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 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 On-farm paddock-scale comparisons across southern Australia confirm that increasing the nutrition of Merino ewes improves their production and the lifetime performance of their progeny

2011 ◽  
Vol 51 (9) ◽  
pp. 805 ◽  
Author(s):  
R. Behrendt ◽  
A. J. van Burgel ◽  
A. Bailey ◽  
P. Barber ◽  
M. Curnow ◽  
...  
Keyword(s):  
Fibre Diameter ◽  
South Australia ◽  
Final Analysis ◽  
Reproductive Rate ◽  
Wool Production ◽  
Condition Score ◽  
Pregnancy And Lactation ◽  
Fleece Weight ◽  
Fat Score ◽  
Progeny Performance

Experiments conducted by Lifetimewool at plot-scale have shown that differences in the maternal liveweight during pregnancy and lactation (liveweight profiles) of individual Merino ewes influences their wool production and reproductive rate as well as the birthweight, survival, weaning weight and lifetime wool production of their lambs in a predictable manner. This study determined whether these impacts of nutrition of the ewe on ewe and progeny performance are measurable on commercial properties across southern Australia at a paddock-scale where ewes were aggregated into flocks with a greater spread of the date of conception and where the liveweight profile of the flocks were managed based on random samples of 100 ewes and liveweight was uncorrected for fleece weight or conceptus. Eighteen paddock-scale experiments at 15 sites were conducted in cooperation with wool producers across Victoria, Western Australia, New South Wales, South Australia, and Tasmania. Each co-operator joined up to 1000 mixed aged adult Merino ewes. The flock was scanned using ultrasound at Day 50 from the start of joining to identify those ewes that conceived during the first 21 days of joining. These ewes were then split at random into two treatments and fed to achieve a target difference in liveweight of 10 kg or ~1 condition score/fat score at lambing. The production of ewes during their year of pregnancy and following their next joining was measured as was the performance of their progeny up to their third shearing. Only the 13 paddock-scale experiments that achieved a difference in liveweight profile at lambing of at least 4 kg were included in the final analysis. In these 13 experiments, increasing the nutrition of Merino ewes during pregnancy clearly increased the clean fleece weight and fibre diameter in ewes and the survival and lifetime wool production of their lambs. In most cases the size of the effect was not significantly different to that predicted by the relationship derived using individual liveweight profiles in the plot-scale experiments. This confirms that managing average ewe liveweight or condition score/fat score profile through better nutrition will lead to predictable increases in the performance of ewes and their progeny performance under commercial conditions and validates the use of the plot-scale relationships in economic analyses.

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.

Lambing performances and wool production of maiden and adult Merino ewes fed different amounts of lupin seed in mid-pregnancy

1992 ◽  
Vol 43 (2) ◽  
pp. 339 ◽  
Author(s):  
RW Kelly ◽  
EJ Speijers ◽  
IG Ralph ◽  
JP Newnham
Keyword(s):  
Birth Weight ◽  
Crude Protein ◽  
Fibre Diameter ◽  
Late Pregnancy ◽  
Maternal Plasma ◽  
Waveform Analysis ◽  
Wool Production ◽  
Glucose Levels ◽  
Lupin Seed ◽  
Pregnancy And Lactation

