PubMed Health⌕ Search

Biomedical subjects

W R Butler

Publications and source records attributed to W R Butler.

At least 109 records · Page 6Linked to original sources
PubMed1981

The relationships between energy balance, milk production and ovulation in postpartum Holstein cows.

Energy balance and serum progesterone concentrations were monitored during early lactation in a group of high producing Holstein cows. The postpartum interval to normal ovulation averaged 36 +/- 6 days (range 6 to 83 days). Average energy balance during the first 20 days of lactation (cumulative daily calculated energy balance divided by days in milk) was inversely related to days to normal ovulation (r = -.60) and to milk production (r = -.80). Milk yield during this period was not closely related to days to ovulation (r = .30). Milk yield was also not significantly related to serum prolactin concentrations over the first 12 weeks of lactation (r = .27). During early lactation, energy balance was maximally negative until peak milk yield and then began returning toward zero, with the magnitude and duration of negative energy balance being quite variable. On the average, ovulation and the initiation of the first normal luteal phase occurred approximately 10 days after energy balance began returning toward zero. During this 10-day interval, a transient elevation in serum progesterone concentrations occurred in eight of 13 cows. These results suggest that energy balance during the first 20 days of lactation is important in determining the onset of ovarian activity following parturition.

Animals↗
PubMed1981

The relationship between breed and litter size in sheep and maternal serum concentrations of placental lactogen, estradiol and progesterone.

Milk production in sheep is known to be affected by breed and litter size. To investigate a possible hormonal basis for such effects, we measured maternal serum concentrations of placental lactogen, estradiol and progesterone during late gestation in sheep of several breeds and ages. Circulating concentrations of placental lactogen were directly related to litter size in all breeds, with the greatest concentrations being observed in Finnish Landrace ewes bearing three lambs. Among monotocous animals, no significant breed differences were observed, but ewe lambs bearing crossbred fetuses had higher placental lactogen concentrations than ewes of the same breed carrying purebred offspring. Placental lactogen concentrations were similar in all animals bearing twins, except for Corriedale ewes, which had the lowest concentrations. Serum estradiol concentrations 2 to 5 weeks prepartum did not differ between ewes of different breeds or ewes with different litter sizes. Progesterone, like placental lactogen, was related to litter size and, presumably placental mass. The relationship between litter size and placental lactogen concentrations, together with the absence of difference in estradiol secretion, suggests that differences in production of the lactogenic hormone may contribute to the superior lactational performance that has been reported for ewes which bear multiple offspring.

Animals↗
PubMed1981

Effect of adrenocorticotropin on milk and plasma cortisol and prolactin concentrations.

Milk cortisol and prolactin concentrations were measured in 12 lactating Holstein cows for 3 days (Experiment 1). On day 3, cows were divided randomly into groups: IV1, IV4, IM, and control. Group IV1 received one intravenous injection of 49 IU adrenocorticotropin, group IV4 the same dosage four times at 2-h intervals, group IM 240 IU adrenocorticotropin intramuscularly, and control cows were injected with saline. Cortisol concentrations in blood plasma were increased in all groups following adrenocorticotropin injection, while milk cortisol concentrations increased fourfold in groups IV4 and IM and remained unchanged in group IV1. In Experiment 2, infusion of 18% saline into the mammary gland of three cows increased the somatic cell count in the infused quarter but had no effect on prolactin and cortisol of milk or plasma. In Experiment 3, six cows each were assigned to treatment groups of saline controls, IV2-0 (40 IU adrenocorticotropin intravenously at 0 and 2 h post-milking) or IV2-8 (40 IU adrenocorticotropin intravenously at 8 and 10 h post-milking). Half udders of each cow were milked before treatment and 4 h later. Increases of cortisol in plasma increased cortisol concentrations of milk 4 h after each treatment (IV2-0 and IV2-8). However, by 12 h after treatment in IV2-0 cortisol concentrations of milk had returned to normal. Increases in adrenal cortisol secretion are followed rapidly (within 4 h) by increased cortisol concentrations in milk. However, these decline rapidly in the absence of sustained increments in blood cortisol. Increased cortisol concentrations in milk most likely represent sustained elevation in plasma cortisol.

Adrenocorticotropic Hormone↗
PubMed1981

Rapidity of cortisol transfer between blood and milk following adrenocorticotropin injection.

Cortisol concentrations in milk and blood plasma were measured in 12 lactating Holstein cows following administration of 40 IU adrenocorticotropin intravenously (groups 1 and 2) or 4 ml saline (control). Blood and milk samples were collected at 15 or 30-min intervals for 4 h from control and group 1 cows and at hourly intervals for 4 h from group 2. Cortisol concentrations in plasma and milk were increased 15 min after treatment and peaked by 1 h in group 1 but remained unchanged in controls. Group 2 cows were sampled less frequently but showed a pattern for plasma and milk cortisol concentrations similar to group 1. The profile of increased cortisol concentrations and of their decline 1 to 2 h later was similar for plasma and milk. These results suggest that cortisol concentrations in milk reliably indicate cortisol concentrations in blood and may be valuable in monitoring stress in dairy cows, depending upon duration of stress and its timing relative to milk removal.

Adrenocorticotropic Hormone↗
PubMed1980

Radioimmunoassay technique for measuring cortisol in milk.

A sensitive radioimmunoassay procedure for measurement of cortisol has been developed for use in whole or skim milk. Cortisol concentrations were similar in whole and skim milk indicating that this steroid is not associated with milk lipids. Because of this relationship, the use of skim milk provides a faster and much simplified approach to the study of cortisol in milk. Mean and standard errors of cortisol concentrations in skim milk samples collected at 2400 and 1200 h from seven cows for 1 wk were .71 +/- .05 and .69 +/- .07 ng/ml. Cortisol in colostrum averaged 1.59 +/- .07 ng/ml.

