The Research Of Net Energy Requirement And Appropriate True Digestivelys: Net Energy Ratio In 21-50kg Growing Pigs

Two experiments were designed in this study.The Net Energy of corn and soybean meal were calculated on the basis of actually evaluating the Apparent Digestible Energy(ADE) and Apparent Metabolizable Energy(AME).Then Experiment 2 was conducted to investigate the effects of true digestive Lysine(Lys) and Net Energy(NE) levels on growth performance and N balance in growing pig to research net energy requirement and appropriate true digestive lys:net energy ratio in 21-50kg growing pigs.Experiment 1,A Latin-square-designed trial was taken on 6 castrated male pigs (Duroc×Landrance×Yorkshire,initial body weight:35±1kg) to evaluation the ADE and AME of corn and soybean meal.The ADE and AME of corn were 3993kcal/kgDM,3904 kcal/kgDM.The ADE and AME of soybean meal were 3825 kcal/kgDM,3404 kcal/kgDM.The Net Energy(NE) accorded to prediction formula of corn and soybean meal were 3076 kcal/kgDM,2142 kcal/kgDM.Experiment 2,36 castrated pigs[Yorkshire×Landrace×Duroc]were allotted randomly by gender,litter and weight(average initial body weight of 21.35 kg) to six treatments with six replicates per treatment.Pigs were fed two levels of lys(0.793%, 0.879%) and three levels of NE(2251,2351,2451 kcal/kg) in a 2×3 factorial arrangement. Piglets in each pen were weighed as a group on d 0,7,14,28,and 35.Feed intake was determined weekly.Average Daily Gain(ADG),Average Daily Feed Intake(ADFI) and Feed:Gain ratio(G:F) were calculated per pen.When pigs were about 33kg,4 replicates of per treatment were used to determine the effects of feeding two levels of lys and three levels of NE on pig N balance.The effects of lys(P=0.127)or net energy(P=0.058)on ADG were not significant.A Lys×NE interaction in ADG was observed(P＜0.05).The results indicated that the ADG of lys0.793%-NE2351kcal/kg treatment was the highest(866g/d),which had higher ADG than lys0.793%-NE2251kcal/kg treatment and lys0.879%-NE2451 kcal/kg treatment(P＜0.01).There were no difference in ADFI and G/F(P＞0.05).The effects of lys,net energy,Lys×NE on ADFI and G/F were not significant(P＞0.05).The effects of lys(P=0.069),net energy(P=0.281),Lys×NE(P=0.052) on N retention (percentage) were not significant.The N retention(percentage) of lys0.793%-NE2351 kcal/kg treatment was the highest,which had higher N retention than lys0.879%-NE2351 kcal/kg treatment and lys0.879%-NE2251 kcal/kg treatment(P＜0.01). The effects of lys,net energy on N retention(percentage) were not significant.There was Lys×NE interaction in N ABV(P＞0.05).The N ABV of lys0.793%-NE2351 kcal/kg treatment was the highest,which had higher N ABV than treatment lys0.879%-NE2351 kcal/kg treatment and lys0.879%-NE2251 kcal/kg treatment(P＜0.01).Generally speaking,these results suggest that diets fed to pigs from 20 kg to 50 kg of body weight,whose appropriate net energy level is 2651 kcal/kg(dry matter),appropriate true digestible Lysine per kilogram of feed is 0.922%(dry matter) and appropriate Tdlys/NE is 3.426g/Mcal NE.