Onderwerp scriptie

Behavioural effects of regrouping in relation to fresh feed delivery in lactating Holstein cows - Anne-Marieke Smid

This study examined if lactating dairy cows and heifers regrouped at a time of fresh feed delivery differed in their behaviour and milk production from cows and heifers regrouped at a time not associated with fresh feed delivery. The experiment included 2 treatments: early regrouped animals that were individually introduced into a stable group at 03:00 h, and late regrouped animals that were individually introduced into a stable group after morning milking, coinciding with access to fresh feed.

Regrouping of cows in dairy farming is the introduction of one or several cows into a social stable group of conspecifics. This study examined if lactating dairy cows and heifers regrouped at a time of fresh feed delivery differed in their behaviour and milk production from cows and heifers regrouped at a time not associated with fresh feed delivery. The experiment included 2 treatments: early regrouped animals (8 cows; 8 heifers) that were individually introduced into a stable group (11 animals/pen) at 03:00 h and late regrouped animals (8 cows; 8 heifers) that were individually introduced into a stable group after morning milking, coinciding with access to fresh feed. For 3 days, video recordings continuously monitored feeding and lying behaviour, agonistic interactions and behavioural synchronicity. Data loggers were used to quantify the number of standing bouts and daily lying time; milk production was automatically recorded at each milking.

No large differences in daily feeding or lying time, number of standing bouts or behavioural synchronicity existed between the treatments or between cows and heifers. Social interactions at the feed bunk were primarily initiated by cows as opposed to heifers; interactions around the lying stalls were primarily initiated by early regrouped cows and late regrouped heifers. Early regrouped animals showed a lower drop in milk production compared to late regrouped animals. Cows, especially late regrouped cows, spent the most time feeding during the first 3 hours after fresh feed delivery; lying time showed a more inconsistent pattern during this time. Cows seemed to cope better with regrouping than heifers. As cows are often larger and higher in rank than heifers, they might be better able to access resources, particularly during times of social instability. Late regrouped cows, however, seemed to cope best with regrouping.

Consistency of management procedures might be important for animals. Therefore, regrouping at times not associated with routine management procedures may be more stressful for cows than for heifers that have less experience with regrouping. In conclusion, regrouping at a time that is not associated with fresh feed delivery might be preferred for heifers, but not for cows.

Student: AMC Smid

Supervisors: dr ir E Bokkers (APS)

prof dr M von Keyserlingk (Univ. of British Columbia)

prof dr D Weary (Univ. of British Columbia)

36 Ects