The relationship of lamb birthcoat to adult fleece structure in a strain of Merino sheep

1958 ◽  
Vol 9 (4) ◽  
pp. 567 ◽  
Author(s):  
PG Schinckel
Keyword(s):  
Body Weight ◽  
Fibre Diameter ◽  
Merino Sheep ◽  
Gene System ◽  
Weight Yield ◽  
Fleece Weight ◽  
Relationship Of ◽  
The Relationship ◽  
Staple Length

Variability of the lamb birthcoat has been studied in relation to adult fleece characteristics. Coarse birthcoats were associated with increased variability of fibre diameter and decreased crimp rate. The increased variability of fibre diameter resulted from a significant increase in the diameter of primary fibres and a small, but statistically non-significant, decrease in the diameter of secondary fibres. There was no relation between birthcoat grade and body weight, clean fleece weight, yield, staple length, follicle density, follicle ratio, mean fibre diameter, or skin folds. It is postulated that there is a gene system in the Merino the effect of which is to cause variation in the amount of wool produced by the different follicle types. Increased "dosage" of genes of the system endows primary follicles with increased productivity and secondary follicles with decreased productivity. This is expressed in the form of increased halo-hair abundance in the lamb and increased differences between the diameters of primary and secondary fibres in the adult.

scholarly journals Evidence of a unique developmental mechanism specifying both wool follicle density and fibre size in sheep selected for single skin and fleece characters

1989 ◽  
Vol 53 (1) ◽  
pp. 57-62 ◽  
Author(s):  
G. P. M. Moore ◽  
N. Jackson ◽  
J. Lax
Keyword(s):  
Fibre Diameter ◽  
Statistical Association ◽  
Merino Sheep ◽  
Developmental Mechanism ◽  
Negative Linear Correlation ◽  
Foetal Life ◽  
Wool Follicle ◽  
Fleece Weight ◽  
The Relationship ◽  
Staple Length

SummarySkin and fleece traits have been characterized in four lines of Merino sheep selected for high- and low-fibre diameter (D±) and staple length (L±) from a medium-woolled flock. Over a period of 20 years, each line responded in the desired direction, producing fleeces composed of thick or thin fibres and long or short wool staples. However, variations in the amounts of wool grown that might be expected from these procedures were compensated by changes in unselected characters. Thus a predicted difference in fleece weights between high and low staple length lines was reduced by an increase in fibre crimp frequency in L− sheep. Similarly, changes induced in fibre diameter in the D lines resulted in small effects on fleece weight in comparison to the large (and inverse) effects on follicle numbers. Towards the end of the selection regime, mean follicle density in D− sheep was twice that of D+ sheep. This intriguing response within the follicle population was examined further: an analysis of the relationship between follicle density and fibre diameter amongst the four lines revealed a highly significant, negative linear correlation. The implication of this statistical association is that the numbers of follicles initiated in skin during foetal life had a direct bearing on the sizes of wool fibres eventually produced. It was concluded that both features must be under the control of a single developmental mechanism. Since the expression of each of the characters is separated in time, the mechanism must be activated during the earlier event, i.e. at or before the phase of follicle initiation.

Body-weight-fleece-weight relationships in a strain of Merino sheep

1956 ◽  
Vol 7 (1) ◽  
pp. 57 ◽  
Author(s):  
PG Schinckel
Keyword(s):  
Body Weight ◽  
Body Surface ◽  
Unit Area ◽  
Merino Sheep ◽  
Wool Production ◽  
Significant Difference ◽  
The Mean ◽  
Fleece Weight ◽  
Relationship Of ◽  
The Relationship

The relationship of body weight to wool production was examined in a flock of Merino sheep of South Australian strain over a period of 7 years. In only one out of 10 groups examined was there a significant correlation between body weight and the amount of clean wool produced per unit area of midside skin. It is concluded that body weight and wool production per unit area of body surface are independent. In all groups there was a highly significant correlation between clean fleece weight and clean wool per unit area of body surface in the midside region. The regression of log fleece weight on log body weight was determined in 15 groups. In no case was the regression coefficient significantly different from 0.60. As the regression of log surface area on log body weight in sheep is of the order of 0.60, it is concluded that wool production is proportional to fleece-bearing surface. The mean regression coefficients of log fleece weight on log body weight, calculated within sire and year groups, were: rams, 0.52 ± 0.056; ewes, 0.61 ± 0.038; wethers, 0.30 ± 0.068. There were no significant differences between sires in the regression of log fleece weight on log body weight. There were, however, highly significant differences between sire groups in mean log fleece weight, after adjustment for differences in log body weight. Skin areas 3 by 3 cm were tattooed on the left midside of 24 lambs at 1 month of age. The wool produced on these areas, and the areas of the tattoos, were measured at 4-monthly intervals from 4 months of age until 28 months. The amount of wool produced m7as proportional to the area in each of the six periods. There was also a highly significant difference between periods and between sheep in the amount of wool produced after adjustment for differences in tattoo area.

