Effects of copper hydroxychloride and choice white grease on growth performance and blood characteristics of weanling pigs kept at normal ambient temperature or under heat stress

Abstract

An experiment was conducted to test the hypothesis that copper (Cu) hydroxychloride improves growth performance and blood characteristics, and reduces diarrhea incidence in weanling pigs without or with exposure to heat stress. One hundred sixty pigs (6.14 ± 0.90 kg) were allotted to a 2 × 2 factorial arrangement with 2 levels of choice white grease (CWG; 0 or 50 g/kg) and 2 levels of Cu from Cu hydroxychloride (0 or 100 mg/kg). There were 5 pigs per pen and 8 pen replicates per diet. Fecal scores were visually assessed using a score from 1 to 5 (1 = normal feces to 5 = watery feces). On day 40 until the end of the experiment, ambient temperature was increased from 24 °C to 32 °C to create a mild heat stress. On day 14, day 28, day 40, and on day 44, blood samples were collected from 1 pig per pen and tumor necrosis factor-α (TNF-α), peptide YY, immunoglobulin G, blood urea nitrogen, total protein, and albumin were analyzed. Results indicated that there were no interactions between CWG and Cu hydroxychloride for overall growth performance. Greater (P < 0.05) gain:feed was observed from day 29 to 40 and from day 41 to 44 for pigs fed diets with 50 g/kg CWG compared with pigs fed diets without supplemental fat. Average daily gain was greater (P < 0.05) from day 15 to 28 and also during exposure to heat stress, and fecal scores were reduced over the entire period (P < 0.05) for pigs fed diets with Cu hydroxychloride compared with pigs fed diets without Cu hydroxychloride. There was also an increase (P < 0.05) in concentration of peptide YY and a reduction (P < 0.05) in TNF-α concentration on day 14 for pigs fed Cu hydroxychloride diets compared with pigs fed diets without Cu hydroxychloride. This may be attributed to the effect of Cu in enhancing the expression of hypothalamic appetite regulators and its bacteriostatic property in reducing inflammation caused by pathogens. In conclusion, supplementation of Cu hydroxychloride to diets fed to weanling pigs without or with addition of CWG reduces diarrhea incidence and improves growth performance and some blood characteristics.