Study On Energy And Protein Requirements Of 35～60Kg Wei Pig

This research was conducted to investigate the energy and protein requirements of 35⁶0 kg Wei pig（barrows）,which can provide theoretical basis for scientifically feeding Anhui local pig breed-Wei pig.In this paper,feeding experiment,digestion and metabolism test and comparative slaughter test were used to study growth performance,carcass traits,organ development,metabolic rule and requirements of energy and protein for Wei pigs from 35 to 60 kg of live weight during the growing period.We obtained energy and protein requirement factorial model of Wei pig（barrows）growth period（35⁶0 kg）under the experimental conditions.In this study,42 Wei pigs,average weigh（33.47±1.68）kg,were chosen,30 of which were used for comparative slaughter experiment,and the other 12 for digestion-metabolism experiment.In the comparative slaughter experiment,6 Wei pigs were selected randomly to slaughter for estimating initial body composition,and the remaining 24 Wei pigs were divided into three groups--ad libitum group（12 pigs）,70% ad libitum group（6 pigs）and 35% ad libitum group（6 pigs）.When the average weight of 12 Wei pigs in ad libitum group reached 45 kg,6 pigs were chosen from the ad libitum group to slaughter.When the average weight of 6 Wei pigs in ad libitum group reached 60 kg,all the pigs in the three groups were slaughtered.After slaughter,the blood,hair,visceral organs,and the fat of the kidney and the mesenteric fat were collected,respectively.The right side of the head was taken down and the scalp,skulls,muscle and fat of head were separated.The right front hoofs were took down and the bone,muscle,fat and skin were separated.The right side of the carcass bone,muscle,fat and skin were separated.The right side of the carcass,the right side head and the right foot bones,muscles and skin were mixed,respectively.They were bone samples,muscle samples and skin samples.Half of kidney fat,mesenteric fat and the right side of the carcass,head and feet of fat were mixed,which was the composition of fat samples.The pig’s whole blood and guts and intestines were mixed,composing of blood and viscera samples.Six samples were collected from each pig and they are blood + organ,hair,bone,muscle,fat and skin sample.Each sample was sampled about 500 g.Dry matter content of tissue samples（bone,muscle,fat and skin）were measured by freeze-drying method,air-dried samples were made to measure their energy,protein,fat and ash content,thus to estimate the nutrient content of the whole pigs.In the digestion-metabolism experiment,12 Wei pigs,average weight（45.81±1.02）kg,were randomly divided into three treatments and each treatment has 4pigs.Experimental diets and feeding levels were the same as the comparative slaughter experiment.Total faces collection method was used to collect faces and urine.The results showed when the digestible energy level was 12.77 MJ/kg and crude protein content was 14%,the average daily gain（ADG）was 609.47 g,which can meet the experimental design and 35% feeding level can also meet requirement for maintenance.With the decrease of feeding level,F/G showed a rising trend,in addition,F/G in 35% ad libitum group was significantly higher than the other groups（P<0.05）.With the decrease of feeding level,the dressing percentage decreased gradually,and the dressing percentage of 35% ad libitum group was lower than that of ad libitum group.However,with the decrease of feeding level,the rate of bone,muscle and skin increased.There was a significant difference of the rate of bone among groups（P<0.05）;the rate of muscle of ad libitum group was significant lower than those of the others,but the rate of muscle of ad libitum group was significant higher;the rate of skin of 35% ad libitum group was significant lower than those of the others.Feeding levels had no significant effect on organ indexes of stomach,heart,liver,lungs,spleen and kidneys（P>0.05）,but the organ index of liver decreased with the decrease of feeding level.The organ index of liver of 35% ad libitum group was significantly lower than that of ad libitum group（P<0.05）.Feed restriction had no significant effect on apparent digestion rate of DM,OM and N,and energy balance indexes（P>0.05）.A certain degree of feed restriction had no significant effect on net protein utilization（P>0.05）,but if feeding level is too low,net protein utilization would decrease（P<0.05）.The requirement of net energy for maintenance（NE_m）of35⁶0kg Wei pig（barrow）was 344.35 k J/EBW0.75/d and the requirement of metabolizable energy for maintenance（ME_m）was 451.76 k J/EBW0.75/d.The partial efficiency of ME utilization for maintenance（km）were 0.762.The net energy requirements for growth ranged from 5.53 to 18.83 MJ/d and the metabolic energy requirements for growth was 9.72 to 32.22 MJ/d,respectively,for daily gains of300⁷00 g.The partial efficiency of ME utilization for growth（kg）was 0.569.The net protein requirement for maintenance was 0.725 g/EBW0.75/d,Net protein requirement for growth ranged from 41.01 to 94.76 g/d for daily gains of 300⁷00 g.The requirement of crude protein from dietary was 136.16³14.14 g/d.The net energy,metabolizable energy,and net protein requirement of Wei pig（35⁶0 kg）can be estimated by the factorial models as follows:（1）The net energy requirement（NER）factorial model as follows:NER=NE_m+NEg=344.35×EBW₁^0.75+10^[0.147+1.169×Log10（EBW2）]-10^[0.147+1.169×Log10（EBW₁）]（2）The metabolic energy requirement（MER）factorial model as follows:MER=ME_m+ME_g=ME_m+NEg/kg=451.76×EBW₁^0.75+10^[0.147+1.169×Log10（EBW2）]-10^[0.147+1.169×Log10（EBW₁）]/0.569（3）The net protein requirement（NPR）factorial model as follows:NPR= NP_m+NP_g=0.725×EBW₁^0.75+10^[2.340+0.915×Log10（EBW2）]-10^[2.340+0.915×Log10（EBW₁）]Note: In the formula: NER — the total net energy requirement（k J/d）;NE_m — net energy for maintenance（k J/EBW0.75/d）;NEg — net energy for growth（k J/d）;EBW — empty body weight（kg）,body weight before slaughter minus gastrointestinal contents;EBW₁ —initial empty body weight（kg）;EBW2 — the value of initial empty body weight plus daily gain（kg）;MER — metabolizable energy requirement（k J/d）;ME_m—metabolic energy for maintenance（k J/EBW0.75/d）;ME_g—metabolic energy for growth（k J/d）;kg—utilization efficiency of metabolic energy for growth;NPR—net protein requirement（g/d）;NP_m—net protein for maintenance（g/EBW0.75/d）;NP_g—net protein for growth（g/d）.