 64 (1997) 273-285
21s
of five protein sources used in the rumen in situ trial
Chemical fraction (g kg-’ DM basis)
Ash Ether extract Crude protein (CP) Fiber fractions Neutral detergent fibre Acid detergent fibre Acid detergent lignin Protein fractions (g kg -’ of CP) Soluble CP Non-protein nitrogen Neutral detergent insoluble CP Acid detergent insoluble CP Degradable CP
Protein source Borage meal
Soybean meal
canola meal
Heated canola meal
Corn gluten meal
137 71 334
66 16 494
74 58 406
76 57 381
23 10 627
350 227 65
125 44 5
327 198 76
507 223 137
138 107 10
232 215 189 102 654
112 52 24 17 716
324 264 159 55 639
88 89 557 110 327
6 6 47 44 69
Neutral and acid detergent insoluble nitrogen were determined on NDF and ADF residues, respectively, using the Kjeldahl method (AOAC, 1990). The mineral composition of borage meal was determined following digestion with a perchloric-nitric acid mixture (AOAC, 1990) using a Pet-kin-Elmer Mode1 5000 atomic absorption spectrophotometer (Technicon GTPC autoanalyzer II>. Phosphorus content was determined colorimetericaly (Pharmacia LKB utraspec III). For the five protein sources, in vitro protein solubility and degradability were determined following the procedures of Roe et al., 1990. For protein solubility, duplicate samples (0.5 g) were weighed into 125 ml Erlenmeyer flasks. Samples were incubated in 50 ml of borate-phosphate buffer (pH 6.7) for 1 h at 39°C. Protein degradability was estimated by weighing duplicate samples (0.2 g air dry protein) into Erlenmeyer flasks. The samples were soaked in 40 ml of borate-phosphate buffer and incubated for 1 h at 39°C. Following incubation, 10 ml of fresh protease solution (protease type XIV from Streptom.yces griseus, Sigma Chemical Co., St. Louis, MO) was added to each flask and the solution incubated at 39°C for 18 h. The insoluble residues were filtered through Whatman # 54 filter paper and residual nitrogen determined using the Kjeldahl method (AOAC, 1990). Protein solubility and degradability were expressed as percent of total protein (N X 6.25). Non-protein nitrogen was determined by precipitating true protein using sodium tungstate as a precipitating agent (Greenberg and Shipe, 1979).
2.1.2. Rumen incubations Rumen CP kinetic parameters and effective degradabilities of the five protein supplements were determined using two non-lactating Holstein cows fitted with flexible rumen fistulae. The cows were fed a 50:50 barley si1age:barley concentrate diet (DM basis), twice daily (08.00 and 16.00 h) at 1.5% of body weight (DM basis). The
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A.F. Mustafa et al. /Animal
Feed Science Technology 64 (1997) 273-285
Table 2 In situ rumen crude protein (CP) kinetic parameters
and effective degradability
of five protein sources
Protein source
S.E.M. 4
Borage meal
Soybean meal
Canola
Heated
meal
canola meal
Corn gluten meal
31.9 x 45.4 w 9.8 ’ 61.7 ’
11.7 88.3 10.3 71.2
29.8 y 70.2 ’ 6.0 y 68.0 y
12.5 ’ 86.6 y 1.4 L 34.3 w
2.3 NJ’ 97.7 x 0.5 L 11.2 ”
Protein kinetic parameters ’ Soluble fraction (%) Potentially degradable fraction (%) Degradation rate (% h-‘) Effective degradability (%) *
z y x ’
0.44 1.44 0.37 0.85
’ Derived from the equation of Brskov and McDonald (1979): a + b * (I-Ed”), where a is soluble fraction, is degradable fraction and c is rate of degradation of b fraction. * Calculated assuming rumen flow rate of 5% h-’ ’ x, y, z, w, v Means in the same row with different superscripts differ (P < 0.05). 4 S.E.M = Standard error of the mean.
b
concentrate consisted of 74.5% barley, 17% canola meal, 2% corn gluten meal, 2% molasses, 0.5% canola oil, 0.6% dicalcium phosphate, 0.3% cobalt-iodized salt, 0.1% ground limestone and 3% mineral-vitamin mix. Analysis of the diet indicated the following nutrient profile: 17.7% CP; 41.2% NDF; 21.0% ADF; 0.8% calcium (Ca); and 0.7% phosphorus (P>. The in situ rumen incubation consisted of six time periods. These included 2, 4, 6, 8, 12 and 24 h following the morning feeding. Duplicate samples (7 g> of each meal were placed in nylon bags (9 X 21 cm; 41 pm porosity) and incubated in the rumen of each cow at the specified time period. The bags were inserted for the specified times and removed together from the rumen at the completion of the incubation. Following removal from the rumen, the bags were washed and handled as described by McKinnon et al. (1991). Ruminal CP disappearance at each incubation time was calculated from the CP content of the original samples and the residues following rumen incubation. Ruminal CP disappearance data was utilized to estimate ruminal CP kinetic parameters (Table 2) using the equation of 0rskov and McDonald (1979): P=a+b*(l
-epC’)
where P is CP disappearance at time t, a is the rapidly soluble CP fraction (%), b is the insoluble but degradable CP fraction (%) and c is the rate constant at which b is degraded (% h- ’>. The constants a, b and c were estimated by an iterative least-square method using the nonlinear regression procedure of the Statistical Analysis Systems Institute (1989) with the constraint that a + b I 100. Effective ruminal CP degradability (ECPD) of each protein supplement at a 5% rumen flow rate (k) was estimated using the equation of 0rskov and McDonald (1979): ECPD=a+b*c/(c+k) where a,
b
and c are defined as above.
A.F.
Table 3 Ingredients
Mustafa et al. /Animal
and chemical
composition
Feed Science Technology 64 (1997) 273-285
of borage supplemented
211
diets used in the sheep trial
Borage meal inclusion rate (“/c of diet) 0 Ingredient (% DM basis) Barley 54.0 Dehydrated alfalfa meal 41.0 Borage meal 0.0 Molssas 2.0 Salt 2.0 Mineral supplement a 1.0 Chemical composition (g kg-’ DM basis) Ash 78 Crude protein 151 Acid detergtent tibre 147 Calcium IO Phosphorous 3 Gross energy (MJ kg-’ )
18.0
6
12
18
54.0 35.0 6.0 2.0 2.0 1.0
54.0 29.0 12.0 2.0 2.0 1.0
54.0 23.0
79 170 157 3
80 178 158 10 4
81 186 160 10 4
18.0
18.0
18.4
I
18.0 2.0 2.0 1.0
AContained 16% Ca, 16% P, 1500 mg kg-’ Zn, 25 mg kg-’ I, 100 mg kg-’ Fe, 640 mg kg-’ Mn. 14 mg kg~’ Co. 3000 mg kg-’ F, 151,800 IU kg-’ vitamin A, 15,181 IU kg-’ vitamin D, 500 IU kg-’ vitamin E.
2.2. Voluntary intake (VI) and total tract digestibility
studies
2.2.1. Sheep trial Voluntary intake and nutrient digestibility of diets formulated with graded levels of borage meal were determined using 16 growing ram lambs (39.8 + 3.0 kg). The animals were housed in individual metabolism crates and were fed one of four experimental diets. The control diet contained dehydrated alfalfa meal as a supplemental protein source. In Diets 2, 3 and 4, borage meal replaced dehydrated alfalfa meal at 6, 12 and 18% substitution levels (Table 3). The chemical composition and gross energy (GE) content of the experimental diets are shown in Table 3. Crude protein and ADF levels increased with borage meal inclusion rate. However, all diets met CP requirements for growing and finishing lambs (National Research Council, 1985). All diets were pelleted (4.8 mm diameter) and offered twice daily in equal portions at 08.00 and 15.00 h. The protocol of the digestibility trial consisted of a 7 day adaptation period, seven days to determine voluntary intake (VI), three days of restricted intake (85% of VI) and a 5 day total faecal collection period. Faeces were collected once daily, subsampled (10% of total faecal output) and dried in a forced air oven at 65°C for 72 h. Faecal samples were cornposited by animal over the 5 day collection period. Feed samples were collected simultaneously and dried in a similar manner to faecal samples. Feed and faecal samples were ground in a Christi-Norris mill (1.0 mm screen) and stored for chemical analyses. Feed and faecal samples were analyzed for DM, ash, CP and ADF as described above. Gross energy (GE) content was determined on dried feed and faecal samples using an adiabatic oxygen bomb calorimeter. Apparent nutrient digestion coefficients (Table 4) were calculated as the difference between nutrient intake and excretion in fecal material and expressed as a percentage of intake.
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A.F. Mustafa et al. /Animal
Table 4 Effect of borage meal inclusion
Feed Science Technology 64 (1997) 273-285
rate on voluntary
Parameter
intake and nutrient digestibility
Borage meal inclusion rate (% of diet)
Intake Dry matter (% BW ‘1 Dry matter intake (g kg BW-“-75) Digestibility coeffwients (o/o) Dry matter Organic matter Crude protein Acid detergent libre Gross energy Digestible energy (h4J kg”)
0
6
12
18
4.5 114.2
4.2 105.9
4.6 118.0
4.6 116.5
0.20 5.39
71.2 72.4 70.8 31.3 68.2 12.6
69.5 70.8 70.3 28.5 67.4 11.6
70.4 71.9 71.9 28.2 68.5 12.7
70.1 71.9 70.3 27.4 68.3 12.7
1.35 1.28 1.52 2.75 1.63 0.29
a Polynomial contrast indicated linear CL), quadratic b S.E.M. = Pooled standard error of the mean. ’ BW = body weight.
of diets fed to sheep
S.E.M. b
Contrast a
L
Q
C
NS NS NS NS NS NS NS NS NS
NS NS NS NS NS NS NS NS NS
NS NS NS NS NS NS NS NS NS
(Q), or cubic (C) effect (NS = not significant
at P = 0.05).
