School of Agriculture and Food Sciences, Animal Science Group, The University of Queensland, Gatton, QLD, 4343, Australia.
School of Environmental and Rural Science, Animal Science, University of New England, Armidale, NSW, 2350, Australia.
Int J Biometeorol. 2022 Feb;66(2):275-288. doi: 10.1007/s00484-021-02169-y. Epub 2021 Jul 15.
The objective of this study was to evaluate the influence of supplementing lactating dairy cows with Saccharomyces cerevisiae on milk production and composition, cow behavior, and physiological responses during summer. Twenty primiparous cows were used and two treatments were imposed: (1) control (CON); and (2) probiotic supplementation (PRO; S. cerevisiae, providing 10 colony forming units (CFU) per day). Rumen temperature (T, °C) and pH were obtained via rumen boluses. Rumen temperatures were obtained from all cows (n = 20) at 10-min intervals and ruminal pH were obtained from five cow pairs (n = 10) at 10-min intervals. Ambient temperature (T; °C), relative humidity (RH; %), wind speed (WS; m/s), and solar radiation (SR; W/m) were recorded at 10-min intervals. The temperature humidity index (THI) was calculated using T and RH. Cows were milked twice daily. Milk fat (%), protein (%), lactose (%), and somatic cell count (SCC, '000) were evaluated on 16 occasions. Cows were observed three times (0800 h; 1200 h; and 1400 h) daily for panting score (PS); respiration rate (RR); posture (standing/lying); shade utilization; and cow activity (eating/drinking/ruminating). Individual PS were used to calculate a mean panting score (MPS) for CON and PRO treatments for each observation. S. cerevisiae did not influence milk yield (P = 0.87), fat (P = 0.82), protein (P = 0.26) or SCC (P = 0.19), although there was a tendency for PRO cows to have higher lactose (P = 0.06). Probiotics did not influence the proportion of cows utilizing shade (P = 0.42); standing (P = 0.41); ruminating (P = 0.72); or drinking (P = 0.40). All cows exhibited an increase in RR (> 24 bpm) at 1200 h and RR showed a steady increase as THI increased (P < 0.0001), regardless of treatment (P = 0.96). Both CON (35.8%) and PRO (40.2%) exhibited an increase in MPS as THI increased from thermoneutral (THI ≤ 74) to very hot (THI ≥ 84.1; P < 0.001). However, PRO cows had lower (2.19 ± 0.09; P < 0.0001) MPS compared with CON (2.54 ± 0.22) cows when THI was categorized as very hot (THI ≥ 84.1). Rumen pH were not influenced by treatment (P = 0.38), however T of PRO cows were 0.2 °C lower across days (P < 0.0001) and hours (P < 0.0001). These results suggest that supplementing cows with S. cerevisiae may support thermoregulation via decreased T and MPS; however, further studies are required.
本研究的目的是评估在夏季给泌乳奶牛补充酿酒酵母对产奶量和组成、奶牛行为以及生理反应的影响。使用了 20 头初产奶牛，并实施了两种处理：（1）对照（CON）；和（2）益生菌补充（PRO；提供每天 10 个菌落形成单位（CFU）的酿酒酵母）。通过瘤胃球囊获得瘤胃温度（T，°C）和 pH 值。所有奶牛（n = 20）每隔 10 分钟获得一次瘤胃温度，5 对奶牛（n = 10）每隔 10 分钟获得一次瘤胃 pH 值。每隔 10 分钟记录环境温度（T；°C）、相对湿度（RH；%）、风速（WS；m/s）和太阳辐射（SR；W/m）。使用 T 和 RH 计算温度湿度指数（THI）。奶牛每天挤奶两次。每隔 16 次评估牛奶中的脂肪（%）、蛋白质（%）、乳糖（%）和体细胞计数（SCC，“000”）。每天观察奶牛三次（0800 h；1200 h；和 1400 h）以评估喘气评分（PS）；呼吸率（RR）；姿势（站立/躺下）；遮荫利用；和奶牛活动（进食/饮水/反刍）。使用个体 PS 计算 CON 和 PRO 处理的每个观察的平均喘气评分（MPS）。酿酒酵母对产奶量（P = 0.87）、脂肪（P = 0.82）、蛋白质（P = 0.26）或 SCC（P = 0.19）没有影响，尽管 PRO 奶牛的乳糖更高（P = 0.06）。益生菌对利用遮荫的奶牛比例（P = 0.42）；站立（P = 0.41）；反刍（P = 0.72）；或饮水（P = 0.40）没有影响。所有奶牛在 1200 h 时 RR（> 24 bpm）增加，并且随着 THI 的增加，RR 呈稳定增加（P < 0.0001），与处理无关（P = 0.96）。当 THI 从热中性（THI ≤ 74）增加到非常热（THI ≥ 84.1 时，CON（35.8%）和 PRO（40.2%）都表现出 MPS 的增加（P < 0.001）。然而，当 THI 被归类为非常热（THI ≥ 84.1）时，PRO 奶牛的 MPS 比 CON（2.54 ± 0.22）奶牛低（2.19 ± 0.09；P < 0.0001）。处理对瘤胃 pH 值没有影响（P = 0.38），但 PRO 奶牛的 T 每天（P < 0.0001）和每小时（P < 0.0001）都低 0.2°C。这些结果表明，给奶牛补充酿酒酵母可能通过降低 T 和 MPS 来支持体温调节；然而，还需要进一步的研究。
