GHG production and energy partitioning in female and male Somali sheep under different diets

Abstract

The objective of this work was to evaluate greenhouse gas (GHG) production and energy partitioning in growing female and male Brazilian Somali sheep subjected to different diets. The experiment was completely randomized, in a 3×2 (three diets combining crude protein and total digestible nutrients x sex classes) factorial arrangement, with four replicates. The factorial analysis of variance was used, and means were compared by Tukey’s test. GHG emissions and energy partitioning were determined using open-circuit respirometry chambers. No effect of sex was observed. Sheep fed the diet that met 100% of the recommendations of National Research Council (NRC) showed a higher gross energy intake, digestible energy intake, oxygen consumption, carbon dioxide production, heat production, and respiratory quotient than sheep fed the diet that met only 85%. However, both diets showed similar results for gross energy loss via feces, metabolizable energy intake, energy balance, metabolizability, metabolizable:digestible energy ratio, and daily methane production. The net energy requirement of Brazilian Somali sheep did not differ between sex classes during their early growth phase. At this phase, the diet that met 85% of the NRC recommendations can be used instead of the one that met 100%, without reducing energy efficiency or increasing methane emissions.