Energetics of reproduction in female and male greater snow geese

Arctic-nesting geese are classified as capital breeders (i.e., birds that rely largely on endogenous reserves to meet the high nutrient requirement of clutch formation) as opposed to income breeders (those that rely directly on ingested food). However, some evidence has suggested that energy reserves of greater snow geese (Chen caerulescens atlantica) are not sufficient to meet these costs. We tested whether greater snow geese were capital breeders and examined the consequences on their reproductive strategy. We collected 48 females and 47 males from arrival at the breeding colony on Bylot Island (NWT) to the postlaying stage, and determined fat and protein content in somatic and reproductive tissues. Rapid follicular growth was initiated only after arrival on the breeding ground. Somatic fat of females tended to increase during the prelaying and laying stages at the same time that most of the fat was deposited in developing follicles. Decrease in somatic fat in postlaying females was mostly related to its use for meeting metabolic requirements during early incubation. Hence, almost all fat invested in the clutch came from food intake, not endogenous reserves. Somatic protein was maintained during prelaying but decreased during laying, suggesting that some protein reserves were deposited in the eggs. There was no relationship between somatic fat and the number of developing follicles (incubating females excluded) but a relationship was found with somatic protein. Clutch size was not related to body size. In males, somatic fat, which was similar to females at arrival, was almost completely depleted by the postlaying stage. Male somatic protein remained stable. Male somatic reserves were not related to the somatic reserves, clutch size or nutrient investment in reproduction of their mate. We conclude that, in female greater snow geese, little fat reserves (if any) were used for egg formation though some protein reserves were used, whereas males relied heavily on their fat reserves during the same period. This is probably a consequence of the long and costly migration between the last staging area and the breeding grounds.     

Validated age and growth of the leopard shark,Triakis semifasciata,with comments on reproduction

Synopsis The age, growth, and sexual maturation of the leopard shark, Triakis semifasciata, from central California were studied. Growth band counts in vertebral centra of 162 leopard sharks produced von Bertalanffy growth curves with L, K. and t_o parameters of 1536 mm. 0.082, and -2.31, respectively, for both sexes combined. The L₈ value for females (1602 mm TL) was slightly but insignificantly higher than for males (1499 mm TL), but the K and t_o values were almost identical. Seasonal changes in size modes of young-of-the-year leopard sharks, centrum edge characteristics, and growth and tetracycline mark-recapture from the field were used to validate annual deposition of vertebral centrum band pairs. Sexual maturity was evaluated by the gonads and presence of sperm and eggs; males mature at 7 yr and at about 63% of asymptotic length, and females mature at 10 yr, and at about 72% of asymptotic length. This slow growth, late maturity, and relatively low fecundity may increase their susceptibility to over-exploitation.     

Effect of constant-release implants of melatonin on seasonal cycles in reproduction, prolactin secretion and moulting in rams

Seasonal cycles in the size of the testes, blood plasma concentration of testosterone, FSH and prolactin, intensity of the sexual skin flush, timing of rutting behaviour and moulting of the body coat were recorded in Soay rams after s.c. implantation of melatonin contained in a Silastic envelope which increased the circulating blood levels of melatonin to 200-600 pg/ml for many months. Two groups of 8 adult rams were held under alternating periods of short days (8L:16D) and long days (16L:8D) to drive the seasonal cycles and the treatments with melatonin were initiated during the long or short days, and one group of 8 ram lambs was kept out of doors and given implants during the long days of summer (4 melatonin-implanted and 4 control (empty implants) rams per group). The treatments demonstrated that melatonin implants during exposure to long days resulted in a rapid 'switch on' of reproductive redevelopment similar to that produced by exposure to short days melatonin implants prevented the rams from showing the normal responses to changes in the prevailing photoperiod rendering them nonphotoperiodic; and long-term cyclic changes in testicular activity, prolactin secretion and other characteristics occurred in the melatonin-implanted rams; the pattern was similar to that previously observed in rams exposed to prolonged periods of short days. The overall results are consistent with the view that melatonin is the physiological hormone that relays the effects of changing photoperiod on reproduction and other seasonal features, and that continuous exogenous melatonin from an implant interferes with the normal 'signal' and produces an over-riding short-day response.     

