Métodos de amostragem de Brachiaria brizantha cv. Marandu, parâmetros nutricionais e desempenho produtivo em novilhos submetidos a diferentes tipos de suplementos

• Autor(a) principal: Alves, Dorismar David
• Data de Publicação: 2006
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1686
• topic: Bovino; Nutrição; Consumo; Suplementação; Plantas forrageiras; Brachiaria brizantha; Bovine; Nutrition; Supplements; Forages plants; Brachiaria brizantha; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::PRODUCAO ANIMAL

The experiment, conducted in a country property in Francisco Sá city, north region of the State of Minas Gerais, aimed at evaluating the methods of sampling of Brachiaria brizantha (Hochst. ex A. Rich.) Stapf cv. Marandu, the nutritional parameters and the productive performance on steers submitted to different types of supplements. The experiment for evaluation of the methods of sampling of the pasture was divided in six periods of 12 days, with total time of 72 days. In the first day of the first experimental period, and so on every 12 days, samplings of the pasture of each paddock were made for qualitative analyses. The samplings were accomplished through the methods of the total determination of dry matter (TDDM), manual simulation of the grazing (MSG) and collection of the extrusa of animals esophagus canulated. The experimental design was in blocks, with three repetitions of the treatments inside of each block, and the methods of sampling of the pasture constituted the treatments and the blocks constituted the dates of sampling. The samples of Brachiaria brizantha cv. Marandu were analyzed as total dry matter content (DM), ashes, crude protein (CP), ether extract (EE), neutral detergent fiber (NDF), insoluble nitrogen in neutral detergent (INND) and in acid detergent (AD), acid detergent fiber (ADF), in vitro dry matter digestibility (IVDMD), indigestible dry matter (iMS), indigestible neutral detergent fiber (iNDF) and indigestible acid detergent fiber (iADF), total carbohydrates (TC), no-fiber carbohydrates (NFC), and fractions of the carbohydrates A + B1, B2 and C. For determination of the dry matter and nutrients consumption, of the nutrients digestibility, pH and concentration of ruminal ammonia in the different treatments, three bovines canulated in the esophagus and rumen were used, being structured the experiment in latin quadrate, with three treatments (concentrate, protein supplement and mineral) and three periods of 12 days each. The latin quadrate was repeated in the time, in the string of the end of the first latin quadrate, for subsequent united analysis of the results. Concomitant to the experiment for evaluation of the nutritional parameters, for evaluation of the productive performance, 18 bovine crossbred Holstein-Zebu were used, with phenotypic characteristic predominantly Zebu, castrated and with average of initial alive weight of 307 kg and approximately 23 months old. The experimental design was entirely randomized, and the animals were distributed at random on paddocks of pasture of Brachiaria brizantha cv. Marandu in three different treatments: mineral treatment, where the animals received mineral supplement at large; protein supplement treatment, with supply of supplement of protein of self-control contends 30,94% of CP and concentrated treatment, where the animals received supplementation in quantities equivalent to 0,73% of the live weight (basis DM) with concentrated contends 20,96% of CP. The average daily gain (ADG) was obtained with basis on the initial and final live weights evaluated after fast of water and foods during 18 hours. When the period of supplementation of the appraised animals as for the productive performance had finished, the procedure of individual weighting of the animals of each treatment was gone on, with the animals just receiving mineral supplement in the pasture, seeking to evaluate the residual effect of the treatments on a possible demonstration of the compensatory growth. The values of live weight of the animals after the withdrawal of the supplementation were submitted to variance analysis and regression. For the results of productive performance, the economical parameters liquid present value (LPV) and benefit/cost relationship were calculated. Regarding the methods of the sampling of Brachiaria brizantha cv. Marandu, all the analyzed variables, except for NFC, were influenced by the treatments, evidencing that the method of sampling of the pasture through extrusa collection, for contemplating the selectivity of the bovine ones in grazing, is what best characterizes the diet of the animals, except for the minerals composition. The determination methods of the total dry matter and manual simulation of the grazing do not characterize the diet selected for bovine in grazing, and the method of determination of total dry matter presents major discrepancy of the method of extrusa collection. The total consumptions of dry matter, in % of the live weight, of CP and no-fiber carbohydrates, in kg/day, were influenced by the treatments, with greater values observed for the concentrated treatment, in relation to the protein supplement and mineral treatment, that differed amongst themselves. The consumption of ether extract and the total digestible nutrients content were influenced by the treatments, with greater values observed for the concentrated, in relation to the protein supplement and mineral treatment, that did not differ amongst themselves. Regarding the productive performance, animals of the mineral treatment presented smaller ADG in relation to the ones of the concentrated and protein supplement treatment, that did not differ amongst themselves. After the withdrawal of the supplementation, during the rainy station, the animals of the protein supplement and mineral treatment presented compensatory growth of the order of 39 and 56%, respectively, in relation to the animals of the concentrated treatment. During the drought, only the treatment with protein supplement presented favorable economic indicators, and the concentrated and mineral ones presented negative results of liquid present value and benefit/cost relationship smaller than 1,0. The economical analysis including the supplementation period and the period after the withdrawal of the supplementation, that correspond to the periods of the dry and rainy stations of the year, respectively, revealed major profitability for the protein supplement, following by the mineral and finally the concentrated treatment.