Supplementation of Cr Methionine During Dry Period of Dairy Cows and Its Effect on Some Production and Biochemical Parameters During Early Lactation and on Immunity of Their Offspring.

This study aimed to investigate the effect of dietary chromium methionine (Cr-Met) supplementation on the production and immunological parameters of dairy cows during the dry and postpartum period and their offspring. Forty-five Holstein transition cows were randomly assigned to experimental groups with control, positive control (levamisole-injected cows), and treatment groups (5 g dietary Cr-Met/day/cow). Production, immunological, and biochemical parameters were analyzed during the dry and postpartum period. Result revealed that in dry cows, monocyte count and serum glucose level significantly (p < 0.05) decrease in Cr-supplemented cows over control. Similarly, after parturition, the numbers of all immune cells (except monocytes) decreased significantly (p < 0.05); however, serum IgG, ALT, AST, glucose levels, and total leucocyte, neutrophil, and leucocyte count were increased significantly (p < 0.05) in Cr-supplemented cows over the control group. Days in milk (DIM) of treatment cows were significantly (p < 0.05) decreased over the control group; however, no significant (p > 0.05) differences were observed on milk production, colostrum, and IgG concentrations. As a conclusion, the supplementation of Cr had positive effects on immune cells of cows after parturition; however, serum biochemical parameters remained unaffected. Also, there were significant differences on the number of total leucocyte and neutrophil, on the activity of ALT at birthday, and on the number of total leucocyte at postpartum for calves.