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Context. The use of progesterone vaginal implants in sheep is frequently associated with vaginitis and adherences; and can hamper fertility in estrus synchronization programs. Aims. The aim of this study was to characterize the plasma hormone profile induced by two injectable progesterone (iP4) formulations in ewes. Methods. In Experiment 1, ewes received 20 or 40 mg of an iP4, with a third group as a control. In Experiment 2, 75 or 150 mg of a long-acting iP4 were administered, again with a control group. Key results. In Experiment 1, progesterone concentrations remained at luteal levels for less than 24 h. The intervals from iP4 treatment to the onset of estrus and ovulation were greater treated than in control ewes (P < 0.01). The proportion of ewes that ovulated within 8 days after treatment was lower in ewes that received 40 mg iP4 than in control ewes (P < 0.05). In Experiment 2, mean progesterone concentrations remained at luteal levels for 120 h. The interval from iP4 administration to estrus was longer in 150 mg treated ewes than in control ewes (P < 0.01). The interval from treatment to ovulation was longer in ewes treated with 150 mg than 75 mg and control ewes < 0.05). The proportion of ewes that ovulated was lower at 150 mg (P < 0.05). Conclusions. The iP4 formula used in Experiment 1 could not maintain luteal levels for more than 24 h. The use of longacting iP4 maintained plasma progesterone concentrations above luteal levels for at least 5 days. The longacting treatment can therefore be tested for estrous synchronization treatments. Implications. The long-acting progesterone may be an alternative to short estrous synchronization protocols. [ABSTRACT FROM AUTHOR]

This study investigated the seasonal changes in embryonic development of the red snow crabs inhabiting the deep sea using wild and captive ovigerous females. The embryonic stages were categorised into 14 groups based on their external morphology. Females with recently spawned eggs (between stage 1 and early stage 3), those with the eggs at the midterm stage (mainly stages 7 and 8), and those with eggs just before hatching (stage 14) were observed simultaneously from January to March indicating a 2-year reproductive cycle. These findings aid in understanding and identifying the spawning years of the red snow crabs sampled from their natural habitats. [ABSTRACT FROM AUTHOR]

Reproduction is a fundamental biological process that is essential for the continuous survival of fish species. Understanding their early life history and reproductive biology can explain how the population behave over time. A total of 1,238 fish samples were examined to determine the reproductive patterns and period of fringescale sardinella (Sardinella fimbriata) from Malampaya Sound, Palawan, Philippines. Monthly sampling from April 2023 to March 2024 revealed a 1:1 sex ratio. Gonadal examination of the fish revealed the presence of spawning individuals throughout the study period. The minimum size of matured fish observed was 11.0 cm and 11.1 cm for male and female S. fimbriata, respectively. The peak of spawning was April as indicated by the highest calculated GSI of 7.62% and fecundity of 18,465. A smaller peak was again observed in the month of September. The length at maturity was estimated to be 11.4 and 8.8 cm for males and females, respectively. Fecundity ranged between 2,700 to 36,067 eggs per spawn for size class between 11.1-14.8 cm and weight 13.07-31.93 g. Regression analysis between fecundity and morphometric characteristics such as body length, weight, eviscerated weight, and gonad weight revealed a positive correlation. Very low coefficients of determination were computed, ranging between 0.0028-0.1233. A significant association between fecundity and the morphometric variable gonadal weight was observed, as shown by the p-value of 0.0000. These outcomes are valuable data in the formulation of conservation and management strategies for the area. Implementation of appropriate conservation measures, monitoring of environmental parameters, strict enforcement of fishery regulation, coupled with increased environmental awareness and community participation will guarantee the long-term sustainability of the fringescale sardinella population and the preservation and sustainable use of marine biodiversity in Malampaya Sound.

