Reproduction in Domestic Animals - Facultad de Ciencias Veterinarias

16 t h International Congress on Animal Reproduction
214 Poster Abstracts
and preoovulatory follicles number in the exposed group (p< 0.04)
were observed. Ambient air pollution seems to affect selectively the
ovarian follicles, decreasing the antral follicle number and not
affecting the pool of immature follicles (small and growing). These
results suggests that changes in follicle maturation could be one of the
mechanisms involved in reduced fertility in female mice exposed to
ambient levels of air pollution.
Poster 25 - Developments in Sustainable Animal
Production and Reproduction
P565
Reproductive efficiency of F1 Holstein x Zebu crossed
cows raised in pasture conditions of central part of Brazil
Ruas, JRM 1 *, Silva, MA 2 , Borges, AM 3 , Carvalho, BC 4 , Ferreira, IC 5 , Valente,
DB 5 , Menezes, GCC 5 , Matos, CRA 5
1Research Department, Minas Gerais Agricultural Research Corporation-
EPAMIG, Brazil; 2 Animal Science Department, Faculty of Veterinary
Medicine-UFMG, Brazil; 3 Veterinary Clinics and Surgery, Faculty of
Veterinary Medicine-UFMG, Brazil; 4 MG Agricultural Research Corporation-
EPAMIG, Brazil; 5 Faculty of Veterinary Medicine-UFMG, Brazil
During the last decade significant increase in milk production and
expressive reduction in reproductive efficiency of herds of specialized
cows in Brazil were observed. Intensive genetic selection for
maximizing milk production has resulted in metabolic and hormonal
modifications that negatively affected milk production. Today the
Brazilian’s great challenge of milk production systems is to search for
adapted genotypes that show high productive and reproductive
efficiency in pastures conditions, high profitability and preserve the
environment This research evaluated the reproductive efficiency of
243 F1 Holstein x Zebu crossed cows raised in pasture conditions of
the central part of Brazil in the Experimental Research Center of
EPAMIG (Minas Gerais Agricultural Research Corporation). The
cows during the summer season are maintained in pastures of
Brachiaria decumbens and Brachiaria brizantha and during the dry
season lactating cows are additionally fed corn silage and sugar cane.
Mechanic milking with cow’s calf presence and natural mating are
used in the herd. First mating average (24 months), cow average age
(33.6 months) and cow average weight at first calving (451.5kg) were
considered satisfactory since these cows were raised in pasture
conditions. Cow body weight increased up to fourth calving
suggesting these animals did not reach the adult body weight yet.
Milk production average of 2,773.1kg was very high in comparison to
national milk production average 1,350.0kg (Embrapa – CNPGL,
2006). Days open averages were, respectively, equals to 163.7, 96.0,
88.4 and 70.6 for first, second, third and fourth calving cows.
Productive efficiency can be evaluated by kilogram of milk / calving
interval ratio but days open that is a reproductive trait has an effective
effect on herd productive efficiency. The results suggest a great ability
of F1 Holstein x Zebu cows to adapt to pasture conditions and to show
high reproductive and productive efficiency in this production
systems. Factors related to animal behavior and to mechanic milking
adaptation should be considered in further studies.
Poster 26 - Trends in Research, Care and Teaching of
Reproduction
P566
Scanning Electron Microscopic (SEM) analyses of the
trophoblast of the term placenta of the Asian elephant
(Elephas maximus)
Loderstedt, S. 1 ; Hoffmann, A. 1 ; Eulenberger, K. 2 ; Flügger, J. 3 ; Seeger, J. 1
1Institute of Veterinary Anatomy, Department of Histology and Embryology,
Faculty of Veterinary Medicine, University of Leipzig, An den Tierkliniken 43,
04103 Leipzig; 2 Zoological Garden Leipzig GmbH, Pfaffendorfer Straße 29,
04105 Leipzig; 3 Zoo Hagenbeck Hamburg GmbH, Lokstedter Grenzstraße 2,
22509 Hamburg-Stellingen
Cognitions about structure and physiology of the Elephant placenta
are rare. The detailed characterization of the epithelial layer of the
chorion on different locations is poorly understood. Investigation with
ultrastructural procedures, scanning electron microscopic (SEM)
analyses are the first findings to investigate the morphological
features of the fetale membrane of the placenta in the Asian elephant
(Elephas maximus).
We used 3 term placentas (Zoological Garden Leipzig, Zoo
Hagenbeck Hamburg) and selected different sites of the placental
band and the extra placental Allantochorion.
The placental band has a sponge like surface, and consists of fetal
lamellae enclosing maternal blood vessels. The lamellae are covered
from the cytotrophoblast. The trophoblast cells show surface
modifications, like microvilli and mikroplicae. The fetal capillaries
are located directly underneath the cytotrophoblast and tend to invade
the epithelium. In some locations there are less than 2µm between
basallaminae of maternal and fetal intraepithelial capillaries. In none
of the investigated specimens the placental border has been reduced.
There is always a narrow trophoblastic cytoplasm band in between.
Microscopically the placental band can be divided in to two portions.
The apical, towards the uterus, and the basal, towards the fetus. The
apical layer is dispersed. Between the fetal, placental lamellae, blood
cells and amorphic material are located. The surface of the basal part
of the placental band is very dense. Fetal lamellae getting in direct
contact with maternal capillaries. Free blood cells, like in the apical
part can not be found. Maternal blood vessels are surrounded from
thickened basallaminae. There is a distinct difference between the
basallaminae of ematernal and fetal blood vesels. It must be proposed,
that the trophoblast cells are eroding the maternal basallaminae, and
the endothelial cells are producing even more collagenic material to
keep the laminae intact.
The chorionic surface is structured, and chorionic villi can be shown
entirely. The SEM analyses revealed a cobblestone-like architecture
of the epithelial cells, wich are covered with microvilli and
microplicae themselve. Surprisingly, the findings of intraepithelial
capillaries intend the trophoblast cells presume an nutrient exchange
also outside of the placental band with her gross functional
metabolism.
This study revealed some unknown and interesting features of the
epithelial layer of the chorion in the placenta of an Asian Elephant.
Perhaps, with a detailed knowledge of the morphology of the
epithelium we convey an better understanding of functional cohesions
of elephant placentation.
Acknowledgements
We are extremley gratful to Dr. M. Flügger of the Zoo Hagenbeck
Hamburg and also Prof. K. Eulenberger, Dr. J. Junhold and Mrs.
Bachmann of the Zoological Garden Leipzig for their continued
interest in this investigation and for their practical help in gathering
samples.