Oral and Poster Abstracts

inseminator were tested in regression models and terms were
retained in the model if influential. Five days after treatment, the
proportion of cattle with more than one CL was 72% and 7%
(P11,000 kg of
milk/cow/year, and use automatic pedometry systems (recording
cow steps) for heat detection. A controlled randomized trial was
conducted from July 2006 until December 2007. Anoestrus cows
were treated according to each farm protocols. Total of 1450 cows of
all lactations after artificial insemination (AI) were randomly
allocated into tow nearly equal groups: US and RP. The RP cows
were submitted to PD by fetal membrane slip technique between
days 42-48 after AI, and the US cows were PD between days 26-32
after AI and reexamined by RP between days 42-48 after AI. Cows
which were detected on heat between AI and the set PD time in each
group were reinseminated. Results: Days open were 122 and 123 in
herd B and 115 and 115 in herd A, in the US and in the RP groups
respectively, with no statistically significant differences. The overall
conception rate from first insemination was 42.7 for herd A and 44.3
for herd B. The groups did not differ significantly in following
reproductive risk factors: endometritis, ketosis, negative energy
balance and summer calving. Most of the active open cows were
detected on heat and reinseminated before reaching the first PD. The
EED rate in the US group, measured by the drop of pregnancy rate
between the day 26-32 and the day 42-48 PD, was 5.9% and 6.1% in
farm A and B respectively.
Conclusion: There was no difference in days open and therefore no
reproductive benefit in early ultrasound pregnancy diagnosis in these
cows herds. As part of the open cows were detected on heat before the
US PD and the true anestrous cows take longer to conceive, the
potential 16 days advantage in days open for the US cows was reduced
to an insignificant difference.
303 Resynchronization and Early Pregnancy Detection may
Enhance Reproductive Performance of Lactating Dairy Cows
A. Niasari-Naslaji 1 , M. Bolourchi 1 , S. Shabani 2 , D. Nikjou 1 ,
A. Moghiseh 1
1 Faculty of Veterinary Medicine, University of Tehran, Department
of Clinical Sciences, Tehran, Iran
2 Bosatn Agro-Inductrial Co, Hashtgerd, Iran
Early identification of non-pregnant cows using ultrasonography and
their resynchronization using GnRH-PG protocol has been applied
recently as a managerial tool to enhance reproductive performance
of lactating dairy cows. During 8 months study in a well-managed
dairy farm, 141 healthy lactating dairy cows, without any particular
reproductive problems, >45 days open, were selected, randomly
assigned into two group at the time of AI and monitored until they
became pregnant. Experimental cows were inseminated 12 hrs after
observing standing estrus using frozen semen. Cows in control group
(n=67) did not receive any treatment. On Day 20-25 after AI, cows
in treatment group were scanned ultrasonically (Sonovet 2000, 5-9
184 XXV. Jubilee World Buiatrics Congress 2008
MHz linear rectal transducer) for the characterization of follicle and
CL on the ovary and given an ovulating dose of GnRH (15 µg
Luliberin-A, Vetaroline, Aburaraihan, Iran). On Day 27-32 after AI,
pregnancy was diagnosed using ultrasonography and non-pregnant
cows received prostaglandin F2 analogue (PG, 500 µg cloprostenol).
Cows that returned to estrus were re-inseminated 12 hrs after
observing standing estrus. Pregnancy was rechecked on Day 50-60
days after AI by rectal examination. Data with discrete nature were
analyzed using Genmod procedure including logit in the model and
data with continuous nature were subjected to GLM procedure
following appropriate transformation. On Day 20-25 after AI,
ovarian follicle (16.8±0.42; 10-30 mm) and CL (27.8±0.45; 15-35
mm) were recorded for resynchronized cows. The number of days
open, the days from AI, followed by resynchronization, to pregnancy
and total services per conception were significantly higher (P