放牧与舍饲模式对滩羊肉品质、瘤胃环境及菌群结构的影响.

[Objective] The paper was conducted to study the effects of grazing and house feeding modes on meat quality and rumen microbiota of Tan sheep. [Method] Thirty-two male lambs ofYanchi Tan sheep with body condition close to[ (20.20 ±2.10) kg]were randomly divided into two groups (group C with total mixed diet) and grazing group (group G with grazing grassland), with 16 lambs in each group. At the same time, fresh rumen fluid was collected for high-throughput sequencing. The effects of grazing and house feeding on rumen microbial diversity and microflora structure of Tanyang sheep were analyzed. The pre-test lasted for 7 days and the test lasted for 80 days. [Result] The intramuscular fat, cooked meat percentage, pH (45 minutes), muscle color L and meat color b of longissimus dorsum of housed Tan sheep were significantly higher than those of grazed Tan sheep (P<0.05), while the pH (24 hours) and meat color a of grazed mutton were significantly higher than those of grazed Tan sheep (P<0.05) . Rumen fermentation parameters analysis showed that rumen pH, isobutyric acid, isovaleric acid and acetic acid/propionic acid of grazing Tan sheep were significantly higher than those of housed Tan sheep (P<0.05), but there were no significant differences in ammonia nitrogen, acetic acid, propionic acid, butyric acid and valeric acid between the two groups (P > 0.05). A total of 2106 OTUs were detected in the two groups, including 1869 and 1445 in the grazing group and the house feeding group, and 661 and 237 unique OTUs, accounting for 31. 38% and 11. 25% of the total OTUs, respectively. The number of species, Shannon index, Chaol index and ACE index observed in rumen microflora of grazing group were significantly higher than those of feeding group (P<0.05), while Simpson index of the two groups had no significant difference (P > 0.05) . The dominant bacteria in the rumen of the two groups were mainly Bacteroidetes, Firmicutesand and Proteobacteria, The relative abundance of Bacteroides in fattening Tan sheep samples was 81. 38%, higher than that in grazing group 52. 96% (P<0.05), while the relative abundance of Firmiculte in fattening group was 15. 88 %, lower than that in grazing group 37. 42 % (P<0.05) . The relative abundance of Proteobacteria in the feeding-house group was 1. 14%, which was slightly lower than that in the grazing group 5. 56% (P<0.05). At the genus level, The dominant genera were mainly unidentified Prevocidae (unidentified_Prevotellaceae), unidentified Bacteroides (unidentified_Bacteroidales), and unidentified Rumen (unidentified_Ruminococcaceae), the proportion of unidentified Prevotella was the highest, and the relative abundance of grazing group was 14. 74%, which was higher than that of fattening group 4. 35 % (P<0.05). The relative abundance of unidentified bacteroides in the grazing group was 3. 63%, which was slightly higher than that in the house feeding group 3. 32% (P > 0.05). The relative abundance of unidentified rumen bacteria in the grazing group was 6. 49%, which was higher than that in the house feeding group 2. 11 % (P<0.05). [ Conclusion] Feeding style can affect meat quality and rumen environment of Tan sheep, in which house feeding is beneficial to fat deposition and improve lamb tenderness, while grazing can improve rumen microbiota diversity and rumen health. [ABSTRACT FROM AUTHOR]