Genetic studies of South Australian Merino sheep. 3. Heritabilities of various wool and body traits

1982 ◽  
Vol 33 (2) ◽  
pp. 355 ◽  
Author(s):  
IP Gregory
Keyword(s):  
Body Weight ◽  
Fibre Diameter ◽  
Skin Thickness ◽  
Production Traits ◽  
Primary Follicle ◽  
Merino Sheep ◽  
Main Production ◽  
Fleece Weight ◽  
Australian Merino ◽  
Staple Length

Heritabilities have been estimated for a large number of quantitative and qualitative wool and body traits recorded on two flocks of South Australian Merino sheep over a 12-year period. Data were unadjusted for fixed environmental effects and so the estimates are applicable to the heterogeneous populations found in most practical situations. Dam-offspring heritabilities of quantitative traits ranged from 0.15 for primary follicle number to 0.63 for body weight. Greasy and clean fleece weights, percentage clean yield, staple length, crimps per inch, fibre diameter, secondary and total follicle number, skin thickness, coefficient of variation of fibre diameter and secondary/primary follicle ratio had moderate to high heritabilities. Dam-offspring heritabilities of qualitative traits ranged from 0.12 for weather damage of the fleece to 0.75 for birthcoat. Total folds, face cover and hocks had high heritabilities, and wool character, type of staple formation and wool quality had moderate heritabilities. The main production traits (body weight, greasy fleece weight, yield, clean fleece weight, staple length, fibre diameter and total follicle number) were corrected for variation due to type of birth and age of dam and their heritabilities re-estimated. No change occurred in the half-sib heritabilities; dam-offspring heritabilities increased by an average of 0.05.

Response to partial selection on clean fleece weight in South Australian strong-wool Merino sheep

1970 ◽  
Vol 21 (3) ◽  
pp. 541 ◽  
Author(s):  
O Mayo ◽  
DW Cooper ◽  
RE Brady ◽  
CW Hooper
Keyword(s):  
Body Weight ◽  
Birth Weight ◽  
Blood Group ◽  
Fibre Diameter ◽  
Skin Thickness ◽  
Merino Sheep ◽  
Fleece Weight ◽  
Australian Merino ◽  
Staple Length

The associations between 10 production characters and fertility at the R blood group, haemoglobin, and transferrin loci have been examined in two flocks of South Australian Merino sheep. The production characters were birth weight, hogget body weight, hogget wrinkle score, greasy fleece weight, clean fleece weight, staple length, degree of crimp, fibre diameter, fleece density, and skin thickness. No evidence of any real association was found. The significant associations which were found are ascribed either to chance or to the impossibility of eliminating sire effects from the analysis.

Effect of stocking rate on fleece measurements and their relationships in merino sheep

1976 ◽  
Vol 27 (1) ◽  
pp. 163 ◽  
Author(s):  
DH White ◽  
BJ McConchie
Keyword(s):  
Fibre Diameter ◽  
Major Determinant ◽  
Stocking Rate ◽  
Merino Sheep ◽  
Wool Production ◽  
Rate Experiment ◽  
Fleece Weight ◽  
One Year ◽  
Staple Length

The wool characteristics of Merino wethers were measured for 6 years in a stocking rate experiment. The decline in fleece weight due to increasing stocking rate from 4.9 to 12.4 sheep per hectare was usually accompanied by a reduction in fibre diameter and staple length and an increase in staple crimp frequency. The magnitude of these responses differed considerably between years; in one year clean fleece weight was reduced by 50%, with an associated reduction of 5 µm in mean fibre diameter and one of 2 cm in staple length. In four of the six years of the experiment, variation in fibre diameter accounted for at least 50% of the variation in wool production between stocking rate treatments. The relationships between clean fleece weight and fibre diameter were similar between years, mean fibre diameter being reduced by about 1.8 �m for each kilogram reduction in clean fleece weight. Fibre diameter is the major determinant of wool price, and this information should improve the prediction of economic responses to changes in stocking rate.

