The effects of temperature and daylength on the reproductive physiology of the viviparous seaperch, Cymatogaster aggregata Gibbons

1968 ◽  
Vol 46 (6) ◽  
pp. 1207-1219 ◽  
Author(s):  
John P. Wiebe
Keyword(s):  
Late Summer ◽  
Late Pregnancy ◽  
Early Summer ◽  
Reproductive Physiology ◽  
Cold Temperature ◽  
Late Winter ◽  
Warm Temperature ◽  
Cold Temperatures ◽  
Effects Of Temperature ◽  
Long Photoperiod

The effects of temperature and photoperiod on the reproductive physiology of Cymatogaster aggregata are examined experimentally and related to the conditions in nature. In males an increasing or long photoperiod in late winter, spring, or early summer results in spermatogenesis, development of secondary sex structures, and reproductive behavior; warm temperatures markedly enhance these processes. The cold temperature and short photoperiod of the winter months promote testicular restitution and growth of spermatogonia.In females, oocyte formation is enhanced by the warm temperature (and perhaps decreasing photoperiod) of late summer and eariy autumn, while oocyte maturation is fostered by the cold temperatures of early winter. Early gestation requires a cold temperature but during late pregnancy a warm temperature will enhance growth of embryos.

Influence of season and of reproductive status on the wool growth of Merino ewes in arid environment

1978 ◽  
Vol 18 (94) ◽  
pp. 648 ◽  
Author(s):  
H Hawker ◽  
JP Kennedy
Keyword(s):  
New South ◽  
New South Wales ◽  
Late Summer ◽  
Late Pregnancy ◽  
Arid Environment ◽  
Late Winter ◽  
Early Lactation ◽  
Wool Growth ◽  
South Wales ◽  
Australian Merino

At Fowlers Gap, an arid saltbush environment in far western New South Wales, the wool growth of South Australian Merino ewes was measured at intervals of about ten weeks for three years. Highest rates of wool growth on dry ewes were recorded each year in late winter (1 0.8, 14.9, 15.7 g day-1) and lowest in late summer (6.0, 7.7, 10.7 g day-1). Changes in the rate of wool growth were associated with changes in pastoral conditions in two of the three years. Relative to dry ewes, the rate of wool growth of wet ewes was reduced by 9 to 24 per cent in late pregnancy, 21 to 43 per cent in early lactation and 3 to 26 per cent in late lactation. The reduction was inversely related to current pasture growth.

Arctic summer sea-ice SAR signatures, melt-season characteristics, and melt-pond fractions

Polar Record ◽  
1997 ◽  
Vol 33 (185) ◽  
pp. 101-112 ◽  
Author(s):  
M. O. Jeffries ◽  
K. Schwartz ◽  
S. Li
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Late Summer ◽  
Beaufort Sea ◽  
Early Summer ◽  
The Arctic ◽  
Late Winter ◽  
Melt Pond ◽  
Melt Ponds ◽  
The Arctic Ocean

AbstractVariations in multiyear sea-ice backscatter from the synthetic aperture radar (SAR) aboard the ERS-1 satellite are interpreted in terms of melt-season characteristics (onset of melt in spring and of freeze-up in autumn, and the duration of the snow-decay period, the melt season, and the melt-pond season) from late winter to early autumn 1992 in two regions of the Arctic Ocean: the northeastern Beaufort Sea adjacent to the Queen Elizabeth Islands in the Canadian high Arctic and the western Beaufort Sea north of Alaska. In the northeastern Beaufort Sea, the onset of melt occurs later, and the periods of snow-cover decay and the occurrence of melt ponds are shorter than in the western Beaufort Sea. These melt-season characteristics of each area are consistent with previous observations that the northeastern Beaufort Sea has one of the most severe summer climates in the Arctic Ocean. A model, which assumes that the backscatter from multiyear floes is the sum of backscatter from bare ice and melt ponds, is used to derive the melt-pond fraction during the summer. The results show that melt-pond fractions decrease from an early-summer maximum of about 60% to a late-summer minimum around 10%. The magnitude of the melt-pond fractions and their decline during the summer is consistent with previous, more qualitative data. The SAR model, which gives melt-pond fractions with lower variability and less uncertainty than previous data, offers an improved approach to the reliable estimation of the areal extent of water on ice floes. Suggestions for further improvement of the model include accounting for the consequences of wind-speed variations, summer snowfall, and freeze/thaw cycles and their effects on melt-pond and ice-surface roughness.

