Effect of calf suckling on dairy cows’ milk yield, milk fat and protein and somatic cell counts, and daily weight gain in calves.
University of Edinburgh and SRUC, MSc project
(Associated with University of Makarere, Thűnen Institute for Organic Farming, Tanzania Livestock Research Institute)
This study used data from the Thűnen Institute of Organic Farming, Germany, where an experimental cow-with calf system has been run for over 10 years. The study aimed to compare milk yield, milk composition and calf growth between a group of cows in a standard early calf-separation system and a group of cows in a cow-with-calf system. Growth of the calves and aspects of udder health were also assessed.
In modern UK dairy farms, cow and calf are typically separated within the first 24h after birth; primarily to allow cows to enter the milking herd and maximise milk available for sale. It is thought early cow-calf separation reduces exposure of young calves to disease carried by adult cows and makes handling the two groups of animals easier. However, there is growing public concern about early separation of cow and calf globally, and some farmers are seeking alternatives.
Though most farms running a cow-with-calf system allow the calf near-continuous access to the cow, cows are typically milked through the parlour once or twice daily to maintain the farm’s saleable milk output. As dairy farmers’ primary earnings are from the sale of milk, a key question about the cow-with-system is centered on what level of saleable milk yield can be expected from cows when they have a suckling calf. However, milk taken by the calf should not be thought of as being ‘lost’. Continuous access to the dam can promote good growth rates in calves, and sale of calves can be a source of farm income. Additionally, udder health in the cow may be positively affected by calf suckling.
Treatment groups and housing
108 primiparous dairy cows of two breeds (German Holstein and German Red Pied) were allocated to two study groups: calf-suckling and conventionally managed. Groups were housed in cubicle sheds during winter and allowed outdoors in spring and summer, from April or May.
41 cows in the calf-suckling group with 40 calves
67 cows in the conventionally managed group with 15 calves
Cows and calves in the calf-suckling group were housed together continuously in a cubicle shed and all cows were milked twice per day in a tandem milking parlour
Calves in the calf-suckling group had continuous access to their dams outside milking periods and had a designated ‘creep’ area with an automatic selection gate to exclude cows
Conventionally managed calves were removed from their dams at 24h of age and housed in single hutches for one week and then moved into group pens, unless sold or euthanased
Conventionally managed cows were milked twice per day and housed in a similar cubicle shed
Data was collected on cow milk yield, % fat, % protein and somatic cell scores monthly across the lactation period (305 days). Calf body weight was measured immediately after birth and then twice per week until weaning (90 days). Growth rates from a total of 55 calves were recorded, with 40 from the cow-with-calf group and 15 from the conventional group.
Results
Cows in the conventionally managed group produced more milk than those in the calf-suckling group
Milk of the conventionally managed cows had a higher fat content, but there was no difference between the two groups in the protein content
Somatic cell scores were lower in the calf-suckled group than in the conventionally managed group
Calves in the calf-suckling group had higher daily weight gains than the calves on the conventionally managed system
Discussion
Cows in conventional systems give greater milk yields in the parlour than cows with calves. The fat content of the milk is also lower in the cow-with-calf system. This has also been reported in other studies and may be due to the removal of the residual milk by the calves, as this portion of the milk that has the highest concentration of fat. There was no effect on the protein content.
The better somatic cell score indicates that calf-suckling systems are beneficial for udder health. This has also been shown by a number of other studies and may be due to the better udder emptying and reduction in residual milk achieved by sucking. Calves in the suckling system show higher growth rates. This may be due to the ad libitum access to milk, but also to the care provided by their dams.
Overall, the study showed that the volume of milk collected in the parlour in this study from cows in a cow-with-calf system was approximately 25% less than in a corresponding group on a conventional system. However, there were health benefits for the cows and better growth rates in the calves.