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Abstract
It has been concluded that uterine rather than ovarian factors appear to be more important in differing pregnancy rates in recipient cows. Forty three Holstein-Friesian high yielding recipient cows were used to investigate the possible predisposing factors for embryonic mortality. The animals were bred by embryo transfer (ET) at the 7th day after estrus. Pregnancy diagnosis was carried out by ultrasonography on a weekly basis in order to detect the exteofof energy balance including ~-hydroxybutyric acid (BHBA), non estrified fatty acids (NEFAs), Total cholesterol (T-chol), glucose and blood urea nitrogen (BUN) on subsequent embryonic mortality. During estrus, BHBA was higher (P<O.OI) in PREG group (651.7 ± 115.3 Jlmol/l) than that ofED group (303.1 ± 50.6 Jlmol/l). NEFAs was higher (P<0.05) in ED group during week 7 pp (355 ± 157.5 JlEq/l) and estrus (298.7±158.2) than that of PREG group (188.2 ± 69.3 JlEq/1 and 155.8 ± 90.0 JlEq/l, respectively). BUN was higher (P < 0.05) in PREG group (14.8 ± 5.1 mg/dl and 14.5 ± 4.3 mg/dl) than that ofED group (10.3 ± 2.5 mg/dl and 9.6 ± 4.5 mg/dl) during week 7 and estrus, respectively.
In experiment Ill: The climatic factors, milk production and estrus intensity were assessed and its relation to subsequent embryonic mortality. Maximum temperature humidity index (THI) during estrus, ET day, from estrus to ET or from ET to d 20 after conception was not associated with subsequent embryonic mortality. Estrus intensity as detected by pedometers
tended to be higher in PREG than ED group (447 +164.8 vs 354.6 +106.8 steps/hour; P= 0.3). Moreover, estrus length in hours tended to be longer (P < 0.1) in PREG group than in ED group (11.9 +2.8 vs 9.8 +2.2 hours).
In experiment IV: ISG 15 is induced by conceptus-derived interferon-’t (IFN-’t) in the endometrium on days 15-45 of pregnancy. The goal was to detect ISG 15 level in peripheral blood after ET and the
possibility of using such technique to identify early embryonic death (EED). ISG 15 and P 4 were detected in blood collected on days 0 (estrus), 14, 16, 18, 20, 22 and 24 after estrus by real-time PCR and TR-FIA respectively. It was found that 42% were pregnant (19/43), 41.9% (18/43) were not pregnant and 13.9 (6/43) were experienced EED between days 18 and 24. During days 18 and 20, ISG 15 mRNA was higher (P < 0.01) in pregnant and EED animals than that of bred non pregnant animals and then decreased during d 22 (P < 0.05) in EED animals. At d 20, P4 concentration was significantly (P < 0.001) lower in bred non pregnant when compared to both pregnant and EED animals. At d 22, P 4 concentration in pregnant animals was higher than that of bred non pregnant animals (P < 0.001) and EED animals (P<0.05)
In experiment V:. Five Jersy female animals were used to evaluate whether single intrauterine infusion of bovine IFN-’t could induce pseudo-pregnant state in non pregnant cattle and lengthen interestrus intervals and CL lifespan. In addition, to detect the first appearance and disappearance of the adverse side effects of IFN tau administration. Each cow was administered 2 mg of Interferon tau or blacebo (BSA 1%) in the most anterior third of the uterine horn ipsilateral to the ovary containing CL during the 13th day after estrus (estrus=O). The interestrus interval was longer (P < 0.01) in IFN treated group (23.0 ± 1.5 days) than that of placebo treated one (21.3 ± 0.8 days). Based on P4 concentration, CL life span prolonged (P < 0.01) after IFN-t injection (20.5 ± 2.2 days) when compared to placebo (18.1 ± 1.9 days).
IFN-’t-treated animals suffered from hyperthermia 3 hours after injection that returned to normal 24 hours after treatment. There was a prominent leucopenia and lymphopenia 12 hours after treatment in IFN-’t-treated group.
It is concluded that recombinant IFN-’t had a luteotropic effect through inhibition of PGF 2a release and may take part in alteration of immune function during maternal recognition of pregnancy. Detection of ISG 15 during early pregnancy could be used as a diagnostic tool of early embryonic mortality. Presence of FlU during week 3 or 4 pp might be a good indicator of subsequent low embryonic mortality. Moreover, presence of vaginal purulent or mucupurulent discharge during week 4 pp might be associated with subsequent embryonic mortality. Climatic factors including temperature and humidity, milk production may not have an adverse effect on embryo survival after transferring of good quality embryos. On the other hand, estrus intensity or duration may take part in subsequent embryo survival.