Effects of temperament on growth, plasma cortisol concentrations and puberty attainment in Nelore beef heifers

Abstract

Excitable temperament disrupts physiological events required for reproductive development in cattle, but no research has investigated the impacts of temperament on growth and puberty attainment in Bos indicus females. Hence, this experiment evaluated the effects of temperament on growth, plasma cortisol concentrations and puberty attainment in B. indicus heifers. A total of 170 Nelore heifers, weaned 4 months before the beginning of this experiment (days 0 to 91), were managed in two groups of 82 and 88 heifers each (mean ± SE; initial BW=238±2 kg, initial age=369±1 days across groups). Heifer temperament was evaluated via exit velocity on day 0. Individual exit score was calculated within each group by dividing exit velocity into quintiles and assigning heifers with a score from 1 to 5 (1=slowest; 5=fastest heifer). Heifers were classified according to exit score as adequate (ADQ, n=96; exit score⩽3) or excitable temperament (EXC, n=74; exit score>3). Heifer BW, body condition score (BCS) and blood samples were obtained on days 0, 31, 60 and 91. Heifer exit velocity and score were recorded again on days 31, 60 and 91. Ovarian transrectal ultrasonography was performed on days 0 and 10, 31 and 41, 60 and 70, 81 and 91 for puberty evaluation. Heifer was declared pubertal at the first 10-day interval in which a corpus luteum was detected. Exit velocity and exit score obtained on day 0 were correlated (r⩾0.64, P<0.01) with evaluations on days 31, 60 and 91. During the experiment, ADQ had greater (P<0.01) mean BCS and BW gain, and less (P<0.01) mean plasma cortisol concentration compared with EXC heifers. Temperament × time interactions were detected (P<0.01) for exit velocity and exit score, which were always greater (P<0.01) in EXC v. ADQ heifers. A temperament × time interaction was also detected (P=0.03) for puberty attainment, which was delayed in EXC v. ADQ heifers. At the end of the experiment, a greater (P<0.01) proportion of ADQ were pubertal compared with EXC heifers. In summary, B. indicus heifers classified as EXC had reduced growth, increased plasma cortisol concentrations and hindered puberty attainment compared to ADQ heifers. Moreover, exit velocity may serve as temperament selection criteria to optimize development of B. indicus replacement heifers.

The Effect of Stress on Reproduction and Reproductive Technologies in Beef Cattle—A Review

“…Aggressive temperament in heifers can lead to lower pregnancy rate and delay puberty or even prevent its onset [ 50 , 102 , 103 , 104 ]. Conversely, quieter temperament has been shown to lead to higher rates of estrus and pregnancy, shorter time to pregnancy and lower rate of pregnancy loss [ 20 , 99 , 101 ].…”

Genetic control of temperament traits across species: association of autism spectrum disorder risk genes with cattle temperament

“…In humans, temperament traits include personality and behavior phenotypes such as extraversion, openness and neuroticism, and are genetically correlated with several psychiatric disorders, both common (such as major depression and anxiety disorders) and less common (such as schizophrenia and autism) [1][2][3][4][5][6]. In cattle, and other livestock species, temperament traits are of welfare and commercial importance because more docile animals can grow faster, are easier to transport and feed, and can have superior meat quality [7][8][9][10][11][12]. Moreover, reactive animals can also endanger the safety of their contemporaries and also their human handlers.…”

Association between temperament related traits and single nucleotide polymorphisms in the serotonin and oxytocin systems in Merino sheep

“…In sheep, the phenotype and the genetic heritability of temperament traits have been assessed using behavioral tests like an arena test and an isolation box test 7‐9 . Similarly, the temperament of bovines has been assessed for decades using behavioral tests such as the open field arena test, a flight speed test, an exit velocity test, and a crush score test 4,10,11 . However, the classic behavior tests, like the arena test, isolation box test, and flight speed test, are time and labor consuming, and difficult to carry out in young animals 12 .…”