To understand the reproductive biology of Hemitripterus villosus in the Bohai Strait, and fill the key knowledge gap in verifying reproductive seasonality and documenting gonadotropin dependent reproductive cycle of this species, a year-round detail study was conducted for the first time. In total, 263 individuals were randomly sampled off the coasts of the Bohai Strait. Results show that and the overall female-to-male ratio (1.35:1) did not differ significantly from the 1:1 sex ratio. The length and weight relationship for females and males were regressed, depicting an isometric growth for both sexes. Four reproductive phases of the complete gonadotropin dependent reproductive cycle in both sexes were identified. The monthly variations in the gonadosomatic and hepatosomatic indexes for both sexes further indicated that this species spawns a single batch of eggs per year and the peak spawning period is from October to December. The average diameter of eggs ranged from 2.10 to 3.57 mm. The length at first sexual maturity was 224.87 mm for females and 241.26 mm for males. Significant positive relationships between absolute fecundity and fish size, and also gonadal weight were observed. H. villosus from the Bohai Strait exhibited smaller body size, smaller egg diameter, lower gonadosomatic index, lower absolute fecundity, and higher population extinction risk than the other populations' studied previously. Our findings contribute to understanding the status of this isolated westernmost population, and we emphasize that more efficient protection measures for the species and control measures are urgently required to improve the coastal environment in the Bohai Strait. [ABSTRACT FROM AUTHOR]

Simple Summary: This article focuses on the season effect on testicular morphometry and meat quality from outdoor-reared Bísaro pigs. Bísaro, an autochthonous Portuguese breed, is raised for long periods in outdoor pens after puberty and slaughtered around one year old for high-quality meat products. A total of 20 Bísaro boars, aged 13 months at the time of slaughter, were distributed into two groups according to the season at slaughter: Wi (winter) with 9 participants and Su (summer) with 11 participants. Surprisingly, while testicular volume in the Su group suggested lower functionality, boar taint compound analysis showed no significant differences. However, the panelists detected a more pronounced aroma and flavor of boar taint in the summer group. The meat quality traits presented no marked differences, although the fatty acid profile was higher in Wi than in Su. This study suggests the existence of reproductive seasonality in male Bísaro pigs, hinting at a dynamic variation of boar taint compounds throughout the year. Traditional outdoor pig farming is renowned for its emphasis on animal welfare and the production of highly valued, quality meat. While seasonality is known to impact certain animals, particularly those raised outdoors, there is a lack of research on Bísaro boars, a native Portuguese breed. This research study was conducted on a total of 20 male entire Bísaro pigs, reared in outdoor pens from 4 to 13 months old, and subsequently slaughtered. The animals were divided into two groups: one slaughtered in winter (Wi, n = 9), and the other in summer (Su, n = 11). The objective was to evaluate testicular morphometry, boar taint compounds, and meat quality traits, including sensory analysis and fatty acid profile. Testicles from the Su group exhibited reduced volume, indicating diminished functionality during that season. While no significant differences were observed in the boar taint compound analysis, panelists could discern a more intense aroma and flavor of boar taint in the Su meat. Other meat quality traits showed no significant variations, but the fatty acid profile displayed higher values in the Wi group. This study reveals that Bísaro boars experience reproductive seasonality, leading to variations in boar taint compounds across the seasons. This information is crucial for farm planning. [ABSTRACT FROM AUTHOR]

Sexually hyperactive bucks are more efficient than sexually hypoactive bucks in stimulating testosterone secretion and sexual behaviour in other bucks in seasonal sexual rest by the phenomenon that we called the “buck-to-buck effect”. Here, we determined whether physical separation and reduction of the duration of contact with the sexually hyperactive bucks would modify those parameters in sexually hypoactive bucks exposed to the “buck-to-buck effect”. Bucks were subjected to natural day length throughout the study; this was the sexually hypoactive group. Other bucks were subjected to artificial long days (16 h of light per day) from 15 November to 15 January followed by exposure to natural day length to stimulate their sexual activity during the rest season; this was the sexually hyperactive group. In Experiment 1, we determined testosterone concentrations and sexual behaviour of six sexually hypoactive bucks separated 1.5 m from six sexually hyperactive bucks for 60 days by a metal open work fence, while a control group of six sexually hypoactive bucks was in permanent contact with six sexually hyperactive bucks. In Experiment 2, the duration of contact with sexually hyperactive males was reduced from 31 days (contact group, six bucks) to 10 days (withdraw group, seven bucks). In experiments 1 and 2, there was an effect of time (P

