Plasma amino acid uptake by the mammary gland of the lactating sow.

Abstract

The objectives of this study were to measure arteriovenous concentration (A-V) differences and estimate uptake of amino acids across the mammary gland in lactating sows. Four sows were used in Trial 1 and nine sows in Trial 2. Cannulas were fitted in the right anterior mammary vein and the carotid artery around d 7 of lactation. Arteriovenous samples were obtained on d 11, 14, 17, and 20. Litters were separated from the sows for 90 min, after which the first blood samples were drawn. Samples were taken at 20-min intervals for the next two consecutive hours. Milk production measurements and milk samples were obtained between d 11 and 19. Liters of plasma to liters of milk ratio (conversion coefficient) was estimated with the Fick method using A-V difference for lysine and milk lysine concentration. The conversion coefficient and the daily plasma flow were 541.41 +/- 35.72 L of plasma per liter of milk and 4,275 +/- 386 L of plasma, respectively. The A-V differences and the plasma flow were used to quantify daily amino acid uptake by the mammary gland. Uptake estimates (grams/day) were 36.51 +/- 4.05 (leucine), 31.24 +/- 3.64 (arginine), 23.39 +/- 2.97 (lysine), 21.22 +/- 1.96 (valine), 18.36 +/- 1.92 (isoleucine), 15.9 +/- 1.9 (threonine), 15.46 +/- 1.58 (phenylalanine), 7.61 +/- 1.12 (histidine), and 6.54 +/- 2.01 (methionine). The uptakes of arginine, leucine, isoleucine, valine, phenylalanine, and threonine significantly exceeded output of these amino acids in the milk. These results indicate that the sow mammary gland retains specific amino acids above requirements for milk protein synthesis.

Arginine metabolism: nitric oxide and beyond

“…The output of proline in the milk of goats [255], sheep [256], cows [257] and pigs [258] greatly exceeds the uptake of proline by the lactating mammary gland, whereas the uptake of plasma arginine by lactating mammary glands greatly exceeds the output of arginine in the milk [255][256][257][258][259]. Studies with lactating mammary tissues have demonstrated arginine-dependent production of proline [249,257], but there was little or no synthesis of proline from glutamate [249] because of the absence of P5C synthetase [47,249].…”

“…As the high content of these amino acids in milk greatly exceeds their accumulation via uptake by the lactating mammary gland [258,265], they must be synthesized within this organ. As in the case of proline synthesis during lactation, arginase also plays an important role in providing substrate for glutamate synthesis in the mammary gland via type II arginase, OAT and P5C dehydrogenase [249,257].…”

Top-dressing 1% arginine supplementation in the lactation diet of sows does not affect the litter performance and milk composition

“…TROTTIeR et al (1997) observed that the level of arginine in sow's milk is smaller than the supply of this amino acid to the mammary gland due to its continue degradation by mammary tissue (O'QUINN et al, 2002). In the present study, crude protein or amino acid content of milk, including arginine itself, were not altered by topdressing L-arginine HCL at 1% supplementation, indicating that despite increasing arginine supply in the bloodstream, level of supplementation was not enough to exceed the threshold of arginine degradation in the mammary tissue.…”

“…Arginine stimulates the secretion of prolactin and growth hormone (ReYeS et al, 1994) and participates in angiogenesis in mammary tissue (MATeO et al, 2008). Due to the effects of arginine on nitric oxide production and vasodilation, this amino acid causes an increase in local blood flow, resulting in higher nutrient supply which could increase milk production (TROTTIeR et al, 1997;WU & MeININGeR, 2000). Furthermore, the possibility of changing the content of arginine in colostrum and milk could reduce the deficit of this amino acid in newborn piglets (WU et al, 2004;KIM et al, 2007).…”

Evaluation of methods used <i>in vivo</i> to estimate the transfer of amino acids and other substrates into the cells of mammary gland

“…Figure 3. The dependence of arteriovenous concentration difference (ca -cv) of ten individual free amino acids in goat's mammary gland on their arterial concentration (ca) for control (+H, infusion of balanced mixture) and experimental (-H, infusion of mixture without histidine) periods (calculated from the data of Bequette et al, 2000) A similar dependence was revealed for mammary glands of sows by defining one regression line of arteriovenous difference for 10 individual amino acids on their arterial concentration using mean values from several measurements (Trottier et al, 1997). The authors pointed out also the absence of any relationship between efficiency of extraction and arterial concentration on combined regression for these amino acids, which is predicted by equation (5).…”