Núcleo de Estudos em Etologia e Bem-estar Animal (NEBEA), Universidade Federal de Juiz de Fora (UFJF), Juiz de Fora, Minas Gerais, Brazil.
Departamento de Zootecnia e Desenvolvimento Rural, Universidade Federal de Santa Catarina (UFSC), Florianópolis, Brazil.
J Therm Biol. 2021 Jan;95:102793. doi: 10.1016/j.jtherbio.2020.102793. Epub 2020 Nov 28.
Factors related to the thermal physiology and activity of Zebu animals close to calving are still unknown. The aims of this study were 1) to describe the pattern of reticulo-rumen temperature and activity variation in nulliparous Gyr heifers close to calving, and 2) to evaluate the predictive potential of these traits for calving in Gyr heifers. Forty pregnant Gyr heifers that had calved between August and December 2017 at the Getúlio Vargas Experimental Station, Empresa de Pesquisa Agropecuária de Minas Gerais (Epamig), Brazil, were used. The animals received a rumen bolus to monitor reticulo-rumen temperature (Trr) and activity (Act) at intervals of 10 min. Mixed linear models were used. A decrease in Trr and an increase in Act were observed on the days preceding calving. Differences in Trr and Act were more evident during the final 21 and 11 h previous to calving compared to 14 days before calving, measured at the same time of day. There was a decrease of about 0.20 °C in Trr at the time of calving when compared to baseline (14 days before calving measured at the same time of day). Environmental variables, such as temperature and air humidity, as well as biological factors such as circadian rhythm, may influence the interpretation of the data. In conclusion, variations exist in the Trr and Act of Gyr heifers in the hours before calving, which is preceded by a decrease in Trr and an increase in Act. Particularities in the thermal physiology of Zebu cattle must be considered when prediction devices previously validated only for European breeds are used.
与接近分娩的瘤牛动物的热生理学和活动相关的因素尚不清楚。本研究的目的是：1）描述接近分娩的初产吉拉荷斯坦奶牛瘤胃温度和活动变化的模式，2）评估这些性状对吉拉荷斯坦奶牛分娩的预测潜力。使用了 2017 年 8 月至 12 月在巴西米纳斯吉拉斯州农业研究公司 Getúlio Vargas 实验站分娩的 40 头怀孕的吉拉荷斯坦奶牛。给动物投喂瘤胃测热仪胶囊，以每 10 分钟监测一次瘤胃温度（Trr）和活动（Act）。使用混合线性模型。在接近分娩前的日子里，观察到 Trr 下降和 Act 增加。与在接近分娩前 14 天相比，在分娩前最后 21 和 11 小时测量时，Trr 和 Act 的差异更为明显，测量时间相同。与基线（在接近分娩前 14 天，在相同时间测量）相比，Trr 在分娩时下降了约 0.20°C。环境变量，如温度和空气湿度，以及生物因素，如昼夜节律，可能会影响对数据的解释。总之，在接近分娩的前几个小时，吉拉荷斯坦奶牛的 Trr 和 Act 存在变化，之前 Trr 下降，Act 增加。在使用以前仅针对欧洲品种验证过的预测装置时，必须考虑瘤牛的热生理学特殊性。
