Scan cows to plan for 2011 calving
Published 07/09/2010 | 05:00
The breeding season should be finished now. However, stock bulls are still running on many farms. Cows bred now will calve next June, resulting in a short, non-profitable lactation in a grass-based system.
It is now time to find out how you got on with this year's breeding programme, to plan for next year's calving season and subsequent breeding seasons.
Scanning is an excellent tool to give you a picture of the reproductive status in the herd. However, the information from scanning is dependent on the operator using the equipment.
Aim to have your cows scanned no later than four months from the start of the breeding season. This will give you the most accurate information. Pregnancies can be identified from 21 days after breeding.
It is considered a safe pregnancy from 35 days of gestation. The ageing of pregnancies can be accurate to within five days of the true age of the foetus, up to 120 days of gestation.
Cows identified as non-pregnant should be assessed for suitability to go into an autumn-calving programme or for next spring's breeding programme. It is difficult to manage empty (dry) cows which are recycled to the following spring. Scanning will tell you if these empty cows are prospective candidates for subsequent breeding.
The sex of the pregnancy can be identified accurately between 51 and 120 days of pregnancy. Some farmers use this information to cull cows which are carrying Friesian or Jersey bull calves and are not suitable for breeding next year because of health problems. Many farmers get maiden heifers scanned to identify the sex of the calves. Subsequently, they plan the sale of in-calf heifers. Knowing the sex of the dairy cows now will enable you:
- To know if you have enough potential replacements in advance;
- To buy extra dairy calves if needed.
Scanning will identify cows carrying twins up to 120 days of pregnancy. However, many cows which start with twins will lose one or both pregnancies. The incidence of embryonic mortality is higher in cows carrying twins. This continues to occur at a higher frequency in the second and third month of pregnancy. Cows carrying twins need better management from the fourth month of pregnancy.