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PubMed2006

Effects of pre- and postpartum nutrition on reproduction in spring calving cows and calf feedlot performance.

Crossbred, spring-calving cows (yr 1, n = 136; yr 2, n = 113; yr 3, n = 113) were used in a 3-yr experiment to evaluate the influence of supplemental protein prepartum and grazing subirrigated meadow postpartum on pregnancy rates and calf feedlot performance. A 2 x 2 factorial arrangement of treatments was used in a switchback design. From December 1 to February 28, cows grazed dormant upland range in 8 pastures (32 +/- 2 ha each). The equivalent of 0.45 kg of supplement/cow per d (42% CP) was provided to half of the cows on a pasture basis 3 d/wk. For 30 d before the beginning of breeding (May 1 to May 31), half of the cows grazed a common subirrigated meadow (58 ha), and the remainder was fed grass hay in a drylot. Cow BW and BCS were monitored throughout the year, and steer calf performance was determined until slaughter. Feeding supplement prepartum improved (P = 0.01 to P < 0.001) BCS precalving (5.1 vs. 4.7) and prebreeding (5.1 vs. 4.9) and increased (P = 0.02) the percentage of live calves at weaning (98.5 vs. 93.6%) but did not affect (P = 0.46) pregnancy rate (93 vs. 90%). Calves born to dams fed supplement prepartum had similar (P = 0.29) birth weight (37 vs. 36 kg) but greater (P = 0.02) weaning weight (218 vs. 211 kg). However, steer feedlot DMI (8.53 vs. 8.48 kg), ADG (1.6 vs. 1.6 kg), and carcass weight (369 vs. 363 kg) were not affected (P = 0.23 to P = 0.89) by prepartum supplementation. Allowing cows to graze subirrigated meadow postpartum improved (P < 0.001) BCS prebreeding (5.2 vs. 4.9) but did not affect (P = 0.88) pregnancy rate (92 vs. 91%). Allowing cows to graze subirrigated meadow increased (P = 0.01) calf weaning weight (218 vs. 211 kg) but not (P = 0.62 to P = 0.91) feedlot DMI (8.4 vs. 8.3 kg), ADG (1.6 vs. 1.6 kg), or carcass weight (363 vs. 362 kg) of their steer calves. Increased percentage of live calves at weaning as a result of feeding supplemental protein increased net returns at weaning and after finishing in the feedlot. Net returns were increased by allowing cows to graze subirrigated meadow postpartum regardless of whether calves were marketed at weaning or after finishing in the feedlot.

Animal Feed↗
PubMed1984

Kinetic differences between fed and starved Chinese hamster ovary cells.

When Chinese hamster (CHO-K1) cells are grown as monolayer cultures, they eventually reach a population-density plateau after which no net increase in cell numbers occurs. The kinetics of aged cells in nutritionally deprived (starved) or density-inhibited (fed) late plateau-phase cultures were studied by four methods: (i) Reproductive integrity and cell viability were monitored daily by clonogenic-cell assay and erythrosin-b dye-exclusion techniques. (ii) Mitotic frequencies of cells from 18 day old cultures were determined during regrowth by analysing time-lapse video microscope records of dividing cells. (iii) Tritiated-thymidine ([3H]TdR) autoradiography was used to determine the fractions of DNA-synthesizing cells in cultures entering plateau phase and during regrowth after harvest. (iv) The rate of labelled nucleoside uptake and incorporation into DNA was measured using liquid scintillation or sodium iodide crystal counters after labelling with [3H]TdR or [125I]UdR. Non-cycling cells in starved cultures accumulate primarily as G1 phase cells. Most cells not in G1 phase had stopped in G2 phase. Very few cells (less than 2%) were found in S phase. In contrast, about half of the cells in periodically fed cultures were found to be in DNA-synthetic phase, and the percentage of these S phase cells fluctuated in a manner reflecting the frequency of medium replacement. Populations of both types of plateau-phase cultures demonstrate extremely coherent cyclic patterns of DNA synthesis upon harvest and reculturing. They retain this high degree of synchrony for more than three generations after the resumption of growth. From these data it is concluded that nutritionally deprived (starved) late plateau-phase cells generally stop in either G1 or G2 phase, whereas periodically fed late plateau-phase cultures contain a very large fraction of cycling cells. Populations of cells from these two types of non-expanding cultures are kinetically dissimilar, and should not be expected to respond to extracellular stimuli in the same manner.

