The effects of supplementing sweet sorghum with grapeseeds on dry matter intake, average daily gain, feed digestibility and rumen parameters and microbiota in lambs

This study examined the effect of supplementing sweet sorghum with grapeseeds on dry matter intake, average daily gain, feed digestibility and rumen parameters and microbiota in small-tailed Han lambs. A total of 28 lambs (19.1 +/- 1.20 kg) were divided randomly into four dietary treatment groups and received alfalfa silage (1% BW on DM basis) and concentrate feed (2% BW on DM basis) plus: 1) sweet sorghum silage (SS); 2) sweet sorghum silage + grapeseeds (SSG); 3) sweet sorghum hay (SH); and 4) sweet sorghum hay + grapeseeds (SHG). Sweet sorghum silage and hay were offered ad libitum and grapeseeds, when offered, were added at 6% DM of concentrate feed, which was equivalent to approximately 2.7 % of total DMI. Grapeseeds did not affect DMI, but DMI of the silage groups were higher than the hay groups (P<0.05) and the ADG of SSG was higher than SH (P<0.05). Grapeseeds had no effect on rumen microbial protein yield, efficiency of microbial protein synthesis and excretion of urine purine derivatives. The SSG group had lower rumen fluid pH and acetate:propionate ratio but higher concentrations of total VFAs, acetate, propionate, butyrate, isovaleric acid and valerate than the other three groups (P<0.05). Supplementary grapeseeds did not affect ruminal bacteria diversity, but increased the relative abundance of Bacteroidetes and Prevotella 1 (P<0.01) and decreased Firmicutes (P<0.05). It was concluded that there was an increase in total VFAs and the relative abundances of ruminal bacteria were altered in lambs when sweet sorghum was supplemented with grapeseeds to the diet.