Periods Of Nutritional Stress Research Articles

Effects of starvation on oxygen consumption, ammonia excretion and biochemical composition of the hepatopancreas on adult males of the False Southern King crab Paralomis granulosa (Crustacea, Decapoda)

Adults of the False Southern King crab, Paralomis granulosa, were starved between 0 and 12 days to evaluate the impact of fasting on the oxygen consumption, nitrogen excretion, O/N ratio and changes on biochemical composition of the hepatopancreas. During the experiment, no mortalities were recorded; physiological changes were detected after 6 days of fasting with an increase of nitrogen excretion ( p<0.05). After 9 days of starvation, the crabs showed a maximum decrease in the lipid content (4.3±1.2%, p<0.05), accompanied by an increase in oxygen consumption (53.1±10.9 μg O 2 h −1 g −1). The lowest O/N ratio was detected after 6 days (6.4±4.8) and the highest after 12 days of fasting (38.1±20.4), indicating that initially crabs utilized proteins as source of energy , followed by lipids. Moreover, after 12 days, there was a significant increase in the hepatosomatic index (HI) and total lipid content (9.7±1.0%, p<0.05), which could be associated with the re-absorption of other tissues to the hepatopancreas. Our results provide new information on this species that shows a different pattern of adaptation for each period of starvation and a good correlation between physiological and biochemical parameters. The ability to withstand and recover from periods of nutritional stress is an important adaptation for survival of any organism that must sporadically endure periods of limited food supply.

Variations in the birth sex ratio and neonatal mortality in a natural herd of horses

Variations in birth sex ratios and sex differences in juvenile mortality occur in a number of mammalian species, and in many cases have been linked to resource availability. Most of these biases in offspring sex ratios concern polygynous species with pronounced sexual dimorphism, and where females only are philopatric. Data on species with unusual life-history strategies, such as slight sexual dimorphism or dispersal by both sexes, are of particular interest. In this study of a natural herd of horses (Equus caballus) which experienced an eruptive cycle, and therefore a period of nutritional stress, male offspring had higher neonatal mortality rates in nutritionally poor years than in good ones, whereas “year quality” had no effect on the mortality of female offspring; year quality could therefore be used by mares as predictor of sex-specific offspring survival. We show that the environmental conditions that predicted lower survival of males were negatively related to their production: the birth sex ratio the following year was female-biased; and mares were less likely to produce a son when they had produced a son the preceding year. There was no significant effect of mother's parity, age or rank, or the timing of conception or birth on offspring sex ratios. The mechanism leading to biases in the birth sex ratio could have been the loss of male embryos by mares that did not foal. As there was no evidence for selective abortion of male foetuses in females that did foal the next year, it is not necessary to invoke maternal adjustment, though this remains a possibility. Finally, there was a suggestion that male offspring were more costly to raise than females, since mothers that reared a son in poor years tended to experience an increase in the interbirth interval between their two subsequent offspring.

The work patterns of lactating women in Madura

Little is known about the work patterns of mildly malnourished lactating women: are they modified to accomodate the demands of lactation? What factors influence their pattern of work during this period of nutritional stress? These questions were addressed using quantitative and qualitative data collected from 36 randomly selected women living in a poor community in Madura, Indonesia. Work patterns of the lactating women and their family members were documented for the first 12 months post-partum. Changes in work activity were analysed within four time periods corresponding to Madurese views on development during infancy: the vulnerable neonatal (birth-40 days), early (6–12wk) and mid (13–31 wk) stages and the independent late (32–54 wk) stage. Quantitative data suggest that women did adjust work patterns to accomodate the demands of lactation and that these adjustments went beyond the neonatal stage. Mothers curtailed their participation in high- and low-energy income-generating activities, modified their conditions of work to promote maternal-infant proximity and conserved energy while performing specific activities. These patterns were most common through the mid infancy stage. Data are presented that describe how cultural values supporting maternal-infant proximity, intra- and inter-familial work exchanges, season and resources played a role in the type of accommodations mothers were able to make to breast-feed. These data suggest that even in relatively poor environments alterations in work patterns that may be favourable to lactation are possible, particularly when cultural concepts of infancy support such a trade-off.

Regulation of peptide antibiotic production in Bacillus

In Bacillus species, starvation leads to the activation of a number of processes that affect the ability to survive during periods of nutritional stress. Activities that are induced include the development of genetic competence, sporulation, the synthesis of degradative enzymes, motility, and antibiotic production. The genes that function in these processes are activated during the transition from exponential to stationary phase and are controlled by mechanisms that operate primarily at the level of transcription initiation. One class of genes functions in the synthesis of special metabolites such as the peptide antibiotics tyrocidine and gramicidin S as well as the cyclic lipopeptide surfactin. These genes include the grs and tyc operons in Bacillus brevis, which encode gramicidin S synthetase and tyrocidine synthetase, respectively, and the srfA operon of Bacillus subtilis which encodes the enzymes of the surfactin synthetase complex. Peptide antibiotic biosynthesis genes are regulated by factors as diverse as the early sporulation gene product Spo0A, the transition-state regulator AbrB, and gene products (ComA, ComP, and ComQ) required for the initiation of the competence developmental pathway.

