Growth performance and nutrient utilisation as influenced in pigs by microbial phytase and vitamin E supplementation to a diet of high oxidative capacity

In the first of two experiments carried out with growing-finishing pigs, 40 barrows were kept from 25 to 104 kg body weight (BW). In the second experi ment, 24 pigs were kept from 75 to 104 kg BW. The pigs were fed either a ba rley-maize-based diet (C), or the same diet supplemented with either 1 200 PTU phytase (Ph) or 200 mg alpha-tocopheryl acetate-kg(-1) (E), or both (Ph E) in order to assess the effect of microbial phytase and vitamin E on grow th performance (experiment 1) and the precaecal digestibility of P, Ca, Mg, Fe, Cu, Zn, crude fat and fatty acids (experiment 2). Ph supplementation i mproved mean daily weight gain (P < 0.05) and reduced the feed conversion r atio (kg feed.kg(-1) weight gain, P < 0.01). Supplementation with alpha-toc opherol (vitamin E) did not affect growth performance. Ph inclusion improve d precaecal digestibility of P (P < 0.001) and reduced that of Zn (P < 0.05 ). The alpha-tocopherol addition improved (P < 0.01) the digestibility of Z n, whereas the a-tocopherol digestibility was not affected. The precaecal d igestibility of total lipids and the saturated, monounsaturated and polyuns aturated fatty acids were reduced (P < 0.05 to 0.001) by Ph supplementation . The combined addition of Ph and E improved the digestibility of dietary f atty acids. We concluded that dietary phytase in pig diets susceptible to l ipid oxidation demands an additional vitamin E supplementation in order to avoid detrimental effects on fat digestibility. ((C) Elsevier / Inra).