Artificial Photoperiod Research Articles

Effect of environmental factors and changes in the body condition score on the onset of the breeding season in mares.

Several methods have been proposed to advance the onset of the breeding season in horses. Most of them are based on the exposure to an artificial lighting period combined with hormonal treatments. Mares exposed to an artificial photoperiod are most often housed indoors where the ambient temperature is often higher than the outside temperature. Mares held in barns are also exposed to different daylight intensities than horses kept outside, depending on the architecture. In the current study, we evaluated the impact of ambient temperature, daylight intensity and changes in body condition score (BCS) on the timing of first ovulation after winter anestrus in mares exposed to an artificial photoperiod. Mares (n=211) were housed in barns with different ambient temperature and daylight exposure but with the same artificial photoperiod exposure (except for a natural photoperiod control group). Artificial photoperiod as well as an increase in BCS over the winter significantly advanced the first spring ovulation. The BCS at the start and end of the anestrus period did not have an effect on the interval to first ovulation and neither did the modest increase in ambient temperature in the barn. However, a higher light intensity during the daytime significantly advanced the first spring ovulation. The results of this study suggest that exposure to more sunlight advances the onset of the breeding season. This effect is likely mediated through the biological effect of short wavelength blue light and its impact on melatonin suppression and biological rhythms. We suggest that greater/direct exposure to the blue light component of daylight improves the response to the artificial photoperiod. The results of the present study can further assist to optimize the conditions that lead to an efficient spring transition of breeding mares.

The Effect of Altrenogest Treatment Timing and Artificial Lighting on Hastening of Ovulation in Barren Mares

Background: The mares are seasonally polyestrous animals that regular ovulatory cycles of mares occur together with increasing day length. Exposure of mares to an artificial photoperiod is the most common and predictable technique that it is used to develop follicular activity early in the year. Follicle activity is minimal in mares during two winter months of January and February in Northern Hemisphere. The main objective of this study was to investigate efficacy of artificial lighting and timing of altrenogest treatment for hastening the ovulation in Thoroughbred mares.Materials, Methods & Results: One hundred and six Thoroughbred mares had different follicle sizes (< 30 mm) was evaluated under four groups. Mares undergoing only reproductive examination were control group Group I (n = 18). The mares has less than 30 mm in diameter folicle applied oral altrenogest (0.044 mg / bw, for 10 days) were grouped according to the month of application: Group II [February; n = 16], Group III [March; n = 57] and Group IV [April; n = 15]. Ultrasonographical examinations performed at the day of admission and repeated twice a week for 15 days. Naturel mating was planned considering to uterine edema (> 35 mm folicle size), and pregnancies were determined at 14, 28 and 50th day postovulation. Statisticaly, mean and standard deviations and general linear model procedure was performed on Minitab 17, and Anova was used to analysis of variance. The averages of the major variations were compared with the Tukey’s multiple comparison test. The factors effecting to pregnancy rate was analyzed by Chi-square test. Correlations were compared with the Pearson correlation test. The effect of initial months on the size of follicle diameter was found to be significant (P = 0.037). Artificial lighting had no effect on the initial follicle diameter (P = 0.919). The initial follicle diameter (P = 0.001) and artificial lighting (P = 0.026) had a significant effect on the time of follicle reaching in 35mm diameter. Initial follicle diameter (P = 0.001), treatment time (P = 0.000), light therapy (P = 0.026) and altrenogest application (P = 0.026) were found to be effective. Initial follicle diameter (P = 0.575), timing of treatment (P = 0.243), light therapy (P = 0.461) and application of altrenogest (P = 0.088) had no significant effect on the diameter of ovulatory follicle. There are positive correlations between the initial follicle diameter and follicle diameter at the end of treatment (P = 0.000; R = 0.399); There is a high positive correlation between the day of reaching 35mm diameter and ovulation day (P = 0.000; r = 0.777); there is a negative correlation between beginning follicle diameter and 35 mm diameter (P = 0.006; r = -0.266) and ovulation day (P = 0.000; r = -0.366). There was a negative correlation between the follicle diameter at the end of the treatment and the 35mm diameter (P = 0.000; r = -0.736) and the day of ovulation (P = 0.000; r = -0.628). These statistical results pointed out that timing of altrenogest treatment and artifial lighting had effectivity on hastening the ovulations in barren mares.Discussion: To evaluate the seasonal effect on follicle diameter, the measurement of the initial follicle diameters is important, which is smaller in February than the following months. The initial follicle diameter is effect on time to reach in 35 mm diameter and ovulation; however, in these mares, ovulation formes in a long time. Regarding the seasonal effect, the success of ovulation depends on treatment time in seasonal months. It is shown that short term altrenogest administration has not shortened interval to the posttreatment ovulation. As a limitation of this study, because there are not enough mares in control group, further studies should be planned for more evaluations.

