scholarly journals Photoperiod and its relationship to sheep reproduction

2021 ◽  
Author(s):  
Anayansi Ivette Ramírez Ramírez ◽  
Tania Arellano Lezama ◽  
Zadi Méndez Roblero1 ◽  
Guadalupe Idilia Delgado Tiburcio ◽  
Jaime Gallegos-Sánchez
Keyword(s):  
Animal Species ◽  
Reproductive Activity ◽  
Early Spring ◽  
Climatic Conditions ◽  
Day Length ◽  
Late Winter ◽  
Environmental Cues ◽  
Factors Affecting ◽  
Common Process ◽  
Almost Continuous

Objective: To describe the seasonal variations throughout the year (day length), as one of the main environmental cues used by ewes to determine the most favorable time for breeding. Design/methodology/approach: A description of the main factors affecting ewe reproduction (photoperiod, suckling, postpartum period, nutrition, sociosexual effects) was assessed by a review of documentary information. Results: The inhibition of reproductive activity during one time of the year is a common process in most animal species to prevent births from occurring at an unfavorable time for the survival of the offspring. The seasonality of reproduction (northern latitude) allows births to occur in late winter or early spring when climatic conditions are the most favorable for the offspring development. Limitations/implications: The duration of the anestrus season (seasonal or postpartum) is influenced by the photoperiod and other factors. In Mexico, a small percentage of Criollo and Pelibuey ewes show a short duration of seasonal anestrus; that is, they show almost continuous annual reproductive activity. Therefore, to improve the reproductive efficiency of ewes, it is important to precisely determine the factors that affect their reproduction to improve management and increase the profits in the production units. Findings/Conclusions: Photoperiod is the main environmental factor regulating the annual reproductive cycle of the ewes, it occurs through very complex and varied mechanisms that communicate the visual system with the gonads through nervous and endocrine pathways.

Cyclical Changes in the Distribution of the Testis Lipids of a Teleost Fish, Esox lucius

1957 ◽  
Vol s3-98 (41) ◽  
pp. 79-88
Author(s):  
B. LOFTS ◽  
A. J. MARSHALL
Keyword(s):  
Maximum Size ◽  
Early Spring ◽  
Day Length ◽  
Endocrine Function ◽  
Late Winter ◽  
Length Of Day ◽  
Spring Period ◽  
Sequence Of Events ◽  
Rhythmical Activity ◽  
Gradual Disappearance

A study of the cyclical changes in the distribution of testis lipids in the pike reveals a sequence of events comparable with that occurring in seasonal birds. These events include the post-nuptial appearance of cholesterol-positive lipid material which accumulates within the seminiferous lobules, and its subsequent gradual disappearance. A lipid cycle occurs also in the lobule walls, where apparently fibroblasts, in the absence of a true secretory interstitium, become glandular and probably take on an endocrine function. These ‘lobule boundary cells’ seasonally accumulate cholesterol-positive cytoplasmic lipids which suddenly become depleted at the time of the annual pre-spawning assembly. The pike differs from wild birds in the ‘timing’ of such rhythmical activity. In birds, despite a rapid post-nuptial interstitial regeneration, the tubule cholesterol lingers until spermatogenesis begins during the following late winter or spring. In the poikilothermous pike, on the other hand, the next spermatogenesis begins almost immediately (in June, when the temperature of the water is still rising). It continues without interruption while the length of day and later the temperature decrease, until the testis reaches its maximum size in December. ‘Lobule boundary cells’ start to become lipoidal in September, at a time of high temperature but decreasing day-length. The cells are fully charged by December. Both tubules and gland-cells now become inactive. Then in April at the spring period of increasing day-length, and immediately a iter water temperature starts to rise, the boundary cells begin to secrete and the prespawning assembly occurs. This is followed by the shedding of spermatozoa later in the month or early in May. The only period of true inactivity is at the height of spermatogenesis during mid-winter and early spring.

