Study On The Effect Of Active Dry Yeast Supplementation On Meat Quality Control Of Yanbian Cattle

Active dry yeast(ADY)has been widely used in ruminants to favorably modify the ruminal environment and improve production performance,but research on its effects on carcass traits and meat quality in beef cattle is limited.The purpose of this study was to explore the effects of ADY on growth performance,slaughter performance,blood related indexes,meat quality related indexes,rumen fermentation and rumen microflora diversity of Yanbian cattle,in order to further clarify the mechanism of ADY affecting beef cattle growth and improving beef tenderness,and to provide theoretical basis for its application and development in beef production in the future.Experiment 1: To explore the effects of ADY on growth performance,nutrient digestibility and blood hormone indexes of Yanbian cattle.This study used a singlefactorial completely randomized design,twenty Yanbian cattle(mean body weight485±38.48kg)with good health status and similar body weight were selected,and they were randomly divided into control group(CON)and experimental group(ADY),with10 heads in each group.The total mixed ration(TMR)feeding mode was adopted in all periods.The beef cattle in the control group were fed with the basal diet,and the beef cattle in the experimental group were fed with the basal diet + ADY,and the addition level was 1 g/head/day.The results showed that:(1)Growth performance: compared with the control group,the DMI of the ADY group was significantly increased(P<0.05),but there was no significant difference in other growth performance indicators(P>0.05).(2)Apparent digestibility of conventional nutrients: compared with the control group,the apparent digestibility of CP in the ADY group was significantly increased(P<0.05),and the apparent digestibility of NDF tended to increase(P=0.096).(3)Apparent digestibility of trace mineral elements: compared with the control group,the apparent digestibility of Zn in the ADY group was significantly increased(P<0.05).(4)Bloodrelated indexes: compared with the control group,The level of acylated Ghrelin in serum of ADY group showed an increasing trend(P=0.053),the level of GOAT was significantly increased(P<0.05),the concentration of CRH was significantly decreased(P<0.05),but other indexes had no significant difference(P>0.05).The above results showed that the ADY supplementation improved growth performance and apparent digestibility of Yanbian cattle to a certain extent,which could significantly increase the feed intake and the apparent digestibility of CP and Zn in Yanbian cattle.The regulation of acylated ghrelin,GOAT and CRH may be the reason for the increase of feed intake.Experiment 2: To explore the effects of ADY on the slaughter performance and meat quality of Yanbian cattle.The experimental design and experimental animals were the same as Experiment 1.By measuring the slaughter performance and meat samples of Yanbian cattle,the results showed that:(1)Slaughter performance: compared with the control group,the marbling score of the ADY group was significantly increased(P<0.05),but other slaughtering performance indicators had no significant difference(P>0.05).(2)Meat quality indicators: compared with the control group,the shearing force in the ADY group was significantly decreased(P<0.05);(3)The conventional chemical composition indicators of beef: compared with the control group,the calcium content in the ADY group was significantly increased(P<0.05),fat content tended to increase(P=0.067).(4)Beef traces mineral elements: compared with the control group,the content of Fe in beef of the ADY group was significantly decreased(P<0.05),and the content of Zn was decreased by 16.35%(P=0.099),but other indicators had no significant difference(P>0.05).In conclusion,the ADY supplementation could regulate the utilization of fat,affect the content of trace mineral elements in beef,and improve beef tenderness of Yanbian cattle.Experiment 3: To explore the effects of ADY on muscle fiber morphology,beef collagen,matrix metalloproteinases and gastrointestinal medium-chain fatty acids in Yanbian cattle.The experimental design and experimental animals are the same as Experiment 1.The results showed that:(1)Muscle fiber morphology: compared with the control group,the muscle fiber density in the ADY group showed an increasing trend(P=0.067),and the muscle fiber diameter showed a decreasing trend(P=0.071).(2)Matrix metalloproteinase(MMP)levels: compared with the control group,the levels of MMP2,MMP9 and MMP13 in the serum and the levels of MMP2 in beef of the ADY group were significantly increased(P<0.05).(3)Collagen content: compared with the control group,the solubility of collagen(proportion of soluble collagen)in ADY group was significantly increased(P<0.05).(4)Medium chain fatty acids content:the content of lauric acid in rumen fluid in ADY group was higher than that in control group,but there was no significant difference in statistics(P>0.05).Capric acid and lauric acid were detected in duodenal chyme,and the content of lauric acid in ADY group was significantly increased(P<0.05).In conclusion,the ADY supplementation could increase the content of MCFA in the gastrointestinal tract of Yanbian cattle,regulate the level of acylated ghrelin in beef cattle,as well as the content of MMPs in serum and meat,increase the proportion of soluble collagen in beef,and improve muscle fiber morphology and meat tenderness.Experiment 4: To explore the effect of ADY on the rumen fermentation and bacterial diversity of Yanbian cattle.The experimental design and the experimental animals are the same as Experiment 1.The following results were obtained by the determination of fermentation indicators and the analysis of bacterial flora diversity in the rumen fluid collected from Yanbian cattle:(1)Rumen fermentation parameters:Compared with the CON group,the proportion of propionate in the ADY group was significantly increased(P<0.05),The ratio of acetate to propionate was significantly decreased(P<0.05),but other rumen fermentation indicators had no significant difference(P>0.05).(2)In terms of rumen microflora diversity,compared with the control group,the Alpha diversity indices ACE,Chao1,Shannon and Simpson had no significant difference in ADY group(P>0.05).(3)In terms of the distribution of rumen microflora,at the phylum level,the relative abundances of Firmicutes and Bacteroidetes in the two treatment groups were dominant;at the genus level,the main genus of the two treatment groups were Succiniclasticum and Christensenellaceae＿R-7＿group,followed by Rikenellaceae＿RC9＿gut＿group,Ruminococcaceae＿NK4A214＿group,uncultured＿bacterium＿o＿Mollicutes＿RF39,Ruminococcaceae＿UCG-014,Prevotella＿1,uncultured＿bacterium＿f＿Muribaculaceae,Butyrivibrio and Ruminococcus.By Metastats analysis of bacterial phylum and genus in rumen fluid greater than 0.1%,Actinobacteria,Christensenellaceae＿R-7＿group and Mogibacterium in the ADY group were significantly lower than those in the control group(P<0.05),among them,Christensenellaceae＿R-7＿group was significantly negatively correlated with lauric acid in duodenal digesta(P<0.05).The above results showed that under the conditions of this experiment,the ADY supplementation could stabilize the internal environment of rumen fermentation of Yanbian cattle,promote the transformation of rumen fermentation into propionic acid fermentation,and affect the rumen microflora structure.ADY may affect the lipid metabolism of Yanbian cattle by regulating the rumen microflora Christensenellaceae＿R-7＿group,thereby increasing the content of MCFA in the gastrointestinal tract and improving meat quality.