Sheep hormones

Crystals. Isoelectric point 5.73. [a]p — 40.5 (c — I in phosphate buffer of pH 7). Practically insol in water (0.102 g/l) unless electrolytes are present. Forms a water-soluble hydrochlorida. Sol in abs methanol or ethanol, if a small amount of acid is present. These data apply to prolactin obtained from ox glands. Prolactin from sheep glands is slightly different In 0.357M NaCl at pH 2.25 the sheep hormone has a soly of 0.506 g/l. while the soly of the ox hormone is only 0.316 g. In citrate butter (1M, pH 6.36) and in alcohol the ox protein is more sol than the sheep protein. In the absence of salt, prolactin shows little loss of... 

The luteinizing hormone has been prepared from the same sources. Again, the molecular weight varies from sheep (40,000) to swine (100,000) but in this case the sheep hormone has the lowest molecular weight. LSH is also a glycoprotein, and hexosamine... 

In the early 1930 s, when the prime research aim was the commercial synthesis of the sex hormones (whose structures had just been elucidated), the principal raw material available was cholesterol extracted from the spinal cord or brain of cattle or from sheep wool grease. This sterol (as its 3-acetate 5,6-dibromide) was subjected to a rather drastic chromic acid oxidation, which produced a variety of acidic, ketonic and hydroxylated products derived mainly by attack on the alkyl side-chain. The principal ketonic material, 3j -hydroxyandrost-5-en-17-one, was obtained in yields of only about 7% another useful ketone, 3 -hydroxypregn-5-en-20-one (pregnenolone) was obtained in much lower yield. The chief acidic product was 3j -hydroxy-androst-5-ene-17j -carboxylic acid. All three of these materials were then further converted by various chemical transformations into steroid hormones and synthetic analogs ... 

The advantages of recombinant DNA technology are enormous, as the following example shows. Somatostatin is a hormone that inhibits the secretion of pituitary growth hormone. The researchers who first isolated somatostatin required nearly half a million sheep brairrs to produce 5 mg of the substance. Using a chemically synthesized gene, 9... 

The influence of gonadal hormones on prepubertal animals suggests some steroidal sensitivity in adults with regard to F. elicitation. Young male sheep are induced to perform F. in response to exogenous T and to 17-p-estradiol F. in female red deer is also sensitive to T injections (Parrott, 1978 Fletcher, 1978). Sex differences can interact with the hormonal state where social conditions vary. Female cats (intact) display F. to urine marks only in the absence of males testosterone propionate induced F. in spayed females towards estrous females (Verbeme, 1976 Hart and Leedy, 1987), whereas an ovarian hormone (estradiol) failed to elicit F. to males (intact, and sexually inactive), presumably indicative of social inhibition overriding steroid facilitation. 

After exerting their action in the organism, natural and synthetic hormones are catabolized in the liver by conjugation to glucuronide and/or sulfate moieties, forming more polar conjugated forms which are excreted via urine. This is the main route of hormone excretion in humans and pigs. A fraction of hormones is also excreted in a free form via feces in animals such as sheep and cattle this is the main route for hormone excretion (Table 3) [66, 67],... 

EPO is present in serum and (at very low concentrations) in urine, particularly of anaemic individuals. This cytokine/hormone was first purified in 1971 from the plasma of anaemic sheep, and small quantities of human EPO were later purified (in 1977) from over 2500 1 of urine collected from anaemic patients. Large-scale purification from native sources was thus impractical. The isolation (in 1985) of the human EPO gene from a genomic DNA library facilitated its transfection into CHO cells. This now facilitates large-scale commercial production of the recombinant human product (rhEPO), which has found widespread medical application. 

Estradiol subsequently builds up in the blood and first (within 2 to 12 hours) reduces the levels of follicle-stimulating hormone (FSH) and the amplitude of LH pulses, then (within 12 to 48 hours) causes preovulatory surges of LH and FSH. The former promotes ovulation and development of a corpus luteum (reviewed in Martin et ah, 1986). Two compounds have been indicated in the effect of the odor of ram s fleece on LH secretion in anestrous ewes. These are 1,2-hexadecanediol and 1,2-octadecanediol. In Merino sheep at least, maximum stimulation of ovulation requires full exposure to a ram, such as fenceline contact in pastures. Olfactory cues from the ram s wool, presented in a facemask for the ewe, are ineffective by themselves visual and tactile stimuli are also important. The Merino breed does not rely as much on olfactory cues as other breeds of sheep (Pearce and Oldham, 1988). The effect is not necessarily species specific hair extract from male goats stimulates LH release in ewes. For this effect, the accessory olfactory system is not necessary (Signoret etah, 1989). 

In Australia, lambing in sheep has dropped to as little as 30% after grazing on subterranean clover. Trifolium subterraneum. The clover contains the isoflavonoids formononetin and genistein (Fig. 11.11). These compounds mimic the steroidal nucleus of the natural female hormone estrone. Alfalfa, M. sativa, and ladino clover. Trifolium repens, contain the even more potent isoflavonoid coumestrol. It is 30 times more active than genistein or formononetin, but occurs in lower concentrations in the plant (Shutt, 1976). 

Paul C., S.M. Rhind, C.E. Kyle, H. Scott, C. McKinell, and R.M. Sharpe (2005). Cellular and hormonal dismption of fetal testis development in sheep reared on pasture treated with sewage sludge. Environmental Health Perspectives 113 1580-1587. 

These beneficial effects, which are on the order of 10-40%, are achieved predominantly in ruminants. It has been estimated that use of hormonal implants can improve farmers margins by up to 30 a head for steers and 15 a head for heifers. Applications in other food-producing animals such as sheep, swine, and poultry occur to a lesser extent and, thus, are of limited importance. 

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