eOrganic author:
Dr. Jacquie Jacob Ph.D., University of Kentucky
Introduction
The nutritional requirements of growing chickens depends on growth rate, and they are the same regardless of the management system in use. Organic poultry production, however, typically results in slower growth rates—especially in pasture production systems. Most commercial chicken meat production in the United States involves fast-growing strains that require a high density diet to optimize live weight gain and feed conversion. Unfortunately, this has been known to cause metabolic disorders such as ascites and sudden death syndrome. Improved flock management practices have dramatically reduced the incidence of both of these metabolic disorders, which are now seen more commonly at high altitudes.
Slowing growth early will reduce the occurrence of such health problems without compromising final body weight. Chickens are able to compensate for the slower early growth and reach the same final body weight at the same time as they would have with no reduction in early growth. A medium-density diet with optimal protein and amino acid content can be used to maximize lean meat production, but live weight and feed conversion will be negatively affected. Cost per lean meat in this scenario would be optimal. A low-nutrient diet results in lower live-weight gain and higher feed conversion, but cost per live weight may be optimum.
Nutritional requirements of meat-type chickens generally decline as the chickens get older. Most commercial broiler companies feed multiple feeds (each with different nutrient levels) in an attempt to match feed composition and the nutrient requirements of the flock. Typically starter, grower and finisher feed are given. For each producer, the number of feeds used is limited by economic and logistical factors including feed mill capacity, transportation costs, and farm resources. It is not essential that multiple feeds be used, as it is possible to raise meat chickens using a single diet.
Whatever feeding program is used, it is important to meet all the organic regulations. The use of synthetic methionine is restricted, which may require modification of the diet in order to meet the methionine requirements of the flock. When a poultry flock is raised outdoors, the increased activity may result in a slightly higher dietary energy requirement. This should be kept in mind when preparing the outdoor access area.
Slower-growing Strains
Nutritional requirements used for commercial poultry production were developed based on the recommendations of the National Research Council (NRC, 1994). The recommendations, shown in Table 1, are based on research completed before that time. Much has since changed in the genetics of chickens being grown, and the breeder companies have developed requirements specific for the genotypes they have developed. Since the NRC (1994) requirements were developed for slower growing strains of chickens, they may be more applicable to the slower-growing strains of chickens being developed for use in alternative production systems.
Table 1. Nutrient requirements of meat-type chickens (broilers), based on a diet containing 3200 kcal ME/kg or 1455 kcal ME/lb.
| NUTRIENT | STARTER | GROWER | FINISHER |
| Crude protein, % | 23 | 20 | 18 |
| Methionine, % | 0.50 | 0.38 | 0.32 |
| Total sulfur amino acids, % | 0.80 | 0.72 | 0.60 |
| Lysine, % | 1.10 | 1.00 | 0.85 |
| Calcium, % | 1.00 | 0.90 | 0.80 |
| Available Phosphorus, % | 0.45 | 0.35 | 0.30 |
| Linoleic acid, % | 1.00 | 1.00 | 1.00 |
Source: National Research Council
References and Citations
- Leeson, S. 2010. Nutrition and health: Poultry. Feedstuffs 82:46—53. Available online at: http://fdsmagissues.feedstuffs.com/fds/Reference_issue_2012/Reference_issue_2010/08_Nutrition_Health%20Poultry.pdf) (verified 15 Jul 2014)
- National Research Council. 1994. Nutrient requirements of poultry: Ninth revised edition. The National Academies Press, Washington, D.C. Available for purchase online at: http://www.nap.edu/catalog.php?record_id=2114 (verified 15 Jul 2014).
