Diet Specifications for Growing Breeder Pullets
Immature pullets and roosters must be managed so as to achieve the desired uniform weight at the time of photostimulation, which is usually around 22 – 24 weeks of age. Growth and uniformity are influenced by feeding program and, to a lesser extent, by feed formulation. Within reason, it is possible to achieve the desired weight at any age when using diets with a vast range of nutrient specifications.
Nutrient intake is largely controlled by the degree of feed restriction. For example, it is theoretically possible to grow pullets on diets with energy levels ranging from 2,600 – 3,100 kcal ME/kg. In practice, diet energy level is usually within the range of 2,750 – 2,950 kcal ME/kg, although for diets necessarily formulated outside of this range, energy intake can be controlled by adjusting feed intake. It is usually more difficult to maintain uniformity with high-energy diets, since this necessarily implies much smaller quantities of feed being distributed at any one time.
Some type of physical feed restriction is universally used to control breeder growth. The traditional system has been skip-a-day, where, as its name implies, birds are fed only on alternate day. The skip-a-day feed intake will obviously depend upon nutrient density and environmental conditions. Controlled feeding should be adjusted to ensure that birds ate cleaning up their feed on a daily basis within two to six hours. Because different strains of birds have different growth characteristics, then initiation of controlled and restricted feeding must be flexible in order to accommodate strain-specific growth potential.
Whatever system of feed restriction is used, the goals are to obtain a uniform and consistent growth rate through to maturity. Ideally, the pullets and roosters will be close to target weight by 16 – 17 weeks of age, since attempts at major manipulation in growth after this time often compromises body composition, maturity and subsequent reproductive performance.
April 21 2008 08:17 am | Poultry