Subclinical selenium insufficiency. 1. Selenium status and the response in liveweight and wool production of grazing ewes supplemented with selenium

1991 ◽  
Vol 31 (1) ◽  
pp. 25 ◽  
Author(s):  
JP Langlands ◽  
GE Donald ◽  
JE Bowles ◽  
AJ Smith
Keyword(s):  
Reproductive Performance ◽  
Whole Blood ◽  
Fibre Diameter ◽  
Selenium Status ◽  
Stocking Rate ◽  
Seasonal Trends ◽  
Wool Production ◽  
Se Status

Fine wool Merino and Border Leicester x Merino ewes grazed improved pastures low in selenium (Se) for 4 years at 6.3 and 12.5 sheep/ha; half of the ewes were supplemented with Se given as an intra-ruminal pellet. Selenium status of the ewes was monitored from Se concentrations in whole blood and plasma, and wool production, fibre diameter and liveweight were recorded. The unsupplemented ewes showed no overt signs of Se insufficiency; Se status was consistently low; and Se supplementation increased wool production and fibre diameter. Selenium status was lower in unsupplemented ewes grazed at the higher stocking rate and in ewes supporting a lamb; it showed seasonal trends and was negatively correlated with rainfall. Selenium concentrations in whole blood but not in plasma were lower in Merino than in Border Leicester x Merino ewes. Data relating to reproductive performance and the productivity of the lambs are presented in accompanying reports.

Effect of time of joining and rate of stocking on the production of Corriedale ewes in southern Victoria. 3. Wool growth and the composition and availability of pasture

1975 ◽  
Vol 15 (73) ◽  
pp. 159 ◽  
Author(s):  
PA Kenney ◽  
IF Davis
Keyword(s):  
Fibre Diameter ◽  
Late Pregnancy ◽  
The Other ◽  
Early Lactation ◽  
Stocking Rate ◽  
Wool Production ◽  
Wool Growth ◽  
The Mean ◽  
Brome Grass ◽  
Stocking Rates

A study was made during a three year period (1 968-1 970) of wool production by a flock of 540 ewes grazing annual pasture at Werribee, Victoria. The ewes were stocked at three rates (5, 7 1/2 and 10 ewes ha-1) and lambed between July 6 and August 20 or between September 10 and October 29 each year. Fibre diameter and length of wool samples were measured in 1968, 1969 and 1970 ; in 1970 growth of greasy wool was calculated from staples of dye-banded wool. Wool growth was reduced in all ewes during late pregnancy and early lactation but was not affected during late lactation in ewes lambing in September. The proportion of tender fleeces from all ewes was greater in 1970 and the weight of fleeces from only those ewes bearing single lambs was less in all years for ewes lambing in July than for ewes lambing in September. More ewes were barren and fewer ewes had twins in July and consequently the mean fleece weights of all ewes from both groups were similar. Fleeces from ewes stocked at 10 ha-1 were lighter, shorter and finer than fleeces from ewes stocked at 5 and 7 1/2 ha-1, but the proportion of tender fleeces did not differ between the groups. Wool production of ewes stocked at 5 and 7 1/2 ha-1 increased from 1968 to 1970, whereas that of ewes at 10 ha-1 did not. This was associated with differences in pasture availability and composition. At 10 ewes ha-1 less pasture was present in winter and spring in 1970 than in 1968, whereas at the other stocking rates it was greater. In 1970 the density of weeds in autumn was greater and in spring more silver grass (Vulpia spp.) and less brome grass (Bromus spp.) was available at the high stocking rate.

Subclinical selenium insufficiency. 2. The response in reproductive performance of grazing ewes supplemented with selenium

1991 ◽  
Vol 31 (1) ◽  
pp. 33 ◽  
Author(s):  
JP Langlands ◽  
GE Donald ◽  
JE Bowles ◽  
AJ Smith
Keyword(s):  
Muscular Dystrophy ◽  
Litter Size ◽  
Reproductive Performance ◽  
Stocking Rate ◽  
Se Status

