MANIPULATING MILK YIELD AND COMPOSITION

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MANIPULATING MILK YIELD AND COMPOSITION

• Leo Timms
• Iowa State University

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POUNDS VS. PERCENTAGES
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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

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GENETICS

• Milk composition/ yield highly heritable
• Breed differences
• Fat / protein
• Milk fat globule size
• Beta carotene
• Fatty acid profiles
• Casein genotypes

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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

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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)

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NUTRITIONAL FACTORS

• IF YOU DONT FEED THEM, THEY WONT MILK! (DMI)

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NUTRITIONAL FACTORS

• Underfeed energy (CHO)
• Volume, lactose, protein
• Underfeed protein
• Volume, lactose protein
• Underfeeding energy greatest effects!

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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)

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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

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VITAMINS

• Vitamin A fresh vs stored feeds
• Increase feed Vit A/E milk
• May be more important for mastitis and somatic
  cells

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MINERALS

• Very hard to change!!!
• IODINE!
• SELENIUM!

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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