THE INFLUENCE OF MILK PRODUCTION ON OVARIAN CYCLICITY IN
PERIOD POSTPARTUM OF SIMMENTAL COWS
T. Dobranić, M. Samardžija, S. Vince, J. Grizelj, Vesna Dobranić, Nikica
Prvanović, Ž. Pavičić i D. Gračner
Veterinary faculty, Zagreb, Croatia
ABSTRACT
The influence of milk production on return of ovarian cyclicity in puerperium of
Simmental cows was the aim of research. It included the total of 25 cows at the ages of 2 to
10 years. We determined following metabolic parameters: glucose, total proteins, urea,
AST, ALT and creatine kinase and following hormones: progesterone P4 and IGF-I. Cows
were divided into two groups and examined gynaecological and by ultrasound. In the first
group of 13 cows the milk production was <25 L daily, and in the second group of 12 cows
>25 L. We took blood samples twice weekly from 4th till 45th day of puerperium. We
determined significantly higher level (P<0,001) for AST and ALT in group of cows with
higher milk production. However, we didn’t find significant differences (P>0,05) between
the groups in the level of proteins, urea, glucose and creatine kinase. The group of cows
with higher milk production the level of progesterone was 8,81±1,52 nmol/L, and the group
of cows with lower milk production it was 10,82±2,23 nmol/L. The group of cows with
higher milk production the level of IGF-I was 75,06±3,28 ng/mL, and in the group of cows
with lower milk production it was 81,36±2,03 ng/mL. We didn't find significant differences
between the groups (P>0,05) for progesterone P4, as well as for IGF-I. We concluded that
for the reestablishment of ovarian cyclicity in Simmental cows the milk production is not
of critical importance. Also that the combination of rectal and ultrasound examination, and
progesterone P4 and IGF-I serum concentration can precisely diagnose ovarian disfunctions
during puerperium.
ZUSAMENFASSUNG
The influence of milk production on return of ovarian cyclicity in puerperium of
Simmental cows was the aim of research. It included the total of 25 cows at the ages of 2 to
10 years. We determined following metabolic parameters: glucose, total proteins, urea,
AST, ALT and creatine kinase and following hormones: progesterone P4 and IGF-I. Cows
were divided into two groups and examined gynaecological and by ultrasound. In the first
group of 13 cows the milk production was <25 L, and in the second group of 12 cows >25
L daily. We took blood samples twice weekly from 4th till 45th day of puerperium. We
determined significantly higher level (P<0,001) for AST and ALT in group of cows with
higher milk production. However, we didn’t find significant differences (P>0,05) between
the groups in the level of proteins, urea, glucose and creatine kinase. The group of cows
with higher milk production the level of progesterone was 8,81±1,52 nmol/L, and the group
of cows with lower milk production it was 10,82±2,23 nmol/L. The group of cows with
higher milk production the level of IGF-I was 75,06±3,28 ng/mL, and the group of cows
with lower milk production it was 81,36±2,03 ng/mL. We didn't find significant differences
between the groups (P>0,05) for progesterone P4, as well as for IGF-I. We concluded that
for the reestablishment of ovarian cyclicity in Simmental cows the milk production is not
of critical importance. Also that the combination of rectal and ultrasound examination, and
progesterone P4 and IGF-I serum concentration can precisely diagnose ovarian disfunctions
during puerperium.
INTRODUCTION
It is vague why some dairy cows can produce great amount of milk and stay fertile
while the others do not (Taylor et al., 2003). However, it is generally accepted that the
higher milk production has no negative effect on ovarian cyclicity in puerperium as an
independent factor (Hackett et al, 1985). High milk production is often considered as a
main factor of negative energetic balance and causing later return of ovarian cyclity in
puerperium. Milk production, energetic and protein balance, age of cows, season of the
year, number of lactation and breed are considered the most important factors in different
duration of intercalving and servis-period in cows (Roche et al., 1992). Increased genetic
potential for milk production, as well as the changes in nutrition and herd size are
connected with lower cow fertility during lactation (Darwash et al., 1999). The aim of our
research was to establish the influence of milk production on return of ovarian cyclicity in
Simmental cows.
