In our fifth part of the ‘Calf Health Series’, which is brought to you by AgriLand and Volac, we will take a look at the area of feed conversion efficiency (FCE) [also known as feed conversion ratio (FCR)], and outline why and how to maximise lifetime performance – by maximising efficiency and health – during the pre-weaning period.

Research has indicated that optimal growth in the pre-weaning phase of a young calf’s life is critical to the overall performance of that animal – be it in milk or beef production.

This type of growth, including: mammary cell development; gut development; immune status function development; and metabolic programming are all key during this pre-weaning period of life.

Before puberty, growth is mainly bone and muscle; however, after puberty, heifers gain more fat relative to bone and muscle, so therefore, they are less feed efficient.

Feed efficiency is very high in the young calf (100g of feed will give 50-60g of growth), but these growth rates drop off dramatically during the eight months of life – when 100g of feed will only give 9g of growth.

Moreover, there is strong evidence to suggest that we have been underestimating what is happening during the pre-weaning period and we have not been feeding accordingly to take full advantage.

Therefore, whether you are rearing a heifer or a high-performance beef calf, opting for higher milk replacer intakes early on results in improved FCE and better growth rates.

Taking this into consideration, there are many factors which farmers must consider in relation to FCE.

The five factors are:
  • Timing;
  • Age;
  • Environment;
  • Feed;
  • Cost.

Firstly, in relation to timing, the milk feeding period is a golden opportunity to maximise growth.

Age is vitally important and must also be considered, as the calf’s ability to use feed efficiently declines as the animal gets older.

Farmers should be aware that liquid milk or milk replacer is more nutritious and digestible than concentrate and, because of this, feed efficiency is highest during the milk feeding period.

We have already discussed how providing the correct housing environment is central for a calf to reach its genetic potential and to avoid stress and health issues; but it is also crucial in terms of FCE.

Environmental stress can have an adverse effect on FCE. Unsuitable, draughty housing – coupled with wet bedding – can result in cold, sick calves. If this happens, it will take more energy from feed to keep calves warm and fight disease; therefore, leaving less energy for growth.dairy calves France cherbourg Transport EU Calf

Moving to the type of feed fed to calves, there are a number of factors which can affect FCE, including both the ingredients themselves and the quantity.

As a rule of thumb, the more digestible, the more efficient and a milk replacer’s digestibility is influenced by the type of protein and fat source used, along with its manufacturing process; it pays to buy milk replacer from a trusted supplier.

Finally, in terms of cost, research shows that the total cost of rearing a heifer from birth-to-24 months was less when feeding milk replacer at a rate of 6L/day, rather than 4L/day.

For example, as part of the research, heifers reared on 6L/day of milk replacer up to two months, were less expensive to produce because those reared on 4L/day had to grow later in life (when FCE is low) to reach the same body weight at first calving.

Monitoring FCE

The best way to monitor FCE is to weigh calves, it is important to set target weights for your calves throughout the first 12 weeks of life.

Doubling the calf’s birth weight by the time it is weaned is crucial. A 40kg calf at birth should weigh at least 80kg at weaning – i.e. it must put on 40kg by weaning or 0.7kg/day.

Weaning calves based on their body weight will help ensure a uniform group of calves at weaning. It also means that post-weaning management will be much easier. Therefore, regular weighing must be carried out through this period, as body size cannot be accurately determined by visual assessments.

Calibrated weighing scales offer the most accurate and simplest method (if set up correctly in a race or crush) to measure body weight.

However, they may not be present on every farm. If this is the case, a weigh-band is an alternative and cheaper option.

Heart girth is closely correlated with weight, so measuring heart girth in centimetres – using a weigh-band – will provide reliable measurements.

All calves should be weighed at birth and at six months at an absolute minimum. Weighing could coincide with another management practice, such as worming or vaccination, for a more efficient use of time and to minimise stress on the calf.

How to use a weigh-band correctly:
  • Restrain the animal securely;
  • Place the weigh-band over the animal’s back just behind the front legs;
  • Pull the weigh-band under the animal’s belly using a reaching hook;
  • Read off the animal’s weight by lining up the reading line with the weigh-band scale;
  • Do not overtighten the weigh-band – just flatten the hair.

More Information

Volac has been involved in young animal nutrition for the past 40 years and is an innovator in this field.

The company is committed to helping farmers make the most of their calves and has developed a range of specialised milk replacers, which are specifically formulated for modern dairy and beef animals.

For more information, contact a Volac representative today, or visit the Volac website by clicking here