Composition of milk
- Lactose- 4.9%
- -Ca, P, K
- Water- 87.5%
- Protein and Mineral/Ash are critical in terms of biological value.
- Calcium is hard to find in absorbable forms
Properties/Elements of milk
specific gravity, heat, freezing point, pigments, vitamins, enzymes, gases
- Gravity: 1.032@60 degrees F
- Heat: 938
- Freezing point: -0.535 degrees C
- -Lactoflauin-blueish yellow
- Vitamins: A, B complex, C, D, E, K
- Enzymes: Amylase, Lipases, Galactose
- Gases: CO2, Nitrogen, O2
What is the principle milk carbohydrate?
Lactose, a disaccharide composed of glucose and galactose
The weight of residue after incineration ("ash") represents the mineral fraction.
Milk composition in different stages of lactation
- Total solids: C=23.9 M=12.9
- Protein: C=14.0 M=3.1
- antibodies in the colostrum
- are composed of protein material and are critical for the health of the new calf, conferring some degree of passive immunity against a variety of early diseases
- First lactation cows display a slightly different shape to their lactation curve, with a lower peak milk production and more successful maintenance of milk production levels later in the lactation.
- 2 year old does not peak as high because not as many secretory cells and still growing
Normal Daily variation likely factors
- Thermal sites
- environmental, hormonal stress
- milking practices
- (Not Major)Body condition: affects for test (usually negatively, only if cow is severely under-conditon)
- compares milk production from cattle at different stages of development.
- Takes into account her age (# of lasts) and represents her current production as a function of what she could be expected to produce when fully mature
- 2 yr old= 75% ME
- 3 yr old= 85% ME
- 4 yr old= 92% ME
- 5 yr old= 98% ME
Stage of gestation affects on milk production levels
- drop in milk yield late in pregnancy
- decrease is due to hormonal effects rather that to increased nutrient requirements posed by the unborn calf.
Photoperiod affects on milk production levels
Increased daylight hours:increased feed intake=increased milk, assuming temp. effects could be controlled.
Nutrition affects on milk production levels
- Cattle on higher nutritional plane fully express potential for protein production
- must contain AT LEAST 40% of dry matter coming from roughages.
- R:C may be higher than 40%, in practice it doesn't often get above 60% due to the higher nutrient density.
- feeding sun-cured roughages increases direct exposure to sunlight will increase Vitamin D in milk.
- Vitamin A content in milk can be increased by providing more of its precursor, B-carotene, in the diet
How rBST is made
bovine DNA containing the code for growth hormone (a peptide hormone) is isolated, copied and inserted into the genetic material of E. Coli bacteria. The bacteria combines the bovine DNA into its own circular strand (called plasmid) and functions as a protein manufacturing plant.
Taret organ for bST
- the liver
- When binds to liver it triggers IGF-1 (insulin-like growth factor)
- BST causes increase in feed intake=increase nutrient increase
- Somatropin is produced by all farm animals and humans. Each species produces one or more unique somatropins
- BST is a peptide (protein) hormone that contains 191 amino acids, each is normally produced or consumed by man
- rBST may be produced using recombinant DNA technology that is IDENTICAL to at least one of the naturally occurring forms.
- Administration of rBST to lactating dairy cows in appropriate circumstances will effect increased milk production through increased dry matter intake
- BST from cows will not cause any response to humans
Appropriate considerations for BST success
- 1. Stage of lactation
- -should be past peak in daily production, in 9th or 10th week of lactation
- 2. Body condition
- -thin cows manufacture fewer receptors for BST
- -reduced receptors in liver=reduced response
- 3. Reproductive history
- -more likely a reason for delay rather than use/not use
- -fertility/milk production relationship continues, whether BST is in the picture of not
- inflammation of the mammary gland
- not infection
Signs of clinical mastitis
- redness, heat, pain (tenderness) and/or swelling
- can develop into clinical
- occurs with much greater frequency (15-40 times higher) than clinical mastitis
Clinical mastitis detection
- symptoms of a progressive case of clinical mastitis tend to move from involvement of only the milk to the udder to (possibly) the entire cow.
- -milk flakes, clots, watery, bloody
- -udder-heat, redness, swelling, pain
- -cow-general depression, increased temp. reduced feed intake
What are somatic Cells
- somatic (body) cells-three main types/tow are defensive
- a collection of body cells present in the mammary secretion cells are living and dead, and arise from several sources:
- -surrounding tissues
- -blood circulation
- -alveolar tissue
- higher SCC=greater probability of mastitis
- SCC is an indirect measure of health status of the udder
- Major contributes to SCC
- -polymorphonuclear neutrophils (PMN)
- -milk secretory cells (involution, severe infection)
- "white blood cells"
- present to provide some aspect of defense against foreign pathogens
types of white blood cells that attempt to protect the body by engulfing and digesting "non-self" materials. The process is called phagocytosis
The process of specific antibodies coating the surface of a foreign organism or antigen. Opsonization increases efficiency of phagocytoses
- major component in uninfected mammary gland
- concentrated in tissues surrounding openings to the outside
- sending out chemical signals to summon assistance from other leukocytes
- Function "gatekeeper" or "sentinel"
- Two Jobs:
- phagocytosis of foreign pathogens
- secretion of chemotactic agents to summon PMN
Common chemotactic agents
- cause massive number of other types of leukocytes to enter the mammary gland and attempt to kill the foreign organism.
- Complement fragments
- Hydrogen peroxide
Polymorphonuclear Neutrophils (PMN)
- respond to chemotactic signals and flood into the mammary gland rapidly.
