Basrah Journal of Veterinary Research,Vol.15, No.3,2016
Proceeding of 5th International Scientific Conference,College of Veterinary Medicine
University of Basrah,Iraq
254
GENETIC PARAMETER ESTIMATION OF DYSTOCIA VARIABLE IN
IRANIAN HOLSTEIN DAIRY CATTLE
Karami Maryam*, M.T.BeigiNassiri**, A.Nazari Nejad***; M. Chaji****,
H. Roshanfekr*****, B. Mohammad Nazari******
*Department of Animal science, Ramin Agriculture, and Natural Resources University,
Ahwaz, Iran
**Department Of animal science, Ramin Agriculture, and Natural Resources University,
Ahwaz, Iran
***Department of Animal science, Ramin Agriculture, and Natural Resources University,
Ahwaz, Iran
****Department of Animal science, Ramin Agriculture, and Natural Resources
University, Ahwaz, Iran
*****Department of animal science, Ramin Agriculture, and Natural Resources
University, Ahwaz, Iran
******.Animal breeding Research Center, Tehran, Iran
Keywords: Holstein dairy cows, dystocia, genetic parameter, heritability
ABSTRACT
The aim of this study was to estimated genetic parameters of dystocia variable in Holstein
dairy cows in Iran. For this purpose we used of data set that related to 734 herds of Holstein
cows in Iran that was collected from 24 years ago (between 1990-2014) by breeding center
and improve livestock production of Iran country. To study the structure of the data,
descriptive statistics and observations to correction effects we used of the SAS 9.1 statistical
software and GLM procedure. To obtain genetic parameters attribute dystocia we used of AI
REML procedures of WOMBAT software to analyzed univariate linear model and the results
obtained are as follows: Additive variance, residual variance, phenotypic variance and
heritability (±SE) for the first period of lactation, are 0.0045103, 0.029629, 0.034139,
0.132±0.003 respectively, for the second period of lactation are 0.00063452, 0.073695,
0.074329, 0.009±0.002 respectively and for third period of lactation are 0.00036919,
0.073817, 0.074187, 0.005±0.001 respectively was estimated. In all three lactation periods
we can seen that lowest percentage of dystocia was occurred at age 27 to 28 months 18.66%,
between the ages of 28 to 38 months 10.14% and for ages 40 to 51 months 9.61% and by
Basrah Journal of Veterinary Research,Vol.15, No.3,2016
Proceeding of 5th International Scientific Conference,College of Veterinary Medicine
University of Basrah,Iraq
255
considering Cochran Armitage test results we can determined that the difference between the
classes for this trend is significant statistically(p<0.0001).
INTRODUCTION
The cows, That don’t have access to sufficient energy in their ration can getsickness(1;2;
3). Milk production has a high priority in metabolism of dairy cows so lactating cows are
more prone to get sick for example infertility than dry cows. This can ruin all the benefits of
higher milk yield because of the higher prevalence of the disorders (4 ;6; 7). There is an
extensive controversy among researchers about that and the proof of this hypothesis is so
difficult. Although some scientists have shown these correlations (6; 7; 8) but the hypothesis
of high correlation between higher milk yield and occurrence of the disorders is not
completely clear. Dohooand Martin(5) have shown that milk fever was the only disorder that
has relation with milk yield among their 17 controlled disorders. They couldn’t find any
relationship between other controlled disorders like dystocia, retain placenta, metritis and
ovarian cysts. Therefore with providing good management and nutrients sufficiency the high
milk yield is not a risk factor for disorders. The Aim of study was to know the effect of
higher milk yield as a risk factor of disorders and estimated genetic parameters of dystocia
variable in Holstein dairy cows.
MATERIAL AND METHODS
Data of this research has gathered from veterinarians weekly visits to dairy cows herds in
Iran. Data for this research had gathered from 734 herds with 1655244 Holstein-Frisian cows
which had parturition among 1990-2014 by breeding center and improve livestock production
of Iran country.Data were from three lactation period. Two classes of groups disorders have
been analyzed. They are as follow: group dystocia positive(1) and health group(0). Each
model consist of milk yield, parity, year (age) of calving to determine the correlation between
Basrah Journal of Veterinary Research,Vol.15, No.3,2016
Proceeding of 5th International Scientific Conference,College of Veterinary Medicine
University of Basrah,Iraq
256
milk eield, parity,year of calving and occurring of disorders data have been analyzed with
univariatelinear model. In this research current lactation was used as the lactation with
occurrence of particular disorder (dystocia).To study the structure of the data, descriptive
statistics and observations to correction effects we used of the SAS 9.1 statistical software
and GLM procedure. To obtain genetic parameters attribute dystocia we used of AI REML
procedures of WOMBAT software to analyzed Univariate linear model.
RESULTS
The results obtained are as follows: Additive variance, residual variance, phenotypic
variance and heritability (±SE) for the first period of lactation, are 0.0045103, 0.029629,
0.034139, 0.132±0.003 respectively, for the second period of lactation are 0.00063452,
0.073695, 0.074329, 0.009±0.002 respectively and for third period of lactation are
0.00036919, 0.073817, 0.074187, 0.005±0.001 respectively was estimated. In all three
lactation periods we can seen that lowest percentage of dystocia was occurred at age 27 to 28
months 18.66%, between the ages of 28 to 38 months 10.14% and for ages 40 to 51 months
9.61% and by considering Cochran Armitage test results we can determined that the
difference between the classes for this trend is significant statistically(p<0.0001).According
to performed analysis on all cattles (heifers and the cows with several parturition) higher milk
yield was not a risk factor for the disorder.
DISCUSSION
Lots of bias factors in researches exist about the correlation of milk yield and occurrence
of the diseases that makes these relations unclear. For example elimination of low milk
producers with mastitis and saving the high producers with the disease could produce a
correlation between mastitis and high production but it could be false. With our knowledge,
there is not many research about the relation of milk yield and diseases. It should be noted
Basrah Journal of Veterinary Research,Vol.15, No.3,2016
Proceeding of 5th International Scientific Conference,College of Veterinary Medicine
University of Basrah,Iraq
257
that milk yield is not the only risk factor of diseases. Occurrence of a particle illness can have
managementaland conditional reasons but understanding of all factors and their importance is
something hard to do even with modern digital and computerized technologies, so, it is not
simple to evaluate the interaction between different factors. There are some biases in
evaluating the correlation between milk yield and occurrence of the illnesses. One of these
biases is finding the sick animal and treatment or omitting of them by the animal owner
himself and so not observing of that by veterinarians (7).Our outcomes showed a negative
correlation between dystocia with parturition. Analysis of correlation between prevalence of
the disorder and parturition showed a negative correlation. Parity had a negative correlation
with dystocia, and a positive correlation with lowest age. The year of calving had a
significant correlation with dystocia.
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