Analyses of mathematical models for Yangzhou geese egg-laying curves

Mathematical models of the egg-laying curves for Yangzhou geese exposed to both natural and artificial photoperiods were established to optimise the parameters for maximising geese reproductive performance and for the development of precision feeding methods. With the natural photoperiod, egg-laying starts in autumn when daily photoperiod decreases, but accelerates after the winter solstice, and reaches the peak in spring when photoperiod increases. An accumulating model was constructed based on the hypothesis that the egg-laying capacity of geese was determined by two components of the photoperiod: photo-stimulation and photo-inhibition. In addition, a second segmented model was constructed based on the hypothesis that the photo-stimulation only occurred with lengthening photoperiods after the winter solstice, and the lesser laying rate in autumn could be attributed to the non-photo-dependent animal-husbandry technologies. This model consists of a logistic model before the winter solstice, and an accumulating model after this solstice. The use of the logistic and accumulating resulted in more precise predictions that occurred with use of Model 1 with a greater R2 and lesser RMSE, AIC and BIC. Likewise, the egg-laying curves when there was consideration of artificial photoperiods could also be constructed with consideration of stimulatory and inhibitory photoperiodic effects. The model consists of an initial logistic and subsequently a quadratic polynomial model. With use of this model, there is consideration of changes in egg-laying patterns when there is a fixed photoperiod, with the model parameters reflecting the effects by photoperiod control-programs and age of the geese. In conclusion, new mathematical models have been developed to best fit egg-laying curves when there are both natural and artificial photoperiods. These models can contribute to development of precision-feeding technologies for breeding geese in future.

Positive impact of moderate food restriction on reproductive success of the rainbow trout Oncorhynchus mykiss

Rainbow trout (Oncorhynchus mykiss) egg production is a key sector for aquaculture. This industry relies on well-controlled reproductive cycles and the extensive use of photoperiod control to obtain year-round egg production. However, feed management practices are very diverse among producers and not always designed to optimize egg production. Among these different practices, feed restriction is of major interest due to its direct impact on the reduction of egg production costs. It is however not always used under optimal conditions. The aim of the present study was to evaluate the impact of moderate feed restriction on reproductive performances and egg quality in rainbow trout. For that purpose, two feeding strategies were implemented during the last five months before the second reproduction. Females were either fed (1) ad libitum, or (2) 80% of ad libitum (i.e. restricted) with a commercial diet. An artificial photoperiod was applied to trigger reproduction during the summer. As expected, feed restriction resulted in smaller females in comparison to those fed ad libitum whereas gonado-somatic index was significantly higher in restricted females. In addition, hatching rate was significantly higher for eggs from originating from restricted females. Feed restriction led to the production of bigger eggs with less size variability and lower number of non-viable eggs. These restricted females also exhibited lower viscero-somatic index suggesting an impact of feed restriction on the allocation of reserves. However, lipid content in eggs and muscle were not different between groups, while fatty acid profile of eggs presented some differences. PUFA analysis revealed that proportions of ALA, AA and EPA were higher in eggs from restricted females, a feature possibly linked to higher egg quality. Together, these results demonstrate that feed intake of female rainbow trout broodstock can be reduced by at least 20% without any negative impact on egg production and egg quality.

Natural post-flowering photoperiod and photoperiod sensitivity: Roles in yield-determining processes in soybean

