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Effects of Cubing Alfalfa Hay on Development of Yearling Beef Heifers and In Situ Rate and Extent of Disappearance12
The Professional Animal Scientist 11 :30-34
Effects of Cubing Alfalfa Hay on Development of Yearling Beef Heifers and In Situ Rate and Extent ofnic~nno~r~nrol,2 ...., hl",.4t-'t-'~UI UI I~~ R. P. ANSOTEGUI, E.
J. SWENSSON, M. W. TESS, K. S. BRYAN, C. K. CLARK,
and R. M. BROWNSON, PAS Montana State University, Bozeman, MT 59717
Abstract The objective of this study was to evaluate the effects of cubing alfalfa on heifer development and in situ rumina I NDF and CP disappearance. One hundred ninety-two prepuberal crossbred heifers were allotted to 16 pens with each pen randomly allotted to treatment; 1) cubed alfalfa (CA) or 2) long alfalfa (LA). Diets were consumed ad libitum. Heifers were weighed every 28 d throughout the 96-d trial. Following synchronization, heifers were bred by AI 12 h after observed estrus. Hay intake by CA heifers was lower (p<.05) than LA heifers (11.6vs 13.5 kgper head per d), butADG was faster (P<. 05) for CA heifers than those fed LA (1.35 vs 1.03 kgper head per d). Feed per kilogram ofgain was lower (p<.05) for heifers fed CA than for heifers fed LA (8.6 vs 13.2 kg:kg). No differences were observed in number ofheifers bred AI (P>.25) or in total pregnancy (p>.25). Six mature beefcows fitted with ruminal cannula were used in a switchback design to determine influence ofcubing on in situ ruminal CP and NDF disappearance.
During each period animals consumed their respective diets ad libitum for 14 d of adaptation and 5 d ofdata collection. Nylon bags containing 5-g samples of either CA or LA were ruminally incubated for 12,24,36,48,72, and 96 h. Bag residues were analyzed for DM, Cp, and NDF content. The DM and NDF disappearance rate constants and extent ofDM disappearance for CA (.27, .11, and 79.6%, respectively) were higher (p<.04) than LA (.16, .08, and 68.1%, respectively). Crude protein rate constants were similar (p>.05) forCA (.33) and LA (.28). Results from the heifer development trial suggest that heifers fed CA gained faster and were more efficient than heifers fed LA. No differences were detected in reproductive performance, possibly because all heifers reached the recommended weight for puberty at the beginning of the breeding season regardless of treatment (average, 409 kg). Results from the in situ trial indicate ruminal DM and NDF disappearance were enhanced by cubing alfalfa, but not rate of CP disappearance. (Key Words: Beef Heifers, Puberty, Alfalfa Cubes.)
1 Mont. Agric. Exp. Sta. J. Series Number J-3008. 2The authors gratefully acknowledge High The effects of changing the physiMountain Ranches, Dell, MT for supporting this research. cal form of long-stem hay on growth
Introduction
Reviewed by N. A. Cole and T. W. White.
and feed intake have been studied in
growing-finishing cattle. Compared with long hay, cubing alfalfa has been shown to be advantageous due to increased ease of transport, storage, and feeding, plus reduced feed waste (2,9). Cubing has been shown to improve daily gain (11) and feed intake and conversion (6, 7). Butcher et al. (3) found that cattle consume more cubed hay than baled hay, resulting in increased weight gain. Cubing alfalfa hay has been reported to increase DM and CP digestibility while reducing retention time in the rumen when compared with baled alfalfa (13). However, other researchers have reported that chopped or baled alfalfa hay is more digestible than cubed hay (8, 12). Few studies have been conducted to evaluate the effects of cubing hay on reproductive performance in replacement heifers. Because the greatest advantages to feeding cubed hay have been seen in growing cattle fed high roughage diets, it was hypothesized that cubing high quality hay might also improve reproductive development of replacement heifers. The objectives of this study were to evaluate effects of cubing alfalfa hay on development and reproductive performance of yearling beef heifers and to determine the influence of cubing on in situ ruminal
Effects of Cubing Alfalfa Hay on Development of Yearling Beef Heifers and In Situ Rate and Extent of Disappearance
disappearance. Traits measured in the heifer development trial were growth rate, forage intake, percentage bred by AI at the beginning of the breeding season, and pregnancy rate. An in situ trial was conducted to determine rate and extent of DM, CP, and NDF rumina I disappearance for alfalfa hay and cubes.
