Composition of sow colostrum and milk - The Gestating and Lactating Sow - page 188

9.4.2 Diet and other factors

Effects of diet and environmental factors on total solids content of sow milk have been
reported. Some studies have observed that source of supplemental dietary energy can
affect total solids content of milk (Van den Brand et al. , 2000; White et al. , 1984). Other
studies have found no effect of feeding supplemental dietary energy during lactation in
the form of cornstarch (Coffey et al. , 1982) or animal fat on milk total solids (Coffey
et al. , 1982; Theil et al. , 2004). Feeding crude glycerol (up to 6.77%) to sows tended to
increase milk total solids at day 18 of lactation (Schieck et al. , 2010). Dietary fiber level
during gestation does not affect total solids content of colostrum or milk (Loisel et al. ,
2013). Dietary salt level (0.1 vs. 0.4%) fed prepartum and during lactation affects water
intake by sows, however, does not affect milk total solids at d 18 of lactation (Seynaeve
et al. , 1996). Milk total solids content is affected by ambient temperature, with total solid
percentage being lower at 20 vs. 29 °C (Renaudeau and Noblet, 2001).

9.5 Carbohydrates

Lactose is the major carbohydrate in sow milk. It is also the major osmole in milk. Its
synthesis in the mammary epithelial cell is responsible for drawing water into the secretory
vesicles (Peaker, 1983). Lactose also is considered as the least variable component of milk,
with concentrations typically remaining within a narrow range. Milk lactose content
has a lower coefficient of variation among sows than that of fat or protein (Atwood and
Hartmann, 1992).

9.5.1 Stage of lactation

Lactose concentrations are low in colostrum during the initial few hours postpartum
relative to mature milk (Table 9.2 and 9.3). Concentrations of lactose then increase
gradually over the first two to three days of lactation. This period coincides with the later
stages of lactogenesis (discussed below). This also is the period when activity of lactase,
the major intestinal enzyme that hydrolyzes lactose in the neonate, is increasing (Chapter
15; Le Huërou-Luron and Ferret-Bernard, 2015). Lactose concentrations may decline
in extended lactations of 7 to 8 weeks (Table 9.3), however, only limited information is
available for that period.

Glucose concentration in sow mammary secretions is low (18 to 135 µg/ml; Atwood
and Hartmann, 1995) relative to lactose concentration (27 to 56 mg/ml; Table 9.2 and
9.3). Glucose concentration increases from a low at parturition to a peak at about day
3 of lactation, before declining again through day 5 (Atwood and Hartmann, 1995).
Glucose-6-phosphate increases in concentration rapidly after parturition and remains
elevated through day 5, while glucose-1-phosphate concentrations decline soon after
parturition. Galactose concentration is highest in colostrum and decreases to day 5 of
lactation (Atwood and Hartmann, 1995).