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Transgenerational paternal influence on temperament and growth performance of crossbred beef calves
The objective was to evaluate the transgenerational paternal influence on temperament characteristics and growth performance in a group of crossbred calves sired by bulls that did or did not experience prenatal stress (PNS). These sires were derived from a purebred Brahman population in which dams were assigned to receive 1 of 2 treatments, control (CTRL; n=42) or PNS (n=43). Cows in the PNS group were subjected to 2 h of transportation at 60, 80, 100, 120, and 140 d of gestation (Littlejohn et al., 2016). From this group, 3 sexually mature control and 3 PNS Brahman bulls were mated with mature cows (20 cows per bull) to produce a second generation of calves. These crossbred calves were evaluated for temperament utilizing pen score (PS; 1=calm and 5=excitable), exit velocity (EV; m/sec) and temperament score (TEMP; PS+EV/2) at weaning (d 0; adjusted 205 d), d 28 and d 56. At these same time points body weights were recorded. All data were analyzed using Mixed Models Procedures of SAS. Treatment of sire and sex of calf were included as fixed effects. Male calves had greater birth weights compared to females (P< 0.001). Steers had greater adjusted 205 d, d 28 and 56 BW (P <0.005) compared with heifers. Calves from PNS sires had greater (P<0.001) adjusted 205 d BW compared to calves from CTRL sires but this did not carry through d 28 or 56. Male calves from PNS sires had greater (P<0.001) adjusted 205 d BW, male calves from CTRL sires and female calves from PNS sires were intermediate and female calves from CTRL sires had the lowest adjusted 205 d BW. Male and female calves from CTRL sires had the greatest PS (P<0.002), EV (P<0.05) and TEMP (P<0.002) scores at weaning compared to male and female calves from PNS sires. Individual sire influenced (P<0.05) all measures of temperament and BW. Weaning TEMP score was highly (P<0.001) correlated to TEMP scores at d 28 and 56 (0.66 and 0.68, respectively). Calves from CTRL sires had greater TEMP scores at weaning; however, by d56 these differences had diminished. Calves from PNS sires had greater adjusted 205 d BW; however, these differences in BW at weaning, d 28 or 56 were not apparent where adjustments for age of dam and sex of calf were not included. Temperament measures in PNS were lower than for CTRL calves.
Keywords: beef calves, temperament, transgenerational