Effect of glucose or amino acid infusion during pregnancy in ewes with different wool growth responsiveness to nutrition

2004 ◽  
Vol 55 (1) ◽  
pp. 47 ◽  
Author(s):  
M. J. Thompson ◽  
J. R. Briegel ◽  
N. R. Adams
Keyword(s):  
Amino Acids ◽  
Plasma Concentrations ◽  
Amino Nitrogen ◽  
Insulin Response ◽  
Late Pregnancy ◽  
Glucose Infusion ◽  
Control Line ◽  
Amino Acid Infusion ◽  
Wool Growth ◽  
Staple Strength

The reason why wool growth is suppressed in pregnancy is unclear. The present study examined the response to the nutrient drains imposed by pregnancy in 3 genotypes that had been selected for low (SS–) or high (SS+) staple strength, and a random control line. These flocks differ in the responsiveness of their protein metabolism to nutrient supply. Three groups of 20 pregnant ewes were fed to maintain conceptus-free liveweight, and were challenged with an infusion of glucose or amino acids in mid (Day 104) or late (Day 138) pregnancy. Infusion of glucose in late pregnancy caused a lower increment in plasma glucose concentration (P < 0.001) compared with mid-pregnancy, whereas plasma insulin responses to glucose infusion were not significantly different across time. In contrast, infusion of amino acids caused a greater increase in plasma concentrations of α-amino nitrogen in all genotypes in late pregnancy (P < 0.01), whereas the insulin response to amino acids was reduced (P < 0.001). Despite slower clearance of amino acids and decreased wool protein synthesis, the concentrations of blood urea nitrogen (BUN) were elevated in late pregnancy. The genotypes did not differ in their response to infusion with amino acids, but the SS– genotype had higher basal glucose and insulin concentrations. We conclude that the suppression in wool growth as pregnancy progresses was accompanied by greater oxidation but slower clearance of amino acids from plasma, associated with a lower insulin response. This defect in insulin response was selective for amino acids, because it was not observed in response to glucose infusion.

Plasma insulin concentrations and amino acid turnover in Merino sheep with high or low fleece weight

2004 ◽  
Vol 55 (8) ◽  
pp. 833 ◽  
Author(s):  
N. R. Adams ◽  
S. M. Liu ◽  
J. R. Briegel ◽  
M. J. Thompson
Keyword(s):  
Amino Acids ◽  
Plasma Insulin ◽  
Plasma Concentrations ◽  
Amino Nitrogen ◽  
Whole Body ◽  
Metabolic Demand ◽  
Body Protein ◽  
Wool Growth ◽  
Staple Strength ◽  
Fleece Weight

Although sheep with a relatively high fleece weight have reduced fat deposition and a lower reproductive rate, research has failed to identify any specific metabolic demand that growing a fleece places on the physiology of the sheep. This paper reports two experiments in which the effect of fleece weight was examined in ewes infused intravenously with amino acids. The first experiment was carried out when the ewes were 107 days pregnant, and the second 2 years later in non-pregnant ewes from the same flock. The ewes were derived initially from groups that differed in staple strength, but there was no effect of staple strength group on the characteristics measured in either experiment. In Expt 2, ewes were also infused with a bolus of l-[ring-d5] phenylalanine, and the enrichment in plasma determined by GC/mass spectrometry over the next 24 h. In both experiments, fasting plasma insulin concentrations were lower (P < 0.05) in ewes with a high fleece weight, and this difference continued during infusion in Expt 2 (P < 0.05). In Expt 1, infusion of ewes with amino acids resulted in higher (P < 0.05) plasma concentrations of α-amino nitrogen (indicating amino acids) in the ewes with a higher fleece weight, and in Expt 2, ewes with a high fleece weight had a 19% higher rate of appearance of endogenous phenylalanine (P < 0.05). We conclude that sheep with high wool growth rates have higher whole-body protein turnover rate, which may be achieved in part by lower insulin concentrations. Lower insulin in turn provides a mechanism through which wool growth rate may influence energy availability to other tissues.

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.

Responses in wool and live weight when different sources of dietary protein are given to pregnant and lactating ewes

1996 ◽  
Vol 62 (3) ◽  
pp. 497-506 ◽  
Author(s):  
D. G. Masters ◽  
C. A. Stewart ◽  
G. Mata ◽  
N. R. Adams
Keyword(s):  
Amino Acids ◽  
Birth Weight ◽  
Live Weight ◽  
Late Pregnancy ◽  
Early Lactation ◽  
Foetal Growth ◽  
Wool Growth ◽  
Pregnancy And Lactation ◽  
Staple Strength ◽  
Different Sources

