Factors influencing the content of vitamins A and E in sheep and goat milk

Abstract

The content of lipophilic vitamins A and E was determined in samples of sheep and goat milk of different breeds coming from 9 farms in central, eastern, and southern Bohemia. Samples were collected throughout the period of lactation (from April to September). Vitamins A and E were determined by HPLC using DAD and FLD detectors. Vitamin A was determined in all samples but only α-tocopherol (out of various forms of vitamin E) was detected in all samples. The total average content of vitamins A and E in raw milk of all sheep breeds during lactation was 0.93 ± 0.07 and 2.93 ± 0.87 mg/kg, levels of these vitamins in goat milk were 0.79 ± 0.08 and 1.29 ± 0.35 mg/kg, respectively. The results showed a significantly medium and strong correlation between the content of vitamin A and E and the content of fat (R2 = 0.57 and 0.75, respectively). The year did not have any statistically significant influence on the content of monitored vitamins. The content of both vitamins is dependent on the phase of lactation. The levels of vitamins A and E were significantly lower in the early phase and significantly higher in the late phase of lactation. The amount of monitored vitamins slightly decreased during pasteurisation. A strong decrease in the content of both vitamins was observed during the first two weeks after milk storage in a freezing box at the temperature of -20°C (about 11-55%).