Productive performance and ingestive behavior of crossbred heifers in integrated livestock-forest systems

Abstract

The present study aimed to assess the productive performance,ingestive behavior,and thermal condition of crossbred beef heifers in an integrated livestock-forest (ILF) system with different tree-planting designs. Seventy-two ½ Angus ½ Nellore heifers were divided in three treatments–conventional system (CS) without eucalyptus,integrated livestock system with 187 eucalyptus ha−1 (ILF-1L),and integrated livestock system with 446 eucalyptus ha−1 (ILF-3L)–,in the winter and summer. Total dry mass of forage (TDM),chemical analysis of Marandu palisadegrass,average daily gain (ADG),stocking rate (SR),weight gain per area (WGA),behavior,microclimatic variables,and thermal comfort indexes were evaluated. A higher percentage of crude protein and lower TDM and SR were observed in ILF-1L and ILF-3L,with no differences for ADG and WGA. Ambient temperature,temperature-humidity index,black globe-humidity index,and radiant heat load were better in ILF-1L and ILF-3L. Heifers in ILF-1L and ILF-3L carried out grazing,resting,rumination,and other activities in the shade. In the summer,heifers in ILF-1L and ILF-3L spent less time resting and more time in rumination and performing other activities than those in the CS. In conclusion,the better forage quality in ILF-1L and ILF-3L does not alter the performance of heifers or WGA,despite the decreased TDM and SR. Furthermore,ILF-1L and ILF-3L provide better thermal comfort,and heifers that do not have access to shade decrease their activities as a strategy to reduce the use of energy for thermal regulation process.