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| Author(s): |
Marcelo de Queiroz Manella
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2004-04-16 |
| Advisor: | Celso Boin |
| Abstract | |
Six rumen cannulated Nelore steer were used in replicated latin square design (3 x 3), with the objective of analyze the effects of different ratios of concentrate (20, 40, 60%). The feed evaluated were soybean hulls, com, sorghum grain, soybean meal, cottonseed meal and com gluten feed. There was an interaction among feed and incubation period for microbial contamination. The residue contamination increased with rumen exposure for ali feeds, and the main variations detected were with % residual bacterial nitrogen (%Nbact). The com, cottonseed meal and the sorghum showed higher %Nbact after 24 and 48h of rumen exposure, and the soy bean meal only after 48 h. The com gluten feed and soy bean hulls had the largest %Nbact contamination afier 24, 48 and 60h of rumen exposure. The treatment with 60% of concentrate, when compared with 20 and 40% had lower mean pH, higher volatile fatty acids production (P<0,05), lower acetic acid proportion, because the increased of the proportion of propionic acid (P<0,05), which caused a lower ratios of acetate:propionate, higher molar proportion of butyric acid, and lower rumen ammonia nitrogen (N-NH3) The soybean hulls had higher rumen effective degradability when corrected for microbial contamination for all estimated passages rates. The com had higher rumen dry matter effective degradability (ED) with animals on 60% concentrated treatment, and the CP were higher only with passage rates of 5%/h. The CP effective degradability of the com gluten feed showed a significant difference when corrected for microbial nitrogen contamination. The dry matter ED of soy bean meal of animal on 60% concentrate diet showed lower values with passage rates of 5 and 8%/h. The microbial contamination correction of the cottonseed meal residues had a significant effect of dry matter ED with all the passage rates, and for the CP were significant only with estimates of 2%/h. The in vitro intestinal digestibilities rumen undegradable protein (RUP) were higher to soy bean hulls (81,7%), com (87,1%) and sorghum (82,4%) than com gluten meal (57,6). The total digestibility estimated (rumen and intestine) were different and only com and com gluten meal had similar values. It was not detected variations on bacterial CP and amino acid composition among diets. There was a significant effect of feed for amino acids degradation, with the lower values for sorghum and the higher for com gluten feed. The individual amino acid degradability were variable with different rates of degradability, and that resulted on profile changes after rumen exposure. (AU) | |