The interaction between threonine and avilamycin on piglet performance and diet digestibility post weaning

A 3 × 2 factorial experimental design was used to investigate the interaction between threonine level (8.6, 10.5 or 12.1 g kg −1 ) and an antimicrobial growth promoter (0 or 60 mg kg −1 avilamycin) in piglet starter diets. Three hundred and sixty weaned piglets (24 d of age; 5.9 kg live weight) were blocked on the basis of live weight and assigned to one of six dietary treatments. The treatments were (1) 8.6 g kg −1 threonine and avilamycin, (2) 10.5 g kg −1 threonine and avilamycin, (3) 12.1 g kg −1 threonine and avilamycin, (4) 8.6 g kg −1 threonine and no avilamycin, (5) 10.5 g kg −1 threonine and no avilamycin and (6) 12.1 g kg −1 threonine and no avilamycin. The diets were formulated to have identical concentrations of digestible energy (16 MJ kg −1 ) and total lysine (16 g kg −1 ). There was no interaction between threonine and avilamycin in any performance variable measured. Neither the level of threonine nor the inclusion of avilamycin in the diet had any effect on feed intake, average daily gain or food conversion ratio. There was a significant interaction between threonine level and avilamycin inclusion in the apparent digestibility of dry matter, organic matter, nitrogen, ash, neutral detergent fibre and gross energy and also digestible energy content. In the absence of avilamycin, there was a linear increase in nutrient digestibility to increased threonine levels in the diet. However, in the presence of avilamycin there was a quadratic response to increased threonine levels. In conclusion, optimum piglet performance was achieved at a threonine level of 8.6 g kg −1 and there was no advantage to avilamycin inclusion under current conditions. Copyright © 2005 Society of Chemical Industry