Bovine Prenatal Development: A Comparative Study of Ultrasonography and Radiography Techniques

Mowa, Chishimba Nathan (1994) Bovine Prenatal Development: A Comparative Study of Ultrasonography and Radiography Techniques. MVM(R) thesis, University of Glasgow.

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This study was undertaken with the aim of assessing the use of high frequency transducer (7.5 MHz) and a quality ultrasound scanner in the study of in-uterine bovine fetal development i.e. bovine fetal age determination and the ultrasonographic anatomy of the gross tissues and organs of the developing bovine fetus, particularly the stomach compartments, between gestational age 45-90 days. Additionally, ultrasonography was compared to radiography and bone staining techniques, in the study of fetal osteogenesis. The simple regression, polynomial and logarithmic mathematical models were used to examine and analyse in depth, the growth rate and patterns of crown rump length, biparietal diameter and trunk diameter. Each model was tested for fitness of the raw data, precision to predict age and ability to describe the various characteristics of the growth curve of fetal parameters. On average, crown rump length had the fastest growth rate and the least variance, while, trunk diameter had the slowest growth rate and the highest variance of the three fetal parameters analysed. The best mathematical model, out of the three, for crown rump length, in terms of fitness of the raw data and precision to determine fetal age, was the logarithmic model. The linear model was good at giving an overall impression of the average growth rate and steepness of the growth curve. The model with the best fit of the raw data of biparietal diameter and the most precise in determining fetal age was the polynomial model. No major difference in the growth rate and size was noted between the width and depth of the trunk diameter and between sizes of trunk diameter taken at the level of the umbilicus and the stomach This study did not find any major difference of statistical significance between growth curves of embryo transfer fetuses and normal fetuses. The linear model was the simplest of the three models assessed: deriving the age prediction equation and identifying the features of growth that the coefficients represented was easier than with the other two models. It could also be used to ascertain the average growth rate during a given period. However, it could only be used in linear growth curves, usually present in early gestation and not non-linear characteristics seen in a typical growth pattern of later pregnancy. The polynomial model had three coefficients, and hence is more complex to interpret and derive age prediction equations, compared to the other two models. It is, therefore, not, in most cases, a good model to use for the purpose of estimating age. However, it was very good at defining and describing the extent and direction of both linear and curvature features of the growth curves. It did not, however, specify the points at which these curvings begin and end on the growth curve. The two coefficients of logarithmic model are relatively easy to interpret and to derive age prediction equation. It was the most ideal for the purpose of estimating age using fetal dimensions which have typical curvilinear or sigmoid growth curves, because it was able to transform nonlinear raw data into linear and has uniform variations and hence, the least coefficient of variation . No difference, in precision, in determining age of in-uterine bovine fetus between transducers with higher frequency and (7.5 MHz) and those of lower frequencies was found (3.5 and 5.0 MHz.), based on early bovine fetal development. The improvement of precision in fetal aging and a clearer understanding of growth patterns may depend, among other things, on the use of an appropriate age prediction model, at a given age and not so much on the use of transducers of higher frequencies. Sonographic images of almost all the major fetal structures, like the brain, orbit, maxilla, mandible, heart, blood vessels, stomach, hind and forelimbs, were identified by Day 45 of gestation. Sonographic images of the stomach could be identified by Day 39 of gestation, although it was not possible to recognise the differentiation of the stomach compartments until after Day 53 of gestation. The first compartment of the stomach identifiable sonographically was the reticulo-rumen. Differentiation of the rumen into its various sacs became apparent by Day 60 of gestation. Differentiation of the omasum first appeared as a round hyperechogenic structure by Day 53 of pregnancy. The laminae omasi appeared one week later. Other structures of the omasum identified included the esophageal groove and omasi sulci by Day 70 of gestation. The most difficult stomach compartment to identify was the abomasum, because of the close resemblance of its images and its proximity to the intestines. The reticulum was imaged by Day 76 of pregnancy and structures scanned immediate to it were; the liver and diaphragm, cranially, the vestibule of the rumen, caudally and the omasum on the right. The sensitivity of ultrasonography and radiography techniques in detecting the earliest time and chronological order of appearance of the loci of ossification were found to be the same.

Item Type: Thesis (MVM(R))
Qualification Level: Masters
Additional Information: Adviser: John S Boyd
Keywords: Veterinary science, Animal sciences, Developmental biology, Morphology
Date of Award: 1994
Depositing User: Enlighten Team
Unique ID: glathesis:1994-76309
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 Nov 2019 15:47
Last Modified: 19 Nov 2019 15:47

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