Denholm K S, Hunnam J C, Cuttance E L, McDougall S
a Anexa FVC , 1126 Gordonton Road, Gordonton , New Zealand.
b Cognosco , 25 Moorhouse Street, Morrinsville , New Zealand.
N Z Vet J. 2017 Sep;65(5):257-263. doi: 10.1080/00480169.2017.1342575. Epub 2017 Jul 3.
To describe colostrum quality in spring-calving dairy herds in New Zealand, in terms of Brix, pH and total and coliform bacterial counts and to investigate associations between farm management practices and these measures of colostrum quality.
In June 2015, commercial dairy farms (n=105), located in North and South Islands of New Zealand, were visited shortly after the first cows had calved, and when approximately 50% and 80% of the herd had calved (early, middle and late visits). One litre of pooled colostrum that was being fed to newborn calves was collected at each visit and used to determine Brix, pH, total bacterial and coliform counts. A survey of calf management practices was conducted with the herd manager or calf rearer after the final visit.
Of 298 pooled colostrum samples tested 29/298 (9.7%) had Brix >22%. Brix was higher on farms where calves were picked up twice daily compared with once daily (18.2 (95% CI=16.5-19.9)% vs. 15.9% (95% CI=15.2-16.6)%; p=0.012), and was lower where first milking colostrum was combined with colostrum obtained at later milkings (15.0 (95% CI=13.9-16.1)%) compared with where it was not (16.9 (95% CI=16.3-17.6)%; p=0.002). Vaccination of all cows against calf diarrhoeal pathogens was associated with increased Brix compared with no vaccination (18.1 (95% CI=16.6-19.6)% vs. 16.3 (95% CI=15.6-17.0)%; p=0.033). Mean pH of samples tested decreased from 5.97 (95% CI=5.84-6.09) to 5.58 (95% CI=5.45-5.71) for early and late-season visits, respectively (p<0.001). Of 268 samples tested, 23 (8.6%) had bacterial counts below the recommended threshold of 1.00×10 cfu/mL. Mean bacterial counts increased from 2.75 (95% CI=1.80-3.70)×10 to 4.99 (95% CI=3.95-6.03)×10 cfu/mL for early and late-season visits, respectively (p<0.001). Of 259 samples tested, 23 (8.9%) had coliform counts below the recommended threshold of 1.00×10 cfu/mL.
On a large majority of dairy farms included in this study the pooled colostrum fed to newborn calves had sub-optimal Brix and excessive bacterial counts. Farm-level risk factors such as twice daily pick up of calves from the paddocks, herd vaccination and feeding pooled colostrum that did not combine colostrum obtained at later milkings with first milking colostrum were associated with colostrum quality measures.
根据乳密度、pH值、总细菌数和大肠菌群数来描述新西兰春季产犊奶牛群的初乳质量，并调查农场管理实践与这些初乳质量指标之间的关联。
2015年6月，在新西兰北岛和南岛的首批奶牛产犊后不久，以及当牛群约50%和80%产犊时（早期、中期和晚期访问），对105个商业奶牛场进行了访问。每次访问时收集一升喂给新生犊牛的混合初乳，用于测定乳密度、pH值、总细菌数和大肠菌群数。在最后一次访问后，与牛群管理者或犊牛饲养员进行了犊牛管理实践的调查。
在检测的298份混合初乳样本中，29/298（9.7%）的乳密度>22%。与每天接犊一次的农场相比，每天接犊两次的农场乳密度更高（18.2（95%CI=16.5-19.9）%对15.9%（95%CI=15.2-16.6）%；p=0.012），与未将首次挤奶的初乳与后期挤奶获得的初乳混合的农场相比，将首次挤奶的初乳与后期挤奶获得的初乳混合的农场乳密度更低（15.0（95%CI=13.9-16.1）%对16.9（95%CI=16.3-17.6）%；p=0.002）。与未接种疫苗相比，所有奶牛接种预防犊牛腹泻病原体的疫苗与乳密度增加相关（18.1（95%CI=16.6-19.6）%对16.3（95%CI=15.6-17.0）%；p=0.033）。早期和晚期访问时，检测样本的平均pH值分别从5.97（95%CI=5.84-6.09）降至5.58（95%CI=5.45-5.71）（p<0.001）。在检测的268份样本中，23份（8.6%）的细菌数低于推荐阈值1.00×10 cfu/mL。早期和晚期访问时，平均细菌数分别从2.75（95%CI=1.80-3.70）×10升至4.99（95%CI=3.95-6.03）×10 cfu/mL（p<0.001）。在检测的259份样本中，23份（8.9%）的大肠菌群数低于推荐阈值1.00×10 cfu/mL。
在本研究纳入的大多数奶牛场中，喂给新生犊牛的混合初乳乳密度不理想且细菌数过多。农场层面的风险因素，如每天两次从牧场接犊、牛群接种疫苗以及喂给不将后期挤奶获得的初乳与首次挤奶初乳混合的混合初乳，与初乳质量指标相关。
