Flighty cows are likely to respond to stress, e.g. change of environment, by producing less milk. This and other intriguing points have been noted during a study of dairy cow temperament at AgResearch.
In view are changes to cow management strategies.
The aspect of the human-animal relationship on which a recent AgResearch study focused was dairy cow temperament.
Understanding cow temperament is important, particularly during the period when heifers are being inducted into the milking herd. At this time, heifers that are fearful could potentially injure themselves or the stress response associated with high levels of fear could affect milk production leading to economic losses.
The aims of this study were: 1) to use behavioural measures to assess cow temperament in the paddock and in the milking parlour, and, 2) determine the relationship between cow temperament and milk production parameters, such as milk let-down.
Cow temperament was initially assessed in the paddock. An unfamiliar person would approach an individual cow and the point at which the cow moved away from the approaching person was recorded and was considered to be the cow’s ‘flight distance’. Cows with a large flight distance were designated ‘flighty’; cows that had a short flight distance were designated ‘calm’.
From a herd of 80 cows, the 20 flightiest and 20 calmest cows were selected. More behavioural tests were then performed on the cows individually to evaluate temperament in more detail, including how they performed in response to restraint and how quickly they exited the restraint when released.
Once all the cows were designated flighty or calm, they were milked normally in a rotary shed over a five day period and behavioural and physiological measures of stress and milk production were recorded.
Cows were then milked in an environment novel for them – a herringbone shed – and the same behavioural and physiological measures were recorded to see if their temperament would affect the way they would react to a novel/stressful situation.
Flighty cows appeared to have higher stress levels than calm cows prior to milking as shown by higher heart rate and blood cortisol concentrations.
Cortisol concentrations are commonly used to assess stress in animals in response to a range of different stressors.
However, flighty cows did not perform differently from calm cows in the rotary shed as measured by the amount of assistance they needed to move onto the platform or the amount of kicking they did while cups were being put on.
Milk production did differ significantly between flighty and calm cows though. Milk yield tended to be greater and milking duration was longer in calm than flighty cows throughout the study.
Milk let-down also differed between flighty and calm cows. Milk flow rate initially increased at a similar rate between flighty and calm cows, then plateaued in calm cows before decreasing gradually until milk let-down ceased.
Milk flow rate in flighty cows, on the other hand, dipped after 30 seconds before increasing again.
Overall, there was no difference in the average milk flow rate between flighty and calm cows, but maximal flow rate was greater in flighty cows.
More interesting, when cows were milked in an unfamiliar milking shed, milk flow rate was normal in calm cows but markedly reduced in flighty cows.
These results suggest a relationship between cow temperament and milk production parameters and that milk production is more likely to be negatively affected in flighty cows in response to a stressor, such as a change of environment.
Mhairi Sutherland is a scientist at AgResearch, New Zealand.