The bonding process, as the cow learns to recognize her new calf, and commits to caring for that calf, is a complex blend of hormonal- induced and learned behaviour. Mature cows that have had calves before are more apt to quickly mother their offspring than first-time heifers. Understanding maternal behaviour in cattle and how to help prevent confusion or stress at calving (and what to do that might help the bonding process in heifers or cows that reject their calves) can be beneficial to stockmen.
HORMONES ARE THE DRIVING FORCE
Experience is part of the equation, since older cows tend to be more consistent mothers, with more maternal drive, than heifers, but we tend to give experience more credit than it is due. “The cow is most receptive to wanting a newborn calf when she gives birth,” says Dr. Joseph Stookey, a professor of large animal clinical science at the Western College of Veterinary Medicine in Saskatoon.
Hormones initiate and drive most of what we perceive as maternal behaviour. “Some cows become interested in any newborn calf, up to a week before they actually calve. Their hormone pump is already primed and those hormones are already reaching a level that makes them receptive to any new calf, even if it’s not theirs,” he says. An older cow already has the system primed, and when she starts showing interest in other cows’ calves, you know she’ll be calving soon.
“At the other end of the spectrum are the cows that calve and don’t have proper hormone profile or levels, and don’t want their calf. We see this most often in first-calf heifers, or in some of the females we assist, or those that must be delivered by C-section. If it’s too much of a rodeo getting that cow in for assistance, or she undergoes too much trauma, you can expect her to be a little less interested in the newborn calf. There may be other hormones overriding the whole system, due to stress, pain, and some of the drugs that were used during a C-section,” says Stookey.
Changes in progesterone and estrogen levels initiate the birth process, but rising oxytocin levels trigger maternal behaviour. Oxytocin is released in the brain during birth. “Its presence in the olfactory bulb of the brain helps explain the role of smell and importance of odour in the bonding process, with the cow recognizing her own calf by smell and always able to pick her calf out of a group of calves,” he says.
“Cervical stimulation is crucial for proper hormonal triggers,” explains Stookey. Release of oxytocin is caused by stretching/stimulation of the cervix and birth canal. Studies with sheep showed that cervical stimulation (gradual dilation of the cervix as the feet of the fetus push against it with each uterine contraction, and then passage of the fetus through cervix) is one of the main triggers for oxytocin release.
“If you do a C-section there isn’t much cervical stimulation, since the fetus doesn’t come through it. This could be another factor that plays a role when a cow is slow to mother her calf. Analgesic drugs used during a C-section to block pain can also interfere with oxytocin release,” says Stookey.
First-calf heifers produce less oxytocin than cows who’ve had previous calves — and this may explain why heifers may be less motherly and more apt to reject or abandon their calves. “Giving birth seems to prime the system and allows for release of larger quantities of oxytocin with subsequent births. Heifers therefore have a disadvantage on two counts. They are less experienced than cows, and also have lower levels of oxytocin release in the brain during calving,” he says.
A few heifers are indifferent to their calves at first, and within 12 to 24 hours become more motherly. In some instances, a heifer may not have much milk at first, and then as her milk starts to come in, she becomes more interested in her calf. Oxytocin is the hormone associated with milk letdown, and is also closely tied to maternal behaviour. If a heifer is indifferent, or actively rejects her calf, if you can assist the calf in nursing, she generally becomes more receptive to motherhood. The act of suckling stimulates release of oxytocin.
“If you can stimulate milk letdown a few times by assisting the calf in nursing, the hormone comes on board and improves maternal behaviour. Oxytocin can switch off the heifer’s aggression, reluctance or fear, and turn it into interest and mothering,” says Stookey. These hormones of motherhood can completely change a heifer’s attitude.
The cow or heifer goes through a series of behaviours as she reacts to various sensory clues provided by the calf and the birth fluids. If she’s lying down as the calf slides out of the birth canal, she will generally raise her head and look over her shoulder to get a glimpse of the calf.
“Any movement of the calf at this stage (raising its head or shaking its head) is a strong stimulus to the cow to get up and turn around to smell the calf and start licking it. Calves that shake their heads and are vigorous elicit a stronger response in the cow; they are more attractive to the cow than weak or dead calves. In one study, we tracked more than 200 cows and heifers that required veterinary assistance (either a C-section or a pull) and found that a significantly higher percentage of calves which were judged weak at birth were rejected, compared to calves judged as average or strong,” says Stookey.
