Oestrus in the lactating red kangaroo.

1964 ◽  
Vol 12 (3) ◽  
pp. 315 ◽  
Author(s):  
AE Newsome
Keyword(s):  
Corpus Luteum ◽  
Reproductive Cycle ◽  
Environmental Conditions ◽  
Similar Case ◽  
Severe Drought ◽  
Reproductive Condition ◽  
Pregnant Females ◽  
Red Kangaroo ◽  
Central Australia ◽  
Poor Nutrition

The reproductive condition of 18 female red kangaroos, Megaleia rufa (Desmarest), collected in central Australia and found to be suckling sizeable pouch young (average age about 54 days), is described. They were either approaching, undergoing, or had just undergone oestrus. None had a mature corpus luteum of lactation in either ovary. No similar case was found in many hundreds of females suckling sizeable pouch young which had a mature corpus luteum of lactation in one of their ovaries. It is concluded that the presence of a functional corpus luteum of lactation or of pregnancy in the ovary may be the only inhibitor of ovulation in the mature Megaleia, provided that environmental conditions are suitable. Some kangaroos during severe drought miss the customary oestrus following birth of a young because the pregnant females do not undergo the reproductive changes necessary for it. Despite this disruption of the reproductive cycle the young are born and suckled normally, but the females cannot, therefore, have a corpus luteum of lactation. The 18 females described in this paper must have belonged to this class of animals during the drought, their condition having been brought on presumably by poor nutrition. The unusual features of reproduction in Megaleia are hard to reconcile with the assumptions that pregnancy in marsupials depends on the hormones of the normal oestrous cycle, and that reproduction in marsupials is controlled by the same kinds of hormones found in eutherian mammals; doubt is, therefore, thrown on the validity of these assumptions. Megaleia has a remarkable ability to care for its young during severe drought, and a method of overcoming the effects of the drought on its reproductive cycle when the drought breaks, with the result that the production of young is not impaired. Both these features must aid the chance of the species to survive in the arid parts of Australia.

Reproduction in natural populations of the red kangaroo, Megaleia rufa (Desmarest), in central Australia.

1965 ◽  
Vol 13 (5) ◽  
pp. 735 ◽  
Author(s):  
A. E. Newsome
Keyword(s):  
Drought Index ◽  
Natural Populations ◽  
Late Pregnancy ◽  
Arid Environment ◽  
Adaptive Significance ◽  
Severe Drought ◽  
Summer Drought ◽  
Red Kangaroo ◽  
Males And Females ◽  
Central Australia

Reproduction in the red kangaroo, Megaleia rufa (Desmarest), in the arid environment of central Australia is highly opportunistic, and depends on the weather through its control of the food supply for its success. This conclusion is based on the study of 460 males and 1610 females between the years 1958 and 1962. Males and females matured sexually at an average age of about 2.5 and 3 yr, respectively. Drought significantly retarded sexual maturity in females by 6.24� 1.26 months. All females bred when green herbage was abundant after good rains. However, when food was scarce during drought, many females entered anoestrus, the proportion doing so being a probit function of the severity of the drought (measured in units of "drought index" explained in the text). Half of them became anoestrous after 3-5 months of drought in summer. Drought on the more scantily grassed of the two areas studied (they were 15-20 miles apart) was 1.57 times more effective in inducing anoestrus than on the other. All pouch-young survived if good conditions held for about 8 months, but many died during drought, the proportion doing so being a probit function of the increase in severity of drought after they were born. Half of them perished after 1.5-2.5 months of drought in summer. Only 28.7% of all joeys born survived life in the pouch because of the prolonged dry weather. Pouch-young were significantly lighter, and joeys-at-heel were 13.5 � 1.9 days older during drought than at other times. The birth of twin joeys was associated with an abundance of food. During severe drought, many females showed signs of having produced in quick succession one or more joeys which did not live long. Many of these females were anoestrous and suckling a small joey. Since most if not all females which became anoestrous did so during late pregnancy without aborting and subsequently suckled their pouch-young, it is suggested that the adaptive significance of delayed implantation is to ensure that females which have lost a joey and which are about to become anoestrous produce one more joey each. These joeys will be born well into any drought and therefore will have to live for a shorter time than older joeys to survive the drought. The advantage to the species can be gauged from the fact that 50 out of 145 females with young surviving the drought were anoestrous. The ages of their joeys averaged 60.1 � 7.6 days.

