Herd Mastitis & High Somatic Cell Count in Bovine Milk

Herd Mastitis, high SCC & Milk Drop in Cows

Phil Rogers MRCVS <philrogers@eircom.net>
Grange Research Centre, Dunsany, Co. Meath, Ireland
21-Mar-2001

Herd Mastitis, high SCC (Causes | Remedies) | Herd Milk Drop (Causes & Remedies)

HERD MASTITIS & HIGH SCC

MAIN CAUSES Comments

1 Faults in the milking machine 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.

2 Management faults 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

3 Trauma Trauma to udder and teats; rushing cows with pendulous udders

4 Periparturient problems 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

5 Mineral deficiency 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 Details

1 Identify and correct causes See 1-4, above. Cull high-SCC cows?

2 Mineral supplements? 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.

3 Bioplexed minerals? 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.

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MILK DROP AND POOR MILK YIELD IN COWS

MAIN CAUSES Comments

1 Infections Leptospirosis, viruses etc

2 Mastitis See Mastitis

3 Parasites Especially fluke and ostertagiasis

4 Metabolic disorders Hypomagnesaemia, ketosis, acidosis

5 Antibiotic contamination of feed Interference with ruminal microbial balance / digestion by lincomycin etc

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

7 Toxins Plant, fungal, chemical, excess Mg intake

8 Stress 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.

9 Low water intake Dirty water, saline- or heavily mineralised- water; water restriction

10 Miscellaneous disorders Lameness, pain, scour, respiratory disorder etc

11 Mineral deficiency 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.

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REMEDIAL ACTIONS to reduce the risk and severity of milk drop include:

Remedial actions Details

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

2 Check the water supply 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 10^oC, 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.

3 Mineral supplements? 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.

	MAIN CAUSES	Comments
1	Faults in the milking machine	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.
2	Management faults	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
3	Trauma	Trauma to udder and teats; rushing cows with pendulous udders
4	Periparturient problems	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
5	Mineral deficiency	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	Details
1	Identify and correct causes	See 1-4, above. Cull high-SCC cows?
2	Mineral supplements?	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.
3	Bioplexed minerals?	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.

	MAIN CAUSES	Comments
1	Infections	Leptospirosis, viruses etc
2	Mastitis	See Mastitis
3	Parasites	Especially fluke and ostertagiasis
4	Metabolic disorders	Hypomagnesaemia, ketosis, acidosis
5	Antibiotic contamination of feed	Interference with ruminal microbial balance / digestion by lincomycin etc
6	Inadequate feed	Reduced intake or quality of grass or silage; unpalatable herbage (reduced intake on certain paddocks, sometimes associated with high quality but low fibre)
7	Toxins	Plant, fungal, chemical, excess Mg intake
8	Stress	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.
9	Low water intake	Dirty water, saline- or heavily mineralised- water; water restriction
10	Miscellaneous disorders	Lameness, pain, scour, respiratory disorder etc
11	Mineral deficiency	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	Details
1	Identify and correct the causes	Check for, and correct, infection, mastitis, parasitism, metabolic disorders, antibiotic contamination of feed, inadequate feed, toxins, stress, poor water supply and miscellaneous disorders.
2	Check the water supply	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 10^oC, 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.
3	Mineral supplements?	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.