Promising yield-determining responses to artificial photoperiod manipulation during post-flowering phases have been identified in soybean [Glycine max (L.) Merrill]. These responses enhance resource capture as a result of changes in phase duration, and resource use efficiency as a result of changes in node production and pod development, alleviating intra-node pod interference. This work aims to evaluate the relevance of these responses under natural conditions and discriminate direct from indirect photoperiodic effects, that is, effects caused by changes in the capture of resources. Two field experiments were conducted with a combination of sowing dates, with similar pre- and different post-flowering photoperiod, indeterminate genotypes including near isogenic lines and commercial varieties with different photoperiod sensitivity, and shadings with different incident radiation during post-flowering. Longer post-flowering photoperiod and higher plant photoperiod sensitivity delayed crop development, particularly in lines with alleles E2, E3 or Clark background. This delay resulted in extra radiation capture and node production, which were positively related to yield. Direct photoperiodic effects on nodes per m2 were evidenced in response to changes in post-flowering photoperiod and plant photoperiod sensitivity. The distribution of available resources such as radiation in more nodes per m2 increased use efficiency. Longer post-flowering photoperiod and higher plant photoperiod sensitivity enhanced pod establishment on usually dominated positions such as lateral racemes, affecting pods per m2. Finding these relevant yield-determining effects under natural conditions suggests that processes related to post-flowering photoperiodic responses are a plausible way to enhance resource capture and use efficiency and yield in soybean production systems. In cropping systems in which the whole growing season is used to maximize yield, these post-flowering photoperiodic responses could be adopted at the expense of the pre-flowering phase duration.

Improvement of natural spawning of black flounder, Paralichthys orbignyanus (Valenciennes, 1839) by photothermal and salinity conditioning in recirculating aquaculture system

Black flounder (Paralichthys orbignyanus) is an important commercial and recreational species inhabiting marine and estuarine waters from Rio de Janeiro (Brazil) to San Matías Gulf (Argentina) from 1 to 30 m depth, with a great potential for aquaculture in coastal or internal brackish waters. It is an estuarine-dependent species whose adults reproduce in marine water during the spring and summer. Since 2003, the reproduction of flounder broodstock in a recirculating aquaculture system (RAS) subject to a photothermal period and constant salinity of 34 psu has been carried out at the National Institute for Fisheries Research and Development (INIDEP). Final maturation of broodfish was regularly achieved through the use of a photoperiod and water temperature regimen simulating natural seasonal changes over a 10-month period, reaching 19–20 °C and 16 h L:8 h D by February. These spawning events were unstable and unpredictable, with wide variations in quality and quantity of eggs. Control of the reproductive cycle and development of cultured broodstocks are basic requirements for a successful aquaculture industry. In order to acquire a more precise control of egg production, the effect of salinity variation upon the quantity and quality of spawning eggs of the flounder broodstock in a RAS during three reproductive seasons was evaluated. For that purpose, salinity was changed according to photoperiod and temperature variations along the year as: a) fall-winter, 16–12 °C, salinity 25–15 psu, natural photoperiod at low light intensity (10 lx), and b) spring-summer, 16–19 °C, salinity 15–34 psu, artificial photoperiod and mean light intensity (200 lx). The result of the present study indicated that the combination of photothermal and salinity regimes effectively extended reproductive activity in the broodstock tank and increased both the number of spawning events and the amount of eggs in relation to previous years. 2015–2016 and 2016–2017 reproductive seasons lasted for >150 days, reporting a total of 52 and 53 spawning events and reaching 14,289,661 and 17,593,888 eggs released, of which 37.8% and 32.5% were viable eggs, respectively. The 2017–2018 reproductive season lasted 106 days with 55 spawning events and 27,548,896 eggs released (61.0% viable eggs), reaching the greatest number of total eggs obtained in any season at INIDEP since 2003.

Artificial long-day photoperiod in the subtropics increases body weight in goat kids born in the autumn

To determine whether exposure to artificial long days increases the body weight of subtropical goat kids born in autumn, sixty-four goat kids were distributed in a completely randomized design with a factorial arrangement. Experimental groups consisted of two photoperiod treatments (natural or artificial photoperiod, 16 h light: 8 h darkness), and two suckling types (natural or artificial). The mean body weight, recorded at day 27 of age, was higher in goat kids subjected to artificial long days (7.7 ± 0.2 kg) than in those maintained under a natural photoperiod (7.0 ± 0.2 kg; P < 0.05). The mean daily gain was higher in light-treated kids (163 g/d) than in those maintained on a natural photoperiod (141 g/d; P < 0.001). Likewise, the mean blood glucose concentration was higher in goat kids submitted to artificial long days (102.0 ± 1.3 mg/dL) than in those kids maintained on the natural photoperiod (92.5 ± 1.3 mg/dL; P < 0.001). The suckling type had an effect on the plasma insulin-like growth factor-1 concentrations (IGF-1) of the kids (P < 0.01), and this effect was more pronounced in goat kids under artificial long days (P < 0.05). The results of the present study show that in subtropical goat kids born during the autumn, exposure to an artificial long-day photoperiod promotes a high body weight during the early phase of growth, independent of whether they are reared or not by their dams. In addition, these results also showed that, depending on suckling type, exposure to artificial long days increase the concentrations of IGF-1 in goat kids.

