ANALYSIS OF BIRTH CYCLE IN ALTKLADRUBER A ND LIPIZZAN MARES

The analysis of diurnal distribution of 301 births of Altkladruber Rap pen mares (Slatinany stud, Chek Republic) and 315 births of Lipizzan m ares (Piber, Austria) showed a remarkable similarity of mean time of d ay for birth. The distribution is asymmetrical with an increase during night (maximum at 11 p.m.) and a slow decrease at morning. The variab ility is greater in the fall season then in the spring. Repetition of birth at the same time is not frequent. Correlation of time of birth b etween mothers and daughters does not exist.