Materials and Methods Alfalfa hay was harvested from a single center pivot irrigated field in Southwestern Montana near the town of Dillon. The alfalfa, second cutting in mid-bloom, was baled into 909-kg square bales. Bales to be cubed were randomly selected from the entire stock to be used during the trial. The cubing process involved chopping the hay to 2 cm, adding a trace of bentonite as a binder, and heating to 70°e. The resulting cubes were approximately 3.2 cm in diameter with length ranging from 8 to 10 cm. All hay and cubes were kept under covered storage until fed. Samples of each hay type were randomly collected for CP (I), NDF (16), and ADIN (4) analyses. Heifer Development Trial. On February 27, 1992, approximately 600 mixed-breed yearling heifers owned by High Mountain Ranches, Inc., were rectally palpated to determine reproductive tract score. Heifers with scores of 1 or 2 were classified as prepuberal (10). Based upon these scores, 192 prepuberal heifers were identified and delivered to the Montana State University Livestock Teaching and Research Center on February 28, 1992. Upon arrival, initial weights were determined. Heifers were randomly assigned within two weight blocks to 1 of 16 pens. Each pen held 12 heifers and was assigned to one of two treatments: 1) cubed alfalfa hay (CA), or 2) long stem alfalfa hay (LA). Over the entire period, long stem hay averaged 18.47% CP and 35.04% ADF and cubed hay averaged 18.41% CP and 35.18% ADF. All heifers were given ad libitum access to a commerical trace mineral salt block.
The heifers were weighed every 28 d until breeding began. A barleybased supplement was fed to each pen at a rate of 1 kg per head per d beginning on April 30; MGA was added to the supplement at a rate to provide .5 mg.h-1 ·d-1 for 14 d beginning May 6. On June 6, the heifers were injected with 25 mg prostaglandin Fza, and a prebreeding weight was taken. Breeding was by AI 12 h after observed estrus. On July 3, a final weight was taken and the heifers were returned to the ranch near Dillon and exposed to clean-up bulls. The heifers were palpated for detection of pregnancy at the ranch on November 11. Pen was the experimental unit for analyses of weight gain, feed consumption, and feed conversion. Repeated measure procedures were used to analyze data for average daily feed consumption, gain, and feed conversion (15). Whole-plot effects included diet, weight block, and diet x weight block interaction. Subplot effects included period and all interactions of period with wholeplot effects. Because diet x weight block and period x diet x weight block interactions were not significant, these terms were deleted from the model and reduced models were fit to the data. Total weight gain, feed consumption, and feed conversion were analyzed by least squares procedures (15). The statistical model for these traits included diet, weight block, and diet x weight block interaction. Because the diet x weight block interaction was not Significant, this term was deleted and reduced models were fit to the data. Data for percentage bred by AI and overall conception rate were analyzed by chi-square procedures (15). In Situ Trial. Six mature crossbred beef cows fitted with ruminal cannulas were utilized in a switchback design. Animals were penned according to treatment and provided ad libitum access to either LA or CA. The CP, NDF, and ADIN on a DM basis were 18.47, 39.78, and 1.21 %, respectively, for CA and 16.32, 46.54, and 1.08%, respectively
31
for LA. Periods consisted of 14 d adaptation followed by 5 collection
d. Cubed alfalfa and LA were air dried and ground through a 2-mm screen in a Wiley mill. Five-gram samples were weighed into nylon bags. The bags were placed in a large drawstring mesh bag and suspended in the rumen at 0800 h on d 1 of the collection period. The hay type incubated in each animal was the same as the hay type being consumed by the animal. Duplicate bags were removed at 12, 24, 36, 48, 72, and 96 h and rinsed with cold water until the rinse water was clear. Bags were dried in a 60°C forced air oven for 48 h and weighed to determine DM content. Residues in the bags were analyzed for CP and NDF. All DM, CP, and NDF disappearance values were fitted to an iterative nonlinear regression equation as described by Robinson et al. (14) to estimate ruminal disappearance rate constants. Data were analyzed by least squares procedures (15). The statistical model for these traits included treatment, cow, and period.
Results and Discussion Heifer Development Trial. Intial weights of the heifers averaged 295 kg. Health and condition of the cattle during the trial were excellent. There were no cattle that required special treatment or hospital care. Least squares means for average daily feed consumption, average daily gain, and feed conversion by period are presented in Table 1. Periods are simply the intervals between weigh days. During each period, differences between diets were generally significant (P<.05) for average daily feed consumption, average daily gain, and feed conversion. For each trait, the interaction of diet x period was also significant. In each case, differences between diets in period 3 were smaller and(or) in an opposite direction than in other periods. The exact reason for these interactions is not known. The apparent "compensation" of the
32
Ansotegui et al.