“The smell and taste of birth fluids is another strong attractant that further drives the maternal behaviour and stimulates the cow to lick the calf. If the mothering process is interrupted before the cow licks the calf, then the likelihood for rejection of the newborn increases. It’s not uncommon to find that females which have had diffi cult deliveries and required human assistance show signs of rejecting their calves,” he says.
“One technique that has been successful in facilitating proper maternal response has been to smear birth fluids across the muzzle and tongue of the dam following delivery. This seems to jump-start the maternal response. Simply pulling the newborn to the front of the mother may not be sufficient stimulus to start the maternal behaviour, especially for some first-calf heifers. Pouring feed onto a newborn calf may entice some reluctant mothers to approach the calf and eventually come in contact with the birth fluids as they eat the feed. I suspect that any attractant that can stimulate the cow to lick the calf would be useful,” says Stookey.
As the cow licks the calf she begins the bonding process and learns her own calf’s smell, to enable her to identify it. She generally won’t let any other calf nurse her; she first has to smell it and make sure it’s hers. This is an important part of bonding, and probably the reason that cattle instinctively seek a place to calve where bonding won’t be interrupted. Because newborn calves are soon up and walking, and can mix with other calves early in life, the cow must be able to recognize and discriminate between calves soon after birth.
If cows are too closely confined, with many calving cows or heifers in a small area, they don’t get a chance to leave the herd and find a private place to calve. It’s their natural tendency to seek a place where they can give birth and bond with the new calf without interference from other herd members. When a lot of females are calving in the same small area, some may try to claim another’s newborn calf. If a heifer is intimidated by older cows she may not be able to mother her calf, and “mix-ups” may occur. If a calf wanders around and tries to nurse other cows, he may be kicked and bunted and become discouraged and give up.
“First-calf heifers are more likely to isolate themselves from the herd than mature cows. Researchers who have studied this behaviour suspect heifers leave the herd to move away from more dominant individuals that might disrupt bonding,” says Stookey.
“In the 1980s our college sent vet- erinary students to a large commercial ranch to assist in calving 1,000 heifers. They observed about 10 per cent of heifers mis-mothering calves. There were instances of two or more heifers trying to claim the same calf, heifers abandoning their calves, and heifers stealing calves from other heifers,” says Stookey.
Much of this mis-mothering can be avoided by providing adequate pasture space so heifers can leave the herd and isolate themselves at calving. If weather conditions necessitate closer confinement for shelter, close monitoring — and quietly moving each calving female to a private place to calve, such as her own barn stall — will prevent those mothering problems.
It’s best if you can move the female before she calves. If you try to move her and the calf afterward it can be disruptive to the bonding process, especially for a heifer. Older cows are more likely to follow you and the calf (especially if you put the calf in a sled or some other conveyance low to the ground so the cow can follow along and keep sniffing her calf). Heifers are more apt to become confused, especially if they haven’t had much time to lick and bond with the calf. Often the heifer or cow will run back to the birth site, looking for the calf, rather than following you or allowing herself to be herded to the barn.
“You can’t just take the calf in the house to warm it up, then put the calf in the barn and move the heifer to the barn and expect her to mother it. She’s more apt to accept the calf as her own if you take it back to the birth site. This makes sense according to everything we know about the recognition process. If you grabbed the calf before she filled in that template of recognition/bonding, she may not recognize the calf in the barn as hers. She’ll try to get back to the spot where she gave birth, to find her calf,” says Stookey.
“We saw this several times when we took students, who were enrolled in a calving rotation, out to a ranch in Alberta. If we had to pull the calf (out in the field) and the cow jumped up and ran off, we sometimes told the students to take the calf to the barn and that we’d get the cow in. That doesn’t work,” he says. You have to make sure the cow has a chance to smell that calf, or she won’t recognize it as hers after you get her to the barn. “If you need to move a calf from the birth site, make certain the cow follows the calf. Also do not totally dry a newborn because the birth fluids are a strong stimulus in eliciting maternal behaviour,” he says.