Lamb mortality and growth to weaning in commercial Merino flocks in Western Australia

1992 ◽  
Vol 43 (6) ◽  
pp. 1399 ◽  
Author(s):  
RW Kelly
Keyword(s):  
Western Australia ◽  
Fibre Diameter ◽  
Mortality Rates ◽  
Unit Change ◽  
Condition Score ◽  
Average Condition ◽  
The Mean ◽  
Staple Strength ◽  
Fleece Weight ◽  
Highly Correlated

Eighteen farm flocks of four-tooth Merino ewes (average of 371 ewes at lamb marking, range 278 to 511) were studied in 1987/88 ( n =8 ) and 1988/89 (n=10) over the period from 2 to 4 weeks pre-joining until 12 weeks post-lambing. All farms were located in the south-west of Western Australia, and the flocks started lambing between mid-April and mid-July. The average liveweights of ewes pre-joining ranged over 40.2 to 61.8 kg, and average condition scores ranged from 2.2 to 4.2. Mean liveweight changes of the ewes ranged over losses of up to 8.5 kg to gains of up to 10.4 kg between consecutive recordings at 2 to 3 month intervals up to 12 weeks post lambing, and condition score changes ranged over minus 1.2 to plus 1.2. The greatest losses in liveweight and condition score in many flocks corresponded with the period from mid-pregnancy to marking, the time of greatest nutrient demand of the ewe. There was considerable variation between flocks in the percentage of dry ewes (2.9 to 17.7%), lambs born per ewe present at marking (83.0 to 147.3%), lambs alive per ewe present at marking (66.3 to 123.2%), and lamb deaths as a percentage of total lambs born (10.9 to 29.8%). For single and twin-born lambs, the percentage of lamb deaths between flocks ranged from 6.0 to 19.9% (mean = 11.0%) and 19.1 to 63.2% (mean = 33.1%) respectively. Of the ewes giving birth to twins, an average of 9.6% lost both lambs. The mean birthweights were 4.4 kg (range 3.6 to 5.1 kg) for singles and 4.0 kg (range 3.3 to 4.5 kg) for twins, and were highly correlated (r = 0 - 74, n = 13 flocks, P<0.01). Lamb growth to marking averaged 232 g head-1 day-1 and 205 g head-1 day-1, and from marking to weaning 198 g head-1 day-1 and 193 g head-1 day-1 for single and twin-born lambs respectively. The mortality rates of both single and twin-born lambs were highly correlated with mean liveweight of the ewes at mid-pregnancy (r = -0.64, P<0.01; r = -0.75, P<0.001; respectively). A kilogram increase in mean liveweight at mid-pregnancy was associated with declines in the mortality rates of single-born lambs of 0.7% units (s.e. = 0.23), and of twin-born lambs of 2.2% units (s.e. = 0.57). Mortality rates of the singles were highly correlated with that of twins (r = 0.86, P<0.001), with a 1% unit change in death rate of singles being associated with a 2.5% (s.e. = 0.41) unit change for twins. Mortality rates of twins were associated with mean cotyledon diameter measured in mid-pregnancy (r = -0.48, n = 13, P<0. l0), and mean umbilical resistance to blood flow (r = 0.78, n = 9, P<0.02). Growth from birth to weaning of single-born lambs was associated with the mean liveweight of the flock in mid-pregnancy (r = 0.72, P<0 .001). Clean fleece weight and mean fibre diameter of the fleeces from single.bearing and rearing ewes were correlated with mean ewe liveweight in mid-pregnancy (r = 0.56, P<0.05; r = 0.70, P<0.01; respectively). Staple strength was correlated with mean ewe liveweight at marking for both single and twin producing ewes (r = 0.72, n = 18, P<0.01; r = 0.74, n = 9, P<0.05; respectively). It was concluded that liveweight of the ewe in mid-pregnancy, which represents the sum of starting liveweight and liveweight change, is the most important single and practical criterion that can be used by a farmer to set the goals for nutritional management of the flock over pregnancy to improve lamb survival.

scholarly journals Improving the nutrition of Merino ewes during pregnancy increases the fleece weight and reduces the fibre diameter of their progeny's wool during their lifetime and these effects can be predicted from the ewe's liveweight profile

2011 ◽  
Vol 51 (9) ◽  
pp. 794 ◽  
Author(s):  
A. N. Thompson ◽  
M. B. Ferguson ◽  
D. J. Gordon ◽  
G. A. Kearney ◽  
C. M. Oldham ◽  
...  
Keyword(s):  
Western Australia ◽  
Opposite Effect ◽  
Fibre Diameter ◽  
Late Pregnancy ◽  
Wool Production ◽  
Wide Range ◽  
Condition Score ◽  
Pregnancy And Lactation ◽  
Fleece Weight ◽  
Poor Nutrition