scholarly journals Distribution, abundance and biology of ringed seals (Phoca hispida): an overview

1998 ◽  
Vol 1 ◽  
pp. 9 ◽  
Author(s):  
Randall R Reeves
Keyword(s):  
Polar Bear ◽  
Late Summer ◽  
Early Summer ◽  
Ringed Seal ◽  
Late Spring ◽  
Late Winter ◽  
Polar Cod ◽  
World Population ◽  
Phoca Hispida ◽  
Ringed Seals

The ringed seal (Phoca hispida) has a circumpolar Arctic distribution. Because of its great importance to northern communities and its role as the primary food of polar bears (Ursus maritimus) the ringed seal has been studied extensively in Canada, Alaska, Russia, Svalbard and Greenland as well as in the Baltic Sea and Karelian lakes. No clear-cut boundaries are known to separate ringed seal stocks in marine waters. Adult seals are thought to be relatively sedentary, but sub-adults sometimes disperse over long distances. Stable ice with good snow cover is considered the most productive habitat although production in pack ice has been little studied. Populations appear to be structured so that immature animals and young adults are consigned to sub-optimal habitat during the spring pupping and breeding season. Annual production in ringed seal populations, defined as thepup percentage in the total population after the late winter pupping season, is probably in the order of 18-24%. Most estimates of maximum sustainable yield are in the order of 7%.The world population of ringed seals is at least a few million. Methods of abundance estimation have included aerial surveys, dog searches and remote sensing of lairs and breathing holes, acoustic monitoring, correlation analysis by reference to sizes of polar bear populations, and inference from estimated energy requirements of bear populations. Aerial strip survey has been the method of choice for estimating seal densities over large areas. Adjustment factors to account for seals not hauled out at the time of the survey, for seals that dove ahead of the aircraft, and for seals on the ice within the surveyed strip but not detected by the observers, are required for estimates of absolute abundance.Male and female ringed seals are sexually mature by 5-7 years of age (earlier at Svalbard). Pupping usually occurs in March or early April and is followed by 5-7 weeks of lactation. Breeding takes place in mid to late May, and implantation is delayed for about 3 months. In at least some parts of their range, ringed seals feed mainly on schooling gadids from late autumn through early spring andon benthic crustaceans and polar cod (Boreogadus saida) from late spring through summer. Little feeding is done during the moult, which takes place in late spring and early summer. Pelagic crustaceans offshore and mysids inshore become important prey in late summer and early autumn in some areas. Ringed seals have several natural predators, the most important of which is the polar bear in most arctic regions. Arctic foxes (Alopex lagopus) kill a large percentage of pups in someareas.From a conservation perspective, the ringed seal appears to be secure. Levels of exploitation of arctic populations have usually been considered sustainable, except in the Okhotsk Sea. Large fluctuations in production of ringed seals in the Beaufort Sea and Amundsen Gulf are thought to be driven by natural variability in environmental conditions. While concern has been expressed about thepotential impacts of industrial activity and pollution on ringed seals, such impacts have been documented only in limited areas. Because of their ubiquitous occurrence and availability for sampling, ringed seals are good subjects for monitoring contaminant trends in Arctic marine food chains. 

