The focus of the review is to show how the Box-Behnken Design (BBD) could be applied in poultry nutrition research. BBD is a multivariate experimental design which uses less treatment combinations and allows researchers to estimate and optimise processes. Box-Behnken design was used in an experiment to estimate growing broiler requirements for total sulphur amino acids (TSAA), lysine (Lys) and threonine (Thr). In the experiment BBD has shown to be a useful tool in estimating and optimizing nutrient requirements in growing broilers.

Chick quality is dependent upon conditions in the laying house, egg handling systems, and the hatchery. If any of these areas are sub-optimal, chick quality, in addition to hatchability, may deteriorate. Alternative methods to improve chick quality are warranted, especially in chicks from young broiler breeder flocks. Moreover, antibiotic compounds that improve early growth and prevent bacterial infections in broilers are becoming increasingly less available to commercial poultry producers. This paper is concerned with breeder hen nutrition as a means to improve chick quality. Published reports concerned with hen nutritional deficiencies and sufficiencies on progeny performance, rather than toxicities, are primarily discussed. The areas of protein, energy, fat, mineral, and vitamin hen nutrition that impact progeny status are reviewed. Non-nutritional substances (i.e., toxins) that impact progeny when present in the hen's diet are reviewed. Specific ingredients and nutrients fed to hens that influence progeny growth, carcass attributes, enzyme functions, and immunity are discussed.

Betaine, a donor of labile methyl groups, can spare choline and methionine but cannot replace these compounds in poultry diets. Betaine is synthesized from choline by choline oxidase and it can donate methyl groups to homocysteine to form methionine. Physiologically, betaine is one of several compounds used by cells to regulate osmotic pressure. Among the potential benefits of its inclusion in poultry feeds are sparing choline, carcass fat reduction and aiding cell osmoregulation. Some feed ingredients are natural sources of betaine per se. This review considers the metabolism, functions and applications of betaine in poultry.

A major goal of many poultry producers is to attain good flock liveability. Historically, most poultry producers have manipulated environmental conditions and management to maximize bird health. In the past two decades there has been much research into nutritional regimes that improve bird health through immunomodulation. Commercial poultry environments contain ubiquitous micro-organisms that continuously challenge the immune system. Nutritional supplements that enhance immune system function may improve flock performance and be economically advantageous. This paper reviews the literature on zinc-methionine and the avian cellular immune system. Current knowledge of the effects of zinc on many animal models is reviewed and a hypothetical mechanism for the action of zinc-methionine on this system is discussed.