Population Medicine, University of Guelph, Guelph, ON, Canada N1G 2W1.
Population Medicine, University of Guelph, Guelph, ON, Canada N1G 2W1.
J Dairy Sci. 2022 Feb;105(2):1402-1417. doi: 10.3168/jds.2021-20551. Epub 2021 Nov 17.
This randomized controlled trial investigated the effects of temporarily reducing milking frequency (MF) on the resolution of ketosis and milk production in dairy cows in early lactation. To detect ketosis [blood β-hydroxybutyrate (BHB) ≥1.2 mmol/L], Holstein cows were screened daily from 3 to 16 d in milk using a cow-side meter. Cows diagnosed with ketosis (n = 104) were randomly assigned to twice-daily milking (TDM) or reduced to once-daily milking (ODM) for 2 wk, then returned to twice-daily milking. Both treatment groups received a 5-d treatment of an oral propylene glycol drench (PG; 300 g) beginning on the afternoon of the diagnosis; cows received additional 5-d PG treatments if they had a ketotic test result (blood BHB ≥1.2 mmol/L) at least 4 d after finishing the first PG treatment. Blood BHB tests were conducted for the first 3 d after ketosis diagnosis, and then once every 3 d for 21 d of trial (DOT). Milk and milk component data were collected weekly for 15 wk following trial enrollment. The ODM group showed rapidly and markedly decreased blood BHB concentrations (primiparous cows: 1 DOT, 0.92 ODM vs. 1.22 TDM, 15 DOT, 0.55 vs. 0.81 mmol/L; multiparous cows: 1 DOT, 1.01 vs. 1.40, 15 DOT, 0.78 vs. 1.65 mmol/L). In addition, a logistic regression model indicated that ODM cows were less likely to have blood BHB concentrations ≥1.2 mmol/L [primiparous cows: 3 DOT: ODM 1% (95% confidence interval: 0-10%) vs. TDM 43% (30-58%), 15 DOT ODM 0% (0-0.2%) vs. TDM 22% (13-36%); multiparous cows: 3 DOT: ODM 33% (24-44%) vs. TDM 59% (48-69%), 15 DOT ODM 20.9% (13-31%) vs. TDM 64% (53-74%)]. The proportion of ODM cows that required additional treatments of PG were substantially lower than the TDM group (ODM: 39%; TDM: 64%) than the TDM cows during the initial 21-d period. However, during the 2-wk treatment period, cows in the ODM group produced 26% less milk and 25% less energy-corrected milk than the TDM cows. During wk 3 to 15, when all cows were milked twice daily, ODM cows produced less milk (-14%) and energy-corrected milk (-12%) compared with the TDM group. Milk protein percentage was greater, and milk fat percentage and linear score tended to be greater in the ODM group over 15 wk. In conclusion, a 2-wk reduction of MF in ketotic cows from twice to once daily with treatment with PG resolved ketosis and decreased blood BHB concentrations more effectively than treating TDM cows with PG alone. However, the 2-wk MF reduction had immediate and long-term (up to 13 wk after cessation of MF reduction) negative effects on milk production.
本随机对照试验研究了暂时减少挤奶频率（MF）对泌乳早期奶牛酮病缓解和产奶量的影响。为了检测酮病[血液 β-羟丁酸（BHB）≥1.2mmol/L]，在产后 3 至 16 天内，使用奶牛侧的仪器每天对荷斯坦奶牛进行筛查。诊断出患有酮病的奶牛（n=104）被随机分配到每天两次挤奶（TDM）或减少到每天一次挤奶（ODM），持续 2 周，然后恢复到每天两次挤奶。两组治疗组均在诊断后的下午开始接受 5 天的口服丙二醇灌胃（PG；300g）治疗；如果在第一次 PG 治疗结束后至少 4 天内出现酮病检测结果（血液 BHB≥1.2mmol/L），则给予另外 5 天的 PG 治疗。在诊断为酮病后的前 3 天内进行血液 BHB 检测，然后在试验的 21 天内每 3 天检测一次（DOT）。在试验登记后的 15 周内，每周收集一次产奶量和乳成分数据。ODM 组的血液 BHB 浓度迅速显著下降（初产奶牛：1 DOT，0.92 ODM 与 1.22 TDM，15 DOT，0.55 与 0.81mmol/L；经产奶牛：1 DOT，1.01 与 1.40，15 DOT，0.78 与 1.65mmol/L）。此外，逻辑回归模型表明，ODM 奶牛血液 BHB 浓度≥1.2mmol/L 的可能性较小[初产奶牛：3 DOT：ODM 1%（95%置信区间：0-10%）与 TDM 43%（30-58%），15 DOT ODM 0%（0-0.2%）与 TDM 22%（13-36%）；经产奶牛：3 DOT：ODM 33%（24-44%）与 TDM 59%（48-69%），15 DOT ODM 20.9%（13-31%）与 TDM 64%（53-74%）]。在最初的 21 天内，ODM 奶牛需要额外治疗 PG 的比例明显低于 TDM 组（ODM：39%；TDM：64%）。然而，在 2 周的治疗期间，ODM 组的奶牛比 TDM 组的奶牛产奶量减少了 26%，产能量校正奶减少了 25%。在第 3 周至第 15 周，当所有奶牛每天都挤两次奶时，ODM 组的奶牛产奶量（-14%）和能量校正奶（-12%）均低于 TDM 组。在 15 周内，ODM 组的乳蛋白百分比较高，乳脂百分比和线性评分趋势较高。综上所述，在酮病奶牛中，2 周内将 MF 从每天两次减少到一次，并用 PG 治疗，比单独用 PG 治疗 TDM 奶牛更有效地解决了酮病并降低了血液 BHB 浓度。然而，2 周的 MF 减少对产奶量有即时和长期（停止 MF 减少后长达 13 周）的负面影响。
