Subclinical mastitis in small ruminants: prevalence, comparative aspects and prevention

, LeitnerDr. Gabriel National Mastitis Reference Center,Kimron Veterinary Institute, Israel

Dr. Nissim SilanikoveDepartment of Animal Physiology,

Agricultural Research Organization,The Volcani Center, Israel

Welfare

Is subclinical mastitis of concern to the small ruminant industry?

Zoonosis agents* brucellosis* tuberculosis

Milk quantity?Yield of milk, fat, total proteins,

casein and curd

Milk quality?Internal bacterial contamination,

somatic cell count, secreted enzymes

Economic question

Subclinical mammary infectionis an economical question

In most herds most of the time the proportion of infected animals

is unknown

Cost benefit

* Cost of identification

* Loss of yield, quality

* Cost of treatment 

Cost benefit

* Cost of identificationHerd              individual  

Bulk SCC  BacteriologySCC, CMT 

Bacteriology ‐

Laboratory costSCC – No routine measurement CMT – Low cost; animal place

Parturition Drying off 

CMTSCC (x 1000)Bacterial status

0-150- 300Uninfected2-4> 500Infected

Cells in

 milk

High infection periodTesting periods

* Loss of yield, quality

Aim: to calculate the loss of milk and cheese as related to the level of subclinical udder infection in a herd.

To clarify the major factors that influence milk yield and, consequently, curd yield in Assaf sheep and Saanen and Shami × Anglo-Nubian goats.

Sheep

1217812760,00025243415251,300,00050365123382,100,00075

Goat

162138640,000253241615920,0005048628231,300,00075

HerdHalf-udder model

Herd Half-udder model

Total curd loss (%) Milk loss (%)ProjectedSCC

Infection rate

Leitner

G. 

et 

al. 

(2008). 

Estimate 

of 

milk 

and 

curd 

yield 

loss 

of 

sheep

and 

goats 

with  intrammamary

infection 

and 

its 

relation 

to 

somatic 

cell 

count. 

Small 

Ruminant 

Res.,  74:221‐225

Animal model built on glandular level

One udder-half infected with CNSspecies and the contra-lateral beingfree of bacteria

+ -

S. capraeS. chromogenesS. epidermidisS. simulansS. xylosos

Sheep and goats were considered infected onlyif the same bacteria was isolated and SCCwas high (> 106) in three consecutive samples

Most udder-halves infected with CNS had a normal morphology, similar to the contra-lateraluninfected gland

Number of udder infectionBacteria

Sheep Goat 8 45S. aureus

78 28S. chromogenes277 171S. epidermidis68 97S. simulans21 36S. xylosus- 77S. caprae31 8Streptococci10 15Coliforms29 12Corynebacteria spp.

522 (33%) 489 (35.9%)Total infected

29 12Total uninfected

* Milk yield was measured separately for each udder-half

* Milk tested for: bacteriology, SCC, protein, fat, lactose

* Skim milk was analyzed for: casein, whey protein, albumin, proteose-peptone, and activities of Plasmin, Plasminogen activator and Plasminogen, ionized calcium(Ca2+) and calcium activity (aCa2+)

* Curd yield and Rennet clotting time

00.20.40.60.8

11.21.41.61.8

2

Uninfected Infected

SheepGoatKg

/ day

Milk yield (half) of sheep or goat infectedwith CNS species in one gland

and the contra-lateral being free

Sheep: - 0.81 Kg/dayGoat: - 0.58 Kg/day

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

Uninfected Infected

SheepGoatSC

C SCC (half) of sheep or goat infected

with CNS species in one gland and the contra-lateral being free

Sheep: + 2,088,000Goat: + 1,333,000

Parameter Sheep Goats

Uninfected Infected Uninfected Infected

Fat (g/L) 64.9±0.26 61.7±0.21 38.9±1.1 38.8±1.2

Protein (g/L) 58.5±0.07 53.5±0.10 34.2±0.5 35.0±0.5

Casein (g/L) 45.9±1.36 40.5±1.59 28.1±0.7 28.2±0.8

Lactose (g/L) 44.7±0.08 33.5±0.16 47.0±1.0 41.7±1.3

Whey (g/L) 11.9±0.38 12.8±0.16 6.1±0.3 6.8±0.4

Albumin (µg/mL) 517±31 759±59 280±22 472±50

Mean and SE of fat, protein, lactose, whey, casein and albumin in uninfected vs. infected

glands of sheep and goats.

