| Abstract: | A total of 480 nursery pigs(Duroc×Landrace×Large White) were utilized in two experiments conducted to determine the effects of different ratios of standardized ileal digestible lysine(SIDLys)to metabolizable energy(ME)ratio on the performance,nutrient digestibility,plasma urea nitrogen (PUN),and plasma free anlino acids of 10 to 28 kg pigs.In Exp.1,192 pigs(10.58 kg)were assigned to one of four treatments.,The treaunents consisted of diets with a ME content of 3.2,3.25,3.3,or 3.35 McaL/kg with a constant SID-Lys:ME ratio of 3.7 g/Meal.The experiment lasted 28 days.Pigs which were fed the diets containing 3.3 and 3.35 Mcal/kg ME had lower feed intakes(P<0.05)than those fed 3.2 Mcal/kg.Feed efficiency was linearly improved with increasing dietary ME(P<0.05).Increasing the dietary ME level also increased (P<0.05)dry matter and energy digestibility.Therefore.3.3 Mcal/kg ME Was selected for Exp.2in which 288 pigs(10.60 kg)were assigned to one of six treatments.Treatments consisted of SID-Lys:ME ratios of 3.1,3.3,3.5,3.7,3.9,or 4.1 g/Meal witIl all diets providing 3.3 Meal of ME/kg.Weight gain and feed efficiency were increased(P<0.05)as the SID-Lys:ME ratio in diet increased.Based on a straight broken-line model,the estimated SID-Lys:ME ratio to maximize weight gain was 3.74. |