TABLE 1. Least squares meansa for average daily feed consumption, average daily gain, and feed conversion by period b. lonn alfalfa
Cubed alfalfa
- -- -~
Item
SEM
PValue
Avg. daily feed consumption (kg/d) 9.8
11.8
.39
.003
2
12.0
13.8
.59
.05
3
12.5
15.1
.25
.0001
4
l3.0
12.5
.37
.32
Totai
ii.6
13.4
.28
.0004
Avg. daily gain (kg/d) 1.75
1.23
.05
.0001
2
1.05
.54
.10
.004
3
.99
1.29
.09
.04
4
1.96
1.08
.25
.03
Total
1.35
1.03
.03
.0001
.37
.0001
Feed conversion (kg:kg) 5.7
9.7
2
l3.3
30.1
3.7
.007
3
14.1
11 .8
1.3
.23
4
7.7
14.3
2.2
.06
Total
8.6
l3.2
aNumber of heifers
.39
.0001
=96 per diet.
bVv'eight peiiods: 1 = February 28 to tviarch 28 (28 d); 2 = March 28 to Aprii 25 (28 d); 3 = April 25 to May 23 (28 d); 4 = May 23 to June 4 (28 d). CDiet x period interaction significant (P=.0004). dDiet x period interaction significant (P=.005). eDiet x period interaction significant (P=.03).
TABLE 2. Reproductive performance of heifers.
Item
Cubed alfalfa
Long alfalfa
No. synchronized
96
96
No. bred AI
69
62
.28
No. pregnant (Nov. 1 1, 1992)
82
87
.27
PValue
.. -
differences from period 3 to period 4 leads us to speculate that animals on the two diets differed in fill between these two periods. Heifers fed CA consumed less forage (P<.OS) than heifers fed LA during the first three periods. However, during the last period (only 12 d) forage intakes were similar between diets. Over the entire study, heifers fed cuoes consumed 13.S% less forage than heifers fed LA (P<.OOI). Feed wastage could not be measured; however, our observations of the pens suggest that heifers fed LA wasted considerably more forage than heifers fed cubed hay. Though not specifically measured in this study, it would appear that cubing hay reduces the animal's ability to sort leaves from stems. Cubing improved average daily gain and feed conversion during three of the four periods (P<.OS). The exception was period 3, in which the diets switched ranks (P<.OS). During the third period, heifers were removed from MGA and began to exhibit estrous activity. This may be related to this change in performance during period 3. Overall, heifers fed CA gained 31 % faster and had 34% better feed conversion than heifers fed LA. Reproductive performance is summarized in Table 2. The number of heifers that exhibited estrus during the synchronization period and the number of heifers pregnant were not different between diets (b.20). Although heifers fed CA gained more weight than heifers fed LA, all heifers reached recommended weight for puberty at the beginning of the breeding season (average, 409 kg) . The number bred during the AI period was less than expected for yearling heifers of this age and weight. However, due to the design of the experiment, only the most immature heifers from the original 600 heifers were used in the study. In Situ Trial. Extent of DM disappearance (Table 3) at 12, 24, 36, 48, 72, and 96 h for CA was higher (P<.OI) than LA. Extent of NDF and CP disappearance at 24, 36, 48, 72,
33
Effects of Cubing Alfalfa Hay on Development of Yearling Beef Heifers and In Situ Rate and Extent of Disappearance
and 96 h were higher (P <.01) for CA than for LA; however, values were similar (P> .09) at 12 h for both CP and NDF disappearance. In an artificial rumen study, Radloff et al. (12) found that a greater amount of alfalfa DM substrate disappeared with inoculum from steers fed cubed hay compared to inoculum from steers fed baled alfalfa. The DM and NDF disappearance rate constants for CA (.27 and .11, respectively) were higher (P<.04) than LA (.16 and .08, respectively) . Crude protein rate constants were similar (P> .05) for CA (.33) and LA (.28) . Kercher et al. (5) found no differences in protein digestibility or nitrogen balance due to methods of making alfalfa cubes. The results of this study are in general agreement with earlier research on the merits of cubed vs baled hay. Miller et al. (11) reported that steers fed a diet in which part of the hay was pelleted grew faster than steers that received all hay in long form. Kercher et al. (6, 7) conducted two studies comparing baled, cubed, and ensiled alfalfa for beef calves. In the earlier study they found that steer calves fed haylage or cubes consumed less dry matter than steers fed baled hay and were more efficient in converting forage to beef. In the second study they found that beef calves fed cubes consumed more dry matter, grew faster, and were more efficient than calves fed baled hay. Results of the in situ trial indicate that cubing alfalfa hay increases DM and NDF disappearance rate. Changes in ruminal environment were influenced by the cubing process (e.g., heating) and not by particle size because all in situ samples were ground through a 2mm screen prior to rumen submersion. These differences in rumina I kinetics may prove to be an advantage to cubing hay, resulting in lower forage intake or increased performance from similar intakes.