Melatonin concentrations in Chinese mitten crabs (Eriocheir sinesis) are affected by artificial photoperiods

ABSTRACTMelatonin is a ubiquitous and conservative biogenic amine implicated in a variety of bio-physiological processes. Although the daily variations of melatonin concentrations have been determined in many crustacean species, results have been conflicting. The present study was undertaken to evaluate the effect of different photoperiods on the circadian rhythms of melatonin in Eriocheir sinensis by using high performance liquid chromatography. The circadian rhythms of melatonin in the eyestalk of E. sinensis were influenced by external light stimulation. When under consistent light (24L:0D) and consistent dark (0L:24D), the melatonin rhythm in eyestalks and hemolymph was disturbed with respect to that of the control group (12L:12D). However, disturbance owing to different photoperiod treatments decreased with increasing treatment duration. Our results underscore the exquisite sensitivity of melatonin content to different photoperiods. These findings may have real-world implications in terms of the disruption of circadian rhythms induced by exposure to different photoperiods.

Sperm quality analysis of normal season (NG) and out-season by photoperiod manipulation (PG) of male rainbow trout broodstock (Oncorhynchus mykiss)

Sperm quality parameters in rainbow trout (Oncorhynchus mykiss) were investigated during normal season spawning (November-January) and out-season spawning (July-August) treated with artificial photoperiod manipulation. Normal spawning males (n = 15) were kept in an open concrete pond under natural condition. Out-season spawning males (n = 15) were treated with artificial LED light (50lm/m2) in a closed concrete pond. In these two experimental groups, five fish were used in each of three spawning periods. The mean weight and body length of males (2 + years, n = 30) were 1213.43 ± 39.43g and 45.08 ± 0.62cm, respectively. Sperms were collected from July to August 2016 in the out-season spawning or photoperiod-manipulated group (PG) (water temperature 14.21 ± 0.31°C) and from December 2016 to January 2017, in the normal season spawning group (NG) (water temperature 8.81 ± 1.03°C). Volume of sperm, osmolality of seminal plasma, density of sperm, percentage of motile spermatozoa (MOT), curvilinear velocity (VCL), and duration of motility were measured for each male. Seminal plasma osmolality, density of sperm, and the motility of duration were 358.47 ± 37.24 and 308.87 ± 44.09, 4.37 ± 2.10 and 9.8 ± 1.56, and 8.8 ± 2.42 and 24.6 ± 6.76 in PG and NG, respectively. Fertilization rate was 37.79 ± 9.37% and 94.51 ± 1.33% in PG and NG, respectively. Sperm quality parameters showed significant differences in most of the cases (p < 0.05) and fertilization rate at eyed egg stage (150-160 degree-days) was significantly higher in normal season spawning group than the photoperiod-manipulated group (p < 0.05). Though the rate of fertilization was low in out-season, it was able to get enough gametes in summer using only artificial light having no changes in other parameters.

Effect of Two Levels of Temperature and Natural and Artificial Photoperiod on Growth and Metamorphosis of Bullfrog Tadpoles in an Intensive Rearing System

AbstractThe effect of two levels of temperature and natural and artificial photoperiods on the growth and metamorphosis of tadpoles of the American bullfrog Rana catesbeiana were evaluated in an intensive‐rearing culture environment. Four groups of tadpoles at Gosner stage 24–25 were subjected for 50 d to four different treatments: (1) Tadpole culture with temperature control system (25.9 ± 0.34°C) and natural photoperiod of 12.25 h light : 11.75 h dark (treatment T), (2) an artificial photoperiod of 10 h light : 14 h dark using a white LED lamp and no temperature control system (18.7 ± 1°C) (treatment P), (3) the combination of temperature control system (26.01 ± 0.44°C) and an artificial photoperiod (10 h light : 14 h dark) (treatment T/P), and (4) culture with no temperature control system (21.87 ± 1.09°C) and a natural photoperiod (12.25 h light : 11.75 h dark) (treatment N/S). The experiment was performed under greenhouse conditions. Tadpoles in treatments T and T/P had the best growth performance as measured by total length (45.34 ± 1.89 mm [mean ± SE] for T/P, 44.72 ± 2.13 mm for T), head length (17.15 ± 0.67 mm for T/P, 18.34 ± 0.70 for T), and weight (1.00 ± 0.03 g for T/P, 1.14 ± 0.013 g for T). Tadpoles reared using white light LED lamps had reduced growth. The best results for tadpole metamorphosis were obtained in treatment T/P (25.9%), while treatment P presented the highest survival (36.2%). This experiment demonstrates that having temperature regulation is important to achieve better tadpole growth in intensive rearing systems. The regulation of both variables (T and P) is recommended for activating metamorphosis in the final phases of the tadpole development.

