The Derrypatrick Herd is a suckler beef research herd based at Teagasc Grange. The herd mostly comprises Limousin and Simmental crossbreds, with replacement heifers purchased as weanlings the autumn prior to breeding. All heifers and cows are bred to AI, with heifers bred to Angus sires and cows bred to a combination of Charolais, Limousin and Simmental sires.

Michael McManus, Teagasc Grange

This spring 105 cows calved, with 110 live calves, nine sets of twins and four cases of mortality. Average first calving age of heifers in 2020 was 24.1 months. Across cows and heifers, the calving season for the Derrypatrick Herd in 2020 was just over 11 weeks. The six- and nine-week calving rates were 84% and 95%, respectively. The level of intervention required at calving was low, with 63% calving unassisted, 32% requiring slight assistance and 5% requiring veterinary, with the latter being mostly for malpresentation.

Breeding started on 4 May, with 100% of the heifers and 91% of the cows submitted in the first three weeks. Seventy-two per cent of the cows and 58% of the heifers held to their first service. At the time of writing, we are in our eighth week of breeding and a breeding scan is due to take place to determine how long the breeding season will last. To aid heat detection, all cows and heifers are tail-painted every 10 days, and each group has a vasectomised bull which has a chin ball attached.

Like much of the eastern part of the country, soil moisture deficits led to a drastic reduction in grass growth on the farm

The yearlings were turned out the last week of March. They were weighed on 10 June, with average liveweights and liveweight gains since mid-April of 468kg and 1.25kg/day for steers, and 440kg and 1.12kg/day for heifers. They are currently getting 48-hour allocations of grass and are entering covers of 1,400kg/DM/ha. Calves were weighed on 18 June, with average liveweights of 156kg for bull calves and 158kg for heifer calves.

Like much of the eastern part of the country, soil moisture deficits led to a drastic reduction in grass growth on the farm. With the farm cover falling to 550kg DM/ha, the decision was made to introduce grass silage to the cows, with the calves having access to fresh grass in the adjoining paddocks. The replacement heifers and yearling beef animals have remained at grass. With the recent rainfall, grass growth rates have returned to normal and grass silage has been removed from the diet.

Alan Twomey, Teagasc Moorepark

The question often arises whether herds should breed their own replacements or purchase replacement stock. There are many pros and cons to both systems, but one of the perceived drawbacks to breeding your own replacements, is the risk of reducing beef output of the male progeny.

First and foremost, the replacement index is designed not only to identify bulls that will breed animals with high merit for maternal traits, such as milk and fertility, but also progeny with good beef merit, since at least half the progeny will be for beef production. Therefore, 29% of the emphasis of the replacement index is based on terminal traits. In other words, it is designed to maintain or improve the beef merit of your herd while improving maternal traits. The current research experiment on the Derrypatrick Herd is comparing the performance of the progeny of sires divergent in maternal traits.

Only progeny from 2018-born animals have been slaughtered to date

In the Derrypatrick Herd, two bull teams have been chosen to compare progeny performance. The first bull team were identified from high replacement index sires, while also ensuring bulls had a high terminal index value (ie balanced bulls). The second bull team was chosen on the terminal index only and so had much lower merit for maternal traits. To ensure a fair breed comparison was carried out, two bulls were selected within the Limousin, Charolais and Simmental breeds for each of the bull teams. For heifers, two Angus sires were used within each bull team.

Performance to date is very similar between the progeny of the two bull teams, although, progeny from the balanced team were on average 10kg heavier at weaning compared to progeny from the terminal team. Only progeny from 2018-born animals have been slaughtered to date and results show there is no significant difference in carcase performance between the two groups.

Results from the Derrypatrick Herd show that bulls with a high replacement index still have the ability produce progeny with similar output traits to the progeny of bulls selected on terminal traits only.

Advice to herds breeding their own replacements is always select high replacement index bulls at breeding. Herds with good fertility and weaning efficiency should aim to use more balanced bulls, bulls which are high on both the replacement and terminal indices. This will maximise the beef merit of progeny while also retaining heifers with good maternal attributes.

Bernie Earley, Teagasc Grange

Antimicrobial resistance is the ability of bacteria (or microbes) to resist the effects of an antibiotic. Antimicrobial resistance (AMR) is one of the leading health concerns in human and veterinary medicine worldwide. AMR occurs when bacteria change in a way that reduces the effectiveness of drugs, chemicals, or other agents designed to cure or prevent infections. A Teagasc study provides the first detailed information relating to on-farm usage of antimicrobials in suckler beef and artificially reared dairy calves from birth to six months of age.

