Effects of Low Protein Diet on Growth Performance,Digestion and Metabolism,Slaughter Performance and Meat Quality of Tan Sheep
The objective of this experiment was to study the effects of low protein diet on the growth perform-ance,digestion and metabolism,slaughter performance and meat quality of Tan sheep.Thirty-six healthy 3-month-old Tan sheep,with similar body condition and average body weight of(21.58±7.94)kg,were selected and randomly split into four groups with three replicates and each replicate with three sheep.Sheep in control group were fed a diet with 13％protein,while those in trial groups Ⅰ,Ⅱ and Ⅲ were fed diets with protein levels that were 1％,2％and 3％lower than that of control group diet based on the energy-nitrogen balance.The pre-feeding period was 10 d and the formal period was 60 d.The results were as follows:1)there were no significant differences in the initial body weight,final body weight and dry matter intake of Tan sheep among the four groups(P＞0.05).The average daily gain of the control group and trial group Ⅰ was significantly higher than that of trial groups Ⅱ and Ⅲ(P＜0.05).The lowest feed to gain ratio was observed in the trial group Ⅰ,which was not significantly different from that of control group(P＞0.05),but significantly lower than that of trial groups Ⅱ andⅢ(P＜0.05).2)There were no significant differences in the apparent digestibility of dry matter,neutral deter-gent fiber and acid detergent fiber of Tan sheep among the four groups(P＞0.05).3)The nitrogen intake of the control group was significantly higher than that of the trial groups Ⅱ and Ⅲ(P＜0.05),and the fecal nitrogen and urine nitrogen were significantly higher than those of the trial groups Ⅰ,Ⅱ and Ⅲ(P＜0.05),but no significant differences in the retention nitrogen,nitrogen digestibility and nitrogen utilization efficiency were observed a-mong four groups(P＞0.05).In contrast,the biological value of nitrogen of the trial groups Ⅰ,Ⅱ and Ⅲ was higher than that of control group,with an increase of 2.13％(P＜0.05),1.54％(P＞0.05)and 0.58％(P＞0.05),respectively.4)Feeding low protein diets had no significant effects on live weight before slaughter,head weight,hoof weight,bone weight and bone/meat ratio(P＞0.05),and had no significant effects on the GR val-ue,loin eye area,tail fat weight and carcass fat weight of Tan sheep(P＞0.05).However,the carcass fat weight decreased correspondingly with the reduction of dietary protein level.The trial group Ⅰ had a 5.12％,10.32％and 4.65％increase in slaughter rate compared with the control group and trial groups Ⅱ and Ⅲ,respectively,but the difference among groups was not significant(P＞0.05).5)Feeding low protein diet had no significant effects on pH45 min,water loss rate,shear force,cooked meat rate,meat color redness and yellowness values,fat color and marbling score of Tan sheep(P＞0.05).The drip loss of the control group was significantly higher than that of the trial group Ⅲ(P＜0.05).The meat color brightness value of trial group Ⅲ was significantly higher than that of control group and trial group Ⅰ(P＜0.05).6)There were no significant differences among the groups in mois-ture,ash and ether extract contents of mutton for Tan sheep(P＞0.05).The crude protein content of mutton for Tan sheep of the control group and the trial group Ⅰ was significantly higher than that of the trial group Ⅲ(P＜0.05).In conclusion,based on the energy-nitrogen balance,dietary protein level is decreased from 13％to 12％,it can not only reduce nitrogen emission,but also have no negative effects on the growth performance,di-gestive and metabolism,slaughter performance and meat quality of Tan sheep.[Chinese Journal of Animal Nu-trition,2024,36(5):3117-3130]
low protein dietTan sheepgrowth performancedigestion and metabolismslaughter perform-ancemeat quality
万方数据
维普
