Lactational performance of first-parity transgenic gilts expressing bovine alpha-lactalbumin in their milk

Abstract

The goal of this study was to determine whether the presence of the bovine alpha-lactalbumin transgene in first-lactation gilts enhances lactational performance and litter growth. Transgenic and sibling nontransgenic gilts were bred to nontransgenic boars. Litters were standardized to 10 piglets within 24 h of farrowing. Milk production was measured by the weigh-suckle-weigh method on d 3, 6, 9, and 12 of lactation. Bovine alpha-lactalbumin was present in the colostrum and milk of transgenic gilts throughout lactation. The expression of the transgene was associated with alterations in composition of mammary secretions, especially in early lactation. Lactose concentrations were greater (P < 0.05) in mammary secretions of transgenic gilts during the first 12 h postpartum compared with controls. In contrast, total solids concentration in mammary secretions from transgenic gilts were lower (P < 0.05) relative to controls during the first 6 h postpartum. Transgenic gilts produced more milk than controls on d 3, 6, and 9 of lactation (P < 0.01). By d 12, differences in milk production between transgenic and control sows were no longer different. Lactose intake by transgenic-reared litters was greater than lactose intake by control-reared litters on d 6 of lactation (P < 0.05). Total solids intake was significantly greater (P < 0.05) by transgenic-reared litters on d 3 and 6 compared to control-reared litters. The day x genotype interaction on litter weight gain after birth was highly significant (P = 0.011), with transgenic-reared litters gaining weight at a greater rate than control-reared piglets. Expression of the transgene was associated with increased milk production in lactating gilts and increased growth of transgenic-reared piglets. Increased lactose synthesis in response to the presence of the transgene may result in increased milk production in early lactation, leading to increased milk component intake by transgenic litters, and ultimately to increased growth of litters reared by first-parity transgenic gilts.

Animal transgenesis: state of the art and applications

“…Due to the fact that enhanced a-lactalbumin synthesis is closely correlated with an increase in milk production, copies of the bovine a-lactalbumin genes were introduced in swine ( Bleck et al 1998). The results of this work showed an increased milk production during the first 9 days of lactation in transgenic sows, as well as a significant increase in piglet growth rate in transgenic gilts (Noble et al 2002). This effect can easily mean a profit of millions of dollars for the pig industry.…”

Biosynthesis of milk fat, protein, and lactose: roles of transcriptional and posttranscriptional regulation

“…However, excluding a 5% decrease in protein compared with their wild-type counterpart, the insertion had only a minor effect on milk composition (35). Transgenic pigs expressing bovine LALBA had increased milk production with high lactose content (especially during the first 10 days postpartum) and litter growth, without any effects on the proportion of other milk components (140,161).…”

Mammary Specific Transgenic Over-expression of Insulin-like Growth Factor-I (IGF-I) Increases Pig Milk IGF-I and IGF Binding Proteins, with no Effect on Milk Composition or Yield

“…Milk consumption was determined on d3, 7, 14 and 24 postpartum using a modification of the weigh-suckle-weigh method as previously described (Noble et al, 2003). Litters were removed from the sow 1 h prior to the first measurement.…”