The efficiency of conversion of feed to wool in Merino flocks selected for and against fleece weight

1963 ◽  
Vol 3 (11) ◽  
pp. 269 ◽  
Author(s):  
W Ahmed ◽  
RB Dun ◽  
RJ Winston
Keyword(s):  
Body Weight ◽  
Feed Intake ◽  
Relative Importance ◽  
Merino Sheep ◽  
Wool Growth ◽  
Cent Increase ◽  
The Difference ◽  
Fleece Weight

The efficiency of conversion of feed to wool was measured in three jocks of Peppin Merino sheep, namely : Fleece Plus-Selected for nine years on high clean fleece weight ; Fleece Minus-Selected for nine years on low clean fleece weight ; Random-An unselected, control flock. Ten 18 month old ewes from each of these flocks were individually housed and fed ad lib on hammer-milled lucerne hay for 54 weeks. Highly significant differences between flocks were observed in feed intake, wool growth, and efficiency of conversion of feed to wool. The relative productive levels for the Fleece Plus, Random and Fleece Minus flocks were-for feed intake, 108 : 100 : 88-for clean fleece weight, 118 : 100 : 70-and for efficiency 109 : 100 : 79. The correlation between efficiency and daily feed intake was very highly significant and negative within each flock, (-0.918, -0.929 and -0.924, for Fleece Plus, Random and Fleece Minus flocks respectively), whereas the correlation between jocks was significantly positive, r = 0.997. The relative importance of the factors determining the 18 per cent increase in clean fleece weight of the Fleece Plus over the Random flock was : efficiency, 55 per cent and feed intake, 45 per cent-and comparing the Random to the Fleece Minus flock : efficiency, 60 per cent and feed intake, 40 per cent. Approximately half the difference in feed intake was independent of body weight.

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.

Feed intake, liveweight and wool growth rate in Merino sheep with different responsiveness to low- or high-quality feed

2002 ◽  
Vol 42 (4) ◽  
pp. 399 ◽  
Author(s):  
N. R. Adams ◽  
D. Blache ◽  
J. R. Briegel
Keyword(s):  
Growth Rate ◽  
Feed Intake ◽  
Poor Quality ◽  
The Other ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
High Quality ◽  
Merino Sheep ◽  
Wool Growth ◽  
Fleece Weight

A previous field trial using 30 sheep from each of 3 strains of Merino sheep (designated F, M and B) found that wool growth rate in strain B changed less throughout the year, compared with the other 2 strains. The present study examined components of liveweight loss on dry pasture with low protein and low digestibility to detect underlying relationships with the subsequent responsiveness of wool growth rate to young green pasture. Strain B lost less liveweight when grazed on dry (poor-quality) pasture, but lost more liveweight on sparse green pasture, than the other 2 strains. The rate of liveweight loss was not related to fatness on dry pasture, but was related to fatness on green pasture. The plasma concentration of leptin at the start of winter was related to clean-fleece weight (P<0.01). A second study examined the role of voluntary feed intake in strains M and B, offered low (56%�digestibility) and then high (70% digestibility) quality feed ad libitum in individual pens. Wool growth rate increased (P<0.001) on the better feed and tended to increase more (P = 0.06) in strain M. Feed intake increased (P�= 0.01) more in Strain M when offered good-quality feed. Fatness affected feed intake similarly in both periods. The results indicate 2 mechanisms that differed between feed conditions. First, sheep differed in their capacity to increase wool growth on high-quality feed, associated with the capacity to increase feed intake. Second, fatness was associated with the differential liveweight response to good or poor quality feed, although it was not clear whether it acted through appetite. It is hypothesised that the capacity to increase wool growth rate on good feed may be associated with a greater decrease in protein synthesis rate on poor quality pasture. This may result in a lower drive to eat and so a greater liveweight loss on poor pasture.

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.

