Great Lakes Dairy Sheep Symposium - the Department of Animal ...

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Stelwagen, K., Davis S.R., Farr V.C., Prosser C.G., and Sherlock R.A. 1994. Mammary epithelial cell tight junction integrity and mammary blood flow during an extended milking interval in goats. J. Dairy Sci., 77:426-432. Swalve H.H. 2000. Theoretical basis and computational methods for different test day genetic evaluation methods. J. Dairy Sci., 83:1115-1124. Swalve, H. H. 1995. Genetic relationship between dairy lactation persistency and yield. J. Anim. Breed. Genet., 112:303-311. Thomas D. L., Berger Y. M. , and McKusick B. C. 2001. Effects of breed, management system, and nutrition on milk yield and milk composition of dairy sheep. J. Anim. Sci., 79(suppl. E):E16-E20. Togashi, K., and C. Y. Lin. 2003. Modifying the lactation curve to improve lactation milk and persistency. J. Dairy Sci. 86:1487-1493. Tonner E., Allan G.J., and Flint D.J. 2000. Hormonal control of plasmin and tissue-type plasminogen activator activity in rat milk during involution of the mammary gland. J. Endocrinol., 167:265-273. Wilde C.J., and Knight C.H. 1990. Milk yield and mammary function in goats during and after once-daily milking. J. Dairy Res., 57:441-447. Wilde C.J., Henderson A.J., Knight C.H., Blatchford D.R., Faulkner A., and Vernon R.G. 1987. Effects of long-term thrice-daily milking on mammary enzyme activity, cell population and milk yield in the goat. J. Anim. Sci., 64:533-539. Wohlt J.E., Foy Jr V.L., Kniffen D.M., Trout J.R. 1984. Milk yield by Dorset ewes as affected by sibling status, sex and age of lamb, and measurement. J.Dairy Sci., 67:802-807. Wood P.D.P. 1967. Algebraic model of the lactation curve in cattle. Nature, 216:164–165. Zamiri M. J., Qotbi A., and Izadifard J. 2001. Effect of daily oxytocin injection on milk yield and lactation length in sheep. Small Rum. Res., 40:179-185. 68
Introduction MILK FAT SYNTHESIS AND ITS REGULATION IN DAIRY SHEEP Adam L. Lock,* Liam A. Sinclair, † and Dale E. Bauman* *Cornell University, New York, USA † Harper Adams University College, Shropshire, UK Milk and dairy products were recognized as important foods as early as 4000 B.C. as evidenced by rock drawings from the Sahara. Today, the important contribution of milk and dairy products in meeting our dietary requirements for energy, high quality protein and several key minerals and vitamins are well documented. With the projected growth in world population and the increased demand for animal-derived food products as living standards improve, dairy products will undoubtedly continue to be an important dietary source of nutrients (Bauman et al., 2005a). Fat is an important component of milk for a number of reasons. Nutritionally, fat is the major energy component of milk and it accounts for many of the physical properties, manufacturing characteristics, and sensory attributes of milk and dairy products. The fat content of milk is highly variable and the environmental and physiological factors affecting milk fat have been extensively characterized. Furthermore, nutritional quality has become increasingly important in food choices because of consumer awareness of the link between diet and health; importantly, milk fat has been shown to contain a number of bioactive components that may provide benefits to human health which has led to an interest in “designing” milk fat to improve its healthfulness and functional properties. Nutrition is the predominant factor affecting milk fat and it represents a practical tool to alter the yield and fatty acid composition of milk fat. The impact of nutrition on fat content and fatty acid composition of milk in the bovine has been extensively reviewed (Palmquist et al., 1993; Lock and Shingfield, 2004; Lock and Bauman, 2004). Therefore, the purpose of this review is to provide an overview of the biology of milk fat synthesis in ruminants, discuss an innovative method for altering the fat content of sheep milk and its possible application, and consider the manipulation of the fatty acid composition of sheep milk fat. Milk Fat Synthesis Fat is the most variable component in the milk of ruminants. The concentration of fat in milk is influenced by animal and environmental factors such as breed, diet, stage of lactation, season of year, ambient temperature, and body condition (Figure 1). Milk fat consists of droplets of triglycerides that are coated with cell membrane (milk fat globular membrane; MFGM). Thus, the majority of the fat content of milk is triglycerides (~95%) with phospholipids, cholesterol, diacylglycerols, monoacylglycerols, and free fatty acids constituting the remainder (Lock and Shingfield, 2004). Ruminants are estimated to have over 400 different fatty acids comprising milk fat triglycerides, but the majority of the fatty acids have chain lengths between four and eighteen carbons. In ruminants, fatty acids in milk fat arise from two sources that contribute equally (molar basis), de novo synthesis within the mammary gland and uptake of preformed fatty acids from circulation (McGuire and Bauman, 2002). An overview of the metabolic pathways and some of the key enzymes involved in milk fat synthesis are shown in Figure 2. 69
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Proceedings of the 11 th Annual GRE
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Table of Contents Program of Events
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Program of Events Thursday, Novembe
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Speakers at the symposium site in B
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Gold: Sponsors Babcock Institute fo
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“YOU WANT TO MILK WHAT?” IMPORT
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already have their milking faciliti
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efficient or just selling milk (or
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production doubles. However, there
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Total production (pounds) Percentag
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Milk production (pounds) Average mi
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Percentage of ewes in each system 1
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5. Ice Cream and Butter: • raw mi
Page 27 and 28: 3. Fresh Cheeses made from pasteuri
Page 29 and 30: The Vermont Cheese Council (www.vtc
Page 31 and 32: 1 x Brine Tank (10’ long x 3 ft.