Seasonal changes in activity patterns and the adaptive value of haying in pikas (Ochotona princeps)

1983 ◽  
Vol 61 (2) ◽  
pp. 411-416 ◽  
Author(s):  
Douglas A. Conner
Keyword(s):  
Surface Activity ◽  
Seasonal Changes ◽  
Activity Patterns ◽  
Winter Season ◽  
Late Summer ◽  
Early Summer ◽  
Cold Temperatures ◽  
Vegetation Growth ◽  
Ochotona Princeps ◽  
Early Fall

Seasonal changes in the performance of four behaviors, perching, haying, feeding, and surface activity were studied in two populations of North American pikas (Ochotona princeps) living in Colorado. During late summer and early fall (July–September), haying, the gathering of meadow vegetation followed by storing it in their talus territories, made up almost 55% of the pikas' surface activity. After haying ceased, pikas continued to feed in the meadows until snowpack, cold temperatures, and the absence of surface vegetation made this impossible. Beginning in February, individuals remained under the snowpack feeding on vegetation from their hay piles and on lichens available below the snow. Surface activity was not seen again until May when spring vegetation began to appear. Haying appears to be an adaptive response to environmental unpredictability. Hay piles most likely become critical for survival when harsh weather prevents surface foraging and(or) delays the emergence of new vegetation growth in the spring or early summer. It is suggested that the evolution of territoriality in pikas is related to the need to gather sufficient vegetation to serve as a potential winter food supply during years when the winter season is unusually harsh or prolonged.

Environmental Influence on Bentgrass Treated with Silvex

Weed Science ◽  
1968 ◽  
Vol 16 (2) ◽  
pp. 193-196 ◽  
Author(s):  
Lloyd M. Callahan ◽  
Ralph E. Engel ◽  
Richard D. Ilnicki
Keyword(s):  
Environmental Influence ◽  
Late Summer ◽  
Creeping Bentgrass ◽  
Early Summer ◽  
Low Ph ◽  
Agrostis Palustris ◽  
High Moisture ◽  
Early Fall ◽  
Moisture Conditions ◽  
Long Photoperiod

Colonial bentgrass (Agrostis tenuis Sibth) and creeping bentgrass (Agrostis palustris Huds) exhibited the most tolerance to 1/2, 1, 1 1/2, and 3 lb/A of 2-(2,4,5-trichlorophenoxy)propionic acid (silvex) when grown under cool temperatures, a long photoperiod, and a low pH medium. Injury from treatments was slight to moderate when applied from early to mid-spring, severe when made from late spring to early summer, and very severe when made from late summer to early fall. Silvex appeared to cause the most injury at the 1 and 1 1/2 lb/A rates. Injury was much less from the lower rate of 1/2 lb/A. Root fructosan concentrations decreased with increasing rates under cool temperatures and increased with increasing rates under high temperatures. Bentgrass appeared to tolerate silvex treatments better under low available moisture conditions than under high moisture levels.

The rice rat Oryzomys palustris in a Delaware salt marsh: annual reproductive cycle

1993 ◽  
Vol 71 (7) ◽  
pp. 1457-1460 ◽  
Author(s):  
Kent E. Edmonds ◽  
Milton H. Stetson
Keyword(s):  
Salt Marsh ◽  
Breeding Season ◽  
Seasonal Pattern ◽  
Late Summer ◽  
Early Summer ◽  
Late Winter ◽  
Annual Reproductive Cycle ◽  
Monthly Basis ◽  
Lactating Females ◽  
Oryzomys Palustris

A population of the rice rat Oryzomys palustris inhabiting the Canary Creek salt marsh in Lewes, Delaware, was sampled on a monthly basis from September 1988 to December 1990. Males were assigned to the following age-classes on the basis of body mass: juveniles, 0 – 30 g; subadults, 31 – 50 g; adults, 51 g or greater. Testicular mass exhibited a seasonal pattern with lowest adult values in late autumn and early winter and peak values in late spring and early summer. Females showed similar patterns in uterine mass and vaginal patency. Pregnant and (or) lactating females were found from March to late September. The data suggest that the breeding season of the rice rat in southern Delaware begins in late winter and extends into late summer. Favorable environmental conditions may extend the breeding season for some individuals into autumn.