Animals↗
PubMed1997

Consideration of tissue response in the application of the two-mutation model to radiation carcinogenesis.

The Moolgavkar-Venzon-Knudson (MVK) two-mutation model of carcinogenesis is an analytical model that predicts the variation of cancer yield-rate with time, and with dose of a carcinogen. The model is biologically based, and assumes that a specific mutation in a stem-cell will increase its rate of proliferation compared with that of unmutated cells, so that a clone of pre-malignant cells develops; a second specific mutation in any one of these will make it malignant, and a cancer will start to grow. The model has been used in recent years to analyse a number of sets of epidemiological data on carcinogenesis. The purpose of this paper is to point to a problem in the use of this model for radiation-induced carcinogenesis, namely that ionizing radiation causes reproductive death of stem cells, which leads to regenerative division and hence a change in the number of stem-cells at risk. The possible effects of such changes on the predictions of the model are discussed. At low dose-rates of continuous or chronic irradiation and at low doses of acute irradiation, it is expected that pre-malignant cells will be killed along with the unmutated cells, and that the regenerative division of the surviving pre-malignant cells will restore the numbers of both stem cells and pre-malignant cells to what they would have been in the absence of cell killing; hence, no net effect of the tissue regeneration is expected. At high dose-rates, the initial delay in regenerative division and subsequent faster proliferation are expected to lead to an initial reduction in tumour yield-rate with time (compared with that predicted by the MVK model) followed by a faster increase. For acute irradiation, in the particular case of beta-particle irradiation of the skin, at high doses where there are practically no surviving cells in the irradiated area, repopulation by unirradiated cells from the margin is predicted to lead to a decrease in tumour yield-rate with dose. The predictions have been compared with published data on the induction of osteosarcoma in mouse by repeated injection of 89Sr, the induction of skin tumours in rat by acute and chronic irradiation with electrons, and the induction of skin tumours in mouse by acute irradiation with beta-particles. At low doses and dose-rates the basic MVK model fitted the data well. At higher doses and dose-rates the expected effects of tissue regeneration were observed qualitatively, although there were some discrepancies in detail; these are discussed.

Animals↗
PubMed2002

Providers of primary care to homeless women in Los Angeles County.

Little is known about the access barriers homeless women face at the sites where they are most likely to receive primary health care. To investigate this issue, we administered a mail survey to administrators and clinicians at clinic sites that were actual or potential providers of primary health care to homeless women in Los Angeles County in 1997. The response rate was 65%. Ninety percent of the homeless women seen by responding sites were seen at only 34% of those sites (designated as "major providers"). Deficiencies were identified in several structural and process characteristics that enhance access to and quality of care for homeless women, including clinician training in care for homeless persons; formal screening for homeless status and associated risk factors; and on-site provision of comprehensive health services, including mental health, substance abuse, reproductive health, and ancillary services. Some, but not all, deficiencies were less severe at major providers. Our results suggest that, although providers of care to homeless women share challenges faced by many safety net providers, there are several policy interventions that could improve access to and quality of care for homeless women.

Community Health Centers↗
PubMed1975

[Incorporation of a spiruline (Spirulina maxima) in swine food].

