Enrollment of animals for the most recent batch began February 2, 2022 and continued for 6 weeks. A total of 25 cows and 26 heifer calves are included (1 set of twins). There are multiple large differences between this batch and previous batches. Firstly, this batch is utilizing a different indoor pen than that previously used. This new pen is smaller, and has been organized to operate with a free traffic system, as opposed to the Feed First system (DeLaval) that was previously in place for batches 1–4. The cows can now move freely between the different resources in the pen, including the feed alley, stalls and automatic milking robot. In order to encourage cows to enter the milking robot at least twice per day, the 2 concentrate feeding stations have been turned off and instead, the cows receive higher rations of concentrate in the robot and mixed into their silage. So far, this system of free cow traffic is successful; many cows are entering the robot of their own free will more than twice per day, either for additional milkings or simply for a portion of concentrate.
A second large change in this new batch is the elimination of a cow-calf contact area. Instead, the entire pen is occupied only by the cow-calf pairs and triad, and – with the exception of the milking robot and waiting area – the calves have access to the entire unit and its resources. As before, a calf creep is still located along one side of the pen, providing calves with a separate lying area. Water, roughage and concentrate are also available to the calves within the creep.
In May, the cows and calves will be turned out to pasture, where we can note a third difference from previous batches. Much like their dams, the calves will be able to move freely between the indoor pen and outdoor pasture. This will remain the case until the first calves are weaned.
Four and six month treatment groups
As in batch 4, this batch will once again randomly allocate each of the calves to 1 of 2 different treatments: weaning and separation at either 4 or 6 months of age. When the first group of calves are weaned, it will be done so abruptly, and the calves will be moved directly into a separate pasture where they will have access to shelter, food and water. The pasture is located close to the barn, so that the cows are forced to walk past it (and the calves) on their own way out to pasture. A section of the fence between this walkway and calf pasture will be modified to allow for restricted cow-calf contact. Live observations will be conducted to record fenceline interactions that may occur between cows and calves in the weeks following separation.
Cows with and without experience of these systems
Another unique aspect of this particular batch is the fact that some of the cows were previously raised as calves in earlier batches of the Cow and Calf Together project. These cows – all primiparous – make up 1 of 4 unique categories of dams found in this batch, the others being:
· Primiparous cows that were conventionally raised
· Multiparous cows who have experience raising calves in a cow-calf contact system
· Multiparous cows with no previous experience
Video cameras were installed over each of individual calving boxes to facilitate observations of maternal behaviour at a later point. Furthermore, all of the cows are equipped with various sensor equipment that can detect activity patterns and estrus behaviour. This behavioural data will be combined with other automatically-collected data (i.e. milk yield) to observe how cows that were previously raised in a cow-calf contact system perform during their first lactation. Milking, feed intake and fertility data are also available for such cows not currently housed in a cow-calf contact system, and will be analyzed as well.