Abstract #377

# 377
Relationships between yield, fitness, and type traits in US Brown Swiss.
Keith D. Gibson*1, Chad D. Dechow1, 1The Pennsylvania State University, State College, PA.

Genetic parameters have often been estimated for the US Holstein population, but infrequently for Brown Swiss. The objective of this research was to evaluate heritabilities and correlations of fitness with yield and type traits for Brown Swiss cattle born in 2000 and later. The data consisted of 105,164 first through fifth lactation yield and somatic cell score (SCS) records from 45,464 cows with 82,761 d open (DO) and 31,105 productive life (PL) records. Approximately 52,250 of the records had values for 17 type traits and 41,074 had values for milking speed. These data were analyzed using a series of 3 trait models in ASREML that included fixed effects for lactation, age, and herd-calving cluster. Random effects were animal, permanent environment, and residual. The heritabilities of milk, fat, and protein yield were 0.30, 0.20, and 0.20, respectively. The heritabilities of PL, DO, SCS, and milking speed were 0.11, 0.03, 0.12, and 0.26, respectively. Yield traits had strong positive correlations with PL (0.63 to 0.71), whereas DO (−0.69) and SCS (−0.60) had strong negative correlations with PL. Milking speed had a moderate positive correlation with PL (0.26) and DO (0.19) and a slight negative correlation with SCS (−0.10). Yield traits had a slight unfavorable genetic correlation with DO (0.11 to 0.18). However, rear udder width (0.55), final score (0.45), body depth (0.43), dairy form (0.43), rear udder height (0.32), and stature (0.27), were more unfavorably correlated with DO than was yield. Yield was positively correlated with rear udder height (0.19 to 0.25) and rear udder width (0.34 to 0.48), and negatively correlated with udder depth (−0.40 to −0.24) and fore udder attachment (−0.21 to −0.04). However, udder depth (−0.26) and fore udder attachment (−0.14) were more favorably correlated with SCS than rear udder height and rear udder width (−0.02 and 0.18, respectively). Of the udder traits, fore udder attachment, rear udder width, rear udder height, and udder cleft were most favorably correlated with PL (0.31 to 0.44). These updated genetic parameters will allow for improved genetic selection in the Brown Swiss breed.

Key Words: Brown Swiss, correlation, productive life