IMPACT OF BRUCELLOSIS AND OTHER FACTORS TO THE CALVING INTERVAL OF
DAIRY COWS IN BORDER AREA OF KLATEN AND BOYOLALI
Ely Susanti1*, Widagdo Sri Nugroho2, Agung Budiyanto3
1 Postgraduate student of Veterinary Science Faculty of Veterinary
Medicine Gadjah Mada University, Staff of Department of Agriculture in Klaten
District,
2 Veterinary Public Health Department, Faculty of Veterinary
Medicine, Gadjah Mada University,
3 Obstetrict and gynecologi Department, Faculty of Veterinary
Medicine, Gadjah Mada University,
ABSTRACT
Brucellosis is an endemic disease in Indonesia,
which has been influence to the reproduction performing of cows. Border area of
Klaten-Boyolali has a high risk of infecting brucellosis due to high cattle
traffic in both districts. This study aims to investigate the effect of
brucellosis and other risk factors to calving intervals on dairy cows in
Klaten.
This cross-sectional study involved three
hundred and fifty three dairy cows from one hundred and forty six farmers. Brucellosis
was diagnosed using RBT and CFT. Calving interval datas were collected
base on farmers’ recording, the risk factors were obtained by questionnaires
include: general information, typology of the farmers, the type of cows, the
number of cows, farming management, the farmers’ knowledge, and the cow’s
individual data.
Eleven of three hundred and fifty
three dairy cows (3.1%) suffered brucellosis, but it did not impactt to the
calving interval performance. Some factors that prolonged the calving interval,
those factors were:cows’ first postpartum estrus, metritis history; abortion in
the third trimester of pregnancy, the cows are from Jatinom Market. On the
other hand, not having brucella vaccine reduces the dairy cows’ calving
interval length.
Keywords: brucellosis, dairy
cows, calving interval, risk factors, Klaten
- INTRODUCTION
According
to Director General of Animal Husbandry Regulation No. 59 / 2007, brucellosis
is one of twelve strategic contagious animal diseases. Brucellosis
is also one of the most important zoonotic diseases in the world. Brucellosis
causes a decrease in milk production, abortion, weak newly born calves, weight
loss, infertility and disability. Brucellosis is also a major inhibiting factor in the livestock
trade. Therefore, it is also a disease with considerable economic impact
(Bernues et al. 1996 and Rompis, 2002).
In cattle, brucellosis mainly infects cows. Bulls can also be
infected but they do not directly spread the disease. Brucellosis in cattle is caused by the Brucella abortus bacterium which
causes abortion in the last trimester and infertility. Brucellosis is an endemic disease
in Indonesia, it spreads in almost all provinces.
Dense area of dairy cows in Klaten District has a high risk of
having brucellosis, because it borders on the district of Sleman and Boyolali
District, which are believed to have a high incidence of brucellosis. There is
no official information on the prevalence of brucellosis in Boyolali and Sleman
district until now. Kemalang, Karangnongko, Jatinom, and Tulung Sub District
have a high traffic for dairy cows and dairy cow trade into Boyolali Livestock
Market. It is one of the largest livestock markets in Central Java. As a result, the possibility of getting the
animals infected by the disease is quite high. This study aims to investigate
the effect of brucellosis and other risk factors to the calving intervals of
dairy cows at Klaten District area, which has a high risk to be infected by the
disease.
- RESEARCH METHODOLOGY
2.1
Research Sites
The
study was conducted at Klaten District, the area which has a high risk to be
infected by brucellosis, has a high population of dairy cows, and borders on
Boyolali District. The sites are Kemalang, Karangnongko, Jatinom, and Tulung
Sub District.
2.2 Data
Collection
A
semi-structured questionnaire is used to collect information which was relevant
to the investigation of the epidemiology, such as typology of farmers,
farmingexperience, type of cattle, farming management system, cattle density,
and data covering cattle’s origin, age, vaccination status, gender, and
reproductive performance. Before
the study, the questionnaires are delivered to some respondents to test their
validity and reliability.
2.3
Study Design
Cross-sectional
epidemiological studies are used to investigate the effects of brucellosis and
its risk factors to the calving interval. To calculate the sample size, the
formulas of Martin et al., 1988, is used, n = 4PQ/L2. Ninety five per cent
confidence level and five per cent error are desired. The temporary prevalence
used was the prevalence of Laboratory Type B survey results in Surakarta,
Central Java Province, which is 2.617%. Total sample are two hundred and eighty
six cows. Assuming that each farmer has two cows, the sample consists of one
hundred and forty three farmers
2.4 Sampling Method
The
sampling method used is a dual stage, simple random, proportional, and
clusters. Blood specimens are collected from all cows owned by elected farmers.
