Genetic variances for liveweight and fleece traits in Merino, Dohne Merino and South African Meat Merino sheep

2001 ◽  
Vol 41 (2) ◽  
pp. 145 ◽  
Author(s):  
S. W. P. Cloete ◽  
S. J. Schoeman ◽  
J. Coetzee ◽  
J. de V. Morris
Keyword(s):  
South African ◽  
Fibre Diameter ◽  
Phenotypic Variance ◽  
Total Phenotypic Variance ◽  
Weaning Weight ◽  
Merino Sheep ◽  
Genetic Variances ◽  
Variance Ratios ◽  
Fleece Weight ◽  
Variance Estimates

(Co)variance estimates for weaning weight, yearling liveweight, clean fleece weight and fibre diameter at yearling age were obtained for Merino, Dohne Merino and South African Meat Merino flocks maintained on the same property. Direct additive genetic variances for weaning weight [expressed as a ratio of the total phenotypic variance (h2, direct heritability)] were estimated at 0.15 for Merinos, 0.21 for Dohne Merinos and 0.32 for South African Meat Merinos. Corresponding maternal variance ratios (m2, including direct maternal variance and permanent environmental maternal variance) were estimated at 0.15, 0.30 and 0.24, respectively. The correlation between direct and maternal variance ratios was high and negative in Dohne Merinos and South African Meat Merinos (–0.72 and –0.53, respectively). Direct heritability estimates for yearling liveweight were 0.30 for Merinos, 0.33 for Dohne Merinos and 0.45 for South African Meat Merinos. Corresponding maternal variance ratios were only significant in the latter 2 breeds, amounting to 0.13 in Dohne Merinos and 0.12 in South African Meat Merinos. For yearling clean fleece weight, h2 and m2 were estimated at 0.28 and 0.12, respectively, for both Merinos and Dohne Merinos. In the case of South African Meat Merinos, only the h2 estimate was significant, at 0.68. Maternal variance ratios for yearling fibre diameter were not significant in any of the breeds, while h2 ranged from 0.58 in Merinos to 0.75 in South African Meat Merinos. Selection progress for yearling traits seems likely in all breeds, depending on the breeding objectives being strived for.

Increasing lamb output by crossing commercial Merino ewes with South African Meat Merino rams

2000 ◽  
Vol 40 (1) ◽  
pp. 11 ◽  
Author(s):  
S. W. P. Cloete ◽  
A. Durand
Keyword(s):  
Survival Rate ◽  
South African ◽  
Coefficient Of Variation ◽  
Fibre Diameter ◽  
Combined Effect ◽  
Weaning Weight ◽  
Slaughter Weight ◽  
Ram Lambs ◽  
Staple Strength ◽  
Fleece Weight

Commercial Merino ewes were randomly allocated to 1 of 2 groups, which were joined either to commercial Merino or South African Meat Merino rams during October 1996 and 1997. Merino rams were involved in 161 joinings, and South African Meat Merino rams in 157 joinings. The proportions of ewes that lambed were independent of the breed of the sire when expressed relative to the number of ewes joined (0.809 and 0.801 in ewes joined to South African Meat Merino and Merino rams, respectively). The proportion of multiple lambs was similarly not affected by the breed of the service sire. Lambs sired by South African Meat Merino rams were on average ( s.e.) heavier (4.17 0.07 v. 3.86 0.07 kg; P<0.01) at birth. They also tended to have a better (0.69 v. 0.59; P<0.10) survival to weaning, and were heavier (26.9 0.6 v. 22.8 0.6 kg; P<0.01) at weaning than purebred Merino contemporaries. The combined effect of the tendency towards an improved survival rate as well as the increased lamb weaning weight resulted in a 36% increase (P<0.01) in lamb output in Merino ewes joined to South African Meat Merino ewes compared with ewes joined to Merino rams. Higher (P<0.01) proportions of ram lambs sired by South African Meat Merino rams reached slaughter weight (about 40 kg) before the onset of the dry Mediterranean summer than purebred Merinos. Two-tooth ewes sired by South African Meat Merino rams were heavier (P<0.01) at 2-tooth age (53.0 0.6 v. 52.0 0.6 kg) than purebred Merinos. The 2-tooth greasy fleece weight of South African Meat Merino sired 2-tooth ewes were lower (3.85 0.08 v. 4.66 0.09 kg; P<0.01), with a lower (66.8 0.6 v. 70.5 0.7 %; P<0.01) clean yield than that of purebred Merinos. This resulted in a marked difference in clean fleece weight between the 2 types (2.56 0.06 v. 3.28 0.06 kg, respectively). Wool produced by South African Meat Merino sired 2-tooth ewes was generally broader (21.8 0.3 v. 20.3 0.3 m; P<0.01) and shorter (87.3 1.3 v. 96.4 1.4 mm; P<0.01) than that of their purebred Merino contemporaries. The coefficient of variation of fibre diameter as well as staple strength was independent of the breed of the sire. Liveweight of adult ewes and wool traits were independent of the breed of the service sire.