Merino and Border Leicester x Merino ewes grazed improved pastures at 6.3 or 12.5 ewes/ha for 4 years and were supplemented or not supplemented with intra-ruminal selenium (Se) pellets. The Merino and crossbred ewes were mated to Merino and Dorset Horn rams, respectively, and various measures of reproductive performance were recorded. Two cases of muscular dystrophy were observed in 2-3-day-old lambs, but the incidence of oestrus and fertility was not affected by differences in stocking rate, genotype or Se supplementation. Fecundity was higher in crossbreds than Merinos (1.64 v. 1.25, P<0.001) but was not affected by stocking rate or Se status. Survival of lambs was increased (P<0.05) by Se supplementation -- at the high stocking rate (0.74 v. 0.86) but not at the low (0.84 v. 0.83), and a significant (P<0.01) genotype x litter size x Se interaction reflected greater sensitivity to Se supplementation by Merino singletons (from 0.75 to 0.95) than twins (from 0.75 to 0.69) and by crossbred twins (from 0.76 to 0.87) than singletons (from 0.89 to 0.87). Number of lambs weaned per ewe mated increased following Se supplementation from 0.81 to 1.04 at the high stocking rate, and decreased from 1.08 to 1.00 at the low; the interaction approached significance (P<0.09). It is suggested that the response to Se supplementation is sensitive to factors in addition to Se status, and such factors may explain some of the variability in responsiveness reported in the literature.

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.

The impact of rabbits on a grazing system in eastern New South Wales. 2. Sheep production

2002 ◽  
Vol 42 (7) ◽  
pp. 917 ◽  
Author(s):  
P. J. S. Fleming ◽  
J. D. Croft ◽  
H. I. Nicol
Keyword(s):  
Body Condition ◽  
Synergistic Effects ◽  
Fibre Diameter ◽  
The Body ◽  
Stocking Rate ◽  
Economic Implications ◽  
Wool Production ◽  
Sheep Production ◽  
Short Term Experiment ◽  
The Impact

Much research, time and money have been invested in the control of rabbits in Australia, yet the relationship between rabbit density and livestock production losses has not been quantified. We experimentally investigated the variations in sheep production parameters caused by 4 densities of rabbits, 0, 24, 48 and 72 rabbits/ha. Medium to strong wool merino wethers were run at a constant stocking rate in replicated plots with rabbits at 4� different densities. Sheep liveweight and body condition and wool production variables were measured over 3�years. Low to medium densities of rabbits were not found to reduce liveweights of wethers, whereas wethers run with the high density of rabbits were significantly lighter. The presence of rabbits reduced the body condition of sympatric sheep with the lowest body condition recorded at the high rabbit density. Mean greasy fleece weights, wool yields and clean-fleece weights were significantly different between densities of rabbits. Wethers run with the high rabbit density grew less wool than the wethers run with the other 3 densities of rabbits. The cumulative gross return per ha from wool production was highest for the medium rabbit density and lowest at high rabbit density. At the conclusion of this short-term experiment, the presence of some rabbits enhanced returns from wool production because of lower fibre diameter and comparable clean-fleece weights of fleeces grown at low and medium rabbit densities. These production characteristics might have been caused by synergistic effects on pasture growth or a sheep stocking rate that was too conservative for the prevailing seasonal conditions. At high rabbit density, competition for pasture between rabbits and sheep overrode possible synergistic and understocking effects. The economic implications of the presence of rabbits on merino sheep production are discussed.

Subclinical selenium insufficiency. 3. The selenium status and productivity of lambs born to ewes supplemented with selenium

1991 ◽  
Vol 31 (1) ◽  
pp. 37 ◽  
Author(s):  
JP Langlands ◽  
GE Donald ◽  
JE Bowles ◽  
AJ Smith
Keyword(s):  
Fibre Diameter ◽  
Early Lactation ◽  
Selenium Status ◽  
Stocking Rate ◽  
Fleece Weight

Measurements were made of blood selenium (Se) concentrations and liveweights of Dorset Horn x (Border Leicester x Merino) and Merino lambs born in October to ewes which were supplemented or not supplemented with intra-ruminal Se pellets and grazed at 6.3 or 12.5 ewe/ha for 4 consecutive years. Lambs were not supplemented with Se and most observations were made between birth and weaning. In some years the Merino lambs were grazed as a single flock for a further 18 months after weaning, and liveweights and fleece characters were recorded at 10 and 22 months of age. Blood Se concentrations of lambs at birth varied with the Se treatment of their dams but were generally lower in the lamb and declined during lactation. In lambs born to unsupplemented ewes, concentrations were lower at the high stocking rate, and declined with increasing rainfall in the preceding January-June period. Selenium concentrations were reduced in twins and this was particularly evident in lambs born to supplemented ewes. Liveweights at birth, in mid-lactation and at weaning were significantly increased in lambs born to Se-supplemented and crossbred ewes, and in lambs born as singletons. The response in liveweight following Se supplementation was greater in lambs reared at the high than at the low stocking rate, and in Merino than in crossbred lambs. The response to Se supplementation was correlated with rainfall during the preceding February to July, and was greater in early lactation. Clean fleece weight at 10 months of age was increased by 9.5% and fibre diameter by 0.3 pm in lambs born to ewes which had received supplementary Se. Differences in fleece weight were not detected at 22 months.

