Effects of experimentally produced local subdermal temperature changes on skin temperature and wool growth in the sheep

1970 ◽  
Vol 74 (1) ◽  
pp. 83-90 ◽  
Author(s):  
A. G. Lyne ◽  
M. Jolly ◽  
D. E. Hollis
Keyword(s):  
Growth Rate ◽  
Fibre Diameter ◽  
Slight Reduction ◽  
Environmental Disturbances ◽  
Temperature Changes ◽  
Merino Sheep ◽  
Cooling Period ◽  
Length Growth ◽  
Wool Growth ◽  
Change In Mean

SUMMARYA heat-exchange chamber made of perspex was inserted beneath the skin of a Merino sheep. By passing water at predetermined temperatures through the chamber, the normal subdermal temperature of 37°C was raised approximately 4°C for 4 days, then lowered approximately 5°C for 4 days.In response to heating, the animal's temperature regulating mechanism was able to maintain a fairly constant subdermal temperature. However, it was unable to maintain as constant a subdermal temperature in response to cooling. There was, during the cooling period, an obvious nervous response to environmental disturbances manifested by sudden transient decreases in subdermal temperature over the chamber.During the cooling period there was a decrease of 12% in mean length growth rate of wool over the chamber but mean fibre diameter was unchanged. Heating produced a small decrease in mean fibre diameter, but no change in mean length growth rate. Heating appeared to produce a slight reduction in pigmentation of some fibres but neither heating nor cooling produced demonstrable changes in crimping.

The response of skin and wool growth to local subdermal temperature changes in a sheep

1970 ◽  
Vol 75 (3) ◽  
pp. 501-515 ◽  
Author(s):  
M. Jolly ◽  
A. G. Lyne
Keyword(s):  
Growth Rate ◽  
Marked Reduction ◽  
Fibre Diameter ◽  
Progressive Decrease ◽  
Epidermal Thickness ◽  
Sebaceous Glands ◽  
Temperature Changes ◽  
Length Growth ◽  
Heating And Cooling ◽  
Wool Growth

SUMMARYHeat-exchange chambers, one for heating and one for cooling, were surgically embedded beneath the skin of a sheep. The intensity of heating and cooling was progressively increased, producing average subdermal temperatures up to 50·3 °C over one chamber and down to 21·0 °C over the other. The normal subdermal temperature was 37·7 °C.Moderate heating produced a small increase in the length growth rate of wool over the hot chamber. Higher temperatures caused a marked reduction and with still further heating there was almost complete cessation of wool growth.In contrast to heating, cooling always caused a suppression of wool growth which became more pronounced as the degree of cooling was intensified. The length growth rate decreased to half of normal at one stage but it never ceased.There was evidence of a slight but progressive decrease in fibre diameter with increasing subdermal temperatures up to 45 °C but at a temperature of 48 °C many of the fibres exhibited a marked thickening. Cooling the skin had little effect on fibre diameter. Pigmentation of the fibres was unchanged throughout the whole range of temperatures used and there was no evidence of change in crimping of the fibres.Heating in the range 45–50 °C produced an increase in epidermal thickness. Sweat and sebaceous glands, and erector muscles appeared unchanged after heating or cooling but innervation of the skin appeared to be reduced by extreme heating.The skin and wool growth over a dummy chamber were normal and similar in all respects to that in other control areas.

The influence of abomasal supplements of methionine on wool growth of wheat-fed sheep

1974 ◽  
Vol 25 (6) ◽  
pp. 919 ◽  
Author(s):  
PJ Reis ◽  
DA Tunks
Keyword(s):  
Amino Acids ◽  
Growth Rate ◽  
Blood Plasma ◽  
Fibre Diameter ◽  
Length Growth ◽  
Wool Growth ◽  
Abomasal Infusion ◽  
Mineral Mixture ◽  
In Blood Plasma