Maiden (1.5 years old, 42 kg) and adult (4-5 years old, 55-58 kg) Merino ewes were divided into 15 groups of 30 on the basis of ovulation rate (three classes of ewe: maiden = 1, adult = 1 or 2) and fed lupin seed (91% digestible, 33% crude protein) three times per week at rates equivalent to 0, 100, 200, 300, or 400 g head-1 day-1 from day 28 to day 108 of pregnancy (17 December to 6 March). Thereafter the ewes were fed at the same rate (400-500 g head-1 day-1 of lupins, ad libitum oaten hay) until two weeks post lambing. They were grazed on two hectare plots from day 22 of pregnancy until two weeks after lambing; the plots had 1.3 tomes dry matter/ha (54% digestible, 11% crude protein) at the start of grazing. The differential feeding induced changes in liveweight and condition score during mid-pregnancy ranging across the ewe classifications from 8.4 to +5.0 kg and -1.6 to +1.3 units, respectively. In late pregnancy and lactation there were compensatory changes in the ewes, so that at 12 weeks post-lambing the difference between the animals from the mid-pregnancy feeding treatments had been reduced to less than 2 kg. There was a significant relationship (linear P < 0.001) between lamb birth weight and rate of lupin feeding during mid-pregnancy. For every 0.1 kg head-' day-' of lupins fed, lamb birth weight increased by 0.11 kg. There was no significant effect of class of ewe on this relationship. Maternal plasma glucose levels at about day 100 of pregnancy increased with rate of lupin feeding (interaction between class of ewe and feeding treatment P < 0.01). Ultrasound measurements of cotyledon diameters were greater (P < 0.001), and resistance to maternal placental blood flow less (assessed by Doppler arterial waveform analysis, interaction between class of ewe and feeding treatment P < 0.05) at about day 100 of pregnancy in ewes fed 400 g head-1 day-1 of lupins compared with unfed ewes. These findings indicated that in the unfed ewes there was a reduced nutrient supply to the fetus from reduced glucose availability, smaller placentas and less expansion of the placental vasculature. Growth of the lambs to four weeks of age increased with rate of lupin feeding in mid-pregnancy (quadratic P < 0.05), although the actual differences in weight at four weeks of age were small (<1 kg). Annual wool production from the ewes was significantly affected by the differential feeding during mid-pregnancy, with clean fleece weight (linear P < 0.01), staple length (linear P < 0.01) and strength (linear P < 0.001) increasing with increased rate of lupin feeding, and the position of break shifted from the period of pregnancy to after lambing (quadratic P < 0.01). Mean fibre diameter was not significantly affected by any treatment. It was concluded that the ewes at greatest risk from underfeeding in mid-pregnancy, in terms of lamb and wool production, were maiden ewes and adult ewes bearing twins.

Grazing management of reproducing ewes affects staple strength

2000 ◽  
Vol 40 (6) ◽  
pp. 783 ◽  
Author(s):  
S. M. Robertson ◽  
G. E. Robards ◽  
E. C. Wolfe
Keyword(s):  
Fibre Diameter ◽  
Late Pregnancy ◽  
Staple Fibre ◽  
Grazing Management ◽  
Nutritional Management ◽  
Early Lactation ◽  
Wool Growth ◽  
Pregnancy And Lactation ◽  
Staple Strength ◽  
Lamb Growth

A grazing study was conducted on irrigated pastures to assess the influence of manipulating the availability of green pasture at different stages of pregnancy and lactation on the staple strength of broad-wool Merino ewes lambing in July. Sheep subjected to different treatments produced wool ranging between 14 and 48 N/ktex for single-rearing and 22 and 53 N/ktex for non-lambing ewes. Single-bearing/rearing ewes produced wool of strength +4.7 (P>0.05) to –23 N/ktex (P<0.001) in comparison with non-lambing ewes. Reproduction was associated with a reduction in staple strength of 51, 24 and 9% for ewes grazed throughout the experiment at low, medium and high pasture levels, respectively. A staple strength greater than 40 N/ktex was achieved in single-rearing ewes which grazed high pasture mass throughout pregnancy and lactation, during late pregnancy and early lactation, or during mid-pregnancy. Single-rearing ewes, which grazed low pasture biomass throughout either mid, late or all of pregnancy, or during lactation, produced wool with staple strength less than 30 N/ktex. In comparison to grazing the medium pasture allowance throughout the experiment, manipulation of pasture availability had relatively small effects on lamb growth and average fleece measurements, compared with the effects on staple strength. The exception was ewes grazing only the low pasture allowance. The interaction between reproduction and nutritional management influenced staple strength by altering the minimum fibre diameter and the uniformity of along-staple fibre diameter and rate of wool growth. It was concluded that managing pasture availability to promote a uniform along-staple fibre diameter or rate of wool growth can prevent reductions in staple strength associated with reproduction.