In this study the amount of blood specimens are obtained from three hundred and
fifty three dairy cows from one hundred and forty six farmers. Serum screening
for brucellosis are tested by using RBT, RBT positive serum and further by CFT.
2.6
Research Variables
The
variable in this study are the calving interval as the dependent variable (X),
and the factors that are assumed to have a relationship with the incidence of
brucellosis as an independent variable (Y).
Screening
test consisting RBT and the CFT confirmation test are used in this study.
Any samples that showed positive results in RBT
will be followed by CFT as a confirmation test. Both tests are conducted in
Disease Investigation Centre (BBV) Wates.
2.8 Data Analysis
Data
collected from the questionnaires and laboratory tests are processed by
multivariate analysis using software Statistix for Windows Version 7. Linear
regression models are used to determine the effect of brucellosis and other
factors on calving interval.
3.
RESULTS
The results of factor analysis calving intervals without intervention
of variables.
Table 1. Linear regression analysis of calving interval
UNWEIGHTED LEAST SQUARES
LINEAR REGRESSION OF CALVINTER
PREDICTOR
VARIABLES
COEFFICIENT STD ERROR STUDENT'S T P
VIF
CONSTANT 12,5617 0,94942 13,23 0,0000
ESTRUSI 0,79597 0,07305 10,90 0,0000 1,0
METRITIS 1,89004 0,88030 2,15 0,0328 1,1
SC 0,92946 0,11885 7,82 0,0000 1,1
SEMBLNBUL 2,01464 0,70320 2,86 0,0046 1,0
TINOM 3,02256 1,14407 2,64 0,0088 1,0
VAKSINBRU
-2,71876 0,82776 -3,28 0,0012 1,0
The analysis shows the value of Adjusted R-squared (Adj.R ²) is
0.4967. Constant confidence level is 0.000 and the test results with the
Wilk-Shapiro Approximate is 0.9016 (Figure 1).
After that CFT
variable is forced. The result is the level of confidence for CFT variable is
0.645 and its Adj. R ² is 0.4949. Moreover, its test results with the
Wilk-Shapiro Approximate amount is 0.9006, with the image of regression
residual plot in fanning shaped and left-leaning histogram.
To obtain a better model, a transformation is carried out on the
dependent variable by using the inverse transformation, BCALVIN = 1 /
(CALVINTER). Transformed dependent variable model appear better than the model
before the transformation. Adjusted R-squared value (Adj.R ²) becomes 0.5149.
Constant confidence level is 0.000 and the test result with the Wilk-Shapiro Approximate
is 0.9690. In this equation the function used is the inversed transformation, BCALVIN = 1 / (CALVINTER). The result of
the transformation model is better than the one before the transformation but
it cannot be applied in the field.
As a consequence the model applied in the field is the model
before the transformation. The equation model obtained for the calving interval
is based on linear regression analysis before transformation, which is:
CALVINTER = 12,5617+ 0,79597 ESTRUSI + 1,89004 METRITIS +
0,92946 SC + 2,01464 SEMBLNBUL + 3,02256 TINOM - 2, 71876VAKSINBRU
Picture 1. Approximate
Wilk-Shapiro calving interval
4. DISCUSSION
The first postpartum estrus (ESTRUSI) is positive on calving
interval (+ 0.79597). The late appearance of first postpartum estrus will add
the value of the cows’ calving interval - the later the first estrus, the
longer the calving interval. This is in accordance with the reproductive cycle
– the period needed for the estrus is proportional to the period needed for the
calving interval. The length of the calving interval is the accumulation of the
period needed for the emergence of the first estrus until the breeding and the
period of the pregnancy (Bath, 1985 and Parkinson's disease and Barrett, 2010).
In addition, Lobago (2007) explains that the calving interval has two
components, the calving-to-conception interval and period of pregnancy.
Calving-to-conception interval is related to the return of the cow’s estrous
cycle and the accuracy in the estrus detection.
Reproductive health has a positive relationship to calving
interval. Cows suffering from metritis will increase their calving interval for
1.89004 months. Cows suffering from metritis will take time for recovery. As a result, the calving interval of the cows
suffering for metritis will be longer than the ones which do not suffer for
metritis. Some previous studies describe that metritis can reduce pregnancy
rate up to 30%, while the clinical endometritis can lower pregnancy rate of
27%, and subclinical endometritis can reduce pregnancy rate up to 51% (LeBlanc,
2005). While suffering metritis, the uterus does not support the development of
the embryo properly. As a consequence,
the embryo will die in a short period of time after the conception. A small
number of abortion caused by metritis happen at 2-4 month pregnancy. Although
metritis can be cured, the cow’s fertility cannot be as normal as it was before
suffering for metritis. Moreover, its mean for SC will be higher than before
which may cause abortion, salphingitis or even sterile (Parkinson, 2010). In
addition, metritis causes irregular estrous cycles (Bath, 1985). Therefore, the
cows which suffer for metritis have longer reproductive cycle than those which
never suffer for metritis.