Page 33 and 34: LAMB REARING STRATEGIES: FARMER PAN
Page 35 and 36: BONNIEVIEW FARM’S LAMB REARING ST
Page 37 and 38: REARING LAMBS AT 3-CORNER FIELD FAR
Page 39 and 40: PROFITABILITY OF SMALL RUMINANT FAR
Page 41 and 42: Table I. General Farm Description L
Page 43 and 44: Table 4. Business Balance Sheet Ass
Page 45 and 46: Table 5. Income Statement Income Av
Page 47 and 48: Lifestyle is a definite reason for
Page 49 and 50: Grossman et al., 1999). Animals wit
Page 51 and 52: Physiological Factors Affecting Lac
Page 53 and 54: Recently, it has been hypothesized
Page 55 and 56: (co)variate in the genetic model us
Page 57 and 58: show that milk production increases
Page 59 and 60: Figure 6 - Lactation curves of ewes
Page 61 and 62: milk yield (g/d) 3000 2500 2000 150
Page 63 and 64: a genetic potential to produce more
Page 65 and 66: when compared with the control grou
Page 67 and 68: probability (%) 70 60 50 40 30 20 1
Page 69 and 70: considered “healthy” if every S
Page 71 and 72: Finally, udder health has to be con
Page 73 and 74: De Maria Ghionna C., Dell’Aquila.
Page 75 and 76: Manalu, W., Sumaryadi, M.Y., Sudjat
Page 77: Rupp R., Boichard D., Barbat A., As
Page 81 and 82: The variety of fatty acids allows t
Page 83 and 84: Germany); we have shown previously
Page 85 and 86: Manipulating Milk Fatty Acid Compos
Page 87 and 88: increase in rumen output of vacceni
Page 89 and 90: Luna et al., 2005; Nudda et al., 20
Page 91 and 92: Cabiddu, A., M. Decandia, M. Addis,
Page 93 and 94: MANAGING YOUR OWN RETAIL SHOP: MARK
Page 95 and 96: The Reality our feta demonstrates t
Page 97 and 98: Meat and meat dishes: 1. Legs: whol
Page 99 and 100: 5. We have daily visits from chefs
Page 101 and 102: HOW TO GRAZE DAIRY SHEEP AND SUPPLE
Page 103 and 104: significantly increase milk product
Page 105 and 106: All parameters are significantly di
Page 107 and 108: Table 6 - Dry matter intake and mil
Page 109 and 110: animals can reduce intake, as they
Page 111 and 112: Milk fat and protein concentrations
Page 113 and 114: fat concentration can be used as a
Page 115 and 116: (1998), working with adult Sarda ew
Page 117 and 118: equirements. The relationship found
Page 119 and 120: that there have not been enough stu
Page 121 and 122: Grazing methods Grazing methods are
Page 123 and 124: How should the number of paddocks b
Page 125 and 126: Table 16 - Description of four past
Page 127 and 128: a) concentrates supplied during mil
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References Arnold G.W., and Dudzins
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supplemented with corn grain. Optio
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succeeding add on pastures smaller
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diverse forage have much to do with
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dairy farming. In fact, Vermont agr
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thermized (holding at a temperature
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speaking, the risks associated with
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FARMER PANEL ON LABOR HOW TO ATTRAC
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• Animal Health Products • Spec
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Cultivating Healthy Communities UVM
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139
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Hudson Valley Camemberts Pure Sheep
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Premier Dairy Service, LLC Argyle,
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www.vermontagriculture.com 145
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