Milk fat globule size, phospholipid contents and composition of milk from purebred and Alpine-crossbred Mid-Eastern goats under confinement or grazing condition Nurit Argov-Argaman a, * , Oren Hadaya a , Tzach Glasser b , Hussein Muklada b , Levana Dvash c , Ronit Mesilati-Stahy a , Serge Yan Landau c a Department of Animal Science, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Israel b The Ramat Hanadiv Nature Park, Zikhron Yaakov, Israel c Department of Natural Resources, Institute of Plant Sciences, Agricultural Research Organization, the Volcani Center, P.O. Box 6, Bet Dagan, 50250 Israel article info Article history: Received 29 June 2015 Received in revised form 29 November 2015 Accepted 1 December 2015 Available online xxx abstract Milk fat globule (MFG) size and phospholipids (PL) content and composition were determined in milk collected at 65 (pretreatment), 110, 135 and 170 days of lactation from goats randomly assigned to grazing in Mediterranean brushland or fed clover hay indoors, in addition to concentrate. Daily feed intake and dietary contents of neutral detergent fibre and acid detergent fibre were higher in grazing goats, associated with milk richer in fat, with larger MFGs and 20% higher PL content. Smaller MFGs, produced by all confinement groups, was associated with 15 mgg 1 fat higher milk PL content. The greatest effect was found in the Damascus goats, with over 44% higher PL concentration, on milk fat basis, in the confined compared with grazing group. Our understanding of how PL content is modulated by the interaction between genetic background and nutrition will enable to achieve either PL-rich milk or PL-enriched milk fat. © 2016 Published by Elsevier Ltd. 1. Introduction Milk fat is secreted in a unique structure termed the milk fat globule (MFG) that consists of a triglyceride (TG) core covered with three layers of phospholipids (PLs), termed the MFG membrane. The MFG membrane consists of PLs, sphingolipids, glycolipids, cholesterol and proteins, all derived from the endoplasmic reticu- lum and apical membrane of the mammary epithelium (Mather & Keenan, 1998). The MFGs are secreted in a wide range of sizes, from the nanometre scale to over 15 mm in human milk (Michalski, Briard, Michel, Tasson, & Poulain, 2005) and in bovine milk (Mulder & Walstra, 1974), whereas a smaller MFG within the size range of 0.53e8.58 mm is found in caprine milk (Attaie & Richter, 1999). Understanding how MFG size is regulated is important for both industrial and health-related reasons. MFG size affects cheese ripening and structure, as well as stability of dairy products (Lopez et al., 2011; Michalski et al., 2003). Moreover, MFG size is tightly associated with its lipid composition, with a greater content of PL and sphingolipids in small versus large globules (Lopez et al., 2008; Mesilati-Stahy, Mida, & Argov-Argaman, 2011). A higher PL content in the human diet is desirable as PLs are considered to be health-promoting food ingredients (Kullenberg, Taylor, Schnieder, & Massing, 2012). For example, the plasma lipid profile was shown to be improved by the consumption of a PL-rich diet (Burgess et al., 2005). Furthermore, reduced occurrence of colon cancer was demonstrated when sphingomyelin (SM) was supplemented to a colon cancer-induced murine model (Dillehay, Webb, Schmelz, & Merrill, 1994). In another study, fortification of a milk replacement with MFG membrane decreased the number of days with fever and ear infections and improved cognitive perfor- mance of babies by the age of 1 (Lonnerdal, Timby, Domellof, Domelof, & Hernell, 2014; Timby, Domellif, Lonnerdal, & Domellof, 2014). Therefore, understanding how to increase the content of PL in milk would situate milk as a health-promoting food and modify the health implications of milk consumption dramatically. MFG size and consequently PL and sphingolipid content in milk were found to be associated with various hormonal, metabolic, and genetic factors. However, the mechanism controlling MFG size is still unclear. Insulin and energy balance (Argov-Argaman, Mbogori, * Corresponding author. Tel.: þ972 8 9489618. E-mail address: argov.nurit@mai.huji.ac.il (N. Argov-Argaman). Contents lists available at ScienceDirect International Dairy Journal journal homepage: www.elsevier.com/locate/idairyj http://dx.doi.org/10.1016/j.idairyj.2015.12.003 0958-6946/© 2016 Published by Elsevier Ltd. International Dairy Journal xxx (2016) 1e7 Please cite this article in press as: Argov-Argaman, N., et al., Milk fat globule size, phospholipid contents and composition of milk from purebred and Alpine-crossbred Mid-Eastern goats under confinement or grazing condition, International Dairy Journal (2016), http://dx.doi.org/10.1016/ j.idairyj.2015.12.003