Preconception service has positive value in 0.92946 for calving
interval. Cows that have 1 value of SC will add calving interval period of
0.92946 x 1 month. The bigger the value of SC a cow has, the longer period of
calving interval it has. To achieve the ideal calving interval (12 months), the
SC must also be ideal, which is once. In the reproductive performance of dairy
cows, preconception service will always be proportional to the calving interval
(Parkinson and Barrett, 2010). The period between the last time the cow gives
birth up to a successful breeding resulting in pregnancy depends on the success
of the breeding. Lobago (2007) explains that inefficiency of estrus detection
is one of the factors that lead to the longer calving intervals. The accuracy
of estrus detection and insemination time determine the success of conception
(Stevenson, 2001 and LeBlanc, 2005).
Incidence of abortion in the third trimester of gestation
(SEMBLNBUL) associates positively to calving interval. The cows having abortion
in the third trimester have their calving interval increase by 2.01464.
Abortion in the third trimester of pregnancy means increasing the length of the
calving interval of at least six or seven months. If the cows have given birth
three times or more, each calving interval will increase up to one or two
months. Another possibility is that the length of calving interval is an
indirect effect of the factors that cause abortion. Some factors that cause
abortion are trauma, nutrition or infection, which may lead to the disruption
of reproductive functions (Parkinson, 2010). Abortion can initiate the
metritis, placenta retention, and temporary infertility in cows, which increase
the length of calving interval (Mangen et al., 2002, Asmare et al., 2010, and
Megersa et al., 2011).
The cows from animal market Jatinom (TINOM) have a positive
influence on calving interval. Every cow that comes from the animal market
Jatinom has increasing calving interval to 3.02256 months. Jatinom market is a
major destination market for the trading of beef cattle, only a small amount of
dairy cattle are traded there. The dairy cows from Jatinom Market are the
result of cross breeding with beef cattle, so there can be an alternation of
the cows’ reproductive function compare to the one with the pure line.
Praharani et al. (2010) explains that the reproductive performance of Friesian
Holstein cows from cross breeding with Ongole are lower than the Friesian
Holstein cows - in this case the
parameters used are the pregnancy percentage and the period of postpartum
estrus. Cow breeding is associated with
reproductive performance especially on conception rate, conception rate
differences will cause differences in pregnancy rate and calving interval
(Dillon et al., 2003).
The status of vaccination against brucellosis (VAKSINBRU) has a
negative effect on calving interval. Cows which are not vaccinated by
brucellosis vaccine will have reducing calving interval of 2.7 months. In
contrast, if the cows are vaccinated, the calving interval will increase. In
conclusion, it is better to not having the cows vaccinated so that they have
longer calving interval. Brucellosis vaccination was done six months ago, at the
time of interview, by S-19 type of vaccine. The vaccinated cows were not
pregnant. S-19 vaccines were given to mature cow to gain immunity against
brucellosis. The effect of S-19 vaccination is the persistent antibodies in the
cattle (Lopez, et al., 2010). The data obtained indicate that all the vaccines
used in the study area is the S-19 brucellosis vaccine and only thirteen cattle
that have been vaccinated are included in the study. Every cattle vaccinated
with the S-19 will have a positive reaction to the RBT (Samartino et al. 2000).
Table 18. shows that there are six cows that have been vaccinated but do not
lead to brucellosis positive RBT. The effect of S-19 vaccination occurs on the
pregnant female, which may cause abortion (Monreal et al., 2003).
Six variables in the model of linear regression analysis are first
estrus postpartum, metritis, SC, abortion in the third trimester of pregnancy
age, the cattle’s origin (from Jatinom Market) and brucellosis vaccination
status. These variables must be considered in order to increase livestock
productivity by minimizing calving interval. The results of linear regression
analysis also showed that there is no effect of brucellosis on calving
intervals of dairy
cows.
5. CONCLUSION
There is no effect of brucellosis on calving interval. Calving
interval of dairy cows in the study are affected by the first postpartum
estrus, metritis, SC, abortion in the third trimester of pregnancy, the
cattle’s origin (from Jatinom Market) and brucellosis vaccination status.
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