Farm Ireland

Friday 24 November 2017

Managing pregnancies can be crucial when superlevy looms


Dr Dan Ryan

The spring breeding programme for the dairy herd this year has been mixed so far. April was excellent for heat detection and pregnancy rate to AI, while May's low night-time temperatures resulted in a high incidence of grass tetany where farmers discontinued concentrate supplementation with inclusion of Cal Mag.

As this month nears an end, the primary concern on the mind of most dairy farmers is the cost of exceeding quota in the event of a superlevy. The actions being suggested are in many cases ludicrous. We are still in a breeding programme for spring calving in 2012. Stress of any form has to be avoided. More than 90pc of cows bred will start out in-calf. Early embryonic death will result in cows coming back into heat between 10 and 24 days. Embryonic death beyond day 14 after breeding will result in cows coming back to heat at various intervals up to nine weeks after breeding.

Farmers become very frustrated when they see cows repeating, especially two months after service. Various environmental stressors cause embryonic death. However, death of an embryo will not result in an immediate return to heat. The early stage pregnancy in the cow can be compared to a "baby in a blanket". The blanket maintains the signal for pregnancy for a long period after the embryo dies. Therefore, the cow cannot come back into heat on her normal three-week cycle.

Many dairy farmers now use scanning to identify if cows are pregnant. This gives peace of mind in addition to the return on investment by reducing days open in non pregnant cows. This is where expertise is required to identify why the cows are not pregnant.

Low pregnancy rates may be associated with either high embryo mortality, poor heat detection rates, infertile or sub-fertile stock bulls. Investigation of causes reveals a combination of the above in many cases.

Preventative health management is the key to reproductive success in your herd. Scanning, used in combination with milk analysis for various minerals, bacteria, parasites and viruses, will help identify underlying stressors. Dr Tom Butler, FBA, Cappoquin, Co Waterford, has pioneered the development of a combined assay for a variety of immunosuppressants.

Farm visits over the past month have always entailed some discussion on how farmers are managing their herd when facing a superlevy.

Advice has ranged from selling cows to removing concentrate supplementation and once-a-day milking. Some farmers plan to shorten their breeding season in the hope of culling more of the late calvers next year.

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In my opinion, one should not induce any form of stress on the dairy herd while the breeding season is still in place. For most farmers, bulls will not be removed until the end of July. Take decisive action to manage your quota allocation when the breeding season is over.

Focus now on identifying empty cows that are presumed pregnant. This will give you the opportunity to get these cows back in calf. Also, early pregnancies (day 25-90) and twins can be accurately identified and aged at this stage of the season. Remember pregnancies can only be accurately aged up to 110 days of gestation.

Therefore, scan your herd now and one month after the end of the breeding season. You will only need to scan cows not previously scanned pregnant on this second scan. This information will enable you to accurately plan milk supplies in January through March 2012.

Many farmers will not have the option of milking cows through the winter this year.

Take the option of culling cows earlier this autumn. Plan your milk supplies based on an earlier dry-off date or once-a-day milking from September onwards.

Dr Dan Ryan is a breeding management consultant . Contact him on

Indo Farming