Production of Angus-Nellore heifers in integrated crop-livestock systems

Abstract

Integrated Crop Livestock Systems (ICLS), in the different formats, are a viable alternative to the increasing demand for environmentally adequate products. One of the modalities of ICLS are the silvopastoral systems, which has the participation of the animal, arboreal and forage component. The trees act in the control of erosion, improvement of fertility by the accumulation of organic matter in the soil, through the participation of leaves and branches, benefiting the nutrient cycling. Other benefits of using trees in pasture are the diversification of property income, contribution to carbon sequestration, also providing shade to the animals, improving thermal comfort, with impacts on the performance and meat quality. The objective of this study will evaluate the pasture characteristics, performance, behavior, carcass and meat quality crossbred heifers Angus-Nellore in silvipastoral systems with two densities of trees (196 and 448 eucalyptus trees ha-1) and conventional pasture. The experiment will be conducted in APTA - Andradina, SP. The treatments: conventional pasture; silvopastoral systems with 196 eucalyptus ha-1 and silvopastoral systems with 448 eucalyptus ha-1. Seventy two heifers Nelore-Angus will used in experimental randomized blocks with 3 treatments and 4 repetitions (24 animals for treatment). For the evaluations, the winter and summer seasons will be used and the following analyzes: a) Forage evaluation: the total dry mass and grazing simulation; b) Animal performance: daily weight gain, weight gain per area and stocking rate per area. c) Behaviour evaluations: will be made by instantaneous and continuous sampling with focal sampling and sampling interval of 10 minutes, directly, for continuous periods of 12 hours. The behaviors will observed: grazing, rumination (standing and lying), idle (standing and lying), and other activities (interaction with other animals, interaction with trees, behavior of drinking water, going to supplement trough, urinating and defecating, displacement and others). d) Thermal comfort: On the same day of the behavior bioclimatic data will evaluated: black globe temperature, temperature and relative humidity, wind speed, in the winter and summer seasons. The thermal comfort indexes will calculated: temperature and humidity index, black globe temperature and humidity index, radiant thermal load index. e) Carcass quality: ribeye area, fat thickness, weight carcass, carcass yield, fat cavity. f) Meat quality: marbling, tenderness, color, chemical composition and pH. The data will submitted to statistical analysis using the R program for the implementation of the analysis of variance and Tukey's test at a significance level of 5 %. (AU)