0

0.5

1

1.5

2

2.5

Uninfected Infected

SheepGoatp -

p , g

/ LProteose-peptone concentration

Sheep + 247%, P < 0.0001Goat + 151%, P < 0.0001

Rennet clotting time of goat and sheep milk from uninfected vs. infected udder-halves

Goat Sheep0

50

100

150

200

250

300

350

400

450

500

Ti

me

(sec

)

Uninfected Infected

Curd yield of goat and sheep milk fromuninfected vs. infected udder-halves

0

5

10

15

20

25

30

35

SheepGoat

Uninfected Infected

C

urd

yiel

d (g

/L)

NO Infection  Infection 

Cost benefit

* Cost of treatment   

Parturition Drying off 

Cells in

 milk

Testing periodsTreatment

Treatment is a choice:* Bactria sensitivity* Medicine exist* Cost benefit  

Aim: determine dry-off treatment inAssaf sheep:

efficacy and a management tool forimproving milk quantity and quality.

Results

Sheep

%Number47.5%151/318Total infected halves

88.7134Total CNS17.223S. chromogenes50.067S. epidermidis3.04S. haemolyticus17.924S. simulans3.04S. xylosus8.912Unidentified CNS

IsolationsBacteria

Distribution of intramammary bacterialfindings in 159 dairy sheep (318 halves) at drying-off.

Results

Sheep

Distribution and [2] results of 159 dairy sheep udders (318 halves) before draying-off and 21-28 days post-partum, according to udder

bacterial infection.

Bacteria

P (2)NoYesBacteria

65 (71%)27 (29%)92YesTreatment

< 0.00018 (8%)54 (92%)59YesControl

57 (81%)13 (19%)70NoTreatment

NS70 (72%)27 (28%)97NoControl

After treatmentBefore treatmentGroup

Results

Sheep

Average milk yield, bulk-milk somatic cell count and percentage infection in the sheep flock in the course of the 2-yr study.

2 0 0 3 2 0 0 4 2 0 0 53 8 0

4 0 0

4 2 0

4 4 0

4 6 0

4 8 0

5 0 0

Y e a r

Ave

rage

milk

yie

ld (s

heep

lact

atio

n-1)

2 0

2 5

3 0

3 5

4 0

4 5

5 0

5 5Flock infection (%

)

Bulk tank som

atic cell count (x 1000)

8 0 0

1 0 0 0

1 2 0 0

1 4 0 0

1 6 0 0

1 8 0 0

2 0 0 0

2 2 0 0

2 4 0 0

2 6 0 0

- Average milk yield,

- somatic cell count,

- percentage intramammary infection.

Results

SheepMilk yields of uninfected and infected ewes.

0 2 5 5 0 7 5 1 0 0 1 2 5 1 5 0 1 7 5 2 0 0 2 2 50 .0

0 .5

1 .0

1 .5

2 .0

2 .5

3 .0

Milk

(L d

ay-1)

D a y s in m ilk

- uninfected,

- infected.

Cost benefit

Cost of identificationTime of sampling ‐

second week in lactation 

and/or before drying off.

Test

‐

CMT and/or SCC and bacteriology 

Improved milk yield quantity and quality of products 

Cost benefit

Loss of yield, quality Milk Yield –

reduction of 5‐30% 

Product quantity and quality 

‐

reduction of 5‐30%

Reduction dependent on bacteria  spices and animal’s breed  

Cost benefit

Cost of treatment Recovery – 50‐85% 

Existing Medicine –

availability and price 

Recovery

depends on bacteria  species and length of the infection 

Prevention

Identification

Subclinical mastitis 

Existing medicine, availability and price

Calculate  cost benefit

Thanks