Suplementación proteica en vacas Brahman de primer parto
To evaluate the effect of protein supplementation on productive and reproductive performance and rumen fermentation processing in female cattle two experiments were carried out. In the first, 117 pregnant Brahman heifers with average body weight of 393.5 ± 3.05 kg of 3 (n=84) and 4 (n=33) years old,...
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2013
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| Online Access: | http://hdl.handle.net/10872/3706 |
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| Summary: | To evaluate the effect of protein supplementation on productive and reproductive performance and rumen fermentation processing in female cattle two experiments were carried out. In the first, 117 pregnant Brahman heifers with average body weight of 393.5 ± 3.05 kg of 3 (n=84) and 4 (n=33) years old, were divided into three uniform groups by body weight and possible date of calving, and were assigned to three supplement (1 kg·animal·d-1) containing mainly corn meal (CM), hydrolyzed feather meal (HFM) and soybean meal (SBM). The supplements had 20.69, 42.75 and 42.54% CP, and 2.84, 2.71 and 2.77 Mcal of ME·kg-1 DM, respectively for CM, HFM and SBM. The animals grazed on pastures of U. humidicola and the stocking rate was 0.44 AU·ha-1. Supplementation started approximately 45 d before calving and was maintained up to the end of the breeding season (BS), that was under natural mating. Cows’s body weight changes, wither height, body score condition (BSC) and calf birth weight were recorded, and assessment of glucose, β-hydroxybutyrate, nonesterified fatty acids and urea were made. Pregnancy was determined by transrectal palpation at 54 d once completed the BS. Data of body weight change of the cows, calf birth weight, wither height and BSC were analyzed by ANOVA under a completely randomized design with 2 x 3 unbalanced factorial arrangements. The pregnancy was analyzed by exact logistic regression. In the second experiment, in cows provided with rumen fistulae, were tested the same supplements of experiment I, including an additional treatment (negative control), fed with forage only (F) and ruminal and blood variables were also evaluated. In Experiment I, the forage had 2.63 ± 0.1% CP and 77.56 ± 0.4% NDF. From calving to beginning of BS, SBM gained (g·d-1) more weight (258, P<0.05) than HFM (41), while CM lost weight (-56). The BSC at the beginning of the BS was higher (P<0.05) in SBM (2.75 kg·cm-1) respect to HFM (2.62 kg·cm-1) and CM (2.63 kg·cm-1), and superiority remained until the end of the BS. No differences were observed in the presence of ovarian structures and blood chemistry by supplements and age effects (P>0.05). The conception rate (P>0.05) at 54 d of completing the BS was 53.6, 63.6 and 61.2% for CM, HFM and SBM, respectively. In experiment II, the pH of rumen liquor at 3 h (P<0.05) and 6 h (P<0.09) after supplementation were lower in HPH respect to F (6.56 vs. 7.09 and 6.48 vs. 706, respectively). Ammonia nitrogen was higher (P<0.05) in SBM, and acetic and propionic acids at 0 h were higher (P<0.05) in SBM (52.50 and 28.38 µmol·mL-1, respectively) and HFM (46.66 and 24.32 µmol·mL-1, respectively) and the superiority was maintained until 6 h. Organic matter degradation of forage (%) at 72 h was higher (P<0.05) in HFM (44) and SBM (42). Organic matter degradation of the supplements did not differ (P>0.05), with values at 72 h of 74.6, 81.8 and 82.9 % for HFM, CM and SBM, respectively, while the CP degradation of supplements was lower (P<0.05) in HFM (64.18%). Serum glucose was not affected by the supplements, unlike urea, where SBM showed higher concentrations (P<0.05) at all sampling times. Supplementation with one kg of SBM, improved daily gain and showed less BSC loss in first calf heifers, increased ruminal ammonia nitrogen, and together with HFM, the organic matter degradation of forage was also improved. However, the magnitudes of the registered changes were not sufficient to improve the reproductive performance of first calf heifers. |
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