MATERIAL AND METHODS
During this research we divided 25 Simmental cows 2-10 years into two groups
based on their milk production. In first group of 13 cows daily milk production was <25 L,
and in second group of 12 cows it was >25 L. We performed ultrasound examination of
genital organs and took blood samples twice a week starting from 4th till 45th day of
puerperium. Samples were centrifuged on 3000 rpm during 10 minutes and collected sera
were stored immediately after, on -20°C till additional tests. We determined concentration
of glucose, total proteins, urea, activity of aspartate aminotransferase (AST), alanine
aminotransferase (ALT) and creatine kinase with standard spectrophotometrical usage of
kits and test reagents Olympus, Japan. Measuring the level of IGF-I (Biosource, Belgium)
and progesterone (Immunotech, France) was analysed with RIA method. All results were
analyzed with ANOVA and with Tukey’s tests post-hoc analysis.
RESULTS
We found significantly higher level (P<0,001) of AST (91,29±2,51U/L) and ALT
(21,60±0,49U/L) in group of cows with higher milk production comparing it with the group
of cows with lower milk production (AST (71,46±1,92U/L) and ALT (18,01±0,28U/L)).
However, we didn’t find significant differences (P>0,05) between the groups in the level of
proteins, urea, glucose and creatine kinase. In the group of cows with higher milk
production the level of progesterone was 8,81±1,52nmol/L, and in the group of cows with
lower milk production it was 10,82±2,23nmol/L. In the group of cows with higher milk
production the level of IGF-I was 75,06± 3,28ng/mL, and in the group of cows with lower
milk production it was 81,36±2,03ng/mL. We didn't find significant differences between
the groups (P>0,05) for progesterone P4, as well as for IGF-I.
DISCUSSION
There are opposite results between correlation of milk production and ovulation
failure. Harrison et al., (1989) did not establish differences in return of ovarian cyclicity in
cows with different milk production which is similar to our research results. Generally, it is
accepted that only high milk production has no harmful effect on ovarian cyclicity during
puerperium (Hackett et al., 1985). The same authors didn't establish the correlation
between milk production and duration of postpartal anoestrus or between milk production
of different cows with different ovarian cyclicity which is similar to our results. Opsomer et
al., (2000) also proved that the high milk production is not responsible for later ovarian
cyclicity. They proved that the energetic status is necessary for high milk production.
Hooijer et al., (2001) got opposite results because they found the correlation between high
milk production and ovulation failure. Ruiz et al., (1989) concluded that nutrition and milk
production are two most important factors connected to return of ovarian cyclicity in cows
during puerperium and consequentely with duration of intercalving and servis period. We
have not confirmed that in our research since there was no significant differences (P>0,05)
between the groups in levels of progesterone and IGF-I. Tennant, (1997) says that for
distinguishing liver diseases from skeletal injuries is necessary to determine the level of
creatine kinase as well as the AST activity in sera. Based on given results in both groups of
cows no liver diseases were found regardless to higher level of AST (P<0,001) in group of
cows with higer milk production. We can conclude that that the function of hypothalamuspituitary-ovarian axis will be reestablished in physiological period of postpartum. In group
of cows with higher milk production we established significantly higer level of ALT
(P<0,001) than in group of cows with lower milk production. Because, there were no
significant differences between groups in return of ovarian cyclicity we concluded that the
ALT level has no important diagnostic value which is similar to results of Boyd, (1983).
We concluded that for the reestablishment of ovarian cyclicity in Simmental cows the milk
production is not of critical importance. Also that the combination of rectal and ultrasound
examination, and progesterone P4 and IGF-I serum concentration can precisely diagnose
ovarian disfunctions during puerperium.
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