Effects of temperament on body parameters, ovarian structures and inflammatory response in grazing Nellore cows following fixed-time artificial insemination

Abstract

This study evaluated the associations of temperament with body weight (BW) and body condition score (BCS) change, ovarian structures, and inflammatory response in grazing Nellore cows assigned to a fixed-time artificial insemination protocol. Forty multiparous cows were kept on pasture and offered free-choice access to mineral/vitamin supplementation and fixed-time artificial insemination on d 0. Individual temperament scores (1-5) were assessed in the squeeze chute on d -30, where 1 are animals extremely calm and 5 extremely excitable. Cows with a chute score ≤ 3 were classified as ``calm'', and > 3 as ``excitable''. The BW and BCS were evaluated on days -30, 0 and 30, ovarian structures on days 0 and 14, and blood samples collected on days -30, -11, 0, 7, 14, 21 and 30. Excitable animals tended to have less (P = 0.09) BCS and lose more (P = 0.09) BCS from d -30 to 0. Temperament did not affect (P ≥ 0.12) BW and BW change. Excitable animals tended (P ≤ 0.10) to have smaller dominant follicles, corpus luteum (CL) diameters and CL volumes. Temperament did not affect (P ≥ 0.14) plasma concentrations of haptoglobin and ceruloplasmin, but excitable animals had less (P = 0.04) plasma concentrations of progesterone on days 7 and 14. Thus, excitable cows had less plasma progesterone concentrations and tended to have a greater decrease in BCS and had smaller dominant follicles and CL size.