Sheep receiving a diet consisting solely of wheat (500 g/day), supplemented with a mineral mixture, were given abomasal infusions of varying amounts of DL-methionine (1.5–6.0 g/day) or of L-cystine (5 g/day). Other sheep received DL-methionine as a supplement to a roughage diet. All levels of methionine infused caused a decrease in the mass of wool grown by sheep consuming the wheat diet. This effect was greatest with 6 g methionine and was due mainly to a considerable depression of fibre diameter. Smaller amounts of methionine decreased fibre diameter and increased length growth rate. The infusion of methionine caused a considerable weakening of the wool grown by most of the sheep, with the result that a 'break' was observed in the fleece after about 1 week of methionine administration. This effect occurred with all levels of methionine but was more pronounced with 6 g/day. The abomasal infusion of cystine (5 g/day) caused little change in the mass of wool grown, but fibre diameter was decreased slightly. There were no appreciable effects on the strength of wool fibres and no wool was shed. Supplementation of the roughage diet (400 g/day) with methionine at 2 g/day stimulated wool growth, whereas with 6 or 10 g/day the mass of wool grown was unchanged but fibre diameter was markedly reduced. The strength of wool fibres was not markedly influenced by methionine infusions on this diet. The levels of amino acids in blood plasma and in abomasal digesta indicated that the mixture of amino acids absorbed was similar with both the roughage and the wheat diets.

Effects of shearing time and time of lambing on wool growth and processing characteristics

1984 ◽  
Vol 24 (126) ◽  
pp. 337 ◽  
Author(s):  
GW Arnold ◽  
AJ Charlick ◽  
JR Eley
Keyword(s):  
Growth Rate ◽  
Seasonal Pattern ◽  
Fibre Diameter ◽  
Fibre Length ◽  
Lower Percentage ◽  
Dominant Factor ◽  
Lower Yield ◽  
Merino Sheep ◽  
Wool Growth ◽  
Fleece Weight

Wool growth rate, seasonal pattern of fibre diameter, clean fleece weight, quality and the processing characteristics of wool were measured on medium-wool Merino sheep shorn in March (autumn) or October (spring) coupled with March or June lambing. These four management systems were compared under two nutritional regimes in the medium rainfall area of Western Australia. The sheep grazed annual pastures only, or had lupin grain and stubble during summer in addition to the pasture. The study ran for two shearing periods. Time of shearing was the dominant factor. Sheep shorn in March produced 14% more clean wool and fewer tender fleeces than sheep shorn in October. The autumn wool had a lower yield, higher fibre diameter and when processed had a higher card loss, lower percentage noil and lower top and noil yield. However, mean fibre length in the top was substantially higher and the variation in fibre length lower. Vegetable matter was higher in autumn shorn wools. There were some interacting effects of lambing time and type of feed regime. Sheep fed lupins had lower yielding wool but this effect was more pronounced in June lambings and was reflected in differences in top and noil yield. From measurements of wool growth rate, it was found that the extra wool was produced in autumn after shearing, due possibly to stimulated appetite that cannot occur after spring shearing because the sheep are too fat.

Intake and long-term cysteine supplementation change wool characteristics of Romney sheep

2001 ◽  
Vol 52 (1) ◽  
pp. 29 ◽  
Author(s):  
R. G. Sherlock ◽  
P. M. Harris ◽  
J. Lee ◽  
G. A. Wickham ◽  
J. L. Woods ◽  
...  
Keyword(s):  
Growth Rate ◽  
Treatment Period ◽  
Fibre Diameter ◽  
Wool Fibre ◽  
Amino Acid Supplementation ◽  
Sulfur Concentration ◽  
Treatment Groups ◽  
Length Growth ◽  
Wool Growth ◽  
Pre Treatment

