scholarly journals Effects of Intravenous Infusion of Mimosine on Wool Growth of Merino Sheep

1975 ◽  
Vol 28 (6) ◽  
pp. 483 ◽  
Author(s):  
PJ Reis
Keyword(s):  
Amino Acids ◽  
Intravenous Infusion ◽  
Merino Sheep ◽  
Wool Growth ◽  
Intravenous Infusions

Merino sheep were given continuous intravenous infusions of L-mimosine for periods of It, 2 or 21 days; efficacy as a defleecing procedure and effects on subsequent wool growth were measured. In addition, the amino acids tyrosine, phenylalanine and cystine were investigated as antagonists to the effects of mimosine.

scholarly journals Effects of Growth Hormone Administration on Wool Growth in Merino Sheep

1988 ◽  
Vol 41 (2) ◽  
pp. 177 ◽  
Author(s):  
PC Wynn ◽  
ALC Wallace ◽  
AC Kirby ◽  
EF Annison
Keyword(s):  
Amino Acids ◽  
Growth Hormone ◽  
Energy Intake ◽  
Nitrogen Balance ◽  
Daily Administration ◽  
Maintenance Energy ◽  
Merino Sheep ◽  
Growth Hormone Administration ◽  
Hormone Administration ◽  
Wool Growth

The effects of daily administration of 10 mg of highly purified ovine growth hormone (GH) for a period of 4 weeks on wool growth have been measured in 12 Merino ewes fed either a calculated maintenance energy intake or 1�6 times this amount (six on each ration). Concentrations of hormones, glucose, urea, a-amino N and amino acids in the blood were monitored and faeces and urine collected for measurement of nitrogen balance.

scholarly journals Effect of Intravenously Infused Dexamethasone on Collagen Metabolism in Skin of Merino Sheep

1979 ◽  
Vol 32 (6) ◽  
pp. 561
Author(s):  
Z Leish ◽  
BA Panaretto
Keyword(s):  
Body Weight ◽  
Intravenous Infusion ◽  
Collagen Metabolism ◽  
Merino Sheep ◽  
Wool Growth

The effects of an 8-day intravenous infusion of dexamethasone (7�6 mg kg-o.75 body weight) on collagen biosynthes's and wool growth in skin were examined in four Merino wethers.

scholarly journals Metabolism of Cystine by Merino Sheep Genetically Different in Wool Production III. the Incorporation of Radioactivity Into Wool Fibres During and After Intravenous Infusions of l-[35S]Cystine and its Relationship to Wool Growth and Efficiency of Conversi

1973 ◽  
Vol 26 (2) ◽  
pp. 465 ◽  
Author(s):  
AJ Williams
Keyword(s):  
Merino Sheep ◽  
Wool Production ◽  
Wool Growth ◽  
Intravenous Infusions ◽  
Fleece Weight ◽  
Dietary Treatments

Twelve mature ewes from a flock selected for high clean fleece weight (Fleece Plus) and twelve from a flock selected for low clean fleece weight (Fleece Minus) were randomly divided between two dietary treatments: 500 or 1100 g per day of chaffed lucerne hay.

Effects of the infusion of amino acids into the abomasum of sheep, with emphasis on the relative value of methionine, cysteine and homocysteine for wool growth

1990 ◽  
Vol 114 (1) ◽  
pp. 59-68 ◽  
Author(s):  
P. J. Reis ◽  
D. A. Tunks ◽  
S. G. Munro
Keyword(s):  
Amino Acids ◽  
Folic Acid ◽  
Adverse Effects ◽  
Essential Amino Acids ◽  
Vitamin B ◽  
Merino Sheep ◽  
Wool Growth ◽  
Relative Value ◽  
Nonessential Amino Acids ◽  
Maintenance Ration

SUMMARYMerino sheep were given abomasal infusions of various amino acids or mixtures of amino acids. Effects on wool growth were measured using autoradiography or a clipping procedure and changes in the concentration of amino acids in plasma were measured in some experiments.Mixtures of five (28 g/day) or ten (45 g/day) essential amino acids (both mixtures containing 3 g methionine) stimulated wool growth of sheep receiving a maintenance ration; on average, the volume of wool grown increased 48% and 86%, respectively. When cysteine completely replaced methionine in these mixtures, wool growth was markedly reduced, but two-thirds of the methionine could be replaced by cysteine without affecting wool growth. Homocysteine was partially effective in replacing methionine and, when supplemented with betaine, folic acid and vitamin B12, the mixture was still significantly inferior to that containing methionine. In contrast, abomasal supplements of methionine or homocysteine alone were equivalent as supplements for wool growth. The results indicated a specific role for methionine in the control of wool growth, other than the provision of cysteine. This role was postulated to be related to some function of S-adenosylmethionine.Infusion often essential amino acids caused appreciable increases in the concentrations of cystine, methionine, cystathionine and taurine in plasma; total essential amino acids increased threefold whereas nonessential amino acids decreased in concentration. The replacement of methionine in the infusion by cysteine or homocysteine significantly altered the concentration of cystine, methionine and cystathionine in plasma.Evidence was obtained that the adverse effects on wool growth of high abomasal doses of methionine (10g/day) could not be reduced or prevented by provision of additional glycine and were not related to the supposed toxic effects of 3-methylthiopropionic acid, a metabolite of the transamination pathway.

