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Reducing age of slaughter in beef cattle

Reducing age of slaughter in beef cattle

Dr. Peter Lawrence, Teagasc Tinahely, discusses strategies for farmers to reduce greenhouse gas emissions by lowering the slaughter age of cattle through improvements in genetics, nutrition, and health.

Many farmers are aware of the Irish Governments Climate Action Plan and its strategies to reduce green-house gas emissions (GHG) in Agriculture by 25% from the reference year of 2018 to 2030. One of the main contributors to GHG emissions in agriculture is enteric fermentation from the digestive process in our ruminant animals where methane gas is released. Consequently, one of many measures to reducing methane is to reduce the average age of slaughter in our national cattle herd. Currently the average age of slaughter in Irish steers is 26 months of age. The target is reduce this down to 22-23 months by 2030. It is estimated that for every one-month reduction in the national average age of slaughter the reduction is equivalent to the emissions from approximately 100,000 cows.   

In this article I will discuss three main areas where farmers should focus on to improve the animal performance of their beef system and help achieve a reduction in cattle slaughter age without necessarily increasing production costs or lowering carcass weights.


Genetics has always played a key role in helping farmers select cows and bulls that produce more profitable and efficient animals. There is a lot of work being done between ICBF and Teagasc in developing Breeding Indexes to help farmers produce genetically superior and more profitable cattle to meet market and policy demands. Traditionally, breeders were selecting to breed animals destined for slaughter with high growth rates, high carcass weights and carcass conformation.  The recent revision of the beef breeding indexes now include “Age to Finish” as a new trait. This will help suckler farmers and dairy farmers breed beef animals that will be slaughtered at a younger age that are more efficient and less costly whilst not comprising carcass traits. Suckler farmers can choose to breed cows to bulls based on their Terminal Index if they intend selling the offspring for beef or if they intend on keeping the females as potential replacements they should use the Replacement Index. Likewise dairy farmers can now breed cows to bulls based on the Dairy Beef Index to help improve the carcass and beef merits of these calves. Research in Teagasc Grange has consistently shown that cow milk yield is the driver of calf weaning weight and this weight advantage remains with the calf right up to slaughter compared to calves with lower weaning weights. Therefore, suckler farmers should aim to breed from cows with good milk yield or from bulls with good milk traits to maintain or improve the milk yield of their replacements.


Nutrition is important to promote good health in cattle which results in higher productivity and growth rates. Nutrition starts from the beginning of an animal’s life from its first feed of colostrum right the way through to their finishing diet for slaughter. Every effort must be made to ensure that cattle are offered the best feedstuff available. For example, during the grazing season cattle grazing highly digestible young leafy grass with clover will grow better than animals offered stemmy grass which is high in fibre and low in digestibility. Similarly during the winter housing period animals will grow and fatten better and faster when fed high DMD quality silage that is well preserved. So farmers should ensure that they graze cattle on the correct pre-grazing covers (1,200-1,600 kg DM/Ha or 9 to 12 cm in height) during grazing and make high quality silage with an early cutting date (mid-May) for growing and fattening cattle. Also, it is important to feed the appropriate mix and quantity of concentrates to animals fed silage if required to optimise performance and growth. The finishing period of cattle is very important and diets must be balanced correctly for fibre, protein, minerals and vitamins and be high in energy content.


Health and performance of a beef enterprise is dependent on minimising an animal’s exposure to disease and maximising their defence against disease. Farmers should focus on prevention to limit the need for subsequent intervention, particularly with the management of diseases associated with gastrointestinal and respiratory systems (eg. scour and pneumonia). For the new born calf this starts with good hygiene, having well bedded straw lying areas with fresh clean air and no draughts. Colostrum is critical for developing a calves immune system so it is critical that the calve receives a sufficient amount of colostrum immediately after calving. The most common cause of severe scour in calves is associated with rotavirus infection. Annual vaccination of the cow pre-calving with a combined rotavirus-coronavirus and E.coli (K99 and F41) vaccine is an effective way to help mitigate the risk of viral infection.  The causes of pneumonia in cattle is multiple and complex. The main factors associated with susceptibility to pneumonia are stress (disbudding, weaning, mixing cattle), overcrowding, inadequate ventilation, draughts, fluctuating temperatures, poor nutrition, and or concurrent disease. Pneumonia can occur in young and older cattle and vaccination against IBR, RSV & PI-3 will give a broad protection against respiratory viruses. However, vaccination alone is not a replacement for good management, hygiene or bio-security. Internal parasites of cattle such as stomach worms, lung worms and liver fluke can really affect animal performance and thrive is not treated correctly. Therefore, it’s important to keep an eye for clinical signs, take feacal egg samples, get feedback from factories (eg liverfluke) and review the Beef HealthCheck data on ICBF.

The farm vet should always be consulted with specific herd health problems, herd health planning and farm biosecurity.

Finally, trends show that age of cattle at slaughter (suckler & dairy) has been decreasing by 1 week per year in steers and by 1 day per year in heifers since 2011. Average carcass weights for steers is approximately 355 kg and 315 kg for heifers and they have only decreased by 0.5 kg per year for setters but increased by 1.2 kg per year in heifers respectively. With great strides being made in improving animal genetics on farms coupled with better management of grassland, nutrition and health Irish farmers have the potential to reduce cattle age of slaughter and lower GHG’s.