Impacts of temperament on reproductive performance of Bos indicus and B. taurus beef females

Abstract Text:

Temperament is defined as the fear-related behavioral responses of cattle when exposed to human handling. Our group evaluates cattle temperament using: 1) chute score; 1 to 5 scale that increases according to excitable behavior during restraint in a squeeze chute, 2) exit velocity; speed of an animal exiting the squeeze chute, 3) exit score; dividing cattle according to exit velocity into quintiles using a 1 to 5 scale (1 = cattle in the slowest quintile; 5 = cattle in the fastest quintile), and 4) temperament score; average of chute and exit scores. Subsequently, cattle are assigned a temperament type; adequate temperament (ADQ; temperament score ≤ 3) or excitable temperament (EXC; temperament score > 3). To assess the impacts of temperament on reproductive efficiency in beef production systems, our group associated these evaluation criteria with puberty attainment and pregnancy rates in Bos taurus and B. indicus-influenced females. Cattle classified as EXC had greater plasma cortisol vs. ADQ cattle during handling, independent of breed type (B. indicus × B. taurus, P < 0.01; B. taurus, P < 0.01; B. indicus, P = 0.04) or age (cows, P < 0.01; heifers, P < 0.01). In regards to reproductive variables, B. taurus and B. indicus × B. taurus EXC heifers reached puberty at older ages (P < 0.05) compared with ADQ cohorts. Cows classified as EXC had reduced annual pregnancy rates vs. ADQ cows across breed types (B. taurus, P = 0.03; B. indicus × B. taurus, P = 0.04; B. indicus, P = 0.05). Moreover, B. taurus EXC cows also had decreased calving rate (P = 0.04), weaning rate (P = 0.09), and kg of calf weaned/cow exposed to breeding (P = 0.08) vs. ADQ cohorts. Our group also reported that acclimating B. indicus × B. taurus or B. taurus heifers to human handling improved temperament (P ≤ 0.02), reduced plasma cortisol (P < 0.01), and hastened puberty attainment (P ≤ 0.02). Hence, strategies to improve herd temperament, including selection for this trait and acclimation of young animals to human handling, are imperative for optimal reproductive efficiency of beef operations based on B. taurus and B. indicus influenced cattle.

Keywords: beef cattle, reproduction, temperament