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干奶期内乳头内密封剂的留存情况及其在降低产犊时临床和亚临床乳腺炎方面的功效。

Retention of internal teat sealants over the dry period and their efficacy in reducing clinical and subclinical mastitis at calving.

作者信息

Bates A J, King C, Dhar M, Fitzpatrick C, Laven R A

机构信息

Vetlife Scientific Ltd., Vetlife Temuka, 1, Waitohi-Temuka Road, Temuka, 7920, New Zealand.

Norbrook New Zealand Ltd., KPMG Centre, 18 Viaduct Harbour Avenue, Maritime Square Auckland, Auckland, 1010, New Zealand.

出版信息

J Dairy Sci. 2022 Jun;105(6):5449-5461. doi: 10.3168/jds.2021-21585. Epub 2022 Apr 2.

Abstract

Internal teat sealants (ITS) reduce the risk of new intramammary infections over the dry period by forming a physical barrier to pathogen ingress. As the first and last 2 wk of the dry period are high-risk periods for new infections, maintaining an effective barrier in this period is a key requirement. Few studies have systematically examined sealant retention and none have done so under New Zealand pastoral conditions, where cows frequently move to separate grazing for dry periods, typically 80 to 90 d long. This multi-herd study was a split-udder equivalence trial comparing 2 ITS formulations for retention and efficacy in preventing periparturient clinical and subclinical mastitis. Both ITS contained 65% (2.6 g) bismuth salts, which contribute to the barrier within the teat canal, emulsified in ≤1.4 g of mineral oil. However, one ITS additionally contained <10% amorphous silica. At dry-off, treatment was randomly allocated to diagonal teat-pairs within 409 cows on 4 farms. All cows met industry best practice criteria for ITS treatment alone. The study unit was quarter within cow and farm. Outcomes included clinical mastitis (CM) incidence for the last 7 d of the dry period and first 42 d of lactation, subclinical mastitis (SCM) incidence 96 h after calving, and quantity of residual after centrifuging 50 mL of colostrum collected from each quarter within 24 h of calving. Proportional outcomes were analyzed using Bayesian mixed models with a binomial distribution and logit link function, whereas the quantity of residual was analyzed using Bayesian finite mixture models and cluster bootstrapping. We set a region of probable equivalence (ROPE) of ±2.5% between proportions and ±0.2 g for residual weight. Records were available for 1,596 quarters (399 cows). We detected no meaningful difference in incidence of CM or SCM attributable to differences in sealant: the model predicted treatment differences of 0.00 with a 95% highest density interval (HDI) of ±1.00%. Across all cows and farms, the marginal difference in the percentage of quarters with CM was 0.11% (95% HDI: -2.11 to 2.49%), and for SCM 0.00 (95% HDI: -1.98 to 1.94%). Including the quantity of residual recovered at calving did not improve fit or predictive ability of the models predicting CM or SCM, and the coefficient spanned the null value. The distribution of the weight of material recovered at calving was multi-modal; for 25% of quarters, more residual was recovered than inserted. When the residual weight was less than or equal to the median residual weight (2.06 g; range: 0.19-6.03 g), there was a ≥90% probability that any treatment difference in residual was ≤0.2 g. When the residual weight was between the median and 75th percentile (4.40 g; 95% HDI: 4.00 to 4.75 g), there was no clear difference in residual between products. Above the 75th percentile, there was a 90% probability that the residual from quarters differed by product type (difference = 0.36 g, 90% HDI: 0.20 to 0.54 g). In conclusion, both products had equivalent efficacy for SCM and CM. As the quantity of residual increased, the difference in residual weight recovered increased but this may represent increases in debris rather than indicating a more effective barrier.

摘要

乳房内密封剂(ITS)通过形成一道阻止病原体侵入的物理屏障,降低了干奶期新的乳房内感染风险。由于干奶期的前两周和后两周是新感染的高危期,在此期间维持有效的屏障是一项关键要求。很少有研究系统地研究密封剂的留存情况,在新西兰的牧场条件下则尚无此类研究,在那里奶牛在干奶期通常会转移到单独的牧场放牧,干奶期一般为80至90天。这项多牧场研究是一项双乳等效性试验,比较了两种ITS配方在预防围产期临床和亚临床乳腺炎方面的留存情况和效果。两种ITS均含有65%(2.6克)的铋盐,其有助于在乳腺管内形成屏障,并在≤1.4克的矿物油中乳化。然而,一种ITS还含有<10%的无定形二氧化硅。在干奶时,对4个牧场的409头奶牛的对角乳头进行随机分配处理。所有奶牛均符合单独进行ITS处理的行业最佳实践标准。研究单位是奶牛和牧场内的乳头区。结果包括干奶期最后7天和泌乳期前42天的临床乳腺炎(CM)发病率、产犊后96小时的亚临床乳腺炎(SCM)发病率,以及在产犊后24小时内从每个乳头区收集的50毫升初乳离心后的残留量。比例性结果使用具有二项分布和logit链接函数的贝叶斯混合模型进行分析,而残留量则使用贝叶斯有限混合模型和聚类自举法进行分析。我们设定了比例之间±2.5%以及残留重量±0.2克的可能等效区域(ROPE)。共有1596个乳头区(399头奶牛)有记录。我们未检测到因密封剂差异导致的CM或SCM发病率有显著差异:模型预测的处理差异为0.00,95%最高密度区间(HDI)为±1.00%。在所有奶牛和牧场中,发生CM的乳头区百分比的边际差异为0.11%(95% HDI:-2.11至2.49%),SCM为0.00(95% HDI:-1.98至1.94%)。纳入产犊时回收的残留量并未改善预测CM或SCM的模型的拟合度或预测能力,且系数跨越零值。产犊时回收的物质重量分布是多峰的;25%的乳头区回收的残留量超过插入量。当残留重量小于或等于中位数残留重量(2.06克;范围:0.19 - 6.03克)时,残留量的任何处理差异≤0.2克的概率≥90%。当残留重量介于中位数和第75百分位数之间(4.40克;95% HDI:4.00至4.75克)时,产品之间的残留量无明显差异。高于第75百分位数时,不同产品乳头区的残留量有90%的概率存在差异(差异 = 0.36克,90% HDI:0.20至0.54克)。总之,两种产品在预防SCM和CM方面疗效相当。随着残留量增加,回收的残留重量差异增大,但这可能代表碎片增加,而非表明屏障更有效。

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