关键词: 粗饲料来源, 育肥湖羊, 生产性能, 养分消化, 瘤胃微生物

Abstract: The objective of this study was to evaluate the effects of four different dietary roughage sources on apparent feed dry matter digestibility, animal body weight gain, and rumen microflora when finishing Hu lambs. A total of one hundred and twenty male Hu lambs (22.9±1.2 kg), aged 60 days, were randomly allocated to 4 treatment groups (each comprising 5 replicates of 6 lambs) of similar average weight and weight range. Each of the 4 treatment groups received one of 4 dietary roughage sources: corn stalk (CS), corn cob (CC), sunflower seed hull (SH) or rapeseed straw (RS). For all 4 groups, the dietary proportion of roughage was 20%, and the concentrate component of the diet was the same. A dietary adjustment period of 7 d occurred prior to the experiment, followed by a formal test period of 70 d. At 49-55 d of the formal test, 5 lambs were selected from each group (1 per replicate) to determine the apparent digestibility of feed dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), acid detergent fiber (ADF) and nitrogen (N). At the end of the experiment, 15 lambs were selected from each group for slaughter, collection of rumen contents, rumen microbial DNA extraction, and quantification of rumen bacteria species. It was found that: 1) the dry matter intake (DMI) of Hu lambs in the CS group was significantly higher than in the other three groups (P<0.05). The final body weights and the average daily weight gains for the CS group were significantly higher than those of the RS group (P<0.05), but differences among other groups were not significant (P>0.05). 2) The digestibility values of DM and ADF in the CS and CC groups were significantly higher than those in the RS group (P<0.05), while digestibility values of OM and NDF were significantly higher than those of both SH and RS groups (P<0.05). The digestibility of N in the SH group was significantly higher than that in RS group (P<0.05), while ADF digestibility did not differ significantly between groups (P>0.05). 3) The numbers of Ruminococcus albus and Prevotella brevis in rumen fluid of CS and CC groups were significantly higher than for the RS group (P<0.05), while the numbers of those two bacterial species in the SH group were intermediate, and not significantly different from the other groups (P>0.05). The numbers of Ruminococcus flavefaciens and Fibrobacter succinogenes in CS and CC groups were significantly higher than in the SH and RS groups (P<0.05). There was no significant differences among the 4 groups for numbers of Selenomonas ruminantium (P>0.05). These results indicate that, compared with the sunflower seed hull and rapeseed straw diets, corn stalk diet and corn cob diet are more beneficial to the performance Hu lambs, when finishing for slaughter. and were also beneficial for increasing the number of cellulolytic bacteria in rumen fluid, this also promoting cellulose degradation in the rumen.

Key words: forage source, finishing Hu lamb, growth performance, nutrient digestion, ruminal bacteria