New Technology

The Beef and Sheep Technology team at CAFRE are focussed on keeping Northern Ireland’s beef and lamb producers at the cutting edge of technology. Through a “can do” approach we are striving to build sustainable production systems which are simple, able  to make efficient use of inputs such as feeds, fertiliser and labour and have a strong market focus.

Dr Steven Johnston and Dr Norman Weatherup are currently progressing with a range of technology projects within two key development areas

To develop an efficient suckler bred heifer production system which will produce calved heifers at two years of age which are capable of entering the suckler herd.

Key technologies

The College of Agriculture, Food and Rural Enterprise (CAFRE) maintains a suckler herd of 100 cows at it’s 900 hectare hill unit.  Traditionally replacement heifers for this herd were sourced as beef crossbreds from the College dairy herd.  The increasing prevalence of Holstein genetics within the dairy herd rendered these heifers unsuitable due to poor conformation, fertility and longevity. A decision was taken in 2003 that all of the college herds should be self-contained to eliminate any dairy influence and to give complete control of the health status and genetics of heifers entering the herd.

A three-breed rotation, utilising Shorthorn, Aberdeen Angus and Limousin genetics was adopted at the hill farm in 2004. This three way breeding system delivers the optimum amount of hybrid vigour within a closed herd.

Within each breed, sires selected are within the top 25 percent of the breed for growth, 200 day milk and eye muscle area. These criteria should ensure the heifers are genetically capable of reaching target bulling weight by 15 months of age. Furthermore, when these heifers calve down, the higher milk value ensures that they wean heavier calves. The eye muscle area EBVs ensures that the by-product male calves have superior carcases when marketed.

If a single calving period is to be maintained in the suckler herd then replacement heifers must calve down for the first time at either two or three years of age. If a heifer is to calve down at two years of age then she must conceive at 15 months of age. This means that the heifer must be cycling at this stage. As conception rates are lower at the first heat, then preferably heifers should have at least one heat before the beginning of the breeding season. Therefore early maturing breeds or crossbreds are most suited to this system. These heifers require careful nutritional management, particularly during the first winter, to ensure that they reach 380 to 420 KG at bulling. Further information on weight targets is shown in Table 1. Calving heifers at two years of age allows 13 percent more cows to be maintained by the same resources, compared with three year old calving.

Table 1. Weight for age targets for calving heifers at 2 years old at Greenmount Hill farm

The labour requirement for heat detection and individual animal handling can be a significant barrier to the use of Artificial Insemination (AI), particularly in spring calving suckler herds. The use of AI allows for the selection of bulls with specific EBVs to address a range of issues, for example, calving ease, growth rate, milk production or carcase conformation and removes the impact of sub-fertile bulls. The use of heat synchronisation and fixed-time AI technologies completely eliminates the need for heat detection at first insemination and significantly reduces the time and labour required for subsequent inseminations. CAFRE heifers have been mated at 15 months of age using this method for the last three years and only heifers that conceive to the first or second AI are retained for breeding as these animals are the most fertile and will improve herd fertility in the longer term. Typically, conception rates to these two services have averaged 65-70 percent.

AI sires with accurate calving ease EBVs are used. This reduces intervention at calving time which reduces labour costs and improves rebreeding success of the heifers. The current AI Aberdeen Angus bull used on heifers is Edinburgh of the Moss. His genetic potential is outlined in Figure 1. Data from previous calvings are shown in Table 2.

Figure 1

Previous experience indicated that using a bull with average calving ease rather than a top 25 percent calving ease bull cost an additional £22/head in veterinary and labour costs.

Replacement beef heifer breeding and rearing strategies

Synchronised 15-month old heifers showing signs of heat prior to fixed time Artificial Insemination

Table 2. Calving information for two and three-year-old heifers

*In the first year of mating the 15 month old heifers, which would subsequently calve at two years old, two bulls were used through AI. One bull had EBVs which indicated very easy calving and one bull had average values for the breed. The veterinary assistance was required to calve four progeny of the bull with average figures for calving ease. This highlights the importance of selecting bulls with easier calving traits.

The data in Table 2 demonstrates that well-managed two year old calving heifers can produce a calf at two years of age and a subsequent calf at three years of age.

Dr Norman Weatherup
Beef/Sheep Technologist, CAFRE, Greenmount Campus
22 Greenmount Road,
Antrim
BT41 4PU

Telephone: 028 94 426 762
Mobile: 07909 916 438
Email: norman.weatherup@dardni.gov.uk