ADSC 2010 Lecture 30 Outline of Last Lecture I Artificial Insemination A Time for Breeding a Cow b Ewe c Sow d Mare II Embryo Transfer A Benefits B Limitations C Process III Pregnancy Detection A Cow B Ewe C Sow D Mare Outline of Current Lecture I The Dairy Industry II Feedstuffs Utilized A Roughages 1 Pasture 2 Hay B Concentrates III Milk Dairy Production A Mammary Gland a Function b Udder Support c Udder Structures 1 Alveoli 2 Lobules 3 Lobes 4 Milk Ducts IV V 5 Gland Cistern 6 Teat Cistern 7 Streak Canal 8 Teat Sphincter Milk Production Regulation A Mammary Development B Hormonal control of Lactation C Milk Letdown a Oxytocin b Milking Rate c Adrenaline Milk Production Cycle A Parturition B Colostrum Production Current Lecture I The Dairy Industry High Efficiency of Nutrient Utilization Energy 17 25 Protein 28 36 High Investment Cost Animal Unit Cow cost Feed cost Facilities Milking Parlor Waste Environment Management High Income Animal Unit GA o 16 500 cow year x 20 3 630 cow year UGA o 20 550 cow year x 20 4 521 cow year Chart Profit in the Dairy Industry by Operation Size 2011 II Feedstuffs Utilized A Roughages about 4 5 tons cow year 1 Pasture silage corn sorghum grass 2 Hay cottonseed hulls B Concentrates 1 Corn III 2 Soy hulls 3 Soybean meal 4 Whole cottonseed 5 By Products o Brewers grain o Corn gluten feed o Animal protein o Citrus beet pulp o Salad waste Milk Dairy Production Production cow increasing Total pounds of milk 1950 1970 flat 1970 now increasing A Mammary Gland a Function synthesize store secrete milk Cow has four functional glands quarters with no interchange of milk Rear quarters produce about 60 Fore quarters produce about 40 b Udder Support 1 Median suspensory ligament 2 Lateral suspensory ligament 3 Connective tissue Inner mammary grove between udders c Udder Structures 1 Alveoli basic secretory unit o Millions of hollow grape like structures that produce and secrete milk o Epithelial cells milk producing cells o Myoepithelial Cells smooth muscle cells that contract and cause milk secretion into the lumen of the alveolus o As the lumen fills with milk and expands milk is forced into the duct system of the mammary gland 2 Lobules groups of alveoli surrounded by a thin fibrous membrane 3 Lobes groups of lobules that drain into a single duct system 4 Milk Ducts ducts that drain lobes about 30 duct 5 Gland Cistern one quarter IV V o Pocket formed at the openings of the milk ducts o Short term storage site 6 Teat Cistern cavity within teat 7 Streak Canal opening of teat to environment 8 Teat Sphincter smooth muscle closure around streak canal Milk Production Regulation A Mammary Development o Begins at puberty o Estrogen involved in duct development o Progesterone needed for alveolar lobule development B Hormonal control of Lactation o Prolactin stimulates maintains milk secretion o Thyroxin GH and Adrenal Steroids are involved in maintenance of milk secretion C Milk Letdown o Sensory stimulus tactile sight sound smell produces nerve impulse to brain which causes oxytocin to release a Oxytocin o Reaches udder 45 60 seconds following stimulation o Contraction of Myoepithelial cells o Pushes milk out down into milk ducts o Effect maintained about eight minutes b Milking Rate average cow about 5 minutes c Adrenaline blocks oxytocin effects o Any factor prolonging milking reduces oxytocin effects and results in incomplete milk out o Incomplete milk out results in rapid decline in milk production Milk Production Cycle A Parturition Day 0 o Cow lactates in response to calving B Colostrum Production Day 0 3 o First milk post partum o High in immunoglobulin proteins that provide disease resistance o Calf can absorb that protein about 24 hours o Calf removed after receiving colostrum o Calf survival rate 50 70 lower without colostrum o By 3 5 days post partum milk is acceptable for human consumption
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