In species with asynchronous reproductive cycles, where gamete production is not aligned with the mating season, either males or females must store sperm. This reproductive tactic is an obligatory feature of male rattlesnakes’ reproductive cycle due to asynchrony between spermatogenesis and mating. Given that the ductus deferens is the primary site of sperm storage in male snakes, we aimed to investigate the morphological and histochemical changes in the distal ductus deferens of C. durissus throughout its reproductive cycle. In this species, spermatogenesis begins in spring and peaks in summer, while testes regress during autumn and winter. The distal ductus deferens of 28 mature male specimens was evaluated using histomorphometric and histochemical methods. Spermatozoa were consistently observed within the lumen of the ductus deferens in almost all specimens. The principal cells of the distal region of ductus deferens reacted positively for Periodic Acid-Schiff and Bromophenol Blue. Secretions were observed in the apical region of the principal cells' cytoplasm and along the epithelium edge, which may be related to gamete maintenance. Increased secretory activity of the principal cells was observed during periods of testicular activity. A reduction in the lumen of ductus deferens occurs during testicular regression, indicating possible fluid resorption by epithelial cells. Fluid resorption might be one of the mechanisms to ensure stored sperm viability, as it provides an increase in the glycoprotein’s concentration.

We estimated the population density and investigated the social organization of sambar (Rusa unicolor unicolor) in Horton Plains National Park (HPNP), Sri Lanka. Distance sampling was conducted along six strip transects every month for a period over 3 years (2018–2020) to estimate the density of the sambar population in grasslands of HPNP (9.4 km2), while the antler stage of males and the behavior of individuals were recorded to describe the population's reproductive stage and hence the social organization. Population density estimates showed relative stability over the 3 years and varied over the seasons but with consistent peaks from year to year with the highest population densities recorded in November–December (212.93 ± 25.38 animals/km2 in 2018, 187.91 ± 28.51 in 2019, and 179.76 ± 31.85 in 2020). The highest percentage of males in hard antlers was observed from November through January, while the percentage of antlers cast sambar peaked from March to April each year. Hinds were observed with newborn calves throughout the year, but the highest number of newborn calves were recorded from July to August each year, while the number of calves counted each year varied from 210 to 267 individuals. The mean group size was variable throughout each year with the largest groups recorded from September to December (up to 52), the period accompanied by the most observations of mating and sparring behavior. Although on a tropical island, HPNP is situated on a rolling plateau landscape in the highlands, where sambar showed a degree of reproductive seasonality somewhat similar to temperate cervid species. [ABSTRACT FROM AUTHOR]

The study evaluated the reproductive performance of Ile de France, Texel, Suffolk and crossbred ewes in different seasons, considering season of mating, age, body condition score and breed. The herd was located at geographic coordinates −25.66114429 S, −49.27262198 W, in Fazenda Rio Grande, Paraná State, southern Brazil, in a semi‐intensive system. 643 mating were evaluated, under natural oestrous conditions in 10 consecutive breeding seasons (2015–2019), under a body condition score between 2.5 and 3.5 in 93.9%. Data were analysed using Chi‐square tests, binary logistic regression, ANOVA and t‐test. Considering the breeds and crossbred animals, a pregnancy rate (PR) of 83% (winter), 91% (autumn) and 89% (summer) with no differences between them was obtained, except for 77% PR in spring (p <.05). Ile de France and crossbred ewes showed similar PR in all four seasons. Suffolk ewes showed similar fertility rates in summer, autumn and winter, but reduced in spring (p <.05); Texel ewes showed lower PR in summer and spring compared to autumn and winter (p <.05). The twin PR (TPR) in autumn, winter and spring showed no differences, except for summer (p <.05). Age did not influence the PR of ewes <2 years, 2–8 years and >8 years in the seasons, except in summer. It was concluded that the reproduction of European ewes breeds under medium latitude, combined with the use of constant management and feeding conditions, resulted in a fertility rate above 77% in all seasons, resulting in constant production of lambs. [ABSTRACT FROM AUTHOR]

Although island endemic bats are a source of considerable conservation concerns, their biology remains poorly known. Here, we studied the phenology and roosting behavior of a tropical island endemic species: the Reunion free‐tailed bat (Mormopterus francoismoutoui). This widespread and abundant species occupies various natural and anthropogenic environments such as caves and buildings. We set up fine‐scale monitoring of 19 roosts over 27 months in Reunion Island and analyzed roost size and composition, sexual and age‐associated segregation of individuals, as well as the reproductive phenology and body condition of individuals. Based on extensive data collected from 6721 individuals, we revealed a highly dynamic roosting behavior, with marked seasonal sex‐ratio variation, linked to distinct patterns of sexual aggregation among roosts. Despite the widespread presence of pregnant females all over the island, parturition was localized in a few roosts, and flying juveniles dispersed rapidly toward all studied roosts. Our data also suggested a 7‐month delay between mating and pregnancy, highlighting a likely long interruption of the reproductive cycle in this tropical bat. Altogether, our results suggest a complex social organization in the Reunion free‐tailed bat, with important sex‐specific seasonal and spatial movements, including the possibility of altitudinal migration. Bat tracking and genetic studies would provide additional insights into the behavioral strategies that shape the biology of this enigmatic bat species. The fine‐scale spatiotemporal data revealed by our study will serve to the delineation of effective conservation plans, especially in the context of growing urbanization and agriculture expansion in Reunion Island. [ABSTRACT FROM AUTHOR]