scholarly journals Variation in the Sulphur Content of Wool of Merino Sheep Associated with Genetic Differences in Wool-Producing Capacity

1966 ◽  
Vol 19 (6) ◽  
pp. 1179 ◽  
Author(s):  
LR Piper ◽  
CHS Dolling
Keyword(s):  
Amino Acids ◽  
Seasonal Variation ◽  
Nutritional Status ◽  
Inverse Relationship ◽  
Copper Deficiency ◽  
Sulphur Content ◽  
Merino Sheep ◽  
Wool Growth ◽  
Number Of Factors ◽  
The Relationship

The sulphur content of wool may be influenced by a number of factors. Copper deficiency has been shown to reduce sulphur content (Marston 1946), while the administration of sulphur-containing amino acids or casein directly into the abomasum has been shown to increase substantially both the sulphur content of wool and the rate of wool growth (Reis and Schinckel1961, 1963, 1964). Variation in the nutritional status of both pen-fed (Reis 1965) and grazing (Reis and Williams 1965) sheep, associated with variation in either the amount or the composition of the diet, has also been shown to influence sulphur content; wool growth and sulphur content have both increased as nutrition has been improved, and vice versa. Variation in the sulphur content of wool from grazing sheep has also been reported by Ross (1961, 1964) who suggested that there was an inverse relationship between rate of wool growth and its sulphur content. The sheep observed by Ross were Romney ewes and Reis and Williams (1965) have cast some doubt on the relationship suggested by Ross on the grounds that the seasonal variation in wool growth may have been affected by factors other than nutrition.

Effects of abomasal protein and energy supply on wool growth in Merino sheep

1992 ◽  
Vol 43 (6) ◽  
pp. 1353 ◽  
Author(s):  
PJ Reis ◽  
DA Tunks ◽  
SG Munro
Keyword(s):  
Amino Acids ◽  
Energy Supply ◽  
Essential Amino Acids ◽  
Merino Sheep ◽  
Lattice Design ◽  
Wool Growth ◽  
Extra Energy ◽  
Whole Milk ◽  
Wool Proteins ◽  
Protein Supply

The relative importance for wool growth of energy-yielding nutrients compared with amino acids required for incorporation into wool proteins was assessed in an experiment in which most nutrients were supplied via the abomasum. Nine nutritional treatments, providing three levels of protein (53, 99 and 145 g/day) to the intestines at three levels of energy (5.2, 7.5 and 9.7 MJ/day), were given to 12 Merino sheep during three consecutive periods of 3 weeks in a balanced lattice design. Abomasal nutrients consisted of varying proportions of casein, whole milk, glucose and glycerol. There was a large effect of protein supply on all components of wool growth, but there was no significant effect of energy. There was a significant interaction between the effects of protein and energy supply on diameter, length growth rate and volume of wool, but it was small relative to the main effect of protein. Extra energy appeared to enhance wool growth at the highest level of protein but reduce it at the lowest level of protein. The concentration of urea, cystine, methionine and other essential amino acids in plasma increased with protein level. Increasing energy supply reduced the concentration of urea and essential amino acids in plasma but not that of cystine or methionine. The experiment confirmed the major role of amino acid supply in controlling wool growth but indicated that there may be a small interaction with energy supply.

scholarly journals The Influence of Abomasal and Intravenous Supplements of Sulphur-Containing Amino Acids on Wool Growth Rate

1973 ◽  
Vol 26 (1) ◽  
pp. 249 ◽  
Author(s):  
PJ Reis ◽  
DA Tunks ◽  
AM Downes
Keyword(s):  
Amino Acids ◽  
Growth Rate ◽  
Wool Growth ◽  
Intravenous Infusions

