Oral and Poster Abstracts

clear intraluminal mucus, and in 5 cases purulent endometritis was
found. In contrast, only two uteri were without any histopathological
findings. Histological alterations, varying in quantity and quality,
could be detected in 116 uteri: 101 cows showed a periglandular
fibrosis (“bovine endometrosis”), 84 angiopathies, and 72 an
endometritis, mostly nonpurulent. In most cases (n=104), several
alterations occurred simultaneously. Due to sampling artefacts, only
77 of 98 biopsies could be examined histologically. In 48 of 49
cases, at least one of both biopsies was evaluable. There is a farranging
conformity comparing the findings in biopsy with those in
uterine samples, collected post mortem. These results indicate that
the majority of sub-/infertile cows without further clinical symptoms
has endometrial alterations visible in endometrial biopsy.
Nevertheless, in order to establish the potential diagnostic tool
“endometrial biopsy” in buiatrics as a prognostically meaningful
method, further investigations, especially in clinically healthy and
fertile animals with a detailed documented reproductive status, are
necessary.
Key words: cattle, reproduction, endometrial biopsy, infertility, uterus
375 The Effect of Buserelin and an Opioid Antagonist on
Pregnancy Rate of Repeat Breeding Holstein Dairy Cows
V. Fuentes, A. Bernal, J. Olmedo
Universidad de Guadalajara, Centro Universitario de los Altos,
Tepatitlan Jalisco Mexico, Mexico
The objective of this study was to observe the effect of buserelin and
naloxone in repeat breeder Holstein dairy cows. In a double blind
study 45 repeat breeder Holstein cows were selected from a large
dairy cooperative farm of the highlands of the occident of Mexico.
All cows presented a history of repeat breeding, and further more,
during palpation the presence of an ovaryan cyst was detected.
Divided at random in three groups of 15 cows. Group one was
treated with 15 µg buserelin im on the oestrus day of insemination.
Group 2 was treated with naloxone, 5 mg im at 12 hour intervals for
three consecutive days, treatment commenced since one day before
insemination. Group 3 was used as a control injected with 5 ml im of
saline solution at 12 hour intervals for three consecutive days,
injections commenced since one day before estrual insemination.
Cows were inseminated twice (12 h apart) according to the AM-PM
rule and pregnancy was confirmed by rectal palpation between 12
and 18 weecks after the last insemination. Pregnancy rates in
buserelin treated repeat breeder cows was 56%, while pregancy rate
in naloxone treated cows was 89% and control cows showed a 20%
pregancy rate. There was a significant correlation betweein
progesterone levels and pregancy rate in all groups. It was concluded
that opioids participate significantly in expression of estrous
behaviour and ovulation in repeat breeder Holstein cows
Key words: buserelin, naloxone, dairy cows
376 The Incidence of Repeat Breeding and Subsequent
Reproductive Performance in High-producing Dairy Cows
T. Nakao 1 , Y. Mohammad 1 , K. Koike 1 , C. Yoshida 2 , K. Yamada 3
1 Yamaguchi University, Department of Veterinary Medicine,
Yamaguchi, Japan
2 Niigata University, Facuty of Agriculture, Niigata, Japan
3 Nemoro NOSAI, Shibetsu Large Animal Clinic, Shibetsu, Japan
Declining fertility in lactating dairy cows has recently been reported
worldwide. The underlining causes of the subfertility have been
known to be the increase in milk yield and resultant negative energy
balance during an early lactation period. It is assumed that, as the
consequence of reduced fertility, the incidence of repeat breeding
has increased in today’s high producing cows. This paper aims to
show the incidence of repeat breeding in eight commercial dairy
herds across Japan, which were monitored for ovarian cyclicity and
reproductive performance by twice weekly milk progesterone assayd
and regular herd visits during a period from April 2004 to July 2005.
Of a total of 274 cows, 15.2% cows had not conceived after the third
AI or the subsequent AI without showing clinical reproductive
abnormalities (RB cows). The incidence of repeat breeding among
eight different herds ranged between 6.8 and 20.3%. Two hundred
and one cows conceived after first, second, or third AI (fertile cows).
The RB cows, in comparison with the fertile cows, showed a lower
pregnancy rate within 210 d after calving (38.9% vs.
94.5%)(P