Effects Of Reproductive Status Research Articles

Effect of reproductive status on plasma oxytocin concentrations and the renal response to oxytocin in the conscious rat

Effect of reproductive status on plasma oxytocin concentrations and the renal response to oxytocin in the conscious rat

The effects of physiological state on the carcass composition of continental heifers

Several studies have investigated once-bred heifers as a means of improving the efficiency of beef production. In these studies, when compared with unbred heifers, the observed carcass effects were usually associated with simultaneous changes in several factors namely: diet composition, plane of nutrition, carcass weight and age at slaughter. The present study aimed to examine the effects of reproductive state on carcass weight and carcass composition, with bred and unbred heifers grown at equal rates of carcass gain on diets of equal composition.

Effect of reproductive state and concentrate supplementation on liquid and particulate turnover in the rumen of ewes given ammonia treated straw

Rates of passage of liquid and particulate markers (Co-EDTA, Cr mordanted fibres and Yb) were measured in ewes at late pregnancy, lactation and non-breeding status. Animals were given ammonia treated barley straw ad libitum supplemented daily with 250 and 550 (pregnancy), 550 and 850 (lactation) and 250, 550 and 850 (non-breeding) g of concentrate. The effect of the reproductive state was analysed only on ewes fed on 550 g of concentrate. Lactating ewes showed a higher voluntary straw intake (970 g/day) than pregnant or non-breeding ewes (720 and 790 g/day respectively), but there were not significant differences in the OM digestibility (OMD) among reproductive states. Increasing concentrate supplementation promoted significant decreases in the voluntary intake of straw, associated with an enhanced OMD ( P < 0.05). Fractional outflow rates (FOR/h) were higher in pregnant and non-breeding than in lactating ewes, although differences were only significant ( P < 0.01) for Chromium derived values. Ewes given 250 g of concentrate showed lower ( P < 0.05) FOR than those given 550 and 850 g/day. Results support the idea that in ruminants fed on low quality roughages, voluntary dry matter intake is mainly restricted by rumen capacity, although the energy status of the animals might influence the extent of this restriction.

Consequences of reproduction on the liveweight, fat depth, wool growth, and intake of grazing Merino ewes in the short and long term

Effects of the current and previous year's reproductive performance on liveweight, fat depth, pasture intake, and wool growth were estimated in breeding Merino ewes in each of 2 years and in 4 seasons corresponding with stages of the annual reproductive cycle. Ewes bearing multiple lambs were heavier in early pregnancy (autumn, by 1.5 kg) and in late pregnancy (winter, by 2.5 kg) than single-bearing ewes, with both being heavier than nonpregnant (dry) ewes in winter (by 1.7-4.2 kg). Pregnancy had no effect on fat depth or intake in autumn or winter. Lactating ewes were leaner (by 1.0-1.7 mm), had lower liveweights (by 6.4-8.6 kg), and had substantially higher intakes [by 286-348 g digestible organic matter intake (DOMI)/day] than non-lactating ewes. From summer to winter, ewes that had previously reared a lamb, or lambs, to weaning weighed less, were leaner, and had higher intakes than ewes that were previously dry. Pregnant ewes grew significantly less clean wool and grew it less efficiently (g wool/kg DOMI) in autumn (7-9% less) and winter (11-18% less) than non-pregnant ewes. Similarly, lactating ewes grew less wool (by 23-30%) less efficiently than ewes not suckling, the effect being greater in ewes with multiple lambs. Post-weaning, however, ewes that had reared a lamb to weaning grew significantly more wool (by 6-15%) up to 4 months post-weaning, although efficiency of wool growth was still impaired. The effects of reproductive status on the fibre diameter of wool reflected those for wool growth. Effects of reproduction on productivity are long term and recovery may not be achieved before the next reproductive cycle.

Effects of reproductive state on molt in the Japanese quail

AbstractMolt is induced in quail when they are transferred from photostimulatory long daylengths of 18L, with a fully active reproductive system, to short daylengths of 8L, when the reproductive system regresses. Gonadal steroids, but not gonadotrophins, inhibit molt in male and female Japanese quail. Molt can be induced in long‐term photostimulated (18L) quail by withdrawing gonadal steroids 1) by transferring quail to 8L, 2) by castrating males and maintaining them on a photoperiodic regime of 18L, or 3) by treating females or males with the antiestrogen, tamoxifen. In contrast, treatment of male quail with the antiandrogen, flutamide, does not induce molt even though androgen secretion is inhibited and androgen‐dependent tissues regress. Neither the exact mode of action nor the metabolite of gonadal steroids which inhibits molt is known, although estradiol is capable of inhibiting molt in females and to a lesser extent in males. Plasma levels of thyroxine are consistently elevated during molt. © 1993 Wiley‐Liss, Inc.