A comparison of the topmaking performance of wool from sheep selected by index and visual methods

1999 ◽  
Vol 39 (8) ◽  
pp. 941 ◽  
Author(s):  
A. L. Vizard ◽  
K. A. Hansford
Keyword(s):  
Body Weight ◽  
Coefficient Of Variation ◽  
Selection Index ◽  
Fibre Diameter ◽  
Visual Assessment ◽  
Index Selection ◽  
Visual Methods ◽  
Merino Sheep ◽  
Fleece Weight ◽  
Index Value

Summary. The topmaking performance of fleeces from sheep that were ranked high or low on index selection using objective measurement was compared with that of sheep from the same flock that were ranked high or low on visual assessment. A flock of 451 15-month-old fine-wool Merino sheep were classed by 2 experienced fine-wool sheep classers into 3 grades: best, average and culls. Forty-four sheep were assessed as ‘best’ and 77 sheep were graded as ‘culls’ by both classers. These sheep were defined as the ‘best visual’ and ‘worst visual’ sheep, respectively. Measurements of clean fleece weight, mean fibre diameter, coefficient of variation of fibre diameter and body weight were used in a selection index to rank all sheep in the flock. The selection index was designed to rapidly reduce mean fibre diameter and slowly increase clean fleece weight, whilst maintaining staple strength and body weight. The 44 sheep with the highest index value were defined as ‘best index’ sheep and the group of 77 sheep with the lowest index or obvious physical faults were defined as the ‘worst index’ sheep. Twenty-five fleeces were randomly selected from each of the ‘best’ and ‘worst visual’, ‘best’ and ‘worst index’ sheep for individual processing through to top. The fleeces from the ‘best index’ sheep produced greater quantities of tops that were significantly finer, longer, of lower curvature and produced less noil than all other groups. In contrast to the large difference in quality between tops from the ‘best’ and ‘worst index’ sheep, there was little difference in quality between tops from the ‘best’ and ‘worst visual’ sheep. This indicates that the traditional wool producer views of wool quality are unrelated to processing performance. It was concluded that Merino sheep selected by index selection using direct measurement of fleece weight, mean fibre diameter and coefficient of variation of diameter as selection criteria produced greater quantities of wool of superior processing performance to that from sheep selected using visual assessment.

Comparison of estimates of repeatability and heritability for some production traits in Merino rams and ewes. 2. Heritability

1960 ◽  
Vol 11 (4) ◽  
pp. 604 ◽  
Author(s):  
SSY Young ◽  
Turner H Newton ◽  
CHS Dolling
Keyword(s):  
Body Weight ◽  
Population Density ◽  
Sex Difference ◽  
Fibre Diameter ◽  
Production Traits ◽  
Merino Sheep ◽  
Lower Figure ◽  
Selection Of ◽  
Australian Merino ◽  
Staple Length

Heritability estimates were calculated for 10 traits in rams and ewes of a medium-woolled strain of Australian Merino sheep. The traits were greasy wool weight, clean scoured yield, clean wool weight, body weight, wrinkle score, face cover score, fibre population density, fibre diameter, staple length, and crimps per inch. Estimates were made by dam-offspring correlations, measurement on the dams being at 15-16 months, on daughters at 15-16 months, and on sons at both 10-12 and 15-16 months. All estimates for both sexes lay between 0.3 and 0.6, except for fibre population density (0.24) and fibre diameter (0.12) in rams at 15-16 months and for clean wool weight (0.29) and face cover score (0.29) in rams at 10-12 months. The only significant sex difference lay in the lower figure for fibre diameter in rams at 15-16 months, but this is of doubtful importance as the corresponding figure for rams at 10-12 months (0.37) did not differ significantly from the ewe figure. All traits may be considered highly heritable, and the high values for the yearling rams indicate that consideration might be given to the selection of rams for production traits at an earlier age than the traditional one of 18 months or older.

scholarly journals A Relationship Between Sulphur Content of Wool and Wool Production by Merino Sheep

