Effects of dietary roughage sources on the rumen microflora and muscle fatty acids in finishing Hu lambs

The objective of the present study was to evaluate the effects of dietary roughage sources on the rumen microflora and muscle fatty acids in finishing Hu lambs. According to the principle of similar weight, 120 male Hu lambs (22.9 ± 1.2 kg) of age 60 days were randomly divided into four groups (each comprising of five fences of six lambs). Four dietary roughage sources of corn stalk (CS), corn cob (CC), sunflower seed hull (SH) and rapeseed straw (RS) were fed to the four groups. For all the four groups, the proportion of roughage was 20%, and the ingredient concentration was the same. The period of the pre-test was seven days, while the period of the formal test was 70 days. At the end of the trial period, from each fence, three sheep of average weight were selected for slaughter. The rumen fermentation, rumen flora structure, and muscle fatty acid-related indicators were determined. The results showed that: 1) the ratio of valerate and isovalerate in the rumen of the SH and RS groups was significantly higher than that of the CS and CC groups (P < 0.05). The proportion of acetate in the CC group was significantly higher than that in the CS and the RS groups (P < 0.05). 2) The abundance and diversity of the rumen bacterial community in the RS group were the highest, and the similarity of the rumen flora among each group was low. Firmicutes, Bacteroidetes, Spirochaetaes, and Fibrobacteres were the dominant bacteria in the rumen of all the four groups of sheep. The relative abundance of Firmicutes in the RS group was significantly higher than that in the CC group (P < 0.05). The relative abundance of the Spirochaetae in the CC group was significantly higher than that in the SH and RS groups (P < 0.05). The relative abundance of Fibrobacteres in the RS group was significantly lower than the other three groups (P < 0.05). 3) The content of polyunsaturated fatty acids in the SH group was significantly higher than that in the CS group (P < 0.05), and the difference between the other groups was not significant (P > 0.05). The results showed that corn cob diet changes the rumen fermentation process of lambs and increases the proportion of acetate in the rumen. This is beneficial for the proliferation of cellulolytic bacteria and is also suitable as a source of roughage for Hu sheep.