N-[5-(4-Aminophenoxy)pentyl]phthalimide as a potential defleecing agent and its effect on wool growth

1980 ◽  
Vol 31 (4) ◽  
pp. 791
Author(s):  
DA Tunks ◽  
RDG Rigby ◽  
AM Downes ◽  
JA Lamberton ◽  
BA Panaretto ◽  
...  
Keyword(s):  
Growth Rate ◽  
Body Weight ◽  
Oral Dose ◽  
Feed Intake ◽  
Merino Sheep ◽  
Dose Rates ◽  
Wool Growth

Merino sheep, offered feed at two levels of intake, were given an oral dose of N-[5-(4-am1nophenoxy)- pentyllphthahmide at rates varying over 100-800 mg/kg body weight. Consistent defleecing was obtained at dose rates of 400 nig/kg and above. Feed intake did not Influence defleecing activity. lntravenous infusion of smaller amounts also allowed defleecing. Wool growth rate following dosing was not affected by a dose of 100 mg/kg, but doses of 200 and 400 mg/kg caused depressions of c. 15 and c. 70% respectively in the rate of wool growth in the 2 weeks after dosing. Blindness was observed In one sheep dosed at 400 mg/kg and In all sheep dosed at higher rates

Wool and liveweight responses to nutrition by Merino sheep genetically selected for high or low staple strength

1997 ◽  
Vol 48 (8) ◽  
pp. 1129 ◽  
Author(s):  
N. R. Adams ◽  
J. R. Briegel ◽  
A. J. M. Ritchie
Keyword(s):  
Fibre Diameter ◽  
Rate Of Change ◽  
Merino Sheep ◽  
Low Protein ◽  
Wool Growth ◽  
Good Nutrition ◽  
The Difference ◽  
Staple Strength ◽  
Fleece Weight ◽  
Protein Diets

The biological mechanisms underlying differences in wool staple strength were examined in 2 groups of Merino sheep that have been genetically selected for high or low staple strength, while holding fibre diameter constant. The sheep were fed below maintenance for 87 days, and then re-fed ad libitum for 63 days with a diet containing either 9% or 23% crude protein, in a cross-over design, after which they returned to the paddock until shearing. The fleeces of the 2 groups differed in staple strength (25·2 v.17·5 N/ktex, P < 0·001) but were similar in mean fibre diameter and clean fleece weight. However, the pattern of wool growth was different. When fed below maintenance, sheep from the sound group grew more wool than sheep from the tender group (P < 0·05), but lost more liveweight (P < 0·01). During re-feeding, the sound sheep grew less wool than the tender sheep (P < 0·05), but gained more liveweight. The mean fibre diameter at the point of break was similar in both groups. Immediately after re-feeding, the fibre diameter increased more rapidly in the tender group than in the sound (P < 0·001), but a similar difference was observed between the high and low protein diets, with no effect on staple strength. The sound sheep had a lower standard deviation of fibre diameter than the tender sheep (P < 0·001), both in the whole fleece and in 3-weekly midside patches. The data indicated that the variability of fibre diameter between fibres made a larger contribution than the variability along fibres to the difference between the groups in overall variability of fibre diameter. The sheep were then grazed together at pasture for a second year and again differed in staple strength. In addition, the sound sheep grew less wool on green spring pastures and had a lower clean fleece weight (P < 0·05). The differences in wool growth rates between sheep from the sound and tender lines depended more on whether pasture was green than on the amount of pasture available. We conclude that the difference in staple strength between the sound and tender groups was most closely associated with the variability between fibres in diameter, and was also affected by a difference in variation in diameter along the fibres. Staple strength was not affected by the amount of wool at the point of break, or by the rate of change in fibre diameter after feeding. The sheep in the sound group grew less wool than those in the tender group when on good nutrition.

