Effects of Dietary Copper Levels on Growth Performance and Response to Lipopolysaccharide Challenge in Nursery Pigs from Sows Fed Either High or Low Copper Diets

At weaning, a total of 32 piglets (half barrows and half gilts) were selected from multiparous sows fed diets supplemented with copper at either 20 or 120 ppm Cu throughout gestation and lactation. These piglets were blocked by BW and sex, and then randomly allotted to 2 dietary treatments (supplemented with 20 or 220 ppm Cu from CuSO₄) as a split-plot design of sow diet (main plot) and nursery diet (subplot) with 4 pens/treatment and 2 pigs/pen. The diets were fed in two 2-week phases, pigs and feeders were weighed weekly and blood samples were collected on d 0, 14, and 28. Upon completion of the growth trial, one pig from each pen was moved to another pen to singly house the pigs, and all pigs were deprived of feed overnight. The next morning, the pigs from each original pen were injected with either lipopolysaccharide (LPS: 50 µg/kg of BW) or PBS solution; and then pigs were allowed to access the same diets as in the growth trial. Growth performance, respiratory rate, rectal temperature, and plasma cortisol level were measured right before injection, and every 2 h until 12 h after injection. Piglets from sows that received the high Cu diet had greater ADG and ADFI during d 0 to 7, d 0 to 14, and overall period (P < 0.05), and higher G:F during d 0 to 14 (P = 0.014) than those from sows that received the low Cu diet. The piglets injected with LPS had lower BW gain from 2 to 6 h, lower feed intake, higher rectal temperature, and greater plasma cortisol levels from 2 to 12 h after injection (P < 0.10) when compared to piglets injected with PBS. The piglets from sows that received the high Cu diet had heavier BW from 0 to 12 h, greater BW gain from 6 to 10 h, higher rectal temperature from 0 to 12 h, and greater plasma cortisol levels at 2, 6 and 10 h after injection (P < 0.10) than those from sows that received the low Cu diet. The supplementation of Cu at 120 ppm to the sow diet improved growth performance of nursery pigs, and resulted in different responses to LPS challenge. However, the Cu levels of the nursery diets did not affect the growth performance of piglets during the growth trial or response of piglets to LPS challenge.