Effect Of Photoperiodic Changes On Breeding Activities And Weight Of Sex Organs In Cattle Egrets (BUBULCUS IBIS L)

Abstract

Fifty four (54) breeding Cattle Egrets of mixed sexes were collected by random shooting at three sites (Mbodewa in Yobe State, Jebra and Konduga in Borno State) of Northeastern Nigeria. Each bird was dissected and its primary reproductive organs (ovary, oviduct and testes) removed and weighed to determine how the breeding activities affected their weights during pre-laying, laying and post-laying stages of the breeding period. The results showed that mean weights of sex organs increased from the pre-laying to laying stages by 10% and decreased from the laying to post-laying stages by the same proportion. The changes in weight of organs did not differ significantly between sites. There was generally high mean weights of sex organs at laying periods (June –August), from a minimum of 0.6g in March to maximum of 9.9g in July for oviduct, 0.4g to 6.5g in July for ovary and 0.8g to 3.6g for the paired testes. Pooled mean weights indicated 38.1% increase in oviduct, 45% in ovary and 16% in paired testes over the breeding period. The pre-laying, laying and post-laying breeding stages coincided with photoperiodic changes associated with the seasons

Keywords: Laying, ovary, pre-laying, post-laying, weights, photoperiodic changes.

The Zoologist Vol. 5 2007: pp. 16-23