Release of Growth Hormone in Lactating and Non-Lactating Goats in Relation to Behaviour, Stages of Sleep, Electroencephalograms, Environmental Stimuli and Levels of Prolactin, Insulin, Glucose and Free Fatty Acids in the Circulation

Tindal, J. S.; Knaggs, G. S.; Hart, I. C.; Blake, L. A.

doi:10.1677/joe.0.0760333

Cited by 115 publications

(67 citation statements)

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“…Plasma insulin was assayed in duplicate in a single doubleantibody RIA (Tindal et al 1978) that had been validated for sheep plasma in our laboratory (Miller et al 1995). The limit of detection was 1.2 mU/ml.…”

Section: Blood Sampling Glucose and Hormone Assaysmentioning

confidence: 99%

Follicle development, endocrine profiles and ovulation rate in adult Merino ewes: effects of early nutrition (pre- and post-natal) and supplementation with lupin grain

et al. 2014

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In adult ewes, we tested whether ovarian function, including the response to short-term supplementation, was affected by the nutrition of their mothers during the pre-/post-natal period. A 2!2 factorial design was used with nutrition in early life (low or high) and a 6-day supplement (with or without) as factors. All ewes received three prostaglandin (PG) injections 7 days apart, and the supplement (lupin grain) was fed for 6 days from 2 days after the second until the third PG injection. We measured reproductive and metabolic hormones, studied follicle dynamics (ultrasonography), and evaluated granulosa cell numbers, aromatase activity and oestradiol (E 2 ) concentrations in follicular fluid in healthy follicles at days 3 and 7 of supplementation. Ovulation rate was increased by 25% by exposure to high pre-/post-natal nutrition (1.5 vs 1.2; P!0.05), in association with a small decrease in FSH concentrations (PZ0.06) and a small increase in insulin concentrations (PZ0.07). The number of healthy antral follicles was not affected. Acute supplementation increased the number of granulosa cells (3.7G0.2 vs 3.0G0.2 million; P!0.05) in the largest follicle, and the circulating concentrations of E 2 (4.6G0.3 vs 3.9G0.3 pmol/l; P!0.05) and glucose (3.4G0.03 vs 3.3G0.03 mmol/l; P!0.01). Both early life nutrition and acute supplementation appear to affect ovulation rate through changes in glucose-insulin homoeostasis that alter follicular responsiveness to FSH and therefore E 2 -FSH balance.

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Section: Blood Sampling Glucose and Hormone Assaysmentioning

confidence: 99%

Follicle development, endocrine profiles and ovulation rate in adult Merino ewes: effects of early nutrition (pre- and post-natal) and supplementation with lupin grain

et al. 2014

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“…The assay included six replicates of three control samples containing 0.43, 0.98 and 1.68 ng/ ml, which were used to estimate the intra-assay coefficients of variation of 6.1%, 6.0% and 6.5%, respectively. Plasma insulin was assayed in duplicate by a double-antibody radioimmunoassay (Tindal et al, 1978) that had been validated for sheep plasma (Miller et al, 1995). All samples were processed in a single assay and the limit of detection was 0.78 mU/ml.…”