Carcass composition and meat quality of indigenous Yanan pigs of China

The Yanan (YN) pig is a traditional Chinese indigenous breed that is raised in southwest China in the Sichuan Province, but there is little data on the germplasm characteristics of this breed. To evaluate carcass characteristics and meat quality of the YN pig, we compared carcass and meat quality of YN pigs and Landrace × Yanan (CY) hybrid pigs; 30 YN pigs and 30 CY pigs weighing 20 ± 2 kg were reared and slaughtered at the normal slaughter weight (100-120 kg). The carcasses were chilled and the left carcass side was dissected into bone, lean meat, fat, and skin; meat quality parameters were measured. Carcasses of YN pigs were lighter (88.85 vs 90.05 kg, P < 0.05) and shorter (71.88 vs 77.61 cm, P < 0.001); they contained less lean meat (41.60 vs 49.25%, P < 0.001), less ham and breech (25.93 vs 27.53%, P < 0.001) and less carcass bone (9.83 vs 10.53%, P < 0.01) than did carcasses of CY pigs. On the other hand, YN pigs had more carcass subcutaneous fat and skin (48.58 vs 40.23%, P < 0.001), thicker backfat (3.67 vs 3.43 cm, P < 0.001) and smaller loin muscle area (9.83 vs 26.91 cm(2), P < 0.001) compared with CY pigs. Among meat quality parameters, YN pigs had higher pH(1) (6.41 vs 6.17, P < 0.001), higher color score(u) (3.86 vs 3.36, P < 0.001) and lower Minolta L(u) values (40.89 vs 45.32, P < 0.01) than CY pigs. On the other hand, YN pigs had lower drip loss (1.31 vs 2.26%, P < 0.05) and lesser fiber area (2351.34 vs 3025.43 μm(2), P < 0.01) than CY pigs. Both breeds had high intramuscular fat (4.46% in YN and 4.45% in CY). No significant differences in other carcass traits and meat quality were found in the two populations. We conclude that YN pigs could be used in commercial pig production to provide good tasting and high-quality niche products.     

Alteration of salt marsh plant community composition by grazing snow geese

A notable omission from wetlands ecology has been the study of the influence of herbivores on vegetation. Reported here are the effects of grazing by snow geese Anser caerulescens altantica on the vegetation of salt marshes along the mid-Atlantic coast of the United States, Exclosures were used to compare total and species percent cover between grazed and ungrazed areas in three marshes (Salt Flats, South Pond, and Bodie Island) with differing vegetation communities from 1978 to 1980.
Spartina alterniflora was reduced by ⅔ in grazed versus ungrazed areas of Salt Flats, S. S. patens was reduced by ½ in grazed portions of South Pond but recovered when grazing ceased. In grazed portions of Bodie Island total plant cover was reduced by 16%. Scirpus robustus and S. patens reacted in opposite ways to grazing pressure with S. robustus increasing and S. patens decreasing, Elocharis was found only in grazed areas of Bodie Island. Echinochloa crusgali appeared in grazed portions of this marsh in 1978 but decreased in abundance during subsequent years. Scirpus americanus was unaffected by grazing, maintaining a nearly constant percent cover in grazed and ungrazed areas at Bodie Island.
Differences in responses to grazing are discussed in terms of each species' growth and reproductive strategies as tempered by the physical and biological environment within each marsh.     

Associations between body composition and helminths of lesser snow geese during winter and spring migration

Costs of parasitism are predicted to be higher with greater parasite intensities and higher inter-parasite competition (diversity). We tested whether greater helminth intensities and diversity were associated with poorer body composition (whole-body fat, protein, mineral and true body mass) in lesser snow geese, Chen caerulescens caerulescens. As part of a larger study on nutritional ecology, 828 wintering or migrating geese were shot between January and May 1983 in 27 different date-locations (samples) during their northward migration through mid-continental North America. A large proportion of overall variation in body composition and parasite communities was among samples, so we analyzed data within each of the 27 samples, controlling for structural body size (the first principal component of 10 body size measurements), sex and the age of geese. There was no compelling evidence that cestodes, trematodes or helminth diversity were associated with variation in body composition but nematodes had several negative associations with fat reserves. However, negative associations between fat reserves and nematodes occurred most often in geese collected between March and May when nematode prevalences and intensities were relatively low. This suggests several possibilities: that the most common nematodes (Heterakis dispar and Trichostrongylus tenuis) were more virulent at this time, that infected individuals had been chronically infected and suffered cumulative nutrient deficits that lasted until late in the spring migration, or that geese became more vulnerable to the effects of parasites at this time of year, possibly because they redirected resources away from immunity toward fat storage in preparation for reproduction.     

