Animal Welfare Program, Faculty of Land and Food Systems, The University of British Columbia, Vancouver, V6T 1Z4, Canada.
Laboratório de Etologia Aplicada e Bem-Estar Animal, Departamento de Zootecnia e Desenvolvimento Rural, Universidade Federal de Santa Catarina, Florianópolis, 88034-001, Brazil.
J Dairy Sci. 2019 Jul;102(7):6373-6382. doi: 10.3168/jds.2018-15717. Epub 2019 May 10.
Lameness is a serious welfare issue for dairy cows. To date, the majority of studies have focused on its effect on health and behavior at the herd level. The objectives of this study were to identify (1) between-cow and (2) within-cow changes in lying behavior associated with consistent and changing lameness status in grazing dairy cows. Previous studies of lying behavior in grazing dairy cows have not considered the effect of precipitation, so a third aim was to determine the effect of precipitation on lying behavior. A total of 252 dairy cows from 6 pasture-based farms in southern Brazil were gait scored weekly to assess lameness using a 5-point scale [1-5, numerical rating score (NRS)] for 4 consecutive weeks. Cows were considered to have consistent lameness if they were scored as lame (NRS ≥3) on each of the 4 visits and considered to have a changing lameness status if scored as being nonlame (NRS <3) on at least 1 of the 4 visits. Cows classified as having a changing lameness status were further classified as developed, recovered, or inconsistent. Lying behavior (daily lying time, mean lying bout duration, and daily number of lying bouts) was recorded continuously for 3 wk using leg-mounted accelerometers. Cow-level variables included parity, days in milk, and body condition score. Regional precipitation and temperature were recorded hourly. Because only 1 primiparous cow was identified as lame at each of the 4 visits, the between-cow analysis of lameness was run on multiparous cows only. The overall prevalence of clinical lameness on the first visit was 39%, with development and recovery rates of 16 and 10% over the 4 visits, respectively. The between-cow effect of consistent lameness status on daily lying time and number of lying bouts was dependent on precipitation; consistently lame cows had reduced lying time and lying bouts on days with rain compared with days without rain. There was no within-cow effect of changing lameness status on any of the lying behaviors. Precipitation was associated with decreased daily lying time, increased mean lying bout duration, and decreased daily number of lying bouts. The results of this research provide the first evidence that the effect of consistent lameness status on lying behavior is associated with rainfall in grazing dairy cows. Future work measuring lying behavior of grazing dairy cows should include precipitation as a covariate.
跛行是奶牛的严重福利问题。迄今为止，大多数研究都集中在其对群体健康和行为的影响上。本研究的目的是确定（1）在放牧奶牛中，与持续和变化的跛行状态相关的个体间和（2）个体内卧姿变化。先前对放牧奶牛卧姿行为的研究并未考虑降水的影响，因此第三个目标是确定降水对卧姿行为的影响。来自巴西南部 6 个牧场的 252 头奶牛每周进行步态评分，使用 5 分制（1-5，数字评分）[1-5，数字评分（NRS）]连续 4 周评估跛行。如果奶牛在 4 次就诊中的每次就诊中均被评为跛行（NRS≥3），则认为其跛行状态持续；如果奶牛在至少 1 次就诊中被评为非跛行（NRS<3），则认为其跛行状态变化。将被归类为跛行状态变化的奶牛进一步分为发展、恢复或不一致。使用腿部安装的加速度计连续记录 3 周的卧姿行为（每日卧姿时间、平均卧姿持续时间和每日卧姿次数）。牛水平变量包括胎次、产奶天数和身体状况评分。每小时记录区域降水和温度。由于在 4 次就诊中的每次就诊中仅识别出 1 头初产奶牛跛行，因此仅对经产奶牛进行跛行的个体间分析。第一次就诊时临床跛行的总体患病率为 39%，在 4 次就诊中，发展和恢复率分别为 16%和 10%。持续跛行状态对每日卧姿时间和卧姿次数的个体间影响取决于降水；与无雨日相比，持续跛行的奶牛在雨天的卧姿时间和卧姿次数减少。跛行状态变化的个体内影响与任何卧姿行为均无关。降水与每日卧姿时间减少、平均卧姿持续时间增加和每日卧姿次数减少有关。本研究的结果首次提供了证据表明，持续跛行状态对卧姿行为的影响与放牧奶牛中的降雨有关。未来测量放牧奶牛卧姿行为的工作应将降水作为协变量。
