Kasimanickam V R, Abdel Aziz R L, Williams H M, Kasimanickam R K
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, USA.
Department of Theriogenology, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef, Egypt.
Reprod Domest Anim. 2018 Apr;53(2):484-494. doi: 10.1111/rda.13135. Epub 2018 Jan 19.
Two experiments were conducted to determine (i) factors influencing calf temperament at weaning, (ii) association between heifer-calf temperament at weaning and temperament at breeding and (iii) effect of heifer-calf temperament on pregnancy rate per artificial insemination (P/AI). In experiment 1, beef cows and their calves (n = 285) from three farms were used. Sire docility estimated progeny difference (EPD) score, birth type (normal or assisted), calf gender, calf behaviour (during 1st 4 weeks) and calf health status (until weaning) were recorded. Cows and calves were assigned a temperament score (0-calm; 1-excitable), and all cows were given a body condition score (BCS, 1-9; 1-emaciated; 9-obese) at weaning. Calf's illness (p < .05), low sire docility EPD score (p < .05), altered gait (p < .05), altered resting behaviour (p < .01), reduced/no play behaviour (p < .05) and cow excitable temperament (p < .001) increased calf excitable temperament at weaning. In experiment 2, replacement heifer-calves (n = 758) from 12 farms were assigned a temperament score at weaning and later at breeding. Blood from 40 calves at weaning and 31 heifers at initiation of synchronization (same animals) was collected by coccygeal venipuncture for determination of circulating cortisol and substance P concentrations. Heifers were assigned a BCS and reproductive tract score (RTS, 1-5; 1-immature, acyclic; 5-mature, cyclic), synchronized for fixed time AI, observed for oestrus and were artificially inseminated. Cortisol concentrations were increased in excitable heifer-calves compared to calm heifer-calves at weaning (p < .05), and substance P was increased in excitable compared to calm females both at weaning and breeding (p < .05). Low sire EPD docility score (p < .01), heifer-calf excitable temperament at weaning increased excitable temperament at breeding (p < .01). Controlling for BCS categories (p < .01), oestrous expression (p < .0001) and temperament at breeding by oestrous expression (p < .05), the calf's excitable temperament at weaning (p < .001) reduced P/AI (Calm, 62.7 (244/389) vs. Excitable, 53.4% (197/369); p < .01). In conclusion, selection of docile cows and sires with greater docility EPD score should be given consideration to reduce calf excitement. Temperament in beef female can be detected earlier in their life and could be used as a tool in the selection process and to improve their performances.
（i）断奶时影响犊牛性情的因素；（ii）断奶时小母牛犊性情与配种时性情之间的关联；以及（iii）小母牛犊性情对每次人工授精受胎率（P/AI）的影响。在试验1中，使用了来自三个农场的肉牛母牛及其犊牛（n = 285）。记录了父本温顺性估计后裔差异（EPD）评分、出生类型（正常或助产）、犊牛性别、犊牛行为（在最初4周内）以及犊牛健康状况（直至断奶）。给母牛和犊牛评定了一个性情评分（0 - 温顺；1 - 易兴奋），并且在断奶时给所有母牛评定了体况评分（BCS，1 - 9；1 - 消瘦；9 - 肥胖）。犊牛患病（p < 0.05）、父本温顺性EPD评分低（p < 0.05）、步态改变（p < 0.05）、休息行为改变（p < 0.01）、玩耍行为减少/无玩耍行为（p < 0.05）以及母牛易兴奋的性情（p < 0.001）会增加断奶时犊牛易兴奋的性情。在试验2中，来自12个农场的后备小母牛犊（n = 758）在断奶时和之后配种时被评定了性情评分。在断奶时从40头犊牛以及在同步发情开始时从31头小母牛（同一批动物）采集尾静脉血，用于测定循环皮质醇和P物质浓度。给小母牛评定了BCS和生殖道评分（RTS，1 - 5；1 - 未成熟、无发情周期；5 - 成熟、有发情周期），进行定时人工授精同步发情处理，观察发情情况并进行人工授精。与断奶时温顺的小母牛犊相比，易兴奋的小母牛犊皮质醇浓度升高（p < 0.05），并且在断奶和配种时，与温顺的小母牛相比，易兴奋的小母牛P物质浓度升高（p < 0.05）。父本EPD温顺性评分低（p < 0.01）、断奶时小母牛犊易兴奋的性情会增加配种时易兴奋的性情（p < （此处原文似乎有误，推测应为p < 0.01））。在控制BCS类别（p < 0.01）、发情表现（p < 0.0001）以及发情表现对配种时性情的影响（p < 0.05）后，断奶时犊牛易兴奋的性情（p < 0.001）降低了P/AI（温顺，62.7%（244/389）对易兴奋，53.4%（197/369）；p < 0.01）。总之，应考虑选择温顺的母牛和具有更高温顺性EPD评分的父本以减少犊牛兴奋。肉牛母畜的性情在其生命早期即可检测到，可作为选择过程中的一种工具并用于提高其生产性能。
