Unlocking broiler potential: essential nutritional insights

Why should feed strategy evolve over time?

If the broiler’s feed intake is not optimised as a result of formulation, feed physical quality and/or management, the animal’s growth will be impacted. If the bird does not eat it will not grow, and everything we do as nutritionists and farmers should be to optimise intake of feed and of course nutrients.

Aviagen is constantly reviewing the amino acid profile, the ratio between the essential digestible amino acids and digestible Lysine. The published profile is considered, ‘balanced protein’.

The nutrient density of the diet must be adjusted according to changes in feed intake if the maximum genetic potential is to be achieved. Put simply, broiler performance = energy + balanced protein. But these parameters are evolving, as genetics are optimised. Feed conversion to market weight is coming down year after year while carcass yield (in particular, breast meat yield) is increasing, meaning the feed consumed will be less but the amino acid intake has to be plentiful to support the lean meat deposition potential. Nutrient density must be considered. Feed strategy therefore must reflect the increase in breast meat on birds.

Getting into the detail: Aviagen trial insight

Aviagen conducts frequent trials to explore new concepts and importantly provide the necessary background for new specifications and advice to customers.

In a recent trial conducted in the UK, 1440 all male Ross 308 broilers were distributed amongst 12 dietary treatments (varying levels and combination of energy and balanced protein) comprising 10 pens at 13 birds per pen. Feed was phased into 0-10 days, 11-24 days, 25-39 days and 40-42 days. Body weight and feed intake were measured by phase and carcass characteristics measured at 41 days.

Responses to energy and balanced protein, the key drivers, were interesting. The maximum response was observed with the lowest energy, highest balanced protein point. When dropping to 10% of global advice for energy following, lowest weight gain was demonstrated. Interestingly, the highest energy with highest protein is not optimal. This combination performs 5% below the lowest energy, highest balanced protein point.

When you stay at 95% of advice in balanced protein, feed intake is lower than at 100% irrespective of energy. Further reduction in balanced protein results in further depressions in feed intake ultimately leading to costly losses in daily gain and FCR.

At the lowest level of balanced protein, finished weight is just under 2 kg at 41 days. Compare this to optimum balanced protein and energy when the trial shows 3.5 kg at 41 days with over 25% breast meat yield.

Feed conversion ratios (FCR) at 100% advice was 1.36 FCR at 2.5 kg. Optimal FCR was found at the highest energy, highest balanced protein zone but this was not in balance with daily weight gain. Deciding on the right FCR and weight targets in a commercial setting will also involve a time consideration something that is possible in light of these growth repsonses to protein and energy.

This sliding scale of performance gives you flexibility depending on which market producers are serving. Consider nutrition like a dimmer switch in the house – you can turn it up and down depending on the result you want. Of course, the result you want will be a factor of input costs (raw material, energy and labour) and the profit defined by margins over the selling price.

Where does sustainability fit in this puzzle?

Sustainability and welfare are often conflated by consumers. Slower growing birds are popular in higher income countries from an animal welfare perspective. However, these genotypes may result in up to a 20-point increase in FCR at the same market weight as the conventional bird. This may not be in alignment with sustainability goals.

Looking from a greenhouse gas and environmental footprint perspective, a faster growing genotype is more efficient – hitting <1.40 FCR. To put this into context, one point saving in FCR is considered the equivalent to freeing up approximately 55,000 ha of arable land!

What about the first ten days?

The most critical time period for performance is the first ten days of life. What happens in the first ten days positively influences the potential weight gain and breast meat yield.

Encouraging chicks to eat is essential in management. If the bird isn’t eating, it won’t grow. 80% of first week chick growth can be attributed to feed texture, brooding temperature, and management. Micropellets are highly palatable and can promote early growth as much as balanced protein in the first 10 days.

Early feed seeds the gut, encouraging the healthiest micro floral profile. Products like PoultryStar® stimulate the immune system and are useful in this time window.

In recent work Aviagen has observed that the benefits of a 10-20% increase in balanced protein above the specifications not only improves first week performance but the effects of diet can be seen on liveweight, 3-4% uplift, at 41 days.

What’s next?

Improving performance put simply: reduce energy by 1% while increasing balanced protein by 3-4%.