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| Author(s): |
Flávio Pinto Monção
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Jaboticabal. 2017-06-21. |
| Institution: | Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal |
| Defense date: | 2017-05-25 |
| Advisor: | Gustavo Rezende Siqueira |
| Abstract | |
One hundred and sixty eight young bulls with initial weight of 228 ± 19 kg and age of ten months and twelve Nellore bulls cannulated in the rumen were used to evaluate different nutritional strategies associated with virginiamycin (VM) during the growing phase in pastures of Brachiaria brizantha cv. Marandu on body weight gain (BW), ruminal, blood and urinary parameters and nutrient intake. In addition, evaluate if the benefits provided by the nutritional strategies associated with VM in the growing phase are maintained termination phase in the feedlot in two-time (88 days and 121 days). The growing phase was divided in dry season (08/26/14 to 10/12/14, 105 days) and summer season (10/12/14 to 25/03/15, 105 days) and autumn (25/03/15 to 20/06/15, 87 days), totaling 297 experimental days. The animals received 1 of 4 nutritional strategies: mineral supplement with urea (SU, ad libitum) during dry season and mineral supplement (SM, ad libitum) in summer and autumn; or protein energy supplement in the dry season (SPE, 3 g/kg BW per day), protein supplement in the summer (SP, 1 g / kg BW per day) and SPE in the autumn (3 g / kg BW per day). Within each nutritional strategy, the inclusion or not of VM food additive was evaluated at a dose of 40 mg per 100 kg BW. A randomized complete block design was used in a 2 x 2 factorial scheme, with two strategies of supplementation and presence and absence of VM. The experimental area, divided into 12 paddocks (3.5 to 4.0 ha each), and BW was the blocking factor. 45 animals were used per treatment, divided into 3 paddocks (14 animals more 1 cannulated animal in the rumen per paddock). Early in the growing phase were slaughtered 6 animals to compose the reference group and estimate the animal carcass weight. Each paddock with 14 animals and 1 cannulated animal was the experimental unit. The grazing method adopted was the continuous one. At the termination, the animals were finished for different times ([06/20/2015 to 09/16/2015, 88 days] and [06/20/2015 to 10/19/2015, 121 days]) and received the same diet with 88% concentrate and 12% roughage. Of the one hundred sixty-eight animals used in the growth phase, 24 (6 animals per treatment, 2 animals per paddock) were slaughtered to compose the final reference group of the growing phase and early of termination. During this phase, each experimental unit (paddock with 12 animals and 1 cannulated, because 2 were slaughtered), preserving treatments of growing phase, was divided into two collective pens (6 pens for treatment) in feedlot to be slaughtered with 88 days (3 pens for treatment) and 121 days (3 pens for treatment). For the formation of the pens, the animals of the same picket (experimental unit) were randomly selected. The design was a randomized block in a split plot, 2 x 2 x 2, and two nutritional strategies, presence and absence of VM and two feedlot time (88 and 121 days). The experimental unit was the pen with 6 animals. At the end of the growing phase, SPE/SP/SPE supplemented animals presented higher carcass weight (224 kg vs. 202 kg; P <0.01), carcass weight gain (0.34 kg/day vs. 0.26 kg/day) compared to animals receiving SU/SM/SM. The use of VM provided an additional weight gain of 0.08 kg/day and 0.060 kg/day in animals supplemented with SP and SM, respectively (P < 0.03). The use of VM increased 1.1 percentage unit in the gain yield (P < 0.01), but did not modify the gain in daily gain in carcass (0.31 kg/day; P = 0.36). Animals supplemented with SPE/SP/SPE started the finishing phase 38 kg (22 kg of carcass) heavier compared to animals receiving SU/SM/SM. The VM improves performance of animals only when used in summer, via mineral salt or protein supplement. Most gains provided with additional supplementation with SPE/SP/SPE of grazing animals are kept in the finishing phase. (AU) | |
| FAPESP's process: | 14/24341-4 - Supplementation and use of virginiamycin as modulators of Nellore cattle performance in the rearing phase and its effects on feedlot finishing |
| Grantee: | Flávio Pinto Monção |
| Support Opportunities: | Scholarships in Brazil - Doctorate |