Animals↗
PubMed1976

Periparturitional serum concentrations of prolactin, the gonadotropins, and the gonadal hormones in the rhesus monkey.

The time courses of serum concentrations of prolactin, estradiol, estrone, progesterone, LH, and FSH were studied in seven pregnant rhesus monkeys from 1 month prior to delivery until 1 month after parturition. All animals nursed their young. Circulating levels of estradiol and estrone increased during the last few days of pregnancy, reaching peak values of 700 pg/ml and 350 pg/ml, respectively, on the day prior to delivery, fell precipitously to about 25 pg/ml within 1 day after parturition, and remained at this level for at least 30 days. Serum prolactin concentrations also increased during the week preceding parturition, rose abruptly at delivery, and then declined gradually. Serum progesterone levels ranged between 2 and 3 ng/ml during the last month of pregnancy, rose slightly a few days prior to parturition, decreased sharply at delivery to 50% of prepartum levels and declined gradually thereafter. Serum LH and FSH levels were not detectable during the entire sampling period. The administration of estradiol benzoate to two pregnant monkeys at midgestation, in a manner which replicated the normal prepartum increase in serum estradiol concentrations, failed to elicit an elevation in circulating prolactin levels or to induce premature delivery of the fetus.

Animals↗
PubMed1975

Surgical disconnection of the medial basal hypothalamus and pituitary function in the rhesus monkey. I. Gonadotropin secretion.

In an intial attempt to localize the central components of the neuroendocrine control systems whereby estrogens regulate gonadotropin secretion, the medial basal hypothalamus (MBH) was surgically isolated from the remainder of the brain in 18 female rhesus monkeys using a modified "Halasz knife". The completeness and localization of the resulting "cuts" were verified by examinations of serial 50 mugM coronal sections through each hypothalamus. The cuts extended from the optic chiasm to the mamillary bodies and from midline to the medial aspects of the optic tracts. The MBH "ISLANDS" ISOLATED BY THESE CUTS INCLUDED THE MEDIAN EMINENCE AND ARCUATE NUCLEI AS WELL AS PORTIONS OF THE VENTROMEDIAL NUCLEI, PREMAMILLARY AREAS AND MAMILLARY BODIES. Following complete MBH isolation, 6 of 7 otherwise intact monkeys responded to an estradiol benzoate (EB) injection with large LH and FSH surges. Three of these animals also displayed spontaneous gonadotropin surges which eventuated in ovulation as evidenced by sustained elevations in circulating progesterone levels. Similar patterns of LH and FSH secretion in response to EB administration were also observed in 6 of 7 intact animals in which only the superofrontal imputs to the MBH WERE INTERRUPTED. Four of these monkeys ovulated spontaneously. Circulating gonadotropin levels fell slightly in ovariectomized monkeys following complete MBH disconnection, but the circhoral, pulsatile rhythms of gonadotropin release persisted. These animals also responded to the negative and positive feedback actions of estrogen as evidenced by initial declines in circulating LH and FSH concentrations followed by surges of these hormones at the appropriate times following the injection of EB. It would appear from these observations that the sites of the negative and positive feedback actions of estrogen on LH and FSH secretion and, therefore, the sites of the central components of the neuroendocrine systems which control tonic and surge secretion of the gonadotropic hormones in the rhesus monkey may be resident within the MBH-hypophysial unit.

Animals↗
PubMed1975

Surgical disconnection of the medial basal hypothalamus and pituitary function in the rhesus monkey. III. Thyroxine secretion.

The effects of complete and anterior disconnection of the medial basal hypothalamus (MBH( on TSH secretion in the rhesus monkey were assessed by measuring serum thyroxine concentrations. Following complete MBH disconnection, serum thyroxine concentrations declined to 50% of preoperative control levels within 7 days. In 6 of 10 animals, thyroxine levels remained depressed throughout the postoperative observation period of 60 to 150 days. In the remainder, serum thyroxine concentrations returned to control levels after 3 weeks. Anterior disconnection of the MBH had variable effects on thyroid function. In 4 of 7 animals, serum thyroxine concentrations declined for 5 days following the operation but returned to preoperative levels within the next 3 weeks. In 2 others, serum thyroxine levels did not change while in the remaining animal thyroxine concentrations increased transiently to twice preoperative levels before returning to normal values. Thus, in the monkey, as in the rat, anterior MBH disconnection has little consistent effect on thyroid function, while complete isolation of the MBH causes a moderate decline which is most readily attributable to a decrease in thyrotropin secretion. The variations in the effects of anterior and complete MBH disconnection on thyroid function could not be confidently correlated with variations in the placement of the cuts.

Animals↗
PubMed1975

Functional luteolysis in the rhesus monkey: ovarian estrogen and progesterone during the luteal phase of the menstrual cycle.

In a continuing effort to elucidate the processes underlying in primates, the concentrations of estradiol, estrone and progesterone were measured in ovarian tissues and in ovarian vein plasma through the luteal phase of the menstrual cycle of the rhesus monkey. The concentration of progesterone in corpora lutea collected 4-6 days after the preovulatory LH peak (early luteal phase) was more than twice that found in those collected 8-13 days after the LH surge (late luteal phase) while estradiol and estrone concentrations in the latter had increased 4-fold. These changes in luteal steroid concentrations were paralleled by a striking increase in the concentration of estrone in the ipsilateral ovarian vein. Estrone predominated in the venous effluent of the ovary beaing the corpus luteum while estradiol concentrations were similar in both ovarian veins suggesting that estrone is the principal estrogen released by the corpus luteum. The results of this study are consonant with the hypothesis that estrogen produced by the corpus luteum is the physiologic luteolsin in the rhesus monkey.

Animals↗