scholarly journals Distribution of guppies Poecilia reticulata (Peters, 1860) and Phalloceros caudimaculatus (Hensel, 1868) along a polluted stretch of the Paraíba do Sul River, Brazil

2009 ◽  
Vol 69 (1) ◽  
pp. 41-48 ◽  
Author(s):  
FG. Araújo ◽  
MG. Peixoto ◽  
BCT. Pinto ◽  
TP. Teixeira
Keyword(s):  
Environmental Conditions ◽  
Poecilia Reticulata ◽  
Condition Factor ◽  
Spatial Separation ◽  
Fishing Effort ◽  
Seasonal Patterns ◽  
Industrial Complex ◽  
Pregnant Females ◽  
Significant Difference ◽  
Paraíba Do Sul River

Cyprinodontiformes fishes (guppies) are widely distributed in Neotropical regions and use deteriorated microhabitats in rivers where few species can occur. This study was carried out in a stretch of the Paraíba do Sul River in bracketing a large urban-industrial complex. The aim was to assess eventual effects that the industrial complex could have on distribution of two closely related fish species of guppies, Phalloceros caudimaculatus and Poecilia reticulata. The area was divided into three zones: Z1, 40 km upriver of the major urban-industrial complex of Volta Redonda; Z2, just down river of the complex; and Z3, 30 km down river of the complex. Six sites (two in each zone) were sampled monthly between November 1998 and October 1999, using a standardized fishing effort with cast net throws, trays lifts and seine hauls, covering different microhabitats, that is, riffles, pools and the proximity of the river's margins. Poecilia reticulata was widely distributed, peaking at Z2, the most polluted area, while P. caudimaculatus showed the highest abundance at Z3, being almost absent in Z1. Both species occurred in high numbers throughout the year but they were scarce between April and June. Females outnumbered males for both species in most size classes and at all sites. Juveniles were more abundant than adults, with non-pregnant females outnumbering pregnant ones. Condition factor was always higher in males than females but only males P. reticulata showed significant difference among the three zones, with the highest values at Z2. The higher number of females confirms the expectation that these species can use very polluted areas and that availability of food provided by organic loads allowed their distribution all over the area. Although these two species have shown indication of spatial separation in the study area, their similar seasonal patterns of occurrence suggest that they respond in a similar way to changes in environmental conditions.

Development and regression of the corpus luteum in grey seal (Halichoerus grypus) ovaries and its use in determining fertility rates

1984 ◽  
Vol 62 (6) ◽  
pp. 1095-1100 ◽  
Author(s):  
I. L. Boyd
Keyword(s):  
Corpus Luteum ◽  
Adult Female ◽  
Halichoerus Grypus ◽  
Embryonic Diapause ◽  
Grey Seal ◽  
Fertility Rates ◽  
Reproductive Condition ◽  
Plasma Progesterone ◽  
Blood Samples ◽  
Foetal Growth

Adult female grey seals were sampled at the Fame Islands at monthly intervals from November 1980 to October 1981. The distribution, size, and number of ovarian corpora were recorded in each case and blood samples were obtained for progesterone analysis. The concentration of plasma progesterone was about 6 ng/mL for most of gestation, including embryonic diapause, and rose to about 10 ng/mL during the final month. Progesterone declined sharply to less than 1 ng/mL at parturition. The size of the corpus luteum was constant throughout embryonic diapause, but after implantation it grew continuously until parturition. Following parturition, it regressed rapidly at first, forming a corpus albicans, and then more slowly, regression being arrested during the period of foetal growth of the following reproductive cycle. Most corpora albicantia had disappeared 1 year after their formation. Corpora albicantia may be useful indicators of reproductive history in grey seals, providing that allowance is made for the reproductive condition of females at the time of sampling and for several other possible errors which could arise. Retrospective calculation of reproductive statistics by more than 1 year using corpora albicantia is not valid for grey seals.

Seasonal Changes in Diet Preferences of Free-Ranging Red Kangaroos, Euros and Sheep in Western New South Wales.

