House Cow Basics: Pregnancy & Calving

Biscuit watching over her newborn calf

Guidance on getting a cow in calf, the oestrus cycle, and the calving process, as well as preparing for that all important first milking.

For most smallholders, using artificial insemination (AI) to impregnate your dairy cow is the only option. It might seem tempting to take her round to ‘visit’ a neighbour’s bull but the biosecurity risks will be high and he may well be an unsuitable breed to put on your cow. This is particularly important for small dairy breeds like the Jersey cow, as a commercial beef bull will likely result in a calf too large for her to calve unaided, and a stressed calving often has long-term health and reduced fertility consequences for the cow.

BASICS OF THE COW CYCLE

A cow’s regular cycle is around 21 days but can be anything from 19-24 days. As an egg follicle gets closer to being ready to ovulate it stimulates the release of oestrodiol which triggers the production of a thick vaginal mucus called a 'bulling string', relaxation of the cervix and increases blood supply to the uterus in preparation of receiving the egg.

Oestrodiol also triggers the release of luteinising hormone (LH), which is the hormone responsible for ovulation. Ovulation occurs approximately 32hrs after the LH release, however, it can be as long as 36hrs in some cows.

These hormonal changes are what trigger a cow to start to show oestrus or ‘bulling’ behaviours in the approximate order and timing shown in the attached diagram, culminating in ‘standing heat’: when she has a strong desire to stand to be mounted by other cows, or a bull.

BULL VS AI

A bull can detect those hormonal changes long before she is ready to be served. He will trail round after her, sniffing her vulva, resting his chin on her back and paying her considerable loving attention. He will make 'false jumps’ to test to see if she is receptive, but she will only stand to be served when in ‘standing heat’.

When it comes to AI, observation is key because her bulling behaviour is intended to work in harmony with the natural service of a bull. The fresh sperm of a bull will easily survive 24hrs inside the cow. Whereas the lifespan of sperm that have been stressed via the collection, sorting and freezing process when made up into AI straws is closer to 12hrs after insemination. Thus, getting the timing right is key to a successful AI service.

GETTING THE TIMING RIGHT

Months before planning to get your cow pregnant, get to know her cycle and start watching for oestrus behaviours as described in the attached diagram. Note down the dates and times you observe each behaviour in a ‘bulling diary’. Pay particular attention to identifying the time of the start of those behaviours to help you identify when she might come into ‘standing heat’, especially if you don’t have another cow to support behaviour expression.

When you know she is in standing heat in the morning, call the AI technician to come that afternoon. If she is in standing heat in the afternoon, have her served the following morning. And if in doubt, have her served a second time 8-12hrs later to be sure of catching her.

THE CALVING PROCESS

Dairy cows are more prone to metabolic illness than beef cattle due to their propensity to give significantly larger quantities of milk versus their body size. Milk production requires high volumes of minerals to be metabolised by the cow, and the Jersey cow in particular, with her small body size relative to her high production, can struggle to meet these demands in the first few days if not fed appropriately.

It is very important that in the final 2-3 weeks prior to calving dairy cows are fed a high fibre diet and not given any supplementary feed, particularly no mineral supplementation. The high fibre fills the rumen and helps the calf stay in the correct calving position. The low minerals trigger the cow to start metabolising minerals from her own body stores ready for the high demand at calving.

About to calve: uddered up, swollen vulva, pin bone ligaments loose, slab-sided

In the days leading up to calving a cow’s udder will fill and her vulva will become swollen and loose. Calving is imminent when her ‘pin bones’, which are the ligament on either side of her tail-head, relax, and she takes on a ‘slab sided’ look, which is when the roundness of her belly is flattened by preparatory contractions.

It will be very obvious when she goes into labour: she will lie on her side with legs stretched out and she will be pushing. She will often look back at her belly or extend her nose forward as if looking up to the sky.

At this point, if there is no calf yet showing, it’s a good idea to place a clean hand inside and check you can feel a nose and two toes in the correct ‘diving’ position. A healthy cow in calf to an appropriate bull, should calve herself in about 20 minutes, but can take up to 2 hours. If in any doubt, it’s best to call the vet.

As the calf comes out, make sure the bag is broken over its nose and mouth and they are clear of mucus. As soon as she’s calved, a cow will immediately get up and start to lick clean her calf, which is an extremely important part of the bonding process. Check the calf is breathing and loiter to watch and ensure the calf gets up and suckles. Some calves are quicker than others but usually they will all be up, teetering around, within 30 minutes. A calf needs a good 2 litres of colostrum within the first six hours, this is a minimum of 300 sucks: watch and count.

Calves will try to stand soon after birth and instinctively look to find the udder and suckle

A cow will cleanse (pass the afterbirth) soon after calving and will usually proceed to eat the placenta. This can be quite difficult to watch but it contains many nutrients so if you can stomach it, let her eat it but just watch so she doesn’t choke.

Once calved, a dairy cow should be given supplementary feed in the form of organic Lucerne pellets, the best quality hay from a diverse pasture and free-choice seaweed meal to ensure she gets all the nutrients she needs.

PREPARING FOR MILKING

A cow should be left to bond with her calf for the first 24hrs and to make sure it has had plenty of vital colostrum. On day two will be the first milking. In order to prepare for this moment it is imperative that time has been taking in the prior months to develop a close, trusting relationship with your cow.

This must include her becoming totally at ease with being in the area where she will be milked and with you being up close and personal with her. It must also include you being totally at ease with handling her and being around her back legs without fear of being kicked.

To reach this point, bring her into the milking area regularly, use food as a positive reinforcement, take your time and be very patient. Make sure every encounter is a good one, for you both.