Influence of dietary gossypol of commercial and transgenic cottonseed on β-carotene and vitamin E status of dairy cows

Crossbred multiparous cows (20), divided in 2 groups of 10 each were fed on concentrate mixtures containing either commercial (group 1) or transgenic (group 2) cottonseed as protein supplement in which gossypol level was 1.23 and 1.52% (on hull free and DM basis). Concentrate mixtures were fed for 4 weeks along with berseem ad lib. and v heat straw (1 kg). Thereafter, both the groups were switched over to the concentrate mixture containing groundnut-cake as the only protein supplement and the quantity of concentrate mixture and fodder was maintained. Dietary intake of gossypol as 12 15 and 1468 ppm in groups 1 and;. respectively, Total DM intake in groups 1 and 2 was 13.05 and 13.3 5 kg day on feeding cotton seed based diets and values on feeding normal farm concentrate mixture in respective groups were similar. There was no difference between the groups for DM intake on feeding cottonseed or groundnut-cake based diets. Berseem was the major source of beta-carotene during both the trials: however, beta-carotene content was reduced during the second trial due to the maturity of crop. beta-carotene content of concentrate mixture 2 was higher than that in concentrate mixture 1 and the variation may be attributed to the type of cottonseed. Total B-carotene intake in both the groups as similar and higher in first trial than that in second one. Vitamin E content of both the concentrate mixtures was similar and total vitamin E intake was also similar in both the groups. however, intake of beta-carotene and vitamin E intake in second trial was reduced (P<0.05) in comparison to the first trial. Plasma beta-carotene was higher (9.37 mug/ml) in group 2 than that in group 1 (3.76 mug/ml) Plasma vitamin E concentration was similar in both the groups. and on shifting cows on cottonseed free diet i.e. gossypol free diet, the plasma beta-carotene and vitamin E were similar, however, plasma beta-carotene concentration vas lower than that recorded on feeding cottonseed based diet due to the less intake of beta-carotene. It can therefore, be concluded that dietary gossypol to the level of 1500 ppm of diet did not affect beta-carotene and vitamin E status of lactating cows.