Suplementação múltipla para bovinos manejados a pasto em recria e terminação / Supplementation for growing and finishing beef cattle on pasture

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

This thesis was elaborated upon five experiments conducted with the purpose of evaluating the protein supplementation for beef cattle on pature effects on the productive and economic development, and nutritional characteristics. The Experiments 1 and 2 were conducted with the purpose of evaluating the protein sources in supplements for growing crossbred steers in the dry season, and finishing crossbred steers in the dry-rainy transition and rainy seasons, grazing on an area of 6 hectares of Brachiaria decumbens Stapf. divided in 4 paddocks (1.5 ha each) on the productive and economic development. In the Experiment 1 (Dry season), sixteen Holstein x Zebu steers, initially 15 month old and 272 kg 3.7, were randomly allotted to one of four treatments: protein supplements based on wheat bran + cotton seed meal 28% of crude protein (CP) + urea (WBCSU); cotton seed meal 38% CP (CSM); cotton seed meal 28% CP + urea (CSMU); and corn gluten meal 21% CP + urea (CGMU), supplied at the level of 1.5 kg/animal/day (0.55% of body weight - BW). All supplements evaluated showed positive economic income considering the pasture evacuation. In the Experiment 2 (Dryrainy transition and rainy seasons), sixteen Holstein x Zebu steers, 19 month old and 313 kg 4.8, were randomly allotted to one of four treatments: protein supplements with approximately 38% of CP, as feed basis (FB), based on grounded corn grain + urea (GCU); grounded corn grain + soybean meal (GCSB); and cotton seed meal 38% CP (CSM), supplied at level of 0.5 kg/animal/day (0.15% BW), and a mineral mix control treatment (MM). Animals from all treatments received 60 g/day of MM. The animals which received the supplement GCU showed an additional gain of 130 g/day. Supplementation for grazing cattle is a technology that can improve the income; however, the choice of which feedstuffs to use in the supplements formulation has to be based on biologic and market factors. The Experiment 3 was conducted with the purpose of evaluating protein sources in supplements for crossbred steers grazing Brachiaria decumbens Stapf., in the dry-rainy transition season, on the nutritional characteristics. Four Holstein x Zebu steers (300 kg of BW) fitted with esophageal, ruminal, and duodenal cannulas, allotted in a Latin square experimental design 4x4, being four treatments, with four 14 days experimental periods and four repetitions, grazing on four Brachiaria decumbens Stapf. paddocks of 0.4 ha each, were used. The treatments were protein supplements with approximately 38% of CP, as FB, based on grounded corn grain + urea (GCU); grounded corn grain + soybean meal (GCSB); and cotton seed meal (38% CP) (CSM), supplied at a level 0.17% BW, and a control treatment MM. All animals in the experiment received 60 g/day of MM. The animals that received the treatment GCU showed neutral detergent fiber (NDF) intake of 12.1 g/kg of BW, 19.95% greater than (P<0.10) the observed on the animals that received the treatments MM and GCSB, 10.2 g/kg of BW, and similar than the NDF intake found to the treatment CSM, 11.0 g/kg of BW. The dry matter (DM) total apparent digestibility (TAD) was greater (P<0.10) on the treatments GCU and GCSB, being superior 7.99 and 6.25% to the MM treatment, respectively. The ruminal pH, microbial nitrogen production, and microbial synthesis efficiency were not influenced (P>0.10) by the treatments. The supplementation with corn and urea provided greater DM intake and total apparent digestibility, compared to the mineral mix, and numeric increase of 16.43% in the pasture DM intake. Thus, the use of supplements based on corn and urea during the dry-rainy transition season, at the level of approximately 0.17% of BW, it is suggested. The Experiment 4 was conducted with the purpose of evaluating the different protein sources for growing Nelore steers during the dry-rainy transition and rainy seasons, grazing Brachiaria brizantha, variety Marandu, on the productive and economic development. It was used twenty Nelore steers, initially 12 month old and 196 kg 2.2, randomly allotted in four groups with similar weight, kept in four paddocks (1.5 ha each) of Brachiaria brizantha, variety Marandu. It was evaluated protein supplements, formulated to contain 38% of CP, as FB, based on disintegrated corn with cob + urea/ammonium sulfate (DCCU); toasted soybean (TS); and cotton seed meal 38% CP (CSM), daily supplied at 10 AM at a level of 0.5 kg/animal, corresponding to approximately 0.25% of BW, and a control treatment MM. Animals from all treatments received 60 g/day of MM. It has not been found differences (P>0.10) for the final empty body weight and average daily gain (ADG) among the different treatments, and it has been observed the mean values of 318.7 kg and 1.093 g/day, respectively. However, it has been observed a numerical increase of 132 g in the ADG for the animals that received the treatment TS compared to the animals who received the treatment MM. The supplement based on toasted soybean, supplied to growing animals during the dry-rainy transition and rainy seasons, in amount similar to 0.25% of BW, propitiated numerical increment of 132 g on the ADG, compared with the mineral mix, and positive economic income. The Experiment 5 was conducted with the purpose of evaluating protein sources in supplements for crossbred steers grazing Brachiaria brizantha, variety Marandu, in the rainy season, on the nutritional characteristics. Four Holstein x Zebu steers (300 kg of BW) fitted with esophageal, ruminal, and duodenal cannulas, allotted in a Latin square experimental design 4x4, being four treatments, with four 14 days experimental periods and four repetitions, grazing on four Brachiaria brizantha, variety Marandu, paddocks of 0.4 ha each, were used. The treatments were protein supplements with approximately 38% of CP, as FB, based on disintegrated corn with cob + urea/ammonium sulfate (DCCU); toasted soybean (TS); and cotton seed meal 38% CP (CSM), daily supplied at 10 AM at a level of approximately 0.17% of BW, and a control treatment MM. Animals from all treatments received 60 g/day of MM. The nutrients intake was not influenced (P>0.10) by the supplements used, with exception for the one observed on the ether extract (EE). It was found a negative value to the CP ruminal apparent digestibility (RAD) for the animals that received the treatment MM, being lower to the ones (P<0.10) observed on the treatments DCCU and TS. The ruminal pH, urinary excretions of ureic nitrogen, urinary excretions of urea, nitrogen microbial production, and microbial synthesis efficiency were not influenced (P>0.10) by the treatments. It is concluded that possibly occurred a quantitative deficiency of nitrogen compounds in the rumen that maximized the microbial activity and growth which is an evidence of the need for protein supplementation in the rainy season.

ASSUNTO(S)

parâmetros nutricionais beef cattle ganho de peso nutricao e alimentacao animal bovino de corte performance desempenho nutritional parameters weight gain

ACESSO AO ARTIGO

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