Structure of the Epidermis of Australian Merino Sheep Over a 12-Month Period

1985 ◽  
Vol 38 (1) ◽  
pp. 165 ◽  
Author(s):  
AG Britt ◽  
CL Cotton ◽  
BH Kellett ◽  
IH Pitman ◽  
JA Trask
Keyword(s):  
Stratum Corneum ◽  
Layer Thickness ◽  
Microscopic Examination ◽  
Seasonal Effects ◽  
Frozen Sections ◽  
Epidermal Structure ◽  
Merino Sheep ◽  
Light Microscopic Examination ◽  
Australian Merino

Light-microscopic examination of frozen sections of skin taken from the dorsal thoraco-Iumbar region of Australian Merino sheep in winter revealed that the thickness of the epidermis plus a sudanophilic layer was 24�9 !tm in the interfollicular region. The uncornified epidermis (10�9 !till) was separated from the sudanophilic layer (14�0 !tm) by a thin stratum corneum. It was concluded that the bulk of the sudanophilic layer was emulsified sebum in which was embedded a disorganized collection of desquamated cornified cells. Although large variances were observed in the thickness of the uncornified epidermis and of the sudanophilic layers between sheep and both within the between blocks of tissue obtained from individual sheep, there were no strong seasonal effects on either epidermal structure or layer thickness over a 12-month period. These results suggest that the Australian Merino differs from Finnish Landrace x Dorset Horn ewes, which are reported to possess, at least in winter, a thicker uncornified epidermis and a thicker stratum corneum that could be divided into two zones and was uniformly permeated by lipid.

scholarly journals Effects of the Sheep-Chewing Louse (Damalinia ovis) on the Epidermis of the Australian Merino

1986 ◽  
Vol 39 (2) ◽  
pp. 137 ◽  
Author(s):  
AG Britt ◽  
CL Cotton ◽  
IH Pitman ◽  
AN Sinclair
Keyword(s):  
Light Microscopy ◽  
Stratum Corneum ◽  
Lumbar Region ◽  
Louse Infestation ◽  
Chewing Louse ◽  
Merino Sheep ◽  
Positive Correlation ◽  
Stratum Spinosum ◽  
Australian Merino

Frozen longitudinal skin sections taken from the dorsal thoraco-lumbar region of adult Merino sheep that were infested with the sheep-chewing louse were examined by light microscopy. The epidermis of infested sheep exhibited acanthosis due to hyperplasia of the stratum spinosum, and orthokeratosis. The thicknesses of the uncornified epidermis, the stratum corneum, and the sudanophilic region were significantly greater (P < O� 005) than equivalent regions in louse-free Merinos and the results suggest that a positive correlation exists between the thickness of each region and the level of louse infestation. The results indicate that the variance in region thickness was greater in lousy than in louse-free sheep (P < 0'005).

DLC Coated Textile Vascular Prostheses Tested in Sheep

2013 ◽  
Vol 647 ◽  
pp. 20-24
Author(s):  
Miroslav Jelínek ◽  
Jiří Podlaha ◽  
Tomáš Kocourek
Keyword(s):  
Energy Density ◽  
Carotid Artery ◽  
Layer Thickness ◽  
Laser Energy ◽  
Diamond Like Carbon ◽  
Vascular Prostheses ◽  
Merino Sheep ◽  
Preliminary Results ◽  
20 Nm ◽  
Deposition Conditions

Textile vascular prostheses ARTECOR were coated by laser with amorphous diamond-like carbon layers (DLC) with thickness up to 200 nm. Layers were created in 0.25 Pa of Argon at laser energy density of 8 or 22 Jcm-2. Depending on the deposition conditions, DLC properties moved from soft „graphitic“ to more „diamond“ (53 % of sp3 bonds). Coated prostheses of various DLC thickness and sp3 content were implanted into carotid artery of Merino sheep. The prostheses were extirpated after 100 days (~180 days). From preliminary results follows that prostheses coated with DLC layer thickness of 20 nm and higher sp3 content showed the best results.

Studies in fleece-rot of sheep.

