Feeds, Feeding Standards and Nutrition
Nutrient rules
Poultry need energy, protein, essential amino acids, minerals, vitamins and water. Energy is usually expressed as metabolisable energy; protein as crude protein, but lysine and methionine are the first limiting amino acids. Calcium and available phosphorus are critical for shells and bone. Water is the most limiting nutrient: a bird may drink about twice its feed weight.
Ingredients and standards
Common energy feeds are maize, broken rice and rice bran; protein feeds are soybean meal, groundnut cake, fish meal and sunflower cake; mineral supplements include limestone, oyster shell and dicalcium phosphate. Typical crude protein levels are 20-22% for chick starter, 16-18% for grower and layer mash, 22-24% for broiler starter and 19-21% for broiler finisher. Layers need extra calcium after point of lay. Feed forms are mash, crumble and pellet.
Worked example. Make 100 kg of a 20% crude protein mix from maize (9% CP) and soybean meal (44% CP) using the Pearson square. Soybean meal parts = (20 - 9) / (44 - 9) = 11/35 = 31.4. Maize parts = 68.6. For 100 kg: 31.4 kg soybean meal and 68.6 kg maize, before adding minerals, vitamins and salt.
Traps. Do not mix feeds by volume rather than weight; do not feed layer mash to broilers for fast growth; do not add limestone without balancing phosphorus; and do not ignore aflatoxin in poor-quality maize.