EFFECTS OF TEMPERATURE ON YIELDS AND HYDROLYZABLE CARBOHYDRATE CONTENT OF ALFALFA AND TIMOTHY SEEDLINGS

1967 ◽  
Vol 47 (5) ◽  
pp. 523-531 ◽  
Author(s):  
P. Dermine ◽  
M. Hidiroglou ◽  
H. A. Hamilton
Keyword(s):  
Growth Rate ◽  
Low Temperature ◽  
Sugar Content ◽  
Strong Dependence ◽  
Growing Season ◽  
Cold Temperature ◽  
Cold Period ◽  
Warm Temperature ◽  
Northern Ontario ◽  
Effects Of Temperature

Alfalfa and timothy seedlings were exposed to four temperature treatments, simulating conditions in an average growing season in northern Ontario. Highest yields were recorded under continuous warm temperature (26.7 °C day, 15.6 °C night) and the lowest under continuous cold temperature (15.6 °C day, 4.4 °C night). Warm temperature conditions followed by a cold period decreased growth rate, the effect being more severe on alfalfa than on timothy. Growth was slower at first for timothy than for alfalfa, but timothy growth rate eventually exceeded that of alfalfa.Alfalfa root weights showed a strong dependence on temperature and were closely related to herbage yields. Timothy root weights demonstrated a smaller reaction to temperature and little relationship with herbage production. Shoot: root ratios were higher in timothy than in alfalfa but showed no consistent relationship with temperature.Timothy had a higher hydrolyzable-sugar content than alfalfa. Continuous low temperature resulted in the lowest sugar content in both species, but exposure to low temperature following a warm period gave the highest content.

Population and demographic patterns of rabbits (Oryctolagus cuniculus) at Roxby Downs in arid South Australia and the influence of rabbit haemorrhagic disease

1998 ◽  
Vol 25 (6) ◽  
pp. 655 ◽  
Author(s):  
Zoë Bowen ◽  
John Read
Keyword(s):  
Oryctolagus Cuniculus ◽  
South Australia ◽  
Late Summer ◽  
Early Summer ◽  
Myxoma Virus ◽  
Late Winter ◽  
Virus Vectors ◽  
Rabbit Haemorrhagic Disease ◽  
Demographic Patterns ◽  
Haemorrhagic Disease

Rabbit populations and demography were surveyed at Roxby Downs in arid South Australia from 1989 to 1997. Rabbit numbers typically peaked in late summer following breeding from late winter to early summer. After initial declines attributable to burrow flooding and increased populations of virus vectors, rabbit numbers increased by approximately 400% after significant rains. Introductions of Spanish rabbit flea, a vector of Myxoma virus, did not influence rabbit numbers but rabbit haemorrhagic disease (RHD) had a dramatic and sustained influence on rabbit numbers. The optimum times for release of RHD are discussed.

Effects of Dried Distillers’ Grains Cube Supplementation for Steers Grazing Introduced Pastures on Animal Performance and Forage Production

2021 ◽  
Vol 99 (Supplement_2) ◽  
pp. 12-13
Author(s):  
Jordan Adams ◽  
Rodney Farris ◽  
Scott Clawson ◽  
Earl Ward ◽  
Paul Beck
Keyword(s):  
Festuca Arundinacea ◽  
Statistical Power ◽  
Cynodon Dactylon ◽  
Animal Health ◽  
Late Summer ◽  
Early Summer ◽  
Distillers Grains ◽  
Forage Production ◽  
Trenbolone Acetate ◽  
Dried Distillers Grains

