School of Veterinary Science, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand.
School of Veterinary Science, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand.
J Dairy Sci. 2020 Dec;103(12):11820-11832. doi: 10.3168/jds.2020-18743. Epub 2020 Oct 23.
Our objective was to identify practical indicators of calf dehydration that could be used in an industry context. Eleven healthy 4-d-old commercial dairy calves were fed 2 L of mixed colostrum, then deprived of food and water for 24 h. Total body water was determined in the fed state using the deuterium dilution method. Body weight, along with a range of behavioral and physiological variables, was recorded 1 h after feeding, then at 90-min intervals through to 24 h. Blood samples were collected at every second sampling to assess changes in plasma hemoglobin, hematocrit, and osmolality. Linear mixed-effects models were used to explore associations between hydration status (% body water) and outcome variables. All calves remained bright and alert with good suckling reflexes throughout the 24-h period. After 24 h, total body water had decreased by an average of 8.4% (standard error 1.18), consistent with mild to moderate dehydration. Skin tent return time, capillary refill time, and detectable enophthalmos were associated with hydration status. Calves with skin tent return times of 3 s or longer were 4.4 percentage points less hydrated than those with return times of less than 3 s. Similarly, a capillary refill time of 3 s or longer was associated with a 4.3 percentage point reduction in hydration compared with refill times of less than 3 s. Calves with detectable enophthalmos (≥1 mm) were 3.5 percentage points less hydrated than those without enophthalmos. The skin tent, capillary refill, and enophthalmos tests are all relatively simple to perform and, although requiring the calf to be briefly restrained, can easily be performed by a single operator. The outcome of these tests was relatively consistent, in that calves above the threshold in any test were 3.5 to 4.5% less hydrated than calves below the threshold. As such, these tests may be of practical utility to identify calves with mild to moderate dehydration in an industry setting.
我们的目标是确定可在行业背景下使用的 calves 脱水的实用指标。11 头健康的 4 日龄商业奶牛犊牛接受了 2 L 的混合初乳，然后被剥夺食物和水 24 h。在喂养状态下使用氘稀释法确定总体液量。在喂养后 1 小时记录体重，以及一系列行为和生理变量，然后每隔 90 分钟记录一次，直到 24 h。每隔一次采样采集血液样本，以评估血浆血红蛋白、血细胞比容和渗透压的变化。使用线性混合效应模型探索水合状态（%体重水）与结局变量之间的关联。在 24 h 期间，所有犊牛保持明亮警觉，吮乳反射良好。24 h 后，总体液量平均下降 8.4%（标准误差 1.18），符合轻度至中度脱水。皮肤帐篷返回时间、毛细血管再充盈时间和可检测的眼球内陷与水合状态有关。皮肤帐篷返回时间为 3 s 或更长的犊牛比返回时间小于 3 s 的犊牛少 4.4 个百分点。同样，毛细血管再充盈时间为 3 s 或更长与再充盈时间小于 3 s 的犊牛相比，水合作用减少了 4.3 个百分点。可检测到眼球内陷（≥1 mm）的犊牛比没有眼球内陷的犊牛少 3.5 个百分点。皮肤帐篷、毛细血管再充盈和眼球内陷测试都相对简单，虽然需要将犊牛短暂地约束，但可以由单个操作人员轻松进行。这些测试的结果相对一致，即在任何测试中超过阈值的犊牛比低于阈值的犊牛少 3.5%至 4.5%。因此，这些测试可能在行业环境中识别轻度至中度脱水的犊牛具有实际应用价值。
