Exencephaly in chicken‐pheasant hybrids

1. The incidence of exencephaly was investigated in chicken‐pheasant hybrids.

2. With the pheasant as sire, fertility was 7.lb6%, but with the fowl it was 19.lb5%; hatchability of fertile eggs, however, was similar, 42% and 41% respectively.

3. Only one exencephalic hybrid was obtained when the sire was the pheasant but 70 were noted when the fowl was sire. The incidence of this malformation in hatched chicks was 12 times more in crosses with the fowl as sire than in the reverse cross.

4. The frequency of exencephaly was greater with Rhode Island Red, Barred Leghorn or White Leghorn roosters than with Columbian Rock roosters.     

An equine cryptorchid with testicular and ovarian tissues.

Cytogenetic and histological studies were carried out on an intersex horse which was diagnosed clinically as a cryptorchid. Surgery confirmed the horse to be a bilateral abdominal cryptorchid and histological examination revealed ovarian tissue associated with the left epididymis. Chromosome analysis of cultured cells from testicular tissue, ovarian tissue and skin revealed 64-XX and 64-XY make-up, the left gonad containing a greater preponderance of XX cells over XY cells. The external characteristics and behaviour of the horse were indistinguishable from that of a "routine" cryptorchid. Other cases of equine intersexes are reviewed and theories for the discrepancies between genetic, gonadal and phenotypic sex are discussed.     

A comparison of the adrenal cortical response to ACTH stimulation in Angora and non-Angora goats

The adrenal cortex is believed to be implicated in the high incidence of abortion in the Angora goat. Stimulation testing with adrenocorticotrophic hormone (ACTH) was used to assess the adrenal cortical function in 5 Angora does from herds with a history of abortion and 5 non-Angora does. An acute test involving a single intramuscular (i.m.) injection of 0.25 mg of synthetic ACTH was given during anoestrus, at mid-oestrus, on day 90 and on day 120 of gestation. Blood samples were collected from the jugular vein at 30 min intervals for 1 h before and 5 h after injection. Cortisol concentrations rose within 30 min and returned to baseline values within 3.5 h. Cortisol production was lower (p<0.01) in the pregnant state compared to the non-pregnant state in both groups. Production of cortisol was consistently lower (p<0.05) in the Angora does compared to the non-Angora does during anoestrus and pregnancy and marginally so at mid-oestrus. A chronic stimulation test involving once daily injections of 0.5 mg of a depot form of ACTH i.m. for 7 days commencing on day 90 of pregnancy was also conducted. Cortisol concentrations rose to reach a peak on the third day of treatment in both groups. The values then declined in the Angora does despite continued ACTH treatment, while those for the non-Angora does exhibited a second peak. During and following this treatment, two non-Angora does delivered live kids (day 95, day 120). Out of 7 Angora pregnancies, one Angora doe aborted two dead fetuses at day 116. No significant difference in the cortisol response in the acute test was detected between the animals that aborted and their respective cohorts, but the two non-Angora does that aborted had significantly lower cortisol concentrations during depot ACTH administration. Progesterone and oestradiol levels did not differ between Angora and non-Angora animals during pregnancy or on the test days. The results suggest that the steroidogenic response of the adrenal cortex to ACTH stimulation is significantly less in Angora does with a history of abortion than it is in non-Angora does and support the view that the Angora goat would make a more limited adrenal cortical response to a stressful occurrence during pregnancy.     

Genetic diseases of sheep and goats

Congenital malformations and inherited disorders constitute a substantial proportion of the afflictions seen in sheep and goats. Of these, malformations tend to be similar in both species, whereas the genetic diseases encountered to date, with the exception of a few, are different. Of the 28 genetic diseases of sheep and goats described in this review, 60% and 62.5%, respectively, are monogenic disorders. For a majority of the monogenic recessive disorders encountered in these species, the carrier state is not detectable at present, whereas in others, in which a biochemical lesion is known (dermatosparaxis, erythrocyte glutathione deficiency, globoid cell leukodystrophy and glycogen storage disease), the carrier state is detectable with the aid of enzyme and surface protein markers. The latter group and the dominant disorders (anury, cataract, glomerulonephritis, and lethal grey in sheep; gynecomastia and anotia-microtia complex in goats) are easy to eliminate through selective breeding. The polygenic disorders (entropion, epidermolysis bullosa, hereditary chondrodysplasia, and muscular dystrophy of sheep, and udder problems in goats) are more difficult to eradicate, because the mutant genes responsible for these traits generally do not declare themselves until inbreeding brings together a critical concentration to create a health crisis in some, whereas others, which are only short of a few of these mutant genes, might go totally unaffected and therefore undetected. Chromosome defects of the structural nature (translocations) seen in sheep and goats generally create meiotic disturbances, which in a majority of cases lead to subfertility, whereas sex chromosome aneuploids are generally sterile.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of extended photoperiod on the spermatogenic activity of chicken-pheasant hybrids

1. Males of chicken-pheasant hybrids and non-breeding pheasants were exposed to photoperiods of 10 or 20 h/d to test the effect of light on spermatogenic activity. 2. Testicular weights of hybrids and pheasants exposed to 10 h/d were similar and extending the photoperiod did not increase this in hybrids, although it caused a 48-fold increase, and complete recovery of spermatogenic activity, in pheasant. 3. Extending the photoperiod caused an increase in the number of primary spermatocytes and a corresponding decrease in the number of spermatogonia in hybrids, however, stages beyond primary spermatocytes were not present. This suggests that the stimulus of extending the photoperiod, while sufficient to induce meiosis in existing germ cells, is not enough to effect proliferative bursts or to overcome the meiotic arrest in the hybrids.     

Open canalicular system of platelets in porcine stress syndrome

A study was undertaken to test whether a previously reported alteration in platelet morphology could be of predictive value for the detection of stress-susceptibility in pigs. Platelets from 20 normal pigs, nine pigs classified as stress-susceptible on the basis of their response to halothane challenge, and 11 siblings of halothane reactors belonging to two different breeds were subjected to electron microscopic examination. A quantitative analysis of electron micrographs, based on the extent of dilatation of the open canalicular system in platelets and the percentage of affected platelets, revealed that halothane reactor pigs could be distinguished from normal animals on the basis of their open canalicular system score. The discrete nature of the score categories in siblings indicates that platelet alteration may be an inherent component of the porcine stress syndrome and suggests that some of the false negatives in the halothane test may be identified as stress-susceptible on this criterion. Further studies involving a larger number of halothane reactors and siblings are needed to ascertain the consistency of the open canalicular system features and eventually, to develop a simple test system based on platelet alterations for the detection of stress-susceptibility in pigs.     

Cytology of bovine foetal fluids.

Cell contents of foetal fluids obtained separately from amniotic and allantoic cavities of live cows by transvaginal amniocentesis and by aspiration from pregnant uteri immediately after slaughter were studied using Papanicolaou's staining procedure. The samples obtained belonged to cows which were between ten to 24 weeks of gestation. Cell scrapings from foetal and membranous surfaces normally in contact with the foetal fluids were also stained simultaneously with foetal fluid smears by Papanicolaou's method to determine the probable origin of the cells detected in the amniotic and allantoic cavities. The cell types were classified according to morphology and tinctorial patterns and their origin was deduced on the basis of similarity to cell scrapings from the surface layers of foetus and foetal cavities. The evaluation of foetal fluid cells revealed that a majority of cells are of foetal origin and that the cytological features of these cells may be useful in assessing the condition of the foetus.