Nutrition of ewes during pregnancy can have permanent impacts on the production potential of their progeny. The hypothesis tested in the experiments reported in this paper was that improving the nutrition of Merino ewes during pregnancy and lactation increases the fleece weight and reduces the fibre diameter of their progeny’s wool during their lifetime. In addition, that these effects on the progeny’s wool production can be predicted from the ewe’s liveweight profile. At sites in Victoria and Western Australia in each of 2 years, a wide range in the liveweight and condition score profiles of Merino ewes was generated by varying the amount of supplements fed from joining to Day 100 of pregnancy and the amount of feed on offer grazed from Day 100 to weaning. The site in Victoria was based on perennial pastures and included both single- and twin-bearing ewes whereas the site in Western Australia was based on annual pastures and included single-bearing ewes only. The production and characteristics of wool from the progeny were measured until 51 months of age at the site in Victoria and 33 months of age at the site in Western Australia. The nutritional treatments and the resulting changes in ewe liveweight had significant impacts on the fleece weight and to a lesser extent the fibre diameter of wool produced by their progeny, but there were no consistent effects on other characteristics of progeny fleece wool. The fleece weight of the progeny was related to the liveweight change during pregnancy of their mothers (P < 0.05) and the relationships were similar for the two experiments at each site. At the site in Victoria, a loss of 10 kg in ewe liveweight between joining and Day 100 of pregnancy reduced fleece weight by ~0.2 kg at each shearing until 51 months of age whereas gaining 10 kg from Day 100 of pregnancy to lambing had the opposite effect. The effect of changes in ewe liveweight during late pregnancy on the fleece weight of their progeny at each shearing was of similar magnitude at the site in Western Australia. When evident, the effect of the ewe liveweight profile on the fibre diameter of progeny wool was opposite to the effect on clean fleece weight and the effect of poor nutrition in early to mid pregnancy could be completely overcome by improving nutrition during late pregnancy. Twin-born and reared progeny produced ~0.3 kg less clean wool at each shearing (P < 0.001) that was 0.3-μm broader (P < 0.001) than that from single-born progeny at the site in Victoria. However, the effects of varying ewe nutrition and ewe liveweight change during pregnancy on fleece weight and fibre diameter of progeny wool were similar (P > 0.05) for both single- and twin-born or reared progeny. Overall, these results supported our hypothesis and it is clear that the nutritional management of Merino ewes during pregnancy is important for optimal wool production from their progeny during their lifetime.

scholarly journals The wool production and reproduction of Merino ewes can be predicted from changes in liveweight during pregnancy and lactation

2011 ◽  
Vol 51 (9) ◽  
pp. 763 ◽  
Author(s):  
M. B. Ferguson ◽  
A. N. Thompson ◽  
D. J. Gordon ◽  
M. W. Hyder ◽  
G. A. Kearney ◽  
...  
Keyword(s):  
Fibre Diameter ◽  
Late Pregnancy ◽  
Reproductive Rate ◽  
Breeding Cycle ◽  
Wool Production ◽  
Condition Score ◽  
Pregnancy And Lactation ◽  
Influence Of Food ◽  
Staple Strength ◽  
Fleece Weight

Defining the nature of the relationship between change in liveweight throughout a breeding cycle and ewe wool production and reproduction would be useful for developing management guidelines for Merino ewes. In this paper we tested the hypotheses that (1) feed on offer has variable effects on liveweight profiles of individual ewes; and (2) liveweight profiles of individual ewes can be used to predict their fleece wool production and reproductive performance. At sites in Victoria and Western Australia in 2001 and 2002, pregnant Merino ewes were exposed to 10 nutritional treatments. In each of the four experiments, ewes in average condition score 3 at artificial insemination were fed to achieve either maintenance or loss of a condition score over the first 100 days of pregnancy before grazing one of five levels of feed on offer between Day 100 and lamb weaning. Across all four experiments, the average difference in ewe liveweight between extreme treatments was: 7.0 kg (range 4.7–8.7 kg) at Day 100 of pregnancy; 11.9 kg (range 4.9–17.8 kg) at lambing; and by weaning was 13.9 kg (range 8.8–22.7 kg). Liveweight at joining and liveweight change during pregnancy and lactation of individual Merino ewes were significantly related to their clean fleece weight, fibre diameter and staple length and thus the second hypothesis was supported. Heavier ewes at joining produced more wool that was longer and broader and this effect was consistent across both sites and years. A 10-kg loss in ewe liveweight between joining and mid pregnancy, mid pregnancy and lambing or during lactation reduced clean fleece weight by 0.4–0.7 kg and fibre diameter by 0.5–1.4 um. At the Victorian site, where ewes were shorn in summer, a loss of 10 kg in liveweight between joining and Day 100 of pregnancy reduced staple strength by 5 N/ktex. As expected the influence of food on offer on changes in ewe liveweight was different between years and sites and between late pregnancy and lactation due to a complex group of pasture and animal factors. Therefore, managing changes in ewe liveweight itself rather than feed on offer will achieve more predictable outcomes. A higher liveweight at joining resulted in a predictable improvement in ewe reproductive rate and liveweight at joining was more important than the liveweight profile leading up to joining. This paper has shown that it is possible to predict the differences in wool production and reproductive rate of flocks of Merino ewes if ewe liveweight records at key times are known.

