A Cross-Sectional Study of Risk Factors Affecting Milk Quality in Dairy Cows

SIMPLE SUMMARY: Modern dairy cattle farms have intensified greatly in recent years to meet the increased global demand for fresh milk. For this reason, health and welfare risks are a great concern to the dairy industry, with mastitis still being among the most significant, as it decreases milk quality and farmer profit. In the present study, 1004 dairy cows from one farm in Greece were included in the study. Data regarding the animals were collected from the farm’s database, while for each cow, health and welfare traits were recorded before collecting milk samples. Each milk sample was tested for somatic cell counts and gross milk composition, and the traits recorded were assessed as potential risk factors affecting milk quality. Higher lactation periods and teat hyperkeratosis seemed to significantly lower milk quality traits and increase somatic cell counts. Udder cleanliness and teat size also had a negative effect on protein content. These results indicate the importance of proper milking routine and hygiene and culling older cows, in improving milk quality. The relevant literature and enhanced milking and management procedures are discussed. ABSTRACT: Despite years of research devoted to bovine mastitis, the disease remains a serious problem in dairy cattle, causing economic losses to the dairy industry worldwide due to reduced milk yield, lower milk quality, drug costs and early culling of cows. The aim of this study is to determine the importance of several risk factors affecting milk quality in dairy cows, as well as to highlight proper milking techniques. A cross-sectional study was performed in one Greek dairy farm with the inclusion of a total of 1004 Holstein Friesian cows in the study. The udder and teat traits were recorded for each cow, while individual milk samples were used to estimate the somatic cell count (SCC) and gross milk composition. The traits recorded were examined as potential risk factors affecting milk quality using the Akaike information criterion (AIC) and the algorithm stepAIC to select the best linear regression model which explains the data. Overall, the prevalence of mastitis was ca. 9%. With an increase in the lactation period, the SCC increased (p ≤ 0.05) while fat (p ≤ 0.05), protein (p ≤ 0.001) and lactose (p ≤ 0.001) content decreased. Teat hyperkeratosis increased the SCC (p ≤ 0.05) and decreased P content (p ≤ 0.05). Proper husbandry management and milking procedures are considered essential to maintain milk quality of high standards.