title: Effect of high phytase inclusion rates on performance of broilers fed diets not severely limited in available phosphorus.
abstract: Phytate is not only an unavailable source of phosphorus (P) for broilers but it also acts as an anti-nutrient, reducing protein and mineral absorption, increasing endogenous losses and reducing broiler performance. The objective of this study was to investigate the anti-nutritional effects of phytate by including high levels of phytase in diets not severely limited in available P. A total of 768 male Arbor Acres broilers were distributed in six treatments of eight replicate pens of 16 birds each consisting of a positive control diet (PC), positive control with 500 FTU/kg phytase, negative control (NC) diet with lower available P and calcium (Ca) levels and the same NC diet with 500, 1,000 or 1,500 FTU/kg phytase. Body weight gain (BWG), feed intake (FI), feed conversion ratio (FCR) and mortality were determined at 21 and 35 d of age while foot ash was determined in four birds per pen at 21 d of age. FI, FCR and foot ash where not affected by the lower mineral diets at 21 d of age nor by the enzyme inclusion but broilers fed lower Ca and available P diets had lower BWG. At 35 d of age no difference was observed between broilers fed the positive or NC diets but broilers fed 500, 1,000 and 1,500 FTU/kg on top of the NC diet had better FCR than broilers fed the positive control diet. When compared to birds fed a diet adequate in P, birds fed the same diet included with 500, 1,000 and 1,500 FTU/kg of phytase in marginally deficient available P and Ca diets had an improvement of performance. These results support the concept that hydrolysing phytate and reducing the anti-nutritional effects of phytate improves bird performance on marginally deficient diets that were not covering the P requirement of birds.
authors: AB Vista Feed Ingredients, Marlborough, Wiltshire, SN8 4AN, UK.
authors: T T
authors: TT
authors: Dos Santos
authors: AB Vista Feed Ingredients, Marlborough, Wiltshire, SN8 4AN, UK.
authors: S
authors: S
authors: Srinongkote
authors: AB Vista Feed Ingredients, Marlborough, Wiltshire, SN8 4AN, UK.
authors: M R
authors: MR
authors: Bedford
authors: AB Vista Feed Ingredients, Marlborough, Wiltshire, SN8 4AN, UK.
authors: C L
authors: CL
authors: Walk
keywords: Broiler; Performance; Phytase; Phytate