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Calf Rearing – Maximising Genetic Potential and Lifetime Performance


Calf Rearing – Maximising Genetic Potential and Lifetime Performance


Heifer rearing is a crucial component of any dairy system. It can determine future profit and sustainability of the dairy farm. There are many factors associated with calf rearing, specifically relating to environment, nutrition and management and there are critical periods in the time from birth to breeding to first calving. From birth to weaning is one of the most crucial periods in terms of development of the calf and future performance.

With calving now started on many farms round the country, calf rearing will become a big part of the daily routine for the next 3-4 months. It’s critical that calves get the best possible start in life, and this can be achieved through optimum intake of good quality colostrum. Following the 3-2-1 rule (3 litres of colostrum fed within 2 hours of birth from the 1st milking after calving) will enhance the calf’s immune system in the early weeks of life. Disease pressure should also be kept to a minimum throughout the busy spring period, with calves housed in clean, dry, well ventilated sheds that are sheltered from draughts.

Achieving target bodyweights is an integral part of rearing replacement heifers. Critical stages, such as weaning and breeding should be based on weight, rather than age. Research indicates that breeding should be completed at 60% of mature liveweight (360kg for a 600kg mature liveweight) and calving at 90% of mature liveweight (540kg for a 600kg mature liveweight). A more economical heifer rearing program can be achieved by reaching these targets earlier, with the aim of calving the heifers at 24 months. Any incidence of disease throughout the first 6 months of life can have significant negative impacts on growth rates, with research showing a decline in growth rates of 8% for calves with pneumonia alone, 18% for calves with diarrhoea alone, and 29% for calves with both pneumonia and diarrhoea.

Growth rates in the first 8 weeks of life have also been shown to have profound effects on milk production later in life. A number of studies from around the world have identified a link between average daily gain in heifer calves from 0-8 weeks of age and first lactation milk yield in the same animals. Results of these studies indicate that an additional 100g/day of average daily gain in the pre-weaning period results in between 225 and 500 litres extra milk in the first lactation.

These well-documented effects of growth rates in young heifer calves on subsequent fertility and lifetime milk production show the critical importance of calf rearing during the next 3 months on Irish dairy farms. The calves born on farms in the coming weeks will have the highest EBIs (Economic Breeding Index) in the herd. Prevention of disease and achieving optimal growth rates in these calves will ensure that this genetic potential is not wasted.

Dr. Michael Reid and Dr. Ian Hutchinson.


Nutribio’s new ImmuBoost Advantage Calf Start is the ideal solution to help you maximise your calves’ genetic potential and to optimise their lifetime performance. For more information, contact us on (021) 4507303 or send us a request form. You can also speak to your rep.