Evaluating Temperature Effects and Extension Cooling Rtaes on Boar Semen Quality

Abstract

Experiment one examined the effects of temperature variations between semen and extender on eleven different estimates of semen quality. Extender type, short or long term, and time interactions on the quality of semen were analyzed. Eight mature boars (n=8) were collected twice and extended with either Beltsville Thawing Solution (BTS) or Androhep Plus. Nine variations on temperature between semen and extender were resulting from the combinations between 35°C, 37°C or 39°C were examined. Analyses were performed immediately after extension, and at time 24, 48 and 96 h after collection. All data was analyzed using SAS and the proc GLM procedure. Analysis showed that although a four degree Celsius difference occur between semen and extender for two of the samples, samples treatment was not significant (p>.05) for 8 of the 11 estimates of semen quality. Three estimates of mobility significantly affected (p<.05) the two samples with the coolest temperatures of semen, S35/E35 and S35/E37, however the 35°C semen with a four degree difference from the temperature of the extender was not affected. Analysis also showed that Androhep Plus was able to better maintain semen quality at hour 96 as compared to BTS (p>.05), however if BTS at hour 48 had higher values than BTS for semen quality parameters, which is the time in which BTS would be used in a commercial setting. Although BTS and Androhep Plus differed for many of the estimates, values did not fall below rates that have been shown to affect fertility, suggesting that biologically the two extenders would not differ. There were no significant effects of extender on sample treatments (p>.05). The findings of this study negate the rule that semen and extender much be within 1°C of each other before they are mixed together, if between 35°C and 39°C. This could result in time and labor savings during semen processing. Experiment two examined the effects of three rates of cooling on freshly ejaculated semen on eight different estimates of semen quality. Extender type, short or long term and time interactions on the quality of semen were analyzed. Three mature boars (n=3) were tested three times each. Samples were extended with either Androhep Plus, a five day extender, or BTS, a three day extender. After extension samples were cooled at a (1) slow rate, allowed to slowly reach room temperature before being placed in a 17-18°C semen storage unit; (2) a medium rate, immediately place in a 17-18°C semen storage unit; or a (3) fast rate, placed in an incubator set at 12°C for an hour before being placed in a 17-18°C semen storage unit. Analyses were performed on the neat semen at hour 0 and on cooled samples at 4, 24, 48 and 96 hours after extension. All data was analyzed using SAS and the proc GLM procedure. The rate of cooling did significantly differ from one another (p<.05). For all estimates of semen quality, the medium cooling rate and slow cooling rates did not differ from one another (p>.05). Quality estimate for the fast rate of cooling was significantly lower from the medium and slow rates of cooling for motility and mobility estimates. Although the fast rate of cooling had reduced quality of semen, values did not fall below rates that have been shown to affect fertility, suggesting that physiologically the rates of cooling will not differ. Rate of cooling was not significantly affected by extender or time (p<.05). Extender had and time influenced almost all estimates of semen quality. Values were for Androhep Plus were consistently higher than BTS for all estimates of semen quality as time progressed (p<.05). Androhep Plus is a long term extender and contains ingredients better suited for the maintenance of semen quality. Although Androhep Plus and BTS significantly differed, neither saw values drop below what has been shown to affect fertility. This suggests that whether storing semen for a short period or a long period it will not result in decreased fertility for the chosen rate of cooling. The results of these two experiments suggest that boar semen is able to withstand greater temperature fluctuations than previously thought. The first experiment showed that semen and extender do not have to be within 1°C of each other, a goal not easily obtainable in a commercial setting, resulting in saved time and effort. The second experiment showed that there does not have be a holding time before storing semen, which can save time and money during semen processing.