2.2.2. Pig trials 2.2.2.1. Experiment 1. Sixty female crossbred pigs (Yorkshire X Landrace) weighing an average of 22.2 & 0.4 kg were assigned on the basis of weight and litter to one of five barley-soybean meal based diets. During the growing period (22 to 65 kg), the diets contained 0, 10, 20, 30 or 40% borage meal while during the finishing period (65 to 83 kg) the diets contained 0, 6.8, 13.5, 20.3 or 27.0% borage meal (Table 5). The diets contained 176 g kg-’ CP and 8.5 g kg- ’ lysine in the growing period (22 to 65 kg) and
Table 5 Formulation
of diets to determine
the effects of graded levels of borage meal on pig performance Finishing period
Growing period Level of borage meal (W) 0 Form&ion of diets (% as fed) Barley 78.40 Soybean meal 17.15 Borage meal Tallow 0.80 Dicalcium phosphate 1.75 Limestone 1.15 Salt (iodized) 0.50 Vitamin-mineral premix a 0.25 Synthetic lysine
Level of borage meal (%)
10
20
30
40
0
6.75
13.50
20.25
27.00
70.92 12.80 10.00 3.10 1.60 0.80 0.50 0.25 0.03
63.45 8.40 20.00 5.45 1.45 0.42 0.50 0.25 0.08
55.99 4.00 30.00 7.80 1.30 0.03 0.50 0.25 0.13
48.10
83.15 11.70 1.30 1.82 1.15 0.50 0.25 0.12
77.75 8.80 6.75 2.90 1.70 1.20 0.50 0.25 0.15
72.30 5.95 13.50 4.42 1.65 1.25 0.50 0.25 0.18
66.84 3.10 20.25 6.00 1.55 1.30 0.50 0.25 0.21
61.55
40.00 9.80 1.17 0.50 0.25 0.18
27.00 7.60 1.45 1.40 0.50 0.25 0.25
a Supplied per kg of diet: 4125 I.U. vitamin A; 275 I.U. vitamin D3; 13.5 I.U. vitamin E; 2 mg vitamin K, 1 mg thiamin; 4 mg riboflavin; 22 mg niacin; 16.5 mg pantothenic acid; 14 ug vitamin B-12; 250 mg choline chloride; 0.12 mg biotin; 3 mg copper; 40 mg iron; 21.3 mg manganese; 76.5 mg zinc; 0.05 mg selenium.
A.F. Mustafa et al. /Animal Feed Science Technology 64 (19971273-285 Table 6 Chemical composition
(g kg-’ % as fed) of diets fed to growing/finishing
219
pigs to determine the nutritive value
of graded levels of borage meal Growing period
Finishing period
Level of borage meal (%) ’
Level of borage meal (%) a
0
10
20
30
JO
0
6.15
13.50
20.25
27
115.6 175.1 54.3 22.0 65.4
110.7 172.9 58.0 48.7 90.6
111.9 180.1 64.0 73.4 107.1
110.7 175.4 69.6 98.1 132.2
112.6 178.3 74.4 117.1 151.5
81.1 168.7 53.1 41.0 63.0
7.93 169.0 53.6 50.8 79.9
87.6 167.8 59.4 61.8 94.1
85.5 168.5 64. I 78.8 103.0
81.2 167.5 68.3 96.6 128.9
129.4 179.4 54.4 29.7 54.6
124.1 176.7 56.5 54.9 75.2
123.8 176.9 61.6 76.3 105.5
121.7 176.5 65.8 95.6 130.8
121.3 180.8 71.3 119.1 148.5
117.5 163.3 54.4 31.9 59.2
122.6 160.8 59.1 47.5 85.0
115.3 160.8 66.0 62.0 101.3
113.7 163.9 73.9 82.1 126.3
110.5 160.0 78.4 96.1 135.9
Experiment I Moisture Crude Protein Ash Ether extract Acid detergent fibre Experiment 2 Moisture Crude Protein Ash Ether extract Acid detergent fibre a % as fed.
167 g kg-' CP in the finishing phase (65 to 83 kg) (Table 6). Tallow was added to keep the diets isocaloric while additional lysine was added to compensate for the low lysine level of borage meal relative to soybean meal (Table 7). All other essential amino acids, vitamins and minerals were present in sufficient amounts to meet or exceed the requirements recommended by the National Research Council (1988). The diets were pelleted (low pressure steam) with the temperature in the conditioning chamber maintained below 60°C.
Table 7 Essential amino acid composition
(g kg-’ as fed) of diets fed to growing/finishing
pigs in experiment
SBM ’
0
10
20
30
40
0
6.75
13.50
20.25
27.00
Arginine Histidine Isoleucine Leucine Lysine
23.9 7.7 10.3 16.9 11.0
30.7 11.1 18.0 32.7 28.3
11.3 4.4 6.3 12.3 8.7
12.0 4.3 6.1 11.5 8.6
12.8 4.4 6.2 11.5 8.7
13.4 4.0 6.0 10.5 8.4
13.7 4.1 6.0 10.3 8.4
10.3 4.0 5.8 11.4 8.6
10.4 3.9 5.6 11.0 8.6
10.6 3.8 5.4 10.3 8.2
10.9 3.8 5.4 10.0 8.4
3.1 5.2 9.6 7.9
Methionine Phenylalanine Threonine Valine
1.6 10.7 9.1
6.2 21.7 17.0 18.6
2.1 8.2 6.2 7.6
2.8 7.7 6.0 7.4
2.3 7.7 6.1 7.5
2.0 6.8 5.7 7.0
2.0 6.8 5.7 7.0
2.2 7.7 5.8 7.3
2.0 7.4 5.7 7.1
2.6 7.1 5.4 6.9
2.0 6.8 5.4 6.7
2.6 6.5 5.1 6.4
a % as fed. h soybean meal
11.2
Growing period
Finishing period
Level of borage meal (%I a
Level of borage meal (%c) ’
1
Borage meal
11.2
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A.F. Mustafa et al. /Animal Feed Science Technology 64 (1997) 273-285
The pigs were housed four to a pen in concrete pens measuring 2.7 X 3.6 m. The pens were equipped with four self feeders. The pigs were allowed individual access to their specific self-feeder for 30 min, twice daily. The pigs were weighed at weekly intervals. Feed consumption was determined on an individual basis at the time of weighing. The trial was run for 84 days and concluded when the pigs reached an average weight of 83.2 f 1.1 kg. One pig experienced a gastric ulcer while on the test and was removed from the experiment. Digestibility coefficients for DM, CP and GE were determined using 20 pigs from the growth trial, starting at an average weight of 37.9 f 1.1 kg. The pigs were housed under identical conditions and fed the same diets as those used during the growing stage, modified only by the addition of 0.5% chromic oxide as a digestibility indicator. The chromic oxide containing diets were fed for 10 days, with an eight day adaptation period followed by two days of faecal collection. Faeces were collected twice daily, immediately following feeding, by driving the pigs to a clean room where freshly voided feces were obtained. Faecal samples were then frozen. Prior to analysis, the frozen faeces were placed in a forced-air oven and dried for 48 h at 66°C and then ground (1 mm screen). Samples of feed and faeces were analyzed for DM, CP, ash, EE and ADF according to the methods of the AOAC (1990). Gross energy was determined with an adiabatic oxygen bomb calorimeter. Amino acid analysis of the borage and soybean meals and the grower diets were carried out using a Perkin-Elmer Series 4 Liquid Chromatograph following hydrolysis for 22 h with 6 N HCl. Chromic oxide was determined by the method of Fenton and Fenton (1979). 2.2.2.2. Experiment 2. Twenty barrows and 40 gilts (Yorkshire X Landrace) obtained from the same source as those in the previous trial, weighing an average of 28.0 f 0.5 kg were assigned on the basis of sex, weight and litter to one of the same dietary treatments used in the first swine trial. The diets averaged 178 and 162 g kg-’ CP during the growing (27.5 to 53.5 kg) and finishing (53.5 to 84.6 kg) periods, respectively (Table 6). All esential vitamins and minerals were present in sufficient amounts to meet or exceed requirements as recommended by the National Research Council (1988). Pigs were housed and fed in a similar manner to that described for Experiment 1. All diets were pelleted as described for Experiment 1. The trial was run for 70 days and terminated when the pigs reached an average weight of 87.0 k 1.2 kg. One pig died during the experiment from a twisted gut. 2.2.3. Statistical analysis Statistical analysis was carried out using the General Linear Model procedure of Statistical Analysis Systems Institute (1989). Data from the rumen in situ trial was analyzed as a randomized complete block design with the two cows serving as blocks. Where appropriate, means were separated using the Student-Neuman-Keuls procedure (Steel and Torrie, 1980). Data from the sheep trial were analyzed as a completely randomized design (four treatments and four replicates). The data in Experiment 1 of the pig trial was analyzed as a one way analysis of variance while Experiment 2 was analyzed as a 2 X 5 factorial with sex, treatment and their interaction being accounted
A.F. Mustafa et al./Animal
Feed Science Technology 64 ClYY7l273-285
781
for in the model. Polynomial contrasts (linear, quadratic and cubic) were used to test the effect of borage meal inclusion rate on feed intake and nutrient digestibilities in the sheep and pig trials (Steel and Torrie, 1980).