Section: Experimental Designmentioning

confidence: 99%

Reproductive capacity of Merino ewes fed a high-salt diet

Digby

Masters

Blache

et al. 2008

Animal

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An option to increase the productivity of saline land is to graze sheep on salt-tolerant plants, which, during the summer/ autumn period, can contain 20% to 25% of their dry matter as salt. This study assessed the impact of coping with high dietary salt loads on the reproductive performance of grazing ewes. From the time of artificial insemination until parturition, 2-year-old maiden Merino ewes were fed either a high-salt diet (NaCl 13% of dry matter) or control diet (NaCl 0.5% of dry matter). Pregnancy rates, lamb birth weights, milk composition and the plasma concentrations of hormones related to salt and water balance, and energy metabolism were measured. Leptin and insulin concentrations were lower (1.4 6 0.09 v. 1.5 6 0.12 ng/ml; (P , 0.05) and 7.2 6 0.55 v. 8.2 6 0.83 ng/ml; P , 0.02) in response to high-salt ingestion as was aldosterone concentration (27 6 2.7 v. 49 6 5.4 pg/ml; P , 0.05), presumably to achieve salt and water homeostasis. Arginine vasopressin concentration was not significantly affected by the diets, but plasma concentration of T 3 differed during gestation (P , 0.02), resulting in lower concentrations in the high-salt group in the first third of gestation (1.2 6 0.18 v. 1.3 6 0.14 pmol/ml) and higher concentrations in the final third of gestation (0.8 6 0.16 v. 0.6 6 0.06 pmol/ml). T 4 concentration was lower in ewes ingesting high salt for the first two-thirds of pregnancy (162 6 8.6 v. 212 6 13 ng/ml; P , 0.001). No substantial effects of high salt ingestion on pregnancy rates, lamb birth weights or milk composition were detected.Keywords: aldosterone, high salt, insulin, leptin, reproduction IntroductionSalinity is an increasing problem in agriculture worldwide (Ghassemi et al., 1995) and the use of halophytic plants such as saltbush represents one of the few options available to revegetate salinised landscapes and re-establish grazing systems . Some landholders in Australia are grazing sheep on saltbush to fill a summer/ autumn feed gap (Masters et al., 2006), a period that coincides with the greater demands of late pregnancy for autumn-or winter-lambing ewes. However, feeding saltbush may possibly have a negative impact on reproductive performance of the ewes as high salt intake may reduce intake and cause physiological changes associated with adaptation to the salt load.High salt intake has been shown to reduce voluntary feed intake (Masters et al., 2005;Blache et al., 2007) as well as the efficiency of energy use for production (Arieli et al., 1989) in sheep. A decrease either in voluntary feed intake or in fat reserves is usually associated with a decrease in the concentration of metabolic hormones such as insulin and leptin (Chilliard et al., 2005) and recently a high salt ingestion has been shown by Blache et al. (2007) to affect energy metabolism through changes in insulin concentrations in sheep fed high salt (20% NaCl) diets. Thus, the ingestion of large amount of salt may impact energy availability and consequently reproductive performance.There are also physiological 'con...

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“…Insulin and GH were measured using the radioimmunoassays described by Tindal et al (1978). Concentrations of insulin and GH were expressed relative to the standards bovine insulin (24 i.u.lmg) and bovine GH (NIH-GH-B2; 1·5 U/mg) respectively.…”

Section: Plasma Hormonesmentioning

confidence: 99%

Local Intra-arterial Infusion of Growth Hormone into the Mammary Glands of Sheep and Goats: Effects on Milk Yield and Composition, Plasma Hormones and Metabolites

McDowell¹,

Hart²,

Ac³

1987

Aust. Jnl. Of Bio. Sci.

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Lactating goats and sheep were fitted with catheters in the external pudendal arteries supplying both mammary glands. Saline was infused continuously into one artery whereas the other artery received continuous infusions, over successive 4-day periods, of either saline or growth hormone (GH)-doses increasing twofold between successive periods from 100 to 400 ltg/day in goats and 400 to 3200 Itg/ day in sheep.Local infusion of GH at up to 1600 ltg/day in sheep did not affect milk yield or composition nor peripheral plasma concentrations of GH, insulin, glucose, urea and non-esterified fatty acids (NEFA). Infusion of GH at 3200 ltg/day in sheep increased peripheral plasma concentrations of GH, tended to increase milk yield and peripheral plasma NEF A but there were no changes in peripheral plasma insulin, glucose and urea. It is concluded that GH does not exert direct effects on the mammary glands of sheep and goats in situations where the hormone is administered over short periods.

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Release of Growth Hormone in Lactating and Non-Lactating Goats in Relation to Behaviour, Stages of Sleep, Electroencephalograms, Environmental Stimuli and Levels of Prolactin, Insulin, Glucose and Free Fatty Acids in the Circulation

Cited by 115 publications

References 0 publications

Follicle development, endocrine profiles and ovulation rate in adult Merino ewes: effects of early nutrition (pre- and post-natal) and supplementation with lupin grain

Follicle development, endocrine profiles and ovulation rate in adult Merino ewes: effects of early nutrition (pre- and post-natal) and supplementation with lupin grain

Reproductive capacity of Merino ewes fed a high-salt diet

Local Intra-arterial Infusion of Growth Hormone into the Mammary Glands of Sheep and Goats: Effects on Milk Yield and Composition, Plasma Hormones and Metabolites

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