1977 ◽  
Vol 4 (2) ◽  
pp. 127 ◽  
Author(s):  
BA Ellis ◽  
EM Russell ◽  
TJ Dawson ◽  
CJF Harrop
Keyword(s):  
Animal Species ◽  
New South ◽  
New South Wales ◽  
Stomach Contents ◽  
Ovis Aries ◽  
Severe Drought ◽  
Red Kangaroo ◽  
South Wales ◽  
Selective Eating ◽  
Free Ranging

Stomach contents of free-ranging animals were analysed botanically for low Atriplex shrubland in western New South Wales, Australia, during 1972-74 in good seasons producing abundant growth and diversity of vegetation. Red kangaroo (Megaleia rufa), euro (Macropus robustus) and sheep (Ovis aries) selected grass and forbs when those were readily available. In poorer pasture sheep selected mainly flat-leaved chenopods (saltbush) and kangaroos selected mainly grass with different amounts of flat- or round-leaved chenopods. Euros were the most selective, eating grass even when there was little grass present. Potential overlaps in diet between kangaroos and sheep were greatest in good pasture and least in the poorest conditions. The other groups of plants considered were non-chenopod shrubs and browse. Extent of overlap was not clear, because animals may have eaten different species within the groups of plants. The study period did not include any severe drought, in which overlap in diet and competition between animal species would have been most significant.

Reducing lamb mortality in hill sheep

1992 ◽  
Vol 15 ◽  
pp. 179-182
Author(s):  
A. Waterhouse ◽  
L. C. Roger ◽  
S. W. Ashworth
Keyword(s):  
Environmental Conditions ◽  
Death Rate ◽  
Farming Systems ◽  
Late Pregnancy ◽  
Scant Attention ◽  
Hill Farming ◽  
Poor Nutrition

Lamb mortality is high in hill farming systems. This is not a new phenomenon. Orr and Fraser (1932) reported losses of lambs between birth and weaning of over 30% and indeed an annual ewe death rate of up to 24%.Poor nutrition, of both macro- and micro-nutrients, is a prime cause of this problem exaggerated by difficult environmental conditions at the time of birth. Improved nutrition during late pregnancy was believed to be the most important (Wallace, 1948) and nutrition during mid pregnancy received scant attention. However, applied experiments with mid-pregnancy feeding of hill ewes (Milne, 1984; Waterhouse and McClelland, 1987) showed very significant effects of better nutrition during this period. The present paper summarizes the implementation of improved mid-pregnancy nutrition in a monitored systems study, associated with changes in management in late pregnancy made possible by assessment of foetal numbers from ultrasound pregnancy scanning.

Reproduction affects flight activity in female and male Daubenton’s bats, Myotis daubentoni

2007 ◽  
Vol 85 (5) ◽  
pp. 653-664 ◽  
Author(s):  
M. Dietz ◽  
E.K.V. Kalko
Keyword(s):  
Energy Demand ◽  
Late Summer ◽  
Climatic Conditions ◽  
Flight Activity ◽  
Adult Males ◽  
Reproductive Condition ◽  
Small Individual ◽  
Pregnant Females ◽  
Pregnancy And Lactation ◽  
Lactating Females

Nearly all mammals in the temperate zone breed in spring and summer when climatic conditions are favourable and food is abundant. Similar to other mammals, food requirements of female bats are particularly high during pregnancy and lactation and of males during spermatogenesis. Seasonal changes in energy demand and reproductive condition should therefore result in different foraging activity within and between sexes. This assumption was tested on 16 adult females and 13 adult males of the Palaearctic Daubenton’s bat, Myotis daubentoni (Kuhl, 1817), that were radio-tracked during pregnancy, lactation, and post-lactation periods. Pregnant females, as hypothesized, flew significantly longer (mean: 358.9 min; 70% of the night length) than males (mean: 228.5 min; 42.4% of the night length) during spring. In contrast, nightly flight time of lactating females decreased and was significantly less than that of pregnant females, but was similar to that of males during the same period. The longest flight times of males were registered during late summer when spermatogenetic activity is high. However, there were distinct differences in the use of foraging areas between female and male Daubenton’s bats. Female bats used small, individual foraging areas during pregnancy and lactation. The pattern was reversed in females after the young had been weaned and in males after they entered spermatogenesis. Overall, the results confirmed our proposition that flight activity reflects the higher energy demand and nutrition requirements in the different reproductive periods.

