Nutrient reduction in rations with phytase for growing pigs

Two experiments were conducted to evaluate the performance, the energy and nutrient balance and economic viability of production of growing pigs fed diets with reduced levels and phytase. In experiment 1, 60 barrows and gilts (initial weight 25 ± 1.72 kg) were housed in a randomized block design with three diets, ten replicates and two animals per experimental unit (one male and one female). One of the diets was formulated with a reduced level with phytase and evaluated in comparison to a positive-control diet that was formulated according to the nutritional recommendations for animals of this breed, and a negative-control diet without phytase. The different diets did not affect feed intake, but the diet with phytase promoted better final weight, daily weight gain and feed conversion, although it did not differ from the positive control diet. In experiment 2, 27 barrows (initial weight 49 ± 3.67 kg) were housed in random blocks with three diets and nine replicates with experimental plot represented by one animal. The diets did not affect the balance of energy and nutrients but had a significant effect on the efficiency of utilization of calcium and phosphorus, which was the lowest in animals that received the positive-control diet. Economic viability improved when nutrients were reduced and phytase was added in the ration. The addition of phytase (500 ftu/kg) in rations formulated with nutritional levels reduced for growing swines improves rearing productivity and it is economical viable. Dois experimentos foram conduzidos para avaliar o desempenho, o balanço de energia e nutrientes e a viabilidade econômica da produção de suínos em crescimento alimentados com rações com níveis reduzidos e fitase. No experimento 1, 60 suínos machos castrados e fêmeas (peso inicial de 25 ± 1,72 kg) foram alojados em delineamento de blocos casualizados, com três dietas, dez repetições e dois animais por unidade experimental (macho e fêmea). Uma das dietas foi formulada com nível reduzido e com fitase e avaliada em comparação a uma dieta controle positivo, formulada conforme as recomendações nutricionais para animais da linhagem, e a uma dieta controle negativo, sem fitase. As dietas não influenciaram o consumo de ração, porém aquela com fitase promoveu melhor peso final, ganho de peso diário e conversão alimentar, embora não tenha diferido da controle positivo. No experimento 2, 27 suínos machos castrados (peso inicial de 49 ± 3,67 kg) foram alojados em blocos ao acaso com t