The Prevention of Temperature Shock of Bull and Ram Semen

Abstract

The decreased vitality of ram and bull spermatozoa caused by sudden cooling (cold shock) may be largely prevented by the presence of egg yolk in the dlluent.The activity of egg yolk in preventing cold shock lies in the alcohol-soluble, acetone-insoluble fraction. The phospholipid lecithin may be isolated from this and will prevent cold shock in concentrations as low as 0·12 per cent.The protective action of lecithin for ram spermatozoa is greater at pH 6·5 than at a neutral or alkaline pH.1. INTRODUCTION The collection and storage of semen subjects spermatozoa to numerous environmental changes, which all tend to reduce the number of living and active cells. Sudden changes in temperatwe affect the vitality of spermatozoa; Milovanov (1934) calls the harmful effect of sudden cooling, "temperature or cold shock." Thus, Birillo and Puhaljskii (1936) observed that a fall in temperature from 40 to O°C in 30-60 min caused temperature shock to ram and bull spermatozoa. Cooling over 2 hr caused less shock and if it was prolonged to 3 or 4 hr, cold shock did not occur. However, positive results with ram semen were only obtained with artificially buffered specimens. Gladcinova (1937) reported that rapid cooling of horse, bull, and ram semen from body temperature to 5 or lOoC, caused reduced activity which could not be restored by rewarming. Cooling to 20 or 30°C did little harm. It was also noted that temperatureshocked spermatozoa rapidly died at 37°C.Ram semen was investigated by Gunn, Saunders, and Granger (1942), who found no advantage in slow cooling, but placed the semen in a container at 4°C as soon as collected. A cooling rate of not more than 5°C an hour was recommended by Easley, Mayer, and Bogart (1942) for bull semen, but semen diluted with egg yolk could be cooled rapidly, although sudden cooling to O°C caused significant motility loss. Earlier, Phillips and Lardy (1940) had recommended the use of egg yolk as a protective agent against cold shock and for the storage and transport of semen.Epididymal spermatozoa of the bull and boar have been shown to be very resistant to temperature shock, but after ejaculation the cells have little resistance (Lasley and Bogart 1944;Lasley and Mayer 1944). The addition of egg yolk to the semen before cooling restores resistance.

Phospholipid and Cholesterol Content of Epididymal and Jaculated Ram Spermatozoa and Seminal Plasma in Elation to Cold Shock

“…The addition of phosphat idyl choline (Kampschmidt, Mayer, and Herman 1953;Blackshaw 1954;Blackshaw and Salisbury 1957) to semen after ejaculation is known to increase the resistance of spermatozoa to cold shock. The high concentration of phosphatidylcholine in the plasma of semen from the cauda epididymis may, therefore, be a factor contributing to the higher resistance of epididymal spermatozoa compared with ejaculated cells.…”

“…This causes an irreversible loss of viability which is accompanied by an increased permeability of the cell and, presumably, changes to the cell lipoprotein membrane (Wales and White 1959;White and Wales 1960). Spermatozoa obtained from the epididymis are more resistant to cold shock than ejaculated spermatozoa (Lasley and Bogart 1944;Lasley and Mayer 1944;White and Wales 1961); however, the resistance ofthe latter can be increased by adding phospholipids to semen in vitro (Kampschmidt, Mayer, and Herman 1953;Blackshaw 1954;Blackshaw and Salisbury 1957). It was thought, therefore, that loss of phospholipid from the spermatozoa or seminal plasma in the epididymis might be a factor contributing to the increased susceptibility of ejaculated spermatozoa to cold shock.…”

Effect of the primary cooling rate on the motility and fertility of frozen-thawed rabbit spermatozoa

“…In view of the many potential future uses for cryopreservation of rabbit spermatozoa, it is essential to establish species-specifi c standard protocols. In general, rapid cooling and freezing of semen (cold shock) influences acrosome morphology and the percentage of post-thaw live and motile sperm (Blackshow, 1954;Gilmore et al, 1998;Watson, 2000). To avoid this severe irreversible damage, freezing semen in domestic animals requires a 2-step protocol (primary cooling and freezing) in which samples are suspended in an appropriate extender and gradually cooled from room temperature to 5°C, followed by freezing (Mocé and Vicente, 2002;Barbas and Mascarenhas, 2009).…”

Morphological Changes as Observed by Light Microscopy of the Acrosome of Boar Spermatozoa Subjected to Deep Freezing

“…When spermatozoa are subjected to cold shock they suffer increased acrosome damage (Healey 1969;Pursel et al 1972Pursel et al , 1974Watson and Martin 1972;Visser and Salamon 1974), irreversible loss of motility (Blackshaw 1954;Boender 1968) and increased membrane permeability to stains (Hancock 1951;Dott and Foster 1972). Boender (1968) has demonstrated that the extent of acrosomal damage was determined by the severity of cold shock.…”