Effects on wool production during pregnancy and lactation of twice daily abomasal supplementation with casein or methionine and cystine

1978 ◽  
Vol 18 (90) ◽  
pp. 52 ◽  
Author(s):  
AJ Williams ◽  
RN Tyrrell ◽  
AR Gilmour
Keyword(s):  
Amino Acids ◽  
Fibre Diameter ◽  
Late Pregnancy ◽  
Similar Response ◽  
Early Lactation ◽  
Wool Production ◽  
Wool Growth ◽  
Pregnancy And Lactation ◽  
Sulphur Amino Acids ◽  
Sorghum Grain

The responses in wool production of Merino ewes to abomasal supplements of casein (56 g day-1) and of a mixture of methionine and cystine were measured during late pregnancy and early lactation. The mixed supplement provided equal quantities of the sulphur amino acids as the casein. The ewes were offered sufficient quantities of a diet of sorghum grain/lucerne hay (in the ratio 7 : 3 by weight) to maintain maternal liveweight. During the final four weeks of pregnancy and the first six weeks of lactation, the cassin supplement increased wool growth (826 vs. 639 g cm-2 day-1). A similar response was observed for fibre diameter (1 9.7 vs. 18.5 pm : P < 0.05). Wool production and fibre diameter did not differ between the ewes supplemented with methionine and cystine and the control ewes during this same period. The ewes supplemented with methionine and cystine produced wool with the greatest sulphur content, and this trait was least in the wool from the control ewes (3.84 vs. 3.64 vs. 3.49: P < 0.05). We concluded that the availability of the sulphur amino acids was not primarily limiting wool production in pregnant/lactating ewes.

Reproduction effects on annual fleece production, liveweight and body condition of grazing Merino ewes

2000 ◽  
Vol 40 (7) ◽  
pp. 931 ◽  
Author(s):  
C. M. Waters ◽  
K. A. Coelli ◽  
G. J. Lee ◽  
K. D. Atkins
Keyword(s):  
Body Condition ◽  
Reproductive Cycle ◽  
Fibre Diameter ◽  
Production Capacity ◽  
Major Effect ◽  
Wool Production ◽  
Merino Wool ◽  
Condition Score ◽  
Fleece Weight ◽  
Reproductive Cycles

This study sought to confirm the long-term consequences of current and previous reproductive cycles on liveweight, body condition and wool growth over the lifetime of Merino ewes (2–6 years of age). Liveweights and body condition scores at 4 stages of the reproductive cycle, and annual fleece weights (greasy and clean), fibre diameter and yield were analysed to determine the effects of the previous and current reproductive performance (birth-type or rearing-type categories) using records from about 3300 Merino ewes collected between 1977 and 1989. The major effect of current reproduction on liveweight and wool production was associated with fertility, although both birth and rearing types also contributed. Ewes that lambed in the current year weighed 5.2 kg less at weaning and grew 0.4 kg less clean wool annually than dry ewes, while ewes that reared a lamb to weaning weighed 4.3 kg less than ewes that lost their lamb(s). The effects on condition score followed those of liveweight. The effects of previous reproduction on liveweights and condition scores were large and, although diminishing with time, lasted for at least 10 months, whereas any effects on annual fleece weight and mean fibre diameter were small. The results suggest that many ewes may enter the next reproductive year before recovering from the reduction in either liveweight or body condition associated with the previous reproductive cycle. Since Merino ewes are required to produce both wool and replacement sheep, the changes in a ewe’s production capacity associated with reproduction are important to Merino wool production enterprises as their profitability may be influenced.

Effects of stocking rate in spring on liveweight and wool production of sheep grazing annual pastures

1994 ◽  
Vol 45 (2) ◽  
pp. 367 ◽  
Author(s):  
AN Thompson ◽  
PT Doyle ◽  
M Grimm
Keyword(s):  
Fibre Diameter ◽  
Stocking Rate ◽  
Wool Production ◽  
Wool Growth ◽  
Linear Relationships ◽  
Condition Score ◽  
Grazing Period ◽  
Staple Strength ◽  
Stocking Rates ◽  
Staple Length