TABLE 3. Ruminal disappearance of OM at 12, 24, 36, 48, 72, and 96 h. Item
12 h
24 h
36 h
48h
72 h
96 h
DM dissappearance (%) Long alfalfa
67.0 a
73.9 a
74.0a
75.5 a
72.5 a
68.1a
Cubed alfalfa
74.2b
80.6 b
81.7 b
83.0 b
82.2b
79.6 b
1.1
.5
.4
1.2
1.7
SE
.6
CP disappearance (%) Long alfalfa
89.1
92.5 a
91.P
93.5 a
90.6 a
87.7 a
Cubed alfalfa
91.5
94.4 b
94.7 b
95.6 b
94.6 b
93.1b
.3
.6
.3
.5
SE
.9
.8
NDF disappearance (%) Long alfalfa
35.7
48.0 a
49.6 a
52.7a
51.9 a
49.3 a
Cubed alfalfa
40.5
54.2 b
57.1 b
60.1 b
61.0b
56.5 b
1.1
.7
1.4
1.8
SE
1.9
.9
a,bMeans within a column with no common superscript differ (P<.Ol).
Implications When alfalfa cubes are fed under conditions similar to this study, cubing alfalfa hay will reduce feed use and improve growth rate. Presumably, this is due to reduced feed wastage and increased digestion. Results of the in situ trial indicate that cubing alfalfa hay increases DM and NDF disappearance rate. These differences on ruminal kinetics may prove to be an advantage to cubing hay, resulting in improved growth rate and feed conversion in yearling heifers. Labor and equipment requirements were not measured in this study. However, assuming feeding and handling costs to be similar, our results suggest that cubed alfalfa hay should be worth up to 30% more/kg than long hay from the same harvest.
Literature Cited 1. AOAC. 1980. Official Methods of Analysis. (13th Ed.). Association of Official Analytical Chemists. Washington, DC. 2. Anderson, M. J., G. E. Stoddard, C. H. Mickelsen, and R. C. Lamb. 1975. Cubed versus baled alfalfa for dairy cows. J. Dairy Sci. 58:72. 3. Butcher, J. E., N. J. Stenquist, and W. A. Suarez. 1973. Cubed versus chopped alfalfa for growing beef cattle. J. Anim. Sci. 37:338. (Abs.) . 4. Goering, H. K., and P. J. Van Soest. 1970. Forage fiber analysis. USDA Handbook No. 379 P 11. Washington, DC. 5. Kercher, C. J., S. Benamer, W. Smith, and L. Paules. 1978. Value of alfalfa cubes in replacing barley for yearling steers. Proc. West. Sect. Am. Soc. Anim. Sci. 29:410.
34
6. Kercher, C. J., W. Smith, and 1. Paules. 1970. Baled, cubed and ensiled alfalfa for beef calves. Proc. West. Sect. Amer. Soc. Anim. Sci. 21 :285. 7. Kercher, C. ]., W. Smith, and 1. Paules. 1971. Baled, cubed and ensiled alfalfa for beef calves. Proc. West. Sect. Amer. Soc. Anim. Sci. 22:33. 8. Kercher, c.]., W. Smith, and 1. Paules. 1972. Alfalfa - baled, cubed or haylage? Wyo. Agric. Exp Sta. Res. J. 62. 9. Klusmeyer, T. H., M. R. Cameron, G. C. McCoy, and J. H. Clark. 1990. Effects of feed processing and frequency of feeding on ruminal fermentation, milk production and milk composition. ]. Dairy Sci. 73:3538.
Ansotegui et al.
10. LeFever, D. G., and K. G. Odde. 1986. Predicting reproductive performance in beef heifers by reproductive tract evaluation before breeding. CSU Beef Prog. Report. p 13. Fort Collins, CO. 11. Miller, ]. 1., ]. ]. Drain, R. 1. Park, and M. V. Wallentine. 1960. The value of hay pellets when fed with grass silage and mixed hay in wintering rations for steer calves. ]. Anim. Sci. 19:715.
alfalfa on rumen function. Proc. West. Sect. Amer. Soc. Anim. Sci. 27:155. 14. Robinson, R. H., J. G. Fadal, and S. Tamminga. 1986. Evaluation of mathematical m()npls.
to
nplli;.rrihp
nplltr~l nptpTO'pnt rp~;ill'P
;~-t~;~;~f-it~-~~~~~ptibii;tit~-d~g;~d~ti;~in the rumen. Anim. Feed Sci. Techno!. 15:249. 15. SAS. 1988. Statistical analysis system. SAS Inst. Inc. Raleigh, NC.
12. Radloff, H. D., B. Marshall, S. 1. Maxfield, 16. Van Soest, P.J., andJ. B. Robertson. 1980. H. 1. Henschel, and R. W. Rice. 1975. Effect of Systems on analysis of evaluating fibrous cubing or baling alfalfa on rumen function. - feeds. In: W. J.-~igden, C. C. BalGh, and M. Proc. West. Sect. Am. Sac. Anim. Sci. 26:140. Graham (Ed.). Standardization of Analytical Methodology for Feeds. p 49. Int. Res. Dev. 13. Riley, R. E. Jr., H. D. Radloff, and S. Ctr. Pub. No. 134e. Ottawa, ON, Canada. Maxfield. 1976. Effect of cubing or baling
Effects of Cubing Alfalfa Hay on Development of Yearling Beef Heifers and In Situ Rate and Extent ofnic~nno~r~nrol,2 ...., hl",.4t-'t-'~UI UI I~~ R. P. ANSOTEGUI, E.