Two experiments on early weaned piglets and one experiment on sows during the first two reproductive cycles were made to determine the nutritive value of Spirulina maxima algae in the pig, taken as a "nutritional model" for man. The algae were introduced into the diets of the piglets, between 12 and 42 days of age, in a proportion representing 12 p. 100 of the total proteins. This level corresponded to 12 p. 100 algae in the first age feed (up to 21 days) in replacement of skim milk, and 8 p. 100 of the second age feed in replacement of soyabean meal. For the overall experimental period, from 12 to 42 days, the apparent digestibilities of the diets, measured by the chronium oxide marking, decreased by 6.9 and 6.1 points, respectively, for energy and total crude proteins as compared to the control diet. Replacement of the same raw materials by a soluble fish protein concentrate only led to a reduction of 2.9 and 3.5 points for energy and proteins. However, during the first week following weaning, the fish concentrate and spirulina gave identical results which were lower than those of the control (fig. 1). In spite of this lowering in the apparent digestibility the growths of the piglets were satisfactory and equivalent for all groups. Thus, the mĕtabolic utilisation of the fraction of feed absorbed was better for the spirulina group than for the control group, notably during the period between 12 to 21 days, although the supply of lysine in the spirulina group was 12 p. 100 lower (tab. VII). Consequently, this partially compensates for the low apparent digestibility of the algae in the young animal. For the female, the spirulina algaes were continously administered in a proportion of 5 p. 100 of the diet from a live weight of 75 kg. This did not change either the age or the weight at onset of puberty (tab IX). During the first reproductive cycle, the net weight gain of the sows receiving spirulina was lower than that of the control sows, but the number of piglets and the weight of the litter were higher (tab X). During the second cycle, performances were almost identical for the two groups, but piglets from the spirulina sows were slightly heavier than those from the control sows, in corelation with smaller litters (tab XI). During lactation, the lipid content of the milk was not substancially modified by addition of spirulina to the diet (tab. XIII). At the end of the two reproductive cycle the characteristics of the two groups of sows were identical, with a slightly higher culling rate for the spirulina group, but without direct relationship with the use of algae. Furthermore, the productivity of the sows was the same: 16.34 piglets weaned per sow and per year for the controls and 15.99 for the spirulina sows. Thus, if considering spirulina as a protein supplement to traditional proteins, its use in pig feeding does not seem to give rise to particular problem. However, it is advisable to restrict their supply to a level not exceeding 25 p...

Age Factors↗
PubMedDate not supplied

A management plan for the sport fishery of Parachromis dovii (Pisces: Cichlidae) in Hule lake, Costa Rica.

A first attempt to regulate the fishing activity while preserving the species and its habitats is presented for Hule lake. We intensively sampled the "guapote" between March 1996 and April 1997 using monofilament gill nets and a floating line, collecting 421 individuals. P. dovii biomass was relatively low; this species had a long life cycle (8-10 years) and the growth oscillation was low (C = 0.3). Maximum life expectation was estimated at 12 years and the point of minimum growth coincided with the spawning that takes place between November and December. After spawning, P. dovii take around seven months to reach recruitment size (54.6 mm). The length for sexual maturity was 134 mm Lt, which indicates that this species is viable for reproduction soon after leaving the protection zones around the lagoon. "Guapote" sport fishing in the Hule lake is in equilibrium, the renewal rate is 80%. An increment in the actual fishery effort is not recommended, since it could seriously affect the natural renewal capacity of the stock.

Animals↗
PubMed1998

Evaluation of timed insemination during summer heat stress in lactating dairy cattle.