Direct and maternal genetic (co)variances for hogget liveweight and fleece traits in Western Australian Merino sheep

2002 ◽  
Vol 53 (3) ◽  
pp. 271 ◽  
Author(s):  
S. W. P. Cloete ◽  
J. C. Greeff ◽  
R. P. Lewer
Keyword(s):  
Genetic Correlation ◽  
Coefficient Of Variation ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Phenotypic Variance ◽  
Selection For ◽  
Fleece Weight ◽  
Variance Estimates ◽  
Western Australian ◽  
Australian Merino

(Co)variance estimates for hogget liveweight, greasy fleece weight, clean fleece weight, clean yield, fibre diameter, and the coefficient of variation of fibre diameter were obtained for a Western Australian Merino resource flock. The flock encompassed 16 medium wool bloodlines and data were available for the period 1982–93. Direct additive genetic variances (h2) — expressed as a ratio of the total phenotypic variance within bloodlines — were estimated at 0.52 for hogget liveweight, 0.44 for greasy fleece weight, 0.42 for clean fleece weight, 0.63 for clean yield, 0.71 for fibre diameter, and 0.62 for coefficient of variation of fibre diameter. Maternal genetic variance estimates were significant (P < 0.05) only in hogget liveweight and fibre diameter, but components within bloodlines were low (0.05 for liveweight and 0.02 for fibre diameter). Direct within-bloodline genetic correlations of hogget liveweight as well as greasy and clean fleece weight with fibre diameter were positive (0.17, 0.31, and 0.31, respectively), suggesting that selection for bigger and heavier cutting sheep would generally lead to a broader fibre diameter. Liveweight was unrelated to clean yield and negatively related to coefficient of variation of fibre diameter (–0.17). Greasy fleece weight was negatively related to clean yield (–0.20). The genetic correlation of clean fleece weight with clean yield was positive (0.37). Wool quantity was, in general, positively related to coefficient of variation of fibre diameter, although the estimated genetic correlations were low (0.12 for greasy fleece weight and 0.07 for clean fleece weight). The genetic correlation between fibre diameter and coefficient of variation of fibre diameter was negative, and fairly low (–0.10). These results are discussed with reference to sheep breeding.

scholarly journals The allometric relationship between mean fibre diameter of mohair and the fleece-free liveweight of Angora goats over their lifetime

2012 ◽  
Vol 52 (1) ◽  
pp. 35 ◽  
Author(s):  
B. A. McGregor ◽  
K. L. Butler ◽  
M. B. Ferguson
Keyword(s):  
South African ◽  
Fibre Diameter ◽  
Cube Root ◽  
Weaning Weight ◽  
Primary Determinant ◽  
Angora Goats ◽  
Fleece Weight ◽  
Log Normal ◽  
Lifetime Effects ◽  
Birth Parity

As mean fibre diameter (MFD) is the primary determinant of mohair price we aimed to quantify the lifetime changes in mohair MFD as Angora goats aged and grew. Measurements were made over 12 shearing periods on a population of Angora goats representing the current range and diversity of genetic origins including South African, Texan and interbred admixtures of these and Australian sources. Records of sire, dam, birthweight, birth parity, liveweight, fleece growth and fleece quality were taken for does and castrated males (wethers) (n = 267 animals). Fleece-free liveweights (FFLwt) were determined for each goat at shearing time by subtracting the greasy fleece weight from the liveweight recorded immediately before shearing. A restricted maximum likelihood growth curve model was developed for relating MFD to FFLwt, age and other measurements. A simple way of describing the results is: MFD = κ (FFLwt)β E; where κ is a parameter that can vary in a systematic way with shearing(age), breed, weaning weight, sire, dam and individual; β is a parameter that is the same for nearly the whole study; and E are independent errors from a log-normal distribution. The analysis shows that = 0.34, with s.e. () = 0.021. Thus, mohair MFD was allometrically related to the cube root of FFLwt over the lifetime of Angora goats. However, the allometric proportionality constant differed in a systematic way with age at shearing, genetic strain, weaning weight, sire, dam and individual. For Texan-breed goats, MFD decreased as weaning weight increased (P = 0.00016). The findings indicate that management factors that affect liveweight and weaning weight have lifetime effects on mohair fibre diameter and therefore the value of mohair and the profitability of the mohair enterprise.

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.

