Macro- and micromineral composition of pigs from birth to 145 kilograms of body weight

Body mineral composition was determined in 81 pigs killed at birth, weaning (28 d), and at approximately 15-kg intervals to 145 kg of BW. Total body components, including internal tissue, whole blood, and hair, were wet-ashed and analyzed for their mineral contents with the inductive coupled plasma method, except for Se, which was determined by fluorometric analysis. The results demonstrated that the body protein:ash ratio increased from birth to 20 kg BW, remained constant to 125 kg, but then declined to 145 kg BW (P .01). The K:Na ratio increased from birth to 105 kg BW and then reached a plateau (P .01). The Ca:P ratio decreased from birth to 20 kg then remained relatively constant to 90 kg BW, whereupon it increased (P .01). These ratios reflected the rate of development of muscle and bone tissue and the higher soft tissue requirement for P and K during early growth. When expressed on a fat-free tissue basis, body Na was higher than K at birth, but thereafter body K increased linearly (P .01) and Na content declined (P .01). When Mg, Mn, Mo, and Cr were expressed on a fat-free empty body weight basis, each increased from birth but they maintained the same relative concentrations from 20 to 145 kg BW (P .01). Body Fe increased from birth to 20 kg BW but then gradually declined to 145 kg BW (P .01), whereas Zn increased to 145 kg BW (P .01). Selenium increased from birth to weaning and again after 105 kg BW (P .01). The amount of Co in the fat-free empty body increased linearly (P .01) with increasing pig weight, and body Cu decreased to 75 kg BW and then reached a plateau (P .01). The nonessential elements Al, Sr, and Sn increased dramatically from birth to weaning with a low rate of increase from 8.5 to 145 kg BW (P .01), but Sn decreased after weaning (P .01). The nonessential elements generally had a more variable concentration than the dietary essential trace minerals.