1953 ◽  
Vol 4 (4) ◽  
pp. 430 ◽  
Author(s):  
RH Hayman
Keyword(s):  
Microscopic Examination ◽  
Similar Condition ◽  
Unit Area ◽  
Skin Surface ◽  
Climatic Conditions ◽  
Field Station ◽  
Merino Sheep ◽  
Naturally Occurring ◽  
Sufficient Intensity ◽  
Experimentally Induced

Occasions of unduly heavy and prolonged rainfall during the period April 1946 – July 1951 resulted in the occurrence of fleece-rot in sheep of the Field Station flock in each of the six years. Data obtained from periodic examinations of the flock have been related to the nature of climatic conditions associated with outbreaks of the disease. They show that when rain occurs in falls of sufficient intensity and frequency to wet sheep to the skin for a period of a week or more, fleece-rot may be expected to develop in some of them. The longer the period for which the sheep are kept wet, the greater the number in a flock which will be affected. Fleece-rot was experimentally induced in four out of five Merino sheep known to be susceptible to the condition, whereas five animals known to be resistant were unaffected by the same treatment. Microscopic examination of skin sections taken from naturally occurring cases revealed the presence of a dermatitis. A similar condition was observed in skin sections from the animals in which fleece-rot was experimentally induced. Young sheep were found to be more susceptible than old. There was no association between degree of wrinkling and susceptibility or between 'grip' and susceptibility. When subjectively-appraised attributes of the fleece were related to the occurrence of fleece-rot, confusing results were obtained. However, when measured fleece data, obtained from a group of Merino sheep which had been under observation for four consecutive years, were considered, it was found that those for clean-scoured yield, wax and suint ratio, and density of fibre population per unit area of skin surface, were related to resistance or susceptibility. Nevertheless, a number of animals were found which were susceptible or resistant to the disease despite the nature of their fleece attributes. Differences in susceptibility were found between families of Merino sheep. These are associated with between-family differences for the fleece attributes found to be important in fleece-rot reaction.

scholarly journals A 500-year seasonally resolved δ<sup>18</sup>O and δ<sup>13</sup>C, layer thickness and calcite aspect record from a speleothem deposited in the Han-sur-Lesse cave, Belgium

2015 ◽  
Vol 11 (6) ◽  
pp. 789-802 ◽  
Author(s):  
M. Van Rampelbergh ◽  
S. Verheyden ◽  
M. Allan ◽  
Y. Quinif ◽  
H. Cheng ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Air Temperature ◽  
Short Interval ◽  
Winter Temperature ◽  
Seasonal Effects ◽  
Lower Amplitude ◽  
Temperature Reconstructions ◽  
Soil Activity ◽  
Instrumental Records ◽  
Δ18o And Δ13c

Abstract. Speleothem δ18O and δ13C signals enable climate reconstructions at high resolution. However, scarce decadal and seasonally resolved speleothem records are often difficult to interpret in terms of climate due to the multitude of factors that affect the proxy signals. In this paper, a fast-growing (up to 2 mm yr−1) seasonally laminated speleothem from the Han-sur-Lesse cave (Belgium) is analyzed for its δ18O and δ13C values, layer thickness and changes in calcite aspect. The studied record covers the period between AD 2001 and 1479 as indicated by layer counting and confirmed by 20 U / Th ages. The Proserpine proxies are seasonally biased and document drier (and colder) winters on multidecadal scales. Higher δ13C signals reflect increased prior calcite precipitation (PCP) and lower soil activity during drier (and colder) winters. Thinner layers and darker calcite relate to slower growth and exist during drier (and colder) winter periods. Exceptionally dry (and cold) winter periods occur from 1565 to 1610, at 1730, from 1770 to 1800, from 1810 to 1860, and from 1880 to 1895 and correspond to exceptionally cold periods in historical and instrumental records as well as European winter temperature reconstructions. More relative climate variations, during which the four measured proxies vary independently and display lower amplitude variations, occur between 1479 and 1565, between 1610 and 1730, and between 1730 and 1770. The winters during the first and last periods are interpreted as relatively wetter (and warmer) and correspond to warmer periods in historical data and in winter temperature reconstructions in Europe. The winters in the period between 1610 and 1730 are interpreted as relatively drier (and cooler) and correspond to generally colder conditions in Europe. Interpretation of the seasonal variations in δ18O and δ13C signals differs from that on a decadal and multidecadal scale. Seasonal δ18O variations reflect cave air temperature variations and suggest a 2.5 °C seasonality in cave air temperature during the two relatively wetter (and warmer) winter periods (1479–1565 and 1730–1770), which corresponds to the cave air temperature seasonality observed today. Between 1610 and 1730, the δ18O values suggest a 1.5 °C seasonality in cave air temperature, indicating colder summer temperatures during this drier (and cooler) interval. The δ13C seasonality is driven by PCP and suggests generally lower PCP seasonal effects between 1479 and 1810 compared to today. A short interval of increased PCP seasonality occurs between 1600 and 1660, and reflects increased PCP in summer due to decreased winter recharge.

