| Sheep production is predomoniant industrial in animal husbandry of China,the mutton market is huge and the annual mutton output occupies an important position in the world.In recent years,with the improvement of domestic consumption,consumers pay more attention to the quality of mutton.Intramuscular fat as an important factor in evaluation of meat quality,can directly affect the sensory indicators related to meat quality,such as mutton tenderness,juiciness,flavor and so on.Thus,improving the intramuscular fat content and distribution can improve the meat quality,improve the edible quality of sheep.Betaine can provide methyl for the synthesis of carnitine,creatine and other substancesin the body,it also has effect of adjusting the poultry fat distribution,improving intramuscular fat content of breeding pig to improve the meat marbling score.In order to study the effects of rumen protected betaine on production performance and fat deposition of 3-5 months and 9-10 months Hu lambs and provide the theoretical and basic data for fattening mutton lambs in production.This research mainly includes the following parts:Experiment 1:Effects of rumen protected betaine on growth performance and fat deposition of 3-5 months Hu lambs.A single factor randomized experimental design was applied this research to study the effect of adding rumen protected betaine on growth performance,slaughter performance meat quality and fat deposition of 3-5 months Hu lambs.24 lambs with the similar body weight of 21.74±2.54kg were randomly divided into three groups with 8 lambs per group,which included control,Bet and RPB.Sheep in control were fed with a basal diet,while those in Bet and RPB were fed the the diets with 1.6 g/kg Bet and 2.9 g/kg RPB on the basis of dry matter,respectively.The test had a 7-day for pre-experiment and a 61-day for experiment.Results:1)Bet and RPB had no significant effect on growth performance(P>0.05).2)For the rumen,the pH of RPB was significantly higher than control and Bet(P<0.05),Bet had a tendency to increase the total concentration of VFA(0.05<P<0.10),the acetic acid and ethylene propylene ratio of Bet were significantly higher than control and RPB(P<0.05),and the NH3-N,propionic acid and butyric acid had no difference among groups(P>0.05).3)There was no significant difference between Bet and RPB in blood biochemical indexes and lipid metabolism hormone(P>0.05).4)Bet and RPB had no significant effect on apparent digestibility of various nutrients(P>0.05).5)Bet and RPB could significantly affect the rumen ratio(P<0.01),but had no significant effect on the slaughter performance and other organ indices(P>0.05).6)For longissimus dorsi muscle,adding Bet and RPB significantly reduced the water loss rate,and significantly improved a*(P<0.01).The shear force of RPB was significantly lower than the control and Bet(P<0.05);For the Gluteus muscle,shear stress of RPB significantly lower than Bet(P<0.05).The pH24h of Bet was significantly higher than other groups(P<0.05),while a*of RPB was significantly higher than other groups(P<0.01).According to the meat quality index score,the control had the worst longissimus dorsi muscle,the RPB had the best muscle quality,especially the longissimus dorsi muscle.7)There was no significant effect on the backfat thickness,abdominal fat weight,perirenal fat weight and intramuscular fat content(P>0.05).8)The proportion of C16:0 and C16:1N7 in Bet was significantly lower than that in the other groups(P<0.05),while the proportion of C17:0 was significantly higher than that of the control(P<0.05).The proportion of C20:2 in RPB was significantly lower than that in control(P<0.05),but C20:3N3 was significantly lower than that in Bet(P<0.05).Addition of RPB significantly reduced the proportion of PUFA(P<0.05)and it has a tendency to reduce n-6 PUFA.Compared with Bet,the proportion of n-3 PUFA and PUFA/SFA in RPB decreased significantly(P<0.05).Experiment 2:Effects of rumen protected betaine on growth performance and fat deposition of 9-10 months Hu lambs.A single factor randomized experimental design was used to study the effect of adding rumen protected betaine on growth performance,slaughter performance meat quality and fat deposition of 9-10 months Hu lambs.15 lambs with the similar body weight of 45.91±4.39 kg were randomly divided into three groups with 5 lambs per group,which included control,Bet and RPB.Lambs in control were fed with a basal diet,while those in Bet and RPB were fed the the diets with 1.6 g/kg Bet and 2.9 g/kg RPB on the basis of dry matter,respectively.The test had a 7-day for pre-experiment and a 35-day for experiment.Results:1)Bet and RPB had no significant effect on growth performance(P<0.05).2)The addition of Bet and RPB can significantly increase the proportion of acetic acid(P<0.05),and RPB can significantly increase the proportion of propionic acid(P<0.05),the concentration of ammonia nitrogen,pH.total volatile fatty acid concentration,butyric acid and ethylene propylene ratio of three groups had no significant difference(P>0.05).3)The content of Urea in serum of RPB was significantly higher than that in control group and Bet(P<0.05).Compared with control,Bet and RPB had a tendency to increase the congcentration of CHO(0.05<P<0.10),and the HDL in Bet and RPB was significantly higher than that in control group(P<0.05).However,the effects of ALB,TP,GLU,TG and LDL on blood of Bet and RPB were not significant(P>0.05).4)The addition of Bet and RPB had no significant effect on the digestibility of CP,DM,OM and EE(P>0.05).But the addition of Bet had a tendency to increase the digestibility of NDF and ADF(0.05<P<0.10).5)RPB had a tendency to increase the rate of sheep slaughter(0.05<P<0.10),and RPB can significantly reduce the hind leg weight(P<0.05),Bet and RPB can significantly increase the net weight of the stomach(P<0.05),but Bet and RPB showed no significant effects on the other slaughter performance index and other organ index(P>0.05)6)Compared with control and Bet,RPB had a tendency to increase pH24h of middle gluteal muscle(0.05<P<0.10),but the addition of Bet and RPB on other meat quality had no significant effect(P>0.05).7)The visceral fat percentage in total fat of RPB was significantly higher than Bet(P<0.05),and RPB had a tendency to increase Subcutaneous fat weight(0.05<P<0.10),the backfat thickness,abdominal fat weight,visceral fat weight and other index which reflect fat deposition had no significant effect(P>0.05).8)RPB can significantly increase C16:1N7(P<0.05),but Bet and RPB had no significant effect on the other fatty acids(P>0.05).Conclusion:1)At the age of 3-5 months,Bet and RPB can promote the development of rumen and improve the meat quality,RPB can improve the intramuscular fat content of longissimus dorsi muscle to some extent,Bet can significantly reduce the ratio of abdominal fat/carcass weight.2)At the age of 9-10 months,RPB had a tendency to increase the slaughter rate,Bet and RPB can redistribute the fat distribution in a certain extent and increase the intramuscular fat of longissimus dorsi muscle and total body fat content,but had no significant effect on meat quality.3)In summary,adding RPB to diet of lambs at 3-5 month old was more suitable for regulating meat quality and improving carcass fat distribution,in addition,it is the effective period of fattening Hu lambs by using RPB in production. |
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