EARLY REPRODUCTIVE CHARACTERISTICS OF LEGHORN PULLETS REARED ON LEAST-COST DIETS FORMULATED TO PROTEIN AND/OR AMINO ACID SPECIFICATIONS

Abstract

Leghorn pullets were reared on one of four dietary programs formulated to (1) conventional least-cost, (2) least-cost to amino acid requirements with no specification for crude protein, (3) as (2) with cost of protein feedstuffs increased 40% and (4) corn-soybean meal. All diets contained 18% and 15% CP, or equivalents, for 0–6 and 6–18 wk, respectively. Diets were offered ad-libitum to 14 replicate groups of 10 caged pullets. Pullets fed the conventional least-cost and corn-soybean diets were heavier (P < 0.05) at 6 wk of age than pullets reared on either of the two diets formulated to amino acid specifications. At 12 and 18 wk of age, conventionally fed birds were heavier than pullets fed amino-acid-based diets, while all groups were heavier than birds fed the corn-soybean diet. To 28 wk of age, pullets reared on amino-acid-based diets under conditions of elevated protein prices, produced more eggs (P < 0.05) relative to pullets reared on treatments 2 and 4. Results confirmed that pullets can be reared on diets formulated without crude protein specifications, and that substantial use of synthetic amino acids is not detrimental to growth or early reproductive performance. Key words: Pullet growth, amino acid formulation