Probiótico na terminação de bovinos em pastejo durante o período da seca
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2019-02-26
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Universidade Federal de Goiás
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Probiotics have been promised to be an alternative additive to antibiotic use and as a growth promoter. However, the performance results of animals fed probiotics are variable. The objectives were to evaluate the productive performance of Nellore bulls on grazing system for intensive fattening during the dry season, receiving probiotic concentrate composed of Bacillus toyonensis; influence of probiotic on ruminal and intestinal mucosa development and probiotic effect on digestibility and ruminal fermentation. The experiment was carried out between July and November 2017, which corresponds to the dry period in the region. Four animals were slaughtered at the beginning of the experiment so that the initial carcass yield could be estimated. Nellore bulls (n = 80) with initial mean weight of 354.02 ± 3.38 kg were blocked according to body weight and divided into two treatments: concentrate with probiotic and concentrate without probiotic (control). They were allocated in 16 paddocks formed by Urochloa brizantha, supplemented at 2% of the body weight in concentrate. At the end of 133 days of experiment, the animals were slaughtered and data of carcass weight, yield, carcass gain, average daily carcass gain and 12th-rib fat thickness were obtained. The in vivo digestibility assay was performed with eight rumen cannulated steers, in a cross over 2x2 design, with two treatments and two periods. Titanium dioxide was used as an external marker to estimate fecal excretion and iFDN was used as an internal marker to estimate dry matter intake. On the last day of each experimental period, ruminal fluid was collected to evaluate the concentration of short chain fatty acids and ammoniacal nitrogen. The use of probiotic composed of Bacillus toyonensis did not improve final body weight (528.2 ± 3.38 kg – p=0,2360) nor the daily average gain (1,333 kg– p= 0,2531) and feed efficiency (0.165– p=0,2016). The subcutaneous fat thickness was lower in animals receiving the probiotic (4.06 vs. 2.97 mm mm – p=0,0423). There was no influence of probiotic on other carcass traits. No significant effect on the development of the ruminal and intestinal epithelium was observed with the use of probiotic. Bacillus toyonensis did not improve dry matter intake and nutrient digestibility. There was no effect on rumen fermentation. Probiotic based on Bacillus toyonensis altered fat deposition in carcasses.
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CALAÇA, A. M. M. Probiótico na terminação de bovinos em pastejo durante o período da seca. 2019. 42 f. Dissertação (Mestrado em Zootecnia) - Universidade Federal de Goiás, Goiânia, 2019.