Dose dependent efficiency of supplemented microbial phytase in pigs with 40, 70, and 100 kg body weight

Three experiments were conducted with crossbred growing pigs weighing about 40, 70, and 100 kg. Diets were different in composition and supplied energy and nutrients as recommended with the exception of P and Ca. They did not contain P from mineral sources. Titanium dioxide was used as the indigestible marker. Four treatments were considered in each experiment, and they differed in the supplementation of Aspergillus niger phytase only: 0, 100, 250, and 500 U/kg. Twelve (exp. 1 and 2) and ten (exp. 3) individuals were allocated to each treatment. Pigs were kept individually, and diets were offered ad libitum for 17 days. During the last 7 days on treatment, faecal material was spot sampled twice daily from each individual. Efficiency of phytase was evaluated based on the increase in content of digestible P. Digestibility of P in the unsupplemented basal diets varied between 22 and 40% between experiments. The dose-response relationships were non linear and could be described with exponential functions. The maximum increase in the content of digestible P in the three experiments was 0.86, 0.63, and 0.46 g/kg diet. Equivalency values were calculated on the basis of the functions for different supplementation levels. The experiments did not confirm the hypothesis that the efficiency of microbial phytase in fattening pigs depends on the body weight of the pigs.

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