Cameron M, Keefe G P, Roy J-P, Stryhn H, Dohoo I R, McKenna S L
Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada C1A 4P3.
Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada C1A 4P3.
J Dairy Sci. 2015 Apr;98(4):2427-36. doi: 10.3168/jds.2014-8876. Epub 2015 Jan 31.
Compared with blanket dry cow therapy (DCT), the selective antimicrobial treatment of cows based upon on-farm culture results has the potential to reduce the amount of antimicrobials used in dairy production. The objective of the current study was to determine the effect of a Petrifilm (3M Canada, London, Ontario) on-farm culture-based selective DCT program on milk yield and somatic cell count (SCC) in the following lactation. A total of 729 low-SCC (<200,000 cells/mL) cows from 16 commercial dairy herds with a low bulk tank SCC (<250,000 cells/mL) were randomly assigned to receive either blanket DCT or Petrifilm-based selective DCT. Cows belonging to the blanket DCT group were infused with a commercial DCT product and an internal teat sealant (ITS) at drying off. Using composite milk samples collected on the day before drying off, cows in the selective DCT group were treated at drying off based on the results obtained by the Petrifilm on-farm culture system with DCT and ITS (Petrifilm culture positive) or ITS alone (Petrifilm culture negative). Milk test-day records for the following lactation were obtained from Dairy Herd Improvement for all cows enrolled in the trial. Repeated measures linear mixed models were used to assess the effect of study group (blanket or selective DCT) on test-day milk production and natural logarithm of SCC over the first 180 d of the subsequent lactation. According to the final multivariable models, when low-SCC cows were selectively treated with DCT at drying off based on results obtained using the Petrifilm on-farm culture system, no effect on milk production (least squares means for blanket DCT = 39.3 kg vs. selective DCT = 39.0 kg) or natural logarithm of SCC (least squares means for blanket DCT = 3.95 vs. selective DCT = 3.97) was observed in the subsequent lactation when compared with cows receiving blanket DCT. The results of this study indicate that selective DCT based on results obtained by the Petrifilm on-farm culture system enabled a reduction in the use of DCT without negatively affecting milk production and milk quality.
与传统干奶疗法（DCT）相比，基于农场培养结果对奶牛进行选择性抗菌治疗有可能减少乳制品生产中抗菌药物的使用量。本研究的目的是确定基于Petrifilm（3M加拿大公司，安大略省伦敦市）农场培养的选择性DCT程序对下一泌乳期牛奶产量和体细胞计数（SCC）的影响。来自16个商业奶牛场且储奶罐SCC较低（<250,000个细胞/毫升）的729头低SCC（<200,000个细胞/毫升）奶牛被随机分配接受传统DCT或基于Petrifilm的选择性DCT。传统DCT组的奶牛在干奶时注射一种商业DCT产品和一种乳头内密封剂（ITS）。利用干奶前一天采集的混合奶样，选择性DCT组的奶牛在干奶时根据Petrifilm农场培养系统的结果进行治疗，结果为Petrifilm培养阳性的奶牛接受DCT和ITS治疗，培养阴性的奶牛仅接受ITS治疗。从参与试验的所有奶牛的奶牛群改良记录中获取下一泌乳期的牛奶检测日记录。采用重复测量线性混合模型评估研究组（传统或选择性DCT）对下一泌乳期前180天检测日牛奶产量和SCC自然对数的影响。根据最终的多变量模型，当根据Petrifilm农场培养系统的结果在干奶时对低SCC奶牛进行选择性DCT治疗时，与接受传统DCT的奶牛相比，在下一泌乳期未观察到对牛奶产量（传统DCT的最小二乘均值 = 39.3千克 vs. 选择性DCT = 39.0千克）或SCC自然对数（传统DCT的最小二乘均值 = 3.95 vs. 选择性DCT = 3.97）有影响。本研究结果表明，基于Petrifilm农场培养系统结果的选择性DCT能够减少DCT的使用，且不会对牛奶产量和质量产生负面影响
