Crescimento de bovinos de corte no sistema pasto/suplemento submetidos a diferentes planos nutricionais

• Autor(a) principal: Paula, Nelcino Francisco de
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1812
• topic: Bovinos; Exigências nutricionais; Pasto; Suplementos; Cattle; Nutritional requirements; Grazing; Supplement; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

Four experiments were conducted to evaluate the effects of different nutritional plans on growth of beef cattle of the suckling to slaughter, and body weight (BW) change, and nutritional characteristics of non-pregnancy cow. In experiment 1 evaluated intake, digestibility, microbial protein synthesis, and productive performance of beef cattle crossbred (at last 50% Nellore cross) with initial age of 120 day and shrunk BW (SBW) 132.5±5.4 kg. The animals (44) were divided into four groups and grazed Urochloa decumbens. They received different four supplementation strategies in four production phases: transition rainy-dry, dry, transition dry-rainy and rainy. The animals were randomly assigned to one of four nutritional plans of supplementation: mineral only, low, medium, or high supplement intake. There was increase in the intake of nutrients, but decrease in dry matter forage intake (DMFI), with increase of the supplementation. In general, the digestibility increased with supplementation. The increase in the supplementation, increase the nitrogen excretion. Overall, was observed that high supplementation increase the final BW of animals with slaughter weight of 359, 365.9, 397.5, and 443 for control, low, medium, and high respectively. The average daily gain of high supplementation was biggest in all production phases with values of 0.807, 0.633, 0.560, and 0.776 in the transition rainy-dry, dry, transition dry-rainy and rainy production phase respectively. The supplementation allowed increase in weight, carcass dressing, and commercial cuts when compared to animals control group, with larger values to high supplement intake. In experiment 2, evaluated the energy requirement the energy requirement for maintenance and weight gain and net protein requirement for weight gain of beef cattle crossbred under tropical grazing conditions. It used the same animals and nutritional plans of the previous experiment. Four animals were slaughtered as reference and the remaining were slaughtered serially in the different phases. The average relation between empty BW (EBW) and SBW was 0.910 and between EBW gain (EBWG) and average gain day (AGD) was 0.907. The net and metabolizable energy requirements are 68.5 kcal/EBW0.75 and 124 kcal/EBW0.75, respectively. The efficiency of metabolizable energy utilization for maintenance and BW gain is 0.5524 and 0.24, respectively. The net energy weight gain (NEWG) can be obtained by equation: RE = 0.035× EBW0.75 × EBWG0.5653 and the net protein weight gain (NPWG) by equation: RP = 18.6722 + 78.6388 x EBWG + 31.9809 x RE. The experiment 3 was conducted to develop equations to predict carcass and body fat compositions using biometric measures (BM) and body postmortem measurements. It used the same animals, nutritional plans and slaughter protocol of the previous experiment. The day before each slaughter, animals were weighed and BM were taken, including hook bone width (HBW), pin bone width (PBW), abdomen width (AW), body length (BL), rump height (RH), height at withers (HW), pelvic girdle length (PGL), rib depth (RD), girth circumference (GC), rump depth (RuD), body diagonal length (BDL), and thorax width (TW). Others measurements included were total body surface (TBS), body volume (BV), subcutaneous fat (SF), internal fat (InF), intermuscular fat (ImF), carcass physical fat (CF), empty body physical fat (EBF), carcass chemical fat (CFch), empty body chemical fat (EBFch), fat thickness in the 12th rib (FT), and 9 11th rib section fat (HHF). The BM improved estimates of TBS. The data indicate that BM in association with SBW were precise in accounting for variability of SF, InF, CF, EBF, CFch, and EBFch. Furthermore, the development of an equation using HHF as predictor, in combination with SBW, was a better predictor of CF and EBF than using HHF by itself. The experiment four was conducted to evaluate the effect of level different of low intake supplements on BW change, body condition score (BCS), intake, digestibility and microbial efficiency of non-pregnancy cow, crossbreed, with zebu blood predominance and initial BW of 394.7±13.14 kg in Urochloa decumbens during dry season. Four treatments were evaluated: Control (without supplementation), T250, T500, and T750, corresponding 250, 500, and 750 g of supplement/animal/day, respectively. The average was 409.8 kg, 0.181 kg, and 4.85 point for final BW, AGD, and BCS respectively. There was increase of the intake of crude protein (CP), non-fibrous carbohydrates, and ether extract (EE) with the level supplementation. The average total dry matter intake was 20.31 g/kg of BW. The digestibility coefficients dry matter, organic matter, neutral detergent fiber, and total digestible nutrients showed a quadratic response and a linear effect on digestibility coefficients of the CP and EE according supplementation level. The supplementation level not influenced the microbial protein synthesis.