938
Relationship of physical characteristics and reproductive status in crossbred Angus replacement heifers
The objective for this study was to measure physical characteristics of developing replacement heifers and to determine if these traits were related to reproductive status at breeding. Contemporary Angus based replacement heifers (n = 89) were managed on pastures containing endophyte infected tall fescue at the University of Arkansas Beef Cattle Research Center near Fayetteville, Arkansas. Measurements that were recorded for each heifer at weaning, yearling, and prebreeding included body weight, pelvic area, hip height, hip width, reproductive tract score, rump fat, back fat, rib eye area, and coat shedding score. A group of heifers (n = 26) were determined to be unsatisfactory for exposure to breeding (NE). Pregnancy status was determined for the remaining heifers (n = 63) following AI and pasture exposure to fertile bulls in a 60 day breeding period. No physical differences were found among the heifers that were exposed and did conceive (EC) (n = 32) compared to heifers exposed that did not conceive (EDC) (n = 31). Mean pelvic height was greater for EC heifers (38.68 ± 4.00) when compared to the NE (35.51 ± 4.00) and EDC (38.00 ± 4.00) heifers (P = 0.056). The NE group had a significantly greater mean coat shedding score than either EDC (P < 0.01) or EC heifers (P < 0.01), with EC heifers having the lowest mean coat shedding score (3.05, 2.62, vs. 2.52 ± 0.91, respectfully). The physical characteristics including body weight, hip height, and rump fat that were measured for the NE group displayed an inverse trend to that of coat shedding score. The NE group exhibited lower (P < 0.05) values across all physical measurements compared to EC and EDC heifers. Coat shedding score was further analyzed by dividing the heifers data into two groups, with group one (g1) having coat scores 3 or less and group two (g2) having coat scores 4 or 5. Group one heifers were 10.38±7.23, 21.48±7.78, and 30.18±7.96 kg greater in mean BW when compared to group 2 heifers at weaning, yearling, and prebreeding, respectfully (P= 0.14, P= 0.08, P < 0.01, respectfully). In conclusion, these data indicate that coat shedding score was inversely correlated to physical and ultrasound measurements taken at weaning, yearling and prebreeding. Producers selecting replacement heifers may be able to utilize coat shedding score as another characteristics to assess desirable replacement heifers.
Keywords:
Replacement heifer, Beef cattle, Coat Shedding