Resumen de Efecto de diversos factores de explotación sobre el intervalo entre partos de vacas de raza berrenda en negro
S. Álvarez, Carlos Palacios Riocerezo, A. Sánchez Ocaña
173 calving intervals of 90 cows belonging to endangered breed Berrenda en Negro have been analyzed, in order to know effect of age, year and calving season on fertility. Mean interval is 425.14 (+12.63) days, longer than other Spanish breeds kept in similar extensive systems, and similar or shorter than intervals found in some Latin American systems. No effect of age (cows<4 year-old; 5-10 year-old; >10 year-old) has been found, but some years have had longer calving interval, and cows calving in autumn showed the longest interval. Both kind of differences may be due to less feed available in some years in an extensive production system, and in some seasons, in spite of supplementary feeding.
