Estratégias nutricionais para obtenção de bovinos precoces à desmama e ao abate advindos de um sistema de produção de leite em duplo propósito

• Autor(a) principal: Menezes, Gustavo Chamon de Castro
• Data de Publicação: 2014
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1879
• topic: Bovinos - Alimentação e rações; Bezerro - Alimentação e rações; Nutrição animal; Carne bovina - Produção; Bovine - Feeding and animal feed; Calves - Feeding and animal feed; Animal nutrition; Bovine meat - Production; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

This study was maked from an experiment described in the form of two chapters. In chapter 1 the objetive was evaluate the effect of different nutritional strategies in dual- purpose system enhancing the performance of calves and establishing standards to dairy crossbred calves. 60 Holstein x Zebu F1 cows and their calves 3/4 x 1/4 Zebu Holstein were used, distributed in 5 different treatments of nutritional strategies. The strategies used in milk production in dual purpose system consisted of restricted supply daily 1 kg of concentrate per calf. The strategy called short milking period (180 days), normal (270 days of milking) was used. All weaning were performed abruptly when calves reached 270 days of age. The F2 calves were distributed in 12 animals per treatment (5 females and 7 males). The cows were milked twice daily, its production being recorded every 15 days. Cows of group 1, 2 and 3 have been milked for 270 days, with 1 as the control treatment (no concentrated to calves). The calves of treatments 2 and 3 received daily 1 kg of concentrate of 90 to 270 days of age and 180 to 270 days of age, respectively. The cows of treatments 4 and 5 were milked for 180 days and released to pasture with calves that were fed the treatment 4 of 90 to 180 days of age, while in treatment 5, the concentrate was offered to the calves of 90 to 270 days of age. Calves were fed by feeding directly into their mothers before and after milking. The concentrates fed to cows and calves were composed of corn and soybean meal with 20% crude protein. The oxytocin one ml was used to estimate monthly milk intake of calves before and after milking (stimulation milk and residual milk), samples were collected for analysis of components. To estimate the individual intake of forage, indigestible neutral detergent fiber (iNDF) was used as an internal indicator. To estimate the faecal output of calves, the external indicator titanium dioxide was supplied in the amount of 10 grams daily in single dose at 7 am, seven days, and stool samples obtained by rectal palpation during three days in three different times daily. The design of experiment was completely randomized. Data milk intake (stimulus or residual), milk production (composition), nutrient intake, body weight and daily weight gain were calculated for each calf per treatment in each period. All statistical analyzes were performed using the PROC MIXED of SAS (version 9.3) program using 0.05 as the critical level of probability for error type I. The daily intake of milk before milking, the calf was approximately 3 liters. The daily intake of milk after milking the cows was 2 liter per day calf, containing high fat composition. The residual milk after milking has a high somatic cell count. The supply of concentrate to 90 days of age at weaning improved (P <0.05) intake of neutral detergent fiber (NDFap) for treatment 2 calves Calves 5 showed higher intake of milk and protein (P <0.05) and better growth rate. We conclude that patterns of feeding of calves in dual-purpose systems are characterized by the intake of milk in greater quantity of protein before milking and high fat after milking. The best performance of calves is associated with the restricted supply of concentrate in larger period (90 to 270 days of age) and increased availability of milk after 180 days of age. In chapter 2 objetive to evaluate the productive and biological efficiency of dairy steers and heifers for meat production in feedlot. 24 castrated males and 24 females of genetic 3&#8260;4Zebu × 1&#8260;4Holstein were used, with 10 ± 2 months-old males with an average initial body weight of 299 ± 21.9 kg and females 266 ± 41.6 kg. The animals were divided into four periods of confinement: 30, 60, 90 or 120 days with four replications for each sex and slaughtered at the end of each period. The same diet was fed to all animals and consisted of a mixture of 45% corn silage and sugar cane, and 55% of concentrate dry matter basis. The productive and biological analysis was performed by comparative slaughter and dissection of the left half carcass in each period of confinement to determine body composition. The daily intakes of DM, OM, CP and MOD kg had no effect (P> 0.05) interaction between sex and periods in confinement. The heifers had higher intake (P <0.05) of DM, OM and NDFap in grams per body weight and linear reduction in consumption (P <0.05) with increasing days in confinement. Steers had higher (P <0.05) final empty body weight, carcass gain, cold carcass weight and carcass meat proportion, however heifers had higher EGS (P <0.05) and consequently higher (P <0.05) proportion of carcass fat in different periods of feedlot. The RC was lower (P <0.05) after 30 days of confinement for both genders. The quadratic effect (P <0.05) observed for GC, EGS and proportion of carcass fat demonstrates that increasing effect occurred with increasing time in confinement. The proportion of flesh and bone in the carcass showed a quadratic effect with increase in the proportion of time in confinement. Steers and heifers did not differ (P> 0.05) in losses during cooling and length of carcasses. The daily weight gain had an effect (P <0.05) interaction of sex with periods in feedlot. Steers had higher (P <0.05) average daily gain than heifers at 30 and 90 days in feedlot. In the initial phase of 30 days, the steers showed superior performance (P <0.05) compared to the other periods. It is concluded that steers are more efficient in performance than feedlot heifers. To finish the carcass fat cover, heifers need 90 days in confinement. The net energy requirements for maintenance of steers and heifers are 67 kcal / PCVZ0.75 / day and net requirements for energy gain (Elg) and protein (PLg) can be estimated by the equations: NEg (Mcal / day) = 0.067 x PCVZ0,75 GPCVZ1,095e PLg = 162 x EBWG - 5.62 x ER.