Effects Of Sweet Sorghum Forage Grass And Grape Seed On Nutrient Utilization,Rumen Microflora And Meat Quality Of Mutton Sheep

With the improvement of people's living standards,the market demand for mutton products is increasing,and the shortage of high-quality forage grass has become a bottleneck restricting the development of China's mutton sheep industry.Sweet sorghum has the characteristics of drought tolerance,waterlogging,salt and alkali resistance,is a high-energy crop,which is suitable for planting in the northwest arid region.It is a new type of forage resource.Grape seed,as a by-product of wine fermentation,has high antioxidant capacity and can improve the production performance of livestock and the quality of livestock products.In this study,the fermentation characteristics of sweet sorghum silage,sweet sorghum hay and grape seed in rumen of Small-tailed Han sheep were evaluated by in vitro method.Secondly,combined with animal feeding experiments,the effects of sweet sorghum forage and grape seed addition on the feeding performance,nutrient utilization,microbial diversity,health indicators and meat quality of Small-tailed Han sheep were explored.Thus,to provide theoretical basis and guidance for developing new forage resources,recycling use local agricultural and sideline products and scientific fattening of mutton sheep.The main findings are as follows:?1?The rumen fermentation characteristics of mutton sheep after 48 hours of different forages were compared in vitro:Fermentation fluid pH was alfalfa silage=grape seed?6.98?>sweet sorghum hay?6.86?>sweet sorghum silage?6.64??P<0.05?,dry matter degradation rate?DMD?was sweet sorghum silage?80.95%?>sweet sorghum hay?70.98%?>alfalfa silage?63.10%?>grape seed?41.88%??P<0.05?,gas production was sweet sorghum silage?275 mL?>sweet sorghum hay?238 mL?>alfalfa silage?126 mL?>grape seed?58 mL??P<0.05?.?2?Effects of sweet sorghum forage and grape seed addition on nutrient utilization and rumen fermentation characteristics of sheep:The sweet sorghum forage and grape seed addition had no significant effect on the apparent digestibility,N retention rate,rumen microbial protein production and rumen fluid concentration of ammonium nitrogen?NH₃-N?of mutton sheep?P>0.05?.The pH of rumen fluid of mutton sheep in sweet sorghum silage group was significantly lower than that in sweet sorghum hay group?P<0.05?,and the concentrations of the concentration of acetic acid,propionic acid,butyric acid and T-VFA in rumen fluid was significantly higher than the sweet sorghum hay group?P<0.05?.The pH of rumen fluid of mutton sheep in grape seed addition group was significantly lower than that the grape seed no addition group?P<0.05?,the concentration of acetic acid,propionic acid,butyric acid and T-VFA in rumen fluid were significantly higher than the grape seed no addition group?P<0.01?.The sweet sorghum forage and addition of grape seed had no significant effect on the rumen microbial abundance and diversity of mutton sheep?P>0.05?.The dominant bacteria in each treatment group were Bacteroidetes,Firmicutes and Verrucomicrobia,which accounted for 50.13%,38.46%and 3.70%of the total bacteria,respectively.At the phylum level,the addition of grape seed significantly increased the relative abundance of Bacteroidetes?P<0.01?,significantly decreasing the relative abundance of Firmicutes?P<0.05?.At the genera level,the addition of grape seed significantly increased the relative abundance of Prevotella₁?P<0.05?.?3?Effects of sweet sorghum forage and grape seed addition on growth performance and slaughter performance of mutton sheep:The dry matter intake?DMI?and carcass weight of the mutton sheep in the sweet sorghum silage group were significantly higher than those in the sweet sorghum hay group?P<0.05?.Sweet sorghum forage and grape seed addition had no significant effect on the average daily gain?ADG?,feed conversion ratio?F/G?,slaughter weight,and slaughter rate of mutton sheep?P>0.05?,however,compared with those fed only with sweet sorghum hay,sweet sorghum silage and grape seed combined feeding increased the final body weight of the mutton sheep by 15.4%,and the average daily weight by more than 30%.The number of red blood cells?RBC?and hematocrit?HCT?in the sweet sorghum silage group were significantly higher than those in the sweet sorghum hay group?P<0.05?,and the mean erythrocyte hemoglobin content?MCH?and mean erythrocyte hemoglobin concentration?MCHC?were significantly lower than those of sweet sorghum hay group?P<0.01?,the platelet count?PLT?was significantly lower than the sweet sorghum hay group on the 50th and 100th day of the test?P<0.05?.The weight of gastrointestinal tract and peri-renal fat in sweet sorghum silage group was significantly higher than that in sweet sorghum hay group?P<0.05?.?4?Effects of sweet sorghum forage and grape seed addition on meat quality and performance:In the sweet sorghum silage group,the longest muscle marble pattern of the mutton sheep was significantly higher than that of the sweet sorghum hay group?P<0.05?,and the dry matter content in the muscle was significantly lower than that in the sweet sorghum hay group?P<0.05?.The color of a*and b*of mutton sheep meat on the grape seed addition group were significantly higher than those of the grape seed no addition group?P<0.05?.The were sweet sorghum forage and grape seed addition had significant interactions effect on C14:0,C14:1,C17:1,C18:1,C20:0,and MUFA in meat fatty acid content?P<0.05?,the effect of grape seed addition on fatty acid content in mutton sheep was not significant?P>0.05?,the sweet sorghum silage group C15:0,C20:0,C18:3 and C22:0 were significantly lower than the sweet sorghum hay group?P<0.05?,sweet sorghum silage group C18:2n-6,C20:3n-6,C20:4n-6,C23:0,C24:0,C22:6n3and PUFA were significantly lower than the sweet sorghum hay group?P<0.01?.In summary,compared with the sweet sorghum hay group,the silage group had higher feed intake,rumen VFA yield and sputum weight,the hay group had higher unsaturated fatty acid content,grape seed addition could change the rumen microflora of and increase the production of volatile fatty acids in the rumen of mutton sheep.Therefore,sweet sorghum can be used as a kind of high-quality roughage in mutton sheep feding.The production performance of silage feeding is significantly better than that of hay.The quality of meat products fed by hay is better than that of silage.If sweet sorghum silage is combined with grape seed addition,mutton sheep production performance is optimal.