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KMID : 0900920000240040321
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Korean journal of Animal Reproduction
2000 Volume.24 No. 4 p.321 ~ p.333
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Transgenic Alteration of Sow Milk
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Wheeler Matthew B.
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Abstract
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High production of milk and its components are necessary to allow maximal growth of developing piglets. In this study, transgenic pigs were produced containing the alpha -lactalbumin gene, whose product is a potential limiting component in the production of milk. Two lines of transgenic pigs were produced to analyze the effects that overproduction of the milk protein alpha -lactalbumin may have on milk production and piglet growth. Transgenic pigs were produced through microinjection of the bovine alpha -lactalbumin gene. The gene construct contained 2.0 kb of 5′flanking region, the 2.0 kb coding region and 329 bp of 3′flanking region. Sows hemizygous for the trans gene produced as much as 0.9 g of bovine alpha-lactalbumin per liter of pig milk. The production of the bovine protein caused approximately a 50% increase in the total alpha -lactalbumin concentration in pig milk throughout lactation. The concentration of bovine alpha -lactalbumin was highest on day 0 and 5 of lactation and decreased as lactation progressed. The ratio of bovine to porcine alpha -lactalbumin changed during the sow′s lactation. This ratio was 4.3 to 1 on day 0 of lactation, but by day 20 of lactation the ratio was 0.43 to 1. This suggested that the bovine transgene and the endogenous porcine gene were under slightly different control mechanisms. The higher level of total alpha-lactalbumin present on day 0 of lactation was correlated with higher lactose percentage on day 0 in transgenic sows (3.8%) as compared to controls (2.6%) (P＜0.01). Although there was also a trend for higher lactose percentage in transgenic sows on day 5 and 10 of lactation, no significant differences were observed. These data suggest that alpha -lactalbumin is limiting early in lactation of swine. Furthermore, higher concentrations of alpha -lactalbumin early in lactation may boost milk output.
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KEYWORD
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Transgenic swine, Milk proteins, Lactose, Lactose synthase
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