THE DETECTION OF THE TIME OF CONVERSION FROM VEGETATIVE TO REPRODUCTIVE GROWTH IN Swainsona formosa (FABACEAE)

The induction of chromosome doubling using antimitotic chemical will only be effective when the substance is applied at vegetative growth phase, as it works only during mitotic division within cells of actively growing tissues. Therefore, this investigation was carried out to determine the precise conversion time from vegetative into reproductive growth stage, that in turn can be used as a reliable reference for the application of antimitotic chemicals in doubling the chromosome number in Swainsona formosa. The conversion from vegetative to reproductive growth in Swainsona formosa was successfully determined with particular emphasis on the effect of different photoperiods. Although photoperiod affected the time required for first flower initiation, the number of nodes before the plant entering the reproductive stage was not affected by photoperiod and presumed to be set genetically. It was found that under artificial photoperiods of 16, 12 and 8 hours the 12th and 11th nodes were the critical nodes for the main and side stems, respectively. Meanwhile the 10th and 8th nodes were found to be critical for main and side stems of plants grown under natural photoperiods ranging from 12 to 16 hours during their life cycle. Histological examination indicated that when the plants were grown under 12 – 16 hours photoperiods the first floral bud formation was initiated within 56 – 60 days after germination, thus this period was considered as the critical time for the conversion from vegetative to reproductive growth in S. formosa.&#x0D; &#x0D; Keywords: Sturt’s desert pea, legume, ornamental plant, plant breeding.

Melatonin, cortisol and progesterone in alpine goat’s superstimulateds with FSH-OV and artificial photoperiod

Background It is already well known the importance of hormones such as progesterone cortisol and melatonin on the reproduction of females of various species However as regards the goat species there is still a lack of data especially in animals used in oocyte donation programs for subsequent in vitro production of embryos The objective of this study was to verify the profile of progesterone cortisol and melatonin during the hormonal treatment of ovarian stimulation in the anestrous transition and reproductive season in Alpine goats using artificial and natural photoperiod Seventeen female Alpine goats were reared at latitude deg S The animals were treated with mg oFSH Ovagen ICP New Zealand in decreasing doses for four consecutive days at the end of a progestin treatment with CIDR reg Intervet New Zealand at the reproductive season G n and anestrous with artificial photoperiod G n or natural G n Blood samples were taken before during and after the period of ovarian stimulation and during oocyte harvest by laparotomy Blood collection for melatonin was performed overnight for progesterone and cortisol were performed for days in the morning The values were presented as mean standard deviation and median for the groups and compared by non parametric analysis Kruskal Wallis analysis of variance and Friedman With regard to progesterone there was a difference P lt between the three groups studied and in the two periods reproductive season anestrous with higher values in the reproductive season Statistical differences P gt were not observed for cortisol between groups however after laparotomy there was a significant increase P lt in the operated goats G plusmn nmol L compared to those not operated at the reproductive season G plusmn nmol L and G plusmn nmol L Serum cortisol values were lower than those of the reproductive season for all groups G plusmn nmol L natural photoperiod non laparotomized goats G plusmn nmol L artificial photoperiod laparotomized goats and G plusmn nmol L natural photoperiod laparotomized goats However the surgical group G in artificial photoperiod presented serum cortisol levels between the non surgical group G in the natural photoperiod and the surgical group G in the natural photoperiod leading to the belief that melatonin might have interfered with the values Cortisol of these animals in anestrus During the experimental period melatonin values were always high in all groups in the anestrous period G pg mL G pg mL and G pg mL Conclusion Under the conditions of this study it is possible to verify an influence of the season reproductive or anestrous and possibly melatonin on the secretion of cortisol in these animals

Effect of growing media and fertilization on sugarcane flowering under artificial photoperiod.

