319 Chantal Farmer (ed.) Te gestating and lactating sow DOI 10.3920/978-90-8686-803-2_14, © Wageningen Academic Publishers 2015 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. Te amount of nutrients available to mammary tissue is dependent upon the concentrations of nutrients in blood and the rate of its fow to the lactating glands. Nutrient availability to the udder may be estimated by measuring mammary arteriovenous diferences, and mammary blood fow 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 fow to the udder is infuenced by numerous factors, such as litter size, time since feeding, postural behaviour, vasoactive substances, and ambient temperature; yet, the single most important efector of mammary blood fow 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. Te uptake of amino acids by sow mammary glands has been extensively studied and is afected 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 afected 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 specifc 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; Teil, 2015 from this book). It is therefore imperative to fnd ways to https://www.wageningenacademic.com/doi/pdf/10.3920/978-90-8686-803-2_14 - Thursday, November 04, 2021 3:19:10 PM - IP Address:3.235.191.121