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| Author(s): |
Pablo de Souza Castagnino
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Jaboticabal. 2018-03-01. |
| Institution: | Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal |
| Defense date: | 2018-02-05 |
| Advisor: | Telma Teresinha Berchielli; Giovani Fiorentini |
| Abstract | |
Glycerol is a substrate used for bacteria that metabolize ruminal lactate and virginiamicyn is a non-ionophore antibiotic that inhibits the growth of gram-positive lactate-producing bacteria. Two experiments were conducted to evaluate the effects of crude glycerin (CG) combined with virginiamycin (VM) on intake, digestibility, ruminal fermentation, microbial population, performance, carcass traits and fatty acid profile of meat from feedlot Nellore cattle. Treatments were arranged in 2 × 2 factorial design: diets without virginiamycin (VM-) or virginiamycin at 25 mg/kg DM (VM+) combined with diets without crude glycerin (CG-) or CG (80% glycerol) at 100 g/kg DM (CG+). The sugar cane bagasse was used as the exclusive roughage in the proportion of 20% in the dry matter (DM) of diet and crude glycerin replaced corn in the diet formulation. In the first experiment, eight rumen fistulated bulls (BW= 600 ± 34 kg; 26 ± 3 months) were used in a replicated 4 × 4 Latin square (21-d periods) to evaluate the digestibility, ruminal fermentation and microbial population. The intake of DM had a tendency to be greater in CG+ than CG- diets (P = 0.07). Apparent total tract digestibilities of nutrients were similar among diets (P ≥ 0.10). Diets with CG or VM had similar values of pH (mean=6.15; P ≥ 0.10). The proportion of propionate increased 27.5% in CG+ diets, regardless of VM inclusion (P = 0.01). In the second experiment, forty-eight bulls with initial BW (408.4 ± 22.2 kg; 21 ± 2 months) were used in a randomized complete block design for carcass traits and animal performance evaluation. The intake of DM, cold carcass weight and cold carcass dressing was greater in crude glycerin diets (P < 0.05). VM had a slightly tendency to increase ADG and feed efficiency (P < 0.1). Total unsaturated fatty acids (UFA) concentration in the longissimus muscle increased 6.08% in diets CG+ diets (P < 0.05), however n-6/n-3 ratio remained constant among all treatments (P > 0.10). Glycerin had a positive effects on fermentation products and could replace virginiamycin with increment of Megasphaera elsdenii abundance and UFA deposition on meat. However, simultaneous administration of VM and CG does not interfere positively on rumen fermentation products, performance and carcass traits of feedlot Nellore cattle. (AU) | |
| FAPESP's process: | 15/03918-4 - CRUDE GLYCERIN ASSOCIATED WITH VIRGINIAMICYN IN HIGH-CONCENTRATE DIETS ON PERFORMANCE AND RUMINAL FERMENTATION PARAMETERS OF NELLORE STEERS |
| Grantee: | Pablo de Souza Castagnino |
| Support Opportunities: | Scholarships in Brazil - Doctorate |