Dr. Jacquie Jacob Ph.D., University of Kentucky
Feeding pullets during the growing period can have major effects on subsequent egg production performance—any mistakes made during this period can lead to poor egg production, and it can be difficult to correct these problems once the flock has started laying. The size of the pullets at start of lay will affect egg size. It is important to have flexibility in the pullet diet formulation and timing of diet changes to ensure that the target weights are reached at the right age.
Nutritional requirements used for commercial poultry production were developed based on the recommendations of the National Research Council (NRC, 1994). The recommendations were based on research completed before that time. Much has since changed in the genetics of the egg-laying hen, and breeder companies have developed requirements specific to the genotypes they have developed. Many of the breeders have developed strains specifically for alternative production systems.
The nutritional requirements of growing chickens change as they get older (see Table 1). Many commercial egg producers use four or five diets during the growing period: starter 1, starter 2, grower, developer, and sometimes a pre-lay diet. The number of diets used will depend on availability of the diets as well as storage space. It is not essential that a variety of feeds be used. Many producers use only one or two diets during the rearing of replacement pullets.
The use of a pre-lay diet has been debated for years. The theory is that as the chicken is growing, it is putting down calcium in the bones. When it starts laying, it needs to draw on this calcium for egg shell production. The body's metabolism needs to change rapidly from storing calcium to removing calcium. The pre-lay diet, with a slightly higher calcium content, makes this transition a little smoother.
Table 1. Nutrient requirements of growing replacement pullets (brown egg layers)
|Crude protein, %||20.00||18.25||17.50||16.00||16.50|
|Total sulfur amino acids, %||0.85||0.79||0.73||0.65||0.71|
|Available Phosphorus, %||0.4%||0.44||0.43||0.45||0.48|
|Linoleic acid, %||1.00||1.00||1.00||1.00||1.00|
Source: Hy-Line International (2014)
Note about methionine: The National Organic Program rules (United States Department of Agriculture [USDA], 2000) initially stated that synthetic methionine was a prohibited material for animal diets. An exemption was given to allow the industry to find alternatives. As research continued in this area, the National Organic Standards Board (NOSB) later recommended that, until October 1, 2012, the use of synthetic methionine be restricted—originally to 4 pounds per ton for laying hens, 5 pounds per ton for broiler chickens, and 6 pounds per ton for turkeys and all other poultry. After October 1, 2012, the allowed levels were decreased to 2 pounds per ton for laying and broiler chickens, and 3 pounds per ton for turkeys and all other poultry. For additional information, see the eOrganic article Synthetic Methionine and Organic Poultry Diets
§ 205.603 Synthetic substances allowed for use in organic livestock production.
In accordance with restrictions specified in this section the following synthetic substances may be used in organic livestock production:
(d) As feed additives.
(1) DL-Methionine, DL-Methionine-hydroxy analog, and DL-Methionine-hydroxy analog calcium (CAS #'s 59-51-8, 583-91-5, 4857-44-7, and 922-50-9)—for use only in organic poultry production at the following maximum levels of synthetic methionine per ton of feed: Laying and broiler chickens—2 pounds; turkeys and all other poultry—3 pounds.
This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.