Effects of multiparity on age-related changes in female wistar rats.

Effects of reproductive status on the health of aged and young multiparous female rats were pathologically, hematologically, and blood biochemically investigated. Aged females were repeatedly mated and sacrificed at 2 years of age. Young females which were pregnant from one to three times were sacrificed at weaning, and compared with nulliparous ones of the same age. Tissue calcification in the renal and cardiovascular systems was characteristically observed in the aged multiparous females, but not in the young ones. Although serum calcium level of the aged multiparous females did not change, that of the young ones revealed a consistent decrease. There were no differences of incidences in age-related changes including neoplastic and non-neoplastic changes between the multiparous and the nulliparous aged females. We concluded that multiparity induced the tissue calcification of the renal and cardiovascular systems in aged females. In addition, our result suggested that multiparity had no effect on the occurrence of age-related changes.

Effect of reproductive status changes on family functioning and well-being of mothers and daughters.

Associations among family relations, mother reproductive status, daughter reproductive timing, and well-being were examined in 144 mothers and their adolescent daughters. First, effects of mother reproductive status and daughter reproductive timing on reports of family functioning were explored. Mothers of early maturing daughters perceived less family conflict than did those with on-time or late daughters. Second, the correlates of mother and daughter well-being were examined. Maternal perceptions of family cohesion were associated negatively with maternal depressive affect and positively with maternal body image. Maternal dieting behavior and bulimic symptoms were higher in postmenstrual mothers. For daughters, maternal perceptions of family cohesion were associated negatively with dieting and bulimic symptoms, and positively with body image. The interaction between mother menstrual status and daughter age at first menarche also influenced daughter dieting. Findings are discussed in terms of their implications for mother-daughter interaction during the adolescent years.

Plasma Sex Steroid-Binding Protein in Mature Heifers: Effects of Reproductive Status, Nutritional Level, and Porcine Growth Hormone, and Estradiol-17β Treatments1

In heifers, the specific 5 alpha-dihydrotestosterone (5 alpha-DHT) binding to sex steroid-binding protein (SBP) was 53 nM in midluteal phase and was 20% lower (p less than 0.05) in early luteal phase. In ovariectomized heifers on a high (H) or a low (L) energy diet, SBP bound testosterone with high specificity and estradiol-17 beta (E2) with a lower specificity; the affinity constant with 5 alpha-DHT was similar in the two groups independent of diet (Ka = 1.0 and 1.3 x 10(9) x M-1 for H and L heifers, respectively). Electrophoretic mobility of SBP was not affected by undernutrition. The specific 5 alpha-DHT binding to SBP in anestrous heifers compared to heifers in early luteal phase was 17% lower 18 days after cessation of ovarian activity (p less than 0.05) and 35% lower after 78 days of anestrus (p less than 0.001). Specific 5 alpha-DHT binding to SBP was 33% lower (p less than 0.001) in L heifers than in H heifers (40 nM). Porcine growth hormone (pGH) and E2 injections increased specific 5 alpha-DHT binding to SBP in both H and L heifers, but the effect depended on diet. Simultaneous injections of pGH and E2 increased specific binding in H heifers (p less than 0.02), whereas it had no effect in L heifers. We conclude that SBP binding capacity varies with ovarian activity in heifers and that nutritional status is one factor of regulation of SBP binding capacity because it affects binding and modifies the SBP response to stimulating factors such as pGH and E2.

The Effect of Reproductive State, Temperature, and Salinity on DNA and RNA Levels and Activities of Metabolic Enzymes of the Pyloric Ceca in the Sea Star Luidia clathrata (Say)

During the annual reproductive cycle, the pyloric ceca change in size and synthetic capacity. Changes in the amount of DNA indicated that seasonal changes in the size of the pyloric ceca resulted mainly from changes in the number of cells. The highest concentrations of RNA and the highest RNA:DNA ratios occurred during gametogenesis in the winter; lowest levels and ratios occurred in the summer or during environmental stress. Maximal activities of glucose-6-phosphate dehydrogenase (G-6PDH), 6-phosphogluconate dehydrogenase (6-PGDH), glycerolphosphate dehydrogenase (GPDH), glyceraldehyde-3-phosphate dehydrogenase (G-3-PDH), and pyruvate kinase (PK) occurred during gametogenesis. Exposure of Luidia clathrata to diferent temperatures in the laboratory did not affect the level of activities of G-6PDH, 6-PGDH, GPDH, and PK when measured at a constant temperature or concentrations of nucleic acids in the pyloric ceca. Activities of 6-PGDH, GPDH, and PK decreased, the concentration of DNA increased, and the concentration of RNA decreased in individuals exposed to low salinity. This resulted from decreased food intake and an apparent increase in the metabolic cost of cell-volume regulation. The significant efects of combinations of environmental factors indicate their importance when cellular responses during the reproductive cycle of L. clathrata are interpreted.

