Seasonal Variation and Age-Related Changes in Semen Quality of Limousin Bull in Indonesian Artificial Insemination Center

Abstract

The objective of this study was to determine the effect of season and age on semen quality (individual motility, mass motility, concentration, volume, pre-freeze motility, and post-thaw motility) of Limousin Bull under the tropical condition in Indonesian artificial insemination center. This study used a large data set recorded over eight years (2011 until 2018) of production period (n = 6758 ejaculates, n = 19 bulls) retrieved from Singosari National Artificial Insemination Center. Rainfall and other climatic data were collected from Malang Meteorological, Climatology, and Geophysics Agency, Indonesia. Seasonal effect was grouped into three groups, i.e. rainy season (total rainfall per month >200mm), humid season (total rainfall per month = 100-200 mm), and dry season (total rainfall per month <100). Bull age is grouped into seven groups (2, 3, 4, 5, 6, 7 and 8). Data were analyzed using Mixed Model procedure classifying effect of season and age on fixed effect and bull as a random effect. Season had a highly significant effect on individual motility, pre-freeze motility, and post-thaw motility (P<0.001), and did not have a significant effect on concentration, volume, pH, and mass motility. Individual motility, pre-freeze motility, and post-thaw motility were highest in the rainy season and declined in the dry season. Bull age had a highly significant effect on individual motility, concentration, volume, pre-freeze motility, and post-thaw motility (P<0,001). Bull age did not have a significant effect on mass motility and pH. Two- and three-years old bulls have superior individual motility and concentration. However, it is decreasing at age three until eight years old. The lowest volume was at age two and increased gradually until age eight. Meanwhile, pre-freeze motility and post-thaw motility increased at two to five years old and then declined until eight years old.