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23rd February, 2019

Prospects of compact calving scuppered by heavy rainfall and lack of sunshine

Article written by Dr. Dan Ryan in the Farming Independent, July 17, 2012

The heavy rainfall in the month of June has surpassed all records since 1947. The implications for the dairy industry in the current year and 2013 will indeed be phenomenal.

Farmers have had to face housing of cows by night in June and July. Grazing conditions have become very difficult on heavy ground with grass quality and dry matter intakes severely curtailed.

Cows365 can now collect data pertaining to cows scanned and integrate same with existing farm records for calving data, AI and natural service. This enables us to analyse data for the client immediately after the farm visit.

Over the past month, we have generated data pertaining six week and eight week pregnancy rates. Unfortunately, the figures do not make good reading. Six week pregnancy rates range from 30 to a 73pc with an average of 47pc for over 6,000 cows scanned.  The eight week pregnancy rate was 66pc based on a population of over 3,700 cows.  This data was collected from spring calving dairy herds with a focus on grass-based milk production. This data supports my previous contention that reproductive performance in dairy cows is unacceptably low to achieve the desired target of 85pc calving rate in a six week period. Replacement rates of 30pc will be needed on many farms to achieve the targets centred upon cost-efficient grass-based milk production.

The reduction in grass dry matter intakes associated with poor DMD and high moisture content has resulted in a significant loss of body condition score. Cows should now be gaining body condition. Our scanning records reveal an average of 17pc not pregnant for cows presumed pregnant greater than 30 days.

This is associated by either embryonic death or undetected heats or cows which have abnormal heat cycles.  This scan data will have a negative impact on calving spread in the spring of 2013. The stress associated with the weather has had a major impact on the figures presented above.

Unfortunately, cows with embryonic mortality or not cycling will not resume normal heat cycles unless the problem is identified and rectified. Scanning now will still enable you to get cows calving in late April or early May next year. Research data has shown that embryonic mortality in a cow at 30 to 40 days of pregnancy can result in a six week interval to resumption of heat cycles. This will result in these cows being culled if not identified by scanning.

The weather has also played havoc on the harvesting of silage. Many farmers have still failed to make silage. Silage quality and quantity will be restricted on many farms for the forthcoming winter. Stocking rates have increased on many farms in preparation for post 2015 removal of milk quota restrictions. Over stocking of cows is creating many of the reproductive problems encountered today. Many farmers would be better off to sell excess dairy stock above resources available to manage them on the farm.

Stock bulls are now in use on most dairy farms to mop up empty cows. A stock bull will not put cows in calf which are not cycling or have embryonic mortality. We have encountered many large dairy farms, which do not have sufficient bull power for the number of cows remaining not confirmed pregnant.

Many bulls suffer with feet and leg injuries or are infertile. After scanning your cows, identify the cows not confirmed pregnant by applying tail-paint to the tail head. It may be a good insurance policy to AI those cows seen in heat while running with the stock bull. Some bulls are selective in the cows mated, where several cows are in heat simultaneously with one stock bull, some may be left unmated.

Dr. Dan Ryan is a  Bovine Reproductive Physiologist and can be contacted at