Lucerne reduces soil moisture and increases livestock production in an area of high groundwater recharge potential

1995 ◽  
Vol 35 (2) ◽  
pp. 171 ◽  
Author(s):  
MC Crawford ◽  
MR Macfarlane
Keyword(s):  
Soil Moisture ◽  
Groundwater Recharge ◽  
Soil Water ◽  
Plant Density ◽  
Fibre Diameter ◽  
Stocking Rate ◽  
Recharge Potential ◽  
Wool Production ◽  
Hordeum Leporinum ◽  
Moisture Potential

A grazing experiment was conducted on an area with high groundwater recharge potential in northeastern Victoria from 1988 to 1992. Merino wether weaners were grazed on either lucerne (Medicago sativa) or a pasture consisting of annual species (Trifolium spp., Lolium rigidum, Vulpia bromoides, Hordeum leporinum) at 5.0, 8.75, or 12.5 wethers/ha. Lucerne pastures were rotationally grazed and annual pastures were set-stocked. Measurements included herbage mass, lucerne plant density, sheep liveweight, wool production and fibre diameter, and soil moisture potential. Herbage mass in both pasture treatments decreased with increasing stocking rate, but at 12.5 wethers/ha, lucerne herbage mass was significantly (P<0.001) greater than annual pasture herbage mass. Sheep liveweight showed similar trends. On annual pastures, wool production per sheep decreased with increasing stocking rate, whereas on lucerne, it was maintained as stocking rate increased from 8.75 to 12.5 wethers/ha. Mean wool production per ha on lucerne pasture was 14.5, 23.5, and 32.1 kg for 5.0, 8.75, and 12.5 wethers/ha, respectively, and on annual pasture it was 13.8, 21.7, and 24.8 kg. Supplementary feeding was needed on annual pastures every year at the high stocking rate. On lucerne pastures, it was unnecessary except for 3 weeks in 1991. Soil moisture under lucerne was less than under annual pasture, indicating that lucerne used more water than the annual pasture and created a larger soil water deficit, thus leading to potentially less groundwater recharge. In this environment, lucerne could be productively stocked at 12.5 wethers/ha, whereas annual pastures were less productive and could only be stocked at 8.75 wethers/ha. Furthermore, lucerne was more effective at using soil water and reducing the potential for groundwater recharge.

Supplementary feeding pattern and rate of liveweight gain in winter-spring affect wool production of young Merino sheep on the south coast of Western Australia

1995 ◽  
Vol 35 (8) ◽  
pp. 1093 ◽  
Author(s):  
PT Doyle ◽  
TW Plaisted ◽  
RA Love
Keyword(s):  
Growth Rates ◽  
Management Strategies ◽  
Fibre Diameter ◽  
Supplementary Feeding ◽  
Stocking Rate ◽  
Merino Sheep ◽  
Wool Production ◽  
Wool Growth ◽  
Staple Strength ◽  
Stocking Rates

The effects of different supplementary feeding practices in summer-autumn and management strategies on green pasture on liveweight change, wool growth rate, annual wool production and wool characteristics of young Merino wethers were examined at 2 farms. The grain feeding treatments were lupins (L) or lupins and oats (LO) fed in amounts that were adjusted to try and maintain liveweight, or lupins and oats (LOG) fed at a higher rate. The objectives of liveweight maintenance or gain were not always achieved, but liveweight patterns differed between LOG compared with L or LO during summer-autumn. The sheep used at farm 1 were aged 4.5 months and liveweight 32 kg at the start of the experiment, while those at farm 2 were 6.5 months and liveweight 39 kg. The stocking rate in summer-autumn was 8 wethers/ha at both farms. During supplementation, sheep on LOG had a higher (P<0.05) liveweight change compared with those on L or LO (farm 1, 15 v. -8 g/sheep. day; farm 2, -35 v. -51 g/sheep. day) and clean wool growth rates (farm 1, 7.1 v. 6.4 g/sheep. day; farm 2, 5.1 v. 4.8 g/sheep.day). The sheep on LOG grew broader (P<0.05) wool than those on L or LO (farm 1, 19.0 v. 18.5 �m; farm 2, 21.7 v. 20.8 �m), and at farm 1 length was also greater (P<0.05) (114 v. 111 mm), while at farm 2 staple strength was greater (P<0.01) (22.9 v. 16.4 N/ktex). There were no significant differences in annual clean wool production. There were positive (P<0.01) relationships between staple strength and liveweight change to the time of minimum liveweight in summer-autumn. After green pasture on offer reached 500 kg DM/ha in autumn, different liveweight change patterns were achieved in 2 groups (LS, lower stocking rates; HS, higher stocking rates) of sheep at each farm by adjusting stocking rates. Within a farm, the LS and HS groups were comprised of equal numbers of sheep from each replicate of the supplementary feeding treatments. There were differences (P<0.05 to 0.01) in liveweight change between LS and HS (farm 1, 93 v. 72 g/day; farm 2, 127 v. 60 g/day), the differences being more pronounced at farm 2. The differential stocking rates at farm 2 resulted in differences in clean wool growth rates (P<0.01), in clean wool production (4.22 v. 4.53 kg, P<0.05), and fibre diameter (20.8 v. 21.4 �m, P<0.01), but there were no significant effects on staple length or strength. There were no significant effects of the supplementary feeding treatments imposed in summer-autumn on the responses to the stocking rate treatments on green pasture.