Sulfur amino acid supplementation increases wool production in sheep at low planes of nutrition but it is unclear whether there is any benefit of supplementation at planes of nutrition above maintenance and what implications this might have for wool quality characteristics. This experiment directly investigated the interaction between sulfur supplementation and plane of nutrition in terms of wool growth and fibre characteristics. Twenty-four Romney ewes, acclimatised in individual metabolism units over a 7-week pre-treatment period, were allocated to 1 of 4 treatment groups based on a 22 factorial arrangement. Groups were low (L) or high (H) intake (0.8 or 1.3 maintenance, respectively) with continuous intravenous infusion of either saline (–Cys) or cysteine (+Cys, 2 g/day). During the 3-month treatment period, measurements were obtained for liveweight, plasma cysteine concentration, wool sulfur concentration and output, clean wool growth, mean fibre diameter (MFD), length growth rate (LGR), colour, loose wool bulk, handle, and crimp frequency and character. Clean wool growth response (P < 0.05) to cysteine supplementation was greater for the L sheep (6.06 v. 4.31 g/100 cm2) than the H sheep (7.20 v. 6.13 g/100 cm2). The response to supplementation in LGR (P < 0.01) was similar in both H (14%) and L (20%) sheep. There was no response in MFD due to sulfur supplementation, although fibre diameter measurements made along the fibres suggest that there was a response in L but not H sheep (P < 0.1). Wool sulfur concentration and output increased as a result of cysteine supplementation but concentration increased more in L (30.6 v. 24.5 mg S/g; P < 0.01) than in H sheep (28.4 v. 26.2 mg S/g). Qualitative electrophoresis analyses suggested that the increase in wool sulfur was achieved primarily by an increase in ultra-high-sulfur proteins. Crimp frequency and character were both significantly (P < 0.01) enhanced by cysteine supplementation. It is concluded that cysteine supplementation, at feed intakes that commonly occur in the commercial situation, can produce a useful increase in wool growth. This growth increase is primarily accomplished by increasing length growth rate rather than fibre diameter, which should also improve the value of the wool fibre produced.

The influence of abomasal supplements of zein and some amino acids on wool growth rate and plasma amino acids

1976 ◽  
Vol 86 (3) ◽  
pp. 475-482 ◽  
Author(s):  
P. J. Reis ◽  
D. A. Tunks
Keyword(s):  
Amino Acids ◽  
Growth Rate ◽  
Volume Growth ◽  
Fibre Diameter ◽  
Essential Amino Acids ◽  
Fibre Volume ◽  
Plasma Amino Acids ◽  
Leucine Supplementation ◽  
Length Growth ◽  
Wool Growth

SummaryMerino sheep were given abomasal infusions of (i) zein (80 g/day), (ii) zein (80 g/day) supplemented with L-lysine (6 g/day), L-tryptophan (1 g/day) or lysine and tryptophan together, or (iii) L-leucine (20 g/day). Effects on wool growth (length growth rate, fibre diameter, fibre volume growth rate and mass of wool grown) and on plasma amino acids were measured.Zein increased length growth rate and decreased fibre diameter; on average the volume growth rate and mass of wool grown were not significantly altered. The addition of tryptophan to the infusion of zein did not significantly alter wool growth, whereas the addition of lysine significantly increased all aspects of wool growth. The responses to these treatments were rapid and were adequately assessed during 12-day infusion periods. The infusion of leucine did not cause any appreciable changes in wool growth.Leucine supplementation increased the concentration of leucine in blood plasma about six-fold. Zein decreased the concentration of lysine and ornithine in plasma and increased the concentration of several essential amino acids; leucine was increased about seven-fold. The addition of tryptophan to zein had no effects on plasma amino acids, whereas lysine decreased the concentration of several amino acids in plasma and markedly increased lysine.

Strip grazing to control wool growth rate of sheep grazing green annual pastures

1999 ◽  
Vol 39 (3) ◽  
pp. 247 ◽  
Author(s):  
J. Young ◽  
P. T. Doyle ◽  
P. Booth
Keyword(s):  
Growth Rate ◽  
Production Systems ◽  
Fibre Diameter ◽  
Matter Content ◽  
Stocking Rate ◽  
Merino Sheep ◽  
Wool Growth ◽  
Staple Strength ◽  
Sheep Production ◽  
Strip Grazing

