Calf Health Series: Why feed conversion efficiency is highest during the pre-weaning period

This week, as part of the Calf Health Series, brought to you by AgriLand and Volac, we will examine the area of feed conversion efficiency or FCE (also known as feed conversion ratio or 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 first year of life – when 100g of feed will only give 9g of growth.

Additionally, 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.

FCE – the animal’s relative ability to turn nutrients into growth – peaks during this period at around 50% compared with less than 10% from 11 months to calving.

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 note that liquid milk 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.

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.

To view the full range of Volac milk replacers – the Lifeguard range – justclick here

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.

Improved early nutrition and growth rates are correlated with increased plasma IGF-1, a hormone associated with increased growth rates, and this helps to support increased disease resistance, improved immune response and decreased mortality.

These aspects are all vitally important in terms of development – regardless of whether that calf will become a productive cow in your herd or if it will be reared and finished as beef in an efficient and profitable manner.

Part 1: Calf Health Series: The power of colostrum must not be underestimated
Part 2: Calf Health Series: What should I feed, and how much, for optimum condition?
Part 3: Calf Health Series: Which feeding system is best suited to your farm?
Part 4: Calf Health Series: Hygiene and biosecurity must not be overlooked in the calf house
Part 5: How to provide the perfect environment for calves

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