Genetic Parameters Associated with Type Traits Scored on an Ordered Scale During Second and Fourth Lactation

Abstract

Sixty subjective and linearized type scores were recorded on 3730 and 1397 Holstein cows during second and fourth lactations. For genetic parameters the data were analyzed by paternal half-sister analysis within parity. The second and fourth lactations data represented 99 and 53 sires. Of six functional traits, milking speed had the highest heritability for second (.11) and fourth (.13) lactation. Feet and leg traits generally had the lowest heritabilities in second (range 0 to 10%) and fourth (range 0 to 15%) lactation. Largest heritabilities in second lactation were head length (.18), udder depth (.17), height (.17), and body length (.14). In fourth lactation the largest heritability was for head length (.24). Most phenotypic correlations were near zero. However, some udder traits and traits associated with body size had moderate correlations. The largest phenotypic correlation in second lactation was between body length and height (.55). Udder depth had large genetic correlations with many traits (e.g., fore udder length, fore udder smoothness, rear udder height, rear teat placement, width of hips, height). In second lactation, the largest phenotypic correlations involving udder depth were for depth and fore udder smoothness (.34) and depth and rear udder balance (.28).