THE ESTROUS-CYCLE OF THE ASIAN AND AFRICA N ELEPHANTS, ELEPHAS-MAXIMUS AND LOXODONTA-AFRICANA - TECHNIQUES TO MONITOR REPRODUCTION OF FEMALES IN CAPTIVITY

During the oestrous cycle, circulating progesterone alternates between high and low concentrations in a 16 +/-2 week cycle, whereas variatio ns in plasma oestrogen concentrations are not clearly interpretable al though there is some indication that they show 3 week oscilaltions oth er data suggest they follow a 15-16 week cycle. Females show no signs of oestrus behaviour in captivity but males show a Fleman-like respons e to females urine which is inversely correlated with plasma progester one concentrations. Pregnancy is associated with a sustained elevation in circulation progesterone concentrations and an increase in total o estrogen and prolatin concentrations during the second half of pregnan cy. The oestrous cycle and pregnancy may be monitored most reliably on a weekly basis by analysis of plasma progesterone (African and Asian) or its urinary metabolite, pregnanetriol (Asian). This is theoretical ly achievable in every zoological park housing elephants and is an ess ential first step in any captive breeding programme.