Abstract
In Europe, dairy cows are commonly kept in loose-housing systems under outdoor climatic conditions. Seasonal variations of the climate thus directly affect performance, behaviour, health and consequently welfare of the animals. Still, it is unknown whether results of welfare assessments are influenced by the time of the year they are conducted. Therefore, the aim of this study was to assess 20 dairy cattle farms in four different seasons using the Welfare Quality protocol (WQP). Additionally, barns climate was recorded continuously by data loggers. The daily average temperature-humidity-index was calculated following the formula of National Research Council [winter: 50±5; spring: 51±7; summer: 70±5; autumn: 55±4]. A linear mixed model and pairwise Pearson chi-squared tests were performed to estimate differences between the four seasons. In terms of animal-based indicators, the prevalence of mild lameness was higher in spring (32%) and summer (35%) compared with winter (25%) [P<0.05], whereas diarrhoea was determined more often in winter (21%), summer (22%) and autumn (19%) than in spring (12%) [P<0.05]. Mild integument alterations were rated lower in winter (39%) and spring (36%) than in autumn (47%) [P<0.05]. Mastitis was found less often in winter (21%) and spring (26%) than in autumn (47%) [P<0.05]. The emotional state – evaluated with the qualitative behaviour assessment approach – was scored (range 0 to 100 pts) lower in summer (65 pts) compared with winter (79 pts) and spring (74 pts) [P<0.05]. In contrast, the percentage of lean cows was higher in winter (7%) than in summer (5%) and autumn (3%) [P<0.05]. For the remaining welfare indicators (e.g. nasal discharge, coughing, agonistic behaviour) no seasonal effects were observed [P>0.05]. The WQP overall classification (‘enhanced’ 44%; ‘acceptable’ 56%) also did not differ between seasons [P>0.05]. In conclusion, the results demonstrate the independence of the WQP overall classification results from seasonal effects, while single indicators are related. Consequently, the time of year welfare is assessed should be considered whenever studies are compared for single indicators.