The relationship between somatic cell count, milk production and six linearly scored type traits in Holstein cows

Test-day records of somatic cell count (SCC), milk yield, fat and protein content and six linearly scored type traits (fore udder attachment, udder depth, central ligament, rear udder height, front teat placement, teat length) of 22 613 first lactation cows from 117 herds were included in this study. SCC was log-transformed into somatic cell score (SCS). Milk yield was standardized as follows: MILK = milk yield (fat content + protein content)/(3.8 + 3.2). For each analyzed type trait, cows were assigned to one of the three levels according to linear type score: level 1 (score 1 and 2); level 2 (score 5 and 6); level 3 (score 8 and 9). A linear model was used to estimate the effect of different type traits on MILK and SCS. The highest values of SCS were found for the first levels. The differences between the first and second level were on average 0.33, 0.54, 0.28, and 0.36 for fore udder attachment, udder depth, central ligament and rear udder height, respectively. The cows with deep udders, weak central ligaments and fore attachments and low rear udder height showed the highest SCS. Low SCS appeared to be associated with an intermediate distance between the front teats and longer teats. The third level of udder depth (shallow udder) had low MILK. Rear udder height showed low MILK for the first level (low height) with the highest MILK values for the third level (high height). The average difference was 3.3 kg.