Concentração de proteína e cronologia de fornecimento de suplementos para bezerros lactentes sob sistema de creep feeding

• Autor(a) principal: Zamperlini, Belmiro
• Data de Publicação: 2008
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1714
• topic: Conversão; Bovino de corte; Digestibilidade; Desempenho de bezerros; Conversion; Beef cattle; Digestibility; Calve performance; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::PRODUCAO ANIMAL

This work was developed based on three experiments with calves and milking Nellore cows in pasture of Brachiaria decumbens. In Experiment 1 the productive and economic performance of Nellore calves in milking phase receiving supplements with different protein concentrations were evaluated in an area of Brachiaria decumbens pasture. Forty milking Nellore calves with mean body weight of 119.6 kg and mean age of three months were distributed in four paddocks of 10 hectares each, with a mean digestibility of dry mater and potential digestible dry matter of 3.27 and 1.95 t/ha, respectively, in a completely randomized design, in four treatments. The calves received with restriction to randomization as a function of sex, one of the following treatments: T1 untreated control group (mineral mixture - MM); T25 supplement with 25% CP; T30 supplement with 30% CP and T35 supplement with 35% CP, furnished daily in the amount of 60 g/animal of MM and 500 g/animal of the other supplements. The mean intake of supplement was 221.6 grams/calf/day and mineral salt 30 grams/calf/day. The mean milk production of the cows was 3.18 kg per day, with 3.64% of protein; 4.12% of fat and 12.68% of total solids. The animals that received multiple supplement presented superior performance than those that received mineral mixture; the supplement with 30% crude protein caused a differential of 57 g/day in relation to the others. In relation to price of equilibrium the T30 is viable when the price of supplement is up to 69.9% of the cost of kg of calf. It is recommended the furnishment of supplement containing 30% CP for calves during the growing phase. In Experiment 2 the productive and economic performance, the intake and digestibility were evaluated in milking Nellore calves, supplemented with different chronologies in an area of Brachiaria decumbens pasture. For evaluation of productive performance forty Nellore calves with age and mean live weight of 30 days and 67.53 kg, respectively, being six males and fours females per treatment, suckling in commercial Nellore cows with around five years of age, were distributed in four paddocks of 10 hectares each, with mean availability of dry matter and potential digestible dry matter of 4.42 and 2.64 t/ha, respectively. The calves received with restriction to randomization as a function of sex, one of the following treatments: MM, mineral mixture after 30 days of age; DEC (December) supplement after 30 days of age; JAN (January) supplement after 60 days of age and FEB (February) supplement after 90 days of age. The mean milk production of the cows was 3.87 kg per day, with 363% of protein; 4.58% of fat and 12.55% of total solids. The voluntary intake, in kg/day was affected by supplementation (P<0.10), except to intakes of EE and total digestible nutrients (P>0.10). The supplementation stimulated the total pasture intake and reduced milk intake (P<0.10). The total digestibility coefficients did not differ among the supplementation conditions (P>0.10). The supplementation of milking beef calves in creep feeding system after January, corresponding to 60 days of age increases the productive and economic performances of the production system. In Experiment 3 the biometric characteristics and milk production and composition of beef cows as a function of the sex of calves were evaluated. For evaluation of productive performance, forty commercial Nellore cows plus their calves, with mean age of five years and mean body weight of 435.1 kg were used. The mean body condition score (BCS 1 to 9) in the beginning of the experiment was 5.08. The cows were distributed in four paddocks of 10 hectares each, with total dry matter availability of 4.42 t/ha and potential digestible dry matter of 2.64 t/ha. The milk production of the cows were not affected by the treatments that the calves were submitted (P>0.10). There was significant effect of time on milk production (P<0.10). The mean milk production of the cows on December to May was 3.13 kg/day, projecting total production during the experimental period of 643 kg of milk. The mean composition of solids of milk for protein, fat, lactose and dry extract were 4.30%, 4.22%, 4.38% and 11.22%, respectively. There was effect of treatment applied to the calves on the final weight of the cows (P<0.10). The milk production by Nellore cows in pasture is influenced by the sex of the calves, being greater for males with possible reflexes of greater demand by nutrients in comparison with females. The body condition of the cows after the milking phase presents negative association with the performance of calve.