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13th June, 2021

Options for Breeding your Maiden Heifers

Spring breeding programmes will begin on dairy farms over the next four weeks. With milk price under pressure, many farmers are considering either reducing the use of Friesian AI, greater use of beef AI, use of stock bulls or no AI this year.
Dairy markets will recover. This is the breeding season to use Friesian AI to have replacement stock in your herd. When profits return to milk production I cannot emphasise sufficiently, the importance of biosecurity from a disease perspective. The use of AI gives you the opportunity to optimise your herd health status. This also affords you a greater opportunity to sell stock with a “known” health status.
Your breeding programme has to focus on two distinct groups of cattle, maiden heifers and dairy cows. In this article we will focus on the maiden heifers. You need to get them bred early in the breeding season to enhance their future survival in the herd. The majority of farmers considering the use of AI in maiden heifers want to get them bred quickly and use a stock bull to mop up the repeats. The progeny from your maiden heifers should be the best future genetics on your farm. Synchronisation programmes work well if your heifers are fit for breeding. This entails not alone size and body condition score, but also housing environment over the winter months. We encounter a significant percentage of maiden heifers in a prepubertal state when presented for a prebreed scan. These heifers are not fit for breeding. We currently recommend identifying this group of animals with a focus of getting them out to grass with supplementation of 3 Kg of heifer growing ration. This approach results in normal fertile heat cycles within three weeks. Some farmers use the prebreed scan to group heifers which can be synchronised with a prostaglandin injection either immediately or 6 days later. The prebreed scan will also identify those heifers for breeding over the following three days without the need for injection.
Alternative synchronisation approaches include “watch and inject,” “double inject” and “Rolls Royce”. The cost of these programmes increase with the order described. However, the time required for heat detection decreases, there is less risk of missed heats and some of the prepubertal animals will establish pregnancy with the “Rolls Royce” treatment.
In the “watch and inject” regimen, heat detection and AI continue for 6 days from the onset of the breeding programme. On the sixth day, heifers not bred are injected with prostaglandin. All heifers should be bred by the tenth day of your breeding programme. This approach works well when heifers are managed close to home. Remember that prepubital heifers will not respond to this treatment.
The “double inject” approach entails injecting all heifers on both day minus 14 and 2 prior to the start of the breeding season. All cycling heifers should be detected in heat over a three day period. Note that prepubertal heifers will not respond to treatment. The cost of this approach will range from 10 to 15 euro per animal excluding vetinernary fees.
The “Rolls Royce” entails the injection of a PRID or CIDR device pervaginum for 8 days with a prostaglandin injection on the day prior to removing the PRID or CIDR. Please note that the new PRID devices are easier to insert in maiden heifers and do not have the high device loss rates experienced with the old PRID device. All heifers should present in heat over a 1 day period. This facilitates AI and indeed fixed time AI on outside farms.
Some farmers might also consider inserting the PRID or CIDR devices 15 days after breeding for a 5 day period. This results in tight synchrony of repeats and reduces the risk of missing heats. This should be given consideration if heifers are managed on outside farms where you want to use AI to breed future replacements and reduce the risks of using stock bulls.
Stock bulls are an option for breeding maiden heifers. Genomic testing has enabled greater probability of replacements with desired production potential traits. Please ensure that your stock bull is fertility tested as in excess of 10 pc of stock bulls are either infertile or sub fertile. Any injury to a bull will impair spermatogenesis which will reduce his fertility 6 weeks later, while physically he might appear fit for purpose.
In summary, use AI in maiden heifers this year to breed future replacements when a recovery in dairy markets will pertain. Stock bulls are a necessity but do not put “all your eggs in one basket.” Beware of bull fertility.
Dr. Dan Ryan is a bovine reproductive physiologist and can be contacted at

Article written by Dr. Dan Ryan for the Farming Independent 5th April 2016.