Fertility improvement in cross-bred dairy cows through supplementation of Vitamin E as antioxidant

Reproductive cyclicity of cross-bred cattle has been reported to be reduced due to stress. this study was conducted to investigate the role of vitamin e in combating stress. the experiment was conducted on 36 lactating dairy cows,comprising indigenous (9 sahiwal,9 achai),9 cross-bred (sahiwal x holstein frisian) and 9 holstein frisian located at two state dairy farms. vitamin e was supplemented in feed at a dose rate of 1000 iu/ cow/ day for 40 days. sampling was conducted on day-zero (control),day-20 and day-40 of vitamin e supplementation during the diestrus phase. concentrations of sod and gpx increased significantly (p<0.001) with vitamin e supplementation. breeds also varied in sod and gpx activities (p<0.05 and p<0.001 respectively). the stress markers (plasma mda,hsp-70 and serum cortisol) decreased significantly with vitamin e supplementation while breeds also showed variation in these parameters (p<0.001). progesterone concentration increased significantly (p<0.001) with vitamin e supplementation showing significant variation (p<0.05) among breeds. number of follicles decreased significantly with vitamin e supplementation (p<0.01),highest in cross-bred cows indicating quality graafian follicles with supplementation. the stress markers (cortisol,hsp-70 and mda) were positively correlated mutually while negatively with antioxidant markers. progesterone was positively correlated with antioxidant markers. it was concluded that holstein frisian and crossbred cows showed more favorable response to vitamin e supplementation in respect of expression of stress and reproductive markers suggesting regular feeding of antioxidant to these breeds for better performance. copyright 2016 zoological society of pakistan.