Feed efficiency indexes in hair sheep: Meat quality and associated genes. Review

Abstract

Hair sheep are essential for meat production in tropical regions, where feed efficiency has been little evaluated. Feed consumption represents more than 70 % of the costs. Therefore, animals with high feed efficiency could increase the profitability of the production system. There exist tools that help select individuals with increased feed efficiency without compromising the quality of the product. This review aims to identify these genetic-molecular and statistical tools, such as residual feed intake (RFI) and residual intake and gain (RIG). Previous studies report differences ranging from 9 to 30 % in the dry matter intake (DMI) of efficient and inefficient animals, maintaining a similar daily weight gain (DWG) using the RFI index. Moreover, the DMI is similar using the RIG index. Although, the DWG of efficient animals is higher by up to 50 g d-1, reducing feed conversion by one kg. This difference is attributed to a group of genes associated with feed efficiency (Adra2a, Gfra1, Gh, Glis1, Il1rapl1, Lep, Lepr, Mc4r, Oxsm, Pde8b, Rarb, Ryr2, Sox5, Sox6, and Trdn). These genes could be used to select hair sheep with high feed efficiency, considering the genes associated with meat quality (Capns1, Cast, Dgat1, Fabp4, Igf-i, Lep, Mstn, and Scd).