Growth, carcass and sensory characteristics of m. longissimus lumborum from wethers fed silage diets made from maize or various sorghum varieties

Growth, carcass characteristics and eating quality of meat from South Afric an Mutton Merino wethers fed maize or different sorghum silage diets were s tudied. Forty newly weaned wethers (20 kg) were randomly allocated to 10 di etary treatments, viz. non-bird-resistant grain sorghum silage (NGS), maize silage (MS), bird-resistant grain sorghum silage (BGS), forage sorghum sil age (FSS) and a standard non-silage control diet consisting of equal propor tions of maize meal and milled lucerne hay (C). Silage was included at 2 le vels, namely 50% or 70% of the total diet on dry matter basis. Average dail y gains of wethers were recorded from weaning to slaughter at 45 kg live ma ss. Carcass mass, dressing percentage, subcutaneous fat thickness and carca ss length were recorded Samples from the left m. longissimus lumborum were minced and stewed to determine foreign odours and flavours, while samples f rom the right m. longissimus lumborum were oven-roasted for subsequent sens ory evaluation by an analytical sensory panel. Growth responses did not dif fer between wethers fed MS, NGS or BGS at inclusion levels of 50% or 70%. F SS at the 70% inclusion level resulted in poorer growth rates (p < 0.05) an d longer feeding periods (p < 0.05) compared to the other silage diets. The best feed conversion efficiencies and shortest finishing periods were reco rded by feeding MS at either the 50% or the 70% inclusion level, NGS at the 50% inclusion level, or BGS at the 50% inclusion level. Dressing percentag es and subcutaneous fat thicknesses of wethers fed BGS and FSS at a 70% inc lusion level were lower (p < 0.05) compared to those fed the other silage d iets. No significant differences in sensory characteristics or cooking loss es and no sensory defects were observed among wethers fed different silage diets.