Effects Of Dietary Non-Forage Fibre Sources And Starch Levels On Performances And Rumen Function Of Finishing Hu Lamb

The formations and sources of carbohydrate are important nutritional factors,which can control the rumen health and influent the production performances of ruminants.Non-forage fibers such as soybean hulls and beet pulp have the nutritional characteristics of fibrous carbohydrate and that of non-fibrous carbohydrate.Non-forage fibers can replace the starches and roughage sources fibers in ruminant diets.Moreover,Non-forage fibers can maintain the efficient fermentation and health of rumen.In this study,we adjusted the levels of non-forage fiber sources and starches in diets.In this way,we can evaluated how can they influence the growth performances of fattening lambs,epithelial function of rumen,and formation of microflora and muscle fatty acid.Furthermore,we could provide theoretical basis for reasonable levels of starch and non-forage fiber sources to ensure rumen healthy and efficient fermentation.In this experiment,2-month-old weaning Hu lambs were selected 360?BW=24.72±0.14 kg?.The lambs were randomly divided into 6 disposals,with 6 repetitions in each disposal and 10lambs in each replicate.A 2×3 factor's design was adopted.The experimental factors were non-forage fiber sources?beet pulp and soybean hulls?and starch levels?28%,25%,22%?,respectively.The trial period continued 87 days,including a 14 days of transition,10 days of pre-feeding,and 63 days of trial.The average body weights of the lambs were measured at 21d,42d,and 63d,as well as average daily weight gain?ADG?and dry matter intake?DMI?of fattening Hu lambs respectively.After trial,two lambs of each unit was slaughtered to determine the slaughter performances.At the same time,rumen fluid,rumen content,longissimus dorsi,and rumen epithelium were collected to evaluate the function of rumen,as well as the microflora community and muscle fatty acid composition.By experiments,the influences of daily non-forage fiber sources and the levels of starch on growth and fattening performance,rumen function,microflora and muscle fatty acids of Hu lambs could be identified,respectively.The results were present blow:1.The high starch level finishing Hu lamb's 1²1 d ADG was significantly higher than the low starch level?P<0.05?.Each period weights and 42⁶3 d DMI of soybean hulls were significantly higher than those of beet pulp?P<0.05?.Soybean hulls treatment had the higher NDF intake,ADF intake and the digestibility of ADF than beet pulp treatment?P<0.05?.The high starch level had the lower the digestibility of NDF than the low starch groups?P<0.05?.Live weights of soybean hulls treatment were significantly higher than those of beet pulp treatments?P<0.05?.With the increase of starch levels,carcass weights and slaughter rate increased significantly?P<0.05?.2.Increase dietary starch levels,the concentration of acetate in rumen fluid was decreased?P<0.05?,the proportion of propionic acid in rumen fluid was increased?P<0.05?.The proportion of butyric acid was significantly higher in beet pulp treatment than that in soybean hulls treatment?P<0.05?.The luminosity,redness and yellowness of the rumen for beet pulp were significantly higher than those of soybean hulls treatment?P<0.05?.Increase dietary starch levels,the luminosity,red degree and yellowness of the dorsal sac were significantly increased?P<0.05?.The expression of Na⁺/H⁺exchanger 3?NHE3?and 3-hydroxymethyl-3-methylglutaryl-CoA lyase?HMGCL?decreased with the increase of starch levels?P=0.094,P=0.076?.3.The high starch level's number of F.succinogenes was significantly lower than that of the low starch level in beet pulp treatment?P<0.05?.The number of S.bovis decreased with the increase of dietary starch levels?P<0.05?.The total number of bacteria increased with the increase of starch levels?P<0.05?.The number of P.brevis was significantly higher in beet pulp treatment than that in soybean hulls?P<0.05?.The number of R.amylophilus and S.bovis was significantly lower in beet pulp treatment than that in soybean hulls?P<0.05?.4.The Shannon index,Simpson index and Chao1 index were significantly lower in beet pulp treatment than in soybean hulls treatment?P<0.05?.The Shannon index of high starch level was significantly lower than that of low starch level?P<0.05?.The abundance of Bacteroidetes,Fibrobacteres and Proteobacteria were significantly higher in beet pulp treatments than that in soybean hulls treatments?P<0.05?.The abundance of Firmicutes was significantly lower in beet pulp treatment than that in soybean hulls treatment?P<0.05?.The high starch level of Proteobacteria was higher than that of low starch level?P<0.05?.The high starch level of Verrucomicrobia was lower than that of low starch level?P<0.05?.The high starch level of Bacteroidetes and Actinobacteria were a higher trend than those of low starch level?P=0.097,P=0.059?.The abundance of Candidatus_Saccharimonas,Christensenellaceae_R-7,Rumino coccus₁ and Succiniclasticum were significantly lower in the beet pulp treatment than those in soybean hulls treatment?P<0.05?.The abundance of Fibrobacter was significantly higher in the beet pulp treatment than that in soybean hulls treatment?P<0.05?.The high starch level of Butyrivibrio₂ and Lachnospiraceae_NK3A20 were lower than those of low starch level?P<0.05?.The beet pulp and high starch level of Olsenella was a higher trend than that of the beet pulp low starch level?P=0.086?.5.The proportion of C10:0,C12:0,C14:0,C18:1 13t+14t and C18:1 C12 in the muscle in beet pulp treatment were significantly higher than those of soybean hulls?P<0.05?.Beet pulp treatment C15:0 content was significantly lower than soybean hulls treatment?P<0.05?.The proportion of C15:0 iso,C17:0 anteiso,C18:0,C20:2 9c,t11,C18:1 t11 and C18:1 c11 in high starch treatments were significantly lower than those of the low starch treatments?P<0.05?.The proportion of C18:1 c10+15t and C18:1 c12 in high starch groups were significantly higher than those of low starch groups?P<0.05?.In summary,in the early stage of lamb fattening,it could improve the animal's growth performances,and the soybean hulls were higher than the beet pulp in each period's weights of fattening Hu lambs.Raising the starch levels in lamb fattening stage could enhance the slaughter performance.s The reduction of starch levels could improve the rumen function of the sheep,so that the rumen fermentation mode was acetic,the color of the rumen was dark,and the expression of the related genes in the rumen epithelium was enhanced.By using beet pulp,it would increase the abundance of the Fibrobacter in the rumen so as to increase the ratio of C15:0 anteiso.Reducing dietary starch could improve the content of CLA precursor C18:1 t11 and C18:1 c11 in the muscle,while enhancing the hydrogenation of the fibrous decomposition bacteria.However,the increase dietary starch levels would increase the total number of microorganisms in the rumen,but the microbial diversity was reduced.