一项关于减轻热应激对环境条件以及生长、饲料效率和断奶前雌性荷斯坦小牛代谢物浓度影响的随机试验。
A randomized trial on the effects of heat stress abatement on environmental conditions and growth, feed efficiency, and concentration of metabolites of pre-weaned female Holstein calves.
机构信息
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville 32610, USA.
Dairy Design Engineers, Gainesville, FL 32608, USA.
出版信息
Prev Vet Med. 2023 Apr;213:105863. doi: 10.1016/j.prevetmed.2023.105863. Epub 2023 Jan 31.
Heat abatement strategies for pre-weaned calves are seldom adopted. Our objectives were to determine the effects of adding fans to barns on environmental conditions and growth, feed efficiency, concentration of metabolites and health of pre-weaned female Holstein calves. Calves born from July 15th to 30th of 2019 were eligible for enrollment. At birth (d 0), calves were assigned randomly to: SH (n = 125) - hutch under a barn with no cooling, SHF (n = 101) - hutch under a barn cooled through fans. Body weight (BW) and wither-height were measured at birth and d 68. Calves were evaluated thrice weekly (0700-1000 h) using the Calf Health Scoring Chart (UW-Madison). A sub-sample of hutches (SH = 26, SHF = 25) was evaluated for air velocity and temperature at 1000 and 1600 h thrice weekly and calves housed in these hutches were evaluated for rectal temperature (RT) at 1600 h and respiratory rate (RR) at 1000 and 1600 h. Calves were fed a liquid diet twice a day (d 2-18 = 5.56 L/d; d 19-49 = 7.58 L/d; d 50-56 = 3.84 L/d; d 57-63 = 1.64 L/d) and starter ad libitum starting on d 14. A sub-sample of calves (SH = 56, SHF = 44) had intakes of liquid feed and starter measured daily, BW and wither-height measured weekly from birth to d 68, and blood sampled on d 1, 14, 28, 42, 49, 52, 56, 58, 63 and 65 for the measurement of fatty acids, β-hydroxybutyrate, and glucose concentrations. The SHF treatment increased air velocity by 0.8 m/sec and reduced air temperature by 0.3 ºC. The SHF treatment reduced RT (38.70 ± 0.03 vs. 38.78 ± 0.02 °C) and the percentage of calves with hyperthermia (RT ≥ 39.2 °C; 20.6 ± 1.9 vs. 30.2 ± 2.0%) at 1000 h. Treatment did not affect feed efficiency (SH = 0.53 ± 0.01, SHF = 0.53 ± 0.01 g of BW gained/g of dry matter intake), nor did it affect BW (SH = 81.6 ± 0.7, SHF = 82.9 ± 0.8 kg) and wither-height (SH = 89.5 ± 0.3, SHF = 90.1 ± 0.3 cm) on d 68. Concentrations of metabolites were not affected by treatment. Cooling the environment through fans reduced RT and the risk of hyperthermia at 1000 h but it did not affect performance of pre-weaned Holstein calves.
很少有研究采用降温措施来降低断奶前犊牛的环境温度。本研究旨在评估在牛舍内安装风机对环境条件、生长性能、饲料效率、代谢物浓度和健康的影响。本研究选择 2019 年 7 月 15 日至 30 日出生的荷斯坦奶牛作为研究对象，犊牛在出生时（d0）随机分为两组：SH 组（n=125），在没有冷却设备的牛舍中饲养；SHF 组（n=101），在安装有风机的牛舍中饲养。在出生时和 68 日龄时分别测量犊牛体重和肩高。每周三次（0700-1000h）使用威斯康星大学麦迪逊分校的犊牛健康评分表（Calf Health Scoring Chart，CHS）对犊牛进行评估。每周三次（0700-1000h），在 1000h 和 1600h 时测量 26 个 SH 组和 25 个 SHF 组牛舍内空气速度和温度，在 1600h 时测量犊牛直肠温度（RT），在 1000h 和 1600h 时测量呼吸频率（RR）。犊牛从出生至 18 日龄（d2-18）时，每天饲喂 2 次液体饲料（5.56L/d），19-49 日龄（d19-49）时，每天饲喂 2 次液体饲料（7.58L/d），50-56 日龄（d50-56）时，每天饲喂 1 次液体饲料（3.84L/d），1 至 63 日龄（d1-63）时，每天饲喂 1 次液体饲料（1.64L/d），从 14 日龄开始自由采食开食料。56 个 SH 组和 44 个 SHF 组的部分犊牛每天记录液体饲料和开食料的摄入量，每周测量一次体重和肩高，从出生至 68 日龄。分别在第 1、14、28、42、49、52、56、58、63 和 65 日龄时采血，用于测量脂肪酸、β-羟丁酸和葡萄糖浓度。与 SH 组相比，SHF 组的空气速度增加了 0.8m/sec，空气温度降低了 0.3 ºC。SHF 组降低了 1000h 时的 RT（38.70±0.03 与 38.78±0.02 ºC）和发热犊牛的比例（RT ≥ 39.2 ºC；20.6±1.9 与 30.2±2.0%）。处理对饲料效率（SH=0.53±0.01，SHF=0.53±0.01g/kg 体重增长/g 干物质采食量）、BW（SH=81.6±0.7kg，SHF=82.9±0.8kg）和 68 日龄肩高（SH=89.5±0.3cm，SHF=90.1±0.3cm）均没有影响。代谢物浓度不受处理的影响。通过风机降低环境温度可以降低 1000h 时的 RT 和发热风险，但不会影响断奶前荷斯坦犊牛的性能。
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