Emerging Reproductive Technologies in Pig Production

Without question, the implementation of artificial insemination (AI) has been the greatest achievement in swine reproductive technology during the last decade. Because AI in swine is not a new technology, the underlining technological enhancements of this procedure are most likely responsible for its recent popularity. It is widely accepted that reproductive performance as a result of AI can be as good and at times better than from the use of natural service. However, the major limitation of AI is the increased number of procedures associated with its use. These procedures are often associated with inconsistent reproductive performance in many herds. Although there are many factors that can effect the outcome of an artificial mating, the aims of this paper are to discuss the reproductive technologies that have had a positive contribution to on farm AI, their constraints to improvement, and the future need and application of new reproductive technologies in this and other areas of swine reproduction. ARTIFICIAL INSEMINATION Semen Analysis and Fertility Assessment One of the advantages of utilising AI is that each boar ejaculate is assessed for some aspects of quality prior to being used in the breeding process. Generally, there are five parameters that are measured to evaluate boar semen quality: visual assessment, concentration, motility, morphology and acrosome integrity. Of these, concentration and motility are most routinely used for sorting ejaculates prior to processing. Measuring semen concentration or total numbers of spermatozoa in an ejaculate does not appear to be a valuable estimate of the overall fertility of the ejaculate (Flowers, 1997), but more so, as a tool to monitor the health an productive output of the boar. However, this parameter serves as the primary feature in processing boar ejaculates for optimising the genetic potential of a single individual. Visual estimation of the percentage of motile and morphologically normal spermatozoa by light microscopy is the most widely used and acceptable method of semen quality assessment. The limitation to this procedure is the accuracy of the generated values. Fortunately, the fact the neither parameters are highly related to fertility and generally a surplus of spermatozoa is inseminated, allows for this inexpensive and relatively simple procedure to be currently used as means to evaluate ejaculates. Currently however, it would seem that to improve the efficiency of a boar ejaculate (produce more doses/collection), an accurate method to determine the number of viable sperm numbers in a dose would be of great benefit. Although Computerized Sperm Analyzers (CPA) are not new, they potentially are the best tools for London Swine Conference The Pork Industry and Public Issues 5-6 April 2001 43 analysing sperm motility and in the near future, morphology. Like visual assessment, the generated results are highly dependent on the operational settings of the equipment as well is handling and care of the submitted sample. The major limitation to the widespread use of CPAs, like other technologies, are costs and repeatability. CPAs can be expensive and although they provide an objective measurement of semen quality, they remain disadvantaged compared to visual assessment because of the extra time required to process samples. The search for in vitro methods and criteria to predict the fertilising ability of semen has been, and will continue to be, the subject of many investigations. It is likely that in the near future diagnostic approaches to assessing the fertility of an ejaculate will be developed in a manner similar to testing samples for pathogens with a simple diagnostic based test (PCR). However a strong correlation to a specific component or characteristic of the sperm cell or seminal fluid to fertility must first be determined (William Flowers, Personal Communication).