Agriculture Reference
In-Depth Information
14. Mammary blood flow and nutrient uptake
C. Farmer
1*
, N.L. Trottier
2
and J.Y. Dourmad
3
1
Agriculture and Agri-Food Canada, Dairy and Swine R & D Centre, 2000 College St.,
Sherbrooke, QC, J1M 0C8, Canada;
chantal.farmer@agr.gc.ca
2
Michigan State University, Department of Animal Science, 2209 Anthony Hall, East
Lansing, MI 48824, USA
3
INRA-Agrocampus Ouest, UMR1348 PEGASE, 35590 Saint-Gilles, France
Abstract
Sow milk is the major source of nutrients for suckling piglets and taking into account the
large litter sizes of our current sow genotypes, it is imperative to maximize nutrient use by
the mammary gland. The amount of nutrients available to mammary tissue is dependent
upon the concentrations of nutrients in blood and the rate of its flow to the lactating
glands. Nutrient availability to the udder may be estimated by measuring mammary
arteriovenous differences, and mammary blood flow can be measured either directly or
via indirect calculations. For all these measures, mammary venous and arterial blood
samplings are required and catheters must be inserted in mammary veins. Blood flow
to the udder is influenced by numerous factors, such as litter size, time since feeding,
postural behaviour, vasoactive substances, and ambient temperature; yet, the single most
important effector of mammary blood flow is milk removal. Glucose represents 40 to
60% of the total carbon mass taken up by sow mammary tissue and its uptake by the
mammary gland appears to be mediated by glucose transporter proteins. Other energetic
precursors which are used by the mammary gland are triglycerides, phospholipids,
acetate, propionate and lactate. The uptake of amino acids by sow mammary glands has
been extensively studied and is affected by diet, stage of lactation, and milk demand.
Recent data also showed that amino acid uptake is controlled by transporter proteins that
channel amino acids intracellularly, and that these proteins are in turn affected by diet
and physiological status. Data on mammary uptake of hormones are contradictory; yet,
the endocrine involvement in the regulation of milk synthetic processes is evidenced by
the presence of specific hormonal receptors in mammary tissue.
Keywords:
dietary nutrients, lactation, mammary gland, mammary uptake, sow
14.1
Introduction
Sow milk yield is the major determinant of growth of suckling piglets and, in turn, weight
of piglets at weaning has a major impact on their post-weaning gain (Klindt, 2003).
Yet, primiparous sows cannot produce optimal milk yields because of underdeveloped
mammary tissue, low voluntary feed intake during lactation, and their prolonged catabolic
state present during late-gestation and lactation (see Chapter 4; Farmer and Hurley, 2015
and Chapter 7; heil, 2015 from this topic). It is therefore imperative to ind ways to