We compared strip grazing (SG) as a means of controlling wool growth rate, reducing variation in fibre diameter along the staple, and of carrying more Merino sheep through winter on green annual pastures, with set stocking (SS) in 3 experiments. In experiments 1 and 2, SG involved grazing to a residual feed on offer (FOO) of 400 kg DM/ha with an estimated intake of about 0.8 kg DM/day for each sheep. Treatments commenced after pasture establishment in autumn–winter, with both treatments stocked at 20 wethers/ha until late spring. During spring, average liveweight changes were lower (P<0.01) under SG than SS (55 v. 153 g/day experiment 1; –16 v. 217 g/day experiment 2). Strip grazing, compared with SS, reduced (P<0.01) the variation in wool growth rate and fibre diameter along the staple leading to lower (P<0.01) clean wool weights (3.54 v. 3.94 and 2.97 v. 4.12 kg), but finer (P<0.01) (20.9 v. 22.0 and 19.5 v. 21.5 mm), stronger (P<0.01) (28.6 v. 25.3 and 39.9 v. 35.5 N/ktex) wool. However, there was also an increase in vegetable matter content of the wool. The effects on annual pastures were to increase grass (79 v. 48 and 59 v. 25%) and reduce legume (12 v. 36 and 22 v. 54%) content at the end of spring. In experiment 3, two strip grazing treatments were used: SGl with a residual FOO of about 400 kg DM/ha and a stocking rate of 28 wethers/ha; and SGh with a residual FOO of about 800 kg DM/ha and stocking rate of 14 wethers/ha. The stocking rate for SS was 12 wethers/ha. SGl, following an autumn deferment, enabled a stocking rate of 28 wethers/ha to be sustained through winter without supplementary feeding. This is substantially higher than the district average stocking rate of about 7 sheep/ha. Strip grazing reduced (P<0.01) liveweights at the completion of treatments (SGl 41.9 v. SGh 47.9 v. SS 60.3 kg), reduced (P<0.01) clean wool weights (3.40 v. 3.72 v. 4.54 kg) and mean fibre diameter (19.1 v. 19.0 v. 20.9 m), but increased staple strength (21.3 v. 19.0 v. 16.9 N/ktex). These results are discussed in relation to opportunities to utilise strip grazing in sheep production systems on annual pastures in south-western Australia.

Keratin gene expression in Merino sheep with divergent wool growth

2005 ◽  
Vol 56 (3) ◽  
pp. 203 ◽  
Author(s):  
M. Bray ◽  
D. K. Revell ◽  
C. S. Bawden ◽  
P. I. Hynd
Keyword(s):  
Gene Expression ◽  
Growth Rate ◽  
Fibre Diameter ◽  
Cortical Cells ◽  
Keratin Gene ◽  
Merino Sheep ◽  
S Gene ◽  
Wool Growth ◽  
Estimated Breeding Values ◽  
Wool Proteins

South Australian Merino sheep were selected on the basis of high or low estimated breeding values (EBV) for wool growth rate (W), but with similar bodyweight, follicle density, and mean fibre diameter. Differences in the level of expression of keratin genes were examined in the skin of these sheep to test the hypothesis that divergence in EBV for wool growth is related to the production of wool proteins differing in sulfur (S) content. Further, it was proposed that this differential gene expression would be most pronounced when the supply of S amino acids to the animal was increased. Sheep selected for high EBV (+W) produced more wool per day than low EBV sheep (–W) (on average 32.5 v. 17.7 g/day clean wool, respectively; P < 0.05) but the S content of the wool did not differ between selection groups (2.77% v. 2.87% S, respectively; P = 0.2). Expression of keratin genes including keratin-associated protein KAP 2 (a high S gene), KAP 4 (an ultra-high S gene), KAP 6 (a high glycine/tyrosine gene), and the intermediate filament gene K 2.10, did not differ significantly between +W and –W groups. KAP 2 and K 2.10 each accounted for approximately 5% of the variation in wool growth rate (WGR) but expression of none of the genes examined was significantly related to the S content of the fibre produced. This suggests that differential keratin gene expression was not the source of genetic divergence in WGR. Instead the latter likely reflects a combination of differential cellular rate and growth processes (e.g. rate of bulb cell production, hypertrophy of cortical cells), differences in the relative production of inner root sheath and fibre from the follicle bulb cell population, or differential nutrient uptake into the follicle.

