A LONGITUDINAL STUDY OF MASTITIS ON AN EXPERIMENTAL FARM WITH TWO HERDS, ONE MANAGED ORGANICALLY, THE OTHER CONVENTIONALLY
Thatcher, A., Petrovski, K., Holmes, C, Dowson, K., Kelly, T., McLeod, K.
Presented to the IFOAM Organic World Congress, Modena, June 2008
Dairy Cattle Research Unit
Massey University, New Zealand
Organic/conventional systems trial
• 2001: farm split, organic conversion starts organic 20.4 Ha 2.27 cows/Ha conventional 20.3 Ha 2.39 cows/Ha
• 2003: organic certification to EU standard
• 2006: organic certification to USDA standard (antibiotics excluded since 2005)
This project is the only comparative grassland-based open grazing dairy study in the world.
Both herds are milked through the same parlour into separate bulk tanks. Organic cows are milked first.
Management
• Seasonal supply (August to May)
• Pastoral based. Minimal supplements (typically <
10% of annual DM intake depending on weather) organic: grass silage, summer turnips
conventional: grass silage, maize silage, palm kernal expeller.
• Soil type difficult – poor draining compacted loess
• Organic pastures contain a wider range of species.
DCRU Monthly Pasture Growth
0 10 20 30 40 50 60 70
July September November January March May
kgDM/ha/day
Conventional Organic Figure 1: DCRU Comparative Pasture Growth, 01/07/03 – 27/05/04
Standard Mastitis Control Measures
• Seasonal Approach to Managing Mastitis (SAMM Plan) - based on Five Point Plan - applied to both herds
• Iodine-based teat spray with added emollient
• Milking machine kept in excellect condition
• Financial penalties for milk with BMSCC >
400,000
• Most common major pathogen in NZ is Streptococcus uberis followed by
Staphylococcus aureus.
Mastitis Study
• From November 2003, single quarter milk samples were taken aseptically from every quarter of all cows four times during the
season – at calving, 14 days after calving, mid-lactation, drying off.
• Additional data from daily bulk tank SCC,
monthly individual SCC, health records.
Results
• Bacterial growth data was subjected to an analysis of variance within each sample time.The differences were significant
generally only for Staphylococcus aureus.
• The organic herd recorded higher somatic cell counts than the conventional.
• Cows with high SCC were usually infected
with Staphylococcus aureus .
Results
• The pattern of infections by Staphylococcus
aureus and Streptococcus uberis was generally similar to recent data from conventional herds in New Zealand.
• The incidence of clinical mastitis for the first 3 seasons was higher than recent data for
conventional herds in New Zealand, but similar to reports in organic and conventional herds in the UK. In the last 2 seasons it has been lower.
0 2 4 6 8 10
1.12.03
2.03.04
2.06.04
2.09.04
3.12.04
5.03.05
5.06.05
5.09.05
6.12.05
8.03.06
8.06.06
8.09.06
9.12.06
11.03.07
11.06.07
11.09.07
12.12.07
13.03.08
Percent
Organic Conventional
Fig 2: Percentage of quarters culture positive to Streptococcus uberis
0 5 10 15 20 25 30 35 40
1.12.03
2.03.04
2.06.04
2.09.04
3.12.04
5.03.05
5.06.05
5.09.05
6.12.05
8.03.06
8.06.06
8.09.06
9.12.06
11.03.07
11.06.07
11.09.07
12.12.07
13.03.08
Percent
Organic Conventional
Fig 3: Percentage of quarters culture positive to Staphyllococcus aureus
0 50 100 150 200 250 300 350 400 450 500
12.08.03 20.11
.03
28.02.04
7.06.04 15.09.0
4
24.12.04
3.04.05
12.07.05
20.10.05 28.01.0
6
8.05.06 16.08.0
6 24.11.0
6
4.03.07
12.06.07 20.09
.07 29.12
.07 7.0
4.0 8
10 day rolling average BMSCC ( x 1000 )
Organic Conventional
Fig 4: Bulk milk SCC 2003 - 2008
Table 1: Percentage of cows with two or more monthly SCC greater than 400,000
Season 2003/04 2004/05 2005/06 2006/07
Organic 17 24 17 23
Conventional 20 17 8 15
Conclusion
• Control of S. aureus is likely to be the most important factor in managing mastitis in a pastoral-based organic herd
• Environmental pathogens are easier to control with adequate management of the cow’s
surroundings.
• The difficulty in eliminating S. aureus once well established in the udder means BMSCC may remain relatively high despite minimal spread of infection between cows
Management Strategies Strep uberis
• Note culture results are not an accurate
measure of infection (most positive cultures did not result in mastitis) – need to read
along with SCC.
• Critical to control is a clean environment around calving and drying off, good quality teat spraying, management of open teat
canals.
Management Strategies Staph aureus
• Principles: Prevent spread. If infected, mitigate SCC
• Teat spraying
• Monitoring of high SCC cows (RMT) - isolation from bulk tank
- supportive therapy
- post-milking stripping
Stress
Stress alone is not a cause of increased cell counts - unless there is an underlying infection.
When animals with subclinical infections are stressed there are often higher cell counts
U n in f e c t e d In f e c t e d U n s t r e s s e d 8 0 ,0 0 0 2 3 0 ,0 0 0 S t r e s s e d 1 0 0 ,0 0 0 1 ,0 0 0 ,0 0 0
Supportive therapies
Homeopathic regime
• Dried off with Lac caninum for 3 days.
• After 5 days treated with S.A (Staph aureus) nosode for 3 days.
• At calving, treated once a week with S.A. nosode for 3 weeks. If positive to milk culture, treated with the nosode for that bacterium for 3 days.
• Tonic drenches – ACV + garlic
• If there is a sudden rise in bulk SCC, immediate trough treatment with SA nosode for 2 days while the problem cow(s) are found.
• Complicating factor: every second day pick up!
Supportive therapies
Manuka Honey
• Dexcel trials indicate good cure rates for non invasive streps. For tissue invaders (ie most staphs), cure rates somewhere between self-cure and antibiotics
• Certified organic honey (UMF 10+) packed in 5ml syringes.
Treatment once daily for 4 - 6 days
• Total of 11 cows with elevated SCC (range 346,000 –
3,755,000) treated in Sept and Oct of the 04/05 and 05/06 seasons
• 8 showed a significant decline in SCC within 10 days of treatment. In 5 of these cases, SCC climbed again later in the season
• 2 appeared to cure bacteriologically
Key Control Measures
- an integrated approach
• Vigilance
- knowing the cows
- regular RMT of known high SCC cows
• A clean, stress-free environment
• High quality teat spraying (also ensuring teats are in good condition)
• Stripping of high SCC quarters
• Appropriate supportive therapy
• Careful culling
Acknowlegements
• The systems trial is funded by DairyNZ (formerly Dairy InSight)
• Staff at DCRU, NZ Veterinary Pathology and
Homeopathic Farm Support Services along with Natalie Butcher and Nicola Shadbolt
