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Biomedical subjects

R N Kay

Publications and source records attributed to R N Kay.

At least 19 recordsLinked to original sources
PubMed1984

Endocrine control of antler growth in red deer stags.

Observations of body weight, testis size, antler status, plasma testosterone and prolactin were made on 12 red deer stags during their first 2 years of life. Six of the stags were fed to appetite throughout the study (Group A) and 6 were fed a 70% restricted diet during each winter (Group B). In addition 6 of the stags , 3 from each group, were studied in more detail; LH and testosterone were measured either after a single injection of LH-RH or in samples taken at frequent intervals over a period of 8 or 24 h. During the study the stags became sexually mature, developed first their pedicles and then antlers and showed at least one complete cycle of casting and regrowth of the antlers . The stags in Group A developed their testes and pedicles about 2 months earlier than did those in Group B. Pedicle initiation was associated with increasing plasma testosterone levels in response to changes in LH secretion, and antler development occurred when testosterone levels were low or decreasing. Cleaning of the velvet was associated with high levels of plasma testosterone. Antler casting occurred when plasma testosterone concentrations were low or undetectable and prolactin levels were high or increasing. The relationship between LH and testosterone varied during the study; in spring when the testes and antlers were growing, relatively high levels of LH were associated with only small peaks of testosterone, yet in summer, when antler growth was complete and the antlers were clean of velvet, low LH concentrations were associated with large peaks of testosterone.

Animals↗
PubMed1984

Influence of winter feed restriction and summer compensation on skeletal development in red deer stags (Cervus elaphus).

The influence of two planes of nutrition (unrestricted and 70 per cent restricted during the winter) on skeletal development as illustrated by the metacarpus was studied in 12 red deer stag calves. At approximately three-monthly intervals from January 1978 when the stags were seven months old, until August 1979 when the stags were 26 months old, radiographs of the right metacarpus were taken. From the resultant radiographs, diaphyseal length, diaphyseal breadth, breadth of mineralised bone, cortical bone index and area of mineralised bone were measured. Growth in length was complete by August 1978. There were no differences in length between the unrestricted and restricted stags at that time. Differences in breadth, area and cortical bone index were maintained throughout the study although differences in area of mineralised bone were the only measure significantly different throughout the study. It is considered that the major influence of plane of nutrition on this index of skeletal development in deer is on breadth and thickness of cortical bone, resulting in a weaker bone of the same length in the winter restricted stags.

Animals↗
PubMed1983

Rumen function and physiology.

The regulation of rumen fermentation and motility are described to provide a framework within which the opportunities and problems of intensified ruminant nutrition can be considered. The ruminant animal maintains favourable conditions for microbial growth in its rumen and in turn is nourished by the products of fermentation. The fermenting food needs to be masticated, fluidised, buffered, mixed, kept at an even temperature and propelled onward down the gut to be absorbed. Rumen movements are appropriately controlled by a combination of central and local mechanisms.

Animals↗
PubMed1983

Outbreaks of Salmonella newport infection in dairy herds and their relationship to management and contamination of the environment.

Two outbreaks of Salmonella newport infection in dairy herds are described which were characterised by haemorrhagic enteritis. The history of the outbreaks, the extent of the losses, clinical and laboratory findings and treatment are described. The first herd consisted of 193 cattle, of which seven died, three aborted and another 84 required treatment. Salmonellosis persisted over 14 months throughout the summer on a paddock grazing system and continued during the following winter when the herd was loose housed. The relationship of the commencement of clinical disease to dietary changes and to the time of calving is described, as are the problems in controlling the disease. The second herd consisted of 98 milking cows and a few beef animals. One cow died and two aborted; altogether 18 were clinically affected. The epidemiology of the disease and the geographical relationship between the two farms is described. Extensive contamination of streams occurred and one cow died on a neighbouring third farm. In contact humans were found to be excreting the organism. The public health significance of the outbreak is discussed because bulk milk samples were contaminated with salmonellae for 10 months and local streams were polluted with human sewage.

Abortion, Veterinary↗
PubMed1983

Winter food restriction and summer compensation in red deer stags (Cervus elaphus).

