Microbial phytase combined with amino acid supplementation reduces P and N excretion of growing and finishing pigs without loss of performance

Abstract

The objective of this study was to evaluate the effect of a combined low-protein (CP) lowphosphorus (P) diet, supplemented with limiting amino acids and microbial phytase, on performance, nutrient utilization and carcass assessment of grower-finisher barrows. 4 · 6 crossbreed barrows were continuously housed in metabolism cages from 25 to 100 kg live weight and were fed diets, either conventional according to recent nutrient recommendations (A) or protein reduced (B) or protein and phosphorus reduced diets (C) based on barley (59-80%), maize (15%) and soybean meal (23-2%). Diet A (positive control) contained in fresh matter 18.5%, 15.6% and 13.6% CP and 0.59%, 0.51%, 0.50% P (growth phases I: 25-50 kg, II: 50-75 kg, III: 75-100 kg weight). Diet B was low in CP (14.2%, 13.4%, 11.0%), diet C low in CP and low in P (CP: as B, P: 0.46%, 0.41%, 0.32%). Diet D served as a negative control (CP and P as C). To diet B the limiting amino acids lysine, methionine, threonine and trypthophan were added to meet the levels in diet A, to diet C the limiting amino acids and 800 FTU Aspergillus-phytase per kg were supplemented. At the end of the balance periods of about 100 (A,B,C) or 133 (D) days, the barrows were slaughtered at 100 kg live weight, the carcasses scored and loin, biceps femoris, os femoris and phalanx prima IV were analysed for their nutrient (dry matter, protein, fat) or mineral (ash, Ca, P, Mg, Fe, Zn) composition. In contrast to the basal diet D, the CP or P reduction in diets B and C did not negatively affect growth, feed efficiency, nitrogen retention or overall carcass performances of the pigs. With the low CP diets B and C, N excretion via the urine was significantly reduced and thus N excretion per unit weight gain was decreased by about 30%. The addition of microbial phytase (C) increased apparent digestibility of P significantly between 25% (growth phase III) and 50% (growth phase II). In spite of 25% reduction of P intake (C), the absolute daily P retention did not differ between treatments. Thus phytase supplementation in diet C reduced P excretion per unit weight gain by about 35% (I, II) to 44% (III) as compared with A and B. Similarly, phytase raised apparent digestibility of Ca by about 25% and Zn by about 80%. Generally, the carcass and meat characteristics were not affected by any of the diet strategies employed in this experiment. Mineralization (bone weight, ash, Ca, P, Mg) of the os femoris and phalanx prima IV were also similar in all treatment groups. However, phytase supplementation led to significantly increased zinc concentration in bones, indicating considerably improved zinc release from the phytate complex. In contrast, Fe incorporation into the os femoris was significantly reduced in the phytase group. In general, the low CP and low P feeding regimen introduced in this experiment offers substantial benefits in maintaining a sustainable environmentally-friendly pork production.

Nutrient reduction in rations with phytase for growing pigs

“…Furthermore, the similarity between the effects of the diet supplemented with phytase and those of the positive-control diet can be explained by the fact that the difference in dietary energy was too small to influence the energy digestibility. Similar results have been found by Walz & Pallauf (2002), who provided diets supplemented with phytase to growing pigs and found no variation in the digestibility of dry matter, digestible energy and metabolizable energy. Likewise, O'Quinn et al (1997) obtained similar results for energy-related variables.…”

“…Different results have been reported by Walz & Pallauf (2002), who observed an increase of 16% in nitrogen retention in pigs fed low-nutrient diets with or without phytase supplementation. Likewise, Bruce & Sundst (1995) have reported that phytase influences nitrogen retention in pigs.…”

Níveis de proteína e fósforo em rações com fitase para frangos de corte, na fase de 14 a 21 dias de idade: 2. valores energéticos e digestibilidade de nutrientes

“…Isso, possivelmente, decorreu do fato de a fitase liberar Zn do ácido fítico, aumentando sua concentração no intestino e resultando em inibição de sua absorção pelo excesso (Sandströn & Cederblad, 1980, citados por Lönnerdal, 2000. No entanto, os resultados obtidos por Walz & Pallauf (2002), para suínos em crescimento e terminação, mostraram que a redução da PB e Pd, combinada com a suplementação de aminoácidos e fitase, aumentou a retenção de Zn.…”

Níveis de energia metabolizável em rações formuladas com base no conceito de proteína ideal e suplementadas com fitase para leitões dos 15 aos 35 kg

“…Kerr et al(2003 a,b), em experimento com animais em crescimento, verificaram que rações com baixa proteína bruta suplementadas com aminoácidos es senciais resultaram em menor concentração de uréia no sangue. Walz & Pallauf (2002) constataram que, para suínos em crescimento, rações com níveis reduzidos de PB, Pd e Ca suplementadas com aminoácidos sintéticos e fitase reduziram em 35% o nível de uréia plasmática em comparação àquelas formuladas com os níveis de PB, Pd e Ca recomendados e sem suplementação de aminoácidos sintéticos.…”

“…Es te resultado pode ser atribuído a dois fatores: animais alimentados com rações com nível reduzido de PB, com aplicação do conceito de proteína ideal e suplementação de aminoácidos sintéticos consumiram rações com adequada relação dos aminoácidos essenciais; ou a fitase causou hidrólise do ácido fítico, liberando fósforo, cálcio e outros minerais, que podem ter se complexado ao ácido fítico, tornando-se disponíveis para o metabolismo. Walz & Pallauf (2002), em experimento com suínos em crescimento, verificaram que rações com níveis reduzidos de PB, Pd e Ca combinados à suplementação de aminoácidos sintéticos e fitase promoveram desempenho, consumo de energia metabolizável e utilização de energia para ganho semelhantes. Além disso, Ludke et al (2000) observaram que, ao incluírem fitase nas rações, o desempenho dos leitões melhorou e que a enzima foi mais eficaz nas dietas com 16% PB em comparação a uma ração com 18% PB.…”