Diet and timing can help get heifers in calf

Producers may be doing everything right to get heifers to the correct calving weight at 24 months, but this means nothing when stock are failing to get in calf.

Calving at two years is the most cost-effective system for rearing heifers, with work carried out by Kingshay showing it costs £183 a head more to calve at two-and-a-half years compared to two years, says Kat Bazeley, Synergy Farm Health.

“However, two things delay age at calving; size and failure to get heifers pregnant.”

For example, although producers may get heifers bulling at 15-16 months and plan to calve at two years, they may not actually calve until 27 months, meaning it’s taking three months to get stock in calf.

“NMR figures for 2009 show that, on average, heifers are calving for the first time at about 29.4 months,” says Ms Bazeley.

And oestrus detection is one of the biggest problems, particularly on larger units, according to Maarten Boers from The Livestock Partnership.

Oestrus Detection

“Because heifers are often away from the main farm, bulling animals are frequently missed,” says Mr Boers.

Dawn and dusk are the best times for heifer heat observation as this is the time when animals are quiet and bulling individuals can be easily seen, adds Kingshay consultant Rob Mintern.

“Heifers generally show obvious signs of heat so should be easy to spot, but tail paint or a cheap emulsion act as good heat-detection aids, with oestrus scratch cards tending to be the best as they are not affected by weather.”

Synchronisation can also be an effective tool for getting heifers in calf and achieving a condensed calving period, says Mr Boers. “There are pros and cons associated with synchronising heifers with hormones, but this method can reduce labour for oestrus detection and reduce costs.”

In block-calving systems, calving heifers before the main herd could also allow more focused management. “However, although synchronisation is good, visual observation will always give the best results,” he says.

Service

And, once heats have been observed, using AI or sexed semen on heifers is a must, says Mr Mintern. “Replacements provide the opportunity to improve genetics in your herd, but many farmers are taking the easy option and chucking the bull out with youngstock, preventing them from assessing and selecting individual animals.”

Timing of service in heifers is also essential to ensure animals hold to service, he says.

“During periods of prolonged hot weather, service should be avoided where possible because, although heifers may express heat, there is an increased chance they won’t hold to service.”

Although delaying service may not be possible for those looking to produce a flat profile, it may be worth modifying management accordingly. “Where sexed semen is being used on heifers, consider using conventional semen instead during periods of extreme weather, so you are not investing as heavily,” Mr Mintern says.

Nutrition

When it comes to fertility, cover all bases to increase the chance of an animal getting in calf, says Christine Pedersen from The Dairy Group. “Heifers are all too often the forgotten group, but it is essential any animal is rationed according to stage of life.”

Heifer rations should be formulated for specific energy and protein levels to get the optimum performance, without wasting inputs.

“Insufficient energy supply can have huge consequences on fertility rates. In the worst-case scenario, an energy-deficient heifer will fail to ovulate, but she is more likely not to show signs of oestrus – reducing heat detection rates and lowering conception.”

As a result, adhering to the basic principle of serving stock on a rising plane of nutrition will increase the chance of getting animals in calf.

It is worth getting forage analysed, particularly when there has been a problem with copper and selenium levels in the past, says Mr Mintern. “Forage quality on heifer grazing land is often ignored. I often see deficiencies in selenium, copper and iodine, which can impact on heifer health and fertility.”

Case Studies

Mary Cook, Taunton, Somerset
Mark Roach, Aldford, Chester
Peter Mills, Sutton Manor Farm, Winchester