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Farmers hoping to start calving in early March are now over six weeks into the breeding season, and over 80% of cows put to the bull should be in-calf, CAFRE adviser Dominic Mason told a breeding webinar last week.
Speaking at the last of three similar events, Mason said that if a stock bull is used, it is important to look out for repeats. “If there are too many, you need to ask questions of your bull,” he suggested.
For those yet to come into heat, which could be cows that calved late, were in poor condition at calving, or had twins, there is still the option to put them on to a synchronisation programme to stimulate breeding.
If action is taken soon, it should still be possible to keep these cows within the desired 12-week calving period
Where a cow is only calved 40 days at time of PRID insertion, the likely conception rate is probably only around 30% to 40%, but even if breeding is not initially a success, the cow should cycle again, and be more likely to go in-calf. If action is taken soon, it should still be possible to keep these cows within the desired 12-week calving period.
Embryo
Mason also outlined how farmers can manage cows during the breeding period to reduce embryonic deaths and maximise the number of breeding females settled in-calf.
Up to 90% of suckler cows will have an egg fertilised at every service, but early embryonic death between day five and 35 post-service means conception rates are more typically 70%, he suggested.
Keep cows on a steady diet of good quality grass
It can take up to 42 days for the process of implantation of the embryo in the uterus to be complete, and a pregnancy well established.
“Nutrition and body condition score (BCS) are crucial. Keep cows on a steady diet of good quality grass. Cows should be at BCS 2.5 to 3 when bred,” said Mason.
It is also important to minimise stress when handling cows in early pregnancy, and ideally, thin cows, first calved heifers, and animals with twins, should be kept separate from the main herd for priority feeding. Farmers who scan cows should wait until around 40 days after the end of the breeding period.
Research
The other main contributor at the online event was Dr Francis Lively from AFBI who also emphasised the importance of cow condition. He quoted Teagasc research showing that suckler cows which calve down at BCS 2.5 come back in heat around 43 days after calving. At BCS 1.75, this increases to 57 days. As a result, thinner cows have longer calving intervals.
He suggested that in spring herds, the start of calving should be matched with the start of the grazing season, to help keep costs down and ensure cows are on a rising plane of nutrition.
He also said it was important to know the trace element status of the farm, with Iodine and selenium levels directly correlated to achieving higher conception rates.
Culls
When it comes to selecting culls Lively emphasised there is no room for passengers on a suckler farm, so culls should be selected early. Cows that are dangerous at calving should be top of the list.
When asked if cows over 10 years should be automatically culled, he pointed out that research shows carcase weight peaks in fifth calving cows, and can decline after that. But if the cow is still structurally sound and fertile, there are probably younger, poorer performing cows that should be selected out first.
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