Efficient Boar Semen Production and Genetic Contribution: The Impact of Low-Dose Artificial Insemination on Fertility.

Diluting semen from high fertile breeding boars, and by that inseminating many sows, is the core business for artificial insemination (AI) companies worldwide. Knowledge about fertility results is the reason by which an AI company can lower the concentration of a dose. Efficient use of AI boars with high genetic merit by decreasing the number of sperm cells per insemination dose is important to maximize dissemination of the genetic progress made in the breeding nucleus. However, a potential decrease in fertility performance in the field should be weighed against the added value of improved genetics and, in general, is not tolerated in commercial production. This overview provides some important aspects that influence the impact of low-dose AI on fertility: (i) the importance of monitoring field fertility, (ii) the need for accurate and precise semen assessment, (iii) the parameters that are taken into account, (iv) the application of information from genetic and genomic selection and (v) the optimization when using different AI techniques. Efficient semen production, processing and insemination in combination with increasing use of genetic and genomic applications result in maximum impact of genetic trend.

Fertility results of artificial inseminations performed with liquid boar semen stored in X-cell vs BTS extender.

The objective of the present field study was to compare the fertility results for boar semen diluted in X-cell stored up to 4-5 days before artificial insemination (AI) with semen diluted in Beltsville thawing solution (BTS) used for AI following 2-3 days of storage (where the first day being the collection day). A total number of 2601 double inseminations in Norwegian herds were included in this two-trial study. All the boars used in the study were mature cross-bred Norwegian Landrace x Duroc (LD), which were routinely used for AI in Norway. The inseminated gilts and sows were Norwegian Landrace x Yorkshire (LY). The AI doses contained 2.5 billion spermatozoa, and consisted of a mixture of semen from three, occasionally four, boars (i.e. heterospermic semen). Fertility was measured in terms of the likelihood of farrowing and subsequent litter size. The fertility of the semen in both of the extenders was satisfactory and no significant differences were found either in semen stored 4-5 days in X-cell compared with 2-3 days in BTS or in semen stored 2-3 days in X-cell compared with 2-3 days in BTS. The storage capability findings for the long-term extender X-cell could significantly simplify the practical issues of semen production and the distribution of AI doses containing 2.5 billion spermatozoa. However, in pig production systems where all semen is used within 2-3 days, the short-term extender BTS is as good as the more expensive extender X-cell.

A retrospective study on effects of storage time of liquid boar semen on reproductive performance in Norwegian swine.

The objective of this retrospective field study was to determine the effects of storing, for up to 62 h, heterospermic and homospermic semen in the short-term extender Beltsville thawing solution (BTS), on reproductive performance in Norwegian swine of four different breed combinations. The study was based on fertility records after single or double inseminations with semen collected at an AI station in Norway from January 1998 to June 2001. Increasing the duration of storage of homospermic semen, but not heterospermic semen, from an interval of 4-14 h to an interval of 52-62 h, was associated with a 0.5 piglet reduction in litter size. There were differences in reproductive performance among breed combinations that appeared to be associated with duration of semen storage. In conclusion, prolonged semen storage decreased reproductive performance; the extent varied among breeds and was prevented by the use of heterospermic versus homospermic semen.