We wished to compare the effect of summer heat stress on pregnancy rate in cows that were inseminated at a set interval associated with a synchronized ovulation vs those inseminated upon routine estrus detection. The study was carried out on a commercial dairy farm in Florida from May to September 1995. Lactating dairy cows were given PGF2 alpha (25 mg i.m.) at 30 + 3 d postpartum and randomly assigned to be inseminated at a set time (Timed group) or when estrus was detected (Control group). Cows in the Timed group were synchronized by sequential administration of Buserelin (8 micrograms i.m.) on Day 0 at 1600 h, PGF2 alpha (25 mg i.m.) on Day 7 at 1600 h and Buserelin (8 micrograms i.m.) on Day 9 at 1600 h. They were inseminated on Day 10 between 0800 and 0900 h (Day 9 + 16 h). Cows in the Control group were given PGF2 alpha at 57 + 3 d postpartum and inseminated when detected in estrus. Estrus detection or insemination rate for control insemination cows was 18.1 +/- 2.5% versus 100% for time inseminated cows (P < 0.01). Mean interval from PGF2 alpha to insemination was shorter for time inseminated cows (3 +/- 2.1 d < 35.5 +/- 1.9 d; P < 0.01). Pregnancy rate was greater for time inseminated cows (13.9 +/- 2.6 > 4.8 +/- 2.5%; P < 0.01) as was overall pregnancy rate by 120 d postpartum (27.0 +/- 3.6 > 16.5 +/- 3.5%; P < 0.05). Number of days open for cows conceiving by 120 d postpartum was less for time inseminated cows (77.6 +/- 3.8 < 90.0 +/- 4.2 d; P < 0.05), as was interval to first service (58.7 +/- 2.1 < 91.0 +/- 1.9 d; P < 0.01). Services per conception were greater for time inseminated cows (1.63 +/- 0.10 > 1.27 +/- 0.11; P < 0.05). The timed insemination program did improve group reproductive performance. However, the timed insemination program will not protect the embryo from temperature-induced embryonic mortality, but management limitations induced by heat stress on estrus detection are eliminated. An economical evaluation of the timed insemination program indicates an increase in net revenue per cow with implementation of timed insemination for first service during the summer months.

Animals↗
PubMed1997

Effect of the plant Azolla pinnata on survival, growth rate, fecundity and hatchability of egg-masses of Biomphalaria alexandrina snails.

Data indicated that Azolla pinnata plants variously reduce the growth rate of Biomphalaria alexandrina snails expressed as net increase in shell diameter (direct or indirect exposure). The plant density played an important role in this respect. The higher the plant density was the lower the growth rate and vice versa. Too, indirect exposure of newly hatched B. alexandrina resulted from exposed treated eggs reduced the growth rate of these snails. Data revealed that direct and/or indirect exposure to the abnormal high density (50,000 plants/L) resulted in complete kill of B. alexandrina snails after two weeks from continuous exposure. Snails exposed directly to Azolla at 50,000 and 25,000 plants/L failed to lay eggs. On the other hand, sanils exposed to 10,000 plants/L laid few eggs, resulted in low reproductive rate (57.94) compared with unexposed ones (110.6). The same trend of results was recorded with hatchability of Biomphalaria eggs.

Animals↗
PubMedDate not supplied

Batflies parasitic on some phyllostomid bats in southeastern Brazil: parasitism rates and host-parasite relationships.

Ectoparasitic batflies were studied on 12 species of phyllostomid bats, by making 35 nightly collections of bats using mist nets at the "Panga" Ecological Reservation near Uberlândia, State of Minas Gerais, southeastern Brazil, from August 1989 to July 1990. Eleven species of Streblidae and one of Nycteribiidae were collected on 12 species of bats. Prevalence of ectoparasitic flies was lower than those reported by other authors for the New World and may be the result of the lack of caves in the study area, causing bats to roost in less favorable locations, forming smaller colonies. The fly, Trichobius joblingi Wenzel, was found on Carollia perspicillata (Linnaeus), showing preference for adult male bats. This could be explained by the predominance of males in the bat colonies, and by the fact that females rest in isolation during the reproductive period making them less exposed to the parasites. The streblid flies, Aspidoptera falcata Wenzel and Megistopoda proxima (Séguy), were found on Sturnira lilium (Geoffroy). A. falcata occurred mainly on young and adult females, whereas M. proxima did not show any preferences relative to the reproductive condition of the host. Ecological factors are important in determining differential numbers of parasites occurring on the different sexes, ages and reproductive state of the hosts.

Age Factors↗
PubMed2003

Unmet need and unintended fertility: longitudinal evidence from upper Egypt.