AbstractWool growth, staple strength and fibre diameter are reduced during pregnancy and lactation. This may be due to the increased requirement for protein for foetal growth, udder development and milk production causing a lack of amino acids for wool. Responses in wool production, ewe live weight, lamb birth weight and growth, plasma amino acids and levels of cortisol, insulin and growth hormone were measured when different sources of protein were offered. Either lupin seed (L), fish meal (F) or formaldehyde-treated egg white (E) were included in an oaten hay-based diet offered during the final 3 weeks of pregnancy and first 3 weeks of lactation. Provision of diets containing E or F resulted in significant (P < 0·001) increases in wool growth and trends towards increased staple strength (4 to 6 N/ktex) and clean fleece weights (0·17 to 0·38 kg) compared with the sheep given L. Feeding the E diet increased the concentration of cystine in plasma and sulphur in wool in late pregnancy. Feeding the F diet increased the concentrations of arginine, histidine, lysine and threonine in plasma in early lactation. Ewes given E had higher circulating insulin and increased insulin resistance, compared with sheep given L, on 2 of the 4 days of sampling during pregnancy and lactation during the treatment period. There were no treatment effects on lamb birth weight or growth but ewes given the E diet were significantly (P < 0·05, 3·3 kg) heavier than the ewes given L after 3 weeks of lactation. The results indicate that a lack of protein available for absorption in the small intestine causes reduced wool growth during late pregnancy and early lactation. Wool growth is more sensitive to a reduced protein supply than foetal growth, maternal weight or milk production.

Effects of truncated glucagon-like peptide-1 on the responses of starved sheep to glucose

1991 ◽  
Vol 129 (1) ◽  
pp. 55-58 ◽  
Author(s):  
A. Faulkner ◽  
H. T. Pollock
Keyword(s):  
Plasma Insulin ◽  
Plasma Concentrations ◽  
Amino Nitrogen ◽  
Insulin Response ◽  
Not Given ◽  
Glucose Load ◽  
Glucose Administration ◽  
Gut Hormone ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

ABSTRACT The effects of i.v. glucagon-like peptide-1-(7–36)amide (GLP-1; 10 μg) on starved sheep given an i.v. glucose load (5 g) were studied. Plasma insulin concentrations rose significantly more after glucose administration in fed than in starved sheep. Giving GLP-1 to starved sheep increased the insulin response to the glucose load. The rise in plasma insulin concentrations in starved sheep given GLP-1 was similar to that observed in fed sheep. Plasma glucose concentrations returned to normal values more quickly in the starved sheep given GLP-1 than in starved sheep not given gut hormone. Plasma concentrations of free fatty acid, urea and α-amino nitrogen decreased more quickly following glucose administration in starved sheep given GLP-1 than in those not given GLP-1. The data suggest a role for GLP-1 in regulating plasma insulin concentrations and hence metabolism in ruminant animals. The possible role of gut hormones in ruminants is discussed. Journal of Endocrinology (1991) 129, 55–58

GLUCOSE TOLERANCE IN NEWBORN INFANTS OF HEALTHY MOTHERS: ITS RELATIONSHIP TO THE MOTHERS' INSULIN RESPONSE TO GLUCOSE INFUSION

1975 ◽  
Vol 78 (1) ◽  
pp. 44-53 ◽  
Author(s):  
Karin Edström ◽  
Erol Cerasi ◽  
Rolf Luft ◽  
Bengt Persson ◽  
Berlil Thalme
Keyword(s):  
Glucose Tolerance ◽  
Newborn Infants ◽  
Insulin Response ◽  
Late Pregnancy ◽  
Mean Difference ◽  
Glucose Infusion ◽  
K Value ◽  
High Insulin ◽  
The Mean ◽  
Low Insulin Response

ABSTRACT It has earlier been postulated that a low insulin response to a glucose infusion is characteristic for the prediabetic individual (Cerasi & Luft 1967c). There is also evidence that some infants of individuals with low insulin response might have a carbohydrate metabolism that is in some respects similar to that of newborn infants to diabetic mothers (Edström et al. 1974). In the present study 15 infants to low insulin responders (ILR) and 22 infants to high insulin responders (IHR) were subjected to an intravenous glucose load (IVGTT) at 2–24 h age. A significant difference in glucose tolerance was found between the groups, the mean k-value for the ILR being 1.39 ± 0.41 and that for the IHR 1.05 ± 0.09 (P < 0.05). No mothers were found to have a gestational diabetes (with the possible exception of one low insulin responders) but during late pregnancy the mean k-value at IVGTT in the low responders decreased from nonpregnant values (the mean difference being 0.41 ± 0.20, P < 0.025) while the high responders did not show a corresponding decrease (mean difference 0.12 ± 0.25, P > 0.05). No other differences between the groups of infants that could influence the k-value could be found apart from the mothers being low or high insulin responders. Our findings show that a low insulin response in the mothers might affect the glucose tolerance of the foetus even in the absence of continuous maternal hyperglycaemia in late pregnancy.

