Changes in behaviour of dairy cows with clinical mastitis

• Cows with clinical mastitis in early lactation exhibited sickness behaviour.
• Before diagnosis of mastitis cows decreased feed intake and competitive behaviour.
• Feed intake and competitive behaviour increased in the days after cows were treated.

Behaviour is an important tool for recognizing illness in animals. One of the most common diseases in dairy cattle is clinical mastitis. Evidence suggests that cows with this disease show sickness behaviours, but little is known about the progression of behavioural changes before and after the disease becomes clinical. The aims of this study were to determine changes in feeding and competitive behaviour at the feed bunk of dairy cows before the diagnosis of clinical mastitis and determine the effect of intramammary antibiotic treatment on behaviour. Dry matter intake, feeding time, number of visits to the feeder, rate of feed intake, number of replacements occurring at the feeder (when one cow displaced a feeding cow and took her position at the feed bin) and the percent of intake during peak feeding time were measured daily in eight cows diagnosed with clinical mastitis in one quarter of the udder. Clinical mastitis was diagnosed based on daily rectal body temperature as well as condition of the foremilk and udder assessed by the milker at each milking from calving until 30 days in milk. Starting on the day of diagnosis, cows received an intramammary antibiotic twice daily for three consecutive days. During the 5 days period before diagnosis, cows decreased feed intake by 1.2 kg/d (SE = 0.2, P < 0.001) but showed no other changes in feeding behaviour during this time. The frequency of competitive replacements at the feeder (slope = −2.3 no./d, SE = 1.0, P = 0.04) and the percentage of intake at peak feeding time (slope = −1.8%, SE = 0.6, P = 0.008) were lower compared to day of diagnosis. Following treatment, cows immediately increased feed intake, feeding time and competitive replacements at the feeder. These results show that cows with naturally occurring clinical mastitis exhibit signs of sickness behaviour in the days before diagnosis, and that these behaviours rapidly recover in the days after treatment.