EFFECTS OF SEX-LINKED IMPERFECT ALBINISM (S-AL-S) IN THE CHICKEN ON THE RELATIONSHIPS OF PLASMA-CONCENTRATIONS OF PROGESTERONE AND 17-BETA-ESTRADIOL WITH EGG-PRODUCTION

Effects of the s(al-s) gene for sex-linked imperfect albinism on the r elationships of plasma concentrations of progesterone (P-4) and estrad iol (E(2)) with egg production were investigated during the laying per iod. Egg production of 17 albino and 16 nonalbino hens was recorded fr om 19 to 60 wk of age. blood samples of these hens were taken between 1330 and 1500 h at 19 and 20 wk of age and every 4 wk until 60 wk of a ge. At 61 wk, blood samples were taken 6, 5, and 4 h before a midseque nce ovulation. Plasma P-4 and E(2) were measured by RIA. There was no difference between genotypes in days to first egg (157.8 vs 158.1 d). Hen-day egg production of al binos was greater (P < 0.05) than that of nonalbinos in the 4-wk periods between 52 and 56 wk (83.8 vs 69.2%) a nd 56 and 60 wk (81.3 vs 64.3%). Egg production for the entire laying cycle was not different between genotypes (81.0 vs 73.0%, P = 0.08). P lasma P-4 and E(2) concentrations were not different between albino an d nonalbino hens. From 28 to 60 wk of age, partial correlation coeffic ients between P-4 and egg production, and E(2) and egg weight were sig nificant for albino hens (r = 0.15 and 0.16, respectively) but not for nonalbinos (r = -0.03 and 0.1, respectively), and age and P-4 concent rations were negatively correlated for both albinos (r = -0.22, P < 0. 01) and nonalbinos (r = -0.32, P < 0.01). Preovulatory levels of Pq in albino hens were higher (P < 0.05) than those in nonalbinos. Plasma E (2) was higher in albinos than in nonalbinos 5 h before ovulation (P < 0.05). These data suggest that increased egg production of albino hen s is associated with differences in P-4 and E(2) metabolism.