Effect of diet on steroid levels and reproduction in the starfish, Sclerasterias mollis

1. 1. The effect of diet on gonad and pyloric caeca condition and level of estrone and progesterone in gonads and pyloric caeca of the starfish Sclerasterias mollis was investigated. 2. 2. The gonad index, size of oocytes and pyloric caeca index were significantly higher in fed than in starved starfish. Protein levels also tended to be greater in the organs of fed than starved starfish. 3. 3. In both gonads and pyloric caeca, steroid levels of both sexes of starved starfish tended to be significantly higher than fed animals. 4. 4. Estrone levels were significantly higher in ovaries than testes of both starved and fed starfish. 5. 5. Progesterone levels were higher in testes than ovaries. 6. 6. Progesterone or their precursors appear to be transferred from the pyloric caeca to the gonads. 7. 7. There appear to be double mechanisms of both autolysis and liberation of components from cells of starfish during periods of nutritional stress.

Reproductive Responses to Nutritional Stress in Adult Female Collared Peccaries

The influence of nutrition on adult female collared peccary (Tayassu tajacu) breeding activity during the peak breeding season in Texas was studied under controlled conditions. Thirteen captive adults were fed either a high quality (15.2% crude protein and 3,300 kcal digestible energy/kg) or low quality (6.3% crude protein and 1,921 kcal digestible energy/kg) diet beginning 25 October 1983. The low quality diet simulated the energy and protein intake of an adult female during drought range conditions. During the peak breeding season (Jan-Feb) in 1985, a daily breeding program was implemented to monitor estrous behavior and fertility. All females were sacrificed after approximately 15 weeks. Three of 6 receiving the low quality diet showed no behavioral signs of estrus, whereas all females fed the high quality diet were bred. Duration of estrus averaged 1.3 and 3.5 days for cycling females on low and high quality diets, respectively. Only 1 of the 3 cycling females on the low quality diet became pregnant, whereas 6 out of 7 cycling females on the high quality diet became pregnant. Ovarian examination revealed <50% of the females receiving the low quality diet for 10 weeks entered the peak breeding season in an anestrous condition. This study suggests that prior nutritional stress among wild females will greatly influence the incidence of pregnancy and, hence, recruitment of young into the herd. J. WILDL. MANAGE. 50(2):295-300 Although the adult female collared peccary is a polyestrous breeder (Sowls 1966), the majority of breeding occurs during DecemberMarch in the southwestern United States. Field studies have shown substantial decreases in herd recruitment during periods of below average rainfall (Low 1970, Bissonette 1982, Sowls and Maurer 1985), presumably as a result of decreased quality or quantity of nutritionally adequate foods. Currently it is not known where in the peccary reproductive cycle potential recruits are lost or which physiological states are ost affected by nutritional stress mediated by rainfall. Recent observations support the hypothesis that nursling postnatal survival and ovarian activity are susceptible to periods of nutritional stress. Bissonette (1982) indicated postnatal mortality of nurslings contributed to low recruitment in southwestern Texas peccary populations. Few conceptions occur during summer, and seasonal delays in onset of peak breeding have been observed when range con'Present address: Department of Zoology, Oklahoma State University, Stillwater, OK 74078. This content downloaded from 157.55.39.102 on Mon, 03 Oct 2016 06:14:36 UTC All use subject to http://about.jstor.org/terms 296 PECCARY REPRODUCTIVE RESPONSES * Lochmiller et al. J. Wildl. Manage. 50(2):1986 Table 1. Ingredient and chemical composition of pelleted, experimental diets fed ad libitum to pregnant collared peccaries in southern Texas, October 1983-February 1984.

Condition and related mortality of nyala Tragelaphus angasi in Zululand, South Africa

The kidney fat index (KFI) was used to examine the condition of nyala over a 27‐m‐onth period. From a sample in which both marrow fat and KFI were examined, it was noted that, as has been found in other bovid, kidney fat was mobilized before marrow fat. Seasonal changes in condition were observed and correlated with the rainfall in the previous month. Following periods of less than 50 mm of rain, the larger adult males were in significantly poorer condition than other animals.The sexual difference in condition is attributed to the differences in body size, where males of asymptotic body mass required 62% more kcal/day than asymptotic mass females. When die‐offs occurred during periods of nutritional stress, significantly more old adults died than would be expected. Further, significantly more males died than females.

Periods of Nutritional Stress in the Annual Cycles of Endotherms: Fact or Fiction?