CONTEXT: Although unmet need for family planning is a standard measure for evaluating programs' effectiveness in meeting the reproductive needs of individuals, its validity and accuracy in identifying women most at risk of unintended pregnancy have been questioned. METHODS: Women who participated in the 1995 Egypt Demographic and Health Survey in two governorates in Upper Egypt (Assuit and Souhag) were followed for two years (N=2,444); in-depth data on their fertility preferences, contraceptive use and births were gathered in 1996 and 1997. Transitions among contraceptive need categories from 1995 to 1997 are examined, and rates of unintended (mistimed and unwanted) births are calculated according to contraceptive need status at baseline. RESULTS: In the aggregate, unmet need increased by six percentage points, from 28% to 34%. This change was the net outcome of 14% moving out of unmet need and 20% moving into unmet need (i.e., substantial satisfaction of unmet need was offset by increased demand for contraception). The rate of unintended fertility was far higher among women with unmet need at baseline than among contraceptive users in 1995. Women with unmet need made up about one-quarter of the baseline sample, but they contributed almost one-half of mistimed and unwanted births during the two years. The majority of unintended births were to women who had never practiced contraception, whereas fewer than one-fifth were to women with recent contraceptive experience (including contraceptive failure). CONCLUSIONS: : Unmet need for family planning remains a useful tool for identifying and targeting women at high risk of unintended pregnancy.

Contraceptive Agents↗
PubMed1991

Comparison of Booroola Merino and Finnsheep: effects on productivity of mates and performance of crossbred lambs.

Booroola Merino (BM) and Finnsheep (FS) rams were mated to FS and crossbred (CO) ewes to compare their effects on the productivity of their mates and the performance of their progeny. Effects of breed of ram and the interaction of breed of ram X breed of ewe were no significant for fertility, total number born, number born alive, litter birth weight, or number of lambs weaned by the ewe or in the nursery. Birth weights of FS- and BM-sired lambs were equal, but FS-sired lambs were heavier at weaning and 147 d of age. Compared with BM-sired lambs, survival from birth to weaning of dam-reared lambs was greater for FS-sired lambs produced by CO dams than for FS-sired lambs produced by FS dams. At a constant live weight, FS-sired lambs had a heavier carcass with less external fat thickness than BM-sired lambs. Percentage of ewe lambs reaching puberty was lowest and age at puberty was highest for the BM X CO cross; relatively small differences existed between the other three genotypes for these traits. Ewe lambs sired by BM had a greater ovulation rate than FS-sired ewe lambs. Embryo mortality was greater in BM X CO ewe lambs than in ewe lambs of the other three genotypes; the difference was larger for ewes with three ovulations than for ewes with two ovulations. The net result was that BM X CO ewe lambs averaged slightly fewer lambs born than FS X CO ewes. The BM X FS ewe lambs had larger litters than the FS ewes due to a substantially higher ovulation rate and only a slightly lower overall embryo survival rate. With the exception of ovulation rate and litter size, FS rams produced lambs with a more desirable level of performance than did BM rams.

Animals↗
PubMed1993

No reason for complacency about the potential demographic impact of AIDS in Africa.

Much uncertainty surrounds the likely demographic impact of AIDS in the worst afflicted regions of the developing world such as sub-Saharan Africa. Various research groups have published projections of future trends but these differ widely with respect to potential impact on net population growth rates. Pessimistic forecasts suggest that AIDS may reverse the sign of a 3% to 4% population growth rate before the establishment of HIV, over time periods of a few to many decades. Optimistic forecasts suggest a decline in population growth rates, but predict that a 3% growth rate before AIDS may be reduced by only about 50% over a period of a few decades. This paper reports new analyses of the demographic impact of AIDS, based on observed age-stratified prevalences of HIV-1 infection amongst women of child bearing age. It is assumed that the observed patterns reflect the final endemic state and the implications of this assumption for adult and infant mortality and female reproductive life expectancy are assessed. It is concluded that a variety of scenarios is possible, depending on the detail of assumptions concerning life expectancy before the arrival of AIDS, the incubation period of the disease, and the rate of vertical transmission. Realistic assumptions do suggest, however, that the observed prevalences of infection in the worst afflicted regions of sub-Saharan Africa are sufficient to reduce current population growth rates to close to, or below, zero in the coming decades.