Two experiments examined the effects of different stocking rates in spring, and hence the availability of annual pastures, on changes in liveweight and wool production in Merino wethers (Experiments 1 and 2 respectively: age 5 and 2+-year-old; liveweight 63.8 � 0.64 (s.e.m.) kg and 43.8 � 0.34 kg; condition score 3.9% 0.14 and 3.l � 0-08). In Experiment 1, stocking rates were 8, 16, 24, 32 and 40 sheep/ha from 8 August, 1989 f9r 122 days; Experiment 2 involved an additional stocking rate of 48 sheep/ha from 23 August, 1990 for 98 days. Feed on offer (FOO kg DM/ha) declined (P < 0.01) linearly as stocking rate increased. Stocking rate and initial FOO (ranging between 1100 and 7000 kg DM/ha) had no significant effects on pasture growth rate (PGR) through most of spring. Late in spring, increased stocking rates resulted in greater (P < 0.05) PGR. The total amount of pasture produced in the grazing period was not significantly affected by stocking rate (Expt 1, 7530 to 8200 kg DM/ha; Expt 2, 6390 to 6860 kg DM/ha). The relationships between liveweight change (LWC) or wool growth rates (WGR) and FO, during the period until pasture wilting at the lowest stocking rate (83 days in Expt 1; 76 days in Expt 2), were described by Mitscherlich equations. More than 74% of the variation in LWC or WGR was explained by differences in green FOO. In Expts 1 and 2 respectively, more than 90% of the maximum liveweight gain (66 and 192 g/day) was achieved at a FOO of 4000 or 3000 kg DM/ha, and sheep maintained weight at 2000 or 1000 kg DM/ha. More than 90% of the maximum WGR (22.3 and 19.0 g/day) was achieved at a FOO of 3000 or 2000 kg DM/ha. More than 70% of the variation in WGR was explained by LWC in both experiments. The slopes of the linear relationships were 0.047 g wool/g LWC in Expt 1, and 0.024 g wool/g LWC in Expt 2. At liveweight maintenance, sheep produced 15% less (Expt 1) or 25% less (Expt 2) wool than those grazed under conditions which allowed maximum rates of liveweight gain. Fibre diameter (FD) and length of wool grown were affected in the same manner as WGR by increases in FOO and hence LWC. In Expts 1 and 2 respectively, total clean wool weights were reduced by 17 and 9 g, mean FD by 0.05 and 0.02 microns and staple length by 0.35 and 0.13 mm, for each increase of one sheep/ha during the spring treatment periods. The effects of stocking rate in spring on annual wool production, mean FD and staple length were described by linear (P < 0.05 to P < 0.01) relationships. Standard deviation of midside FD (Expt 2), staple strength and position of break (both experiments) did not change significantly with stocking rate. These results indicate that grazing to a lower FOO during spring can be used to manipulate the amount and characteristics of wool produced by Merino wethers grazing annual pastures in Mediterranean climates with 600-700 mm rainfall.

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.

Changes in plasma amino acid patterns and wool growth during late pregnancy and early lactation in the ewe

1993 ◽  
Vol 44 (5) ◽  
pp. 945 ◽  
Author(s):  
DG Masters ◽  
CA Stewart ◽  
PJ Connell
Keyword(s):  
Amino Acids ◽  
Fibre Diameter ◽  
Late Pregnancy ◽  
Essential Amino Acids ◽  
Early Lactation ◽  
Wool Growth ◽  
Pregnancy And Lactation ◽  
Staple Strength ◽  
Animal House ◽  
Limiting Amino Acids

Pregnancy and lactation result in depressed growth, fibre diameter and tensile strength of wool. Competition for nutrients between wool follicles, maternal tissues and the foetus may cause these changes. Changes in the concentrations of individual free amino acids in plasma, during late pregnancy, were used as indicators of limiting amino acids in this experiment. A group of pregnant ewes was maintained in the animal house during late pregnancy and early lactation and measurements made on amino acids in plasma. Liveweight, wool growth and quality characteristics and sulfur in wool were also measured. Comparisons were made between the different time periods in pregnancy and lactation and between the reproducing ewes and a group of non-reproducing ewes maintained under the same conditions. During the last 3 weeks of pregnancy, there was a 31% decline in the concentration of the total, free essential amino acids in plasma. There was also a significant decline in the concentration of arginine (60%), lysine (55%) and threonine (48%). The concentrations of these amino acids increased during the first 3 weeks of lactation. There was no change in concentration of methionine or cystine. Wool growth rate was lowest in the last 3 weeks of pregnancy and the reproducing ewes had significantly lower wool growth, fibre diameter, staple strength and sulfur in wool than the non-reproducing ewes. The results indicate that a lack of the sulfur-containing amino acids is unlikely to be limiting, but a lack of arginine, lysine or threonine may be limiting wool growth and protein deposition in late pregnancy.

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