Effects of the Calcium and Phosphorus Ratio in High Zinc Diets on Performance and Nutrient Digestibility in Weanling Pigs

摘要

Forty-eight crossbred (Landrace x Yorkshire) barrows, weighing an average of 7.55 ? 0.54 kg, were allotted to one of four dietary treatments containing approximately 2,400 ppm Zn. Four corn-soybean meal based diets (20.4% crude protein and 0.60-0.63% phosphorus) were formulated to contain 0.83 % Ca (Ca:P, 1.31:1), 0.91 % Ca (Ca:P, 1.51:1), 1.01 % Ca (Ca:P, 1.65:1) or 1.17 % Ca (Ca:P, 1.91:1). Daily gain and feed intake were unaffected by dietary treatment (p>0.05). Feed conversion was affected quadratically (p<0.01) for the periods from 0 to 14 d, 14 to 28 d and overall by increasing dietary calcium concentration. There was no effect of calcium level on the digestibility of dry matter, crude protein, acid detergent fibre, energy, ash, phosphorus, zinc and iron. The digestibility of fat and calcium in the 1.17 % calcium diet was significant lower than for the other diets (p<0.05). In addition, the digestibility of copper in the 0.83 % calcium diet was significantly lower than for the 1.01 % calcium diet (p<0.05). There was no effect of calcium level on the digestibility of amino acids except for arginine with the digestibility of arginine in the 1.041 % calcium diet being significantly lower than the other diets (p<0.05). In conclusion, feeding higher calcium levels than NRC requirement in diets containing pharmacological levels of Zn level improved feed conversion. The results suggest that the level of calcium recommended by NRC for weanling pigs may be insufficient for optimal performance when pigs are fed diets containing pharmacological levels of zinc.