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Biomedical subjects

D N Logue

Publications and source records attributed to D N Logue.

12 recordsLinked to original sources
PubMed1992

Evidence for the action of bovine follicular fluid factor(s) other than inhibin in suppressing follicular development and delaying oestrus in heifers.

The aim of this study was to investigate the importance of inhibin in the delay in return to oestrus in heifers induced by steroid-stripped bovine follicular fluid (bFF). Oestrous activity was synchronized in 18 Hereford x Friesian heifers with two injections of prostaglandin (PG) 12 days apart. At the time of the second PG injection (time 0), the animals were assigned at random to one of three experimental groups and received i.v. injections of 20 ml saline (controls, n = 6), whole bFF (FF group, n = 6) or bFF in which the bioactive inhibin content had been reduced by > 95% by immunoaffinity chromatography (-INH group, n = 6; inhibin content approximately 0.8 ml whole bFF) every 8 h for 2 days. In a dose-response study, 2.5 ml whole bFF was insufficient to delay oestrus consistently following a similar synchronization regimen. Blood samples were taken every 8 h, initially before each injection and then subsequently for a further 9 days for hormone analysis. Animals were observed every 8 h throughout the experiment for signs of behavioural oestrus. The ovaries of all animals were examined using real-time ultrasonography about 30 h after the second PG injection. Treatment failed to suppress peripheral follicle-stimulating hormone (FSH) concentrations, although a significant increase was observed in both treatment groups after cessation of injections. Progesterone concentrations fell immediately after the second PG injection in all animals and remained below minimum detectable concentrations in all treated animals for the remainder of the experiment. In control animals, progesterone rose above minimum detectable concentrations by day 6 and continued to rise until the end of the experiment. Analysis of samples taken from treated animals several days after observed oestrus revealed that all had apparently ovulated. Mean daily luteinizing hormone (LH) concentrations did not differ between treatment groups before ovulation, but after ovulation, mean daily LH was significantly reduced in control animals as progesterone concentrations rose. Follicular development, as assessed by the mean antral diameter of the largest follicle on a pair of ovaries at ultrasound examination, was significantly suppressed in treated animals compared with controls (P < 0.01) and there was no significant difference (P = 0.397) between the two treatment groups. Control animals displayed oestrus 68 h (+/- 8 SEM) after the second PG injection, but oestrus was delayed in treated animals to 186h +/- 5 (FF group) and 191 h +/- 6 (-INH group).

Analysis of Variance↗
PubMed1991

A comparison of two techniques for the synchronisation of oestrus in dairy heifers.

Seventy-four heifers in four separate breeding groups were allocated into two treatment groups for oestrus synchronisation. Group 1 was given a combination of an initial injection of norgestomet and oestradiol valerate together with a norgestomet ear implant left in place for nine days. Group 2 was given two injections of the synthetic prostaglandin luprostiol 10 days apart. The animals in group 1 were artificially inseminated once 48 hours after the removal of the implant and those in group 2 were inseminated once 72 hours after the second injection of luprostiol. Subsequently any returns were rebred by either AI or natural service. There was no significant difference between the numbers of animals in the two treatment groups which were diagnosed pregnant 33 to 35 days after insemination, although the implant treatment gave a higher overall proportion of pregnancies (70 per cent, 51 per cent). It also gave significantly smaller numbers of 'open' days over the whole of the breeding period. A study of individual animals by progesterone assay and investigation of ovarian structures by real-time ultrasound showed that some of them had unusual progesterone profiles but nevertheless became pregnant. It would appear that a corpus luteum may be responsive to prostaglandins even though it is secreting only a low level of progesterone.

Animals↗
PubMed1979

Hormonal and histological studies in a 61XXY bull.