The USDA-ARS Sugarcane Variety Development Program in Houma, LA aims to maximize the number of panicles available for crossing through artificial manipulation of the environment. In a three-year study, the effect of growing media, fertilizer treatment, and their interaction on sugarcane flowering (% of panicles emerged), and number of days to flowering (DTF) under an artificial photoperiod treatment were assessed. The commercially-available sugarcane cultivar, ‘HoCP 96–540’ was planted in 2.8-L pots and subjected to the standard local photoperiod treatment. The cultivar was planted in four growing media (RediEarth Seedling and Germination Mix, Fafard, Metro-Mix®902, and Metro-Mix®900) and subjected to three different fertilizer applications. In the control treatment, fertilizer application was stopped prior to the commencement of the photoperiod treatment as practiced in some sugarcane breeding programs. The continuous treatment consisted of an application of a 10 ml solution of a NPK three times a week between June and October. The partial treatment consisted of applications of the same NPK solution applied post-initiation between September and October. Nitrogen starvation prior to the commencement of the photoperiod treatment is generally accepted to improve flower initiation; thus the standard practice is to cease nitrogen application two weeks prior to beginning a photoperiod regime. The growing media used in this study did not have a significant effect on days to flowering or percent panicle emergence. In our study, the control fertilizer treatment showed a flowering percentage across all growing media types of 21.2% less than a continuous fertilization regime. Furthermore, a significant trend was observed between fertilization treatments and days to flowering, with the continuous treatment producing panicles, on average across growing media, four days earlier than the control treatment, and six days earlier than the partial treatment. Evidence across this three-year experiment indicates that we should consider modifying plant nutrition management as soil fertility was found to be inadequate.

Profile of gonadotropic hormone secretion in sheep with disturbed rhythm of seasonality

The effect of artificial conditions of a short daylight period (16 h darkness (D): 8 h light (L)) and exogenous melatonin on milk yield parameters of sheep during spring and summer was examined to determine the impact of using sheep for milk on the secretion level of gonadotrophic hormones. The research was conducted on 60 sheep lambed in February. After raising the lambs, the sheep were divided into 3 groups and assigned for dairy use (May–September). The mothers in the control Group 1 (G1) were maintained under natural daylight conditions. The sheep in Group 2 (G2) were maintained under conditions of an artificial photoperiod (16 h D : 8 h L). Meanwhile, the mothers in Group 3 (G3) were given melatonin implants. A 6-hour collection of blood from 6 sheep of each group was performed every 4 weeks. The concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in plasma were measured using radioimmunoassay. The average LH concentration in G1 gradually increased since May (5.32 ± 0.2 ng/ml), reaching the highest value in August (6.70 ± 0.2 ng/ml). In G2, the increase in LH occurred 4 weeks after the introduction of the 16 h D : 8 h L condition (6.26 ± 0.2 ng/ml). The maximum LH concentration in G3 was noted in August (7.31 ± 0.2 ng/ml). The average FSH concentration in G1 gradually increased since May (6.59 ± 0.2 ng/ml), reaching the highest value in August (10.50 ± 2.6 ng/ml). In G2, there was a significant increase in the FSH concentration in June (9.00 ± 0.3 ng/ml). In the final period during lactation, the FSH concentrations in G2 (13.51 ± 1.3 ng/ml) and G3 (13.60 ± 1.9 ng/ml) were higher than in G1. The results indicate that using sheep for milk does not inhibit the secretion of gonadotropic hormones induced by the simulation of short daylight conditions and exogenous melatonin.

Deep anestrous mares under natural photoperiod treated with recombinant equine FSH (reFSH) and LH (reLH) have fertile ovulations and become pregnant

The most common equine breeding practice to decrease the time to the first ovulation of the year is to use artificial lights starting December 1 in the Northern Hemisphere. It can take 60–90 d for this lighting regimen to induce a fertile ovulation. The success rate for pharmaceutical compounds to carry out the same process has been variable. One compound that did induce an early ovulation was recombinant equine follicle stimulating hormone (reFSH), but neither pregnancy nor cyclicity was established in that study. Starting on December 1, 20 deep-anestrous mares of light horse breeds (4–15 y old) with follicles ≤ 20 mm in diameter and progesterone < 1 ng/mL were maintained under natural photoperiod while 10 control mares were maintained under artificial photoperiod. Starting on February 6, treatment mares were randomly assigned to one of two groups: reFSH (n = 10) or reFSH/reLH (n = 10). Jugular blood samples were collected daily from all mares, and luteinizing hormone (LH), FSH, progesterone (P4), estradiol-17β (E2) and immunoreactive (ir)-inhibin were analyzed by radioimmunoassay (RIA). When the largest follicle reached ≥32 mm in diameter, reFSH treatment was discontinued in both groups while reLH treatment continued in the reFSH/reLH group until a cohort of follicles reached ≥35 mm in diameter. Human chorionic gonadotropin (hCG) was administered intravenously (iv) to induce ovulation, and mares were bred to a fertile stallion every other day until ovulation. Mares receiving either reFSH or reFSH/reLH developed follicles ≥35 mm within 5–6 d of treatment compared with 15.8 ± 3.4 d in the control group. Both reFSH and reFSH/reLH induced ovulation in 100% of the mares within 10 d after treatment resulting in an 80% conception rate and a 70% pregnancy rate for both groups. Conception and pregnancy were designated as either presence of a 14 d old embryo (n = 16) or a fetal heartbeat at 24 d (n = 14), respectively. Only three mares in the control group ovulated within the same treatment period. Later ovulations in the control group resulted in 100% conception and pregnancy rates. At 25 d post-conception, treated mares that were pregnant (n = 7 per group) were administered prostaglandin (PGF2α) to terminate the pregnancy and later returned to estrus. Treatment with reFSH or reFSH/reLH given to deep-anestrous mares under natural photoperiod induced fertile ovulations that resulted in pregnancy and cyclicity when pregnancies were terminated.

