Effects of temperament on pregnancy rates to fixed-timed AI in Bos indicus beef cows

• Published in: Livestock science 2011-12, Vol.142 (1-3), p.108-113
• Main Authors: Cooke, R.F., Bohnert, D.W., Meneghetti, M., Losi, T.C., Vasconcelos, J.L.M.
• Format: Article
• Language: English
• Subjects: Bos indicus; Reproduction; Temperament
• ISSN: 1871-1413; 1878-0490
• DOI: 10.1016/j.livsci.2011.06.024

The objective of the present experiment was to assess the effects of temperament on pregnancy rates to fixed-time AI (FTAI) in Bos indicus beef cows. A total of 761 multiparous lactating Nelore cows, originated from 4 different commercial cow–calf ranches, were evaluated for BCS and temperament at the time of FTAI (day 0). Temperament was assessed by chute score and exit velocity. Further, individual exit score was calculated by dividing exit velocity results into quintiles and assigning cows with a score from 1 to 5 (exit score: 1=slowest cows; 5=fastest cow). Temperament scores were calculated by averaging cow chute score and exit score. Cows were also classified for temperament type according to temperament score (≤3=adequate temperament, >3=excitable temperament). Pregnancy status was verified by detecting a viable conceptus with rectal ultrasonography approximately 40days after FTAI. Chute score, exit velocity, and temperament score were not correlated to BCS (P>0.31). Hence, BCS did not differ (P=0.30) according to temperament type (4.13 vs. 4.09 for cows with excitable and adequate temperament, respectively; SEM=0.070). Pregnancy rates to FTAI tended to be negatively affected by temperament score (P=0.08), whereas the probability of cows becoming pregnant to FTAI was negatively associated with temperament score (linear effect, P