scholarly journals Genetic parameters for yearling wool production, wool quality and bodyweight traits in fine wool Merino sheep

2008 ◽  
Vol 48 (9) ◽  
pp. 1168 ◽  
Author(s):  
A. A. Swan ◽  
I. W. Purvis ◽  
L. R. Piper
Keyword(s):  
Genetic Parameters ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Merino Sheep ◽  
Wool Quality ◽  
Staple Strength ◽  
Fleece Weight ◽  
Highly Correlated ◽  
Genetic Evaluations ◽  
Trait Groups

Genetic parameters were estimated for traits measured in the first year of production in a multi-bloodline flock of fine wool Merino sheep. Between 5025 and 9271 animals were measured, depending on the trait, and these animals were the progeny of up to 430 sires. Heritability estimates for fleece weight traits ranged from 0.37 to 0.49, while estimates for five wool quality traits ranged from 0.34 for staple strength to 0.66 for mean fibre diameter. For bodyweight, the heritability estimated at weaning was 0.20, and at the yearling age was 0.51. Maternal genetic effects were significant for fleece weight and bodyweight traits and were highly correlated between these trait groups, indicating that these effects are determined by similar groups of genes in both trait groups. While most genetic correlation estimates were either favourable or neutral, there were economically antagonistic correlations between fleece weight and mean fibre diameter, ranging from 0.15 to 0.30, and between mean fibre diameter and staple strength (0.26). Overall, the heritabilities and genetic correlations estimated in this fine wool population were similar to estimates from other strains, indicating that outcomes from selection programs will be similar across strains and that fine wool sheep can be included in across flock genetic evaluations with other strains.

The influence of selection and plane of nutrition on the components of fleece weight in Merino sheep

1958 ◽  
Vol 9 (6) ◽  
pp. 802 ◽  
Author(s):  
RB Dun
Keyword(s):  
Fibre Diameter ◽  
Fibre Length ◽  
Small Contribution ◽  
Cross Sectional ◽  
Single Character ◽  
The Mean ◽  
Low Levels ◽  
The Difference ◽  
Fleece Weight ◽  
High Level

The components of clean fleece weight were examined in five experimental flocks of medium-wool Peppin Merinos. Four single-character selection groups – clean fleece weight plus, clean fleece weight minus, crimps per inch plus, and crimps per inch minus – were examined by measuring fleece production in 18-month-old ewe progeny. Measurements were also made on progeny from the "nucleus" flock, which was selected for clean fleece weight with subsidiary selection for crimps per inch and against fold score. Data were collected in 1952 and 1954. The 1954 figures were obtained from a nutrition experiment in which sheep mere grown from weaning to 18 months on a high and on a low plane of nutrition. The mean measurements of the components of clean fleece weight (W) were compared between flocks using the "percentage deviation" technique. Four comparisons were made: (1) Nucleus/Fleece minus; (2) Fleece plus/Fleece minus; (3) Crimps minus/Crimps plus; (4) high nutritional plane/low nutritional plane. In comparisons (1) , (2), and (3), difference in weight of wool per unit area of skin (w) accounted for nearly all the difference in W. Body weight (S) made a small contribution while difference in fold score (R) was negligible. Fibre density (N) accounted for +86 per cent., and fibre cross-sectional area (A) for –28 per cent., of the difference in W in comparison (1). In comparison (2) the figures were N +47 per cent., A +21 per cent., while the figures for comparison (3) were N –26 per cent., A +121 per cent. The increase in fleece weight was invariably accompanied by a decrease in crimps per inch. In all three comparisons primary density (P) was the major cause of change in N. Fibre length (L) made a uniform contribution of approximately +15 per cent. in the three comparisons.The relative importance of the components of fleece weight was similar at both high and low levels of nutrition.The effect of a high level of nutrition was to produce large increases in A, L, and S. The increase in S was compensated by an equal decrease in P. The increase in fibre diameter was not associated with any change in crimps per inch.

