Repeat breeding is one of the major causes of reproductive, productive and economic
losses in dairy sector. The main causes of repeat breeding include sub-clinical infection of
reproductive tract, age of the animal, error in the detection of estrus, endocrine dysfunction and
nutritional deficiencies. In Pakistan, a very high incidence of repeat breeding has been
documented (Kakar et al. 1997). In the past, intrauterine infusions have successfully been used
with a variety of antiseptic and antibiotic solutions. Meanwhile, therapeutic use of GnRH and
PGF2α has also been demonstrated to result in improved pregnancy rates. In particular, Ovsynch
protocol leads to an increase of 6-17% in conception rate.
The objective of the present study was to evaluate the reproductive efficiency with
antibiotic treatment during ovulation synchronization in repeat breeder Holstein Friesian cows.
This study was conducted on 30 pure bred Holstein Friesian cows kept under standard farm
conditions of feeding and management at Hussain Cattle and Dairy Farm, Kasur. The
reproductive efficiency of treated and control animals was based on ovulation rate, non-return
rate, conception rate, pregnancy rate, embryonic losses and luteal function. Results were
analyzed by independent T-test. A probability level of 95% was consider as significant (P<0.05).
All the experimental animals were screened to confirm non-pregnant and normal genitalia. Both
the treatment and control groups were synchronized using ovsynch protocol. Following first
injection of GnRH, the treatment group was subjected to intrauterine antibiotic infusion for five
days. On Day 7 of protocol both groups received an injection of PGF2α. At day 9 of ovsynch
protocol before second injection of GnRH both groups were scanned for ovarian status. Follicles
and CL measurement were noted and mapped by using 7.5 MHz trans-rectal probe (Honda
22
Summary
Model HS-1600) in both groups and second injection of GnRH was given. Timed artificial
insemination was performed after 16-20 hours of second injection of GnRH in both groups. After
8 hours of artificial insemination again ultrasonography was conducted to check the ovulation
rate in both groups, there was no significant difference between control and treatment, 60% and
75% of the animals in control and treatment groups ovulate respectively. At day 11 blood
samples were collected for progesterone assay. Non-return rate was visually observed at day 18
to 21 of artificial insemination. Blood was collected at day 18 for progesterone assay by puncture
of tail vein. After D28 andD42 of artificial insemination first and second pregnancy test were
conducted by using 7.5 MHz trans-rectal probe (Honda Model HS-1600) in control and treatment
group. There was a significant difference of pregnancy among the control and treatment group
by independent T-test. 3
rd
and 4
th
blood samples were collected for progesterone assay at day28
and 42 of artificial insemination in both groups respectively.