Research Article

Effect of season and production system on bovine milk fat content and dispersion

Barbara Mróz, Alina Górska, Alina Adamiak

University of Natural Sciences and Humanities in Siedlce, Poland

1. Acta Sci. Pol. Zootechnica, 14(4), 2015, 131‒140

Abstract. We analyzed the effect of dairy cows management system and season on milk fat content and dispersion. The milk was collected from HF cows, Black-and-White variety, managed in 7 production farms located in central-eastern Poland. Two of the farms managed the cows in confinement (total 60 cows), whereas five other farms managed the cows in a traditional way (total 75 cows). Milk was sampled from individual cows separately during summer and winter seasons. In summer, 51 samples were collected, whereas in winter – 84 milk samples. In all, we have collected 135 milk samples. Each sample was analyzed for percentage fat content and the number and diameter of fat globules. Comparing the results of the two studied seasons studies it was found that during summer cows produce milk with a lower fat content (4.2%), though containing a higher number of fat globules in 1 ml (4.4 billion), as compared to the winter season (respectively, 4.6% and 3 billion). The differences in the percentage of fat were significant at P ≥ 0.01, while those in the number of fat globules were significant at the level of P ≥ 0.05. During the summer, we also observed a smaller percentage (6%) of the largest fat globules, i.e. those >6 µm in diameter, compared to winter (10.3%). The differences, however, were statistically non-significant. Analyzing the results of the two management systems, we noted that the cows housed in the traditional system produced milk with a lower fat percentage (4.3%) and containing more fat globules in 1 ml (3.8 billion), as compared to confinement housing (respectively, 4.5% and 3.4 billion). The differences in the percentage fat content were significant at P ≥ 0.05, while differences in the number of fat globules at P ≥ 0.01. Milk from cows managed in the traditional system was characterized by a lower content (8%) of large fat globules compared to milk of cows housed in confinement, where the such globules represented 9.2%. The differences were non-significant.

Keywords: season, management systems, milk, fat globules