What is the interest of formulating turkey feed according to the ideal protein concept?

The growth performance of turkeys has improved hugely for the past thirty years, mainly because of an ever more accurate evaluation of their nutritional requirements. Why is it important to provide optimal protein and amino acid ratios in order to support the growth potential of current turkey strains?

Why has the average performance of current turkey strains so much increased?

The average growth performance potential of turkeys has increased over recent decades, mainly due to genetic progress. In the French context of commercial production, which mostly specializes in medium strains, Daily Gain Weight rose from 80 g/d in the 90s to 121 g/d in 2016. As shown in chart 1, the average weight of commercial turkey males currently revolves around 15.3 kg at 130 days old while 25 years ago, the average slaughter weight was 10 kg at 106 days old (data drawn from AVIPERF^® TECHNA database). In other words, in the past, turkeys were slaughtered at 10kg (1992) and now, they are slaughtered at 15 kg (male weight). Therefore, nowadays, turkeys are slaughtered at a much heavier weight than 20 years ago. In order to cope with this evolution, the share of protein and amino acids supplied by turkey diets must absolutely match these higher requirements.

What are the benefits of formulating feed according to the ideal protein concept?

Protein is well known to have a major effect on growth performance, and this especially applies to the supply of amino acids. Lysine and methionine are the most limiting amino acids in commercial corn soya-bean diets. Threonine, valine and isoleucine are the next most limiting amino acids. In addition, the relationship between the various amino acids has a major impact on turkey growth. In other words, feeding higher levels of one without consideration of the other may result in an amino acid antagonism which can limit growth. Usually, lysine is used as the amino acid reference point in order to express all other essential amino acids relative to the lysine percentage: this is what is referred to as ‘the ideal protein concept’.

This concept relates more precisely to the exact balance of essential amino acids required in order to meet an animal’s needs. The contribution of feed should be neither excessive nor lacking, and it should not be used for energy purposes. As the cinetic of tissues varies with age and their proportion changes, it is admitted that ideal protein ratio usually evolves throughout an animal’s growth cycle.

As the requirements of animals increase due to genetics or other factors, this concept is often used to provide turkeys with balanced essential amino acid diets depending on the lysine requirements.

Formulating feed according to the ideal protein concept allows for lower protein level in diets which can help maintain good breeding conditions. Indeed, high levels of protein are likely to cause wet litters resulting in serious issues such as footpad disease, breast blister and overall poor performance. Reducing dietary Crude Protein content by formulating according to amino acids needs can also have economic and environmental benefits.

Effect of lysine and protein levels on heavy turkey starter-grower period

A trial was run to examine the impact of two lysine levels (1.41% VS 1.31%) combined with two different protein levels (24.57% VS 22.43%) on BUT 6 male turkeys’ feed intake, growth and water consumption during the starter-grower period (until 48 days old). The higher level of protein and lysine was fixed according to TECHNA nutritional standards. It was then compared with lower lysine and protein levels.

The group fed higher levels of lysine and protein achieved the best performance at 48 days old. This result suggests that the ratios of amino acid to lysine in the groups fed low protein diets were not optimal. These findings confirm the interest and relevance of TECHNA nutritional standards within the context of this trial. In addition to these trials, it is important to remind that amino acids needs usually differ depending on the objective sought by producers in terms of profitability. Therefore optimum diet formulations and feeding schedules must be tailored to each specific case.

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