The role of farm dams in the ecology of spur-winged geese (<Emphasis Type="Italic">Plectropterus gambensis</Emphasis>) on the Highveld,South Africa

This paper describes the use of farm dams by spur-winged geese (Plectropterus gambensis) on the Highveld of South Africa. Applications for mining rights on coal seams located under wetlands have increased, which raises the question whether the loss of the waterfowl habitat can be mitigated. Since the spur-winged geese were observed on natural wetlands and man-made farm dams, these birds were selected to determine whether they are compatible with dams. A transect of 145 km was traversed weekly with a vehicle from January 2013 to December 2014, to count geese on farmland at Heidelberg, Vaal Dam, Grootvlei and Balfour. The purpose was to describe (1) habitat use of geese on farmland, (2) the limitations of farm dams as offset habitats and (3) habitat improvement. The geese preferred natural wetlands over farm dams but foraged on arable land rather than natural grassveld. Spur-winged geese rest on farm dams during the rainy season, although these dams are not used for breeding or flightless moult and therefore can only be regarded as partial offset for natural wetlands. Increasing the area of shallows at the inflow of larger dams in open landscapes with fringing vegetation may encourage breeding. However, it may take 5–10 years for fringe vegetation to become established and attractive for breeding, meaning that an offset habitat cannot be created over the short term.     

Effect of the composition of the growth medium on morphology and reproduction ofAzotobacter chroococcum

Summary The growth of threeAzotobacter chroococcum strains was investigated in a number of media. The cultures were incubated at 29°C. and studied by means of a Wild phase contrast microscope. The experiments have clearly demonstrated that the morphology and reproduction ofA. chroococcum are influenced greatly on the one hand by conditions of nutrition and on the other hand also by the properties of the strains. Although all strains used in this work were able to produce gonidia and regenerative rods, these were not found in all media. The formation of filamentous cells, and vegetative cells inside such cells, depended also on the medium and, in some cases, on the strain. Cysts could sometimes resist a temperature of 50°C. for 5.5 minutes, but not a single strain with cysts survived temperatures of 60°C. or higher. Spores could not be detected by the usual staining methods.     

Repeated grazing of a salt marsh grass by moulting greylag geese Anser anser– does sequential harvesting optimise biomass or protein gain?

The effects of simulated goose grazing on common saltmarsh-grass Puccinellia maritima plants were tested on a Danish salt marsh during the flightless moulting period of greylag geese Anser anser (3–21 June 1998). Plants in an area exclosed from the influence of grazing and the nutrient effects of goose faeces were subject to removal of youngest lamina at 3-, 6-, 9- and 18-day intervals during this period. Average biomass and protein accumulation between harvests was highest at defoliation intervals of 9 days or more. Field observations from two separate study areas demonstrated geese returned to regraze the Puccinellia sward after 6–8 days and oesophageal contents from feeding geese showed selection for lamina lengths consistent with the results of clipping every 6 days. Geese therefore regrazed Puccinellia patches at shorter intervals than expected were they to maximise their intake of biomass or protein at each visit. However, total cumulative lamina elongation, equivalent to the long term gain during the entire moult period, showed no significant difference between the three most intensive defoliation treatments, which were significantly greater than those of plants defoliated at 18 day intervals. Highest overall lamina protein levels were maintained at 6- and 9-day defoliation intervals. This suggests geese regrazed Puccinellia patches at a rate that maximised their number of harvests during the flightless period, but maintained highest protein levels and overall biomass in the sward. This suggests, in line with earlier studies, that moulting greylag geese combine dietary selection, reduced nitrogen excretion and regrazing patterns to meet protein demands during regrowth of flight feathers.     

Intraovular development and moulting of Toxocara pteropodis

Observations of Toxocara pteropodis eggs removed from an adult worm and embryonated in 0.05 M-sulphuric acid showed the first moult to occur on the sixth day followed by the second moult over days 8-11, as indicated by the finding of a transient, loose, double-layered sheath over the definitive cuticle. Infectivity to mice first developed on day 11, reached a maximum at 36 days and then waned over the next 6 months. Details of larval development are described and the significance of loose sheaths on larvae recovered from tissues is discussed.     

A preliminary analysis of the diet composition of overwintering Bean geese (Anser fabalis) and greater white-fronted geese (A. albifrons) in Korea using PCR on fecal samples

Bean geese (Anser fabalis) and Greater white-fronted geese (Anser albifrons) are the dominant wintering waterfowl in South Korea. Although they are commonly observed in estuaries and rice fields during the winter, the diet composition of the geese during the winter has rarely been studied. In this study, we provide the results from preliminary analyses on the diet of these two geese species overwintering in Daebu Island of South Korea. We used a total of 13 fecal samples from Bean geese (n?=?4) and Greater white-fronted geese (n?=?9), and performed a BLAST search for the sequences obtained from 87 clones (n?=?36 for Bean geese and n?=?51 for Greater white-fronted geese). The diet of Bean geese consisted of five families of plants: Caryophyllaceae (75.0%), Poaceae (13.9%), Asteraceae (5.5%), Polygonaceae (2.8%) and Cucurbitacea (2.8%). On the other hand, the diet of Greater white-fronted geese consisted of 6 families of plants: Poaceae (74.5%), Caryophyllaceae (9.8%), Solanacea (5.9%), Portulacaceae (3.9%), Lamiaceae (3.9%) and Brassicaceae (2.0%). We found that plants of the rice family (Poaceae) are important in the diet of wintering geese, especially for Greater white-fronted geese. This knowledge can be used to establish conservation strategies of the geese overwintering in South Korea.     

