Study On Energy And Protein Requirements Of 20~35kg Chuanzhong Black Goat

This study was conducted to determine the energy and protein requirements of Chuanzhong black goat male lamb?BW ranged from 20 to 35 kg?,aiming to provide data reference for the improvement of raising standards of goat in China.In the study,a total of twenty-two 2.5-month-old Chuanzhong black goat male lambs?BW=19.97±5.47 kg?were selected.Four lambs were used in the initial comparative slaughtering trial,eighteen lambs were used in feeding trial and digestion-metabolism trial.The pre-feeding period was 14 days,and the official trial was 82 days.Animals were divided into 3 treatments:ad libitum feeding group?AL group?,75%ad libitum feeding group?AL75 group?and 60%ad libitum feeding group?AL60 group?.There were 6 replicates per treatment,and 1 lamb per replicate.When the BW of AL treatment reached 35 kg,four lambs per treatment were subjected to a comparative slaughter trial.Based on the results of feeding trial,digestion-metabolism trial,and comparative slaughtering trial,the production performance,slaughter performance,organ development,digestion and metabolism of energy and protein,and requirements of 20-35 kg Chuanzhong black goat male lambs were systematically studied.The energy and protein requirement model of 20-35 kg Chuanzhong black goat male lambs were obtained by this method.Research indicates:?1?Production performance:The dry matter intake of the AL group,AL75group and AL60 group were 912 g/d,706 g/d and 544 g/d,respectively.The feeding level decreased significantly?P<0.01?,and the average daily gain were 157 g,115 g and 58 g,respectively.The difference between the groups was extremely significant?P<0.01?,and the feed to weight ratio were 6.70,7.01,and 12.18,respectively.The AL60 group was significantly higher than the AL group and AL75 group?P<0.05?.?2?Slaughter performance:At the end of the AL group test,the shrunk body weight was 33.28 kg,the slaughter rate was 53.3%,the net meat rate was 41.43%,the carcass net meat rate was 77.16%,and the bone-meat ratio was 0.37.?3?Organ index:The heart organ indexes of AL group,AL75 group and AL60group were 0.43%,0.45%and 0.42%,respectively,the difference was not significant?P>0.05?liver organ indexes were 1.93%respectively,1.79%,1.71%,the AL group was significantly higher than the AL75 group and AL60 group?P<0.01?,the spleen organ index was 0.16%,0.17%,0.15%,the difference was not significant?P>0.05?,the lung organ index Respectively 1.14%,1.40%,1.36%,the difference was not significant?P>0.05?,the kidney organ index was 0.34%,0.31%,0.26%,with the feeding level decreased significantly decreased?P<0.01?,fur organ index They were7.94%,8.66%,and 8.43%,with no significant difference?P>0.05?.Among them,liver and kidney have the greatest influence on organs.?4?Energy and nutrient digestibility:The apparent digestibility of DM,CP,NDF,ADF,energy in the AL group was 72.70%,69.61%,40.08%,33.33%and68.71%,respectively.The net protein utilization rate was 19.77%,the total energy metabolism rate and the digestive energy metabolism rate was 59.20%and 87.28%.?5?Maintenance energy and protein requirements:Maintenance net energy requirement is 178.24 k J/kg·BW^0.75·d,and maintenance metabolic energy requirement is 263.74 k J/kg·BW^0.75·d.The metabolic energy maintenance and utilization efficiency?k_m?is 0.68,and the metabolic energy growth and utilization efficiency?k_g?is 0.3147.The net protein requirement is 1.60 g/kg·BW^0.75·d.?6?Forecast model of energy and protein requirementsThe prediction models for net energy,metabolic energy,and net protein requirements are as follows:The prediction model of the net energy demand?NER?obtained by the factorial method is:NER=NE_m+NE_g,(NE_m=178.24 k J/kg·BW^0.75·d)Log₁₀?ER?=0.429+1.391×log₁₀?EBW?EBW?kg?=-0.1183+0.8697×BW?kg?The predictive model of metabolic energy requirement?MER?obtained by the factorial method is:MER=ME_m+ME_g,(ME_m=263.74 k J/kg·BW^0.75·d,ME_g=NE_g/k_g,k_g=0.3147)log₁₀?ER?=0.429+1.391×log₁₀?EBW?EBW?kg?=-0.1183+0.8697×BW?kg?The prediction model of the net protein requirement?Np R?obtained by the factorial method is:Np R=Np_m+Np_g,(NP_m=1.60 g/kg·BW^0.75·d)log₁₀?NR?=-0.672+1.033×log₁₀?EBW?EBW?kg?=-0.1183+0.8697×BW?kg?...