An animal's nutritional status depends on (1) nutrient accessibility, (2) nutrient demand, and (3) physiological, metabolic, morphological, and behavioral compensations that avert or minimize discrepancies, if any, between the first two. The main thesis of this essay is that the diversity and potency of such compensatory mechanisms have often been underrated, and hence the frequency and intensity of nutritional stress in free-living animals have often been exaggerated. This theme is explored in conjunction with an inventory of the modes of compensation for actual or potential dietary deficiencies.

Time-Budgets of Camargue Horses Iii. Environmental Influences

1. Time-budgets of female, male and yearling horses were calculated for 34 weeks over two years. There was little variation in the time spent in different activities during autumn and winter (Aug.-Mar.). 2. The horses spent more time lying (sleeping) in spring, when on a high protein diet. In summer they spent more time standing alert and walking, less feeding, probably because of the attacks by biting Diptera. 3. Within autumn and winter standing alert decreased when mosquitoes were abundant and standing resting, usually in shelter, increased on days with low maximum temperatures and during rain. Feeding time was unaffected by these variables. 4. The breeding mares increased their feeding times during periods of nutritional stress (end of winter, peak lactation) but only by 6-8%. 5. The time-budgets of these horses showed less variation than has been found in some ruminants. It is argued that for most of the year their feeding time is close to the maximum value allowed by the need to perform other activities, principally resting and moving.

The use of nutritional therapy

Nutritional support for children with cancer is predicated on the belief that optimal nutrition promotes tolerance of anti-neoplastic therapy and preserves immunologic responsiveness. The use of nutritional support is based on the assumption that there is effective therapy for the primary disease and that there will be a predictable period of nutritional stress. The most common nutritional problem is posed by the failure of sick children willingly to eat enough to maintain nutritional homeostasis. Supplementation of oral intake with a nutritional formula given by a small-bore nasogastric tube is simple, effective, and economical. If the sum of oral and tolerated nasogastric tube feedings is less than that required for optimal nutrition, unmet needs may be satisfied by nutrients given into a peripheral vein. Total parenteral nutrition, given by central vein, is reserved for situations in which the combination of enteral and peripheral venous alimentation is inadequate.

Body Composition and Reserves of Energy of Microtus pinetorum from Southwest Virginia

Body composition of Microtus pinetorum was explored in relation to month of capture, sex, age and reproductive status. There were significant bimonthly differences in concentrations of body water, ash and caloric value of live weight biomass (LWB) and dry weight biomass (DWB). There was no difference between males and females for any body component. Juveniles had higher mean annual concentrations of fat and water, and higher mean annual caloric values of DWB and LWB than adults. Pregnant and lactating females had lower mean annual concentrations of fat and caloric values, of LWB and DWB than nonbred adult females. Reproduction and growth during periods of nutritional stress resulted in significant decreases in concentrations of body fat and reserves of energy. INTRODUCTION Determinations of seasonal changes in body composition and reserves of energy are fundamental to understanding the transfer of energy through a small mammal population. Previous studies have shown body composition of rodents differs among species, seasons, habitats, sexes, ages, reproductive conditions, geographic distributions and environmental conditions (Gorecki, 1965; Hayward, 1965; Sawicka-Kapusta, 1968; Evans, 1973; Fleharty et al., 1973; Schreiber and Johnson, 1975; Bergeron, 1976; Kolodziej-Banach, 1976; Jagosz et al., 1979; Millar, 1981). Only Cengel et al. (1978) examined body composition (reserves of fat) in relation to season, habitat and sex in Microtus pinetorum. Body fat has been suggested as a physiological indicator of changes in food quantity and quality of small rodents (Judd et al., 1978; Merson, 1979; Merson and Kirkpatrick, 1981). Cengel et al. (1978) found a significant relationship between the nutritional quality in the habitat and the amount of pine vole body fat. Our study quantified further the body composition and reserves of energy of wild pine voles. The objective was to determine the sensitivity of body composition and reserves of energy to changes in season, reproductive status, age and sex, and to assess the relationship between body composition and the level of nutritional demand for energy. METHODS Adult and juvenile Microtus pinetorum were snap-trapped with apples as bait from May 1978 to March 1979 in two rural apple orchards located in Botetourt Co., in SW Virginia. Voles > 20 g in body mass were considered adults, those < 20 g, juveniles (Paul, 1970). Trapped voles were weighed, split midventrally, and the alimentary tract and the liver removed. Mesentery fat adhering to the alimentary tract was trimmed away and replaced in the body cavity. The weighed carcasses were frozen and then lyophilized for 48 hr. The difference between mass at the time of trapping and mass after lyophilization was concentration of water (expressed as percent live body mass). Each dry carcass was ground to a fine mix. Approximately three-fourths of the homogenate was analyzed for fat (expressed as percent dry body mass) by 16 hr of ether 1 Present address: Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station 77843. 2 Present address: U.S. Forest Service, 3825 E. Mulberry, Room 259, Fort Collins, Colo. 80524.