Incidence of pregnancy failures in buffaloes with different rearing system

During a three year trial, 380 corpora lutea were found in lactating buffaloes and the ratios of not pregnant buffaloes/corpora lutea (NP/CL) were analysed by chi-square test between: years (1999 vs. 2000 vs. 2001), days open (120 days; DO1 and DO2 groups respectively), January–March vs. April–August calving periods, presence vs. absence of swimming-pool (G1 group vs. G2 group respectively). Data were analysed by chi-square test. NP/CL ratios increased throughout the years (7.53%A vs. 26.32%Bb vs. 41.73%Bc in 1999, 2000 and 2001 respectively) due to a progressive paddock overcrowding and were higher in DO2 groups and during the January-March period. The swimming pool presence was able to reduce significantly the NP/CL incidence (18.01%A vs. 33.14%B in G1 and G2 groups, respectively) with a significant effect only in the April-August period (18.62%A vs. 34.96%B in G1 and G2 respectively). NP/CL ratio, as expression of anomalous oestrous cycle and embryonic mortality, may be proposed as a specific tool for evaluating buffalo welfare