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Crossbreeding, biotechnics and Management Strategies for Sustainable Intensive Beef Production Systems


Beef production in Brazil has been attained mainly in extensive systems on pasture, where the animals, generally of low genetic potential, are exposed to a seasonal lack of forage and little health control. Intensive beef production can contribute significantly to the Brazilian beef industry, since it favors the rational utilization of the production factors and the potential and genetic diversity of plants and animals. However, it is necessary to generate and adapt suitable technologies, capable of improving the production level in a sustainable manner. The objective of this project is to evaluate, biologically and economically, different options of beef production systems, to improve beef production and productivity by intensification of the systems. The project intends to quantify the difference among alternatives of production and crossbreeding systems, for biological and economical traits, to provide different options of genetic resource utilization and of feed and management practices to raise the productivity of the whole beef production system, and to develop mathematical models to estimate performance of animals, nutrient flux, and economical results of different systems. The project includes the evaluation of breeds and crossbreeding, representing different biological types of cattle, and feeding and management practices, considering the production and crossbreeding systems as a whole and not only its several phases separately, in an effort that will allow system modeling and simulation of the results. The project will be executed at the Southeast - Cattle Research Center (CPPSE) of the Brazilian Agricultural Research Corporation (Embrapa), in São Carlos, SP, at the "Luiz de Queiroz" College of Agriculture (ESALQ) of the University of São Paulo (USP), in Piracicaba, SP, at the State of São Paulo Animal Science Institute (IZ/SP), in Nova Odessa, SP, and at the São Paulo State University at Jaboticabal (UNESP/Jaboticabal), in Jaboticabal, SP. It contains eight experiments described ahead. The objective of experiment 1 ("Evaluation of different beef cattle crossbreeding systems") is to evaluate the biologic and economic efficiencies of some beef cattle crossbreeding systems, representing different biological types. Five different 6 systems will be evaluated: SNR, a straight bred Nellore system, under extensive management (1. 0 AU/ha; this is the control system); SNI, a straight bred Nellore system, under intensive management (5. 0 AU/ha); SRCI, a rotational Canchim-Nellore system, under intensive management; STSI, a terminal three-cross of Simmental-Nellore with Canchim or Limousin, under intensive management; and STAI, a terminal three-cross of Aberdeen Angus-Nellore with Canchim or Limousin, under intensive management. The systems will be evaluated for growth, maternal ability, reproductive efficiency, carcass, parasite resistance, total productive efficiency, and animal behavior. Biologic and economic evaluations will be made. The experiment was initiated in 1997 and by the year 2000 the performance of the Nellore and F1, animals will be quantified. The objective of experiment 2 ("Feeding and management strategies to reduce the age at first breeding and to increase female reproductive efficiency") is to evaluate feeding and management alternatives for the females of the different genetic groups produced in experiment 1, in order to increase productivity of the female herd, by the intensification of the system. The experiment will begin in 1998 and finish in 2001. The objective of experiment 3 ("Feeding and management strategies for males of different genetic groups to produce young cattle, on pasture and feedlot") is to evaluate feeding and management alternatives for males of the different genetic groups produced in experiment 1, to obtain carcasses classified as young, with slaughter occurring between 14 and 18 months of age. The experiment will begin in 1998 and finish in 2001. The objective of experiment 4 ("Study of the etiology of neonatal diarrhea in beef calves") is to study the etiology of calf diarrhea and to propose a standard emergency treatment. It will use the Nellore and F1, calves produced in experiment 1, born in 1998 and 1999. The objective of experiment 5 ("Performance, chemical composition of empty body, physical composition of the carcass, and energy, protein and macromineral requirements of cattle for growth, finishing, maintenance, gestation and lactation") is to determine the energy, protein and mineral requirements for growth, and energy requirement for maintenance, gestation and lactation for the cattle of the different genetic groups produced in generation 1 of experiment 1, and to develop mathematical models to estimate animal performance and the nutrient flux, allowing the identification of more efficient feeding and management strategies for the intensification of beef cattle production systems. The objective of experiment 6 ("Cow-calf relationship during the first hours after calving") is to study the establishment of the cow-calf relationship and the behavior of the newly-born, and their effects on calf survival and growth, for the different genetic groups produced in experiment 1. The objective of experiment 7 ("Evaluation of the genetic distance among cattle breeds and its relationship with heterozygosity and performance") is to evaluate the existence of correlation between genetic distance of the parents and heterozygosity in the progeny, and between heterozygosity and performance in the progeny. It will be executed along with experiments 1, 2 and 3, using the same animals. The objective of experiment 8 ("Evaluation of the environmental impact on intensive pasture beef cattle systems, to optimize the sustainable use of the natural resources") is to see if the intensive management of beef cattle causes negative impact on the hydraulic and chemical characteristics of the soil. The experiment will be accomplished by monitoring the soil of the SNR and SNI systems of experiment1. It was initiated in 1997 and will be finished in 2001. Among the expected benefits that will arise from the project are an increase in production and productivity, the avoidance of seasonal production, and an increase in quality of beef. The results will be spread by a variety of strategies that will make use of the available communication means. Livestock production professionals, as well as undergraduate students will be trained. Several graduate students will make use of the data obtained in the project to do their thesis and dissertations. (AU)

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