Effect of reproductive status, body condition and age of Bos indicus cross cows early in a drought on survival and subsequent reproductive performance

A herd of 802 Brahman cross cows, managed under extensive conditions (7000 ha paddock with twice-yearly handling) in a dry tropical environment, was studied during the severe drought of 1982-83. Twenty-one per cent of the cows died. Cows more advanced in pregnancy and those in poorer condition in the early stages of the drought had lower (P<0.05) survival probabilities. Cows aged over 7 years also generally had a reduced (P<0.05) probability of survival. Calf loss between confirmed pregnancy early in the drought and weaning after the following wet season was 31%. Calf loss from surviving cows was not higher than is usual in non-drought years. All deaths of lactating cows were associated with calf deaths. The practical use of these results in cost-efficient management for survival of cows in drought was then evaluated in a second study in which 293 cows were drafted into high- and low-supplement-requirement (HSR and LSR) groups in the early stages of the 1987 drought. Survival feeding in the HSR group commenced about 6 weeks earlier than would have been necessary in the LSR group. In both studies, reproductive status in the early drought period was a significant determinant of both body condition and conception rates early in the following year. Cows more advanced in pregnancy early in the drought were in poorer condition after the following wet season (P<0.05), but remained further advanced in pregnancy (P<0.05). Both body condition in the early part of the drought and age had minimal effects on performance in the following wet season, although younger cows tended to be lighter and have the lowest conception rates. Cows in better condition after the wet season had higher (P<0.05) pregnancy rates.

Effect of reproductive state and body size on food consumption in captive Galago senegalensis braccatus

AbstractMeasurements of food consumption for different types of foods were made for seven Galago senegalensis braccatus. Differences because of reproductive state in females and body size were found. Lactating females consumed more food in total and had greater energy and protein intake than they did during other reproductive states. Near‐term pregnant females consumed less food, energy, and protein than they did during other reproductive states. Body size affected food intake, with smaller animals ingesting more per unit metabolic weight than larger subjects.

Individual Contributions To Cooperative Behaviour in the Acorn Woodpecker: Effects of Reproductive Status, Sex, and Group Size

AbstractAcorn woodpeckers (Melanerpes formicivorus) are communal breeders that live in permanently territorial family groups of 2-15 individuals. All group members participate in several forms of cooperative behaviour, which we define as the investment of resources in a common interest shared by other group members (CHASE, 1980). Acorn woodpecker group interests include the caching of acorns in a specialized storage tree (the granary), maintenance of the granary, and defence of the granary against intra- and interspecific intruders. Because of a strong positive relationship between the availability of stored acorns and group reproductive success, investments in acorn storage, granary maintenance, and granary defence have a direct positive effect on the individual fitness of breeders. Non-breeding helpers, however, do not realize a direct reproductive reward, and therefore profit less directly from investment in these forms of cooperative behaviour. Thus, we predicted that breeders should invest more heavily in cooperative behaviour than should helpers. The prediction was upheld: for nearly every form of cooperative behaviour examined, breeders contribute significantly more than do helpers. On the other hand, while established breeders only rarely intrude on neighbouring territories, nonreproductive helpers frequently do so. These dispersal "forays" constitute attempts by helpers to locate ecologically restricted breeding vacancies. The effect that group size has on individual contributions to cooperative behaviour is unclear. Individual rates of acorn storage decrease significantly with increasing group size, but granary attendance and granary maintenance do not. Male and female acorn woodpeckers do not differ in their contributions to acorn storage, granary maintenance, or interspecific defence. Females, however, play a significantly greater role in intraspecific defence because of a female-biased intruder sex ratio and sex-specific defensive behaviour.

Effect of reproductive status on twinning and on side of ovulation and embryo attachment in mares

Brood-farm records were used to test several hypotheses concerning twinning and inequalities in the side of ovulation and embryo attachment. Ovulation occurred more frequently (P<0.05) from the left ovary (61% versus 39%) in maiden mares, but with equal frequency from either ovary in lactating and barren mares. The embryo attached more often (P<0.05) to the left horn in lactating mares (60%) and to the right horn in barren (59%) and maiden (67%) mares. Double ovulations and twin embryos were diagnosed more frequently (P<0.05) in barren mares (11% and 6%, respectively) than in lactating mares (5% and 1%). Pregnancy rates for double ovulations were affected (P<0.01) by the length of the interval between the two ovulations (0 days, 83%; 2 days, 87%; 4 days, 67%; 6 days, 54%; 8 days or more, 38%). Pregnancy rates were higher (P<0.01) for double ovulations 0 or 2 days apart (84%) than for single ovulations (54%). Twins were diagnosed more frequently (P<0.05) when double ovulations were two or more days apart ( 9 32 ) than when the ovulations were synchronous ( 0 19 ). These results support the conclusion that an embryo-reduction mechanism exists in mares for the elimination of excess embryos and indicate that the mechanism loses its effectiveness when the embryos originate from asynchronous ovulations.