A Friesian bull with bilateral testicular hypoplasia was diagnosed as having a pure 61XXY karyotype. The bull displayed normal sexual behaviour but was azoospermic. At 17 months, the animal's peripheral plasma androgen levels appeared to be lower than normal, and one testicle removed one month later showed small seminiferous tubules totally lacking in germ cells. The Leydig cell volume of this testis was well within the normal range but the tubule length was rather short. At 33 months of age an increase in peripheral plasma androgen levels was noted. In the remaining testis there had been both a considerable rise in Leydig cell volume and a fall in tubule length. These findings may be explained by the interaction of three factors; the effects of the abnormal karyotype, the increased maturity of the animal at 33 months and the reaction of the remaining testis to unilateral castration.

Androgens↗
PubMed1979

Tubule length and Leydig cell volume in the normal bull testis.

Data are presented on the size, Leydig cell content and seminiferous tubule dimensions of the normal bull testis. A method of estimating total tubule length, requiring only the measurement of testis volume and the number of tubule cross-sections in a unit area is described, and its applicability to the bull established. The average bull testis contains about 5.2 km of tubules.

Animals↗
PubMed1978

Meiosis and spermatogenesis in bulls heterozygous for a presumptive 1/29 Robertsonian translocation.

Bulls heterozygous for the 1/29 Robertsonian translocation showed normal mating behaviour, semen quality and spermatogenesis. The karyotypes of 90 offspring of one heterozygous bull were consistent with a normal 1:1 segregation of the translocation. There was no difference in overall chiasma frequency at diakinesis between heterozygous and normal bulls, and while a trivalent was noted at diakinesis the chiasma position within the No. 1 arm of the trivalent did not appear to be altered when compared with that found in the normal No. 1 bivalent. An increased frequency of aneuploid secondary spermatocytes at the second meiotic division (M II) was found in the heterozygous bulls, the rate of non-disjuction based on the proportion of hypermodal cells being raised from 2.8% in the normal to 6.4% in the heterozygous animals.

Animals↗
PubMed1978

Chromosome banding studies in cattle.

A recent advance in the field of cytogenetics has been the ability to stain differentially specific areas or bands on the fixed chromosome. In terms of clinical and paraclinical work C- and G-bands have been of most value to date in allowing precise identification of chromosome homologues even in species such as cattle, where the vast majority of chromosomes are of a similar morphology. These methods have allowed at the gross level of the chromosome the precise identification of a number of Robertsonian translocations and certain aneuploids. In this study 1/29 Robertsonian translocations were found in three separate breeds. Also a 14/20 and a 6/16 Robertsonian translocation were identified as was a 61XXY sterile bull. In the future these techniques will allow the identification of as yet unidentified anomalies in cattle such as reciprocal translocations and paracentric inversions. Since many anomalies have been correlated with such clinical problems as early embryonic death, abortion, congenital anomalies and reduced reproductive efficiency in the mammalia, it is important to use cytogenetics as an additional laboratory aid in such investigations.

Aneuploidy↗
PubMed1978

A 14/20 Robertsonian translocation in Swiss Simmental cattle.

A chromosomal abnormality identified as a 14/20 Robertsonian translocation by measurement and banding studies has been found randomly in several Swiss Simmental cattle. These cases have all been traced back to one ancestral bull. The testicular function of three unselected male offspring, two heterozygotes and one normal was studied. All possessed apparently normal spermatogenesis. In a meiotic study no alteration of overall chiasma counts were found at diakinesis in the heterozygous bulls compared with the normal, while the presence of a trivalent confirmed the diagnosis of a Robertsonian translocation. Also in the heterozygotes a small number of secondary spermatocytes were identified but they were too few to draw any firm conclusions regarding alterations in non disjunction rate.

Animals↗
PubMed1977

Arthrogryposis-palatoschisis and a 1/29 translocation in a Charolais herd.

The congenital condition of arthrogryposis palatoschisis was found in two closely related Charolais calves and has subsequently been found in a number of other related animals. It would appear from this and earlier reports that the condition is inherited, possibly as an autosomal recessive. A 1/29 Robertsonian translocation was also found in one of the calves and this was inherited from its dam. It is considered that the two conditions are not directly related.

Animals↗