Animal reproductive phenology varies from strongly seasonal to nonseasonal, sometimes among closely related or sympatric species. While the extent of reproductive seasonality is often attributed to environmental seasonality, this fails to explain many cases of nonseasonal breeding in seasonal environments. We investigated the evolutionary determinants of nonseasonal breeding in a wild primate, the chacma baboon (Papio ursinus), living in a seasonal environment with high climatic unpredictability. We tested three hypotheses proposing that nonseasonal breeding has evolved in response to (1) climatic unpredictability, (2) reproductive competition between females favoring birth asynchrony, and (3) individual, rank-dependent variations in optimal reproductive timing. We found strong support for an effect of reproductive asynchrony modulated by rank: (i) birth synchrony is costly to subordinate females, lengthening their interbirth intervals; (ii) females alter their reproductive timings (fertility periods and conceptions) in relation to previous conceptions in the group; and (iii) the reported effect of birth synchrony on interbirth intervals weakens the intensity of reproductive seasonality at the population level. This study emphasizes the importance of sociality in mediating the evolution of reproductive phenology in group-living organisms, a result of broad significance for understanding key demographic parameters driving population responses to increasing climatic fluctuations. [ABSTRACT FROM AUTHOR]

The objective was to evaluate fertility, cyclicality behavior, and sexual performance of Pantaneiro sheep throughout the year's photoperiods in Mato Grosso do Sul - Brazil. Two experiments were conducted. In experiment one, the ewes used aged between 2 and 4 years, distributed in three homogeneous groups of 54 animals and subjected to reproductive evaluation in three different predefined luminosity periods, consisting of autumn (11h 45 min.), spring (12h 30 min.), and summer (12h 55 min.). The characteristics studied were body weight (BW), body condition score (BCC), estrus distribution (EST), percentage of pregnant females per cycle (%P), plasma progesterone (PP), and fertility (F) in the three predefined seasons. The mating system used was controlled natural nocturnal and lasted for 45 days. Experiment two, evaluated the ram sexual activity. The males (10) were individually exposed to four ovariectomized ewes. The ewes cycled during evaluated seasons, and the highest fertility was observed in animals with BCC >2.75. The PP concentration differed among periods, and higher conception rates (F) were observed in autumn and spring. The rams (75%) had a medium of sexual performance when they performed more than two ejaculations in 20 min throughout the seasons. Pantaneiro sheep of both genders had a similar fertility index, with early and constant activity throughout the year, displaying no photoperiodism or seasonality. [ABSTRACT FROM AUTHOR]

Traditional outdoor pig farming is renowned for its emphasis on animal welfare and the production of highly valued, quality meat. While seasonality is known to impact certain animals, particularly those raised outdoors, there is a lack of research on Bísaro boars, a native Portuguese breed. This research study was conducted on a total of 20 male entire Bísaro pigs, reared in outdoor pens from 4 to 13 months old, and subsequently slaughtered. The animals were divided into two groups: one slaughtered in winter (Wi, n = 9), and the other in summer (Su, n = 11). The objective was to evaluate testicular morphometry, boar taint compounds, and meat quality traits, including sensory analysis and fatty acid profile. Testicles from the Su group exhibited reduced volume, indicating diminished functionality during that season. While no significant differences were observed in the boar taint compound analysis, panelists could discern a more intense aroma and flavor of boar taint in the Su meat. Other meat quality traits showed no significant variations, but the fatty acid profile displayed higher values in the Wi group. This study reveals that Bísaro boars experience reproductive seasonality, leading to variations in boar taint compounds across the seasons. This information is crucial for farm planning.

