Effects of dietary chromium supplementation on calf performance, metabolic hormones, oxidative status, and susceptibility to diarrhea and pneumonia

The objective of this study was to determine the effect of chromium (Cr) supplementation on the health status, blood attributes, and insulin sensitivity in daily calves reared under hot summer conditions. Twenty-four newborn Holstein calves were assigned randomly to a control group (Cr-) and a group (Cr+) receiving 0.05 mg Cr-methionine per kg BW0.75. The starter feed contained 0.95 mg Cr/kg dry matter. Dietary level of Cr was within the ranges (0.08 to 1 mg Cr/kg body mass daily or more) reported to affect metabolism). Supplemental Cr was included in colostrum and milk before weaning (d 1 to 63), and in the starter feed from d 64 to 91. Dry matter intake and average daily gain increased but respiration rate was lower in Cr + calves. Cr supplementation decreased the number of days with pneumonia and medication days during the post-weaning period; however, Cr did not affect diarrhea frequency or the number of days with diarrhea. Supplementing Cr increased blood serum concentration of total proteins. Furthermore, blood serum concentration of globulins tended to increase in Cr + calves during the pre-weaning and overall periods. Cr supplementation increased catalase activity during the post-weaning period. Glucose disappearance rate tended to increase in Cr + calves. Overall, supplementary feeding of Cr may benefit growth performance and health status without a major effect on blood metabolites, antioxidant status, and insulin sensitivity in dairy calves under high ambient temperature summer conditions.