Influence of vitamin E and β-carotene supplementation on spontaneous oxidised flavour of milk in dairy cows

Antioxidant vitamins A and E prevent spontaneous oxidised flavour (SOF) in the milk. Three groups of cows (6 cows/group) were supplemented with no vitamins (group 1), 1000 IU alpha-tocopheryl acetate (group 2) and 1000 IU alpha-tocopheryl acetate + 300 mg beta-carotene (group 3) per cow a day during lactation period of 90 days. Milk samples collected at fortnightly intervals were analysed for vitamin E, beta-carotene, fat content and for development of oxidised flavour, with or without Cu addition. Sensory evaluation for oxidised flavour in the milk was done by a panel of judges. Score card for SOF ranged from 0-10 with 074 as definite, 5-7 as slight and 8-10 having no defect. alpha-tocopheryl content in milk fat was significantly higher in groups 2 and 3 cows. beta-carotene supplementation did not increase the milk beta-carotene concentration. The oxidised flavour scores of group 2 and 3 (7.90 and 7.94) was significantly higher than group (7.10) on the very first fortnight of lactation. The flavour score on 90th day of lactation were 8,20, 8.88 and 9.08 in respective groups. The addition of Cu in the milk significantly increased milk fat oxidation as revealed by decreased flavour scores in all the groups. Copper induced flavour scores (CISF) were 4.70+/-0.28, 5.37+/-0.24 and 5.65+/-0.22 in groups 1, 2 and 3 respectively, showing that vitamin E supplemented cows can overcome the prooxidant effect of copper addition. Thiobarbituric acid (TBA) values of milk were similar,in all the groups. It is evident that the addition of alpha-tocopherol in the diet of lactating cows can help in improving the oxidative stability of milk. Advantage of dietary supplementation of beta-carotene was not evident.