Abstract Although island endemic bats are a source of considerable conservation concerns, their biology remains poorly known. Here, we studied the phenology and roosting behavior of a tropical island endemic species: the Reunion free‐tailed bat (Mormopterus francoismoutoui). This widespread and abundant species occupies various natural and anthropogenic environments such as caves and buildings. We set up fine‐scale monitoring of 19 roosts over 27 months in Reunion Island and analyzed roost size and composition, sexual and age‐associated segregation of individuals, as well as the reproductive phenology and body condition of individuals. Based on extensive data collected from 6721 individuals, we revealed a highly dynamic roosting behavior, with marked seasonal sex‐ratio variation, linked to distinct patterns of sexual aggregation among roosts. Despite the widespread presence of pregnant females all over the island, parturition was localized in a few roosts, and flying juveniles dispersed rapidly toward all studied roosts. Our data also suggested a 7‐month delay between mating and pregnancy, highlighting a likely long interruption of the reproductive cycle in this tropical bat. Altogether, our results suggest a complex social organization in the Reunion free‐tailed bat, with important sex‐specific seasonal and spatial movements, including the possibility of altitudinal migration. Bat tracking and genetic studies would provide additional insights into the behavioral strategies that shape the biology of this enigmatic bat species. The fine‐scale spatiotemporal data revealed by our study will serve to the delineation of effective conservation plans, especially in the context of growing urbanization and agriculture expansion in Reunion Island.

Background. Anestrous goats can cycle and become pregnant after the introduction of sexually active bucks, but some of them become anestrus probably because they have been fertilized and early embryonic death occurred or because they have not been fertilized and become refractory to the stimulation of bucks. Objective. Determine whether goats that were mated by bucks become anestrus probably because of an early embryonic death or refractoriness to buck stimulation. Methodology. Vasectomized (n = 2) and intact (n = 2) bucks were rendered sexually active by exposure to artificially long days (16 h of light per day) followed by natural variations of photoperiod. Bucks were introduced into two groups of anestrous goats (n = 15 each) and remained with them for 53 days. Estrous behavior, ovulation and pregnancy rate were determined. Results. All goats came into estrus, ovulated and were mated by bucks at least once during the study. The proportions of females that displayed estrus with or without ovulation did not differ between the two groups within 9 days after the introduction of bucks. However, the proportion of goats that came into estrus with or without ovulation was greater in goats mated by vasectomized bucks from 20 to 28 and from 50 to 53 days after introducing the bucks (P < 0.05). Finally, the proportion of goats that ovulated after the introduction of the bucks, but later returned to anestrus did not differ in goats mated by vasectomized or intact bucks (14% vs 33%; P > 0.05). Implications. These results indicate that in nonpregnant goats, refractoriness to the continuous presence of the same bucks may explain at least in part, the return to anestrus of most goats that stop cycling after an initial sexual response to the introduction of bucks. Conclusion. Nonpregnant goats mated by sexually active bucks become in anestrus, probably because they become refractory to the presence of the same males.

The giant anteater (superorder Xenarthra) is listed as Vulnerable by the International Union for Conservation of Nature (IUCN) and a low reproductive rate is considered one of the factors contributing to population decline of the species. Nevertheless, little is known on reproductive features in male giant anteaters and, in this regard, microscopic testis morphology and spermatogenesis were studied in roadkill specimens in Brazil. Characteristics of germ cell populations resembled descriptions in other eutherian mammals including other xenarthran species. Furthermore, eight stages of the seminiferous epithelium cycle could be defined. The proposed staging system offers baseline data for assessing impairments or seasonal changes in spermatogenesis and thus allows future studies on reproductive health and reproductive seasonality in male giant anteaters.