Supplementation of young Merino sheep grazing annual pastures with lupin, barley grain, or silage

1993 ◽  
Vol 33 (4) ◽  
pp. 403 ◽  
Author(s):  
JJ Gardner ◽  
PT Doyle ◽  
JB Rowe ◽  
R Hetherington ◽  
P Spicer ◽  
...  
Keyword(s):  
Growth Rate ◽  
Energy Levels ◽  
Fibre Diameter ◽  
Barley Grain ◽  
Sheep Grazing ◽  
Merino Sheep ◽  
Wool Growth ◽  
Metabolisable Energy ◽  
Staple Strength ◽  
Fleece Weight

We examined the effects on liveweight change and wool production of supplements of lupin, barley grain, or silage given to Merino weaners (age 5-7 months; starting weight about 30 kg) grazing dry annual pastures. In experiment 1, each supplement was offered at 5 rates (g/sheep.day): lupin, air-dry, 75-450; barley, air-dry, 80-480; silage, fresh, 430-2580. Sheep on all treatments gained weight in the first 29 days of supplementary feeding, with no effect of rate of supplementation (lupin 97 g/day; barley 57 g/day; silage 74 g/day). Those receiving no supplement also gained weight (40 g/day). Different supplements were not compared because the energy levels of lupin and barley were not measured. Over the next 48 days, liveweight changes increased (P<0.001) linearly with rate of feeding of lupin (25 � 2.1 g/100 g) and barley (12 � 0.8 g/100 g). The trend with silage (11 � 5.0 g/kg) was not significant. Taken over the 77 days, liveweight changes increased (P<0.01) linearly with rate of feeding for lupin (20 �. 1.8 g/100 g), barley (8 �. 1.7 g/100 g), and silage (10 �. 2 g/kg). There were no significant (P>0.05) differences associated with the rate of supplementation for annual clean fleece weight (lupin 3.43 kg, barley 3.37 kg, silage 3.30 kg) or mean fibre diameter of the 12-month fleece (lupin 22.2 �m, barley 22.6 �m, silage 22.1 �m). In experiment 2, sheep were given no supplement, lupin, barley, or lupin and barley mixtures (metabolisable energy ratio, 1:3,1:1,3:1). All supplements increased liveweight change (P<0.01) and clean wool growth rates (P<0.05) compared with no supplement. There was also a trend towards an increase in total wool grown by supplemented sheep (3.8 - 4.00 v. 3.73 kg). Liveweight change during the first 71 days of feeding increased (P<0.01) as the proportion of lupin in the supplement increased, with no effects in the final 70 days of supplementation. During supplementation, clean wool growth rate increased (P<0.05) as the proportion of lupin in the mixture increased, but there was no significant effect on the total amount of wool grown over 12 months or on mean fibre diameter. Supplements resulted in increased (P<0.001) staple strength when compared with controls (21-25 v. 14 N/ktex).

Wool growth regulation by local skin cooling

1967 ◽  
Vol 9 (3) ◽  
pp. 393-397 ◽  
Author(s):  
J. M. Doney ◽  
J. G. Griffiths
Keyword(s):  
Heat Transfer ◽  
Growth Rate ◽  
Blood Flow ◽  
Growth Regulation ◽  
Fibre Diameter ◽  
Systemic Response ◽  
Local Cooling ◽  
Local Skin ◽  
Wool Growth ◽  
Skin Cooling

Local cooling of the skin, produced by exposure to wind was shown to depress the rate of length growth of wool. The depression was associated with reductions in skin temperature and blood flow and with increases in heat transfer in the exposed regions. Fibre diameter did not appear to be affected and there were no indications of a systemic response of wool growth rate to exposure.

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.

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