The biology of Harveyella mirabilis (Cryptonemiales, Rhodophyceae). IV. Life history and phenology

1976 ◽  
Vol 54 (3-4) ◽  
pp. 281-292 ◽  
Author(s):  
Lynda J. Goff ◽  
Kathleen Cole
Keyword(s):  
Water Temperature ◽  
Seawater Temperature ◽  
Environmental Parameters ◽  
Late Summer ◽  
Early Spring ◽  
Day Length ◽  
Late Winter ◽  
Temperature Sensitive ◽  
The North ◽  
The North Pacific

A 20-month field study of the reproductive biology of the parasitic red alga Harveyella mirabilis was undertaken to investigate the effects of environmental parameters on the reproductive periodicity of Harveyella in the intertidal habitat. In the northeast Pacific, tetraspores have been observed in the late winter - early spring; apparently they are produced in response to increased available sunlight and water temperature. Gametogenesis appears to be temperature sensitive; it occurs between a narrow temperature range (9–11 °C). Carpospores are produced in the late summer when both water temperature and day length reach a peak. The phenology of H. mirabilis in the North Atlantic differs from that which is observed in the North Pacific in the timing of gametogenesis and carposporogenesis. The significance of this is discussed in relation to the possible effects of differences in seawater temperature on gametogenesis.

scholarly journals Cupressaceae Pollen in the City of Évora, South of Portugal: Disruption of the Pollen during Air Transport Facilitates Allergen Exposure

Forests ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 64
Author(s):  
Ana Galveias ◽  
Ana R. Costa ◽  
Daniele Bortoli ◽  
Russell Alpizar-Jara ◽  
Rui Salgado ◽  
...  
Keyword(s):  
Wind Speed ◽  
Ornamental Plants ◽  
Global Solar Radiation ◽  
Early Spring ◽  
Back Trajectory ◽  
Late Winter ◽  
Hysplit Model ◽  
Back Trajectories ◽  
Factors Affecting ◽  
Back Trajectory Analysis

Research Highlights: Daily airborne Cupressaceae pollen disruption ranged from 20 to 90%; relative humidity (RH), rainfall and atmospheric pressure (AtP) were the major meteorological determinants of this phenomenon. Background and Objectives: Cupressaceae family includes several species that are widely used as ornamental plants pollinating in late winter-early spring and might be responsible for allergic outbreaks. Cupressaceae pollen disruption may favour allergen dissemination, potentiating its allergenicity. The aim of this work was to characterize the Cupressaceae pollen aerobiology in Évora, South of Portugal, in 2017 and 2018, particularly the pollen disruption, and to identify the meteorological parameters contributing to this phenomenon. Materials and Methods: Pollen was collected using a Hirst type 7-day pollen trap and was identified following the standard methodology. Temperature, RH, rainfall, global solar radiation (Global Srad), AtP, wind speed and direction were obtained from a weather station installed side-by-side to the Hirst platform. Back trajectories (12-h) of air masses arriving at Évora were calculated using the HYSPLIT model. Results: Cupressaceae pollen index was higher in 2017 compared to 2018 (>5994 and 3175 pollen/m3, respectively) and 36 ± 19% (2017) and 59 ± 23% (2018) of the pollen was disrupted. Higher levels of disrupted pollen coincided with RH > 60% and rainfall. Temperature, Global Srad and AtP correlated negatively with pollen disruption. Wind speed and wind direction did not significantly correlate with pollen disruption. Intra-diurnal pollen pattern peaked between 9:00 am–2:00 pm, suggesting local origin, confirmed by the back trajectory analysis. Intra-diurnal pollen disruption profile followed hourly pollen pattern and it negatively correlated with AtP, temperature and Global Srad but was uncorrelated with RH. Conclusions: The results suggest that RH, rainfall and AtP are the main factors affecting airborne Cupressaceae pollen integrity and in conjunction with daily pollen concentration may be used to predict the risk of allergy outbreaks to this pollen type.

Factors affecting the productivity of irrigated annual pastures. 1. Time of first irrigation in late summer-early autumn

1986 ◽  
Vol 26 (3) ◽  
pp. 297 ◽  
Author(s):  
CR Stockdale
Keyword(s):  
Nitrogen Content ◽  
Irrigation Treatment ◽  
Subterranean Clover ◽  
Late Summer ◽  
Early Spring ◽  
The Other ◽  
Late Winter ◽  
Factors Affecting ◽  
Autumn And Winter ◽  
Clover Content

The influence of time of first irrigation (mid-February, early March, or late March) on the productivity of an annual pasture was studied for 3 years in northern Victoria. Beginning the irrigation of annual pastures in late summer instead of at the normal time of late March- April provided additional herbage in autumn and winter and did not adversely affect herbage production in late winter-early spring; up to 2.3 t/ha DM of additional herbage was obtained by mid June and 4.3 t/ha DM over the whole season. Earlier irrigation also increased the subterranean clover content of the pasture, resulting in herbage that was lower in digestibility and higher in nitrogen content than that in the other treatments. The benefit of early irrigation in increasing clover content may be offset by invasion by weeds. In this experiment, a potential weed problem in the earliest irrigation treatment appeared at the beginning of year 3.

