Ultrasonographic Studies on Early Bovine Pregnancy Diagnosis and Foetal Sexing

Diniz de Moura, Roseana Tereza (1993) Ultrasonographic Studies on Early Bovine Pregnancy Diagnosis and Foetal Sexing. Master of Veterinary Medicine thesis, University of Glasgow.

Abstract

This thesis is an attempt to further the knowledge of the use of real time B-mode ultra-sound scanning in the management of reproductive events in cattle. There have been a number of reports of the use of ultrasonography in an attempt to identify early bovine pregnancy. However, this has resulted in a variety of results and statements about the efficiency of the technique, and the earliest day of pregnancy on which an accurate diagnosis can be achieved. This has been due to the use of a range of transducers of different frequency and a diversity of criteria quoted for establishing a positive diagnosis. The first section of this thesis is designed to establish a technique with rigid criteria for pregnancy diagnosis, using a high frequency 7.5 MHz transducer and a scanner of good quality. The protocol was chosen so that adult cows were examined ultrasonographically for pregnancy three times, at each of three separate time windows, these being Days 16 to 20, Days 21 to 27 and Days 28 to 34 after breeding. For each of these time spans, criteria were evolved for the ultrasonographic appearance of the ovary, the uterine horn and the conceptus. In all cases, it was essential that the ovary exhibited an active corpus luteum of good echogenicity. The uterus was required to have a distended lumen with an anechoic centre and a smooth endometrial lining in all three time windows, but the degree of its distension varied according to the stage of the pregnancy. In the earliest period of pregnancy diagnosis, distension of the uterine horn was considered sufficient evidence, coupled with the necessary appearance of the corpus luteum and uterine lining, to give a positive identification. However the presence of an early embryo enhanced the diagnosis. In the second time windo it was necessary to establish the presence of an echogenic embryo with an heart beat as well as the necessary criteria for the corpus luteum and uterine lining. These criteria were also applied to the third time window, but here embryonic anatomical detail was available, and imaging of the placental membranes was obtained. The second and third group of scans proved to be 100% accurate when these criteria were rigidly applied. In the first phase errors were recorded, but they were explained by the occurrence of embryonic loss, which is discussed in the thesis. The second section of the thesis is an evaluation of the efficacy of the more recently described techniques for foetal sexing, which have given a variety of parameters and dates for producing a diagnosis. A group of adult pregnant cows were examined during the period 48 to 62 days of pregnancy. Using embryological rationale and anatomical knowledge of foetal anatomy, it was possible to produce a high degree of accuracy for sex determination during the 51 to 54 day period. There was a distinct learning curve associated with the success and the pitfalls of the thechnique, and the possible sources of error are discussed in the thesis, which is the first in this area to attempt to elaborate on this technique using a high frequency transducer. The findings of the work show that it is possible to use a high frequency transducer, with real time ultrasonography, to evaluate pregnancy with 100% accuracy from 20 days of gestation and within 88% accuracy from 16 days, as long as rigid criteria are adhered to. Foetal sexing is highly dependent on the skill and experience of the operator, which can achieve accurate results from 51 to 54 days of gestation. The technique has potential for wide application in the field of herd management.

• Item Type: Thesis (Master of Veterinary Medicine)
• Qualification Level: Masters
• Additional Information: Adviser: John S Boyd
• Keywords: Veterinary science
• Date of Award: 1993
• Depositing User: Enlighten Team
• Unique ID: glathesis:1993-76308
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 19 Dec 2019 09:15
• Last Modified: 19 Dec 2019 09:15
• URI: https://theses.gla.ac.uk/id/eprint/76308