3. Results and discussion
3.1. In situ incubations 3. I. I. Chemical composition The borage meal and the four other protein sources were sampled from a single batch of each meal. It is thus not possible to analyze the chemical composition data statistically. However, to the author’s knowledge, little information exists in the literature for borage meal. Therefore, it is of interest to compare its chemical composition to that of the other protein sources used in the study. Borage meal had the following mineral profile: 18.1, 9.8, 6.3, 1.3, and 17.4 (g kg-‘) calcium, phosphorus, magnesium, sodium and potassium, respectively. Trace mineral levels were 23.3, 73.5, 269.4 and 159.1 mg kg-‘, respectively, for copper, zinc, iron and manganese. Total ash content averaged 137 g kg-’ for borage meal. This value was 85.1, 107.8 and 495.7% higher than those for canola, soybean and corn gluten meals, respectively (Table 1). The ether extract content (g kg-’ ) of borage meal (71) was comparable with that of canola meal (58) but higher than that of soybean (16) and corn gluten meal (10) (Table 1). Comparsion of the neutral (NDF) and acid (ADF) detergent fibre levels of borage meal relative to the other four protein sources indicated that this protein source had a lower NDF content than heated canola meal, comparable with canola meal and higher than soybean and corn gluten meals. ADF levels were highest for borage meal, intermediate for canola and heated canola meals and lowest for soybean and corn gluten meals. The CP content of borage meal (334 g kg-‘) was 33.1, 17.7, 12.3 and 46.7% lower than soybean meal, canola meal, heated canola meal and corn gluten meal, respectively (Table 1). Acid and neutral detergent insoluble protein levels followed a similar pattern to NDF and ADF levels (Table 1). 3.1.2. In situ incubation Fitting the CP disappearance data to the Orskov and McDonald (1979) equation indicated that borage meal had the highest (P < 0.05) soluble (a value) and the lowest (P < 0.05) potentially degradable CP (b value) fraction (Table 2). Rapidly soluble CP fraction followed the order (P < 0.05): borage meal > canola meal > soybean meal = heated canola meal > corn gluten meal (Table 2). The results of the in situ trial agree well with the chemical characterization of the CP content of the five meals which indicated that borage and canola meals had the highest soluble protein content followed by soybean meal, heated canola meal and corn gluten meal (Table 1). The relative soluble CP levels of canola and soybean meals found in this study agree with those of Zinn (1993) and Kirkpatrick and Kennelly (1987). Potentially degradable CP fraction followed the order (P < 0.05): corn gluten meal > heated canola meal = soybean meal > canola meal > borage meal, respectively while the rate (c value) of CP degradation
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A.F. Mustafa et al./Aninml Feed Science Technology 64 (1997) 273-285
was highest (P < 0.05) for borage and soybean meals, followed by canola meal, and was lowest (P < 0.05) for heated canola and corn gluten meals (Table 2). The relatively low potentially degradable CP fraction of borage meal can be attributed to its high soluble CP and acid detergent insoluble protein contents (Table 1). Effective CP degradability of borage meal was lower (P < 0.05) than soybean and canola meals and higher (P < 0.05) than that of heated canola and corn gluten meals. Effective CP degradability was higher (P < 0.05) in soybean meal than canola meal and was higher (P < 0.05) in heated canola meal than corn gluten meal. Again the results of the in situ incubation are in good agreement with the chemical data. Results of the in vitro protease technique indicated that the degradable CP content was highest for soybean meal, followed by borage and canola meals and finally by the two rumen escape protein sources (Table 1). The results of the in situ study are also in good agreement with those of other researchers (Deacon et al., 1988 and Kirkpatrick and Kennelly, 1987) who have shown that soybean and canola meals are highly degraded in the rumen and thus poor sources of rumen undegradable protein. On the other hand, heated canola and corn gluten meals have been shown to be good sources of rumen undegradable protein (Murphy and Kennelly, 1987; McKinnon et al., 1995). Since the ECPD of borage meal was only 9.3% lower than canola meal and 79.9% higher than that of heated canola meal, one would classify borage meal as a relatively highly degradable protein source for ruminants. 3.2. Voluntary intake and total tract digestibility
studies
3.2.1. Sheep trial Incorporation of borage meal up to 18% of the diet had no effect on voluntary DM matter intake expressed as a percentage of body weight, which averaged 4.5 f 0.19% (range 4.2-4.60/ o) across treatments (Table 4). Similarly, no differences in intake were found when expressed on a metabolic body weight basis (Table 4). Nutrient digestibility coefficients for DM, OM, CP, and ADF were not influenced by borage inclusion level (Table 4). Consequently, DE values (MJ kg-’ DM) were similar across the four experimental diets (Table 4). These results indicate that inclusion of borage meal up to 18% of a barley grain and dehydrated alfalfa meal based diet had no effect on DM intake or apparent nutrient digestibility by growing lambs. 3.2.2. Pig trial In the first pig experiment, average daily gain was depressed in a linear (P < 0.05) manner as the inclusion level of borage meal in the diet increased (Table 8). The depression in growth appeared to result from depressed feed intake, particularly at the higher levels of borage meal inclusion. Feed efficiency was not significantly different between treatments but tended to be poorer as the level of borage meal in the diet increased, although the diet with the highest level was used fairly efficiently during the finishing period (Table 8). This is likely a reflection of the increased ability of pigs to degrade fibre as they mature (Bell and Keith, 1991). Digestibility coefficients for DM, CP and GE all declined in a linear fashion (P < 0.05) as the level of borage meal in the diet increased.
A.F. Mustafa et al./Animal
Feed Science Technology 64 (1997) 273-285
Table 8 Effect of graded levels of borage meal on pig performance
(Experiment
Level of borage meal (%) Grower period Finisher period
0.00 0.00
10.00 6.15
Growing Period (22-6.5 kg) Daily gain (kg) 0.12 0.73 Daily feed (kg) 1.74 1.86 Feed efficiency 2.41 2.52 Finishing Period (65-83 kg) Daily gain (kg) 0.90 0.89 Daily feed (kg) 2.62 2.70 Feed efficiency 2.91 3.03 Entire Experiment (22-83 kg) Daily gain (kg) 0.77 0.77 Daily feed (kg) 1.96 2.07 Feed efficiency 2.55 2.67 Digestibility % Dry matter 72.5 67.5 Crude protein 76.3 68.2 Gross energy 72.2 68.2
Q
C
0.03 0.07 0.06
0.007 0.052 NS
NS NS NS
NS NS NS
0.85 2.43 2.87
0.04 0.10 0.12
NS 0.019 NS
NS NS NS
NS NS NS
2.71
0.69 1.82 2.63
0.03 0.07 0.05
0.003 0.027 NS
NS NS NS
NS NS NS
60.0 64.3 64.5
61.9 62.4 66.9
1.87 1.58 1.69
0.0002 0.0001 0.018
NS 0.0052 NS
NS NS NS
30.00 20.25
40.00 27.00
0.69 1.73 2.52
0.65 1.65 2.56
0.64 1.62 2.57
0.84 2.47 3.07
0.75 2.32 3.12
0.72 1.91 2.65
0.67
64.0 65.4 66.5
1.82
Level of borage meal (%) 10.00 6.75
20.00 13.50
Growing Period (28-54 kg) Daily gain (kg) 0.82 0.79 0.77 Daily feed (kg) 1.76 1.77 1.79 Feed efficiency 2.12 2.24 2.32 Finishing Period (54-87 kg) Daily gain (kg) 0.94 0.98 0.96 Daily feed (kg) 2.73 2.84 2.79 Feed efficiency 2.92 2.92 2.92 Entire Experiment (28-87 kg) Daily gain (kg) 0.88 0.88 0.87 Daily feed (kg) 2.24 2.30 2.29 Feed efficiency 2.55 2.61 2.65
Contrast a L
20.00 13.50
(Q) or cubic
Table 9 Effect of graded levels of borage meal on pig performance
0.00 0.00
1)
S.E.M. b
’ Polynomial contrast indicated linear (L), quadratic P = 0.05). b S.E.M. = Pooled standard error of the mean,
Grower period Finisher period
283
(C) effects
(Experiment
S.E.M. s Contrast
(NS = not significant
2)
’
Barrows 2 Gilts
S.E.M. ’
L
Q
0.02 0.06 0.04
0.0001 0.039 0.0001
NS NS 0.77 NS NS 1.74 NS NS 2.30
0.76 1.73 2.27
0.87 2.60 3.00
0.04 0.09 0.07
NS NS NS
NS NS 1.03 a NS NS 3.00 a NS NS 2.92
0.89 b 0.03 2.62 b 0.06 2.97 0.05
0.77 2.12 2.75
0.03 0.07 0.05
0.005 NS 0.016
NS NS 0.89 a NS NS 2.37 a NS NS 2.64
0.82 b 0.02 2.18 b 0.05 2.66 0.03
30.00 20.25
40.00 27.00
0.75 1.72 2.31
0.67 1.64 2.44
0.93 2.78 3.01 0.84 2.25 2.69
at
C
0.02 0.04 0.03
’Polynomial contrast indicated linear CL), quadratic (Q) or cubic (C) effects (NS = not significant P = 0.05). ’ a, b Means in the row within sex with different superscripts are different (P < 0.05). ’ S.E.M. = Pooled standard error of the mean.
