Beef cattle production has never been as progressive or as technical as dairy farming, but that has to change if producers are to continue farming, with reduced, if any financial support post Brexit.

When it comes to the differentiating the top and bottom 25% of suckler cow producers, most experts agree calving interval and age at first calving – figures that not only affect overall productivity but also profit margins – are the two key areas farmers fail to grasp.

Speaking at the British Cattle Breeders Conference in Telford, Professor David Kenny was one of several who stressed the importance of calving down beef heifers at 24months, the same age as their dairy counterparts, to ensure early resumption of oestrous post calving and a extra year of production.

"Despite its obvious critical importance to the financial sustainability of the enterprise, there is clear evidence of suboptimal reproductive efficiency in beef cow herds in both Ireland and the UK," said Professor Kenny.

"National statistics from the Irish Cattle Breeding Federation (ICBF) suggest that, on average, only slightly over eight calves are born to every 10 cows annually, with inter-calving intervals in the region of 400 days overall and approximately 385 days for spring calving herds alone. Similar statistics have also been published recently for the UK by Quality Meat Scotland and the Agricultural and Horticulture Development Board.

"Teagasc studies indicate that this inefficiency is costing Irish farmers in the region of €2 per cow per day – mainly feed costs – for each day calving interval extends beyond the 365-day target – equivalent to €100 per day for a 50-cow herd."

He added that calving heifers at two years of age is key for a reproductively efficient beef cow herd and that only 20% of heifers have met this target in Irish herds in recent years, compared to the national average is 32.5months – figures which are similar to those published for UK herds by ADHB.

Professor Kenny also said that producers should be looking to achieve other key targets such as: <5 % cows culled annually as barren; >95% of cows calving to wean a calf; compact calving with 80% of cows calved in 42 days; replacement rate 16-18%. Furthermore, cows should produce a minimum target of six calves per lifetime with sustained genetic improvement of the cow herd for economically important traits relating to reproduction, calving ability and calf weaning weight and close alignment of calving date with pasture availability.

Achieving such goals is however, dependant on early onset of puberty and breeding of replacement heifers, along with early resumption of heat post calving.

Puberty in heifers, he said is influenced mostly by nutritional status, particularly during early life and body fat reserves, but is also affected by breed. Dairy-bred heifers cycle at a younger age than native beef breeds which in turn are likely to reach puberty before continental beef breeds. Other factors affecting early puberty are season of birth and bull exposure.

Hence he encouraged producers to select heifers for breeding at a young age to ensure target weights of 55-60% of cow weights are met for bulling at 15months of age.

While dairy-bred animals are known to reach puberty earlier than beef-bred heifers, trials have also highlighted that dam breed type does not affect age at puberty, or age at first breeding. Pregnancy rate following breeding for either six or 12-weeks was nevertheless higher for dairy compared to suckler-bred heifers.

Furthermore, heifers sired by an early-maturing breed, eg Angus, were younger at puberty and at first breeding, and had a higher pregnancy rate at six-weeks compared to those sired by a late-maturing Limousin breed. Yet sire breed did not influence pregnancy rate following 12-weeks of breeding.

And, while age at first breeding was earlier for heifers on a high winter feed allowance, plane of nutrition did not affect pregnancy rate following either six or 12-weeks of breeding.

Instead, it has been found that while dietary supplementation of the calf is only feasible, in most cases, after weaning, a number of studies now support the view that accelerated growth during early calf growth influences age at puberty to a much greater extent than later during rearing.

While calving heifers at 24months can prove problematic, so too can achieving a 365-day calving interval from there on in.

According to Professor Kenny, this is more challenging in suckler cows than dairy animals due to her suckling calf which prevents the early onset of heat cycles after calving.

However, work conducted at Teagasc Belclare, showed that short-term restriction of suckling activity can significantly advance the onset of normal heat cycles in suckler cows.

Good success was achieved in both autumn and early calving herds where calves were restricted to once or twice daily access to suckle once they reached about a month of age, through locking calves out in a creep area thereby preventing constant access to the cows, or where facilities and weather conditions allow, turning calves out to a nearby sheltered paddock during the day.

Where this has been practiced, the majority of cows will typically be seen in heat two to three weeks later. Additionally, once a cow is observed on heat, suckling restriction can be ceased.

In addition to reducing the cow-calf bond, studies have established that energy intake of the cow in mid to late gestation, mediated through improved body condition score (BCS), has a positive effect on reducing the interval between calving and the onset of normal heat cycles.

For example, calving the cow in moderate, as opposed to poor BCS, can advance the onset of cyclicity by 1-2 weeks.

Overall, pre-calving nutrition has a much greater effect on the onset of heat cycles, through its effect on BCS and the general metabolic status of the cow, than level of feeding post calving. In other words, if a cow is thin at calving, additional feeding after she calves will have limited impact on shortening the time to when she has her first subsequent heat.

Hence, the key objective is to calve cows in moderate to good condition but not overly fat.

"In beef cows, unlike dairy cows, there is no substantial evidence of a decline in conception rate and typical conception rates of 60-70% are achievable to either AI or natural service, unless there are problems with semen quality, AI technique or bull fertility," said Professor Kenny.

"Conception rates reach a normal level in cows bred at 60 or more days after calving and research has shown that the extent of late embryo/foetal loss is minimal (~5%) after the first month of pregnancy.

"Maintaining cows and heifers on a steady plane of nutrition is important, however, during the breeding season, as fluctuations in feed supply, even for a relatively short term can have devastating effects on conception rates for females bred during that time," he said.

Bull fertility can also be an in issue even in mature animals. Professor Kenny said that while the reported incidence of sterility is generally low (<4%), subfertility, at a consistent level of 20-25%, is much more common in breeding bulls.

Furthermore, there is no guarantee that a bull will retain fertility from season to season or even within a season. It is therefore recommended that farmers observe the mating ability of their bulls and particularly for young bulls, the first cows mated should be pregnancy scanned as soon as possible (from 28 days onwards) after mating.

Numerous bacterial, viral and protozoan pathogens such as leptospirosis, bovine viral-diarrhoea (BVD), infectious bovine rhinotracheitis (IBR) and Neosporosis have also been associated with poor reproductive performance in cattle.