Dairy cows are more motivated to reunite with their calves if their calves have been suckled, meaning that their young have nursed from the mother cow’s udders. This is most likely due to the fact that oxytocin, a hormone that is involved in the bond between the mother and calf, is released when the calf nurses.
Margret L. Wenker and her colleagues studied holstein cows that had just given birth. They wanted to see how different interactions allowed between the mother and young lead to different levels of motivation to reunite with the calf. They also wanted to see if there was a difference in the time it took a cow to make nose contact with her offspring once reuniting with her young, this period between sight and contact is known as latency. Finally, they also wanted to know if the amount of maternal care (measured by time spent licking) given to the calves varied based on previously allowed interactions.
There were three different levels of interactions that made up the treatment groups. One group consisted of cows and calves that were separated soon after birth, and they were only allowed contact when measuring the motivation of the mother to reunite with her calf. A second group of calves were allowed to spend the night with their mother, but they were prevented from suckling. And the third group of calves were also allowed to spend the night with their mother, but these young were allowed to nurse.
To measure the motivation of the cows to reunite with their calves, a one-way push gate was installed inside the barn that these cows lived in. This gate was attached to a pulley system that could be loaded with different weights. The cow would have to push through this gate in order to come in contact with their young who was on the other side. The more weight that the cow would push, the more motivated she was to reunite with her calf.
This study found that suckled cows were more motivated to reunite with their calves. There was no difference in the motivation between cows that had been separated from their calves, and calves that were allowed contact with calves but didn’t suckle. Suckling has been known to be one of the most pleasurable activities between a mother and her young because oxytocin is released, which has rewarding effects on both the cow and calf. In humans, oxytocin is known as the “love hormone,” and promotes a feeling of love and well-being. Similar feelings are felt in cows, and this hormone strengthens the bond between the mother and her calf, which could explain the greater motivation for suckled cows to reunite with their calves.
Maternal care in cows generally consists of licking, nursing, being close to, and protecting their calves. This study found no relationship between the interactions allowed during the treatment period, and the time that cows spent licking their young. They also found no relationship between the latency for the mother to make nose contact with their young once reunited.
On most dairy farms, calves are separated from their mothers soon after birth, and the calves are normally bottle fed. In these cases, the mothers don’t usually nurse (or really show any maternal care towards) their calves. Previous studies have shown that cow-calf bonds can be formed from just being around each other without nursing; however, we can see here that suckling is a very powerful behavior in these dairy cows that forms an even stronger bond beyond the one formed from regular contact.
Wenker ML, Bokkers EAM, Lecorps B, von Keyserlingk MAG, van Reene CG, Verwer CM, Weary DM. 2020 Effect of cow-calf contact on cow motivation to reunite with their calf. Nature Scientific Reports 10:14233. https://doi.org/10.1038/s41598-020-70927-w
