Actual growth data

This is one of the most powerful of the features of the EFG Broiler model. It is a diagnostic feature, which informs the user whether or not the bird has been able to achieve its potential on each day of the growing period, and what the consequences have been in terms of carcass fatness in achieving that rate of growth. Where the potential is not achieved, the diagnostic facility describes, cryptically, the factor(s) causing the growth of the broiler to be lower than the potential for that day. By interpreting the cause of the constraint to potential growth, the user is able to identify methods by which the growth of the bird may be improved.

If the flock consists of both male and female birds, then these values are shown separately for each sex. If the flock consists of birds of only one sex, then only the columns for that sex are visible.

• 1st Lim. A.A.
  The most-limiting amino acid (based on the biological value of the feed protein being offered and the requirement of the bird at that stage of growth). This amino acid may not always limit growth rate, but will be the amino acid responsible for determining the desired food intake to satisfy protein requirements.
• Pot. attained?
  Indicates whether or not the bird has been able to achieve its potential growth rate on that day
• Excess fat?
  Whether the bird has had to overconsume energy in an attempt to consume sufficient of the limiting amino acid, and hence become fatter than the genetically-determined degree of fatness
• Lim by heat loss?
  Whether the environment was too hot to allow the potential growth rate from being achieved on that day
• Lim by bulk?
  Whether Bulk limited growth rate on that day
• Lim by space?
  Whether Space limited growth rate on that day
• Energy limiting?
  Whether dietary energy was limiting growth rate on that day

In order to interpret this diagnostic output, it is necessary to be aware of the way in which the EFG Broiler model calculates voluntary food intake, given the genotype, current state, food composition and the environment in which the bird is kept. The requirements of the bird for each amino acid are calculated and compared with the concentrations of these in the food being offered. The most limiting amino acid is calculated, from which the desired food intake for protein may be found. A similar process allows calculation of the desired food intake for energy. The greater of these amounts defines the desired food intake of the bird. This is then compared with the amount of the given food the bird is capable of consuming, given the bulk of the food and the environmental conditions being imposed.

If an amino acid is the limiting nutrient, the bird will over consume energy (Exc) in an attempt to obtain sufficient of the limiting nutrient, which it may (Equ) or may not (Lim) be able to achieve. This over consumption of energy will cause the bird to deposit more fat than is desired, thereby increasing the lipid index. If the bird cannot achieve the desired food intake, the limiting factors may be bulk (Yes) or heat (Yes), or both. (For a more complete description of the theory of food intake regulation used in this model, see Emmans, 1981 and 1989).