The following article has been written by Teagasc.
As the country feels the impact of Covid-19 coronavirus and after a long winter, the breeding season is around the corner.
The last few weeks have been very busy on farms, with cows calving and difficult spring grazing conditions in many areas. However, it is important to focus on the upcoming breeding season.
Setting realistic breeding targets for your farm is the key starting point in developing a plan and managing your herd throughout the breeding season.
From once the cow calves until the start of the oestrus cycle again, is a major factor impacting the reproductive efficiency of suckler herds.
This is usually 60-70 days post-calving for suckler cows or 70-90 days in first-calving heifers.
In order to maintain a 365-day calving interval, the aim is to get the cow back in-calf within one to two breedings after calving.
Teagasc data estimates that for each day that the calving interval extends beyond the target of 365 days, it costs the herd owner in the region of €2.20 per cow per day, mainly in feed costs.
Factors influencing breeding performance
One of the key aspects of running an efficient suckler system is good breeding management and herd fertility.
Cow condition score, bull fertility, the incidence of difficult calving and herd health are some of the main factors that affect fertility in the herd.
Good reproductive efficiency is central to economic and environmental sustainability.
Cows Body Condition Score (BCS)
Body condition score at calving needs be at a herd average of 3.0 for spring-calvers, as this allows for 0.5 of a B.C.S loss up to start of breeding season.
At the start of the breeding season, a cow needs to be on an increasing plain of nutrition with a BCS of 2.5 to give her the best possible chance of going back in calf.
Thin cows that are in poor condition or lose a lot of weight post-calving will have a delayed return to heat.
The effects of low BCS at calving are only partially reversed by placing cows on a high plane of nutrition after calving.
If possible, restricted suckling of calves in the morning and evening (from 4 weeks of age) will help break the maternal bond between cow and calf.
This practice helps improve cow’s/heifers condition coming into the breeding season and cows will return to heat cycle quicker.
A number of infectious diseases are known to affect a cow’s ability to produce a live calf, breed successfully, and subsequently, carry a healthy calf to full-term.
Any issues with herd health need to be checked out fully in consultation with your vet in advance of the breeding season.
Uterine infections can significantly delay the onset of cycling. If a vaccination programme is currently in place, it should be reviewed and updated in consultation with your vet.
A bull’s fertility status can change, from year-to-year. Therefore, it is good practice to have a fertility test carried out on the stock bull, prior to the start of breeding season.
It is estimated that 25% of stock bulls are sub-fertile. Watch the bull working to check he is serving cows correctly. Record when you see a cow being mated and watch for signs of cows coming on heat repeatedly.
If possible, rotate bulls or scan cows early so that an infertile bull or sub-fertile bull can be identified early.
Difficult calving greatly increases the incidence of reproductive problems in the following breeding season and also reduces calf survival.
When selecting sires, a good rule of thumb is to use bulls that are <7.5% on the new calving difficulty rating and high reliability >70% on heifers.
For mature cows, the calving difficulty varies according to breed from 6.2-11.5%, which is available on the ICBF ready reckoner here.