Abstract We evaluated the effects of supplementing dried distillers’ grains cubes (DDGS) and re-implantation of steers (n = 149; BW = 238 ± 13.8 kg) grazing tall fescue (Festuca arundinacea)/bermudagrass (Cynodon dactylon) pastures (n = 9 pastures, 7.2 ± 2.90 ha) from 14 April to 17 September 2020 (n = 155 d) in a split-plot design on steer performance and forage production. Main plot supplemental treatments (n = 3 pastures/treatment) included 1) Fertilized Control (FC), no supplementation on fertilized pastures (112 kg N/ha); 2) Fertilized Supplement (FS), supplemental DDGS fed at 2.9 kg 3-d/wk on fertilized pastures; and 3) Supplement (S), supplemented DDGS at 0.75% BW/d on unfertilized pastures prorated for 5-d/wk feeding. Steers were previously implanted during receiving with 40 mg trenbolone acetate and 8 mg estradiol (REV-G; Revalor G, Merck Animal Health). On July 7, steers in each pasture were randomly assigned to one of three re-implant treatments: 1) no re-implant; 2) REV-G; or 3) 200 mg progesterone and 20 mg estradiol (Synovex S, Zoetis Animal Health). Steers in FS and S gained more (P < 0.01) than FC throughout the trial and final BW was greater (P < 0.01) for FS and S compared with FC. Unexpectedly, re-implanting had no effect on ADG (P = 0.57) or BW (P = 0.34), but statistical power may be lacking. Supplemental efficiency was greater in the late summer for FS (P = 0.05) compared to S. Fertilizing pastures in FS and FC did not affect biomass (P = 0.39), however, CP was increased (P = 0.01) and acid and neutral detergent fibers tended to decrease (P = 0.06) relative to S in the early summer (April, May, June, and July), but did not differ in late summer (August and September). Based upon our analysis, DDGS is a suitable supplement and can replace N fertilizer for steers grazing introduced pastures.

scholarly journals 179 Using a 100% Dried Distillers Grains Cube as a Supplement for Steers Grazing Mixed Grass Prairie in Oklahoma

2020 ◽  
Vol 98 (Supplement_2) ◽  
pp. 46-46
Author(s):  
Zane N Grigsby ◽  
Paul A Beck ◽  
Stacey A Gunter
Keyword(s):  
Animal Health ◽  
Late Summer ◽  
Estradiol Benzoate ◽  
Positive Control ◽  
Negative Control ◽  
Early Summer ◽  
Trenbolone Acetate ◽  
Mixed Grass Prairie ◽  
Mixed Grass ◽  
Main Plot

Abstract This research was conducted to determine effects of supplementation and implanting on BW gain by steers grazing mixed grass prairie (n = 12 pastures, 19.9 ± 0.7 ha) in northwest Oklahoma. Three main plot treatments were: 1) Negative Control (NC), no supplementation, 2) Positive Control (PC), supplemented with DDGS cubes, 1.8 kg/steer on alternate days in late summer, 3) High Supplement (HS), 1/3 increase in stocking rate with 0.75% BW supplemental DDGS cubes all season. Steers (n = 125, BW = 223.1 ± 23.2 kg) were stocked at 2.2 ha/steer for PC and NC, 1.3 ha/steer for HS. Grazing was from May 17 – September 27 (132 d). All steers were implanted with 200 mg progesterone and 20 mg estradiol benzoate (SYN, Synonvex S, Zoetis Animal Health) on May 17. On July 18 three reimplant treatments were applied: 1) no reimplant; 2) SYN; or 3) 40 mg trenbolone acetate and 8 mg estradiol (Revalor G, Merck Animal Health). Data were analyzed using the PROC MIXED in SAS as a split-plot experimental design. In early summer HS had 0.26 kg greater (P < 0.01) ADG than NC and PC. Late summer gains of PC were 0.33 kg/d more (P ≤ 0.01) than NC; and HS gained 0.49 and 0.16 kg/day more (P ≤ 0.04) than NC and PC, respectively. Gain per hectare for PC (46 kg/ha) were greater (P < 0.01) than NC (35 kg/ha) and more than doubled (P < 0.01) with HS (89 kg/ha). Reimplanting had no effect on ADG (P ≥ 0.28). Late season supplementation with PC resulted in supplemental efficiency of 2.7 kg supplement/kg added gain compared with NC. Increased stocking rates with season long supplementation in HS resulted in supplemental efficiency of 3.8 kg supplement/kg added gain per hectare. Based on these data, a 100% DDGS cube is an effective supplement option to increase BW gain during the late summer or increase carrying capacity and gain during the summer grazing period in northwestern Oklahoma.

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