Abstract:
There is an increased interest in the use of medicinal plants as alternatives to antibiotic
growth promoters and as agents for methane production mitigation. This study investigated the
effects of Azadirachta indica and Moringa oleifera feed additives on the carcass and meat quality of
lambs. Forty South African Mutton Merino lambs, weighing between 29 and 43 kg, were randomly
assigned to four treatment groups (n = 10 lambs/treatment) and fed a basal total mixed ration (TMR)
containing soybean meal (17%), yellow maize (28%), Alfalfa hay (20%), Eragrostis curvula hay (22.2%),
molasses (6.0%), wheat offal (5%), urea (0.8%) and vitamin premix (0.5%) on a DM basis. The dietary
treatments: TMR diet (control); TMR diet with A. indica leaf extract (A. indica leaf extract at a dosage of
50 mg per kg of feed: neem); TMR diet with M. oleifera leaf extract (M. oleifera leaf extract at a dosage
of 50 mg per kg DM of feed: moringa); TMR diet with monensin (at a dosage of 50 mg monensin
sodium per kg of feed: positive control). After an adaptation period of 10 days to the experimental
conditions, the lambs from all treatment groups were fed ad libitum with the experimental diets. The
lambs were slaughtered at a live weight of 60–65 kg after a 23 week trial period. The plant extract
dietary additives had no significant effects on the carcass characteristics of the lambs. In comparison
to monensin, supplementing with moringa leaf extracts resulted in a higher proportion of C18:1n9c
(45.0% 0.57 vs. 40.5% 0.80; p < 0.05), total MUFAs (47.3% 0.66 vs. 42.6% 0.87; p < 0.05),
and UFA:SFA ratio (1.01 0.03 vs. 0.85 0.03; p < 0.05), which may be beneficial for human health.
Our results suggest that natural feed additives, such as A. indica and M. oleifera leaf extracts, can be
included in lamb diets without compromising meat fatty acid composition. The negative economic
impacts of such technologies on animal production and farm profitability should not be expected.