- PMN are phagocytes and attempt to kill by ingestion
Milk Secretory Cells
- minimal contribution to SCC except in specific situation:
- -INVOLUTION: dry off, switch active cells to dormant
- severe infection with toxic damage to cells
Other important leukocytes
- Are important in the immune response primarily because they produce antibodies or immunoglobulins
- activated (irritated) B-lymphocytes, called plasma cells, produce specific antibodies against disease
- antibodies enhance ability of phagocytes to ingest and kill
- enable the phagocytes to most effectively engulf and kill
the variable portion of the antibodies binds to the microorganism in a process called opsonization.
What are vaccination strategies focused on?
stimulation of B-lymphocytes with the goal of creating large numbers of antibodies specific against the disease on interest.
the activated B-cell, called a plasma cell, is the cell that produces the vital products
- secrete biologically active proteins called lymphokines
- secrete materials that direct movement and activity level of other leukocytes
Streptococcus Agalactiae "Strep Ag"
- only major pathogen that can be permanently eliminated from the herd-excellent cure rate.
- Lives in the udder of the cow
- can be transferred by factors associated with milking
Staphylococcus Aureus "staph aureus"
- lives in/on udder
- least curable/resistant to antibodies
- well controlled with strict hygiene
- highly invasive and wall itself off
- live in/on the cow and are generally present in areas such as bedding, soil, water, and manure
- controlled by teat dipping and dry cow therapy
- cure rate: 60-30%
Coliforms (E.coli, Klebsiella, Enterobacter)
- typically causes sudden acute mastitis-can be fatal
- determined with gram negative test
- antibiotic therapy is ineffective instead use anti-inflammatory treatment
- most infections occur between millings when teat dip effectiveness is decreased
Occasional and Special Problem organisms
- C. pyogens
- Nocardia, Prototheca
- smallest free-living organisms and lack cell wall
- highly contagious
- -significant purulent discharge (pus)
- -frequent involvement of more than one quarter
- -tannish milk with flakes and sediment
- bluish tent to milk
- grape-like odor
- infections may be caused by poor milking parlor sanitation, inoculation through use of contaminated multi-use antibiotic preparations, excessive exposure to contaminated water.
- establish of subclinical infections is a basic problem in mastitis because:
- -15-40 times more prevalent than clinical
- -60-75% of total dollar loss due to masts
- -unseen, difficult to detect, long durations of infection
Efforts to control subclinical mastitis should focus on:
- Dry cow therapy
- Lactation therapy of appropriate clinical
How are contagious infections spread vs. Environmental
- Contagious: cow to cow, milkers poor techniques or flaw in machinery
- Environmental: environment to cow, non-miking environment. Found in soil, manure, bedding, and water.
5 Point plan for mastitis Prevention
- 1. Use functionally adequate milking machines and systems in the correct manner.
- 2. Dip teats after milking with an effective product.
- 3. (If you choose to treat) Administer promptly a full series of recommended treatments to clinical cases.
- 4. Treat all quarters of all cows at drying off.
- 5. Cull animals with chronic infections that do not respond to treatment
the "flushing" action of milking stops, udder sanitizing and teat dipping cease, and the streak canal becomes dilated and shortened due to milk buildup.
Waxy substance that forms a plug in the streak canal, effectively sealing off the opening of the mammary gland to the outside world.
- once through the involution period, the gland secretes several types of anti-bacterial factors, including antibodies and lactoferrin.
- Binds to iron molecules, which coliform organisms have a high need for.
interferes with the ability of lactoferrin to bind with iron, so its importance as a protective factor during lactation is reduced.
On an GIVEN DAY-% of cows that are clinical or are being treated
- more than 2%=needs work
During ANY MONTH-% of cows having a clinical case
- less than 5%=good
- over 10%=serious, needs attention
PER LACTATION-average number of clinical cases per cow per lactation
- less than .75 cases/cow/lactation=good
- greater than 1.25=needs improvement
Direct vs Indirect Mastitis
- Indirect: measuring the reaction of the cow, sec test
- Direct: culture of the milk
CMT Score and SCC count
- Negative=200,000 scc
- Trace (suspicious)=150-500,000 scc
- 1 (suspicious)=400-1,500,000 scc
- 2 (positive) = 800-5,000,000 scc
- 3 (positive) = >5,000,000 scc
- 25-40% of total
- antibiotic treatment
- veterinary services
- discarded milk
- early culling
- time (treatment, management)
- 60-75% of total
- decreased milk production
- decreased milk quality
- early culling
- Good hygiene, dipping, dry treatment = $100/cow/year
- Poor hygiene, dipping, dry treatment = $225/cow/year
3 step approach to troubleshooting mastitis
- STEP 1: Identify Infected Cows
- -routine monitoring at specific times in the lactation cycle
- -culturing of clinical cases and/or high somatic cell cows
- STEP 2: Determine major organism(s) causing infection
- -lab testing vs. on-farm analysis
- -specialized culturing process for some pathogens
- STEP 3: Analyze Management situations
- -Contagious or environment problem
- -Where to focus attention
- These antimicrobials interfere with bacterial cell wall growth
- most effective when given in the microorganism's active growth phase
- comprise the majority of the β-lactams
- only one used in lactating cows: Cephapirin
- not as effective against anaerobes as Penicillins have been
Interfering with microbial protein synthesis and tend to be active and effective in higher pH conditions
- considered narrow spectrum and inhibits bacterial growth through both mechanisms mentioned above.
- commonly used in combination with others such as penicillin
- develop resistance against it fairly rapidly