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Seminal characteristics and fertility in stallions

The objective of this experiment was to verify the effect of sperm quality and its relationship to fertility in stallion. The data was obtained from seven farms and included 36 stallions, 1198 mares, 2013 cycles and 3817 services, during three cosecutive breeding seasons. The overall pregnancy rate (P), pregnancy per cycle (P/C) and pregnancy per service (P/S), for each stallion were used as dependent variables. Additionally, the effect of age of mare (<15 or >15 years), mare status (lactating, barren and maiden) on fertility indexes was verified. Stallions with viable sperm counts higher than 1.8 x 10(9), motile sperm not lower than 50% and normals rate higher than 60% (n=20), exhibited better P (86% vs 74% p<0.01), P/C (54% vs 45%, p<0.01) and P/S (28% vs 22%) than stallions in which sperm characteristics above those standars (n=16). The normals rate was correlated to P (0.33), P/C (0.50) and P/S (0.36), respectively. In addition to sperm quality, age and status mares were affected the fertility of stallions. These results led to the conclusion that seminal quality affects equine fertility; however, other factors associated to reproductive management, age and status mares are important in the relationship between semen quality and fertility.

stallion; semen; fertility


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