Enteric methane emission, feed efficiency and digestibility of Nellore cattle
Abstract
The project aims to evaluate the effect of different levels of metabolizable protein supply in the growing on performance, protein metabolism and emission of greenhouse gases (methane emissions (CH4), nitrous oxide (N2O) and volatilization of ammonia (NH3)), as well as effect of preconditioning beef steers rearing on finish of beef cattle in Brazil, in two typical scenarios (feedlot or supplemented grazing). Studies to date have focused investigations especially for finish systems, without considering the effects of nutrition during rearing on the subsequent performance in finish. The main aspects will be studied: N2O, NH3 and CH4 emission by excreta of grazing and feedlot animals, as well as performance, protein metabolism, carcass characteristics and meat quality from animals undergo to different treatments in two scenarios. Four experiments will be carrying out: The first to evaluate protein metabolism and kinetics of urea in cattle fed concentrate-based diets with different metabolizable protein levels. The second study will evaluate performance, protein metabolism and greenhouse gases in weanling animals, during the growing period, with or without protein supplemented grazing. The third and fourth study will comprise 2 typical beef cattle production scenarios: finish in feedlot or in pasture coming from two different preconditioning beef steers rearing. In the first study, metabolism, will be assessed the intake and digestibility of nutrients, ruminal and blood parameters, kinetics of urea, efficiency of use of amino acids, nitrogen balance (N) and N excretion in feces and urine . In the second study will assess the performance, feed efficiency, intake and digestibility of nutrients, ruminal parameters, N excretion in feces and urine and loss of CH4, N2O and NH3 excreta in pasture. In the third study will assess supplementation in pasture on performance, feed efficiency, intake and digestibility of nutrients, ruminal parameters, N balance, carcass characteristics, meat quality, and the loss of CH4, N2O and NH3 excreta in pasture. In the fourth study will assess the performance, feed efficiency, intake and digestibility of nutrients, ruminal parameters, the balance of N, carcass characteristics, meat quality, N balance and loss of CH4, N2O and NH3 excreta in feedlot. Our hypothesis is that the increase supplementation with metabolizable protein during of preconditioning of rearing, reduces the time of finished, influence carcass and meat quality and changes the emission of greenhouse gases during the animal production cycle. The results of this proposal will allow the design of nutritional strategies to optimize animal performance with reduced environmental impact of cattle production, especially for increasing N use efficiency in typical beef cattle production scenarios in Brazil. (AU)