The Effect Of Chromium Source On Performance Of Lactating Cows Under Heat Stress

Three experiments were conducted to evaluate on the effect of dietary chromium as chromium - picolinate or chromium-lysine in dairy cows'diet.Experiment 1: The effect of chromium-picolinate and chromium-lysine on performance of Holstein cows under non-heat stressSeventy five multiparous lactating Holstein cows (80 days post-partum) used in this study were divided equally into three groups (25 cows/treatment) and were randomly allocated to one of three treatment diets. Diet I, basal diet with chromium (chromium-picolinate) added at a recommended level (0.6g /head per day); Diet II, basal diet with chromium (chromium-lysine) added with the same level (0.6g /head per day); Diet control was basal diet without chromium added; The average temperature–humidity index (THI) was 57.2 units. In comparison with the Diet control, we found that: 1)milk production of DietⅠandⅡwere respectively increased by 9.2% and 8.6%(p<0.01); 2) glucose conentration in blood of DietⅠand DietⅡwere respectively increased by 0.52mmol/L and 0.68mmol/L(p<0.01), while triacylglycerol (TAG) concentration were respectively dicreased by 0.02 mmol/L and 0.03mmol/L(p﹤0.05); 3) the IgG concentration in blood of DietⅠand DietⅡwere respectively increased by 2.96g/L and 3.10g/L(p﹤0.05), while the cortisol concentration in blood of DietⅠand DietⅡwere respectively decreased by 7.21nmol/L and 4.92nmol/L, but the difference between each groups was not significant in statistics (p>0.05); 4) adding chromium to the diet of lactating cows show little effect on DMI and blood serum level of protein, urea nitrogen, insulin ,cholesterol and Na~+;Experiment 2:The effect of chromium-picolinate and chromium-lysine on...