The Influence of Dietary Ingredients, Photoperiod, and Cage Density on Egg Shell Pimpling

Experiments were conducted to determine if the degree of eggshell pimpling could be altered by manipulating dietary ingredients, photoperiod, or cage density. In Experiments 1 through 4, treatments consisted of calcium levels ranging from .09 to 5.5%, phosphorus .32 or 1.0%, sodium bicarbonate .25%, chlorotetracycline .55 g/kg, and vitamin-mineral premix fortified at 1.5 times the control level. In Experiment 5, hens were fed diets containing 3.5, 3.75, or 4.5% calcium for the first 11 months of production. In Experiment 6, hens were housed 1 or 3 per cage and received either a 15- or 18-hr photoperiod. Eggshell pimpling and specific gravity values were determined at weekly intervals. Reducing dietary calcium levels from 3.5 to 2.0, 1.0, .50, .25, or .09% for 7 or 10 days numerically or significantly lowered average pimpling scores within 1 or 2 weeks; however, pimpling returned to control values shortly after dietary calcium level was restored to 3.5%. Dietary calcium levels of 3.5, 3.75, and 4.5%, fed during the first 11 months of production had no influence on pimpling. Cage density, photoperiod, dietary phosphorus, sodium bicarbonate, chlorotetracycline, or higher levels of vitamin-mineral premix, had no consistent influence on eggshell pimpling or specific gravity. Eggs with severe pimpling had significantly lower specific gravity than eggs with little or no pimpling. It was shown that the degree of pimpling can be significantly decreased by short periods of calcium deprivation. However, the beneficial response is only temporary. It was also shown that dietary calcium levels had no influence on the degree of pimpling as the hen aged.