Page 23 - ACV Journal DECEMBER 2015

Scientific
TACKLING A STREPTOCOCCUS UBERIS
MASTITIS PROBLEM USING THE
COUNTDOWN DOWNUNDER MASTITIS
INVESTIGATION PACK
Steph Bullen, Maffra Veterinary Centre and University of Melbourne Dairy Resident
Key points:
• Countdown Downunder Mastitis Investigation Pack is freely
accessible online
• Suitable for veterinarians of all experience levels to guide
mastitis investigations
• Enabled successful investigation of a S. uberis problem in
dairy herd near Maffra
• Implementation of recommendations resulted in dramatic
improvement in BMCC
• A collaborative effort between factory field staff and
veterinarians was beneficial
Introduction
The mastitis investigation reported here was conducted as a case
study for the Countdown 2020 Adviser Short Course held in Milawa
in May 2015. The group of investigators consisted of two factory field
officers and two relatively recently graduated veterinarians. As the
group members had limited experience in conducting herd mastitis
investigations, the Countdown Downunder Mastitis Investigation Pack
(MIP) was used to structure the investigation and improve the likelihood
of a solution being achieved.
Background
The case study farm was identified by the factory as a bulk milk cell
count (BMCC) “high flyer” and was at risk of losing the supply contract
if immediate action to address the milk quality issues was not taken. The rate in heifers was not interpretable due to the low number of heifers (n
farm is a seasonally calving (calving start date 1st August) herd milking = 26). No ICCC data was available for previous lactations.
110-130 predominantly crossbred cows. The “Farm Profile” (Section
B1 of MIP) identified the following:
• No employed labour – farm owner only
• Whole herd dried off late May
• Goal to grow herd to 150 cows
• Herd recording commenced at the start of the 2014 calving
season
• Shed is a high-line 15-unit herringbone (swingover) with
DeLaval shells and liners
• High incidence of clinical milk fever (>60 cows treated with
a number of associated deaths)
• No specialized transition cow management currently
• Selective dry cow therapy (DCT) based on cases of clinical
mastitis) was used prior to 2014 dry-off
www.ava.com.au/cattle
• No water troughs in paddocks – one central trough near the
dairy
Figure 1 shows the farm’s BMCC history since the start of the 2012
season. The farm owner believes his mastitis problems commenced
following a flood event in May 2014. However, his BMCC history
suggests that this problem has been ongoing since at least December
2012. The BMCC is high throughout lactation and does not appear
to be associated with calving periods. It is estimated that the BMCC
being outside of premium payments has cost this farmer in excess of
of $18,772 in the 2013/2014 financial year in milk quality deductions
alone and does not include lost production, risk of clinical cases, culling
or any other factors).
Milk cultures
Mycoplasma bovis and S. agalactiae were not present in the bulk milk on
11/3/15 (4-pathogen PCR). Individual infected quarters (identified using
the Rapid Mastitis Test; RMT) of high ICCC cows (>300,000 cells/ml)
from the most recent herd test were sampled for microbial culture and
sensitivity. 29 samples in total, including four farmer-collected samples
from clinical cases were submitted. Of these, 21 cultured Streptococcus
uberis and four cultured Staphylococcus aureus.
Herd recording
Herd recording data was obtained from the herd test centre as a zipped
diff file and uploaded into DairyData (Version 6; Warnambool Animal
Production Services; Australia) for individual cow cell count (ICCC)
analysis. The monthly prevalence of subclinical mastitis (ICCC >250
000 cells/ml) was calculated and varied between approximately 30-
60% across the herd this season as shown in Table 1. The new infection
Table 1.
Subclinical mastitis (ICCC >250 000 cells/ml) prevalence in the case
study herd
Milking machines
An AMMTA dry test conducted at the beginning of the season did
not identify any problems with the plant. “Performance of Milking
Machines” (Section F of MIP) was conducted under the supervision of
two experienced veterinarians (Dr Jakob Malmo & Dr Mark Humphris)
utilizing both the DairyTest Professional and VaDia devices. The mean
The Australian Cattle Veterinarian | volume 77 | December 2015 23