Context: In subtropical latitudes, most goats are managed in semi-extensive management systems, eating only available vegetation. Underfeeding is common during the dry season and may reduce the endocrine and sexual activities of male goats. Aims: The aim of the study was to determine plasma testosterone concentrations, sexual behaviour and sperm production of male goats kept in a semi-extensive management system for 12 months, from March to February. Methods: Control males were placed indoors and were well nourished (n = 5). Experimental males were placed in a flock and grazed daily with females for 7 h, eating only natural vegetation (n = 5). Experimental males were fitted with an apron to prevent mating during the study. Plasma testosterone concentrations were determined every 2 weeks. Sexual behaviour and sperm production were determined in May and June (beginning of breeding season), August and October (middle of season), and November and December (end of season). Key results: Plasma testosterone concentrations were higher (P < 0.05) in control than experimental males in June and from August to December. The percentage of males refusing to ejaculate was lower (P < 0.05) in control than experimental males throughout the study. Total number of spermatozoa per ejaculate was higher (P < 0.05) in control than experimental males in May, June, November and December. Sperm progressive motility was higher (P < 0.05) in control than experimental males in May and June and from October to December. Conclusions: The results indicate that male goats in a semi-extensive management system have lower plasma testosterone concentrations, sexual behaviour, and sperm quantitative and qualitative production than those in a confined management system. Implications: Nutritional supplementation may improve the endocrine and sexual activity of male goats in semi-extensive management systems. During the dry season (early autumn-late spring) in subtropical semi-extensive management systems, food availability decreases markedly, leading to undernutrition of male goats. We demonstrate that this undernutrition reduces sexual behaviour and sperm production during the breeding season (early summer–late autumn). This study indicates that nutritional supplementation may improve the sexual activity of male goats kept under semi-extensive management. [ABSTRACT FROM AUTHOR]

The study aimed to evaluate the effectiveness of combining two injectable progesterone (iP4) formulas for estrous synchronization in ewes and to compare it with traditional intravaginal progesterone devices. Additionally, the study assessed whether the inclusion of GnRH enhances the reproductive outcomes of the iP4 treatment. Two experiments were conducted. In the first experiment, 20 Santa Inês ewes were divided into two groups: one group received intravaginal progesterone devices, and the other received combined long-acting and short-acting iP4. In the second experiment, 30 Corriedale ewes were divided into two groups: one received the combined iP4 with GnRH, and the other without GnRH. Estrous, ovulation, follicular populations, and progesterone concentrations were monitored. The combined iP4 treatment induced an artificial luteal phase and produced reproductive responses similar to those obtained with intravaginal devices. In the first experiment, the iP4 treatment tended to result in more synchronized ovulation compared to the control (P=0.095). In the second experiment, adding GnRH enhanced the quality of the corpus luteum, as indicated by increased diameter and vascularization on Day 23 (P=0.047 and P=0.02, respectively). The combined administration of long-acting and short-acting iP4 effectively synchronized estrous in ewes and showed similar efficacy to traditional intravaginal devices. The inclusion of GnRH improved luteal quality, suggesting potential benefits for reproductive management in ewes. Further studies are needed to evaluate the fertility outcomes of these protocols under field conditions., Competing Interests: Conflicts of interest: The authors have no conflict of interest to declare., (Copyright © The Author(s).)

Abstract Background Carp fish, rohu (Labeo rohita Ham.) is important freshwater aquaculture species of South-East Asia having seasonal reproductive rhythm. There is no holistic study at transcriptome level revealing key candidate genes involved in such circannual rhythm regulated by biological clock genes (BCGs). Seasonality manifestation has two contrasting phases of reproduction, i.e., post-spawning resting and initiation of gonadal activity appropriate for revealing the associated candidate genes. It can be deciphered by RNA sequencing of tissues involved in BPGL (Brain-Pituitary-Gonad-Liver) axis controlling seasonality. How far such BCGs of this fish are evolutionarily conserved across different phyla is unknown. Such study can be of further use to enhance fish productivity as seasonality restricts seed production beyond monsoon season. Result A total of ~ 150 Gb of transcriptomic data of four tissues viz., BPGL were generated using Illumina TruSeq. De-novo assembled BPGL tissues revealed 75,554 differentially expressed transcripts, 115,534 SSRs, 65,584 SNPs, 514 pathways, 5379 transcription factors, 187 mature miRNA which regulates candidate genes represented by 1576 differentially expressed transcripts are available in the form of web-genomic resources. Findings were validated by qPCR. This is the first report in carp fish having 32 BCGs, found widely conserved in fish, amphibian, reptile, birds, prototheria, marsupials and placental mammals. This is due to universal mechanism of rhythmicity in response to environment and earth rotation having adaptive and reproductive significance. Conclusion This study elucidates evolutionary conserved mechanism of photo-periodism sensing, neuroendocrine secretion, metabolism and yolk synthesis in liver, gonadal maturation, muscular growth with sensory and auditory perception in this fish. Study reveals fish as a good model for research on biological clock besides its relevance in reproductive efficiency enhancement.

