Effects of feeding graded levels of vitamin D3 on egg shell pimpling in aged hens

Pimpled egg shells are one of the various types of egg shell problems in the industry today. In this study, graded levels of vitamin D3 (D3) (0, 138, 275, 550, 2200, 22,000, 44,000, and 88,000 ICU of D3/kg of feed) were fed in a corn-soy ration to Single Comb White Leghorn hens (78 weeks of age), randomly assigned to one of the eight treatments. Feed consumption, egg production, egg weight, egg specific gravity, and pimple score were determined at weekly or biweekly intervals for a 10-week period. At termination of the experiment, calcium, sodium, potassium, and ash content of the uterus and serum calcium levels were assayed. Results showed that a significant (P less than .05) linear increase in pimple score, uterine ash, and serum calcium occurred as dietary levels of D3 increased. Egg production and egg specific gravity were correlated to D3 level in a quadratic fashion. Uterine sodium levels declined with increased D3 in the diet, while potassium values showed no differences. Calcium levels of uterine tissue tended to increase with increased D3. The lowest (0 ICU/kg) and highest level of D3 (88,000 ICU/kg) significantly decreased feed consumption. It was concluded that egg shell pimpling is directly related to level of cholecalciferol (D3) in the diet.