Effects of Papain or Bromelain Administration on Rumen Fermentation, Blood Metabolites, and Meat Quality in Sheep

Papain and bromelain are plant-derived proteolytic enzymes that may enhance protein degradation and nutrient availability in livestock.This study aimed to evaluate the effects of oral administration of papain or bromelain on rumen fermentation characteristics, blood metabolite profiles, and meat quality of thin-tailed sheep.Fifteen female thin-tailed sheep (8-10 months old; body weight 12.75 ± 0.30 kg) were randomly assigned to three groups (n = 5 per group): a control group, a papain-treated group (36 mg/kg body weight), and a bromelain-treated group (36 mg/ kg body weight), with treatments administered orally.Sheep were fed a diet consisting of 70% starter concentrate and 30% Pennisetum purpureum for 12 weeks.The parameters measured included rumen fermentation characteristics, blood metabolites profile, feedlot performance, and meat quality.Oral administration of papain or bromelain tended to reduce nutrient intake (P < 0.10) and increase the molar proportion of propionate (P = 0.08).In addition, bromelain administration tended to increase blood albumin concentration compared with the control (P = 0.06).No differences were observed in average daily gain, final body weight, and carcass traits by papain or bromelain oral administration.The administration of papain significantly increased (P