Effects of dietary garlic (Allium sativum) and papaya (Carica papaya) leaf powder on production performance, ruminal methanogen levels, gut parameters, and meat quality in goats.

Background and aim: Several approaches have been employed to mitigate methane emissions from livestock, with varied results. This study evaluated the effects of shade-dried ground garlic leaf (GL) powder and papaya leaf (PL) powder as crop waste on feed intake, growth performance, ruminal microbial counts, gut epithelial barrier functions, and meat quality in goats.

Materials and methods: Forty male adult Beetal goats were randomly divided into five treatment groups: (1) Control (basal diet only); (2) basal diet supplemented with 6% bromodichloromethane (BCM); (3) basal diet supplemented with 30% GL powder; (4) basal diet supplemented with 26% PL powder; and (5) basal diet supplemented with 30% GL powder and 26% PL powder (GP).

Results: Average weight gain, feed conversion ratio, fecal score, and albumin improved in the GP. Aspartate transferase increased significantly in BCM, GL, and PL and was insignificant in the GP group compared with the C group. There was a 13% decrease in methanogen count in PL compared with C, but this difference was not significant between BCM and GP. Ruminal bacteria and protozoa were lowest in GL. Ruminal papilla height and surface area increased in the supplemented groups compared with C (p < 0.05). In vitro experiments using isolated ruminal epithelia revealed a 39% increase in short-circuit current in GP compared with C (p < 0.05). For meat parameters, the pH 24 h decreased significantly in GL compared to BCM.

Conclusion: Dietary supplementations with GL and PL alone or in combination improved growth parameters and gut performance and reduced rumen methanogen levels without altering meat quality parameters. Proper diet formulation and further research on other ruminants may help reduce greenhouse gas emissions from livestock.