Twelve red deer stags (Cervus elaphus) penned individually from weaning were fed on a concentrate diet. Six stags received the diet to appetite throughout the study, and the other six were restricted to 70% of the intake of the first group during winter and then fed to appetite during summer. The winter-restricted stags showed remarkable compensatory growth during summer. Compared with the unrestricted stags they showed greater food intake, greater daily live-weight gain and increased food conversion efficiency. Nonetheless, they failed to compensate fully for the previous undernutrition. The hind-foot of the restricted stags failed to grow as long as that of the unrestricted stags. Poor winter nutrition, particularly during the first year of life, and subsequent failure to compensate during the short periods of summer plenty, provides an explanation for the small mature size of wild stags in Scotland. Although the winter-restricted stags were less fat both grossly and relative to body-weight than the unrestricted stags, both groups showed the same relationship of level of fatness to empty-body-weight. In both the groups of stags, extensive fat deposition began once they had reached about half their expected mature weight, a much later stage of development and age than in sheep and cattle. The annual cycle of growth and appetite is considered to form part of a complex adaptive system to enhance survival in a harsh seasonal environment followed by a mild seasonal environment. On Scottish hills deer reach a size appropriate to their environment rather than their genetic potential size.

Animal Nutritional Physiological Phenomena↗
PubMed1981

Metabolism of the nucleic acids of rumen bacteria by preruminant and ruminant lambs.

1. A rumen bacterial culture containing specifically labelled nucleic acids was prepared using [8-14C]adenine. 2. The labelled preparation was given in a liquid diet to two preruminant lambs and via a rumen tube to two ruminant lambs. The radioactivity excreted in exhaled gases, faeces and urine and that incorporated into tissues was determined. 3. The preruminant lambs absorbed 58.3% of the total radioactivity measured after 24 h and the ruminant lambs 66.6% of the total activity measured after 48 h. 4. Of the total radioactivity absorbed the preruminant lambs exhaled 38%, excreted 34% in urine and retained 29% in tissues. The corresponding values for the ruminant lambs were 12, 41 and 47% respectively. 5. There was a close relationship between total nucleic acid content and radioactivity per g of tissues of both preruminant and ruminant lambs. 6. Of the radioactivity in the urine, the ruminant and one preruminant lamb excreted most in the fraction containing allantoin, while the other lamb excreted most activity in the uric acid fraction. 7. The salvaging of the breakdown products of bacterial nucleic acids to make tissue nucleic acids appears to be an important synthesis in preruminant and ruminant lambs and of the likely precursors the purine base may be more important than the nucleoside.

Animals↗
PubMed1979

Effects of season on the secretion of LH and testosterone in intact and castrated red deer stags (Cervus elaphus).

At 2--4 monthly intervals during the year blood samples were collected every 15 min for 6 h from 2 intact and 3 castrated red deer stags to study the relationship between season and the secretion of LH and testosterone. In the intact stags plasma LH and testosterone concentrations changed during the year; the LH levels were maximal in August during the phase of testicular redevelopment, while the testosterone levels were maximal from September to November coinciding with the time of peak testicular activity and the mating season. The castrated stags had higher plasma levels of LH than the intact stags at all times of the year, and there was no clear seasonal cycle in LH levels in these animals.

Animals↗
PubMed1977

Variation in the weight, specific gravity and composition of the antlers of red deer (Cervus elaphus L.).

1. Antlers were removed in September from 2-4 year old red deer (Cervus elaphus L.). Both well-fed penned stags and less well-nourished grazing stags were studied. 2. For deer of the same age, both log antler weight and log antler specific gravity were related to body-weight in September and to body-weight gain between March and September. The antlers of 3- and 4-year-old stags were heavier and tended to be denser relative to body-weight and body-weight gain than those of 2-year-old stags. 3. For grazing stags of a given age, antler weight and specific gravity, and body-weight and body-weight gain, were progressively less in the three successive years of the study. This appeared to reflect increasing stocking rate over this period. 4. The composition of the antlers did not vary significantly between penned and grazing stags or with age. However the concentrations of ash, phosphorus and magnesium in dry matter showed significant positive correlations with specific gravity, that of zinc a significant negative correlation, while calcium, copper and manganese showed no significant correlation. 5. The antlers evidently provide a useful index of the changes in body-weight of the stags.

Animal Nutritional Physiological Phenomena↗