at
284
A. F. Mustafa et al. /Animal Feed Science Technology 64 (1997) 273-285
In the second experiment, rate and efficiency of gain of the pigs were also depressed in a linear fashion (P < 0.05) as the level of borage meal in the diet increased (Table 9). However, in this experiment, feed intake was only significantly affected during the growing period (28-54 kg) and only at the highest level of inclusion (40%). As expected, barrows gained faster (P < 0.05) and consumed more (P < 0.05) feed than gilts over the entire experiment. In formulating the diets for the pig experiment, an attempt was made to compensate for the known anti-nutritional shortcomings of borage meal. Since the proximate analysis (Table 1) revealed a considerably higher fibre and ash concentration in borage meal compared with soybean meal, tallow was added to the borage meal containing diets as a mean of increasing their energy content. Similarly, synthetic lysine was added to the borage meal containing diets to bring their lysine concentration up to that of the soybean meal control diet (Table 7). Despite this effort, borage meal containing diets failed to support a level of performance similar to that of pigs fed soybean meal, indicating impaired utilization of nutrients. Bell and Keith (1983) reported reductions in the digestibility of dry matter, crude protein and energy as they increased dietary fibre concentration to levels similar to those used in the present experiments. These results suggest that dehulling may be a necessary step in processing borage seed for use in swine diets. The reduction in feed intake with borage which was apparent throughout the first experiment and during the growing phase of the second experiment can likely be attributed to the presence of pyrrolizine alkaloids in borage (Dobson and Stermitz, 1986). Pyrrolizine alkaloids have been reported to have a bitter taste (Cheeke and Shull, 1985) which may cause animals to limit intake. In addition, these compounds are toxic and have been shown to cause liver damage at high concentrations. Although Larson et al. (1984) suggested that the concentration of pyrrolizine alkaloids in borage is likely too low to cause a significant health hazard, caution should be exercised before including high levels of borage meal in swine diets.
4. Conclusions The results of this study indicate that borage meal has potential for use as a rumen degradable protein supplement for ruminant animals. Relative to four other protein sources selected for their extremes in rumen CP degradability, the effective CP degradability of borage meal was high. Inclusion of borage meal in rations of growing lambs up to 18% of the diet DM, had no adverse effects on intake or nutrient digestibility. In pig rations, borage meal inclusion resulted in reduced intake and poor nutrient utilization especially for growing pigs. The adverse effects of borage meal on pig performance were attributed to bitter taste and to its poor digestibility. References AOAC, 1990. Official Methods of Analysis, ton, DC.
15th edn. Association
of Official Analytical
Chemists,
Washing-
A. F. Must&a et al. /Animal
Feed Science Technology 64 (1997) 273-285
285
Bell, J.M. and Keith, M.O., 1983. Effect of hull and protein contents of barley on protein and energy digestibility and feeding value for pigs. Can. J. Anim. Sci., 63: 201-211. Bell, J.M. and Keith, M.O., 1991. Effect of pig weight and barley hulls on the digestibility of energy, protein, and fibre in wheat, corn and hulless barley diets. Nun. Res., 11: 1307-13 16. Chapkin, R.S. and Carmichael, S.L., 1990. Effects of dietary n-3 and n-6 polyunsaturated fatty acids on macrophage phospholipid classes and subclasses. Lipids, 25: 827-833. Cheeke, P.R. and Shull, L.R., 1985. Natural toxicants in feeds and poisonous plants. AVI Publishing, Westport, CN. Deacon, M.A., De Boer, G. and Kennelly, J.J., 1988. Influence of jet sploding” and extrusion on ruminal and intestinal disappearance of canola and soybeans. J. Dairy Sci., 71: 745-753. Dobson, C.D. and Stermitz, F.R., 1986. Pyrrolizidine alkaloids from borage (Borage qfficinalis) seeds and flowers. J. Nat. Prod., 49: 727-728. Fenton, T.W. and Fenton, M., 1979. An improved method for the determination of chromic oxide in feed and feces. Can. J. Anim. Sci., 59: 631-634. Galwey, N.W. and Shirlin, A.J., 1990. Selection of borage (Borugo offkinalis ) as a seed crop for pharmaceutical uses. Heredity, 65: 249-257. Greenberg, N.A. and Shipe, W.P., 1979. Comparison of the abilities of trichloroactic, picric, sulfosalicylic. and tungstic acids to precipitate protein hydrolysates and proteins. J. Food Sci., 44: 735-737. Kirkpatrick, B.K. and Kennelly, J.J., 1987. In situ degradability of protein and dry matter from single protein sources and from a total diet. J. Anim. Sci., 65: 567-576. Larson, K.M., Roby, M.R. and Stermitz, F.R., 1984. Unsaturated pyrrolizidines from borage (Borage o#icinalis), a common garden herb. J. Nat. Prod., 47: 747-748. McKinnon, J.J., Olubobokun, J.A., Mustafa, A.F., Cohen, R.D.H. and Christensen, D.A. 1995. Influence of dry heat treatment of canola meal on site and extent of nutrient disappearance in ruminants. Anim. Feed Sci. Technol., 56: 243-252. McKinnon, J.J., Olubobokun, J.A., Christensen, D.A. and Cohen, R.D.H., 1991. The influence of heat and chemical treatment on ruminal disappearance of canola meal. Can. J. Anim. Sci., 71: 773-780. Murphy, J.J. and Kennelly, J.J., 1987. Effect of protein concentration and protein source on the degradability of dry matter and protein in situ. J. Dairy Sci., 70: 1841-1849. National Research Council, 1985. Nutrient requirements of sheep. National Academy Press, Washington, DC. National Research Council, 1988. Nutrient requirements of domestic animals. No. 2. Nutrient requirements of swine, 9th edn. NAS-NRC, Washington, DC. 0rskov, E.R. and McDonald, I., 1979. The estimation of protein degradability in the rumen from incubation measurements weighed according to rate of passage. I. Agric. Sci. (Camb.), 92: 499-503. Roe, M.B., Sniffen, C.J. and Chase, L.E., 1990. Techniques for measuring protein fractions in feedstuffs. In: Proc. Cornell Nutr. Conf. Feed Manuf. Cornell Univ., Ithaca, NY p. 81. Statistical Analysis Systems Institute, 1989. SAS/STAT User’s Guide, Version 6, 4th edn, Vol 2. Cary. NC, 846 pp. Steel, R.G. and Torrie, J.H., 1980. Principles and Procedures of Statistics. McGraw-Hill, NY. Van Soest, P.J., Robertson, J.B. and Lewis, B.A., 1991. Methods for dietary fiber, neutral detergent fiber and nonstarch polysaccharides in relation to animal nutrition. J. Dairy Sci., 74: 3583-3597. Zinn, R.A., 1993. Characterization of ruminal and total tract digestion of canola meal and soybean meal in a high-energy for feedlot cattle. J. Anim. Sci., 71: 796-801.
ELSEVIER
Animal Feed Science Technology
64 (1997) 273-285
Effect of borage meal on nutrient digestibility and performance of ruminants and pigs A.F. Mustafa, J.J. McKinnon Department
ofAnimaland
Poultry
*,
P.A. Thacker, D.A. Christensen
Science, 72 Campus Drice,
CJniversi@ of Saskatchewan,
Saskatoon.
Sask..
CanadaS7N5B5
Accepted 22 March 1996
Abstract Borage meal (BM) is derived from the processing of borage (Borage oficinalis) seeds. A series of experiments was conducted to determine the nutritive value of BM as a protein supplement for ruminants and pigs. In situ ruminal effective crude protein degradability (ECPD) was determined for BM relative to four other protein supplements using two ruminally fistulated cows in a randomized complete block design. The protein supplements used for comparsion purposes included two that are high in rumen degradable protein (soybean (SBM) and canola (CM) meals) and two high in rumen undegradable (corn gluten (CGM) and heated canola (HCM) meals) protein. ECPD of borage meal was intermediate to that of the other four protein supplements studied with the following order observed: SBM > CM > BM > HCM > CGM. Voluntary intake (VI) and apparent nutrient digestibility coefficients and digestible energy (DE) content of barley grain and dehydrated alfalfa based diets containing graded levels of BM (0, 6, 12 and 18%) were determined in a completely randomized design using 16 growing lambs. No effect (P > 0.05) of BM inclusion rate was observed on VI, nutrient digestibility coefficients and DE values. In two experiments with swine, BM was included at 0, 10, 20, 30, and 40% in grower diets and 0, 6.75, 13.5, 20.25 and 27% in finisher diets. Both rate and efficiency of gain were depressed in a linear fashion (P < 0.05) as the level of BM in the diet increased. Digestibility coefficients for dry matter, crude protein and gross energy also declined linearly (P < 0.05) as dietary BM increased. It was concluded that BM has potential as a protein supplement for ruminants. However, results of the pig experiments showed poor performance when BM was included in grower and finisher diets. Keyvordsr
Borage meal; Ruminants;
* Corresponding
PII
author.
