The effect of fibre source in finishing diets on lamb performance and muscle fatty acid composition

Abstract

The objective of this study was to evaluate the effect of dietary fibre sources on the performance, carcass characteristics, and muscle fatty acid composition of finishing lambs. Fifty-eight Merino ram lambs were randomly allocated to nutritionally similar treatment diets differing mainly in fibre source: i.e., lucerne hay (LH - 350 g/kg), soybean hulls (SH - 229 g/kg), maize stover (MS - 195 g/kg) and Eragrostis tef (ET - 216 g/kg). The animals were slaughtered on day 78. Growth performance and carcass characteristics were determined. Meat samples were taken from the Musculus longissimus dorsi for fatty acid determination. Lucerne hay resulted in a higher dry matter intake (1604 g/day), metabolizable energy intake (14.43 MJ/day), average daily gain (315 g/day), cold carcass weight (24.93 kg), and dressing percentage (47.48%). Total n-6 muscle content (7.99%) was low following lucerne hay inclusion compared only to treatment ET (10.01%). Lucerne hay resulted in a higher α-linolenic acid (0.79%) and total n-3 (1.24%) muscle tissue content which resulted in a decrease in the n-6:n-3 ratio (6.42). In the present study it was proven that fibre source in nutritionally-similar diets can influence growth performance and the fatty acid profile of lamb meat.