scholarly journals The Role of Melatonin in Ewes Reproduction: a Review

2019 ◽  
Vol 12 (2) ◽  
Keyword(s):  
Physiological Role ◽  
Early Spring ◽  
Day Length ◽  
Late Winter ◽  
Seasonal Reproduction ◽  
Gnrh Secretion ◽  
Reproductive Activities ◽  
Short Days

This review was assigned to illustrate the melatonin (MLT) effect on reproduction in sheep (ewes). However, the pathway by which MLT charge the seasonal reproduction are imperfectly understood in sheep, the researchers consents that MLT regulates reproduction under influence of day length (photoperiod) to guarantee that birth happen in appropriate date of the year, it’s called neuro-endocrine process. This mechanism mediates by the pineal hormone (MLT). The major role of MLT in ewes is to translate the photo signals into endocrine pulses (gonadotropin-releasing hormone (GnRH) secretion) at the end of the retino-pineal pathway. In sheep, the MLT receptors distributed in premammillary hypothalamus (PMH), pituitary gland and Suprachiasmatic nucleus (SCN), therefore, many brain loci are participating for MLT pathways to modify the seasonal reproduction. Melatonin stimulates GnRH secretion through effect in different regions and neurons in hypothalamus such as a pre-mammillary nucleus, Arcuate and several factors like kisspeptin, RF-amide related peptide-3 (RFRP-3) and Tyrosine Hydroxylase (TH). In addition, its indirectly control prolactin (PRL) output via an effect on Tuberalin release, which is mediate the mechanism of MLT activity on pituitary PRL secretion and regulate his seasonal cyclicity. The alter in day length is the principle ecological factor that control the breeding in seasonal domestic animals. Several reproductive activities are related to short days and begin during autumn when the day becomes short and a decline in temperature (short-day breeder). While expanding in the duration of light lead to a cessation in reproduction activities during late winter and early spring. In conclusion, according to the major physiological role of MLT, it can be used in different aspects in ewes reproduction industry such as induce oestrus, increment the ovulation rate and In vitro embryo production.

Factors affecting competition between subterranean clover and a barley cover crop

1973 ◽  
Vol 13 (60) ◽  
pp. 56 ◽  
Author(s):  
AA McGowan ◽  
WA Williams
Keyword(s):  
Seed Production ◽  
Light Transmission ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Early Spring ◽  
Late Winter ◽  
Factors Affecting ◽  
Competition For Light ◽  
Clover Seed ◽  
Main Factor

Subterranean clover (Trifolium subterraneum) was sown with barley (Hordeum vulgare) in autumn under a variety of management treatments. Clover seed production was increased when barley emergence was delayed by seed treatment with CCC or paraffin wax, or by delayed sowing, when barley seeding rates were reduced, or when barley was clipped in late winter. The main factor limiting growth of the undersown clover was competition for light, especially in late winter and early spring when light transmission through the barley crop dropped below 60 per cent. Despite a dry spring, interspecific competition for moisture evidently imposed very little restriction on clover growth and seed production. Competition for nitrogen may have occurred earlier in the season.

scholarly journals Intermediate-duration day lengths unmask reproductive responses to nonphotic environmental cues

2009 ◽  
Vol 296 (5) ◽  
pp. R1613-R1619 ◽  
Author(s):  
Matthew J. Paul ◽  
Jerome Galang ◽  
William J. Schwartz ◽  
Brian J. Prendergast
Keyword(s):  
Pubertal Development ◽  
Late Summer ◽  
Early Spring ◽  
Day Length ◽  
Environmental Cues ◽  
Local Conditions ◽  
Siberian Hamsters ◽  
Reproductive Axis ◽  
And Behavior