Effect of selection for wool growth on seasonal patterns of yield, fibre diameter, and colour in Romney lines

1995 ◽  
Vol 35 (1) ◽  
pp. 27 ◽  
Author(s):  
T Wuliji ◽  
IL Weatherall ◽  
RN Andrews ◽  
KG Dodds ◽  
PR Turner ◽  
...  
Keyword(s):  
Growth Rate ◽  
Fibre Diameter ◽  
Seasonal Patterns ◽  
Control Line ◽  
Wool Growth ◽  
Growth Decline ◽  
Selection For ◽  
Staple Strength ◽  
Fleece Weight

Seasonal wool growth and associated wool characteristics were measured in a Romney line selected for high fleece weight and an unselected control line in 1990 and 1991. Both had a significant (P<0.01) decline in wool growth rate in winter compared with summer. The wool growth rate advantage (P<0.001) of the selected line over the control averaged 19 and 33% for ewes, and 24 and 36% for hoggets, in summer and winter, respectively. Staple strength, yield, and fibre diameter differences were closely associated with wool growth. Colour analysis showed no difference between lines in either brightness (Y) or yellowness (Y - Z). However, both the Y and Z values were lower in spring and summer, while Y - Z was highest in summer. The results suggest that selection for high fleece weight also improves major wool characteristics and reduces the relative winter wool growth decline in Romneys.

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.

Changes in plasma amino acid patterns and wool growth in response to abomasal injections of amino acids during late pregnancy and early lactation

1993 ◽  
Vol 44 (5) ◽  
pp. 959 ◽  
Author(s):  
CA Stewart ◽  
DG Masters ◽  
IH Williams ◽  
PJ Connell
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Late Pregnancy ◽  
Early Lactation ◽  
Growth Responses ◽  
Specific Amino Acid ◽  
Protein Deposition ◽  
Wool Growth ◽  
Limiting Amino Acids ◽  
Sulfur Containing

Provision of sulfur-containing amino acids into the abomasum has increased wool production in non-reproducing sheep and, on the basis of such studies, they have generally been considered as the primary limiting nutrients for wool growth. The specific amino acid needs of reproducing ewes were investigated in the current study. Three groups of pregnant ewes were fitted with temporary abomasal fistulae. For the last 3-4 weeks of pregnancy and the first 3 weeks of lactation, solutions containing sodium hydroxide (as a carrier) or methionine or a mixture of valine, arginine, lysine and threonine (VALT) were injected into the abomasum twice per day. The injection of methionine did not increase protein deposition during pregnancy; this was indicated by the failure of the treatment to lower the concentration of other amino acids in plasma, or increase liveweight, lamb birth weight or wool growth. Responses in early lactation were different with the methionine injected sheep having a lower concentration of free lysine, valine, alanine and serine in plasma, indicating an increased rate of protein deposition, and a faster growth rate in the ewes. Injections of VALT caused a decrease in the concentration of cystine and methionine in plasma and depressed wool growth and tensile strength. Theresults indicate that a lack of methionine was not limiting protein deposition during late pregnancy, but may have been during early lactation. Valine, arginine, lysine and threonine were not the primary limiting amino acids in late pregnancy or early lactation.

scholarly journals The effect of glucose infusion on the plasma free amino acids in sheep

1975 ◽  
Vol 34 (3) ◽  
pp. 375-382 ◽  
Author(s):  
N. W. Offer ◽  
M. V. Tas ◽  
R. F. E. Axford ◽  
R. A. Evans
Keyword(s):  
Amino Acids ◽  
Free Amino Acids ◽  
Free Amino ◽  
Late Pregnancy ◽  
Essential Amino Acids ◽  
Glucose Infusion ◽  
Pregnant Sheep ◽  
Before And After ◽  
Effect Of Glucose ◽  
Plasma Free Amino Acids

1. Glucose in solution in saline, or saline alone, was administered to a group of twenty ewes during late pregnancy and again after lambing. Sequential blood samples were taken before and after the infusion and the concentration of plasma free amino acids was determined.2. The effect of glucose was to reduce the concentrations of all amino acids except alanine. The reduction was greatest for tryptophan in the pregnant sheep, but this amino acid showed no significant change in the lactating animals.3. An attempt to rank the amino acids on the basis of their response to glucose infusion indicated that, with the exception of tryptophan for the preparturient ewes, groups of essential amino acids could not be distinguished from each other. These groups were, for the preparturient sheep, valine, leucine, phenylalanine and isoleucine, and for the postparturient animals, isoleucine, lysine, methionine, valine and phenylalanine.

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