Effects of season and artificial photoperiod on semen and seminal plasma characteristics in bucks of two goat breeds maintained in a semen collection center.

Aim:This study quantified the effects of season and photoperiodic treatment on semen and seminal plasma (SP) characteristics in 12 bucks of two Spanish goat breeds (Murciano-Granadina, and Payoya) for the past 1 year.Materials and Methods:A total of 6 bucks (three of each breed) were exposed to the natural day length and the other six males (three of each breed) were exposed to alternating conditions of 2 months of long days (16 h light) and 2 months of short days (8 h light). Weekly concentrations of glutamic oxaloacetic transaminase/aspartate aminotransferase (GOT/AST), lactate dehydrogenase (LDH), potassium, testosterone, and protein in SP were measured. Reaction time and scrotal circumference were recorded, and plasma testosterone concentrations were measured before semen collection.Results:Sperm volume, LDH, and potassium concentration in SP, and reaction time did not differ significantly between breeds, seasons, and photoperiodic treatment. Sperm concentrations were higher (p<0.001) in spring and summer than they were in autumn and winter. Mean percentage of positive hypo-osmotic swelling test sperm was the highest in summer and under the artificial photoperiod (p<0.01). GOT/AST concentrations differed (p<0.01) between breeds and seasons. Breed, season, and photoperiod had significant (p<0.001) effects on protein and testosterone levels in SP. Plasma testosterone concentrations were highest in summer (p<0.001), and differed significantly (p<0.01) between breeds. Scrotal perimeter differed significantly (p<0.001) between breeds and photoperiod.Conclusion:Recognition of those seasonal and breed-specific differences in the performance of bucks should help to improve the management of individual semen samples for use in artificial insemination programs.

Extended day length in late winter/early spring, with a return to natural day length of shorter duration, increased plasma testosterone and sexual performance in rams with or without melatonin implants.

Sixteen rams were used to quantify the effects of long days, imposed during late winter/early spring, with or without exogenous melatonin, on plasma testosterone concentrations and ram serving capacity. Rams were assigned to two groups: photoperiod-treated rams (Artificial Photoperiod, AP; n=8), exposed to 2months of long days (16hr of light/day) between 22 December and 22 February, and control rams (Natural Photoperiod, NP; n=8). At the end of the long-day period, AP rams were returned to the natural photoperiod, and each ram in the two groups either did (+M) or did not (-M) receive three subcutaneous melatonin implants. Four groups were created as follows: AP+M (n=4), AP-M (n=4), NP+M (n=4) and NP-M (n=4). Thirty days after of the onset of photoperiodic treatment, AP rams (13.5±2.8ng/ml) had significantly (p<.05) lower testosterone levels than NP rams (36.7±1.0), and similar differences were not apparent at the end of the photoperiod treatment. A month later, AP rams (24.3±7.9) had higher (p<.10) testosterone levels than NP rams (13.1±5.0), with no effect of melatonin treatment. Fifty days after melatonin implantations, rams were exposed for 20min to three oestrous ewes. AP rams (2.50±0.42) exhibited significantly (p<.05) more serves than did NP rams (1.11±0.39), and melatonin treatment had no significant effect; however, the interaction between treatments was significant. Time to first serve was significantly (p<.05) shorter in AP (2.30±1.20min) than it was in NP rams (5.58±0.68min). In conclusion, exposure to 2months of long days in late winter/early spring, with a return to natural day length of shorter duration, increased plasma testosterone concentrations and sexual performance in rams with or without exogenous melatonin. This particular management is an option if a non-hormonal reproductive strategy is scheduled; yet, if the use of exogenous hormones is feasible, melatonin implants increase the mating efficiency of rams.

