Herd Mastitis & High Somatic Cell Count in Bovine Milk

HERD MASTITIS & HIGH SCC
MAIN CAUSES

1. Faults in the milking machine










2. Management faults






3. Trauma


4. Periparturient problems




5. Mineral deficiency
Comments

Liner slip, vacuum, pulsation ratios, stray electric voltages on the milk-line etc. Earthing faults on the milking machine may allow stray voltages to shock the teats/udder. This can cause a drop of 10-20% in herd milk yield and can be a cause of mastitis. The stray voltages can be intermittent (lasting milliseconds or seconds only) and can be very difficult to detect unless professional voltage recorders are left continuously on the milk line for 2-4 complete milkings.

Dirty/wet lying areas; inadequate teat dipping; poor milk line disinfection; failure to use individual tissue towels; removal of milk cluster without releasing the vacuum; failure to milk infected cows last; failure to use dry-cow antibiotics and seals etc

Trauma to udder and teats; rushing cows with pendulous udders

Herds with a high level of milk fever, dystocia, retained placenta fatty liver/Fat Cow syndrome etc also tend to have increased risk of mastitis, metritis, ketosis and lameness

Mineral deficiency is seldom a primary cause of mastitis. However, certain trace elements (Cu, Se, I, Zn, Co) and vitamins (E, A) are known to influence immune responses and their deficiency can be associated with a high incidence of clinical or subclinical infection.
REMEDIAL ACTIONS to reduce the risk and severity of mastitis include:
Remedial actions

1. Identify and correct causes

2. Mineral supplements?



















3. Bioplexed minerals?
Details

See 1-4, above. Cull high-SCC cows?

If the levels of Cu, Se, I, Zn, Co or P are low on blood test, it is advisable to increase the use of supplements high in those elements pre- and post-calving. A quick way to check if mineral deficiency is involved is to give a good mineral supplement high in P and trace-elements. If the animals do not show a good response within 3-6 weeks, the cause is unlikely to be due to mineral deficiency. Note: If minerals are only marginally deficient in blood, further supply of those minerals is unlikely to control mastitis.

Supplements of Vit E, Se and Zn reduced the incidence of subclinical mastitis in some deficient herds. High-P Lactation Minerals, supplying 240-1000 iu Vit E, 5-7 mg Se, 750 mg Zn/cow/d (in the daily allowance of dairy ration or Summer Nut) usually are recommended for 3-4 months post-calving.

Claims that organic trace-elements (such as Bioplexes) reduce somatic cell counts in milk need more proof. They are very expensive but many CoOps and compounders include 10-25% of the trace-element supplement as organic salts.
MILK DROP AND POOR MILK YIELD IN COWS
MAIN CAUSES

1. Infections

2. Mastitis

3. Parasites

4. Metabolic disorders

5. Antibiotic contamination of feed


6. Inadequate feed




7. Toxins

8. Stress










9. Low water intake


10. Miscellaneous disorders

11. Mineral deficiency
Comments

Leptospirosis, viruses etc

See Mastitis

Especially fluke and ostertagiasis

Hypomagnesaemia, ketosis, acidosis

Interference with ruminal microbial balance / digestion by lincomycin etc

Reduced intake or quality of grass or silage; unpalatable herbage (reduced intake on certain paddocks, sometimes associated with high quality but low fibre)

Plant, fungal, chemical, excess Mg intake

Stray electric voltages in the milk line, cold cow syndrome etc. Earthing faults on the milking machine may allow stray voltages to shock the teats/udder. This can cause a drop of 10-20% in herd milk yield and can be a cause of mastitis. The stray voltages can be intermittent (lasting milliseconds or seconds only) and can be very difficult to detect unless professional voltage recorders are left continuously on the milk line for 2-4 complete milkings.

Dirty water, saline- or heavily mineralised- water; water restriction

Lameness, pain, scour, respiratory disorder etc

Apart from hypomagnesaemia, mineral deficiency seldom causes poor milk yield in Ireland. Occasionally deficiency of P, Na, Cu, Se, I or Co may be involved.
REMEDIAL ACTIONS to reduce the risk and severity of milk drop include:
Remedial actions

1. Identify and correct the causes





2. Check the water supply




























3. Mineral supplements?
Details

Check for, and correct, infection, mastitis, parasitism, metabolic disorders, antibiotic contamination of feed, inadequate feed, toxins, stress, poor water supply and miscellaneous disorders.

A formula to estimate total water requirements for cows is: water intake (kg/d) = 1.58 X (feed DMI, kg/d) + 0.9 X (milk yield, kg/d) + 0.05 X (Na intake, g/d) + 1.2 X (mean minimum air temperature, oC) + 16.

Example: The estimate of total water requirement for a Friesian cow, eating 67 kg grass with 21% DM (i.e. 14.1 kg grass DM/cow/d), yielding 28 kg milk/cow/d, with Na intake of 40 g/cow/d, minimum air temperature 10oC, is: (1.58 * 67 * 0.21) + (0.9 * 28) + (0.05 * 40) + (1.2 * 10) + 16 = 67 kg/cow/d. To estimate the requirement for water drunk, subtract water in the feed from the estimate. In this example, the grass (21% DM, thus 79% water) supplies (67 * 0.79) = 53 kg water/cow/d, leaving a requirement for (67 - 53) = 14 kg drinking water/cow/d.

However, that formula may underestimate the water drunk by cows at pasture. Over weeks or months on Irish pasture, milking cows drink about 40 kg trough water/cow/d (from 7 kg on cold wet days to 70 kg on hot sunny days). If cows milk poorly, check the supply and quality of drinking water. Flow-meters can be fitted to each trough to measure mean daily water intake by cows.

If the levels of Mg, P, Cu, Se, I or Co are low or very low on blood test, it is advisable to increase the input of those elements. Note that if minerals are only marginally deficient in blood, further supplementation with those minerals is unlikely to improve milk yield.

A quick way to check if mineral deficiency is involved is to give a high-P lactation mineral supplement high in trace elements. This can be given in a special Summer Nut, fed at 1-2 kg/cow/d at grass. The daily allowance of nut should supply 30-50 g Mg, 350-450 mg Cu, 3-5 mg Se, 60 mg I/cow/d.

If the milk yield does not improve within 3-6 weeks, the cause is unlikely to be mineral deficiency.
Phil Rogers MRCVS, Lucan, Dublin, Ireland​
THE NYCAVMA IS HONORED TO HOST & MANAGE THE PHIL ROGERS ARCHIVE