J. SWENSSON, M. W. TESS, K. S. BRYAN, C. K. CLARK,
and R. M. BROWNSON, PAS Montana State University, Bozeman, MT 59717
Abstract The objective of this study was to evaluate the effects of cubing alfalfa on heifer development and in situ rumina I NDF and CP disappearance. One hundred ninety-two prepuberal crossbred heifers were allotted to 16 pens with each pen randomly allotted to treatment; 1) cubed alfalfa (CA) or 2) long alfalfa (LA). Diets were consumed ad libitum. Heifers were weighed every 28 d throughout the 96-d trial. Following synchronization, heifers were bred by AI 12 h after observed estrus. Hay intake by CA heifers was lower (p<.05) than LA heifers (11.6vs 13.5 kgper head per d), butADG was faster (P<. 05) for CA heifers than those fed LA (1.35 vs 1.03 kgper head per d). Feed per kilogram ofgain was lower (p<.05) for heifers fed CA than for heifers fed LA (8.6 vs 13.2 kg:kg). No differences were observed in number ofheifers bred AI (P>.25) or in total pregnancy (p>.25). Six mature beefcows fitted with ruminal cannula were used in a switchback design to determine influence ofcubing on in situ ruminal CP and NDF disappearance.
During each period animals consumed their respective diets ad libitum for 14 d of adaptation and 5 d ofdata collection. Nylon bags containing 5-g samples of either CA or LA were ruminally incubated for 12,24,36,48,72, and 96 h. Bag residues were analyzed for DM, Cp, and NDF content. The DM and NDF disappearance rate constants and extent ofDM disappearance for CA (.27, .11, and 79.6%, respectively) were higher (p<.04) than LA (.16, .08, and 68.1%, respectively). Crude protein rate constants were similar (p>.05) forCA (.33) and LA (.28). Results from the heifer development trial suggest that heifers fed CA gained faster and were more efficient than heifers fed LA. No differences were detected in reproductive performance, possibly because all heifers reached the recommended weight for puberty at the beginning of the breeding season regardless of treatment (average, 409 kg). Results from the in situ trial indicate ruminal DM and NDF disappearance were enhanced by cubing alfalfa, but not rate of CP disappearance. (Key Words: Beef Heifers, Puberty, Alfalfa Cubes.)
1 Mont. Agric. Exp. Sta. J. Series Number J-3008. 2The authors gratefully acknowledge High The effects of changing the physiMountain Ranches, Dell, MT for supporting this research. cal form of long-stem hay on growth
Introduction
Reviewed by N. A. Cole and T. W. White.
and feed intake have been studied in
growing-finishing cattle. Compared with long hay, cubing alfalfa has been shown to be advantageous due to increased ease of transport, storage, and feeding, plus reduced feed waste (2,9). Cubing has been shown to improve daily gain (11) and feed intake and conversion (6, 7). Butcher et al. (3) found that cattle consume more cubed hay than baled hay, resulting in increased weight gain. Cubing alfalfa hay has been reported to increase DM and CP digestibility while reducing retention time in the rumen when compared with baled alfalfa (13). However, other researchers have reported that chopped or baled alfalfa hay is more digestible than cubed hay (8, 12). Few studies have been conducted to evaluate the effects of cubing hay on reproductive performance in replacement heifers. Because the greatest advantages to feeding cubed hay have been seen in growing cattle fed high roughage diets, it was hypothesized that cubing high quality hay might also improve reproductive development of replacement heifers. The objectives of this study were to evaluate effects of cubing alfalfa hay on development and reproductive performance of yearling beef heifers and to determine the influence of cubing on in situ ruminal
Effects of Cubing Alfalfa Hay on Development of Yearling Beef Heifers and In Situ Rate and Extent of Disappearance
disappearance. Traits measured in the heifer development trial were growth rate, forage intake, percentage bred by AI at the beginning of the breeding season, and pregnancy rate. An in situ trial was conducted to determine rate and extent of DM, CP, and NDF rumina I disappearance for alfalfa hay and cubes.