Induction of out-of-season egg laying by artificial photoperiod in Yangzhou geese and the associated endocrine and molecular regulation mechanisms

This study was carried out to induce out-of-season breeding, in the summer, and to achieve high reproductive performance using artificial photoperiod manipulation in the long-day breeding Yangzhou goose. Young geese were subject to a two-phase short-to-long (group A) or a three-phase (long-short-long; group B) photoperiod program February through October. Egg-laying was induced to start similarly in both groups in May, increased to a peak level in July, and then decreased gradually through to October. The peak and post-peak laying rates were higher with the three-phase than with the two-phase program. Plasma progesterone concentrations changed similarly in the two groups, increasing from low levels during the pre-lay periods until the peak laying stage, then decreasing with decline in the egg-laying rate. Plasma T3 concentrations increased from the beginning of the experiment to form the first peak under a short photoperiod, declined to a trough at peak lay and then progressively increased to high levels towards the end of the experiment. Plasma T4 concentrations increased throughout the experiment, showing little response to changes in photoperiod. GnIH mRNA expression level in the hypothalamus steadily decreased from high levels under the short photoperiod to a nadir at peak of lay, but was abruptly up-regulated by over a thousand-fold thereafter. This mRNA expression pattern was also shared by GnIHR, VIPR, TRHR, TSH, and PRL genes in the pituitary gland, and to lesser extent, by GnRH, VIP, and TRH genes in the hypothalamus. Pituitary GnRHR mRNA expression levels changed in a similar manner to that of reproductive activities of geese in both groups. FSH beta subunits mRNA expression levels increased to high levels after day 11 of the long photoperiod, and were higher in group B than in group A at peak laying. LH beta gene expression level was similarly upregulated by photoperiod and was higher in group B than in group A when used the multivariable and two-way analyses of variance. Taken together, photoperiod, through regulation of expression of an array of genes in the hypothalamus and pituitary gland, synchronized stimulation and refractoriness of the reproductive system in Yangzhou geese. The higher out-of-season egg laying performance following the three-phase photo-program treatment was mediated by higher FSH beta and LH beta subunit mRNA expression levels.

Dependence of nighttime sleep duration in one-month-old infants on alterations in natural and artificial photoperiod

Human sleep–wake cycles are entrained by both natural and artificial light–dark cycles. However, little is known regarding when and how the photoperiod changes entrain the biological clock after conception. To investigate the dependence of sleep patterns in young infants on the natural and artificial light–dark cycles, 1,302 pairs of one-month-old infants and their mothers were asked to answer a questionnaire. Birth in spring, longer daytime sleep duration, early/regular light-off times, and longer maternal nighttime sleep duration were identified as independent variables for longer infant nighttime sleep duration in both univariate and multivariate analyses. Longer maternal nighttime sleep duration was dependent on shorter naps and early/regular bed times but not on the season. We found that nighttime sleep duration depended on both natural and artificial diurnal photoperiod changes in one-month-old infants. Although sleep patterns of infants mimicked those of their mothers, nighttime sleep duration depended on the season, and was positively associated with daytime sleep duration, only in the infants. These specific variables, which render sleep patterns of the infants different from those of their mothers, might be a clue to reveal the covert acquisition process of mature circadian rhythms after birth.

Effect of different colours of light on growth performance of broilers

A study was carried out to quantify the effect of different wavelengths of light on the production performance of broilers. A total of 240, day-old straight run broiler chicks were divided into 4 treatments each comprising of four replicates of 15 birds each. Chicks pertaining to treatment group G1, G2, G3 and G4 were provided blue light, green light, red light and plain incandescent light respectively. All treatments were provided continuous artificial photoperiod of 24 hours up to the rearing period (6wks). Light proofing of pens was done by black curtains. At 6weeks of age the body weight of the G1 group was found significantly higher than other groups. Again significantly higher overall body weight gain was noticed in G1 group followed by G4, G3 and G2. Feed consumption was significantly higher in G1 followed by G3, G4 and G2. Feed conversion ratio was significantly higher in G3 and lower in G1 group. It is concluded that birds reared under the blue light showed highest body weight, body weight gain and feed consumption with comparatively lower FCR.