Effects of dietary Acacia mearnsii tannin additives as methane mitigation agents on the carcass characteristics of lambs

Abstract

Ruminants emit methane which is a concern worldwide as it is linked to global warming. Supplemental methane mitigation strategies can't be imple- mented unless their risks and benefits on carcass quality are known. Past research suggests that the addition of tannins to the diet as a methane mitigation agent could potentially have co-benefits in terms of meat quality and carcass character- istics. The effects of the dietary tannin additive on the meat quality and carcass characteristics of the Dohne Merino sheep were determined. It included meat col- our and long chain fatty acid (LCFA) profile of the carcass (intramuscular and subcutaneous fat). 40 Dohne Merino ram lambs were randomly assigned to one of the four treatment diets. The diets consisted of total mixed ration (TR) and the respective test additive. Treatment one - TMR only (C); Treatment two - TMR +75 mg/kg of Rumensin (Monensin being the active ingredient) (M); Treatment three - TMR + crude Acacia mearnsii tannin (20 g/kg feed) (CT) and finally treat- ment four - TMR + encapsulated Acacia mearnsi tannin (20 g/kg feed) (ECT). The meat colour was not significantly affected by the tannin additives but the LCFA profiles differed significantly for intramuscular FA of treatment groups. C18:2n6t (linoleic acid), C18:3n3 (linolenic acid), C22:6n3 (docosahexaenoic acid) and C21:0 (heneicosanoic acid) all showed significant differences (P<005) between treat- ments, with both tannin treatments having the highést concentration. If dietary tannin additives as methane mitigation strategies are successful in lowering the carbon footprint significantly, it can confidently be concluded that Acacia mearnsit tannin treatment groups showed significant effects on intramuscular FA compo- sition, specifically for beneficial UFA