The long-term influence of superphosphate and stocking rate on the production of spring-lambing Merino sheep in the high rainfall zone of southern Australia

1999 ◽  
Vol 50 (7) ◽  
pp. 1179 ◽  
Author(s):  
J. W. D. Cayley ◽  
G. A. Kearney ◽  
G. R. Saul ◽  
C. L. Lescun
Keyword(s):  
Fibre Diameter ◽  
Subterranean Clover ◽  
The Body ◽  
Stocking Rate ◽  
Gross Margin ◽  
Single Superphosphate ◽  
Merino Sheep ◽  
Predetermined Level ◽  
The Mean ◽  
Fleece Weight

The productivity of spring-lambing fine wool Merino sheep grazing pastures sown in 1977 to perennial ryegrass and subterranean clover was assessed from 1989 to 1998. The pastures were fertilised each autumn with single superphosphate at 6 levels, and were stocked at a low, medium, or high stocking rate (SR) at each level of fertiliser. The average phosphorus (P) applied annually since sowing (P ) ranged from 1.6 to 32.9 kg/ha. The SRs used varied with fertiliser level in that they were higher where more fertiliser had been applied, so that the highest SR at each level of fertiliser ensured that the pastures were well utilised. Each ewe raised 1 lamb, which was removed at weaning. The influence of fertiliser on the productivity of the sheep at 4 classes (1–4) of SR (mean SR = 7.1, 10.1, 12.6, and 18.2 ewes/ha for classes 1–4, respectively) was described by: y = A−BCP, where y represents production per sheep (kg), and A, B, and C are constants. For greasy fleece weight, estimates of B and C were 1.59 and 0.84; and for SR classes 1–4, the estimates of A were 5.06, 4.89, 4.78, and 4.46, respectively. For weaning weight of lambs, estimates of B and C were 8.4 and 0.82, and estimates of A were 23.5, 22.7, 21.5, and 20.9 for SR classes 1–4. The mean fibre diameter (µm) of the wool was described by: D = 14.18+1.48 GW, where GW is the mean greasy wool produced annually per sheep (kg) averaged over all sheep and years for each of the 18 treatments. The price (cents/kg) of wool with a fibre diameter D (P D) was given by: P D = 12197+4.94P2 + 688D−0.1945P20D − 5810√D, where 20 µm wool is P20 cents/kg. Supplements were fed if the body condition of ewes fell to a predetermined level. The supplement fed per ewe each year (S), expressed as metabolisable energy (in MJ) was described by: S = −602 − 44.1S R + 178.5P + 8.71S R P +539 √SR− 338.5√P−70.8P√SR, where S R and P represent the mean stocking rate (ewes/ha) and mean P applied annually. When a current set of costs and prices was applied to these equations, the maximum gross margin for a SR of 7.1 ewes/ha was $AU119/ha with 8.6 kg P/ha applied annually, and $AU262/ha for SR of 18.2 ewes/ha with 17.6 kg P/ha applied annually. If income derived from sheep is maintained constant, intensifying the sheep enterprise from the low to the high SR system would involve increasing sheep numbers by about 17%, but would release about 55% of the farm’s area for another purpose.

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.

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

1969 ◽  
Vol 20 (1) ◽  
pp. 151
Author(s):  
O Mayo ◽  
JC Potter ◽  
RE Brady ◽  
CW Hooper
Keyword(s):  
Fibre Diameter ◽  
Index Method ◽  
Visual Method ◽  
Merino Sheep ◽  
Index Group ◽  
Agricultural College ◽  
Selection For ◽  
The Difference ◽  
Fleece Weight ◽  
Selection Of

This paper reports the results of an experiment carried out at Roseworthy Agricultural College from 1953 to 1966 comparing two bases of selection of rams: (1) visual appraisal (the "visual" method); (2) visual culling of 70% of rams followed by selection of breeding animals from the remaining 30% on the basis of clean fleece weight (the "index" method). No selection for fleece weight was practiced on ewes. Seven rams were used in each of the two flocks, and six of the seven were replaced each year by 16-month-old animals from the succeeding drop, the seventh being a year older. Rams used for breeding in the Index flock were significantly higher in clean fleece weight than those of the Visual flock, and were higher, though not always significantly so, in greasy fleece weight. This led to a divergence between the flocks for clean fleece weight (P < 0.05), with an increase of c. 0.05 lb per year per head for the Index animals over the Visual animals. The Index rams were more wrinkly and lighter, on the whole, than the Visual rams, and the wrinkly effect carried over into their offspring with a slight divergence apparent, the Index animals becoming more wrinkled than the Visual (P < 0.05). In fibre diameter there were no differences between selected animals or between flocks. Visual rams tended to have more crimps per inch in their wool, and this was observed in the flocks also, but the divergence was not significant (P > 0.05). Index rams had longer wool than Visual rams, with the difference generally significant within years, and this tendency carried over in a lesser manner to the flocks. Fleece density was generally greater in the Index group, though not usually significantly so. This experiment did not include a randomly bred control flock, but was rather designed to compare two practical methods of selecting rams. Merits of this scheme are discussed in the light of both groups' failure to show increases in fleece weight over the course of the experiment

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.

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