ADSC 2010: Dairy Production

Future of dairy cash receipts

Increasing

Trends for number of dairy cows and products

Number of dairy cows is decreasing, but products are increasing (more efficient)

Trend of size of dairy farms

small farms are decreasing, large farms are increasing

Top dairy state

California is top, wisconsin is close second

Demographic data of dairy producers

Younger than beef producers, heavily male, pretty old, spent more years farming than beef, primary occupation is farming

Dairy production differences

lots more net positive income, hire more labor, higher feed costs

Holstein

White with black or red blobs, large milk volume

Jersey

Tan color, darker face, smallest, friendly, produces milk high in butter fat

Brown Swiss

Darker brown/gray brown, larger than Jerseys, friendly, high protein in milk

Guernsey

White with golden spots, fluffy tail, beta carotin in milk (vitmain A)

Ayrshire

Similar coloring to Guernsey, tolerant of different environments, vigor, good all around cow

Milking Shorthorn

dual purpose, brick red and white (spotted)

Mammary gland

• synthesis, storage, and secretion of milk

• four functional glands (quarters) with no interchange of milk

• rear quarters produce ~60%, fore quarters produce ~40%

Udder support

• Median suspensory ligament- middle, seperates udder into left and right

• Lateral suspensory ligament- on the side

• Connective tissue

Alveoli (basic secretory unit)

• millions of hollow, grape-like structures that produce and secrete milk

• Epithelial cells- milk-producing cells

• myoepithelial cells- smooth muscle cells that contract and cause milk secretion into the lumen of the alveolus

• As the lumen fills with milk and expands, milk is forced into the duct system of the mammary gland

Lobules

groups of alevoli surrounded by thin fibrous membranes

Lobes

Groups of lobules that drain into a single duct system

Milk ducts

ducts that drain the lobes (~30 per lobe)

Gland cistern (one/quarter)

• pocket formed at the beginings of milk ducts

• short term storage site

Teat cistern

cavity within the teat

Streak canal

opening of the teat to the environment

Teat sphincter

smooth muscle closure around streak canal

Mammary development

• begins in puberty

• estrogen involved in duct developmet

  • porgesterone needed for alveolar-lobule development

Prolaction

stimulates and maintains milk secretion

Oxytocin

• responsible for milk let-down

• Adrenaline blocks the effect of oxytocin

Thyroxin, growht hormone, adrenal steroids

involved in the maintenance of milk secretion

Milk letdown

sensory stimulus produces a nerve impulse to the brain, which causes oxytocin release

Milk Production Cycle

1. Parturition (day 0)

2. Colostrum production (day 0-3)

• first milk produced post-partum, high in immunoglobins

• calf has ability to absorb for 24 hrs

• by 3-5 days post partum, milk is acceptable for human consumption

3. Milk Production

• after partuition, milk yield increases rapdily to a peak (~45-90 days)

• persistency - degree of maintenance of lactation (this month’s production / last months) 85-90%

• Peak production in holstein is ~70-80 lb/d