Effects of dairy cow diet supplementation with carrots on milk composition, concentration of cow blood serum carotenes, and butter oil fat-soluble antioxidative substances.

Fat-soluble constituents of milk - β-carotene and α -tocopherol - are essential for quality and nutritional value of milk and dairy products. Provision of fat-soluble antioxidants and vitamins such as carotenoids and vitamin E necessary for cow organism and milk synthesis depends on their concentration in fodder. The aim of this study was to estimate the effect of cow feed supplementation by carrots on the total carotene concentration in cow blood serum, on fat, protein, lactose concentration in milk, and milk yield, as well as to investigate the effects on β - carotene and α -tocopherol concentration in butter oil and intensity of its yellow colour. A total 20 cows of Latvian brown ( n = 8) and Danish red ( n = 12) breed were divided into control (CG) and experimental group (EG). In the EG, cow feed was supplemented with seven kg of carrots per cow per day for six weeks at the end of the indoor period (March -May). Milk samples from indoor period ( n = 100) and grazing ( n = 20) were used for butter oil extraction. The carotene concentration observed in blood of animals before the experiment was insufficient taking into account that the reco mmended β -carotene concentration in serum is above 3.0 mg l -1 level. During indoor period the increase in carotene concentration in blood of cows was significant in both groups ( P 0.05 ). At the same time it contributed in more stable β -carotene, as well as 30% higher α -tocopherol concentration and more intense yellow colour of butter oil samples during the indoor period of the experiment ( P < 0.05).