Study On The Nutritional Value Of Silage Type Fermented TMR And Its Effects On Fattening Sheep

With the development of high-quality grass grazing,there are various forms of total mixed rations(TMR)for livestock.Fermented total mixed rations(FTMR)is a new type of feed produced by combining silage fermentation with TMR production technology,and has attracted more attention because of its many advantages such as ease of use.In this study,a series of studies on the nutritional quality and feeding effect of FTMR for sheep were conducted in the experimental area based on the resource endowment and production practice,with maize straw silage as the main roughage source and unfermented silage as the control.Twelve thin-tailed Han sheep(25.58±3.36 kg)were divided into 2 groups according to the diets:silage-type TMR(CON)and silage-type FTMR(FTMR).The feeding experiment lasted for 105 days,with a transition period of 15 days and a trial period of 90 days.The results of the study were as follow:1.Compared to CON,FTMR had a lower neutral detergent fiber(NDF)and acid detergent fiber(ADF)content(P<0.001),while the crude protein(CP)content(P=0.002),relative feeding value(RFV,P<0.001)and total digestible nutrients(TDN,P<0.001)were higher than in the unfermented TMR.The results of the Cornell Net Carbohydrate Protein System(CNCPS)evaluation indexes showed that non-protein nitrogen,rapidly and moderately degraded protein and bound protein fractions were unaffected by the fermentation treatment(P>0.05),while the FTMR had a lower neutral insoluble protein content(P=0.004)and a higher soluble protein content(P=0.013)with an increase of 18.92%,and a lower slow degraded protein(P=0.003).The FTMR group had higher proportion of acetate,propionate and lactate(P<0.001)and lower proportion of butyrate(P<0.001),with a 2.6%decrease in p H(P=0.001).2.The dry matter intake(DMI)was lower in the FTMR group compared to the CON group(P=0.012),while feed conversion efficiency was higher(P=0.010).No differences were found in final body weight and daily gain between the two groups(P>0.05).The CP and ADF digestibility were higher in the FTMR group(P<0.001).The ruminal p H,ammonia nitrogen,the proportion of propionate and the ratio of acetate to propionate were similar between the two groups(P>0.05).However,the concentration of total volatile fatty acids(TVFA,P=0.004)and proportion of butyrate(P=0.003)were higher in the CON group than in the FTMR group.In addition,both methane and fecal nitrogen excretion were higher in the CON group than in the FTMR group.3.The FTMR group had a slightly higher live weight before slaughter(42.72 kg vs.40.91 kg),carcass weight(20.47 kg vs.20.01 kg)and backfat thickness(6.33 mm vs.5.84 mm)than the CON group(P>0.05),while the slaughter rate(47.89%vs.48.90%)and eye muscle area(13.55 cm~2 vs.17.17 cm~2)were lower(P>0.05).The proportion of tertiary meat was lower in the FTMR group than in the CON group(P=0.009),while the proportion of primary meat was increased by 13.31%compared to the CON group.There was no difference in moisture,crude protein(CP)and ether extract(EE)in the nutritional fractions of lamb between the two groups(P>0.005).There were no differences in p H,meat color and percentage of cooked meat between the two groups(P>0.005).The contents ofα-linolenic acid(C18:3n3,P=0.033)and linoleic acid(C18:2n6c,P=0.001)were higher in the CON group than in the FTMR group,while the content of trans linoleic acid(C18:2n6t,P=0.011)is higher in the FTMR group.The content of Myristic acid(C14:0,P=0.053)and myristic acid(C14:1n9c,P=0.058)in the CON group was slightly higher than in the FTMR group.In terms of fatty acid nutritional value of lamb,the atherogenic index(0.51 vs.0.52),thrombogenic index(0.54 vs.0.56),Δ6+Δ5 desaturase activity(0.32 vs.0.27)and peroxidability index(4.51 vs.5.38)were better in the FTMR than in the CON.During refrigeration,the degree of lipid oxidation in the CON group was stronger than that in the FTMR group.Comparing the economic benefits of the two groups,the FTMR group had lower costs than the CON group,and the IOFC(Income over feeding cost)increased by28.81%.In summary,compared to unfermented TMR,fermentation significantly reduced the NDF,ADF and slow degrading protein content and increased the CP and fast degrading protein content in the ration,improving the feeding value in terms of nutrient composition and fermentation quality,and significantly improving the feed conversion efficiency and apparent nutrient digestibility of fiber fractions in fattening sheep,with the potential to slow down lipid oxidation in sheep and improve farming efficiency to a certain extent.