Feed additives for swine: Fact sheets – high dietary levels of copper and zinc for young pigs, and phytase

摘要

Copper and zinc play important roles in many physiologicalprocesses. Dietary copper levels of 5 to 10 ppm and zinc levels of50 to 125 ppm are generally enough to meet the pig’s nutrientrequirement for these processes. However, when supplied at highconcentrations (100 to 250 ppm for copper and 2000 to 3000ppm for zinc), these two minerals are known to exert positiveinfluences on growth rate. In addition, copper is efficacious evenwhen antibiotics also are included in the diets. This suggeststhat the response to copper is additive to the response to antimicrobials.Response to high levels of dietary copper decreases withincreasing age and with longer periods of administration.Zinc fed at high dietary levels (2000 to 3000 ppm) reducesincidence of diarrhea and increases weight gain in newly weanedpigs. However, these high levels of dietary zinc are beneficialto pigs only during the early phases of the nursery period. Thus,feeding period for high dietary levels of zinc should be limited toapproximately 3 weeks after weaning. Additive effects are usuallynot observed in weaned pigs when high levels of copper and zincare added together. However, the data is conflicting and this observationneeds to be further investigated.4,6-8 Recent research hasindicated that feeding high levels of zinc until pigs reached 12 kg,then feeding high levels of copper for the remainder of the nurseryperiod, was the most cost-effective strategy. Pigs need dietary phosphorus for normal body maintenance andgrowth. It is an essential element that is required in many physiologicalprocesses in the pig’s body and thus suffi cient amountsmust be included in the diet. This element is abundant in mostgrains found in swine diets. However, only a small amount ofphosphorus is utilized from grains, because the majority of thephosphorus exists in a form (phytate) that is not digestible inswine. The digestibility of phytate phosphorus can be increasedwhen supplemental phytase is included in the diet.