Is lower-spec diet a sensible strategy for poultry producers?

One way to minimise the effects of higher feed prices is to opt for a lower-spec diet. But is this a sensible and cost-effective strategy and how do you avoid the post-peak dip? Independent nutritionist Tony Marangos takes a look

Some egg producers have reacted to the steep escalation in feed prices by feeding a lower-spec diet or opting for alternative ingredients. But going for a more modern smaller breed and feeding a higher-spec diet could make the best saving in feed costs.

Genetically more advanced modern layers have been selected for their feed efficiency in converting feed into eggs. To achieve this, the bodyweight of these birds has been progressively reduced and, as a result, their feed intake and energy requirement for maintenance has also been reduced.

Stress of excess nutrients

Heavier-type birds need more energy for maintenance and can eat excessive and counter-productive amounts of other nutrients if their diet is incorrectly balanced. This excess nutrient intake can lead to egg weight increasing significantly and egg numbers falling.

On top of egg size running out of control, free-range layers will also show stress symptoms, such as feather loss, cannibalism and increased mortality. Loss of feather cover will add to the bird’s discomfort, increasing energy needs and therefore feed intake, exacerbating the problem.

One way to counter this excessive intake of other nutrients is to reduce the density of the diet, with energy and essential nutrients adjusted downwards accordingly. If feed is reduced by 3% across all nutrients, including metabolisable energy, in order to achieve the requirement for energy, the heavy bird will need to eat 121g a day compared with 112g a day for the lighter bird fed the higher-density diet. The lighter bird may also be limited by its physical capacity to eat more of the lower-density and more bulky diet and be unable to sustain optimum performance.

Deriving the necessary feed specifications for these two differing-density diets, assuming a price of £129 for wheat and £290 for soya and using a fixed manufacturing and delivery overhead, the delivered prices for these two diets would mean a daily increase in feed cost for the bird fed the lower-spec diet of just under 0.1p, even though the savings would be about £8/t because the heavier bird eats more.

Although this does not appear significant, the annual increase in feed cost for a 10,000-bird unit would be about £3000. To break even, the saving in feed cost of the lower specification diet would need to be well over £14/t. To achieve such a saving would mean a substantial and ill-advised reduction in feed specification.

Feeding low-density diets, especially as pullets are coming into lay with a low feed intake and with the need to gain weight and lay an egg a day, will result in some less-mature birds going out of lay at or just after peak production and losing bodyweight. This is common and is described as a “post-peak dip”.


Whatever approach you take, a good phase-feeding programme will be necessary to control egg size later in lay, because as the bird ages, its feed intake increases and its egg mass output decreases. Phase-feeding essentially means reducing the protein and amino acid levels of the diet as the bird progresses through its laying cycle.

The two main reasons for reducing these nutrient levels in the latter stages of egg production are to reduce feed cost and to reduce egg size, especially if there is no financial benefit in producing bigger eggs.

Although this is sensible, the timing of these changes is critical and several key factors should be taken into account (see box), such as energy requirements and egg mass output. Each flock should therefore be considered individually before a decision is made to change diets and reduce the level of essential nutrients.

Rather than trying to reduce egg weight when it is too advanced, it is more efficient and sensible to control it as the laying cycle progresses. Cutting amino acid levels and, in particular, protein and methionine to reduce egg weight, rather than limiting its increase, may also lead to the more dramatic effect of reducing egg numbers.

Factors to condider when changing diets

  • Daily feed intake
  • Energy requirements
  • Energy level of the diet
  • Level of production and egg mass output
  • Temperature effects on feed consumption
  • Liveweight and feed intake capacity

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