Wool prices and sheep breeding objectives - a historical perspective

1994 ◽  
Vol 45 (8) ◽  
pp. 1671 ◽  
Author(s):  
DJ Cottle
Keyword(s):  
Important Determinant ◽  
Moving Average ◽  
Fibre Diameter ◽  
Percentage Increase ◽  
Sire Evaluation ◽  
Selection Indices ◽  
Breeding Objectives ◽  
Fibre Fineness ◽  
The Mean ◽  
Fleece Weight

An analysis of weekly wool prices for different fibre diameter market indicators from 1950 to 1993 was conducted to determine appropriate economic values for the calculation of sheep selection indices. An important determinant of breeding objectives and selection indices is the percentage increase in the value of wool for each 1 8m reduction in fibre diameter, termed index percentage (IP). From 1950 to 1981 the appropriate IP value for fine (20 8m), medium (21 8m) and strong (23 8m) wool Merinos was 5%. From 1981 to 1993 the mean weekly IP values for fine, medium and strong wool Merinos were about 20, 15 and 8% respectively. The 5 year moving average IP values in 1993 for fine, medium and strong wool Merinos were 25, 20 and 8% respectively. The distributions of weekly wool prices and IP values are not normal and are positively skewed. Therefore, a safer, more conservative approach is to calculate the median weekly IP values for any period or to use median weekly wool prices to calculate IP values. The median weekly IP values for 1981-1993 were 20, 11 and 8% for fine, medium and strong Merino wools respectively. Thus recently there has been a larger relative premium for fibre fineness which could be a permanent trend. Selection efficiencies for clean fleece weight and fibre diameter in fine and strong wool Merinos are predicted to be at least 90% when 10% and 5% indices are used respectively. Selection efficiency in medium wool Merinos when a 5% index is used is only 79% if the 'true' IP is 15%, or 90% if the 'true' IP is 10%. The 10% and 5% indices are currently calculated and made available to the ram owners who participate respectively in the N.S.W. Merino fine and medium wool sire evaluation schemes. It is suggested that there is a case for using indices with higher fibre diameter premiums (i.e. 20% and 10% respectively), than those currently provided in the fine and medium wool schemes.

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.

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.

Fibre diameter and staple strength of sheep selected for divergent clean fleece weight when subjected to an increase in intake or an increase in intake and diet change

2005 ◽  
Vol 56 (2) ◽  
pp. 195 ◽  
Author(s):  
M. A. Friend ◽  
G. E. Robards
Keyword(s):  
Growth Rate ◽  
Stepwise Regression ◽  
Fibre Diameter ◽  
Dietary Treatment ◽  
Diet Change ◽  
Wool Growth ◽  
Ad Libitum ◽  
Staple Strength ◽  
Fleece Weight ◽  
Ad Libitum Feeding

Merino wethers with a high (fleece plus, Fl+) or low (fleece minus, Fl–) potential for wool growth were offered a restricted intake of either oat grain or lucerne chaff for 8 weeks followed by ad libitum lucerne chaff for 4 weeks. The Fl– sheep that were fed oats then lucerne had a lower (P < 0.05) intake during the first 2 weeks of ad libitum feeding than all other groups. Staple strength of Fl+ sheep (37.5 ± 2.2 N/ktex) was less (P < 0.05) than that of Fl– sheep (44.5 ± 2.4 N/ktex), and dietary treatment did not significantly affect staple strength. Wool growth rate was unaffected by dietary treatment, but was greater (P < 0.001) for Fl+ (6.4 ± 0.2 µg/mm2.day) than for Fl– (4.0 ± 0.2 µg/mm2.day) sheep. Along-fibre variation in diameter was greater (P < 0.001) in Fl+ (15.6 ± 0.5%) than in Fl– (9.9 ± 0.5%) sheep. Between-fibre variation in diameter was greater (P < 0.001) in Fl+ (16.5 ± 0.5%) than in Fl– (13.2 ± 0.5%) sheep, and between-fibre variation in diameter was affected (P < 0.05) by dietary treatment in Fl+ sheep. Staple strength was significantly correlated (P < 0.05) with along-fibre variation in diameter (r = –0.48), and stepwise regression analysis indicated that along-fibre variation in diameter, wool growth rate during early restricted feeding, and minimum fibre diameter explained 63% of the variance in staple strength. The results are discussed in relation to the lower staple strength of Fl+ sheep.

