Abstract:
Plant secondary compounds are potential rumen modifiers that can improve nutrient
utilization in ruminant animals. This study evaluated the effect of Moringa (Moringa oleifera) and
Neem (Azadirachta indica) leaf extracts on nutrient digestibility, growth performance, and enteric
methane production in South African Mutton Merino lambs. Forty 4-month-old ram lambs with
a mean body weight of 35 2.2 kg were blocked by weight and from each block, lambs were
randomly allocated into one of the following treatments: (i) diet only (fed a total mixed ration TMRnegative
control), (ii) Monensin (fed TMR containing Monensin sodium, 15 mg/kg DM), (iii) Moringa
(fed TMR, drenched with Moringa extract 50 mg/kg feed DM intake), and (iv) Neem (fed TMR,
drenched with Neem extract 50 mg/kg DM intake). Extracts were administered via oral drenching at
a concentration determined based on the previous week’s feed intake. There were no differences in
dry matter intake, average daily gain, feed conversion efficiency, digestibility, and nitrogen retention
across the treatments. However, the extracts tended to reduce methane emitted both in g/head/day
(p < 0.08) and g/ kg dry matter intake (p < 0.07). Extracts did not influence any of the blood metabolites
in the ram lambs. Although the benefits of utilizing these medicinal plants as rumen modifiers under
prolonged feeding conditions is justified, further evaluation is recommended to test Moringa and
Neem leaf extracts at higher inclusion levels. Our research group is currently exploring a variety of
phytogenic tools for the identification and standardization of key bioactive compounds linked to
methane inhibition, in these leaf extracts.
