Effects of supplementation on performance and nutritional and metabolic aspects of beef cows and calves at pasture

• Ano de defesa: 2017
• Autor(a) principal: Martins, Leandro Soares
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Bovinos de corte - Alimentação e rações; Nelore (Bovino); Bezerros; Nutrição animal; Pastagens; Avaliação de Alimentos para Animais
• Link de acesso: http://www.locus.ufv.br/handle/123456789/10414

For the thesis composition were prepared three scientific articles based on studies with dams of Nellore breed and their respective calves, submitted to different supplementation schedules in different phases of production. In the first article the objective was to evaluate the effect of Bos indicus dams’ supplementation in the pre and/or post calving period, on the performance of their male and female calves in the suckling phase. Eighty four pluriparous Nellore cows (body weight (BW) of 522 ± 9 kg and body condition score (BCS) of 5 ± 0.08 (1-9 scale)) and their calves (44 females and 40 males) were used. The dams’ treatments were: 1 kg of supplement during 90 days before and 90 days after calving (Supplemented all time), 1 kg of supplement during 90 days before calving and mineral mixture after calving (Supplemented before calving), mineral mixture before calving and 1 kg of supplement during 90 days after calving (Supplemented after calving) and a control treatment, receiving only mineral mixture ad libitum during entire experiment (Control). Cows supplemented before calving, calved heavier calves than supplemented after calving group. No differences were observed in BW at weaning, cows’ BCS and cow’s milk production (P > 0.05). Dams from the Control treatment had smaller milk fat in the first milk collection in the calves’ supplementation period, when contrasted with the supplemented groups (P < 0.05). Male calves of cows from the Control treatment showed higher (P < 0.05) dry matter intake (DMI) than sons of supplemented cows’ groups (average of DMI was: 5.5 kg and 3.4 kg to male calves of cows from Control treatment and cows which received supplement, respectively). No differences were found among the different dams’ treatments to T3, T4, glucose, rib eye area (REA), subcutaneous fat thickness (SFT), Gluteus medius depth (GMD) and P8 thickness fat (P8TF) of male calves. Daughters of cows from the Control treatment showed lower serum glucose, but had greater serum urea compared to daughters of supplemented dams. It was concluded that supplementation of cows before calving improves calves’ birth weight and the non-supplementation in the pre/post calving increase the male calves’ DMI during suckling phase. In the second article was evaluated the effect of different schedules of multiple supplementation on performance and carcass composition during the suckling phase of grazing Nellore male calves, as well as the influence of this supplementation schedule on performance of these animals in the feedlot. Forty-eight Nellore male calves (147 ± 7 kg BW and 3 months of age) in the suckling phase and their dams (512 ± 9 kg BW and 6 years of age), were used in a completely randomised design. The supplementation period was 142 days in duration and consisted of two equal 71 day periods (1 and 2), followed by a 125 days feedlot period. The treatments were: 5 and 10 g supplement dry matter (DM)/kg BW.day offered in period 1 and 2 respectively (5S/10S); 10 and 5 g supplement DM/kg BW.day offered in period 1 and 2 respectively (10S/5S); 7.5 g supplement DM/kg BW.day in both periods 1 and 2 (7.5S) and mineral mix ad libitum in both periods 1 and 2 (MM). Supplemented calves showed greater final BW and ADG (0.900 kg and 0.560 kg, the ADG in the suckling phase of supplemented and unsupplemented calves, respectively; P < 0.05), during the first and second experimental period. Calves from 5S/10S and 7.5S showed higher final BW and total ADG than calves from 10S/5S. No differences in ADG and FBW were observed in the first phase among supplemented calves. Animals from MM presented smaller (P < 0.05) rib eye area (REA), subcutaneous fat thickness (SFT) and Gluteus medius depth (GMD). In the feedlot period, supplemented animals had greater initial (P < 0.05) BW and tendency (P < 0.10) of greater final BW. It was concluded that male calves supplemented during the suckling phase, show better performance at weaning. The amount of 7.5 g supplement DM/kg BW.day is recommended to improve the performance. In the third article the aim was to evaluate different schedules of supplementation at pasture to calves in a creep feeding system, as described in the second article, on dam’s performance and behaviour of calves and their dams. No differences (P < 0.05) in BCS, final BW and ADG were found on dams’ performance. Calves from MM treatment spent more time (P < 0.05) grazing than supplemented calves from 5S/10S and 10S/5S treatments, in the first period. No difference in suckling time was found among the treatments (P > 0.05) in the first evaluated period. Calves from 10S/5S treatment spent more time suckling and less time eating supplements (P < 0.05) than 5S/10S treatment animals, in the second evaluated period. Dams of MM treatment’s calves showed more idle time and lower grazing time when compared with the mothers of calves from 5S/10S and 10S/5S treatments. It was concluded that, different schedules of Nellore calves’ supplementation at pasture, do not affect their mothers’ performance, and supplementation decreases grazing time of calves in the suckling phase.