Performance, rumen fermentation, and gastrointestinal microflora of lambs fed pelleted or unpelleted total mixed ration

The objectives of this study were to evaluate the effects of feeding pelleted total mixed ration (PTMR) on growth performance, ruminal fermentation characteristics, and gastrointestinal microflora of fattening lambs. A total of 100 crossbred (Dorper sheep x Small-tail Han Sheep, DH) ram lambs at 120 d age with similar body weight (BW, 34.9 +/- 0.5 kg) were randomly allocated to 10 pens. The pens were randomly assigned to 2 treatments with 5 replicates per treatment. Dietary treatments were PTMR and un-pelleted total mixed ration (UPTMR) with the same dietary ingredients and nutritional contents. The average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR) were determined in a 32-d experimental period. Ruminal pH, volatile fatty acid (VFA) concentrations, microbes in the rumen and cecum, and carcass weight were measured at the end of the experiment. Lambs fed PTMR had a greater ADFI (P = 0.002) than these fed UPTMR, greater ADG (P = 0.003) and carcass yield (P = 0.003) than that fed UPTMR. However, no significant difference was observed on FCR (P = 0.259) between the two groups of lambs. Compared with UPTMR treatment, feeding PTMR increased acetate and propionate concentrations, while decreased acetate to propionate ratio in the rumen (P < 0.05). Feeding PTMR increased the relative abundance of Prevotellaceae (P < 0.05) and decreased the relative abundance of Rtuninococcaceae (P < 0.05) in the rumen, and increased the relative abundance of Bacwroidales (P < 0.05) and decreased the relative abundance of Lachnospiraceae, Clostridiales and Erysipelotrichales (P < 0.05) in the cecum relative to that of UPTMR group. In conclusion, feeding PTMR improved the growth performance and carcass yield of fattening lamb, primarily due to improvements in ADFI and ruminal fermentation characteristics through changing the structure and abundance of ruminal beneficial microbiota in fattening lambs. Thus, it is a feasible strategy to feed PTMR to fattening lambs in the intensive feed-lot style feeding system.