Copyright SO377-8401(96)01040-1
0377-8401/97/$17.00
Swine; Nutrient utilization
0 1997 Elsevier Science B.V. All rights reserved
274
A.F. Mustafa et al. /Animal Feed Science Technology 64 (1997) 273-285
1. Introduction Borage (Borage o&inalis) is an annual herb, native to the Mediterranean area, but cultivated throughout the world. The plant is used for medicinal purposes as well as for preparing salads and beverages (Larson et al., 1984). The economic importance of borage seed has increased in the last few years because of its high content of gamma linolenic acid (GLA) which is used by the body as a precursor for prostaglandin synthesis (Chapkin and Carmichael, 1990). Borage has an advantage over other sources of GLA, since it is an annual plant with large seeds. These characteristics facilitate harvest and oil extraction. Borage seed has been reported to contain about 32% oil, 24% GLA and 3% erucic acid (Galwey and Shirlin, 1990). Borage meal is produced as a by-product when borage seeds are crushed to obtain their oil. Currently, there is a limited supply of borage meal as there are no commercial crushing plants. However, if the demand for borage oil increases, a concurrent increase in the supply of borage meal will result. Proper utilization of the meal as an animal feed will eventually increase the economic value of the plant as a cash crop. At present, there is very little information on the feeding value of this byproduct for livestock. As such, it is important to examine the nutritive value of borage meal and to report the findings to the livestock industry. The objectives of this study were to determine the chemical composition and rumen degradability characteristics of borage meal and to compare these characteristics to other common protein supplements for ruminants and to determine the voluntary intake (VI) and nutrient digestibility coeficients of borage meal supplemented diets when fed to growing lambs and pigs.
2. Materials and methods 2.1. Rumen in situ incubations 2. I. 1. Chemical composition Borage meal was obtained from PGE, Canada, Ltd., (Saskatoon, Saskatchewan). For comparsion purposes, four additional protein supplements were studied (Table 1). Canola, soybean and corn gluten meals were obtained from a commercial feed mill (Federated Cooperatives Ltd., Saskatoon, Sk., Canada). Heated canola meal was prepared by heating commercially available canola meal to 125°C for 20 min in a vaccum tumble dryer according to the procedure described by McKinnon et al. (1991). The four protein sources used for comparsion purposes were choosen on the basis of their rumen degradability characteristics. Canola and soybean meals are considered good sources of rumen degradable protein (Kirkpatrick and Kennelly, 1987) while heated canola and corn gluten meals are considered good sources of rumen undegradable protein (McKinnon et al., 1995; Murphy and Kennelly, 1987). Samples of the five protein sources were analyzed for dry matter (DM), ash, ether extract (EE), crude protein (CP) and acid detergent lignin according to the methods of the Association of Official Analytical Chemists (AOAC, 1990). Neutral (NDF) and acid (ADF) detergent fibre were analyzed using the method of Van Soest et al. (1991).
A.F. Mustafa et al/Animal Table 1 Chemical
composition
Feed Science Technology 64 (1997) 273-285
21s
of five protein sources used in the rumen in situ trial
Chemical fraction (g kg-’ DM basis)
Ash Ether extract Crude protein (CP) Fiber fractions Neutral detergent fibre Acid detergent fibre Acid detergent lignin Protein fractions (g kg -’ of CP) Soluble CP Non-protein nitrogen Neutral detergent insoluble CP Acid detergent insoluble CP Degradable CP
Protein source Borage meal
Soybean meal
canola meal
Heated canola meal
Corn gluten meal
137 71 334
66 16 494
74 58 406
76 57 381
23 10 627
350 227 65
125 44 5
327 198 76
507 223 137
138 107 10
232 215 189 102 654
112 52 24 17 716
324 264 159 55 639
88 89 557 110 327
6 6 47 44 69
Neutral and acid detergent insoluble nitrogen were determined on NDF and ADF residues, respectively, using the Kjeldahl method (AOAC, 1990). The mineral composition of borage meal was determined following digestion with a perchloric-nitric acid mixture (AOAC, 1990) using a Pet-kin-Elmer Mode1 5000 atomic absorption spectrophotometer (Technicon GTPC autoanalyzer II>. Phosphorus content was determined colorimetericaly (Pharmacia LKB utraspec III). For the five protein sources, in vitro protein solubility and degradability were determined following the procedures of Roe et al., 1990. For protein solubility, duplicate samples (0.5 g) were weighed into 125 ml Erlenmeyer flasks. Samples were incubated in 50 ml of borate-phosphate buffer (pH 6.7) for 1 h at 39°C. Protein degradability was estimated by weighing duplicate samples (0.2 g air dry protein) into Erlenmeyer flasks. The samples were soaked in 40 ml of borate-phosphate buffer and incubated for 1 h at 39°C. Following incubation, 10 ml of fresh protease solution (protease type XIV from Streptom.yces griseus, Sigma Chemical Co., St. Louis, MO) was added to each flask and the solution incubated at 39°C for 18 h. The insoluble residues were filtered through Whatman # 54 filter paper and residual nitrogen determined using the Kjeldahl method (AOAC, 1990). Protein solubility and degradability were expressed as percent of total protein (N X 6.25). Non-protein nitrogen was determined by precipitating true protein using sodium tungstate as a precipitating agent (Greenberg and Shipe, 1979).
2.1.2. Rumen incubations Rumen CP kinetic parameters and effective degradabilities of the five protein supplements were determined using two non-lactating Holstein cows fitted with flexible rumen fistulae. The cows were fed a 50:50 barley si1age:barley concentrate diet (DM basis), twice daily (08.00 and 16.00 h) at 1.5% of body weight (DM basis). The
276
A.F. Mustafa et al. /Animal
Feed Science Technology 64 (1997) 273-285
Table 2 In situ rumen crude protein (CP) kinetic parameters
and effective degradability
of five protein sources
Protein source
S.E.M. 4
Borage meal
Soybean meal
Canola
Heated
meal
canola meal
Corn gluten meal
31.9 x 45.4 w 9.8 ’ 61.7 ’
11.7 88.3 10.3 71.2
29.8 y 70.2 ’ 6.0 y 68.0 y
12.5 ’ 86.6 y 1.4 L 34.3 w
2.3 NJ’ 97.7 x 0.5 L 11.2 ”
Protein kinetic parameters ’ Soluble fraction (%) Potentially degradable fraction (%) Degradation rate (% h-‘) Effective degradability (%) *
z y x ’
0.44 1.44 0.37 0.85
’ Derived from the equation of Brskov and McDonald (1979): a + b * (I-Ed”), where a is soluble fraction, is degradable fraction and c is rate of degradation of b fraction. * Calculated assuming rumen flow rate of 5% h-’ ’ x, y, z, w, v Means in the same row with different superscripts differ (P < 0.05). 4 S.E.M = Standard error of the mean.
b
concentrate consisted of 74.5% barley, 17% canola meal, 2% corn gluten meal, 2% molasses, 0.5% canola oil, 0.6% dicalcium phosphate, 0.3% cobalt-iodized salt, 0.1% ground limestone and 3% mineral-vitamin mix. Analysis of the diet indicated the following nutrient profile: 17.7% CP; 41.2% NDF; 21.0% ADF; 0.8% calcium (Ca); and 0.7% phosphorus (P>. The in situ rumen incubation consisted of six time periods. These included 2, 4, 6, 8, 12 and 24 h following the morning feeding. Duplicate samples (7 g> of each meal were placed in nylon bags (9 X 21 cm; 41 pm porosity) and incubated in the rumen of each cow at the specified time period. The bags were inserted for the specified times and removed together from the rumen at the completion of the incubation. Following removal from the rumen, the bags were washed and handled as described by McKinnon et al. (1991). Ruminal CP disappearance at each incubation time was calculated from the CP content of the original samples and the residues following rumen incubation. Ruminal CP disappearance data was utilized to estimate ruminal CP kinetic parameters (Table 2) using the equation of 0rskov and McDonald (1979): P=a+b*(l
-epC’)
where P is CP disappearance at time t, a is the rapidly soluble CP fraction (%), b is the insoluble but degradable CP fraction (%) and c is the rate constant at which b is degraded (% h- ’>. The constants a, b and c were estimated by an iterative least-square method using the nonlinear regression procedure of the Statistical Analysis Systems Institute (1989) with the constraint that a + b I 100. Effective ruminal CP degradability (ECPD) of each protein supplement at a 5% rumen flow rate (k) was estimated using the equation of 0rskov and McDonald (1979): ECPD=a+b*c/(c+k) where a,
b
and c are defined as above.
A.F.
Table 3 Ingredients
Mustafa et al. /Animal
and chemical
composition
Feed Science Technology 64 (1997) 273-285
of borage supplemented
211
diets used in the sheep trial
Borage meal inclusion rate (“/c of diet) 0 Ingredient (% DM basis) Barley 54.0 Dehydrated alfalfa meal 41.0 Borage meal 0.0 Molssas 2.0 Salt 2.0 Mineral supplement a 1.0 Chemical composition (g kg-’ DM basis) Ash 78 Crude protein 151 Acid detergtent tibre 147 Calcium IO Phosphorous 3 Gross energy (MJ kg-’ )
18.0
6
12
18
54.0 35.0 6.0 2.0 2.0 1.0
54.0 29.0 12.0 2.0 2.0 1.0
54.0 23.0
79 170 157 3
80 178 158 10 4
81 186 160 10 4
18.0
18.0
18.4
I
18.0 2.0 2.0 1.0
AContained 16% Ca, 16% P, 1500 mg kg-’ Zn, 25 mg kg-’ I, 100 mg kg-’ Fe, 640 mg kg-’ Mn. 14 mg kg~’ Co. 3000 mg kg-’ F, 151,800 IU kg-’ vitamin A, 15,181 IU kg-’ vitamin D, 500 IU kg-’ vitamin E.