Effects of inbreeding on four families of Peppin Merinos

1957 ◽  
Vol 8 (3) ◽  
pp. 299 ◽  
Author(s):  
JM Doney
Keyword(s):  
Fibre Diameter ◽  
Genetic Effect ◽  
Direct Consequence ◽  
Specific Gene ◽  
Single Strain ◽  
Merino Sheep ◽  
Fibre Number ◽  
Per Se ◽  
Fleece Weight ◽  
Australian Merino

The influence of inbreeding on several fleece and body characters in a strain of Australian Merino sheep is reported. The four families from which data were taken were derived from a single strain of Peppin Merinos. Inbreeding without selection has been carried on since the foundation of the families between 1939 and 1944. Inbreeding is responsible for a reduction in body size, fertility, greasy and clean fleece weight, and wrinkle score, but has relatively little influence on the fleece components (yield, staple length, fibre diameter, and density of fibre population). It follows that the reduction in fleece weight is a direct consequence of a decrease in total fibre number. Since the reduction in fibre number is likely to be a correlated effect of low pre-natal and early post-natal growth rates, it is suggested that the inbreeding has had no genetic effect on the several independent systems involved in adult wool production but has affected only those associated with fitness and vigour. The depression due to inbreeding therefore may not be caused by specific gene fixation but by increased homozygosity per se.

Genetic studies of South Australian Merino sheep. 2. Environmental effects on wool and body traits at 15-16 months of age

1981 ◽  
Vol 32 (4) ◽  
pp. 657 ◽  
Author(s):  
IP Gregory ◽  
RW Ponzoni
Keyword(s):  
Body Weight ◽  
Surface Area ◽  
Multiple Birth ◽  
Production Traits ◽  
Merino Sheep ◽  
Main Production ◽  
The Difference ◽  
Fleece Weight ◽  
Main Components ◽  
Australian Merino

The effects of years, sex, type of birth (i.e. whether or not multiple birth) and age of dam on 26 wool and body traits of South Australian Merino sheep were estimated by least-squares analysis. Years and sex had highly significant effects on all traits. Of the main production traits, type of birth had a significant effect on body weight, greasy and clean fleece weight and total wool follicle number, while age of dam only had a significant effect on body weight and greasy fleece weight. The possible consequences of failing to correct body weight and greasy and clean fleece weights for type of birth and age of dam were considered and it was concluded that, although in some years correction of these traits may not be warranted, in other years correction may be necessary to prevent selection against fecundity and an increase in the generation interval. The main components contributing to the 6.0 % difference between fleece weights of singles and twins were surface area, total follicle number and wrinkle score. The difference between fleece weights of animals from older ewes and animals from maidens was only 1.5 %; surface area was the main contributor to this deviation.

The Agouti gene: a positional candidate for recessive self-colour pigmentation in Australian Merino sheep

1999 ◽  
Vol 50 (6) ◽  
pp. 1099 ◽  
Author(s):  
Y. M. Parsons ◽  
M. R. Fleet ◽  
D. W. Cooper
Keyword(s):  
Comparative Mapping ◽  
Economic Importance ◽  
The Self ◽  
Positional Candidate ◽  
Chromosome 13 ◽  
Merino Sheep ◽  
Merino Wool ◽  
Agouti Gene ◽  
Mapping Information ◽  
Australian Merino

The occurrence of self-colour pigmentation in the Australian Merino wool flock is of considerable economic importance. The Agouti gene is believed to be responsible for the recessive expression of pigmented fleece. Using comparative mapping information we have investigated the putative homologous ovine map positon of the Agouti gene for linkage to the recessive self-colour phenotype of Australian Merino sheep. Significant results were observed with microsatellites previously mapped to ovine chromosome 13. Comparative data suggest that the ovine Agouti gene would map to the same chromosome, making the Agouti gene a positional candidate for the self-colour phenotype.

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