Ko och kalv tillsammans i mjölkproduktion - fältförsök på två ekologiska gårdar

Summary

The purpose of this study was to investigate how calves in organic production gain weight when they are allowed to suckle during the first 3 months of life. Furthermore, the cows' milk production and cell count were studied during and after the suckling period.
The test calves were kept with the cows during the daytime and separated at night. During the summer they were kept outdoors and during the winter inside the barn. The test group was compared with a control group where the calves were separated from the cow a few days after birth and then fed manually or via an automatic feeder. The control calves were fed 9-10 liters of milk 3 times a day. The mothers of the control calves were used as a control group for the cows included in the study. A total of 38 cow-calf pairs were included on 2 farms, including 18 pairs in the trial group and 20 pairs in the control group. All calves were weighed, or the chest circumference was measured once a week throughout the suckling period, a total of 13 weeks. The chest circumference data was then converted to a weight in kg through an equation. Data from the milking unit on milk production and cell count were collected from all milking sessions during lactation day 0 to 130.
The test calves gained an average of 9.49 ± 1.06 kg per week, and the control calves an average of 7.04 ± 1.52 kg per week. The test calves increased an average of 35% more in weight than the control calves did. When analyzed, statistically significant difference could be demonstrated between the groups regardless of farm. No statistically significant difference was seen between farms. The study population was relatively small, and the chest circumference gives only an approximate weight when calculated, making it difficult to draw conclusions about the entire population.
The test cows produced an average of 14.5 kg less milk per day than the control cows during lactation day 0-90, and on average 3.0 kg less milk after weaning, during lactation day 0-120. Statistically significant difference in milk yields could be demonstrated between the groups and between the farms. However, between the control and trial group after weaning, no statistically significant difference could be demonstrated on one of the farms.
When analyzing cell counts, a large variation was noted, the median value was 120,000 cells/ml for both test groups and 76,000 and 177,000 cells/ml, respectively, for the control groups. The cell counts were compared at farm level only. Statistically significant differences could be demonstrated between the groups and farms. On one farm, the test group had lower cell numbers than the control group while there were reverse conditions on the other farm, making it difficult to draw conclusions about the impact of suckling on cell count. Further studies with larger study populations and more farms would be needed to draw firm conclusions about how suckling affects milk production and udder health.