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Research
1.
Epidemiological
studies on subclinical mastitis in dairy cows in Assiut governorate
-
Ahmed Abdel-Rady and Mohammed
Sayed
Veterinary
World 2(10):373-380
Abstract
In this
investigation, some epidemiological studies were run
on subclinical mastitis for totally 350 dairy cows
of different breeds, ages and distributed in
different villages in Assiut governorate, Assiut,
Egypt, along a whole year (during the period from
June 2006 till July 2007) through field screening
surveys by using of the California mastitis test
(CMT) for each quarter milk sample followed by
bacteriological examination to identify the major
causative agents of intramammary infection (IMI).
The dairy cows were differed from the breed point of
view as 230 Holstein Friesian breed and 120 native
breed. Also, they were differed from the age point
of view as a group of 95 cows aged from 2 to 4 years
old and another group of 255 cow aged from 5 to 8
years old. All dairy cows were apparently healthy
with clinically sound udder secreting apparently
normal milk. All the cows lived nearly under the
same conditions of breeding from the habitat,
hygiene and feeding systems. The obtained results
revealed that 67 cows (19.14%) had 80 infected
quarters (5.71%). It was found that the most
frequently major causative agents isolated were
Staphylococcus aureus, Streptococcus agalactiae and
Escherichia coli from the positive CMT samples with
prevalence 52.5, 31.25 and 16.25%, respectively.
With studying the breed factor, it was found
Friesian breed was sensitive towards infection
(20.43% at the cow level and 6.09% at the quarter
level) than of native breed (16.67% at the cow level
and 5% at the quarter level). It was also noticed
that the prevalence of subclinical mastitis in hot
weather as during summer (9.14% at the cow level and
2.64% at the quarter level) and during spring (4.86%
at the cow level and 1.36% at the quarter level) was
higher than in cold weather as during winter (2% at
the cow level and 0.64% at the quarter level) and
during autumn (3.14% at the cow level and 1.07% at
the quarter level). In relation to age
susceptibility, 5-8 years old cows (15.43% at the
cow level and 4.36% at the quarter level) were
susceptible than those of 2-4 years (3.71% at the
cow level and 1.36% at the quarter level). The
degree of quarter attack according to positive CMT
was varied from 35 quarters (2.50%) showed degree
(+++), to 45 ones (3.22%) showed degree (++), to 120
ones (8.57%) showed degree (+) and the rest (85.71%)
showed degree (-). The obtained results threw the
light on the epidemiology of subclinical mastitis in
Assiut villages and provided an importance of the
CMT for diagnosis of subclinical mastitis due to it
is a reliable, easy, rapid and cheap tool helping in
diagnosis and controlling the disease because it
directs attention to individual mammary quarter that
is secreting milk of high somatic cell content
(SCC). Programs for control of subclinical mastitis
may be planned around the routine examination of all
lactating cows, and consequently early treatment can
be applied towards positive cases rapidly for
preventing their conversion towards clinical form
among dairy cows and for protecting the herd health,
milk hygiene and consequently the consumer health.
Key words: Epidemiology, Subclinical
mastitis, California mastitis test (CMT),
Intramammary infection, Dairy cows.