2.2. Voluntary intake (VI) and total tract digestibility
studies
2.2.1. Sheep trial Voluntary intake and nutrient digestibility of diets formulated with graded levels of borage meal were determined using 16 growing ram lambs (39.8 + 3.0 kg). The animals were housed in individual metabolism crates and were fed one of four experimental diets. The control diet contained dehydrated alfalfa meal as a supplemental protein source. In Diets 2, 3 and 4, borage meal replaced dehydrated alfalfa meal at 6, 12 and 18% substitution levels (Table 3). The chemical composition and gross energy (GE) content of the experimental diets are shown in Table 3. Crude protein and ADF levels increased with borage meal inclusion rate. However, all diets met CP requirements for growing and finishing lambs (National Research Council, 1985). All diets were pelleted (4.8 mm diameter) and offered twice daily in equal portions at 08.00 and 15.00 h. The protocol of the digestibility trial consisted of a 7 day adaptation period, seven days to determine voluntary intake (VI), three days of restricted intake (85% of VI) and a 5 day total faecal collection period. Faeces were collected once daily, subsampled (10% of total faecal output) and dried in a forced air oven at 65°C for 72 h. Faecal samples were cornposited by animal over the 5 day collection period. Feed samples were collected simultaneously and dried in a similar manner to faecal samples. Feed and faecal samples were ground in a Christi-Norris mill (1.0 mm screen) and stored for chemical analyses. Feed and faecal samples were analyzed for DM, ash, CP and ADF as described above. Gross energy (GE) content was determined on dried feed and faecal samples using an adiabatic oxygen bomb calorimeter. Apparent nutrient digestion coefficients (Table 4) were calculated as the difference between nutrient intake and excretion in fecal material and expressed as a percentage of intake.
278
A.F. Mustafa et al. /Animal
Table 4 Effect of borage meal inclusion
Feed Science Technology 64 (1997) 273-285
rate on voluntary
Parameter
intake and nutrient digestibility
Borage meal inclusion rate (% of diet)
Intake Dry matter (% BW ‘1 Dry matter intake (g kg BW-“-75) Digestibility coeffwients (o/o) Dry matter Organic matter Crude protein Acid detergent libre Gross energy Digestible energy (h4J kg”)
0
6
12
18
4.5 114.2
4.2 105.9
4.6 118.0
4.6 116.5
0.20 5.39
71.2 72.4 70.8 31.3 68.2 12.6
69.5 70.8 70.3 28.5 67.4 11.6
70.4 71.9 71.9 28.2 68.5 12.7
70.1 71.9 70.3 27.4 68.3 12.7
1.35 1.28 1.52 2.75 1.63 0.29
a Polynomial contrast indicated linear CL), quadratic b S.E.M. = Pooled standard error of the mean. ’ BW = body weight.
of diets fed to sheep
S.E.M. b
Contrast a
L
Q
C
NS NS NS NS NS NS NS NS NS
NS NS NS NS NS NS NS NS NS
NS NS NS NS NS NS NS NS NS
(Q), or cubic (C) effect (NS = not significant
at P = 0.05).
2.2.2. Pig trials 2.2.2.1. Experiment 1. Sixty female crossbred pigs (Yorkshire X Landrace) weighing an average of 22.2 & 0.4 kg were assigned on the basis of weight and litter to one of five barley-soybean meal based diets. During the growing period (22 to 65 kg), the diets contained 0, 10, 20, 30 or 40% borage meal while during the finishing period (65 to 83 kg) the diets contained 0, 6.8, 13.5, 20.3 or 27.0% borage meal (Table 5). The diets contained 176 g kg-’ CP and 8.5 g kg- ’ lysine in the growing period (22 to 65 kg) and
Table 5 Formulation
of diets to determine
the effects of graded levels of borage meal on pig performance Finishing period
Growing period Level of borage meal (W) 0 Form&ion of diets (% as fed) Barley 78.40 Soybean meal 17.15 Borage meal Tallow 0.80 Dicalcium phosphate 1.75 Limestone 1.15 Salt (iodized) 0.50 Vitamin-mineral premix a 0.25 Synthetic lysine
Level of borage meal (%)
10
20
30
40
0
6.75
13.50
20.25
27.00
70.92 12.80 10.00 3.10 1.60 0.80 0.50 0.25 0.03
63.45 8.40 20.00 5.45 1.45 0.42 0.50 0.25 0.08
55.99 4.00 30.00 7.80 1.30 0.03 0.50 0.25 0.13
48.10
83.15 11.70 1.30 1.82 1.15 0.50 0.25 0.12
77.75 8.80 6.75 2.90 1.70 1.20 0.50 0.25 0.15
72.30 5.95 13.50 4.42 1.65 1.25 0.50 0.25 0.18
66.84 3.10 20.25 6.00 1.55 1.30 0.50 0.25 0.21
61.55
40.00 9.80 1.17 0.50 0.25 0.18
27.00 7.60 1.45 1.40 0.50 0.25 0.25
a Supplied per kg of diet: 4125 I.U. vitamin A; 275 I.U. vitamin D3; 13.5 I.U. vitamin E; 2 mg vitamin K, 1 mg thiamin; 4 mg riboflavin; 22 mg niacin; 16.5 mg pantothenic acid; 14 ug vitamin B-12; 250 mg choline chloride; 0.12 mg biotin; 3 mg copper; 40 mg iron; 21.3 mg manganese; 76.5 mg zinc; 0.05 mg selenium.
A.F. Mustafa et al. /Animal Feed Science Technology 64 (19971273-285 Table 6 Chemical composition
(g kg-’ % as fed) of diets fed to growing/finishing
219
pigs to determine the nutritive value
of graded levels of borage meal Growing period
Finishing period
Level of borage meal (%) ’
Level of borage meal (%) a
0
10
20
30
JO
0
6.15
13.50
20.25
27
115.6 175.1 54.3 22.0 65.4
110.7 172.9 58.0 48.7 90.6
111.9 180.1 64.0 73.4 107.1
110.7 175.4 69.6 98.1 132.2
112.6 178.3 74.4 117.1 151.5
81.1 168.7 53.1 41.0 63.0
7.93 169.0 53.6 50.8 79.9
87.6 167.8 59.4 61.8 94.1
85.5 168.5 64. I 78.8 103.0
81.2 167.5 68.3 96.6 128.9
129.4 179.4 54.4 29.7 54.6
124.1 176.7 56.5 54.9 75.2
123.8 176.9 61.6 76.3 105.5
121.7 176.5 65.8 95.6 130.8
121.3 180.8 71.3 119.1 148.5
117.5 163.3 54.4 31.9 59.2
122.6 160.8 59.1 47.5 85.0
115.3 160.8 66.0 62.0 101.3
113.7 163.9 73.9 82.1 126.3
110.5 160.0 78.4 96.1 135.9
Experiment I Moisture Crude Protein Ash Ether extract Acid detergent fibre Experiment 2 Moisture Crude Protein Ash Ether extract Acid detergent fibre a % as fed.
167 g kg-' CP in the finishing phase (65 to 83 kg) (Table 6). Tallow was added to keep the diets isocaloric while additional lysine was added to compensate for the low lysine level of borage meal relative to soybean meal (Table 7). All other essential amino acids, vitamins and minerals were present in sufficient amounts to meet or exceed the requirements recommended by the National Research Council (1988). The diets were pelleted (low pressure steam) with the temperature in the conditioning chamber maintained below 60°C.