Genetic evaluation of production traits between and within flocks of Merino sheep. I. Hogget fleece weights, body weight and wool quality

1989 ◽  
Vol 40 (2) ◽  
pp. 433 ◽  
Author(s):  
SI Mortimer ◽  
KD Atkins
Keyword(s):  
Body Weight ◽  
Environmental Effects ◽  
Genetic Variance ◽  
Research Centre ◽  
Production Traits ◽  
Merino Sheep ◽  
Wool Production ◽  
Phenotypic Correlations ◽  
Genetic And Phenotypic Correlations ◽  
Fleece Weight

Wool production traits were measured on Merino hogget ewes in an unselected multiple-bloodline flock over a 7-year period at Trangie Agricultural Research Centre, N.S.W. The traits measured were greasy fleece weight (GFW), skirted fleece weight (SKFW), yield (Y), clean fleece weight (CFW), fibre diameter (FD), body weight (BWT) and staple length (SL). These measurements were used to examine genetic differences between and within flocks of Merino sheep, and to estimate heritability of and genetic and phenotypic correlations among these traits. Significant strain, flock within strain and flock effects were present for all traits. Interactions between these effects and year were non-significant. Within-flock genetic variance was always larger than between-flock within strain genetic variance for each trait. The influence of environmental effects on these traits was also examined. The environmental effects of birth-rearing type, age at observation and age of dam together accounted for about 7-10% of the total within-flock variation in fleece weights and body weight.After adjusting for significant environmental effects, paternal half-sib heritability estimates were 0.29 �. 0.06 for GFW, 0.22 � 0.05 for SKFW, 0.35 � 0.05 for Y, 0.30 �0.06 for CFW, 0.48 �0.07 for FD, 0.34 �. 0.06 for BWT and 0.44 �0.07 for SL. Estimates for genetic and phenotypic correlations were in agreement with published estimates except for the genetic correlation between CFW and FD (0.40 �. 0.11), and the genetic correlations involving BWT, which were essentially zero. The implications of the results of this study for the genetic improvement of Merino sheep for wool production are discussed.

Seasonal variations in wool growth and heat tolerance of sheep. I. Wool growth

1960 ◽  
Vol 11 (1) ◽  
pp. 75 ◽  
Author(s):  
M Wodzicka
Keyword(s):  
Body Weight ◽  
Day Treatment ◽  
The Other ◽  
Seasonal Rhythm ◽  
Group Iii ◽  
Wool Growth ◽  
Group I ◽  
The Mean ◽  
Group Ii ◽  
The Difference

The monthly wool growth of three groups of rams was studied at Beltsville, Maryland. Group I received natural daylight (at 38° 53' N.) and was shorn monthly. Group II had a 7:17 hours of daylight to hours of darkness rhythm and was shorn every 6 months, once in winter and once in summer. Group III received natural daylight and was likewise shorn every 6 months. The rams of all groups produced more wool in summer than in winter. This difference was significant (P<0.001). The mean body weight and food intake were both greater in the winter months, which indicated that the seasonal rhythm of wool growth was not a consequence of poorer feeding in winter. The rams which were shorn monthly (group I) grew considerably more wool than the other two groups, but the difference was not statistically significant. The short-day treatment of group II did not increase the annual wool production nor decrease the seasonal rhythm of wool growth. The balance of evidence from this and other experiments indicates that temperature rather than light controls the seasonal rhythm of wool growth.

The value of production from a clipped measured area as an index of fleece weight.

1955 ◽  
Vol 6 (1) ◽  
pp. 91 ◽  
Author(s):  
FHW Morley ◽  
LW Lockart ◽  
EC Davis
Keyword(s):  
Body Weight ◽  
Correlation Coefficient ◽  
Unit Area ◽  
Multiple Correlation Coefficient ◽  
Multiple Correlation ◽  
Merino Sheep ◽  
Wool Production ◽  
Fleece Weight ◽  
Selection Of