Seasonal variation in fibre diameter and length in wool of grazing Merino sheep with low or high staple strength

1999 ◽  
Vol 39 (5) ◽  
pp. 507 ◽  
Author(s):  
A. C. Schlink ◽  
G. Mata ◽  
J. M. Lea ◽  
A. J. M. Ritchie
Keyword(s):  
Fibre Diameter ◽  
Fibre Length ◽  
Subterranean Clover ◽  
Experimental Period ◽  
Strength Group ◽  
Pooled Data ◽  
Length Growth ◽  
Fibre Growth ◽  
Staple Strength ◽  
Highly Correlated

The associations between fibre growth characteristics and wool staple strength were investigated in groups (n = 10) of Merino wethers with either low or high staple strength. Sheep grazed together on pastures based on subterranean clover and annual rye grass for about 13 months. The sheep were weighed and injected intradermally with [35 S]-cysteine at about 14-day intervals. Mid-side patches were harvested and dye bands placed in the wool at about 28-day intervals. Patch clean wool growth, pasture digestible dry matter/ha and pasture crude protein/ha had similar seasonal amplitudes of production (287, 286 and 267% of respective minimum). These were significantly higher than the seasonal amplitude in liveweight (24.5%). The seasonal amplitude in fibre diameter was significantly greater than that for rate of fibre elongation (71.4 and 41.4% respectively). This seasonality in fibre length and diameter resulted in statistically significant seasonal fluctuations in the ratio of fibre length growth to fibre diameter. Fortnightly variability in fibre diameter was not significantly related to variability in fibre length growth rate between sheep for individual time periods. However, for the pooled data over the experimental period a statistically significant relationship (R2 = 0.13, P<0.01) was improved with the addition of parameters for sampling time and staple strength group. Staple strengths for the low and high staple strength groups were 25.6 and 32.8 N/ktex respectively (P = 0.057). There were no significant differences between the staple strength groups in seasonal change in liveweight, wool production or fibre parameters measured in this study but the low staple strength group had longer fibres. Staple strength was most highly correlated with mid-side fibre diameter coefficient of variation (R2 = 0.50) followed by seasonal amplitude in liveweight.

scholarly journals Managing the nutrition of twin-bearing ewes during pregnancy using Lifetimewool recommendations increases production of twin lambs

2011 ◽  
Vol 51 (9) ◽  
pp. 813 ◽  
Author(s):  
J. E. Hocking Edwards ◽  
K. J. Copping ◽  
A. N. Thompson
Keyword(s):  
Body Condition ◽  
Management Practices ◽  
Body Condition Score ◽  
Survival Rates ◽  
Fibre Diameter ◽  
South Australia ◽  
The Body ◽  
Condition Score ◽  
Pregnancy And Lactation ◽  
Staple Strength

The effect on ewe and lamb production by differential management of single- and twin-bearing Merino ewes during pregnancy and lactation was examined. The hypothesis that the survival and productivity of single- and twin-born progeny is not affected by differential management of single- and twin-bearing ewes was tested. To test this hypothesis, two ewe flocks were monitored on a commercial property in the south-east of South Australia. The body condition score of one flock of ewes was managed according to Lifetimewool recommendations for southern Australian (Lifetimewool flock; n = 464). Lifetimewool recommendations are that body condition score should be 3.0 at mating and then allowed to decline to an average of 2.7, which is maintained until lambing. Twin- and single-bearing ewes were managed as separate mobs after pregnancy scanning to meet their energy requirements. The second flock was managed similarly to the commercial ewe flock and was representative of ewe management practices in the region (normal-practice flock; n = 464). At lambing, the condition score of the Lifetimewool flock was 0.7 condition scores units greater than the normal-practice flock. Ewe clean fleece weight and fibre diameter were greater in the Lifetimewool flock and their lambs had higher survival rates to weaning. Over three shearings, progeny from Lifetimewool ewe flocks produced more clean wool (P < 0.0001) but there was no consistent effect on fibre diameter, staple length or staple strength. Twin-born lambs from ewes managed to Lifetimewool guidelines had a similar liveweight and produced similar quantity and quality of wool to single-born lambs managed to Lifetimewool guidelines, but still suffered higher rates of mortality to weaning. This suggests that it is possible to manage ewes pregnant with twins to ensure that their surviving progeny perform at a level similar to single-born progeny managed under similar targets.

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