Materials and Methods Alfalfa hay was harvested from a single center pivot irrigated field in Southwestern Montana near the town of Dillon. The alfalfa, second cutting in mid-bloom, was baled into 909-kg square bales. Bales to be cubed were randomly selected from the entire stock to be used during the trial. The cubing process involved chopping the hay to 2 cm, adding a trace of bentonite as a binder, and heating to 70°e. The resulting cubes were approximately 3.2 cm in diameter with length ranging from 8 to 10 cm. All hay and cubes were kept under covered storage until fed. Samples of each hay type were randomly collected for CP (I), NDF (16), and ADIN (4) analyses. Heifer Development Trial. On February 27, 1992, approximately 600 mixed-breed yearling heifers owned by High Mountain Ranches, Inc., were rectally palpated to determine reproductive tract score. Heifers with scores of 1 or 2 were classified as prepuberal (10). Based upon these scores, 192 prepuberal heifers were identified and delivered to the Montana State University Livestock Teaching and Research Center on February 28, 1992. Upon arrival, initial weights were determined. Heifers were randomly assigned within two weight blocks to 1 of 16 pens. Each pen held 12 heifers and was assigned to one of two treatments: 1) cubed alfalfa hay (CA), or 2) long stem alfalfa hay (LA). Over the entire period, long stem hay averaged 18.47% CP and 35.04% ADF and cubed hay averaged 18.41% CP and 35.18% ADF. All heifers were given ad libitum access to a commerical trace mineral salt block.
The heifers were weighed every 28 d until breeding began. A barleybased supplement was fed to each pen at a rate of 1 kg per head per d beginning on April 30; MGA was added to the supplement at a rate to provide .5 mg.h-1 ·d-1 for 14 d beginning May 6. On June 6, the heifers were injected with 25 mg prostaglandin Fza, and a prebreeding weight was taken. Breeding was by AI 12 h after observed estrus. On July 3, a final weight was taken and the heifers were returned to the ranch near Dillon and exposed to clean-up bulls. The heifers were palpated for detection of pregnancy at the ranch on November 11. Pen was the experimental unit for analyses of weight gain, feed consumption, and feed conversion. Repeated measure procedures were used to analyze data for average daily feed consumption, gain, and feed conversion (15). Whole-plot effects included diet, weight block, and diet x weight block interaction. Subplot effects included period and all interactions of period with wholeplot effects. Because diet x weight block and period x diet x weight block interactions were not significant, these terms were deleted from the model and reduced models were fit to the data. Total weight gain, feed consumption, and feed conversion were analyzed by least squares procedures (15). The statistical model for these traits included diet, weight block, and diet x weight block interaction. Because the diet x weight block interaction was not Significant, this term was deleted and reduced models were fit to the data. Data for percentage bred by AI and overall conception rate were analyzed by chi-square procedures (15). In Situ Trial. Six mature crossbred beef cows fitted with ruminal cannulas were utilized in a switchback design. Animals were penned according to treatment and provided ad libitum access to either LA or CA. The CP, NDF, and ADIN on a DM basis were 18.47, 39.78, and 1.21 %, respectively, for CA and 16.32, 46.54, and 1.08%, respectively
31
for LA. Periods consisted of 14 d adaptation followed by 5 collection
d. Cubed alfalfa and LA were air dried and ground through a 2-mm screen in a Wiley mill. Five-gram samples were weighed into nylon bags. The bags were placed in a large drawstring mesh bag and suspended in the rumen at 0800 h on d 1 of the collection period. The hay type incubated in each animal was the same as the hay type being consumed by the animal. Duplicate bags were removed at 12, 24, 36, 48, 72, and 96 h and rinsed with cold water until the rinse water was clear. Bags were dried in a 60°C forced air oven for 48 h and weighed to determine DM content. Residues in the bags were analyzed for CP and NDF. All DM, CP, and NDF disappearance values were fitted to an iterative nonlinear regression equation as described by Robinson et al. (14) to estimate ruminal disappearance rate constants. Data were analyzed by least squares procedures (15). The statistical model for these traits included treatment, cow, and period.
Results and Discussion Heifer Development Trial. Intial weights of the heifers averaged 295 kg. Health and condition of the cattle during the trial were excellent. There were no cattle that required special treatment or hospital care. Least squares means for average daily feed consumption, average daily gain, and feed conversion by period are presented in Table 1. Periods are simply the intervals between weigh days. During each period, differences between diets were generally significant (P<.05) for average daily feed consumption, average daily gain, and feed conversion. For each trait, the interaction of diet x period was also significant. In each case, differences between diets in period 3 were smaller and(or) in an opposite direction than in other periods. The exact reason for these interactions is not known. The apparent "compensation" of the
32
Ansotegui et al.