Night roosting and the nocturnal time budget of the little brown bat, Myotis lucifugus: Effects of reproductive status, prey density, and environmental conditions.

The insectivorous bat Myotis lucifugus typically apportions the night into two foraging periods separated by an interval of night roosting. During this interval, many bats occupy roosts that are used exclusively at night and are spatially separate from maternity roosts. The proportion of the night which bats spend roosting, and thus the proportion spent foraging, vary both daily and seasonally in relation to the reproductive condition of the bats, prey density, and ambient temperature. A single, continuous night roosting period is observed during pregnancy. During lactation, females return to maternity roosts between foraging bouts, and night roosts are used only briefly and sporadically. Maximum use of night roosts occurs in late summer after young become volant. Superimposed upon these seasonal trends is day-to-day variation in the bats' nightly time budget. Long night roosting periods and short foraging periods are associated with cool nights and low prey density. This behavioral response may minimize energetic losses during periods of food scarcity.

Effect of reproductive state on circadian periodicity in the rat

The circadian activity rhythms of adult female rats maintained under a light-dark cycle of 14 hr light, 10 hr dark (LD 14:10) or constant dim illumination (dim LL) were recorded during their 4 or 5 day estrous activity cycles and when they were pseudopregnant. In LD 14:10 both the phase angle difference (ψ), which defines the temporal relationship between the onsets of activity and darkness, and the period (τ) of locomotor activity differed significantly among the days of the 4 and 5 day estrous cycle. Activity-time (α) varied reliably only over the days of the 5 day estrous cycle. The period of the free-running activity rhythm in dim LL also differed significantly among the days of the estrous cycle. In both LD and dim LL the most positive ψ, shortest τ and longest α were observed on the day of estrus. Pseudopregnancy diminished the amplitude and altered the daily pattern of the estrous activity rhythm. We conclude that the periodicity of circadian activity systematically varies as a function of the stage of the estrous cycle and in a manner that cannot be solely explained by corresponding alterations in endogenous estrogen.

Aggression in the female golden hamster: Effects of reproductive state and social isolation

To gain information on possible hormonal correlates, the aggressive behavior of intact female hamsters towards males was observed at various times during the estrous cycle, pseudopregnancy, pregnancy, and lactation. For methodological information, estrous cycle females also were tested after varying periods of social isolation. It was found that pregnant and especially lactating hamsters were more aggressive than pseudopregnant or estrous cycling females. Comparisons of days within each reproductive condition showed that aggression tended to be higher on certain days: the day preceding behavioral estrus of the estrous cycle, Day 10 of pregnancy, and the first 5 days of lactation. Except for pseudopregnancy, sexual behavior unaccompanied by aggression occurred at some time during all reproductive conditions, and both sexual behavior and aggression were found to occur together on Day 10 of pregnancy and Day 1 of lactation. The changes in aggressive behavior associated with reproductive states were attributed to increased male interest, inhibition by ovarian hormones, and facilitation by prolactin. Increasing periods of social isolation also were found to be associated with increased aggression. It was suggested that this effect, too. might have been due to increased prolactin levels.

Effects of pregnancy and lactation on the activities of some gluconeogenic and urea-cycle enzymes in sheep liver

SUMMARYThe effect of reproductive state on the activity in sheep liver of the gluconeogenic enzymes glucose-6-phosphatase and fructose-1,6-diphosphatase, and of the urea cycle enzymes arginase and the arginine synthetase system, was investigated. The sheep were Blackface ewes that were killed during pregnancy, lactation and after the lambs were weaned, together with non-breeding controls.The total activities in the liver of glucose-6-phosphatase, and of arginase, fell during pregnancy and rose during lactation in proportion to liver hypertrophy, reaching maximum values late in lactation.In breeding ewes total hepatic fructose-l,6-diphosphatase activity differed little from that in the controls except in the period 14 days before to 13 days after parturition, during which the activity was 10 times higher than at other times. The arginine synthetase system declined in activity during late pregnancy. There were 2 peaks in activity after parturition, one at 30 dayspost partumand one at 30 days after the lambs were weaned. The peaks possibly were associated with periods of resorption of maternal proteins.