If you don’t serve the cow, you won’t get her in calf. The target six-week in-calf rate is 75%. This means that 75% of milking cows in the herd should be in-calf after six weeks of breeding.
When heifers are introduced at calving time, there should be 90% of the herd calved in six weeks.
To maximise submission rate, missed heats, silent heats and problem cows should be checked out early.
The best way to achieve this is to carry out pre-breeding heat detection or a pre-breeding scan. If doing heat detection, the easiest thing to do is to tail-paint all cows three weeks out from breeding and top up the paint once weekly. At mating start date, those still with paint on should be drafted out and seen by a vet.
In some cases, these cows will require more time and in other cases they will require hormone treatment. At least by identifying them early, action can be taken to get them back cycling.
The period at the start of the breeding season is often the busiest time of the year on dairy farms and can often be the most stressful. It’s important that farmers are mentally and physically prepared for the breeding season. In previous years, farmers and their partners could get away for a weekend break in April, but with COVID-19 restrictions that won’t be possible this year.
A cow-free weekend is probably the best that most farmers can hope for this year. It’s important farmers remember that while they may not be feeling tired or burned out now, they could be after three or four weeks of heat detection and AI.
Cows should be on a rising plane of nutrition in the runup to the breeding season. This means they should be consuming more calories today than they did yesterday and consuming more calories tomorrow than they did today.
In the livestock world, the focus is on UFL, or megajoules of energy, rather than calories, but the same principles apply.
The best way to get increasing amounts of energy into cows is to feed them high-quality grass. Firstly, high-quality grass is higher in energy than low-quality grass and, secondly, it is higher in digestibility, meaning cows will eat more of it – a double benefit. Focus on getting good residuals at every grazing but not pinching the cows too much.
Studies have shown that heifers who go from a low to a high plane of nutrition pre-breeding will have better fertility than heifers who have been on a high plane of nutrition pre-breeding. Almost like the principle of flushing ewes pre-breeding, putting cows on a rising plane of nutrition will help to ensure they are gaining body condition score prior to breeding.
The target body condition score (BCS) for breeding is between 2.9 and 3.25. Cows within this range have the best chance of going in calf early in the season. The best time to manage BCS for breeding was probably last autumn at drying off. What can be done to manage BCS now? The only real option is to put very thin cows (BCS of 2.5 or less) on once-a-day (OAD) milking. They should stay on OAD until three weeks after they are bred.
Feeding extra supplement to thin cows may improve their energy balance, but not if they produce extra milk from the extra meal. Reducing their energy offtake by going to OAD will be a more effective way of improving the energy balance.
There is no substitute to heat detection for a successful AI-based breeding season. Whether an automated system or simple tail paint or just observation is used, something or someone has to monitor the cows for signs of heat.
So what are the signs of heat? The first thing to say is that oestrus or heat is a spectrum and in any herd there will be cows coming into heat, on heat and coming off heat. The following are the signs associated with each period:
Cows coming into heat (duration of six to 10 hours):
Cows in heat (duration two to 30 hours: average 15 hours):
Cows after heat:
Farmers should monitor cows for signs of heat at least three times per day. This includes the two milking periods and one other time, ideally late in the evening. Farmers with the best breeding results will pay very close attention to heat detection and spend time monitoring cows.
Heat detection aids are an essential piece of technology. They can be as simple as tail paint, crayons, scratch cards, kamars or more elaborate such as automated devices and wearables. However, they are all only a guide.
From what I can see, no one device or method is going to be 100% accurate and some judgment by the herdsperson is required in the case of the “is she, isn’t she” cases when you are not sure if the cow is bulling or not.
Facilities Whether doing DIY AI or getting a technician, the person doing the AI has enough to be doing to do the job correctly than worry about the cow getting away or a gate falling. Safe, clean and efficient handling facilities are key to avoid stress on both the cow and man. Likewise, good drafting facilities make the job of picking out cows for AI far easier.
Before the start of the breeding season, everyone working on the farm doing AI should go on a refresher course.
Where farm staff are present, especially where new staff have been employed, the farm owner or manager should run through the signs of heat and discuss the protocol for the breeding season so everybody is mentally fresh and fully understands what is happening.
Don’t presume that just because someone has an agricultural qualification or has worked on a farm previously knows what the signs of heat are or the biology surrounding breeding.
Keeping good records is critical. This is especially useful when you are unsure as to whether a cow is bulling or not as you can check back to see when she was previously served. A breeding chart on a wall with the cows and their first- and second-choice AI bull is also useful.
Many farmers will carry around a small notebook or a diary with them and write in any cow bulling, as well as any cows hanging around with the bulling cows, and will keep a close eye on them over the coming days. Remember to periodically transfer the information to HerdPlus or farm software programme if doing DIY AI. Monitor progress weekly – for a 90% submission rate, 30% of the herd should be submitted each week for the first three weeks of breeding.