Effect of deposition site and sperm number on the fertility of sheep inseminated with liquid semen

Abstract

The effect of the deposition site and the numbers of sperm on the fertility of sheep was tested in a field trial in which 1292 Norwegian crossbred ewes aged between six months and five-and-a-half years from 52 farms were inseminated with liquid semen after natural oestrus. Cervical insemination with 150 x 10(6) and 75 x 10(6) spermatozoa resulted in 25-day non-return rates of 63.7 and 56.1 per cent, and vaginal insemination gave non-return rates of 63.3 and 56.6 per cent, respectively. There was no significant difference between the cervical and vaginal inseminations, but the inseminations with 150 x 10(6) spermatozoa gave significantly higher non-return rates (P=0.004). There were significant differences between the non-return rates for different rams (P<0.0001) and farmers (P=0.0002) but the age of the ewe had no significant effect.

The Norwegian sheep breeding scheme: description, genetic and phenotypic change

“…The efforts with AI led to intensified research to increase the non-return rate (Paulenz et al, 2001(Paulenz et al, , 2002(Paulenz et al, and 2003. One decisive factor has been the establishment of a simple vaginal insemination technique known as 'shot in the dark', making it easier for the farmer to inseminate his own ewes.…”

Duration effect of fresh semen kept in vitro on sheep conception rate

“…Variations in the fertility of rams have been reported after cervical inseminations with fresh semen (Paulenz et al, 2002;Anel et al, 2005) and after laparoscopic inseminations with frozen semen (Eppleston et al, 1986(Eppleston et al, , 1991Maxwell, 1986;Eppleston and Maxwell, 1995). Our current study indicates that fresh diluted semen form Suffolk and Doper rams resulted with 59 and 57% conception rates, respectively (Table 1).…”

Management Factors Affecting Fertility in Sheep

“…It has been reported that variation in fertility of ram ejaculates exists independently of the sperm quality (Choudhry, et al, 1995;Paulenz, et al, 2002). Variations in the fertility of rams have been reported after cervical inseminations with fresh semen (Anel, et al, 2005;Paulenz, et al, 2002), with frozen semen (Colas, 1979;Windsor, 1997;Soderquist, et al, 1999;Paulenz, et al, 2005Paulenz, et al, , 2007 and after laparoscopic inseminations with frozen semen (Eppleston et al, 1986;Maxwell, 1986;Eppleston, et al, 1991;Eppleston & Maxwell, 1995).…”

“…have a great effect on fertility results (Anel, et al, 2005). The significant effect of the farm has been described in several studies (Anel, et al, 2005, Fantova, et al, 1999, Paulenz, et al, 2002.Thus, in order to improve fertility results, handling conditions on farms must be improved, along with more widespread use of AI techniques. The geographical area where the farm is located may also have an influence on the success of AI.…”

“…This could facilitate intact sperm degradation in an exponential fashion . This loss of quality, accompanied by a decline in sperm survival in the female reproductive tract, gives rise to a reduction in fertility and increased embryonic loss (Paulenz et al, 2002). In ovine species, ovulation may take place several hours post-insemination (Cheminau et al, 1992;Romano, 2004) and, consequently, the time that a spermatozoon is able to survive after AI is of critical importance to achieve pregnancy.…”