Evidence for luteotrophic and antiluteolytic actions of prolactin in rats with 5-day oestrous cycles

1988 ◽  
Vol 117 (3) ◽  
pp. 455-460 ◽  
Author(s):  
J. E. Sánchez-Criado ◽  
P. van der Schoot ◽  
J. Th. J. Uilenbroek
Keyword(s):  
Biological Activity ◽  
Corpus Luteum ◽  
Reproductive Cycle ◽  
Prolactin Secretion ◽  
Ovarian Cycle ◽  
Progesterone Secretion ◽  
Lh Secretion

ABSTRACT Injection of 1 mg bromocriptine at either 08.00 or 16.00 h on the day of oestrus in rats with 5-day oestrous cycles caused a reduction in the duration of progesterone secretion by the corpus luteum during dioestrous, and a shortening of the ovarian cycle by 1 day. These effects were not present when bromocriptine was injected at 08.00 h on the day of metoestrus. The effect of bromocriptine on progesterone secretion by the corpus luteum was reversed by neutralization of the biological activity of LH at dioestrus by injection of 0·5 ml anti-LH serum at 08.00 h at metoestrus. Injection of the antiserum alone prolonged progesterone secretion by the corpus luteum, but had no effect on the length of dioestrus. These results are interpreted as suggesting (1) that prolactin secretion on the afternoon of oestrus protects the corpus luteum of the rat ovarian cycle against the luteolytic effects of LH secretion during early dioestrus and (2) that prolactin stimulates progesterone secretion in the absence of such a luteolytic action. This response of the corpus luteum of the rat ovarian reproductive cycle to prolactin results in 5-day oestrous cycles. J. Endocr. (1988) 117, 455–460

Performance of interior spruce seedlings treated with abscisic acid analogs

1996 ◽  
Vol 26 (12) ◽  
pp. 2061-2070 ◽  
Author(s):  
Steven C. Grossnickle ◽  
Raymund S. Folk ◽  
Suzanne R. Abrams ◽  
David I. Dunstan ◽  
Patricia A. Rose
Keyword(s):  
Environmental Conditions ◽  
Stomatal Closure ◽  
Frozen Storage ◽  
Net Photosynthesis ◽  
Severe Drought ◽  
Bud Break ◽  
Root Temperature ◽  
Interior Spruce ◽  
Moderate Drought ◽  
Aba Analogs

This research examined the performance of interior spruce (Piceaglauca (Moench) Voss × Piceaengelmannii Parry ex Engelm.) seedlings, each group treated with one of nine abscisic acid (ABA) analogs, during the initial stages of seedling establishment under a range of environmental conditions. Interior spruce seedlings were removed from frozen storage, ABA analog treatments were immediately applied, and seedlings were tested under low root temperature or moderate drought cycle conditions. Alternatively, seedlings were removed from frozen storage and held until bud break had occurred before ABA analog treatments were applied. These seedlings were then tested under severe drought or optimum environmental conditions. ABA analog 1, followed by ABA analog 2, had the most consistent performance of the nine tested ABA analogs under all combinations of environmental test conditions. These ABA analogs reduced needle conductance for 7–9 days when seedlings were tested under low root temperature conditions with only a reduction in net photosynthesis on the first day of testing. During three successive moderate drought cycles, seedlings treated with ABA analogs 1 and 2 had partial stomatal closure, thereby increasing mean shoot water potential by around 50%. During a severe drought, ABA analog 1 caused partial stomatal closure, which allowed seedlings to maintain a mean shoot water potential of greater than −3.0 MPa and a positive net photosynthesis up to 8 days longer than control seedlings. Under optimum environmental conditions, ABA analogs 1 and 2 reduced needle conductance for up to 7 days, with net photosynthesis reduced for 1 day. Root growth was not adversely affected in seedlings treated with any of the ABA analogs prior to bud break. However, when seedlings were treated after bud break, all ABA analogs reduced growth of long roots (>4.0 cm) by approximately 60%. ABA analogs 1 and 2 delayed bud break by 4 days, when compared with control seedlings. Results are discussed in reference to the establishment process of spruce seedlings on reforestation sites.

scholarly journals Reproductive cycle of the bivalve, Lima scabra (Pterioida: Limidae):" and its association with environmental conditions

1969 ◽  
pp. 411-418
Author(s):  
César J Lodeiros ◽  
John H Himmelman
Keyword(s):  
Reproductive Cycle ◽  
Environmental Conditions

We examined the reproductive cycle of a,tropical bivalvé; the fire sdallop Lima (Ctenoides) scabra (Born, 1778), over a 14 months period in the Golfo de Cariaco, Venezuelá, and the' assooiation of gonadal gtowth

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