Hair coat shedding and the relationship with productive traits in beef cattle

Abstract Text:             The objective of this study was to determine potential relationships of hair coat shedding with phenotypic data for cow age, body weight of cow at weaning, body condition score of cow at weaning, body weight of cow pre-weaning, body condition score of cow pre-breeding, pregnancy rate, birth weight of calf and calf weaning weight.  Over a three year period mature cows and replacement heifers (n=555) were scored for coat shedding on a scale from 1 to 5 at approximately 28-day intervals. A score of 5 indicated the cow had a full winter coat and a score of 1 represented a slick, short summer coat. For each cow, the first month a score of 3 (approximately 50% shed) or less was reached was considered the month of first shedding (MFS), and MFS occurred in May, June or July. Data was analyzed in general linear model or frequency and correlation procedures of SAS.  Cows exhibiting MFS in May were older (P < 0.01) compared to cows exhibiting MFS in July, and intermediate for cows exhibiting MFS in June, with ages of 6.77, 6.0 and 5.02 years of age respectively.  Calf birth weight was heaviest (P = 0.015) for cows exhibiting MFS in May and lightest for cows exhibiting MFS in July.  Calf weaning weight was similar (P = 0.8) for all MFS categories with May, June and July cows exhibiting calf weaning weights of 206.7, 205, and 204.3 kg, respectively.  Cow body weight at weaning was heaviest (P = 0.05) in cows exhibiting MFS in May (525.4 kg) and lightest in cows with MFS in July (450.6 kg).  No differences were noted in body condition score of cows at weaning or of cows pre-breeding.  Overall pregnancy rate tended to be higher (P = 0.085) for cows exhibiting MFS in May (91.4%) and lowest in cows with MFS in July (86.7%). Cow MFS was correlated (P < 0.05) with cow age (r = -0.179), calf birth weight (r = -0.092), cow body weight (r = -0.201) and pre-breeding cow body weight (r = -0.187).  In these data, MFS score had a tendency to impact pregnancy rates. Shedding of the winter hair coat was noted to be related to cow age, maternal body weight at weaning, and calf birth weight.

Keywords: Cattle, Hair coat, shedding