Transgenic alteration of sow milk to improve piglet growth and health.

There are many potential applications of transgenic methodologies for developing new and improved strains of livestock. One practical application of transgenic technology in pig production is to improve milk production or composition. The first week after parturition is the period of greatest loss for pig producers, with highest morbidity and mortality attributed to malnutrition and scours. Despite the benefits to be gained by improving lactation performance, little progress has been made in this area through genetic selection or nutrition. Transgenic technology provides an important tool for addressing the problem of low milk production and its detrimental impact on pig production. Transgenic pigs over-expressing the milk protein bovine alpha-lactalbumin were developed. alpha-Lactalbumin was selected for its role in lactose synthesis and regulation of milk volume. Sows hemizygous for the transgene produced as much as 0.9 g bovine alpha-lactalbumin l-1 pig milk. The outcomes assessed were milk composition, milk yield and piglet growth. First parity alpha-lactalbumin gilts had higher milk lactose content in early lactation and 20-50% greater milk yield on days 3-9 of lactation than did non-transgenic gilts. Weight gain of piglets suckling alpha-lactalbumin gilts was greater (days 7-21 after parturition) than that of control piglets. Thus, transgenic over-expression of milk proteins may provide a means for improving the lactation performance of pigs.