Adolescent↗
PubMed2006

A rapid neuromodulatory role for steroid hormones in the control of reproductive behavior.

The long-term transcriptional actions of steroids that shape neuronal morphology and the probability of behavioral expression are well established. More recently, attention has been focused on the role of rapid (minute-by-minute) steroid actions on neuronal mechanisms of reproductive behavior. In this review, we first consider the rapid actions of steroids on mating and copulatory behaviors in tetrapod vertebrates. Evidence for rapid effects of steroids is presented for chemoinvestigatory behavior (genital sniffing of females by male mice), lordosis (arched-back mating posture in female rats), copulatory mounting (male mice and male Japanese quail), reproductive clasping (pre-copulatory mounting in newts), and paced mating (copulation rate as determined by female rats). We then review recent studies in teleost fish that demonstrate the rapid actions of steroids on vocal patterning at two levels: (1) central pattern generators and (2) social behavior in natural environments. Thus, we propose that steroid-dependent modulation of central pattern generators can govern the overt expression of reproductive behaviors via rapid non-transcriptional mechanisms that are likely to be widespread among vertebrates.

Animals↗
PubMed1994

Progestogen-only contraceptives during lactation: I. Infant growth. World Health Organization Task force for Epidemiological Research on Reproductive Health; Special Programme of Research, Development and Research Training in Human Reproduction.

Growth, development and health of infants whose mothers used progestogen-only contraceptives during lactation were examined in a prospective, non-randomized study carried out in seven centres in five countries (Egypt, Thailand, Kenya, Chile and Hungary). The results on growth are reported here. Breastfeeding women requesting effective contraception were admitted to the study at six weeks postpartum. Infants of acceptors of progestogen-only methods (pill, DMPA, NET-EN or NORPLANT implants) and non-hormonal methods (IUD, barrier methods or sterilization) formed the study groups. The follow-up was at monthly intervals until the end of the first postpartum year. Participating in the study were 2466 mother-infant pairs. The mean duration of exclusive breastfeeding varied from 68 to 159 days, but did not differ significantly between study groups within centres. In anthropometric measures (weight, arm circumference and triceps skinfold), the mean rates of change varied over time as expected, and across the centres. However, there were very few statistically significant differences in these rates of change between groups within centres. Since a large number of statistical comparisons were made, and there was no consistency either across centres, over time, or in the direction of the differences, we conclude that in this study, the progestogen-only contraceptives used during lactation did not adversely affect infant growth.

Adolescent↗
PubMed2005

Reinterpretation of gizzard sizes of red knots world-wide emphasises overriding importance of prey quality at migratory stopover sites.

The size of digestive organs can be rapidly and reversibly adjusted to ecological circumstances, but such phenotypic flexibility comes at a cost. Here, we test how the gizzard mass of a long-distance migrant, the red knot (Calidris canutus), is adjusted to (i) local climate, (ii) prey quality and (iii) migratory fuelling demands. For eight sites around the world (both wintering and stopover sites), we assembled data on gizzard masses of free-living red knots, the quality of their prey and the local climate. Using an energetic cost-benefit approach, we predicted the gizzard size required for fastest fuelling (net rate-maximization, i.e. expected during migration) and the gizzard size required to balance daily energy budgets (satisficing, expected in wintering birds) at each site. The measured gizzards matched the net rate-maximizing predictions at stopover sites and the satisficing predictions at wintering sites. To our surprise, owing to the fact that red knots selected stopover sites with prey of particularly high quality, gizzard sizes at stopovers and at wintering sites were nevertheless similar. To quantify the benefit of minimizing size changes in the gizzard, we constructed a model incorporating the size-dependent energy costs of maintaining and carrying a gizzard. The model showed that by selecting stopovers containing high-quality prey, metabolic rates are kept at a minimum, potentially reducing the spring migratory period by a full week. By inference, red knots appear to time their stopovers so that they hit local peaks in prey quality, which occur during the reproductive seasons of the intertidal benthic invertebrates.

