Effects of different amylose to amylopectin ratios on rumen fermentation and development in fattening lambs.

OBJECTIVE: The objective of this experiment was to examine the effects of different amylose/amylopectin ratios on rumen fermentation and development of fattening lambs.

METHODS: Forty-eight 7-day-old male Small-tailed Han sheep×Northeast fine wool sheep were randomly assigned to four treatments of dietary amylose/amylopectin ratios (0.12, 0.23, 0.24, and 0.48 in tapioca starch, corn starch, wheat starch and pea starch diets, respectively). Three lambs from each treatment were slaughtered at 21, 35, 56, and 77 days of age to determine the rumen fermentation and development.

RESULTS: Compared with tapioca starch diet, the pea starch diet significantly increased the concentration of ammonia nitrogen in the ruminal fluid of lambs but significantly decreased the bacterial protein content. At 56 and 77 d, the rumen propionate concentration tended to be greatest in the tapioca starch group than in other groups. The rumen butyrate concentration was the greatest in lambs fed on pea starch compared with those fed on other starch diets. Furthermore, the pea starch diet significantly stimulated rumen development by increasing the papillae height, width and surface area in the rumen ventral or dorsal locations in lambs. However, different amylose/amylopectin ratios diets did not significantly affect the feed intake, body weight, average daily gain, the relative weight and capacity of the rumen in lambs with increasing length of trial periods.

CONCLUSION: Lambs early supplemented with a high amylose/amylopectin ratio diet had favourable morphological development of rumen epithelium, which was not conducive to bacterial protein synthesis.