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.

Subclinical selenium insufficiency. 5. Selenium status and the growth and wool production of sheep supplemented with thyroid hormones

1994 ◽  
Vol 34 (1) ◽  
pp. 13 ◽  
Author(s):  
GE Donald ◽  
JP Langlands ◽  
JE Bowles ◽  
AJ Smith
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Subcutaneous Injection ◽  
Significant Interaction ◽  
Fibre Diameter ◽  
Selenium Status ◽  
Merino Sheep ◽  
Wool Production ◽  
Grazed Pastures ◽  
Fleece Weight

Fine wool Merino sheep grazed pastures low in selenium (Se) in 2 experiments, and were supplemented with Se and thyroxine (T4) in experiment 1, and with Se, T4, and tri-iodothyronine (T3) in experiment 2. Both experiments ran for 6 months. In experiment 1, 72 sheep with a mean liveweight of 37 kg were given Se by intraruminal pellet and 6 levels of T4 ranging from 0 to 10 mg sodium L-thyroxine as a subcutaneous injection at 14-day intervals. In experiment 2, 36 sheep with a mean liveweight of 24 kg were given Se by intraruminal pellet, and 3 levels of T4 ranging from 0 to 0.4 mg and 3 levels of T3 ranging from 0 to 0.1 mg by subcutaneous injection at weekly intervals. In both experiments wool production and mean fibre diameter were significantly increased by Se supplementation; the increase in clean fleece production was 7 and 32% in experiments 1 and 2, respectively. In experiment 1, T4 increased greasy fleece weight by up to 8% and reduced yield, mean fibre diameter, and liveweight. In experiment 2, T4 reduced fibre diameter. T3 did not significantly affect wool production, wool characteristics, or liveweight. There was no significant interaction between Se and thyroid hormone supplementation in either experiment. Thyroid hormones were used as effectively for wool production by both Se-deficient and Se-sufficient sheep.

scholarly journals ENVIRONMENTAL AND GENETIC EFFECTS ON PRODUCTION TRAITS OF EWES ORIGINALLY FROM DISTINCT ENVIRONMENTS

1993 ◽  
Vol 23 (3) ◽  
pp. 347-350
Author(s):  
Nelson Manzoni de Oliveira ◽  
José Carlos Ferrugem Moraes
Keyword(s):  
Reproductive Performance ◽  
Selection Criteria ◽  
Farm Management ◽  
Production Traits ◽  
Stocking Rate ◽  
Wool Production ◽  
Management Procedures ◽  
Potential Factor ◽  
Production Areas ◽  
Improved Pasture

Wool production and reproductive performance components of similar genotypes, brought from distinct production areas, were evaluated during five years trial at similar environments, such as, joining season and stocking rate on winter improved pasture. The least squares means revealed that the origin (breed) effect concentrated upon the Corriedale ewes wool production, whereas in Romney females it affected the reproductive performance. In the abscence of interaction between origin (breed) and year for most variables, it was assumed that the farm management procedures and/or selection criteria applied on hoggets were determinant of the subsequent lifetime production within each genotype examined. Expecting a better reproductive performance in Romneys, mainly rate of lambs born, weaned and lambs weaning weight, comments were made on the selection criteria employed on this breed over many years. The work has demonstrated that "property of origin (breed)" of sheep composing any experiment aiming at breed comparisons, should be considered as a potential factor capable of biasing information on productive aspects.

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