Özet:

Milk is composed of more than 400 fatty acids, approximately 100 proteins and peptides, lactose, vitamins and minerals. These components have a high bioavailability and health-promoting properties to humans. They also influence technological usefulness of milk for processing. The aim of the study was to determine the influence of cow’s age, level of productivity and lactation phase on milk composition with particular emphasis on the share of protein fractions and lactoferrin in milk of Polish Holstein-Friesian cows. Milk samples were collected from primiparous (P; n = 60) and multiparous (M; n = 60) cows in three phases of lactation (I – 30–60 days; II – 90–120 days; III – 210–240 days) with differentiation on cows with low (L; < 30 kg/milking) and high (H; > 30 kg/milking) performance. Lower (P  ≤  0.01) level of α-casein was found in milk from cows ML I and MH I comparing with primiparous cows in this phase of lactation. Milk from cows PH III was characterised by lower (P  ≤  0.05) share of α-lactalbumin comparing with milk from cows in I stage of lactation in all groups. It was observed that in subsequent phases of lactation milk was characterized by higher content of lactoferrin. In general, in multiparous cows somatic cell count (SCC) was higher comparing with primiparous cows. The obtained results can be explain by the greater number of infections of the mammary gland in older cows so the level of antibacterial components increases as well as the fact that with lactation phases mammary gland becomes more and more susceptible.

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