The influence of bacteria-dominated diets on Daphnia magna somatic growth, reproduction, and lipid composition

We explored how dietary bacteria affect the life history traits and biochemical composition of Daphnia magna, using three bacteria taxa with very different lipid composition. Our objectives were to (1) examine whether and how bacteria-dominated diets affect Daphnia survival, growth, and fecundity, (2) see whether bacteria-specific fatty acid (FA) biomarkers accrued in Daphnia lipids, and (3) explore the quantitative relationship between bacteria availability in Daphnia diets and the amounts of bacterial FA in their lipids. Daphnia were fed monospecific and mixed diets of heterotrophic (Micrococcus luteus) or methanotrophic bacteria (Methylomonas methanica and Methylosinus trichosporium) and two phytoplankton species (Cryptomonas ozolinii and Scenedesmus obliquus). Daphnia neonates fed pure bacteria diets died after 6-12?days and produced no viable offspring, whereas those fed pure phytoplankton diets had high survival, growth, and reproduction success. Daphnia fed a mixed diet with 80% M.?luteus and 20% of either phytoplankton had high somatic growth, but low reproduction. Conversely, Daphnia fed mixed diets including 80% of either methane-oxidizing bacteria and 20% Cryptomonas had high reproduction rates, but low somatic growth. All Daphnia fed mixed bacteria and phytoplankton diets had strong evidence of both bacteria- and phytoplankton-specific FA biomarkers in their lipids. FA mixing model calculations indicated that Daphnia that received 80% of their carbon from bacteria assimilated 46?±?25% of their FA from this source. A bacteria-phytoplankton gradient experiment showed a strong positive correlation between the proportions of the bacterial FA in the Daphnia and their diet, indicating that bacterial utilization can be traced in this keystone consumer using FA biomarkers.     

Effect of diet composition on feeding,digestion, and reproduction in Glossina morsitans

Quantitative estimates of food intake by adult female Glossina morsitans were made using ⁴⁵Ca in the diet. Rate of digestion was measured by estimating residual nitrogen in the gut contents at various intervals after feeding. Results show that the superiority of pig blood over cow blood as a diet for in vitro feeding of Glossina cannot be explained in terms of quantities ingested or in terms of digestion rate by the fly. Comparing blood from a number of mammalian hosts, only that of pig elicited production of optimal sized offspring and no correlation could be found between haemoglobin content or trypsin inhibition capacity and offspring size for any of the bloods tested. An exchange of protein fractions between pig and cow blood failed to demonstrate a specific component of pig blood which accounts for its nutritional superiority. Removal of serum, and suspension of washed pig erythrocytes in a saline solution resulted in production of very small offspring. However, the addition of physiological concentrations of soluble albumen to such a suspension produced an improvement in both fecundity and offspring size. Feeding on serum alone or upon serum containing added albumen in solution resulted in poor survival and fecundity was reduced to zero. Results emphasize the importance of both serum and erythrocyte components of blood in providing an optimal diet for Glossina.     

Effect of substance P on the reproduction of memory engrams and on the amino acid composition of brain structures in rats with experimental neurosis

Formation of experimental neurosis in rats was accompanied in 64% of animals by development of amnesia of conditioned reaction of passive avoidance. Disturbance of mnestic processes was manifested by a change in free amino acids pool including the acids with neurotransmitter properties (GABA, glutamate, glycine). An increase of GABA and glycine content was found in the frontal cortex and an increase of glutamate and GABA--in the hippocampus and striate body. Substance P (125 mkg/kg) administered intraperitoneally against the background of a developed neurosis, produced in 80% of cases an antiamnestic action, accompanied by a statistically significant decrease of GABA content in the frontal cortex, hippocampus and midbrain, and an increase of glutamate in the midbrain. The level of taurine decreased in the frontal cortex, hippocampus and striate body, and increased in the midbrain. Threonine content increased in the striate body and midbrain; there was an increase of taurine, serine and glycine in the midbrain and of glycine in the striate body.