Animals↗
PubMed1996

Improved performance of a large pig complex after sequential nursery depopulation.

An attempt was made to compare the productivity and financial benefits of nursery depopulation on five large pig farms which were all part of one complex. Each farm had been experiencing poor post weaning performance for 12 months, and had previously been infected with porcine reproductive and respiratory syndrome virus (PRRSV). A plan to depopulate each nursery sequentially was established, and the pigs were moved to fattening facilities on one of the farms (farm 3) where space was available. Over a four week period, the nurseries of farms 1, 2, 4 and 5 were emptied, cleaned and disinfected, and any changes in nursery performance, mortality and the seroprevalence of antibodies to PRRSV were then assessed for one year. The financial benefit to the entire farm complex was analysed by using partial budget methods. During the year a net benefit of $1,708,431 was assessed to the farm complex owing to the increased numbers of marketable pigs and the reduced antibiotic costs. There were highly significant improvements in nursery growth rate and decreases in mortality on farms 1, 2, 4 and 5, and antibodies to PRRSV were detected on farms 3 and 4 but not on farms 1, 2 and 5. The inability to empty the farm 3 fattening facility, which housed the pigs from the other sites, may have led to the maintenance of its PRRSV positive status and could have served as the source of virus for farm 4.

Animal Husbandry↗
PubMed1983

Prednisolone disposition and protein binding in oral contraceptive users.

Combined estrogen-progestogen oral contraceptives (OC) have been shown to alter the metabolism of certain drugs, including corticosteroids, as well as affect circulating protein concentrations. To assess these effects with regard to prednisolone, the pharmacokinetics and protein binding of this steroid were evaluated in eight female OC users and compared with results from eight male and five female non-OC users. All volunteers received 40 mg prednisolone, iv, and steroid concentrations were measured by high pressure liquid chromatography. Plasma clearance of total prednisolone in females on OC was 96 +/- 9 (SD) ml/min X 1.73 m2, significantly (P less than 0.001) lower than those in both male and female controls (205 +/- 46 and 187 +/- 22 ml/min X 1.73 m2). The prednisolone half-life and mean residence time were longer, while the steady state volume of distribution was smaller for OC users. Unbound prednisolone was measured by equilibrium dialysis, and pharmacokinetic and protein binding parameters were calculated from free prednisolone concentrations. A significantly higher (2-fold) concentration of transcortin was found in OC users. Evaluation of free prednisolone parameters showed a significantly lower clearance and decreased volume of distribution, without alteration of the mean residence time for the OC users. Dual OC effects on binding and elimination of prednisolone occur with the net result of a 2-fold increase in the area under the free concentration-time curve, indicative of a marked reduction in the biotransformation rate of the steroid.

Adult↗
PubMed1988

Economic and reproductive consequences of retained placenta in dairy cattle.

The financial losses due to retained placenta in Dutch dairy cattle were estimated by using two different methods of calculation. A data-set containing the birth records of 160,188 Meuse-Rhine-Yssel cows provided data on the reproductive performance of cows with and without retained placenta. The fertility of cows after retention of the placenta appeared to be affected. An economic calculation made by adding the losses due to increased calving interval, increased culling rate, loss of milk production and the costs of veterinary treatment and drugs revealed that the total loss due to retained placenta was 471 pounds per year for a 100-cow farm with an average incidence of the condition (6.6 per cent). For a 'problem' farm with a 30 per cent rate, the loss was 2139 pounds per year. A computer farm simulation model, based on a stochastic determination of events, was used to make calculations for circumstances closely resembling those on farms. A 6.6 per cent rate of retained placenta caused a small but significant decrease in net return on labour and management; however, a 30 per cent rate caused highly significant changes. The economic effects of retained placenta were similar in magnitude in herds of high or low productivity and high or low fertility. Sensitivity analysis showed that the greatest financial losses were caused by loss of milk production, followed by the number of animals suffering from complications. The financial losses in herds with an average rate of retained placenta were thus of limited economic importance and therapeutic measures alone should be adequate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Husbandry↗