INRAE, Oniris, BIOEPAR, 44300, Nantes, France.
INRAE, Oniris, BIOEPAR, 44300, Nantes, France.
Prev Vet Med. 2021 May;190:105321. doi: 10.1016/j.prevetmed.2021.105321. Epub 2021 Mar 4.
Rearing dairy calves with nurse cows has been increasingly adopted by French farmers especially in organic farming and is characterized by a fostering of two to four calves during the first month of life by an unmilked lactating cow. This type of rearing remains poorly documented regarding its impact on calf health, such as cryptosporidiosis. The objectives of our study were to describe practices related to rearing dairy calves with nurse cows and to evaluate the prevalence, intensity and risk factors for Cryptosporidium infection in calf neonates. Between January and September 2019, the rearing practices of calves were described in 20 organic French farms and faeces were sampled once from 611 animals aged between 5 and 21 days. Cryptosporidium oocyst shedding was identified by modified Ziehl-Neelsen technique and scored semi-quantitatively (score 0-4). The risk of excretion (score 0 versus 1-4) was analysed using multivariate logistic regression models. This cow-calf rearing system usually consisted of a first phase with the dam, followed by an optional phase of artificial milk feeding (calves being fed with whole milk of the farm) and a final phase of fostering by a nurse cow. Each nurse was suckled from one to five calves of close age with a fostering age of 8 days on average. The oocyst shedding prevalence was 40.2 % and similar to classically reared calves, but the intensity of shedding and the prevalence of diarrhoea appeared to be lower. The identified six risk factors for oocyst shedding were: born in the last two thirds of the birth order, born between January and July versus August and September, calf with its dam in the barn versus on pasture, having an artificial milk feeding phase versus being with the dam only, and contact between peer calves and notably the presence of an oocyst excretory calf fostered by the same nurse. These results emphasize the role of the environment for the direct and indirect contamination, particularly that related to the accumulation of oocysts from previous or peer calves facilitating the faecal-oral route of transmission. This highlights the crucial role of the premises used intensively during the winter and spring months with higher densities of calves in the barn compared to outdoor situations promoted by this rearing.
法国农民越来越多地采用用奶牛哺育奶牛小牛的方式，特别是在有机农业中，这种方式的特点是在生命的第一个月里，由未挤奶的哺乳期奶牛哺育两到四只小牛。关于这种饲养方式对小牛健康的影响，例如隐孢子虫病，其相关记录很少。我们研究的目的是描述与用奶牛哺育奶牛小牛有关的做法，并评估新生小牛隐孢子虫感染的流行率、强度和危险因素。2019 年 1 月至 9 月期间，在 20 个法国有机农场中描述了小牛的饲养方式，并对年龄在 5 至 21 天之间的 611 只动物的粪便进行了一次采样。采用改良的齐尔-尼尔森技术识别隐孢子虫卵囊脱落，并进行半定量评分（评分 0-4）。采用多变量逻辑回归模型分析排泄风险（评分 0 与 1-4）。这种奶牛-小牛饲养系统通常包括第一阶段与母牛在一起，然后是可选的人工喂养阶段（小牛用农场的全脂牛奶喂养），最后是由奶牛保姆哺育阶段。每头奶牛保姆哺育年龄相近的 1 至 5 头小牛，平均哺育年龄为 8 天。卵囊脱落的流行率为 40.2%，与传统饲养的小牛相似，但脱落的强度和腹泻的流行率似乎较低。确定的 6 个卵囊脱落危险因素为：出生顺序在后三分之二，1 月至 7 月出生与 8 月至 9 月出生，小牛与母牛在畜棚中而非牧场上，有一个人工喂养阶段与只有母牛在一起，以及同龄小牛之间的接触，特别是同一头奶牛保姆哺育的一个卵囊排泄小牛。这些结果强调了环境对直接和间接污染的作用，特别是与先前或同龄小牛的卵囊积累有关，这有助于粪口传播途径。这突出了在冬季和春季几个月中密集使用牛舍的关键作用，与户外情况相比，牛舍中的小牛密度更高，这种饲养方式促进了这种情况的发生。
