By systematically following the three steps, an apparent problem can be quantified and put into perspective. If the incidence of a defect is too high, possible causes and solutions can be pinpointed by consulting the section of this book on the defect concerned. Introduction Nutrient check list Nutritional factors are often suspected as a prime cause of problems. If such problems occur, check the following list of nutrients which play an important role in shell quality: Calcium Calcium intake should be between 3.8 and 4.2 g per bird and per day, and be maintained by adjusting the diet formulation or by the use of calcium (sprinkling large particles of a calcium source ‘icing’ on top of feed in troughs), starting 2 weeks before lay. Phosphorus Total phosphorus intake should be below 0.8 g per bird and per day. The ratio of calcium to phosphorus should be as near 6:1 as practical. Vitamin D3 Most custom-made premixes are adequate (2500–3500 IU/kg feed) in this vitamin, but high storage temperatures, long periods in storage and poor mixing may result in deficiencies. Products such as ROVIMIX® Hy•D® might be considered to complement the vitamin D3 supply of laying hens. Magnesium Problems can arise if intakes are greater than 0.7 g per bird and per day. Calcium sources that contain magnesium, particularly dolomitic limestones, can result in magnesium levels that are too high.
By systematically following the three steps, an apparent problem can be quantified and put into perspective. If the incidence of a defect is too high, possible causes and solutions can be pinpointed by consulting the section of this book on the defect concerned. Introduction Nutrient check list Nutritional factors are often suspected as a prime cause of problems. If such problems occur, check the following list of nutrients which play an important role in shell quality: Calcium Calcium intake should be between 3.8 and 4.2 g per bird and per day, and be maintained by adjusting the diet formulation or by the use of calcium ‘icing’ (sprinkling large particles of a calcium source on top of feed in troughs), starting 2 weeks before lay. Phosphorus Total phosphorus intake should be below 0.8 g per bird and per day. The ratio of calcium to phosphorus should be as near 6:1 as practical. Vitamin D3 Most custom-made premixes are adequate (2500–3500 IU/kg feed) in this vitamin, but high storage temperatures, long periods in storage and poor mixing may result in deficiencies. Products such as ROVIMIX® Hy•D® might be considered to complement the vitamin D3 supply of laying hens. Magnesium Problems can arise if intakes are greater than 0.7 g per bird and per day. Calcium sources that contain magnesium, particularly dolomitic limestones, can result in magnesium levels that are too high.
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