For a lot of dairy farmers, first-cut silage is wrapped up and for the spring-calving herds, the fifth week of the breeding season is now coming to an end.
On a lot of farms, where they are breeding their own replacements, the cows should be served at this stage.
Calving down heifers late will mean the heifer will always be on the back foot and require a lot of time and cost to catch up with early calving heifers.
Where there is signs of heifers not coming into heat or any problem cows on the farm, scanning needs to take place to rectify what the issue is, so a decision can be made.
It is important to remember, when you are selecting beef AI or stock bulls, to use only easy calving and high dairy beef index (DBI) to see out your breeding season.
Cut-off point to the breeding season
Fertility performance in dairy herds over the last number of years has improved dramatically, thanks to the emphasis on EBI, improving dairy breeding as a whole.
Thanks to this, a compact calving at the start of the grass growing season is a frequent occurrence around the country.
In order to maintain this compact calving, and take full advantage of this improved breeding, a farmer needs to make the decision on when to finish the breeding season.
With a gestation length of 283 days, Teagasc has provided a guideline of expected calving dates based on the serve dates, and is provided in the table below:
AI serve date Calving date June 1 March 11 June 15 March 25 July 1 April 10 July 15 April 24 August 1 May 11
Every farm is different, and the same scenario doesn’t suit all farms, however, most dairy farmers should aim on concluding their breeding season between 1 July and 15 July to have calving well wrapped up my mid-April.
The removal of late calvers, cows calving down early and ensuring a shorter calving interval will have a positive impact on farm profitability.
The knock-on affect of this is that your calf value will be increased as late calves will be valued lower and are associated with having more health problems.
Additionally, late calving cows won’t have a lot of time (~ four weeks) to recover before breeding next year, which will hinder their chances of going back in-calf.
Monitoring activity
Identifying cows in heat can be quite straight forward during the first round of breeding as a number of cows come into heat together meaning activity and mounting is frequent.
This activity takes a drastic drop-off as the second round of the breading season kick in, with an average of 40-50 mounts in the first round to 10-15 mounts during the second round.
As the cows are harder to identify and it might require too much time to be constantly monitoring the activity yourself, there are a few options to help with this as follows:
- Introduction of a teaser bull;
- Keeping tail paint topped up;
- Using bulls but continue to AI;
- Heat detection systems/collars.
If you plan on putting out the bull soon or have already done so, it is important not to forget how many cows a bull can serve to make sure every cow goes in calf.
Bull numbers
A mature stock bull should be able to cover about 30 cows within three weeks, which means the bull will be serving about 1.4 cows/day.
If there are a lot of repeats or more cows that are coming into heat in the next few weeks, the bull will more than likely be overworked. This can have a serious impact on your breeding season.
The number of bulls needed is going to vary throughout the breeding and Teagasc has provided a table showing the number of bulls needed in a 100 cow herd throughout breeding, as follows;
Breeding cows Submission Rate Conception rate Cows in calf Cows not in calf Mature bulls required Week 0 100 100 5 Week 4 100 90 55 50 50 3 Week 7 100 90 50 73 27 2 Week 10 100 90 50 85 15 1
In the above scenario, artificial insemination (AI) is bring used in the first round with good results all round, meaning using three bulls will be enough.
Where there are days with loads of cow activity, you shouldn’t rely solely on the bulls and artificial insemination should be used in conjunction with the bulls.
Bulls should not be overworked and should get a day off every now and then, in order to keep them keen when running with the cows.