Seasonal changes in reproductive activity, sperm variables and sperm freezability in Blanca Andaluza bucks

Interest in the preservation of endangered breeds such as the Blanca Andaluza goat, has increased and some steps should be therefore taken to ensure it. The study was designed to determine the seasonal reproductive pattern of Blanca Andaluza bucks, and whether this affects the quality of their semen and its freezability over the year. Seven bucks were used and their body weight, testicular weight, plasma testosterone concentration and fresh sperm quality determined every week. The collected sperm was cryopreserved and stored; it was then thawed and the same sperm quality variables measured every fortnight. High plasma testosterone concentrations were recorded during the summer and autumn, and low concentrations were recorded during winter and spring (p<0.001). No differences were seen between seasons in terms of the percentage of bucks ejaculating, the percentage of active bucks, or ejaculate volume. However, the sperm concentration, the total number of sperm per ejaculate, and the values for most fresh sperm variables were lower during the winter period (at least p<0.05). After freezing-thawing, the quality of winter-collected sperm was better, in some respects, than that of summer-collected sperm (at least p<0.05). These results reveal that Blanca Andaluza bucks show seasonal reproductive activity in terms of their plasma testosterone concentration, but no clear change in their sexual behaviour between seasons was observed. The values of fresh sperm variables also vary over the year, reaching their lowest during winter. However, after freezing-thawing, winter-collected sperm is of overall better quality than sperm collected during the summer. Additional key words: endangered goat breed; testosterone; seasonality; fresh semen; cooled semen; semen cryopreservation. Abbreviations used: BW (body weight); LH (luteinizing hormone); LIN (linearity coefficient); STR (straightness coefficient); TW (testicular weight); VAP (average velocity); VCL (curvilinear velocity); VSL (straight-line velocity); WOB (Wobble coefficient); WWS (week within the season). Citation: Gallego-Calvo, L.; Gatica, M. C.; Santiago-Moreno, J.; Guzmán, J. L.; Zarazaga, L. A. (2015). Seasonal changes in reproductive activity, sperm variables and sperm freezability in Blanca Andaluza bucks. Spanish Journal of Agricultural Research, Volume 13, Issue 4, e0403, 10 pages. http://dx.doi.org/10.5424/sjar/2015134-8168. Received: 18 Jun 2015. Accepted: 29 Oct 2015. Copyright © 2015 INIA. This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial (by-nc) Spain 3.0 Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Funding: INIA-CICYT (Spain), Grant RZ2010-00001-00-00 Competing interests: All authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported. Correspondence should be addressed to L.A. Zarazaga: [email protected]