TABLE 1. Least squares meansa for average daily feed consumption, average daily gain, and feed conversion by period b. lonn alfalfa
Cubed alfalfa
- -- -~
Item
SEM
PValue
Avg. daily feed consumption (kg/d) 9.8
11.8
.39
.003
2
12.0
13.8
.59
.05
3
12.5
15.1
.25
.0001
4
l3.0
12.5
.37
.32
Totai
ii.6
13.4
.28
.0004
Avg. daily gain (kg/d) 1.75
1.23
.05
.0001
2
1.05
.54
.10
.004
3
.99
1.29
.09
.04
4
1.96
1.08
.25
.03
Total
1.35
1.03
.03
.0001
.37
.0001
Feed conversion (kg:kg) 5.7
9.7
2
l3.3
30.1
3.7
.007
3
14.1
11 .8
1.3
.23
4
7.7
14.3
2.2
.06
Total
8.6
l3.2
aNumber of heifers
.39
.0001
=96 per diet.
bVv'eight peiiods: 1 = February 28 to tviarch 28 (28 d); 2 = March 28 to Aprii 25 (28 d); 3 = April 25 to May 23 (28 d); 4 = May 23 to June 4 (28 d). CDiet x period interaction significant (P=.0004). dDiet x period interaction significant (P=.005). eDiet x period interaction significant (P=.03).
TABLE 2. Reproductive performance of heifers.
Item
Cubed alfalfa
Long alfalfa
No. synchronized
96
96
No. bred AI
69
62
.28
No. pregnant (Nov. 1 1, 1992)
82
87
.27
PValue
.. -
differences from period 3 to period 4 leads us to speculate that animals on the two diets differed in fill between these two periods. Heifers fed CA consumed less forage (P<.OS) than heifers fed LA during the first three periods. However, during the last period (only 12 d) forage intakes were similar between diets. Over the entire study, heifers fed cuoes consumed 13.S% less forage than heifers fed LA (P<.OOI). Feed wastage could not be measured; however, our observations of the pens suggest that heifers fed LA wasted considerably more forage than heifers fed cubed hay. Though not specifically measured in this study, it would appear that cubing hay reduces the animal's ability to sort leaves from stems. Cubing improved average daily gain and feed conversion during three of the four periods (P<.OS). The exception was period 3, in which the diets switched ranks (P<.OS). During the third period, heifers were removed from MGA and began to exhibit estrous activity. This may be related to this change in performance during period 3. Overall, heifers fed CA gained 31 % faster and had 34% better feed conversion than heifers fed LA. Reproductive performance is summarized in Table 2. The number of heifers that exhibited estrus during the synchronization period and the number of heifers pregnant were not different between diets (b.20). Although heifers fed CA gained more weight than heifers fed LA, all heifers reached recommended weight for puberty at the beginning of the breeding season (average, 409 kg) . The number bred during the AI period was less than expected for yearling heifers of this age and weight. However, due to the design of the experiment, only the most immature heifers from the original 600 heifers were used in the study. In Situ Trial. Extent of DM disappearance (Table 3) at 12, 24, 36, 48, 72, and 96 h for CA was higher (P<.OI) than LA. Extent of NDF and CP disappearance at 24, 36, 48, 72,
33
Effects of Cubing Alfalfa Hay on Development of Yearling Beef Heifers and In Situ Rate and Extent of Disappearance
and 96 h were higher (P <.01) for CA than for LA; however, values were similar (P> .09) at 12 h for both CP and NDF disappearance. In an artificial rumen study, Radloff et al. (12) found that a greater amount of alfalfa DM substrate disappeared with inoculum from steers fed cubed hay compared to inoculum from steers fed baled alfalfa. The DM and NDF disappearance rate constants for CA (.27 and .11, respectively) were higher (P<.04) than LA (.16 and .08, respectively) . Crude protein rate constants were similar (P> .05) for CA (.33) and LA (.28) . Kercher et al. (5) found no differences in protein digestibility or nitrogen balance due to methods of making alfalfa cubes. The results of this study are in general agreement with earlier research on the merits of cubed vs baled hay. Miller et al. (11) reported that steers fed a diet in which part of the hay was pelleted grew faster than steers that received all hay in long form. Kercher et al. (6, 7) conducted two studies comparing baled, cubed, and ensiled alfalfa for beef calves. In the earlier study they found that steer calves fed haylage or cubes consumed less dry matter than steers fed baled hay and were more efficient in converting forage to beef. In the second study they found that beef calves fed cubes consumed more dry matter, grew faster, and were more efficient than calves fed baled hay. Results of the in situ trial indicate that cubing alfalfa hay increases DM and NDF disappearance rate. Changes in ruminal environment were influenced by the cubing process (e.g., heating) and not by particle size because all in situ samples were ground through a 2mm screen prior to rumen submersion. These differences in rumina I kinetics may prove to be an advantage to cubing hay, resulting in lower forage intake or increased performance from similar intakes.
