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15th December, 2017

ACT NOW TO MAXIMISE PREGNANCY RATES IN YOUR DAIRY HERD

cutting silage in bad weather

Cutting silage which was used to feed cattle that were still indoors in May

Breeding programmes for grass-based spring calving systems are now nearing mid-way. Fodder shortages, poor grass growth rates, increased stock numbers and limited housing space have resulted in poor reproductive performance to date where cows have been compromised.

It is essential that you have fit cows and heifers for your breeding programme.  It will pay to feed concentrates to cows at grass while a breeding programme is in place. This may be an extraordinary year in terms of grass growth, but we need to reflect on the need for insurance in the business which will see a return to increased stocks of silage to facilitate risk periods associated with poor grass growth and ground conditions.

How do we address the current status of the breeding programme?

It is essential to get a full picture of herd health status. This can be achieved by scanning the reproductive tract of each cow in the herd. Reprodoc have developed USART technology which provides you with a report detailing the fitness of your cows for breeding*.

This unique scanning technology can be used by you to make better informed decisions about the management of your herd. At this stage of the breeding programme, you have cows not detected in heat for AI. These will consist of late calvers less than forty five days calved and cows which are eligible for service but not detected in heat. The USART technology will identify if those cows are cycling and at what stage of the heat cycle the cows are in. This information will allow you to plan the breeding of cows not AI’d to date.

Scan cows that are served over 20 days.

This will enable the identification of cows which have had embryonic mortality. Embryonic death will prevent cows from returning to heat. The pregnancy consists of the embryo proper and trophoblast that will ultimately form the afterbirth. The trophoblast provides the signal for pregnancy. Even though the embryo dies, the pregnancy state will be maintained by the pregnancy signal produced from the trophoblast. This ultimately results in cows not returning to heat for up to nine weeks after embryonic mortality. Up to 10% of cows will have embryonic mortality beyond 20 days after breeding, which can cost an average of €250 per case. The USART technology can accurately identify embryonic mortality enabling corrective action for cows to return to heat for breeding and reduced days open.

Non return rates may suggest pregnancy rates close to 70%. Late embryonic mortality, missed repeats and reproductive abnormalities will result in a true pregnancy rate close to 50% in cows. The hidden cost of just one missed opportunity for breeding at this stage of the breeding season is €250 per missed heat**. USART Technology will cost the farmer €550 for a 100 cow herd giving a potential nine-fold return on investment.

Twin calves

The incidence of twins is greater in high production type cows

Reprodoc consider the scanning of cows prior to 35 days of pregnancy as non-pregnancy diagnosis. Implantation of the embryo is only complete at day 35 of gestation and subsequent loss of pregnancies is less than 5% except in the case of multiple pregnancies. The incidence of twins is greater in high production type cows. However, the risk of embryonic/foetal mortality can be as high as 50% where twins are in the one horn. USART technology can accurately identify the type of twin pregnancy and the associated risk of pregnancy loss. Reprodoc always recommend a second scan four weeks later for those cows carrying twins.

Lush grass regrowths with rapid uptake of nitrogen can compromise fertility. Keep a vigilant eye on butterfat to protein ratios. The risk of acidosis is high when fibre is minimal in fresh grass regrowths. A drop in the butterfat to protein ratio indicating acidosis needs to be addressed by inclusion of a fibre source in the diet.

In conclusion, corrective action can be taken now to maximize pregnancy rates in your dairy herd. The innovative USART technology offers you the opportunity to take control of your breeding programme.

* USART (Ultragraphic Assessment of the Reproductive Tract)
** Teagasc Advisory Newsletter June 2010
reprodoc.ie
Dr. Dan Ryan is a breeding management consultant and can be contacted at reprodoc.ie