The correlation between greasy wool production per unit area, obtained by clipping and measuring an area of about 100 cm² on the midside, and greasy fleece weight at shearing was about 0.58. Wool production from such an area over periods of 7½ or 3½ months was almost as useful as production for 11 months for predicting greasy fleece weight. The multiple correlation coefficient between greasy fleece weight as the dependant variable and production per unit area and 11-months' body weight was 0.79 in 66 rams and 0.71 in 82 ewes. The inclusion of fold score did not improve prediction appreciably. The equation W = P/110 + B1 /12 may be used to predict greasy fleece weight (lb), W, where P is production over 11 months of greasy wool (mg/cm²) and B1 is 11-months' body weight (Ib). A table of this function is included so that values may be read directly. The technique may be a useful aid to selection of Merino sheep if recording of actual fleece weights is difficult or impossible. Nevertheless it should not be regarded as more than a moderately accurate substitute for actual fleece-weighing.

Stimulation of wool growth by thyroxine implantation. II. Feed intake of grazing Merino wethers treated repeatedly with thyroxine.

1964 ◽  
Vol 15 (4) ◽  
pp. 676 ◽  
Author(s):  
LJ Lambourne
Keyword(s):  
Organic Matter ◽  
Feed Intake ◽  
Sheep Grazing ◽  
Wool Production ◽  
Wool Growth ◽  
Digestible Organic Matter ◽  
The Difference ◽  
Maintenance Requirements ◽  
Substantial Rise ◽  
Stimulation Of

Estimates have been made of the feed intake of wethers that received implantations of 60 mg thyroxine every 3 months, and of untreated sheep, grazing together. The estimated intake of digestible organic matter (D.O.M.) by treated wethers was higher than that of controls in 24 out of 27 measurement periods. The difference in feed intake was least in the iirst month after implantation, when the treated sheep lost weight, and greatest in the second and third months when the treated sheep were regaining weight. The overall increase in intake resulting from thyroxine treatment (20–25%) was greater than the increase in wool production (7% greasy weight, 3-7 % clean weight), and the efficiency of wool production was therefore lower in thyroxinetreated wethers. From the relationships between feed intake and rate of weight change it was concluded that in the month after implantation, when pulse rates indicated a substantial rise in metabolic rate, the maintenance feed requirement was raised from about 560 g to about 780 g D.O.M. per day. Observations in two winters with recently shorn sheep gave estimates of maintenance requirements for untreated wethers ranging from 850 to 1300 g D.O.M. per day. During recovery from repeated thyroxine implantation the wethers gained in weight no more efficiently than the controls. The mechanism of action of exogenous thyroxine is discussed in the light of these and other data.

Relationships among clean wool weight and its components. 2. The effect of maternal handicap and its influence on selection.

1961 ◽  
Vol 12 (5) ◽  
pp. 974 ◽  
Author(s):  
HN Turner
Keyword(s):  
Body Weight ◽  
Population Density ◽  
Selection Differential ◽  
Average Difference ◽  
Genetic Progress ◽  
Main Effect ◽  
Current Production ◽  
The Difference ◽  
Fleece Weight

The average difference in clean wool weight between handicapped (twins and the progeny of young ewes) and unhandicapped (singles, the progeny of adults) animals of both sexes, born in the same year, was -0.34 � 0.07 lb (365 days' growth shorn at 16 months of age). 87% of the difference in wool weight arose from a difference in total number of fibres (or follicles) per sheep, the difference in output per follicle being negligible. Body weight, wrinkle score, and follicle population density were all lower in the handicapped animals. The difference in total follicle population arose from a deficiency in secondary but not in primary follicles. If the handicapped animals are not identified at selection, they will suffer a heavier culling rate if selection is on fleece weight, and estimates of differential culling rates are given. The effect on genetic progress and current production is, however, negligible with a handicap of this size. In fact, when the handicapped animals are twins, there are more animals available for selection than there would have been if the births had been single, and the higher selection differential arising from the smaller proportion saved more than offsets any deficiency from the handicap. The main effect of not identifying handicapped animals at selection is that twins will be selected against, with a resultant lowering of the twinning rate. The suggestion is made that management might possibly overcome the handicap, at least in part.

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