Transgenic animals are produced by inserting 'foreign' DNA into one cell embryos. The foreign DNA is then able to integrate into chromosomes and subsequently be expressed in all somatic tissues of the resultant individual. This phenomena was initially demonstrated by microinjection of genes into the pronucleus of fertilized mouse ova. Transgenic technology could be very useful for introducing genes into domestic animals and in so doing, have great impact toward improving efficiency of animal agriculture. An excellent example of this in the swine industry is the introduction of growth hormone genes into pigs to accelerate their rate of growth. Unfortunately, microinjection into ova has greatly reduced survival of the embryos. In swine, the survival rate of the embryos was approximately 25 to 35%. Efficiency of producing offspring carrying foreign genes (transgenic) by this technique ranges from 0.04 to 1.7% (Rexroad and Pursel, 1988). However, if the embryo survives, the percentage of offspring expressing the foreign genes or 'transgenes' is much higher, about 17 to 100% in swine. It is therefore important to develop highly efficient methods to introduce genes into swine.

The effects of many single stressors have been reported, but how pigs perform when subjected to more than one or two stressors at a time, as is common in commercial swine production, has not. To study this, 256 Yorkshire Hampshire or purebred Duroc pigs (34.7 " 0.5 kg) were subjected to one of the eight treatment combinations (2 2 2 factorial) of ambient temperature [consant thermoneutral (24o C) or high cycling temperature (28-34o C)], stocking density (.56 m2 or .25 m2/pig) and social group (static group or regrouped at the start of wk 1 and 3) during a 4-wk experiment. The stress of high temperature, high stocking density and regrouping depressed 4-wk ADG by 12%, 16% and 10% (P<.05); and ADFI by 7%, 6% and 5%, respectively (P<.05). Out of a possible 60 stressor interactions for ADG, ADFI and G:F, there were no significant three-way interactions and only six two-way interactions, suggesting the effects of the individual stressors were additive (i.e., the stressors' effects on performance were similar regardless of whether they were imposed singly or in combination). Thus, when pigs were subjected to all three stressors simultaneously ADG, ADFI, and G:F were depressed by 31%, 15%, and 18%, respectively. Stressor additivity was further corroborated by examining the effect of "stressor order," or the number of stressors imposed simultaneously. As the number of stressors increased from 0 to 3, ADG, ADFI and G:F decreased linearly. These data suggest that multiple concurrent stressors affect growth performance of pigs in a predictable fashion (i.e., additively) and indicate that avoidance or removal of a given stressor is advantagous even when other uncontrollable stressors persist.

The emerging view is that sickness in pigs, manifesting as reduced feed intake and lowered lean muscle growth, may result from increased biosynthesis of certain cytokines. University of Illinois scientists (Webel et al., 1997) employed 72 pigs weighing 12 kg to test this hypothesis. The pigs were fasted for 12 hours, and then were given an i.p. injection of 5 µg/kg BW E. Coli lipopolysaccharide (LPS) to induce sickness. Blood samples were obtained at 0, 2, 4, 8, 12 and 24 hours post-injection while the pigs continued to fast. At 2 hours post-injection, plasma tumor necrosis factor-a (TNF-a) was elevated 10-fold. At 4 hours post-injection, plasma cortisol was elevated 6-fold and plasma interleukin 6 (IL-6) was elevated 200-fold. By 12 hours post-injection, all of these metabolites had returned to normal baseline values. However, beginning 2 hours post-injection, plasma urea nitrogen began increasing, and reached a peak (3-fold elevation) at 12 hours post-injection. Plasma levels of nonesterified fatty acids, triglycerides, glucose and a-1 acidglycoprotein (an acute-phase protein) were not affected by the LPS injection.

In today's intensive pork production systems, herd health is a major factor determining the profitability of the business. Among the economically most important diseases in the Midwest are porcine reproductive and respiratory syndrome, pseudorabies, transmissible gastroenteritis, swine influenza and pneumonia caused by Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae. Several studies have evaluated the financial impact of acute outbreaks of these diseases in swine operations (Miller & Kliebenstein, 1985, Mullan et a. 1994, Poulson et al., 1993, Rougoor et al., 1996). However, the predominant problem in many swine operations is a subclinical infection of the herd rather than acute outbreaks of diseases. Infected pigs are not obviously sick or die, but perform poorly. The economic consequences of subclinical infection can be slow growth, decreased feed efficiency, low fertility, increased numbers of abortions and stillbirths, and smaller litter sizes (Baysinger et al., 1997). For farms operating on an 'all in, all out' basis, the difference in weight gain between infected and non-infected pigs can be an additional problem, because finishing pigs do not reach market weight at the same time.

We hypothesized that exposure of swine to fumonisin impairs both specific (B and T lymphocyte) and non specific (T lymphocyte, macrophage) immune function, and that inhibition of sphingolipid biosynthesis is the mechanism of this impairment.

Profitability in the swine industry is based on prolificacy. One measurement of prolificacy is the number of piglets produced per year. To optimize prolificacy and profits it is essential that sows are re-bred as soon as possible after weaning. An extended post-weaning anestrus decreases overall productivity and increases costs of production. A large number of sows undergo prolonged post-partum anovulatory periods. Furthermore a significant number of sows, after having their first litter never return to estrus and are removed from the herd. Many factors influence the duration of the weaning-to-estrous interval including: parity, season, duration of lactation, breed and nutritional status (Kirkwood et al.,1984; Aherne and Kirkwood, 1985; Clark et al., 1986; Dial et al., 1987).

The document which follows summarizes a Center proposal for a National Consortium for Pork Technology and Education. I, along with co-PIs from five other academic institutions, were successful in being one of 35 proposals, from among 461 submitted, selected to develop full Center proposals to be submitted to the Fund for Rural America (FRA).

Eperythrozoon suis is a red blood cell parasite. The disease, eperythrozoonosis, is characterized by four syndromes: (i) decreased reproductive efficiency of sows, (ii) weakness and anemia in baby pigs and increased incidence of enteric and respiratory infections, (iii) delayed production gains in feeder pigs, and (iv) acute hemolytic anemia in feeder pigs. Although this disease was first reported in the United States in 1932, our understanding of this organism and the disease it causes remains largely incomplete.

In intensive pig production systems, piglets achieve only about half their potential growth-rate during a lactation period.

A new endeavor that the swine faculty in the Department of Animal Sciences and the Cooperative Extension Service Animal Systems Team has undertaken is the development of a "Swine" Home Page on the Wo...