Dietary supplementation with papaya (Carica papaya L.) leaf affects abundance of rumen methanogens, fermentation characteristics and blood plasma fatty acid composition in goats

Abstract

The objective of this study was to test the effect of feeding papaya leaf (PL) on rumen microbial population, fermentation characteristics, blood fatty acid composition and antioxidant activity in goats. Three rumen fistulated male goats were assigned in a 3×3 latin square design using three levels of PL: no addition of PL in basal diet (control, CON, 50% concentrate + 50% alfalfa hay), 25% of alfalfa hay in basal diet replaced by PL (medium PL, MPL) and 50% of alfalfa hay in basal diet replaced by PL (high PL, HPL). Rumen fluid and blood plasma were sampled from the animals at the end of feeding trial (third week). Papaya leaf treatments (MPL and HPL) showed significant differences (p<0.05) in terms of rumen fermentation parameters as compared to the CON group at different times of measurement. The concentration of methanogenic archaea (log10cell/L) decreased (p<0.05) in both PL treatment groups as compared with CON group at all sampling times. The concentration of α-linolenic acid and total conjugated linoleic acid (CLA) were also higher (p<0.05) in the blood of goats fed PL especially HPL, compared to the CON. Blood plasma malondialdehyde concentration (mM/mL) of PL treatment groups showed a significant reduction as compared with CON. Supplementation of PL allowed the modulation of rumen characteristics which might represent a feeding strategy to reduce methane emission by directly inhibiting methanogens while improving the health benefits of ruminant products