Many animals time their breeding to the seasons, using the changing day length to forecast those months when environmental conditions favor reproductive success; in Siberian hamsters ( Phodopus sungorus), long summer days stimulate, whereas short winter days inhibit, reproductive physiology and behavior. Nonphotic environmental cues are also thought to influence the timing of breeding, but typically their effects on reproduction are minor and more variable under categorically long and short photoperiods. We hypothesized that the influence of nonphotic cues might be more prominent during intermediate photoperiods (early spring and late summer), when day length is an unreliable predictor of year-to-year fluctuations in food availability. In hamsters housed in an intermediate photoperiod (13.5 h light/day), two nonphotic seasonal cues, mild food restriction and same-sex social housing, induced gonadal regression, amplified photoperiod history-dependent reproductive responses to decreasing day lengths, and prevented pubertal development indefinitely. These cues were entirely without effect in hamsters maintained under a long photoperiod (16 h light/day). Thus intermediate photoperiods reveal a heightened responsiveness of the reproductive axis to nonphotic cues. This photoperiod-dependent efficacy of nonphotic cues may explain how animals integrate long-term photic and short-term nonphotic cues in nature: intermediate day lengths open a seasonal window of increased reproductive responsiveness to nonphotic cues at a time when such cues may be of singular relevance, thereby allowing for precise synchronization of the onset and offset of the breeding season to local conditions.

Genetic linkage mapping for molecular dissection of chilling requirement and budbreak in apricot (Prunus armeniaca L.)

Genome ◽  
2009 ◽  
Vol 52 (10) ◽  
pp. 819-828 ◽  
Author(s):  
Bode A. Olukolu ◽  
Taly Trainin ◽  
Shenghua Fan ◽  
Chittaranjan Kole ◽  
Douglas G. Bielenberg ◽  
...  
Keyword(s):  
Interval Mapping ◽  
Early Spring ◽  
Prunus Armeniaca ◽  
Climatic Conditions ◽  
High Density ◽  
Late Winter ◽  
Phenotypic Variance ◽  
Chilling Requirement ◽  
Density Maps ◽  
Spring Frosts

Commercial production of apricot is severely affected by sensitivity to climatic conditions, an adaptive feature essential for cycling between vegetative or floral growth and dormancy. Yield losses are due to late winter or early spring frosts and inhibited vegetative or floral growth caused by unfulfilled chilling requirement (CR). Two apricot cultivars, Perfection and A.1740, were selected for high and low CR, respectively, to develop a mapping population of F1 individuals using a two-way pseudo-testcross mapping strategy. High-density male and female maps were constructed using, respectively, 655 and 592 markers (SSR and AFLP) spanning 550.6 and 454.9 cM with average marker intervals of 0.84 and 0.77 cM. CR was evaluated in two seasons on potted trees forced to break buds after cold treatments ranging from 100 to 900 h. A total of 12 putative CR quantitative trait loci (QTLs) were detected on six linkage groups using composite interval mapping and a simultaneous multiple regression fit. QTL main effects of additive and additive × additive interactions accounted for 58.5% ± 6.7% and 66.1% ± 5.8% of the total phenotypic variance in the Perfection and A.1740 maps, respectively. We report two apricot high-density maps and QTLs corresponding to map positions of differentially expressed transcripts and suggested candidate genes controlling CR.

Impact of climatic conditions on the parameters of failure flow of military vehicles

2021 ◽  
pp. 095440702110202
Author(s):  
Nikolaj Dobrzinskij ◽  
Algimantas Fedaravicius ◽  
Kestutis Pilkauskas ◽  
Egidijus Slizys
Keyword(s):  
Climatic Factors ◽  
Armed Forces ◽  
Climatic Conditions ◽  
Operating Conditions ◽  
Technical Equipment ◽  
Factors Affecting ◽  
Military Vehicles ◽  
Equipment Reliability ◽  
Number Of Factors ◽  
The Impact

Relevance of the article is based on participation of armed forces in various operations and exercises, where reliability of machinery is one of the most important factors. Transportation of soldiers as well as completion of variety of tasks is ensured by properly functioning technical equipment. Reliability of military vehicles – armoured SISU E13TP Finnish built and HMMWV M1025 USA built were selected as the object of the article. Impact of climatic conditions on reliability of the vehicles exploited in southwestern part of the Atlantic continental forest area is researched by a case study of the vehicles exploitation under conditions of the climate of Lithuania. Reliability of military vehicles depends on a number of factors such as properties of the vehicles and external conditions of their operation. Their systems and mechanisms are influenced by a number of factors that cause different failures. Climatic conditions represent one of the factors of operating load which is directly dependent on the climate zone. Therefore, assessment of the reliability is started with the analysis of climatic factors affecting operating conditions of the vehicles. Relationship between the impact of climatic factors and failure flow of the vehicles is presented and discussed.

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