Transfer of Polychlorinated Biphenyl (PCB) into Eggs and its Effect on Egg Production and Hatchability

Abstract

Diets containing 0, 10 and 20ppm of polychlorinated biphenyls (PCB), which was a product of a domestic manufacturer and abbreviated as PCB in this paper, were fed to one of 3 lots of 25 egg-type hens each for 6 weeks. Then, dietary PCB was with-drown for another 6 weeks and again the hens were fed the diets containing PCB as in the early 6 weeks in the experiment to collect the eggs for hatchability test at 7th and 8th day of re-feeding. Egg production, average egg weight, feed intake, feed conversion (feed/egg), body weight and mortality were recorded during feeding PCB and after the withdrawal of dietary PCB.Content of PCB in the eggs laid during and after feeding PCB was determined by gas-liquid chromatogratphy. Change in PCB content in the eggs was analysed statistically after transforming the content into natural logarithm.1) Content of PCB in the eggs during feebing PCB increased in proportion to the dietary levels of PCB and to weeks on the diet. The relationship between PCB content in the eggs and weeks (t) on the diet containing 10 and 20ppm of PCB could be described by the following Equations 2 and 3, respectively, y=2.2802+3.0376lnt……(2)y=4.5875+5.5998lnt……(3)where, y is PCB content (ppm) in the eggs and t (6_??_t_??_t) is week on the diet.2) Disappearance pattern of PCB could be separated into 2 stages, i.e., the early stage for one week after the withdrawal of dietary PCB, during which PCB content decreased rapidly and the later stage after one week, during which PCB content decreased slowly. The patterns on the diet containing 10 and 20ppm of PCB could be described by the following two exponential equations 5' and 6', respectively, y=2.503e-2.573t+5.343e-0.129t……(5)'y=5.218e-2.573t+10.238e-0.129t……(6)'where, y is PCB content in the eggs (ppm) and t (t_??_0) is week after the withdrawal of dietary PCB. In these equations, common exponents obtained by covariance analyses of the data were used.3) On the dietary PCB at 10 and 20ppm, no difference was observed in viability of the hens, being 100% on each diet. Little difference was observed on egg production, average egg weight, feed conversion (feed/egg), body weight on each diet. Further experiment will be necessary to confirm these observations.4) Hatchability of fertile eggs laid by the hens on the diets containing 10 and 20ppm of PCB was 42.3 and 23.3%, respectively, which were significantly lower than hatchability of 68.6% of the fertile eggs laid by the hens on the control diet.