The Use of Ovulated Follicles in Determining Eggs Laid by the Ring-Necked Pheasant

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Abstract
The egg-laying performance of 38 artificially propagated hen pheasants penned separately were observed and recorded. The hens were divided into three groups. Two groups were confined in large pens simulating wild habitat and the 3d was quartered in pens of the type used for breeding purposes by the Wisconsin Conservation Department. The hens were killed at selected intervals so that their ovaries would show most of the advance stages of the involuting ovulated follicle. The egg-laying record was then compared with the ovulated follicles found in the ovaries of each hen. Examination of 93 ovaries from hens that were known to have laid eggs showed that they contained structures which were identified as ovulated follicles whereas the ovaries from more than 100 hens that had not reached the breeding age did not contain similar structures. This led to the conclusion that the remains of ovulated follicles alone can be used to distinguish laying from non-laying hens. A highly significant correlation was found between the number of ovulated follicles and the number of eggs laid by the hens in the three groups. The hens were killed at varying intervals during the laying period and up to 190 days after the last egg was laid. Hens killed during a period less than 100 days after the last egg was laid showed a higher correlation between ovulated follicles and eggs laid than did those collected at greater intervals. The evidence indicates that the lower correlation for hens killed at intervals greater than 100 days was due to the complete resorption of some of the ovulated follicles. When the number of ovulated follicles and the number of eggs laid for each hen were plotted graphically the relationship was found to be essentially linear. From this relation was calculated a regression line and confidence limits for estimating the number of eggs laid from ovulated follicles found. The criterion is reliable for the post ovulation period extending from the laying of the last egg during the current breeding season up to December 31 of the same year. The ovaries of 2 groups of wild pheasants were examined and the number of ovulated follicles was counted. By applying the results obtained from the experimental hens it was possible to determine that the average number of eggs laid by these 2 groups of wild hens was significantly different.

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