1967 ◽  
Vol 20 (1) ◽  
pp. 153 ◽  
Author(s):  
PJ Reis ◽  
DA Tunks ◽  
OB Williams ◽  
AJ Williams
Keyword(s):  
Body Weight ◽  
Unit Area ◽  
Sulphur Content ◽  
Merino Sheep ◽  
Wool Production ◽  
Weight Index ◽  
Wool Growth ◽  
The Mean ◽  
Fleece Weight ◽  
The Relationship

The sulphur content of wool from 66 Peppin Merino wethers maintained together at pasture was measured in midside staples representing 49 weeks growth. The distribution of sulphur values was normal with a mean of 3�43 % and a range of 3�08-3�92 %. The sulphur content of the wool was inversely related to wool production among these sheep. There were no significant differences in the relationship when wool production was expressed as fleece weight index (F.W.I.), i.e. clean fleece weight/body weight (r = -0�48), as clean fleece weight (r = -0�42), or as wool growth per unit area of skin (r = - 0�37). The mean sulphur content of wool from sheep with the 10 highest values for F.W.I. was 3�27%, compared with a mean of 3 �55% sulphur for wool from sheep with the 10 lowest values for F.W.I.

The influence of the poll gene on certain production characters of Merino sheep

1958 ◽  
Vol 9 (4) ◽  
pp. 553 ◽  
Author(s):  
RB Dun
Keyword(s):  
Body Weight ◽  
Deleterious Effect ◽  
Practical Importance ◽  
Specific Effect ◽  
Chi Square ◽  
Merino Sheep ◽  
Horn Growth ◽  
Fleece Weight ◽  
Staple Length

The results of a series of matings of Merino sheep of the form heterozygous poll rams (Pp) x knobbed ewes (pp), are presented. The phenotypic ratio poll progeny : horned progeny was 75:73 for rams and 81:94 for ewes. These were not significantly different from the expected 1:1 ratio. The 75 Pp rams had horn growth varying in length from 1/2 in. to 13 in. One known poll ram phenotype, depressions at the horn sites, was not seen. Comparisons were made within sires of Pp and pp progeny for a series of production measurements. Pp rams cut 4.09 per cent. more clean fleece weight than pp rams, while Pp ewes cut 4.47 per cent. less than pp ewes. This genotype-sex interaction was further examined by comparing sexes for the ratio of positive to negative within-sire differences. There were highly significant chi-square values for greasy fleece weight, clean fleece weight, and body weight. The differences in clean fleece weight were largely accounted for by differences in body weight and staple length. Fold score differences were negligible. The hypothesis suggested as an explanation for these results is that the Merino poll gene P is associated with a small deleterious effect when heterozygous. The effect is apparent only in ewes where the specific effect is the removal of small bony knobs. A subsidiary hypothesis is that in rams the deleterious effect of P is over-compensated by the nutritive benefits derived from the absence of the large ram horns. The practical importance of these findings is discussed.

The 'Lustre' mutation in Merino sheep

1967 ◽  
Vol 7 (27) ◽  
pp. 296 ◽  
Author(s):  
BJ McGiurk ◽  
BF Short
Keyword(s):  
Body Weight ◽  
Autosomal Gene ◽  
Merino Sheep ◽  
Fleece Weight ◽  
Staple Length

The Lustre mutation was reported by Short (1958) who concluded that it was inherited as a single dominant autosomal gene. In five matings, from 1960 to 1965, rams heterozygous for Lustre were mated to Normal Merino ewes. From these matings 543 Normal and 469 Lustre lambs were born, a result which deviates significantly from the 1 : 1 ratio expected (P<0.05). Significantly higher proportions of Lustre lambs were assisted at birth (20.0 per cent v 13.8 per cent) and died before weaning (34.8 per cent v 21.7 per cent) (P<0.05). The greater mortality of Lustre lambs was most marked in the periods before birth and between birth and four days of age. Lustre lambs were lighter at birth (P<0.05) but the differences in body weight between Normal and Lustre ewes at weaning and following the two-tooth shearing were small and not significant. At the two-tooth shearing the clean fleece weight of Lustre ewes was 56 per cent that of Normal Merinos (P<0.05). The components of fleece weight mainly responsible for this reduction were skin wrinkle, staple length, and follicle density (all P<0.05).

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