Introducing heifers in to the main herd

Introducing fresh calved dairy heifers in to the main herd following afternoon milking could improve welfare by reducing aggression levels.

That was the conclusion of Queens University’s Alastair Boyle, who recognised heifer release in to the main herd could have negative effects on welfare and productivity.

Speaking at the British Society of Animal Science Conference, Belfast, he said; “Integration of dairy heifers in to the main herd post-calving can be stressful because heifers often have low social status when entering the herd and thus are subjected to increased levels of bullying,” he said.

The study looked at whether time of day when heifers were introduced in to the herd could impact on welfare and performance. “We introduced heifers in to the main herd at 24-36 hours post-calving and they were either introduced after morning milking (between 6-8am) or after afternoon milking (4pm-6pm).” Cow behaviour and performance was then recorded.

“We found that introducing heifers to the resident group post afternoon milking reduced levels of aggression and also increased levels of social cohesion thus could be said to improve welfare. The reason for this could be cows are naturally less socially active in the evening. Heifers in the morning received more aggressive treatment from resident cows,” he explained.