Table 7 Essential amino acid composition
(g kg-’ as fed) of diets fed to growing/finishing
pigs in experiment
SBM ’
0
10
20
30
40
0
6.75
13.50
20.25
27.00
Arginine Histidine Isoleucine Leucine Lysine
23.9 7.7 10.3 16.9 11.0
30.7 11.1 18.0 32.7 28.3
11.3 4.4 6.3 12.3 8.7
12.0 4.3 6.1 11.5 8.6
12.8 4.4 6.2 11.5 8.7
13.4 4.0 6.0 10.5 8.4
13.7 4.1 6.0 10.3 8.4
10.3 4.0 5.8 11.4 8.6
10.4 3.9 5.6 11.0 8.6
10.6 3.8 5.4 10.3 8.2
10.9 3.8 5.4 10.0 8.4
3.1 5.2 9.6 7.9
Methionine Phenylalanine Threonine Valine
1.6 10.7 9.1
6.2 21.7 17.0 18.6
2.1 8.2 6.2 7.6
2.8 7.7 6.0 7.4
2.3 7.7 6.1 7.5
2.0 6.8 5.7 7.0
2.0 6.8 5.7 7.0
2.2 7.7 5.8 7.3
2.0 7.4 5.7 7.1
2.6 7.1 5.4 6.9
2.0 6.8 5.4 6.7
2.6 6.5 5.1 6.4
a % as fed. h soybean meal
11.2
Growing period
Finishing period
Level of borage meal (%I a
Level of borage meal (%c) ’
1
Borage meal
11.2
280
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The pigs were housed four to a pen in concrete pens measuring 2.7 X 3.6 m. The pens were equipped with four self feeders. The pigs were allowed individual access to their specific self-feeder for 30 min, twice daily. The pigs were weighed at weekly intervals. Feed consumption was determined on an individual basis at the time of weighing. The trial was run for 84 days and concluded when the pigs reached an average weight of 83.2 f 1.1 kg. One pig experienced a gastric ulcer while on the test and was removed from the experiment. Digestibility coefficients for DM, CP and GE were determined using 20 pigs from the growth trial, starting at an average weight of 37.9 f 1.1 kg. The pigs were housed under identical conditions and fed the same diets as those used during the growing stage, modified only by the addition of 0.5% chromic oxide as a digestibility indicator. The chromic oxide containing diets were fed for 10 days, with an eight day adaptation period followed by two days of faecal collection. Faeces were collected twice daily, immediately following feeding, by driving the pigs to a clean room where freshly voided feces were obtained. Faecal samples were then frozen. Prior to analysis, the frozen faeces were placed in a forced-air oven and dried for 48 h at 66°C and then ground (1 mm screen). Samples of feed and faeces were analyzed for DM, CP, ash, EE and ADF according to the methods of the AOAC (1990). Gross energy was determined with an adiabatic oxygen bomb calorimeter. Amino acid analysis of the borage and soybean meals and the grower diets were carried out using a Perkin-Elmer Series 4 Liquid Chromatograph following hydrolysis for 22 h with 6 N HCl. Chromic oxide was determined by the method of Fenton and Fenton (1979). 2.2.2.2. Experiment 2. Twenty barrows and 40 gilts (Yorkshire X Landrace) obtained from the same source as those in the previous trial, weighing an average of 28.0 f 0.5 kg were assigned on the basis of sex, weight and litter to one of the same dietary treatments used in the first swine trial. The diets averaged 178 and 162 g kg-’ CP during the growing (27.5 to 53.5 kg) and finishing (53.5 to 84.6 kg) periods, respectively (Table 6). All esential vitamins and minerals were present in sufficient amounts to meet or exceed requirements as recommended by the National Research Council (1988). Pigs were housed and fed in a similar manner to that described for Experiment 1. All diets were pelleted as described for Experiment 1. The trial was run for 70 days and terminated when the pigs reached an average weight of 87.0 k 1.2 kg. One pig died during the experiment from a twisted gut. 2.2.3. Statistical analysis Statistical analysis was carried out using the General Linear Model procedure of Statistical Analysis Systems Institute (1989). Data from the rumen in situ trial was analyzed as a randomized complete block design with the two cows serving as blocks. Where appropriate, means were separated using the Student-Neuman-Keuls procedure (Steel and Torrie, 1980). Data from the sheep trial were analyzed as a completely randomized design (four treatments and four replicates). The data in Experiment 1 of the pig trial was analyzed as a one way analysis of variance while Experiment 2 was analyzed as a 2 X 5 factorial with sex, treatment and their interaction being accounted
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Feed Science Technology 64 ClYY7l273-285
781
for in the model. Polynomial contrasts (linear, quadratic and cubic) were used to test the effect of borage meal inclusion rate on feed intake and nutrient digestibilities in the sheep and pig trials (Steel and Torrie, 1980).
3. Results and discussion
3.1. In situ incubations 3. I. I. Chemical composition The borage meal and the four other protein sources were sampled from a single batch of each meal. It is thus not possible to analyze the chemical composition data statistically. However, to the author’s knowledge, little information exists in the literature for borage meal. Therefore, it is of interest to compare its chemical composition to that of the other protein sources used in the study. Borage meal had the following mineral profile: 18.1, 9.8, 6.3, 1.3, and 17.4 (g kg-‘) calcium, phosphorus, magnesium, sodium and potassium, respectively. Trace mineral levels were 23.3, 73.5, 269.4 and 159.1 mg kg-‘, respectively, for copper, zinc, iron and manganese. Total ash content averaged 137 g kg-’ for borage meal. This value was 85.1, 107.8 and 495.7% higher than those for canola, soybean and corn gluten meals, respectively (Table 1). The ether extract content (g kg-’ ) of borage meal (71) was comparable with that of canola meal (58) but higher than that of soybean (16) and corn gluten meal (10) (Table 1). Comparsion of the neutral (NDF) and acid (ADF) detergent fibre levels of borage meal relative to the other four protein sources indicated that this protein source had a lower NDF content than heated canola meal, comparable with canola meal and higher than soybean and corn gluten meals. ADF levels were highest for borage meal, intermediate for canola and heated canola meals and lowest for soybean and corn gluten meals. The CP content of borage meal (334 g kg-‘) was 33.1, 17.7, 12.3 and 46.7% lower than soybean meal, canola meal, heated canola meal and corn gluten meal, respectively (Table 1). Acid and neutral detergent insoluble protein levels followed a similar pattern to NDF and ADF levels (Table 1). 3.1.2. In situ incubation Fitting the CP disappearance data to the Orskov and McDonald (1979) equation indicated that borage meal had the highest (P < 0.05) soluble (a value) and the lowest (P < 0.05) potentially degradable CP (b value) fraction (Table 2). Rapidly soluble CP fraction followed the order (P < 0.05): borage meal > canola meal > soybean meal = heated canola meal > corn gluten meal (Table 2). The results of the in situ trial agree well with the chemical characterization of the CP content of the five meals which indicated that borage and canola meals had the highest soluble protein content followed by soybean meal, heated canola meal and corn gluten meal (Table 1). The relative soluble CP levels of canola and soybean meals found in this study agree with those of Zinn (1993) and Kirkpatrick and Kennelly (1987). Potentially degradable CP fraction followed the order (P < 0.05): corn gluten meal > heated canola meal = soybean meal > canola meal > borage meal, respectively while the rate (c value) of CP degradation
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was highest (P < 0.05) for borage and soybean meals, followed by canola meal, and was lowest (P < 0.05) for heated canola and corn gluten meals (Table 2). The relatively low potentially degradable CP fraction of borage meal can be attributed to its high soluble CP and acid detergent insoluble protein contents (Table 1). Effective CP degradability of borage meal was lower (P < 0.05) than soybean and canola meals and higher (P < 0.05) than that of heated canola and corn gluten meals. Effective CP degradability was higher (P < 0.05) in soybean meal than canola meal and was higher (P < 0.05) in heated canola meal than corn gluten meal. Again the results of the in situ incubation are in good agreement with the chemical data. Results of the in vitro protease technique indicated that the degradable CP content was highest for soybean meal, followed by borage and canola meals and finally by the two rumen escape protein sources (Table 1). The results of the in situ study are also in good agreement with those of other researchers (Deacon et al., 1988 and Kirkpatrick and Kennelly, 1987) who have shown that soybean and canola meals are highly degraded in the rumen and thus poor sources of rumen undegradable protein. On the other hand, heated canola and corn gluten meals have been shown to be good sources of rumen undegradable protein (Murphy and Kennelly, 1987; McKinnon et al., 1995). Since the ECPD of borage meal was only 9.3% lower than canola meal and 79.9% higher than that of heated canola meal, one would classify borage meal as a relatively highly degradable protein source for ruminants. 3.2. Voluntary intake and total tract digestibility
studies
3.2.1. Sheep trial Incorporation of borage meal up to 18% of the diet had no effect on voluntary DM matter intake expressed as a percentage of body weight, which averaged 4.5 f 0.19% (range 4.2-4.60/ o) across treatments (Table 4). Similarly, no differences in intake were found when expressed on a metabolic body weight basis (Table 4). Nutrient digestibility coefficients for DM, OM, CP, and ADF were not influenced by borage inclusion level (Table 4). Consequently, DE values (MJ kg-’ DM) were similar across the four experimental diets (Table 4). These results indicate that inclusion of borage meal up to 18% of a barley grain and dehydrated alfalfa meal based diet had no effect on DM intake or apparent nutrient digestibility by growing lambs. 3.2.2. Pig trial In the first pig experiment, average daily gain was depressed in a linear (P < 0.05) manner as the inclusion level of borage meal in the diet increased (Table 8). The depression in growth appeared to result from depressed feed intake, particularly at the higher levels of borage meal inclusion. Feed efficiency was not significantly different between treatments but tended to be poorer as the level of borage meal in the diet increased, although the diet with the highest level was used fairly efficiently during the finishing period (Table 8). This is likely a reflection of the increased ability of pigs to degrade fibre as they mature (Bell and Keith, 1991). Digestibility coefficients for DM, CP and GE all declined in a linear fashion (P < 0.05) as the level of borage meal in the diet increased.
