Effect of diluents on motility of ram sperm during storage at 5 degrees C.

This study examined the effects of 5 diluents--glucose-phosphate (GP), skim milk-egg yolk (MY), egg yolk-citrate (YC), blood sera (S), and seawater (SW)--on daily motility of ram sperm stored at 5 degrees C for a short time. Ram semen collected by artificial vagina was diluted. Percentage of motile spermatozoa (PM) was assessed every 24 h up to day 10 after dilution. The different kinds of diluents except for SW had no effect on the primary motility of sperm and the primary motility was 0 with SW. There was a significant effect (p<.01) of diluent type and storage times in the conservation rates after cooling for PM. The GP diluent achieved greater values (80.5+/-0.88%) than S (69.5+/-1.70%) and MY (78.0+/-1.17%), while YC showed an intermediate value (79.0+/-1.24%). In relation to time of storage, GP and YC diluents showed the PM values up to day 10, but these values were 8 and 7 days for MY and S, respectively. The GP and YC extenders maintained a PM > 50% up to day 4, while MY was greater than 50% up to day 3 and S to day 2.

Factors affecting the shape of lactation curves of Holstein cows from the Balikesir Province of Turkey.

The shape of the lactation curve for 475 Turkish Holsteins was estimated by fitting a gamma function to daily milk yields from monthly recording of 754 lactations. Lactation curve traits that were analyzed included a scaling factor associated with yield at the beginning of lactation, the inclining and declining slopes before and after peak yield, DIM at peak yield, and peak and lactation yields. Persistency of lactation yield was measured from 1) the gamma function, 2) the coefficient of variation for monthly test-day yields, and 3) the ratio of lactation yield to peak yield. The log-transformed gamma function explained 71% of variation in daily yield. Effects of farm operation, calving year, calving season, parity, and service period were significant for the various lactation curve traits. Peak and lactation yields were higher for cows that calved in fall and winter, and persistency was higher for cows that calved in summer and fall. Peak and lactation yields were lower, but persistency was higher during first lactation. Repeatability estimates were moderate for peak (0.26) and lactation (0.34) yields and lower (0.06 to 0.20) for other lactation curve traits.