A total of 3,204 suckler beef calves and 5,358 dairy calves were included in the study.

The highest risk period for disease in the present study was between birth and one month of age

On beef farms overall, 12.7%, 5.7%, 2.9% and 20.4% of suckler beef calves were treated with antimicrobials for disease from birth to one month, one to three months, three to six months, and birth to six months of age, respectively. The corresponding values on dairy farms overall for calves treated with antimicrobials were 10.2%, 5.3%, 1.9% and 14.8%.

The highest risk period for disease in the present study was between birth and one month of age, with approximately two-thirds of all disease events occurring during this time period. The Population Correction Unit (PCU) is a measurement developed by the European Medicines Agency (EMA) and takes into account the animal population as well as the estimated weight of each particular animal at the time of treatment with antimicrobials. A value of 45mg/PCU is indicated as a global estimation for cattle.

In the present study, the mg/PCU was 8.03, 2.70, 1.43 and 7.25 for suckler beef calves for the treatment periods from zero to one month, one to three months, three to six months, and from birth to six months of age, respectively. The corresponding values for dairy calves were 9.74, 3.72, 0.95, and 7.11 mg/PCU. The values of mg/PCU in the present study are very low. Disease prevention through proper nutrition, vaccination, adequate housing, and limiting stressors that compromise immunity are likely the most effective means of reducing antimicrobial use.

Actions to take to keep antimicrobials working:

Orla Keane, Teagasc Grange

Just as AMR refers to the ability of bacteria to avoid killing by antibiotics, anthelmintic resistance refers to the ability of parasitic worms to survive a dose that should kill them. There are currently only three classes of anthelmintics licensed in Ireland for the control of gut worms in cattle. These classes are benzimidazole (commonly known as white wormer), levamisole (commonly known as yellow wormer) and macrocyclic lactones (commonly known as clear wormer).

Recent research from Teagasc has demonstrated that anthelmintic resistance is now common on beef farms in Ireland

Anthelmintics from different classes have different modes of action. However, within the same class, all products share the same mode of action and therefore when resistance develops to one product within a class generally other products in the same class are affected. Recent research from Teagasc has demonstrated that anthelmintic resistance is now common on beef farms in Ireland. Therefore, steps need to be taken by suckler farmers to implement sustainable strategies to manage gut worms and to delay the further development of anthelmintic resistance.

Actions to take to slow the further development of anthelmintic resistance:

David Kenny and Mark McGee, Teagasc Grange

In Ireland, 75% of replacement beef heifers are sourced from the beef herd, either homebred (60%) or purchased (40%). Teagasc data clearly show that rearing heifers to calve at 36 months compared with 24 months of age results in a reduction in net margin per hectare on suckler beef farms of 20-30%.

This is mainly a consequence of the feed costs associated with maintaining a cohort of ‘unproductive’ animals within the herd for an additional 12 months.

In addition to its obvious economic importance, work by Teagasc indicates that older age at first calving increases the lifetime emissions burden of the cow and, correspondingly, the emissions per kg of beef produced through production and digestion of feed, as well as manure management related emissions.

The primary drivers of the timing of sexual maturation in cattle are undoubtedly nutritional management and genetics

Early onset of puberty (by 13-14 months of age) is essential to achieving first calving at 24 months of age.

The primary drivers of the timing of sexual maturation in cattle are undoubtedly nutritional management and genetics. In particular, there is now overwhelming evidence to support the importance of early-life nutrition (prior to eight months of age) in regulating the timing of puberty, with pre-weaning live weight gain having a much larger impact than post-weaning gain.

Indeed, recent work conducted at Teagasc Grange shows that offering heifer calves a high plane of nutrition between four and eight months of age doubled the number of heifers eligible for breeding at the start of the breeding season.

Currently, research at Grange is investigating the effect of improved nutrition on the genetic and biological processes involved in sexual development in the young heifer.

Optimal nutritional regimens can then be formulated to consistently and cost-effectively ensure that a high proportion of replacement heifers reach puberty before the start of the breeding season, a central tenet of economically and environmentally sustainable, seasonal calving, grass-based production systems.