TABLE 3. Ruminal disappearance of OM at 12, 24, 36, 48, 72, and 96 h. Item
12 h
24 h
36 h
48h
72 h
96 h
DM dissappearance (%) Long alfalfa
67.0 a
73.9 a
74.0a
75.5 a
72.5 a
68.1a
Cubed alfalfa
74.2b
80.6 b
81.7 b
83.0 b
82.2b
79.6 b
1.1
.5
.4
1.2
1.7
SE
.6
CP disappearance (%) Long alfalfa
89.1
92.5 a
91.P
93.5 a
90.6 a
87.7 a
Cubed alfalfa
91.5
94.4 b
94.7 b
95.6 b
94.6 b
93.1b
.3
.6
.3
.5
SE
.9
.8
NDF disappearance (%) Long alfalfa
35.7
48.0 a
49.6 a
52.7a
51.9 a
49.3 a
Cubed alfalfa
40.5
54.2 b
57.1 b
60.1 b
61.0b
56.5 b
1.1
.7
1.4
1.8
SE
1.9
.9
a,bMeans within a column with no common superscript differ (P<.Ol).
Implications When alfalfa cubes are fed under conditions similar to this study, cubing alfalfa hay will reduce feed use and improve growth rate. Presumably, this is due to reduced feed wastage and increased digestion. Results of the in situ trial indicate that cubing alfalfa hay increases DM and NDF disappearance rate. These differences on ruminal kinetics may prove to be an advantage to cubing hay, resulting in improved growth rate and feed conversion in yearling heifers. Labor and equipment requirements were not measured in this study. However, assuming feeding and handling costs to be similar, our results suggest that cubed alfalfa hay should be worth up to 30% more/kg than long hay from the same harvest.
Literature Cited 1. AOAC. 1980. Official Methods of Analysis. (13th Ed.). Association of Official Analytical Chemists. Washington, DC. 2. Anderson, M. J., G. E. Stoddard, C. H. Mickelsen, and R. C. Lamb. 1975. Cubed versus baled alfalfa for dairy cows. J. Dairy Sci. 58:72. 3. Butcher, J. E., N. J. Stenquist, and W. A. Suarez. 1973. Cubed versus chopped alfalfa for growing beef cattle. J. Anim. Sci. 37:338. (Abs.) . 4. Goering, H. K., and P. J. Van Soest. 1970. Forage fiber analysis. USDA Handbook No. 379 P 11. Washington, DC. 5. Kercher, C. J., S. Benamer, W. Smith, and L. Paules. 1978. Value of alfalfa cubes in replacing barley for yearling steers. Proc. West. Sect. Am. Soc. Anim. Sci. 29:410.
34
6. Kercher, C. J., W. Smith, and 1. Paules. 1970. Baled, cubed and ensiled alfalfa for beef calves. Proc. West. Sect. Amer. Soc. Anim. Sci. 21 :285. 7. Kercher, C. ]., W. Smith, and 1. Paules. 1971. Baled, cubed and ensiled alfalfa for beef calves. Proc. West. Sect. Amer. Soc. Anim. Sci. 22:33. 8. Kercher, c.]., W. Smith, and 1. Paules. 1972. Alfalfa - baled, cubed or haylage? Wyo. Agric. Exp Sta. Res. J. 62. 9. Klusmeyer, T. H., M. R. Cameron, G. C. McCoy, and J. H. Clark. 1990. Effects of feed processing and frequency of feeding on ruminal fermentation, milk production and milk composition. ]. Dairy Sci. 73:3538.
Ansotegui et al.
10. LeFever, D. G., and K. G. Odde. 1986. Predicting reproductive performance in beef heifers by reproductive tract evaluation before breeding. CSU Beef Prog. Report. p 13. Fort Collins, CO. 11. Miller, ]. 1., ]. ]. Drain, R. 1. Park, and M. V. Wallentine. 1960. The value of hay pellets when fed with grass silage and mixed hay in wintering rations for steer calves. ]. Anim. Sci. 19:715.
alfalfa on rumen function. Proc. West. Sect. Amer. Soc. Anim. Sci. 27:155. 14. Robinson, R. H., J. G. Fadal, and S. Tamminga. 1986. Evaluation of mathematical m()npls.
to
nplli;.rrihp
nplltr~l nptpTO'pnt rp~;ill'P
;~-t~;~;~f-it~-~~~~~ptibii;tit~-d~g;~d~ti;~in the rumen. Anim. Feed Sci. Techno!. 15:249. 15. SAS. 1988. Statistical analysis system. SAS Inst. Inc. Raleigh, NC.
12. Radloff, H. D., B. Marshall, S. 1. Maxfield, 16. Van Soest, P.J., andJ. B. Robertson. 1980. H. 1. Henschel, and R. W. Rice. 1975. Effect of Systems on analysis of evaluating fibrous cubing or baling alfalfa on rumen function. - feeds. In: W. J.-~igden, C. C. BalGh, and M. Proc. West. Sect. Am. Sac. Anim. Sci. 26:140. Graham (Ed.). Standardization of Analytical Methodology for Feeds. p 49. Int. Res. Dev. 13. Riley, R. E. Jr., H. D. Radloff, and S. Ctr. Pub. No. 134e. Ottawa, ON, Canada. Maxfield. 1976. Effect of cubing or baling