Resumen

OJEDA, PM; MANES, J  y  ALLER, JF. Seasonal variations of reproductive parameters, sperm quality and seminal plasma enzymes in Texel rams. Rev. vet. [online]. 2021, vol.32, n.2, pp.138-145. ISSN 1669-6840.  http://dx.doi.org/10.30972/vet.3225719.

19.

The objective of the present work was to determine the effect of season of the year (photope- riod) on scrotal circumference (SC), testicular weight (TW), testicular volume (TV), serving capacity test (SCT), plasma testosterone concentration, semen quality characteristics and seminal plasma enzymes in Texel rams. This study was carried out at the humid pampas of Argentina (37°45’ S, 58°18’ W; 130 m above sea level). Six Texel young (2 years old) rams were used. Body weight, SC, TW (TW=0.5533 x (L) x (W)2), TV(TV=4/3 x (n) x (L/2) x (W/2)2) (being L=long y W=width of the testicle) and plasma testosterone concentrations were determined once a month and the SCT was performed twice per season of the year. Statistical analyses were carried out through linear mixed models for repeated measures (R Core Team). Evaluation of fresh semen was made twice weekly by four consecutive weeks during each season, starting from the 5th to 8th week (middle) of each season. The higher values (mean±SE; p<0.05) of the SC (33.8±0.6 cm), TW (467.5±15.2 g) and TV (442.3±8.5cm3) were observed in the summer (March). The highest mean number (p<0.05) of total mounts was determined in the winter (21) compared to spring (9). Plasma testosterone concentration was decreasing from summer (January=13.2±2.9 ng/ml) to winter (September=0.13±0.1 ng/ ml). Ejaculates (n=192) were evaluated and the best-quality semen parameters were determined in autumm and winter. The yearly patterns of alanine-amino-transferase and lactate-dehydrogenase showed a significant seasonal variation (p<0.05) with a higher activity during breeding season. On the other hand, concentrations of aspartate-amino-transferase, gama-glutamyl-transpeptidase and alkaline-phosphatase were lower (p<0.05) in summer. In conclusion, results suggest that Texel rams show the highest potential reproductive in the autumm season (decreasing photoperiod) in this latitude.

Palabras clave : ram; Texel; serving capacity; testosterone; semen quality; enzymes.

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