Microbial phytase in finisher diets of White Pekin ducks: effects on growth performance, plasma phosphorus concentration, and leg bone characteristics

Abstract

Two experiments (Exp.) were conducted to determine the growth response of White Pekin ducks to inclusion of microbial phytase in finisher diet. In Exp. 1, 1-d-old male ducks (240 total) were reared in litter-floor pens and fed regular starter diet until 3 wk of age. At 3 wk of age, ducks were randomly divided into six groups of 10 ducks each and each group was fed one of four diets. Three finisher diets containing 16% CP and 0.18% available phosphorus (AP) without supplemental P were formulated with microbial phytase (Natuphos) added at 0, 750, or 1,500 phytase units/kg of diet. The fourth diet was a control finisher diet that was supplemented with dicalcium phosphate (DCP) to supply dietary AP of 0.41%. Group BW and feed intake were measured weekly to assess growth response. At 6 wk of age, leg bones (tibia, femur, metatarsus) from five randomly selected ducks were removed and analyzed for bone characteristics. In Exp. 2, a total of 120 ducks reared as in Exp. 1 were randomly divided into six groups of five ducks each and fed one of four diets. A basal finisher diet was formulated to contain 16% CP and 0.18% AP. Monosodium phosphate was added to the basal diet to give dietary AP levels of 0.18, 0.27, and 0.36%. The fourth diet was the basal diet supplemented with microbial phytase (750 phytase units/kg of diet). Ducks were fed these diets from 3 to 6 wk of age. At the end of the study, ducks were bled by cardiac puncture and blood plasma was analyzed for P concentration. Leg bones from all ducks were removed and analyzed for bone characteristics as in Exp. 1. Feed intake increased linearly with increased level of dietary phytase, whereas the weight gain response was quadratic only during the last week of Exp. 1. In Exp. 2, there was a quadratic response for weight gain due to dietary AP. Weight gain due to phytase (750 units) was not different from ducks fed diets at 0 or 0.18% AP. Plasma P concentration increased linearly as dietary AP increased. Plasma P levels of ducks fed phytase were similar to those of ducks fed 0.18% AP but lower than in ducks fed 0.27% AP. Estimates of AP resulting from the addition of 750 units of phytase to basal diet were 0.05 and 0.07% based on plasma P concentration and weight gain, respectively. Using regression analysis, the AP due to phytase effect in the diet was estimated to range from 0.06 to 0.08%. Results suggest that phytase can be used in finisher diets similar to the one used in this study for ducks from 3 to 6 wk of age to improve growth performance and leg bone development similar to ducks fed diets supplemented with P from inorganic sources.

Reaction of laying hens to low phosphorus diets and addition of different phytase preparations

“…In conclusion it can also be stated that the bone quality parameters of laying hens are more rational and useful indices for estimation of phosphorus availability and phytase efficiency than egg shell characteristics. A similar conclusion was drawn by Orban et al (1999) and Um and Paik (1999).…”

Phosphorus equivalency value of an Escherichia coli phytase in the diets of White Pekin ducks

“…The enzyme phytase hydrolyzes phosphate groups from the phytin molecule potentially making this hydrolyzed P available for utilization in the body . The dietary addition of exogenous phytase has been shown to reduce P excretion through improving the utilization of phytate-bound P in pigs , broiler chickens (Dilger et al, 2004), and ducks (Orban et al, 1999;Rodehutscord et al, 2006).…”

Efeito De Níveis De Fósforo Não-Fítico E De Fitase Sobre a Tíbia De Frangos De Corte

“…As dietas experimentais fareladas eram isonutritivas e foram formuladas de acordo as recomendações nutricionais e a composição dos ingredientes de Rostagno et al (2005), exceto para os valores de fósforo não-fítico.…”

“…Além disso, esse mineral também desempenha um papel crítico no metabolismo de carboidratos, proteínas e lipídios, principalmente na fosforilação oxidativa (Hatten et al, 2001). O não fornecimento de quantidades adequadas de P pode resultar em pior desempenho, deformidades ósseas, maior condenação de carcaça e alta mortalidade (Panda et al, 2007).…”

“…O ácido fítico também se liga a outros minerais, tais como Ca, Fe, Zn, Mn, Cu e Co, podendo reduzir a disponibilidade desses minerais (Shelton e Southern, 2006). Devido à presença do ácido fítico, a disponibilidade de P em alimentos comumente usados para aves é de, aproximadamente, 30 a 40% (NRC, 1994;Rostagno et al, 2005). Sendo assim, fósforo inorgânico (Pi) é adicionado às dietas de monogástricos para compensar a utilização ineficiente do P fítico (Jendza et al, 2006).…”