Mating’s trifecta: bulls, heat and AI

Heat detection, artificial insemination practices and bull management are three pieces of the framework for good reproductive performance in dairy cows.

Tail paint is a good tool in the heat detection kit but only if used properly. Some farmers do it well but some are a bit haphazard. Correct placement is a strip of tail paint applied to the rear portion of the backbone of each cow, not too far up and not too far down the tail and not too wide. Deviation from this may lead to confusion and misinterpretation of a cow being on heat. A cow is on heat and ready to be mated when she stands to be mounted by a herd mate or a bull; the tail paint will be rubbed off as the animal dismounts. If a cow walks away while being mounted, she may not be fully on heat even if some of the paint has been rubbed. Other sources of confusion could be during wet weather when cows prefer to stand with their backs to the rain rather than being mounted by a herd mate, or if a cow is on heat for a particularly short period and only some paint is removed. Therefore it is critical to look for other signs of heat to confirm the optimal timing of artificial insemination. Using tail paint with another heat mount detector along with paddock observations will help achieve this. In addition, there are several secondary signs such as delayed milk let-down, being restless or mucus around the vulva that can help with decision-making. Managing cows that have been drafted out for insemination should be stressfree. Provide access to quality food and water and do not leave them standing on the yard for extended periods. Move the cows into the yard for insemination quietly and without rushing. Once inseminated, return the cows to the herd as soon as possible and avoid them standing at a back fence waiting to get to the break. Carefully consider how many bulls you require for the natural mating period. Just because you had eight bulls last year does not mean eight bulls will be enough this year. Consider your submission rate and non-return rate to determine an estimate of non-pregnant cows at the end of AI. Determine the number of bulls required by using a ratio of one bull to 30 non-pregnant cows with the same number of bulls resting. Always round up numbers to the nearest bull and never run fewer than two bulls per herd. Bulls should be in teams and rotated regularly between resting and working. Reviewing your heat detection processes, AI systems and bull numbers

| Move the cows into the yard for insemination quietly and without rushing.

HEAT DETECTION

Tail paint should be applied: • No more than 20cm long. • No more than 5cm wide over the rear segment of the backbone. • No further back than the start of the tail. • Sufficiently thick to cover the skin with some hair fibres still visible.

will contribute to optimal conception rates and in-calf rates, leading to a good mating outcome. Speak to your local Farmlands or Donaghys TFO about Donaghys tail paint and how this can benefit your herd.

For further information, contact your Farmlands Technical Field Officer or the friendly team at your local Farmlands store.

Article supplied by Donaghys