Effects of supplemented organic chromium throughout dry period on early lactation milk yield of cows and also immunity of calves and their dams

The objective of this study was to determine the effects of supplemental dietary organic chromium throughout dry period on milk production of dairy cows, as well as immunity of cows and their calves. Forty-five Holstein transition cows at 60 day before the expected calving dates were randomly assigned to treatments: control, positive control (One dose Levamisole for each period at the beginning of study and one month before calving), and treatment (TMR supplementation, 5 g/day/animal organic chromium). Their calves were assigned to same groups at calving. Haematological (hemoglobin, percentage of haematocrit, MCV, MCH, MCHC, platelet, MPV, total erythrocyte count), immunological (number of total leucocyte, lymphocyte, neutrophil, and total Ig G), biochemical (ALT, AST, ALP, GGT, NEFA, BHBA and glucose) and productional (total and mean milk production for 305 days, total and mean milk production throughout one lactation, days in milk, daily mean milk production, peak milk production, colostrum total Ig G) parameters were evaluated. Blood samples were obtained from cows at prepartum 60th, 45th, 30th, 15th and 7th days, calving day and following 2 days. Likewise, blood sampling was executed from their calves at birthday and following 2 days. Also, colostrum sampling was performed for colostrum Ig G analyses. In this study, monocyte count and serum glucose concentration of control cows were higher than treatment group at prepartum (p<0.05). At calving day, although percentage of haematocrit and total erytrocyte, numbers of all immun cells except for the monocytes were less in treatment cows than the others (p<0.05); serum total Ig G and glucose concentrations were higher in treatment cows than the others (p<0,05). There were significant differences on MCH, serum glucose concentration, as well as activity of ALT and AST at postpartum first day; on number of total erytrocyte at postpartum second day; on percentage of haematocrit at both days (p<0.05). There were significant differences on number of total leucocyte and neutrophile, MCH, activity of ALT at birthday; on number of total leucocyte and MCV at postpartum for calves (p<0.05). Although days in milk (DIM) of treatment cows were shorter than control group (p<0.001), there were no significant differences on other milk production parameters and colostrum Ig G concentrations. These data concluded that although supplemental chromium affected positively number of erythrocytes and production of hemoglobin, there was no treatment effect on serum biochemical parameters. However, shorter DIM for treatment cows suggested that prepartum supplemental dietary chromium would be provided earlier conception and completion of lactation with optimal DIM. Nevertheless, further studies are needed for understanding to detailed mechanism.