Effects of low protein diet on growth performance,meat quality and economic benefit of mutton sheep
This experiment was conducted to investigate the effects of low protein diet on growth performance,meat quality and economic benefit of mutton sheep.A total of 160 Duhan mutton sheep with an average weight of(32.87±1.24)kg at the age of 4 months were divided into 4 groups,with 1 group per 5 replicates and 1 replicate per 8 sheep.Crude protein decreased by 0%,1%,2% and 3% on the basis of the basal diet were the diets of trial groups Ⅰ,Ⅱ,Ⅲ and Ⅳ for 90 days,7 days of pre-feeding,and 83 days of trial.The results showed as follows:FBW in 3% crude protein group was significantly decreased by 5.53% compared with control group(P＜0.05);Compared with the control group,the total weight gain and ADG in the 2% and 3% crude protein groups were significantly decreased by 9.39% and 18.89%,respectively(P＜0.05).F/G of meat sheep in 3% lower crude protein level group was significantly decreased by 24.77% compared with control group(P＜0.05);In addition,dietary crude protein level had no significant effect on DMI of mutton sheep(P＞0.05).The L value and b value of longissimus dorsi muscle of meat sheep in 2% and 3% lower crude protein levels were significantly increased(P＜0.05);The a value of longissimus dorsi muscle of mutton sheep in 2% and 3% crude protein groups was significantly decreased(P＜0.05);The thawing and cooking loss of longissimus dorsi muscle in 2% and 3% lower crude protein levels were significantly increased(P＜0.05);The shear force of longissimus dorsi muscle of meat sheep in 2% and 3% crude protein groups was significantly increased(P＜0.05);In addition,dietary protein level had no significant effects on pH and water power of longissimus dorsi muscle at 45 min and 24 h(P＞0.05).The unit prices of diets in groups Ⅰ to Ⅳ were 2.14,2.06,2.01 and 1.96 yuan/kg,respectively.The feed costs of groupsⅠ to Ⅳ were calculated to be 294.85,288.96,278.61 and 273.30 yuan per head.The price of live meat sheep is 24.72 yuan/kg,so the gross profit of group Ⅰ to Ⅳ of the comprehensive calculation test is 163.21,155.02,136.44 and 98.24 yuan,respectively.In conclusion,the protein level has a great effect on the growth and meat quality of meat sheep,and reducing the crude protein level by 1% has no significant negative effect on the growth of meat sheep.
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