The production parameters influencing the composition and structure of pastoral cattle herds in a semi-arid area of Kenya

age bovin calving interval calving rate cattle culling edad effectif du cheptel ganado bovino hatos herds intervalle entre parturition intervalo entre partos kenia kenya livestock numbers mortalidad mortalite mortality parto parturition parturition interval pastoralism pastoralisme pastoralismo performance de reproduction reproductive performance reproductividad saison seasons troupeau