São Paulo State University, Department of Animal Production, Botucatu 18168-000, Brazil.
Anim Reprod Sci. 2011 Sep;127(3-4):140-7. doi: 10.1016/j.anireprosci.2011.07.012. Epub 2011 Jul 30.
The objective of this study was to evaluate the associations among milk production, rectal temperature, and pregnancy maintenance in lactating recipient dairy cows. Data were collected during an 11-mo period from 463 Holstein cows (203 primiparous and 260 multiparous) assigned to a fixed-time embryo transfer (ET) protocol. Only cows detected with a visible corpus luteum immediately prior to ET were used. Rectal temperatures were collected from all cows on the same day of ET. Milk production at ET was calculated by averaging individual daily milk production during the 7d preceding ET. Pregnancy diagnosis was performed by transrectal ultrasonography 21d after ET. Cows were ranked and assigned to groups according to median milk production (median=35kg/d; HPROD=above median; LPROD=below median) and rectal temperature (≤39.0°C=LTEMP; >39.0°C=HTEMP). A milk production×temperature group interaction was detected (P=0.04) for pregnancy analysis because HTEMP cows ranked as LPROD were 3.1 time more likely to maintain pregnancy compared with HTEMP cows ranked as HPROD (P=0.03). Milk production did not affect (P=0.55) odds of pregnancy maintenance within LTEMP cows, however, and no differences in odds of pregnancy maintenance were detected between HTEMP and LTEMP within milk production groups (P>0.11). Within HTEMP cows, increased milk production decreased the probability of pregnancy maintenance linearly, whereas within LTEMP cows, increased milk production increased the probability of pregnancy maintenance linearly. Within HPROD, increased rectal temperature decreased the probability of pregnancy maintenance linearly, whereas within LPROD cows, no associations between rectal temperatures and probability of cows to maintain pregnancy were detected. In summary, high-producing dairy cows with rectal temperatures below 39.0°C did not experience reduced pregnancy maintenance to ET compared to cohorts with reduced milk production.
本研究旨在评估泌乳受体奶牛的产奶量、直肠温度与妊娠维持之间的关系。在一项为期 11 个月的时间里，从 463 头荷斯坦奶牛（203 头初产牛和 260 头经产牛）中收集数据，这些奶牛被分配到一个定时胚胎移植（ET）方案中。只有在 ET 前立即检测到可见黄体的奶牛才被使用。所有奶牛在 ET 当天采集直肠温度。ET 时的产奶量通过在 ET 前 7 天内平均个体每日产奶量来计算。通过 ET 后 21 天的直肠超声检查进行妊娠诊断。根据中位产奶量（中位数=35kg/d；HPROD=高于中位数；LPROD=低于中位数）和直肠温度（≤39.0°C=LTEMP；>39.0°C=HTEMP）对奶牛进行排名和分组。由于 HTEMP 奶牛中排名为 LPROD 的奶牛维持妊娠的可能性比排名为 HPROD 的 HTEMP 奶牛高 3.1 倍（P=0.03），因此在妊娠分析中检测到产奶量×温度组间的相互作用（P=0.04）。然而，在 LTEMP 奶牛中，产奶量不影响（P=0.55）维持妊娠的几率，并且在产奶量组内 HTEMP 和 LTEMP 之间也未检测到维持妊娠的几率存在差异（P>0.11）。在 HTEMP 奶牛中，产奶量增加呈线性降低妊娠维持的可能性，而在 LTEMP 奶牛中，产奶量增加呈线性增加妊娠维持的可能性。在 HPROD 中，直肠温度升高呈线性降低妊娠维持的可能性，而在 LPROD 奶牛中，直肠温度与奶牛维持妊娠的几率之间没有关联。综上所述，直肠温度低于 39.0°C 的高产奶牛与产奶量降低的奶牛相比，ET 后的妊娠维持率没有降低。
