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Keep on top of your cows' heat cycling

This is the first year that many dairy farmers have stopped milk production over the Christmas period. Normally, these farmers will milk late calvers and empty cows from the spring breeding programme during the winter period. Some of these cows would normally be bred to calve down next autumn, while others would be bred next spring.

Once again the risk of superlevy penalties has meant that these cows have been sold for fattening. Cull cow prices have been exceptional this year, which has encouraged many to dispose of empty cows.

Liquid milk producers and a hard core in manufacturing milk have begun their breeding programmes for calving from September. There is a radical difference in the genetic potential for milk production between autumn and spring calving cows. Many farmers in liquid milk production have pedigree Holstein herds with a genetic potential for more than 8,000 litres in 305 day yields.

The breeding management of the autumn cow is made more difficult by the requirement to house cows. The nutritional and housing needs dictate that they are optimised to achieve the desired reproductive management targets.


Heat detection is more difficult indoors. The signs of heat and duration of it are the primary concerns. The target of a 90pc heat detection rate among cows eligible for breeding is the exception rather than the norm. Genetics, housing environment and nutritional requirements have to be in sync to optimise heat detection rates.

Visual heat detection without any aids is generally used with dairy cows indoors. Based on a survey of dairy herds housed indoors for the winter, we have recorded heat detection rates using visual observations of 25-80pc. This was based on cows scanned and identified as cycling normally.

Research data show that missed heats cost around €200. There is a need for greater uptake of technology for heat detection. Tail paint is not used successfully by farmers indoors. Tail chalk is used to achieve heat detection rates in excess of 70pc on farms in the north of Ireland. This system is used by Genus, where they provide a heat detection and AI service for farmers.

The monitoring of cow movement is another approach to heat detection. The Moo-Monitor developed by Dairymaster has achieved heat detection rates close to 85pc in independent trials. This was again based on comparison with monitoring of heat activity using scanning. However, the ability of heat detection using this approach is dependent on the health of the cow. Lameness, poor body condition score, overcrowding and mycotoxins are all examples which will impact negatively on heat detection rates.

Teaser bulls with chin ball markers are a very effective approach to heat detection. However, injuries to the bull and false positives are issues preventing their widespread use indoors.

Scanning is an accurate approach to determine which cows are cycling and, more importantly, the stage of the cycle. Farmers use this approach to either induce cows to come into heat or set targets for cows to be detected in heat. Failing to meet these targets results in an action plan to induce cows to come into heat.

Pre-breed scanning of cows will identify problem breeders and those cows fit for breeding.

We are currently building a system whereby scanning will determine the health of your herd. This information can be used to specifically address the cause of problems and thereby preventative health management in the future.

Pregnancy rates in a survey of autumn-calving herds scanned by were 20-62pc. The average pregnancy rate was 37pc. Compact calving is not feasible with pregnancy rates at this level. One might blame the Holstein cow for poor reproductive performance. Genetics, inbreeding, health, nutrition and housing environment all interact to determine the pregnancy rate to a given service.

A major review of genetic and management practices are required to improve reproductive performance of dairy herds in Ireland. Cost-efficient milk production should not mean removing the genetic potential for milk production, thereby improving reproductive performance. Winter milk production systems favour a high genetic potential for milk production. Improving the systems of management will result in heat detection rates close to 90pc and pregnancy rates of 55pc. Ultrasonography is an essential tool in the drive for targeted reproductive performance in your dairy herd.

Dr Dan Ryan is a breeding management consultant and can be contacted at

Indo Farming