Agriculture Reference
In-Depth Information
ingested and digested. Milk is rapidly removed from the gland during the few seconds
in which milk ejection occurs (Brooks and Burke, 1998), and quickly forms a curd once
it enters the piglet's stomach. The milk components in the stomach must be passed into
the intestine and mostly digested within 45 min in preparation for milk from the next
suckling. The initial substrates that went through the complex cellular processes of
synthesis of lactose, fat, protein, and other milk components to a great extent are digested
and absorbed into the piglet's blood in less than a couple of hours after being synthesized.
This chapter focuses on composition of colostrum and milk of the sow, specifically the
content of the many components found in these mammary secretions. Estimates of the
concentration of components in colostrum and milk are affected by a number of factors.
The factors that relate to how samples of mammary secretions are collected and analyzed
are summarized in the section on Methodology. Physiological state of the mammary
gland is a major determinant in the composition of mammary secretions, most clearly
seen in the differences between colostrum vs. milk composition. Sections on each of the
major components of mammary secretions are organized to address how composition
changes with stage of lactation, as well as how other factors affect composition. For
additional summary reviews of sow colostrum and milk composition, the reader is
referred to Neuhaus (1961), Bowland (1966), Hartmann and Holmes (1989), and Darragh
and Moughan (1998). Comparisons of sow milk composition with that of other species
can be found in reviews by Oftedal (1984), Oftedal and Iverson (1995), and Park (2011).
The tables in this chapter provide the reader with average concentrations of components
found in sow colostrum and milk, an indication of the range of reported values for the
components, and a listing of sources used to derive the average concentrations. The tables
are meant to provide representative values of the component concentrations based upon
a collection of studies that, in most cases, have provided estimates of components at
multiple points in lactation, or provided data that specifically focused on colostrum
composition. The tables are not meant to be an exhaustive compilation of all studies
that have evaluated composition. Table 9.1 includes the references from which reported
values were used in calculating the average component content for colostrum in Table 9.2
(parturition to 24 h postpartum) and for milk in Table 9.3 (48 h postpartum and beyond).
9.2
Methodology
9.2.1
Sampling of mammary secretions
All studies that report colostrum or milk composition rely on some method of collection of
the secretion. Collection of mammary secretions during parturition can be accomplished
without administration of oxytocin to stimulate milk ejection. Endogenous oxytocin
concentrations are elevated in a pulsatile manner during parturition (Gilbert
et al.
, 1994).
Oxytocin administration becomes necessary to collect milk samples by about 6 h after
birth of the first piglet (Jackson
et al.
, 1995). Administration of 10 to 80 IU oxytocin has
been used, with the quantity depending on route of administration, such as intravenous
(10 to 20 IU: Devillers
et al.
, 2004b; Theil
et al.
, 2004), intramuscular (20 to 40 IU; Jackson
