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MANIPULATING MILK YIELD AND COMPOSITION. Leo Timms Iowa State University. POUNDS VS. PERCENTAGES. GENETICS. Milk composition/ yield highly heritable Heritability (h 2 ) milk yield .27 % fat .58 % protein .49 % lactose .55 Correlation between % fat and protein: ~.5
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MANIPULATING MILK YIELD AND COMPOSITION Leo Timms Iowa State University
POUNDS VS. PERCENTAGES
GENETICS • Milk composition/ yield highly heritable • Heritability (h2) • milk yield .27 • % fat .58 • % protein .49 • % lactose .55 • Correlation between % fat and protein: ~.5 • Correlation between yield and % fat : ~ -.2 • Correlation between yield and % protein: -.1 • Correlation between yield and lbs. fat / prot. ++
GENETICS • Milk composition/ yield highly heritable • Species and/ or Breed differences • Fat / protein % • Milk fat globule size • Beta carotene • Fatty acid profiles • Casein genotypes
PHYSIOLOGICAL FACTORS • Age • Stage of lactation • colostrum - rest of lactation • Dry period ( non-lactating) • Milking fraction (fat, SCC, IG?) • Milking interval • Reproduction: estrus/ follicular cyst/pregnancy • Temperature • Factors that affect/ compete for nutrients
PHYSIOLOGICAL FACTORS • METABOLIC DISEASES • Ketosis (glucose shortage – fat mobilized) • may increase or decrease yield • increased fat test ( lipolysis) • increased milk ketones • Milk Fever (Ca drain) • decreased production • MASTITIS ( Future talk)
NUTRITIONAL FACTORS IF YOU DON’T FEED THEM, THEY WONT MILK! (DMI)
NUTRITIONAL FACTORS • Underfeed energy (CHO) Volume, lactose, protein • Underfeed protein Volume, lactose protein Underfeeding energy: greatest effects!
LACTOSE (VOLUME) • GLUCOSE demands! • Traditionally hard to change! • Propylene glycol/ glycerol drenches (bolus effect important!) • Rumensin • Chromium • Cobalt and Vitamin B12 • Niacin and choline (rumen protected)
MILK PROTEINS • Not as easy to change as one thinks! • Worth lots of $ so want to increase! • Dietary protein: minimal effects • Protected proteins/AA: minimal when protein is sufficient • Oilseeds: protein% • Hyperinsulinaemic/ euglycaemic clamp • Increased milk protein 25% • Same plasma AA: blood flow/AA extraction
VITAMINS • Vitamin A: fresh vs stored feeds • Increase feed Vit A/E: milk • May be more important for mastitis and somatic cells
MINERALS • Very hard to change!!! IODINE!
MILK LIPIDS • Easiest to change: diet labile • Change amount and types of FA • Saturated/protected oils: temp • Excessive grain / limited fiber • Rumen buffers: if low, will • Excess or free oilseeds: • Fiber digestion , CLA isomer • Feed CLA: CLA ; Fat