Various amounts (0�6-10�0 g/day) of L-cystine, L-cysteine, and L- and DL-methionine were given as abomasal or intravenous infusions to 10 sheep, in three experiments.

scholarly journals Effects of Mimosine, a Potential Chemical Defleecing Agent, on Wool Growth and the Skin of Sheep

1975 ◽  
Vol 28 (1) ◽  
pp. 69 ◽  
Author(s):  
PJ Reis ◽  
DA Tunks ◽  
RE Chapman
Keyword(s):  
Intravenous Infusion ◽  
Intraperitoneal Injection ◽  
Continuous Intravenous Infusion ◽  
Merino Sheep ◽  
Wool Growth

Twenty-two Merino sheep were dosed with various amounts of L-mimosine, given either as an intravenous or an intraperitoneal injection, or as a continuous intravenous infusion for periods of 1-4 days.

The influence of nutrition on the effectiveness of mimosine for defleecing sheep

1978 ◽  
Vol 29 (5) ◽  
pp. 1057 ◽  
Author(s):  
PJ Reis ◽  
DA Tunks
Keyword(s):  
Amino Acids ◽  
Growth Rate ◽  
Intravenous Infusion ◽  
Continuous Intravenous Infusion ◽  
High Intake ◽  
Wool Growth ◽  
Abomasal Infusion ◽  
High Feed ◽  
Standard Rate ◽  
Small Intestines

The effectiveness of mimosine as a chemical defleecing agent was assessed in adult sheep that were subjected to a variety of nutritional treatments prior to administration of mimosine, and in lambs receiving relatively high feed intakes. Mimosine was given as a continuous intravenous infusion over a period of 2 days. Sheep receiving 600 g of a roughage-based diet per day were consistently defleeced following an infusion of mimosine at the rate of 80 mg/kg/day (designated the standard infusion). The prior feeding of a reduced intake of this diet (300 g/day) did not alter the amount of mimosine required to defleece sheep. Likewise, the prior abomasal infusion of an imbalanced mixture of amino acids, which depressed the wool growth rate, did not allow defleecing with a reduced amount of mimosine. A 4-day fast, commenced 3 days before the start of mimosine infusion, approximately halved the amount of mimosine required to defleece sheep. The provision of a high intake of energy, together with large amounts of amino acids available for absorption from the small intestines (supplied by casein), for at least 1 week prior to mimosine infusion, completely prevented defleecing with the standard infusion of mimosine. The effects of these nutritional treatments could be obviated by a 4-day fast as described above. Also, increasing the rate of infusion of mimosine to 120 mg/kg/day largely overcame the effects of previous high nutrition. Relatively greater amounts of mimosine were required to defleece lambs than adults. The concentration of mimosine in plasma was related to the rate of infusion of mimosine. However, fasting and a low dietary intake tended to enhance the concentration of mimosine in plasma for a given rate of infusion. Infusion of mimosine at the standard rate resulted in plasma mimosine concentrations of the order of 100 µmoles/l, but this concentration did not ensure that defleecing would be possible.

Efficiency of wool production of grazing sheep. 3. The use of sulphur-containing amino acids to stimulate wool growth

1970 ◽  
Vol 10 (47) ◽  
pp. 665 ◽  
Author(s):  
JP Langlands
Keyword(s):  
Amino Acids ◽  
Peritoneal Cavity ◽  
Sheep Grazing ◽  
Merino Sheep ◽  
Wool Production ◽  
Wool Growth ◽  
Grazing Sheep ◽  
Native Pastures

Merino sheep grazing native and improved pastures were given up to 2.2 g DL-methionine each day through an abomasal cannula. Wool growth of sheep grazing improved and native pastures was increased significantly by up to 30 and 41 per cent respectively. Nine sheep with abomasal camulae were maintained in pens, and were infused into the abomasum with 7 g DL-methionine per week given on either one, two, or seven days each week. Wool growth was significantly increased by daily infusions of DL-methionine but the response was less when the methionine was given on only one or two days each week. Dorset Horn wethers were given single injections of up to 50 g DL-methionine or L-cystine subcutaneously or into the peritoneal cavity. The rate of excretion of urinary sulphur was recorded following the injection. DL-methionine was rapidly excreted but L-cystine was excreted more slowly. In a series of trials quantities of DL-methionine, methionine hydroxy analogue (MHA) or L-cystine were injected subcutaneously or intra-peritoneally into grazing Merino sheep. DL-methionine did not increase wool growth and MHA was toxic. Twenty-eight g L-cystine given as two compressed pellets each month into the peritoneal cavity increased wool growth by approximately 22 per cent over the 8-week experim6ntal period.

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