A.F. Mustafa et al./Animal
Feed Science Technology 64 (1997) 273-285
Table 8 Effect of graded levels of borage meal on pig performance
(Experiment
Level of borage meal (%) Grower period Finisher period
0.00 0.00
10.00 6.15
Growing Period (22-6.5 kg) Daily gain (kg) 0.12 0.73 Daily feed (kg) 1.74 1.86 Feed efficiency 2.41 2.52 Finishing Period (65-83 kg) Daily gain (kg) 0.90 0.89 Daily feed (kg) 2.62 2.70 Feed efficiency 2.91 3.03 Entire Experiment (22-83 kg) Daily gain (kg) 0.77 0.77 Daily feed (kg) 1.96 2.07 Feed efficiency 2.55 2.67 Digestibility % Dry matter 72.5 67.5 Crude protein 76.3 68.2 Gross energy 72.2 68.2
Q
C
0.03 0.07 0.06
0.007 0.052 NS
NS NS NS
NS NS NS
0.85 2.43 2.87
0.04 0.10 0.12
NS 0.019 NS
NS NS NS
NS NS NS
2.71
0.69 1.82 2.63
0.03 0.07 0.05
0.003 0.027 NS
NS NS NS
NS NS NS
60.0 64.3 64.5
61.9 62.4 66.9
1.87 1.58 1.69
0.0002 0.0001 0.018
NS 0.0052 NS
NS NS NS
30.00 20.25
40.00 27.00
0.69 1.73 2.52
0.65 1.65 2.56
0.64 1.62 2.57
0.84 2.47 3.07
0.75 2.32 3.12
0.72 1.91 2.65
0.67
64.0 65.4 66.5
1.82
Level of borage meal (%) 10.00 6.75
20.00 13.50
Growing Period (28-54 kg) Daily gain (kg) 0.82 0.79 0.77 Daily feed (kg) 1.76 1.77 1.79 Feed efficiency 2.12 2.24 2.32 Finishing Period (54-87 kg) Daily gain (kg) 0.94 0.98 0.96 Daily feed (kg) 2.73 2.84 2.79 Feed efficiency 2.92 2.92 2.92 Entire Experiment (28-87 kg) Daily gain (kg) 0.88 0.88 0.87 Daily feed (kg) 2.24 2.30 2.29 Feed efficiency 2.55 2.61 2.65
Contrast a L
20.00 13.50
(Q) or cubic
Table 9 Effect of graded levels of borage meal on pig performance
0.00 0.00
1)
S.E.M. b
’ Polynomial contrast indicated linear (L), quadratic P = 0.05). b S.E.M. = Pooled standard error of the mean,
Grower period Finisher period
283
(C) effects
(Experiment
S.E.M. s Contrast
(NS = not significant
2)
’
Barrows 2 Gilts
S.E.M. ’
L
Q
0.02 0.06 0.04
0.0001 0.039 0.0001
NS NS 0.77 NS NS 1.74 NS NS 2.30
0.76 1.73 2.27
0.87 2.60 3.00
0.04 0.09 0.07
NS NS NS
NS NS 1.03 a NS NS 3.00 a NS NS 2.92
0.89 b 0.03 2.62 b 0.06 2.97 0.05
0.77 2.12 2.75
0.03 0.07 0.05
0.005 NS 0.016
NS NS 0.89 a NS NS 2.37 a NS NS 2.64
0.82 b 0.02 2.18 b 0.05 2.66 0.03
30.00 20.25
40.00 27.00
0.75 1.72 2.31
0.67 1.64 2.44
0.93 2.78 3.01 0.84 2.25 2.69
at
C
0.02 0.04 0.03
’Polynomial contrast indicated linear CL), quadratic (Q) or cubic (C) effects (NS = not significant P = 0.05). ’ a, b Means in the row within sex with different superscripts are different (P < 0.05). ’ S.E.M. = Pooled standard error of the mean.
at
284
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In the second experiment, rate and efficiency of gain of the pigs were also depressed in a linear fashion (P < 0.05) as the level of borage meal in the diet increased (Table 9). However, in this experiment, feed intake was only significantly affected during the growing period (28-54 kg) and only at the highest level of inclusion (40%). As expected, barrows gained faster (P < 0.05) and consumed more (P < 0.05) feed than gilts over the entire experiment. In formulating the diets for the pig experiment, an attempt was made to compensate for the known anti-nutritional shortcomings of borage meal. Since the proximate analysis (Table 1) revealed a considerably higher fibre and ash concentration in borage meal compared with soybean meal, tallow was added to the borage meal containing diets as a mean of increasing their energy content. Similarly, synthetic lysine was added to the borage meal containing diets to bring their lysine concentration up to that of the soybean meal control diet (Table 7). Despite this effort, borage meal containing diets failed to support a level of performance similar to that of pigs fed soybean meal, indicating impaired utilization of nutrients. Bell and Keith (1983) reported reductions in the digestibility of dry matter, crude protein and energy as they increased dietary fibre concentration to levels similar to those used in the present experiments. These results suggest that dehulling may be a necessary step in processing borage seed for use in swine diets. The reduction in feed intake with borage which was apparent throughout the first experiment and during the growing phase of the second experiment can likely be attributed to the presence of pyrrolizine alkaloids in borage (Dobson and Stermitz, 1986). Pyrrolizine alkaloids have been reported to have a bitter taste (Cheeke and Shull, 1985) which may cause animals to limit intake. In addition, these compounds are toxic and have been shown to cause liver damage at high concentrations. Although Larson et al. (1984) suggested that the concentration of pyrrolizine alkaloids in borage is likely too low to cause a significant health hazard, caution should be exercised before including high levels of borage meal in swine diets.
4. Conclusions The results of this study indicate that borage meal has potential for use as a rumen degradable protein supplement for ruminant animals. Relative to four other protein sources selected for their extremes in rumen CP degradability, the effective CP degradability of borage meal was high. Inclusion of borage meal in rations of growing lambs up to 18% of the diet DM, had no adverse effects on intake or nutrient digestibility. In pig rations, borage meal inclusion resulted in reduced intake and poor nutrient utilization especially for growing pigs. The adverse effects of borage meal on pig performance were attributed to bitter taste and to its poor digestibility. References AOAC, 1990. Official Methods of Analysis, ton, DC.
15th edn. Association
of Official Analytical
Chemists,
Washing-
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Bell, J.M. and Keith, M.O., 1983. Effect of hull and protein contents of barley on protein and energy digestibility and feeding value for pigs. Can. J. Anim. Sci., 63: 201-211. Bell, J.M. and Keith, M.O., 1991. Effect of pig weight and barley hulls on the digestibility of energy, protein, and fibre in wheat, corn and hulless barley diets. Nun. Res., 11: 1307-13 16. Chapkin, R.S. and Carmichael, S.L., 1990. Effects of dietary n-3 and n-6 polyunsaturated fatty acids on macrophage phospholipid classes and subclasses. Lipids, 25: 827-833. Cheeke, P.R. and Shull, L.R., 1985. Natural toxicants in feeds and poisonous plants. AVI Publishing, Westport, CN. Deacon, M.A., De Boer, G. and Kennelly, J.J., 1988. Influence of jet sploding” and extrusion on ruminal and intestinal disappearance of canola and soybeans. J. Dairy Sci., 71: 745-753. Dobson, C.D. and Stermitz, F.R., 1986. Pyrrolizidine alkaloids from borage (Borage qfficinalis) seeds and flowers. J. Nat. Prod., 49: 727-728. Fenton, T.W. and Fenton, M., 1979. An improved method for the determination of chromic oxide in feed and feces. Can. J. Anim. Sci., 59: 631-634. Galwey, N.W. and Shirlin, A.J., 1990. Selection of borage (Borugo offkinalis ) as a seed crop for pharmaceutical uses. Heredity, 65: 249-257. Greenberg, N.A. and Shipe, W.P., 1979. Comparison of the abilities of trichloroactic, picric, sulfosalicylic. and tungstic acids to precipitate protein hydrolysates and proteins. J. Food Sci., 44: 735-737. Kirkpatrick, B.K. and Kennelly, J.J., 1987. In situ degradability of protein and dry matter from single protein sources and from a total diet. J. Anim. Sci., 65: 567-576. Larson, K.M., Roby, M.R. and Stermitz, F.R., 1984. Unsaturated pyrrolizidines from borage (Borage o#icinalis), a common garden herb. J. Nat. Prod., 47: 747-748. McKinnon, J.J., Olubobokun, J.A., Mustafa, A.F., Cohen, R.D.H. and Christensen, D.A. 1995. Influence of dry heat treatment of canola meal on site and extent of nutrient disappearance in ruminants. Anim. Feed Sci. Technol., 56: 243-252. McKinnon, J.J., Olubobokun, J.A., Christensen, D.A. and Cohen, R.D.H., 1991. The influence of heat and chemical treatment on ruminal disappearance of canola meal. Can. J. Anim. Sci., 71: 773-780. Murphy, J.J. and Kennelly, J.J., 1987. Effect of protein concentration and protein source on the degradability of dry matter and protein in situ. J. Dairy Sci., 70: 1841-1849. National Research Council, 1985. Nutrient requirements of sheep. National Academy Press, Washington, DC. National Research Council, 1988. Nutrient requirements of domestic animals. No. 2. Nutrient requirements of swine, 9th edn. NAS-NRC, Washington, DC. 0rskov, E.R. and McDonald, I., 1979. The estimation of protein degradability in the rumen from incubation measurements weighed according to rate of passage. I. Agric. Sci. (Camb.), 92: 499-503. Roe, M.B., Sniffen, C.J. and Chase, L.E., 1990. Techniques for measuring protein fractions in feedstuffs. In: Proc. Cornell Nutr. Conf. Feed Manuf. Cornell Univ., Ithaca, NY p. 81. Statistical Analysis Systems Institute, 1989. SAS/STAT User’s Guide, Version 6, 4th edn, Vol 2. Cary. NC, 846 pp. Steel, R.G. and Torrie, J.H., 1980. Principles and Procedures of Statistics. McGraw-Hill, NY. Van Soest, P.J., Robertson, J.B. and Lewis, B.A., 1991. Methods for dietary fiber, neutral detergent fiber and nonstarch polysaccharides in relation to animal nutrition. J. Dairy Sci., 74: 3583-3597. Zinn, R.A., 1993. Characterization of ruminal and total tract digestion of canola meal and soybean meal in a high-energy for feedlot cattle. J. Anim. Sci., 71: 796-801.