Temperament of Nelore growing-steers receiving supplementation in grazing system: Performance, ultrasound measures, feeding behavior, and serum parameters

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2020-11-01

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A study was performed to evaluate the temperament of beef cattle on grazing system regarding performance, ultrasound measures, feeding behavior, and physiological parameters. Twenty growing animals [Nelore; non-castrated males; 220 ± 33 kg initial body weight (BW); 10 ± 1 months of age] on rotational stocking system (Urochloa brizantha cv. Xaraés) were used. Individual temperament scores were calculated by averaging animal chute score and exit velocity score [adequate (ADQ) ≤ 3; or excitable (EXC) > 3] at the beginning of the trial period (d 0). At the same day, animals were ranked by temperament and BW, and assigned to receive (n = 10) or not (control = CON; n = 10) a supplementation (SUP). Body condition score (BCS), BW, hip height (HH), and ultrasound evaluations (ribeye area - uLMA; backfat thickness - uBFT) were recorded on d 0 and 84. Difference between BW (d 84 and 0) were used to determine the average daily gain (ADG). Blood samples were collected at 0, 28, 56, and 84 d and analyzed for serum cortisol, insulin, and haptoglobin. Feeding behavior data (time of grazing, rumination, resting, and drinking water) were obtained by all-animals scan sampling (4 d; 24-h per day). No interactions of temperament with supplementation were detected for performance. ADQ animals had a greater initial and final BW (P ≤ 0.032), and ADG (P = 0.031) than EXC animals. No differences were found for the other growth performance variables studied regarding temperament classification. SUP group had greater values for final BW (P< 0.001), ADG (P< 0.001), initial and final uLMA (P ≤ 0.002), and higher final HH (P = 0.007) than CON group. Interactions of temperament with period (P< 0.01) were observed for grazing, rumination, and resting behaviors. ADQ animals showed higher probability of grazing, ruminating, and resting events during some periods of the day, whereas EXC animals had higher probability of ruminating events and resting events in other periods. No effects of temperament were identified for serum parameters (P ≥ 0.157), however, a tendency for diet effect was detected (P = 0.066) for cortisol concentration, for which SUP animals showed higher values than CON animals. In conclusion, growth performance and feeding behavior are impacted in Nelore growing cattle by temperament and supplementation. Therefore, animal temperament is a characteristic that must be considered in beef cattle produced in grazing systems.

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Livestock Science, v. 241.