The aim of this study was to describe and compare the effect of different lighting protocols on sexual cyclicity and serum melatonin in domestic female cats. Additionally, anti-Müllerian hormone (AMH) concentrations and ultrasound or histological imaging of the ovaries were included. For this purpose, three experiments (Expt.) were conducted under controlled lighting conditions: Expt. I: A short photoperiod (SP) vs. a long photoperiod (LP), Expt. II: LP preceded by a SP, and Expt. III: Prolonged 6-month SP. In both Expt. I and II LP increased most of the ovarian functionality parameters, prior exposure to a SP did not increase functionality. In Expt. I, AMH serum concentrations did not differ between both photoperiods. In Expt. II, ultrasound ovarian volume and follicle diameters were larger in LP than in SP. Intraovarian arteries' resistance index was lower in LP. In Expt. III, cyclicity was maintained without quantitative differences between the first and the second half. At the end of Expt. III, the ovaries presented a proportion of 92.08% primordial, 2.35% primary, 2.26% secondary, and 3.31% small antral follicles. Corpora lutea also appeared in three queens. In the three experiments, spontaneous ovulation frequency was not influenced by the photoperiod. In both Expt. I and II, serum melatonin concentrations were not different between photoperiods. These concentrations did not also differ at the end of Expt. III. It was concluded that although sexual activity was more intense under this artificial LP, independently of the previous photoperiod, cyclicity and ovulation were maintained under a SP.
Lantermino et al. (Tue,) studied this question.