Effects Of GAA And RP-Met On Growth Performance,Meat Quality,Glycometabolism Key Enzymes And Rumen Fermentation Of Tan Sheep

Thirty-six Tan lambs with an average body weight of(20.4 ± 1.7)kg were randomly assigned into 3 groups(12pens per group).Those in the control group fed a basal diet,and those in other groups fed the basal diet containing 0.08%GAA and 0.06%RP-Met,0.08%GAA and 0.08%RP-Met,respectively.The per-feeding period lasted for 7 d,and test period lasted for 90 d.The aim of this study was to determine the effects of guanidine acetic acid(GAA)and rumen protected methionine(RP-Met)on growth performance,carcass traits,nutrient apparent digestibility,meat quality,serum biochemical parameters,glycometabolism key enzymes and rumen fermentation of Tan lambs.The results showed that compared with the control group,test group 1 significantly increased the average daily gain and final body weight,significantly decreased the feed to gain ratio(P<0.05).The average daily feed intake of the test group 2 was significantly reduced(P<0.05),but the final body weight and average daily weight gain were not significantly different from those of the control group.Compared with the control group,the slaughtering rate of the experimental group increased,the carcass weight/carcass weight decreased,but the difference were not significant(P>0.05).With the increase of GAA and RP-Met supplementation,the apparent digestibility of dry matter and crude protein in the diet increased significantly(P<0.05).The digestibility of organic matter,crude fat and neutral washing fiber increased in the experimental group,but the difference was not significant compared with the control group(P>0.05).Both abdominal fat/carcass weight and tail fat/carcass weight decreasedand and significantly reduced the GR value in test groups(P<0.05).In terms of muscle nutrients,the content of protein,intramuscular fat and glycogen in test group 2 increased significantly(P<0.05),and the content of intramuscular fat in test group 1 increased significantly(P<0.01).Diets supplemented GAA and RP-Met significantly increased water-holding capacity,the pH 45min and 48h(P<0.05),significantly reduced drip loss and shearing force in muscles.Compared with the control group,the test group 1 significantly increased 24h a*value and b*value,the test group 2 significantly reduced 0h,24h,48h L*value and 0h a*value(P<0.05).The serum total protein,albumin and triglyceride were increased significantly,the blood sugar,urea nitrogen and cholesterol were significantly reduced in serum of Tan sheep(P<0.05).There was significant increased pyruvate kinase,malic dehydrogenase,isocitrate dehydrogenase,ATP synthetase,creatine kinase,nicotinamide adenine dinucleotide coenzyme Q reductase among the treatment groups(P<0.05).And the contents of ammonia nitrogen was significantly decreased in rumen fluid and volatile fatty acids was significantly increased in each treatment group(P<0.05).In summary,dietry supplementation of GAA and RP-Met improved growth performance and slaughter performance,enhanced digestibility of dry matter and crude protein,increased muscle protein,intramuscular fat and glycogen content of Tan lambs.Effectively regulated the fat deposition and obviously improved the quality of Tan lambs.Increased the serum total protein,albumin and reduced the urea nitrogen and cholesterol in serum of Tan sheeps.And GAA and RP-Met increased the content of glycometabolism and respiratory chain key enzymes in Tan lambs.Increased volatile fatty acids and keeped the stability of the circumstance of inner rumen.