Most organisms reproduce seasonally, including most species of marine invertebrates that live across wide ranges in habitat, depth and environmental conditions. We asked: What ultimately selects for seasonal reproduction in benthic marine invertebrates with planktotrophic larvae (characteristic of ≥70% of marine invertebrates)? We hypothesized that seasonal variation in food available for the larvae ultimately selects for timing of adult reproduction. Testing this hypothesis requires a whole life cycle perspective and approach. Using a known proximate cue, daylength, we shifted gametogenesis in the laboratory by six months in a seasonally breeding temperate sea star, the Ochre Star Pisaster ochraceus (Brandt 1835). We were then able to induce spawning, fertilize gametes and culture resulting embryos in vitro to produce feeding larvae six months out of phase with natural photoperiod. We field‐reared these out‐of‐season larvae, similarly produced in‐season conspecifics and similar larvae of an aseasonally breeding asteroid, the Bat Star Patiria miniata (Brandt 1835) in mesh‐covered flow‐through containers that were deployed in seasonally contrasting oceanographic conditions reflecting different productivity regimes and larval food availability in spring and fall. Larval development and survival were similar between seasons: for example, planktonic larval duration was 48 d to first metamorphosis in spring vs. 45 d in fall for P. ochraceus. Hence, temporal variation in available phytoplankton may not be an ultimate selection factor acting on these larvae to regulate timing of seasonal reproduction in the adults. Alternatively, in this and other species of marine invertebrates, selection acting on early benthic juveniles or other life stages may determine the timing of adult reproduction. [ABSTRACT FROM AUTHOR]

The reproductive biology of Lutjanus vitta from the West Sulu Sea, Philippines was investigated by monthly sampling from October 2012 to December 2013. The reproductive activity was assessed to: characterize the sex ratio, determine the spawning period, estimate length and age at maturity (L50, A50) and determine the batch fecundity (BF). The overall sex ratio differed significantly (p

Reproductive seasonality is the norm in mammals from temperate regions but less common at lower latitudes, where a broad diversity of reproductive phenology strategies is observed. Our knowledge of the evolutionary determinants shaping this diversity remains fragmentary and may reflect high phenotypic plasticity in individual strategies. Here we investigated the ecological determinants and fitness consequences of variation in birth timing across the annual cycle in a social primate endemic to the Congo basin, the mandrill, Mandrillus sphinx , which breeds seasonally. We further examined traits that modulate this variation within and across individuals. We used 9 years of ecological, life history and behavioural data from a natural population to characterize patterns of environmental and reproductive seasonality. We then investigated the consequences of variation in birth timing for pre- and postnatal offspring survival and maternal interbirth intervals. Finally, we studied the influence of within- (reproductive history and age) and between-individual (social rank) traits on variation in birth timing. We found that mandrills' daily foraging time varied seasonally, with greater fluctuations for subordinate than dominant females. Birth timing was plastic, as females gave birth year round without detectable consequences for postnatal offspring survival. Giving birth within the birth peak, however, decreased interbirth intervals and probability of miscarriage. Finally, reproductive history and social rank mediated within- and between-individual variation in birth timing, respectively. Specifically, females that experienced a previous reproductive failure gave birth early in the next birthing season and dominant females bred less seasonally than subordinates, which may reflect their more even access to resources across the year. Overall, the selective pressures shaping mandrill reproductive seasonality differed from a classical scenario of seasonal fluctuations in resources limiting offspring survival. A complex interplay between social and ecological factors may thus determine within- and between-individual variation in phenology strategies of tropical and gregarious mammals. • Mandrills breed seasonally in an equatorial environment. • Dominant females breed less seasonally than subordinate ones. • Interbirth intervals are minimized when giving birth inside the birth peak. • Offspring survival is not affected by birth seasonality. • Miscarriage probabilities increase when conceiving late in the mating season. [ABSTRACT FROM AUTHOR]

Background: Carp fish, rohu (Labeo rohita Ham.) is important freshwater aquaculture species of South-East Asia having seasonal reproductive rhythm. There is no holistic study at transcriptome level revealing key candidate genes involved in such circannual rhythm regulated by biological clock genes (BCGs). Seasonality manifestation has two contrasting phases of reproduction, i.e., post-spawning resting and initiation of gonadal activity appropriate for revealing the associated candidate genes. It can be deciphered by RNA sequencing of tissues involved in BPGL (Brain-Pituitary-Gonad-Liver) axis controlling seasonality. How far such BCGs of this fish are evolutionarily conserved across different phyla is unknown. Such study can be of further use to enhance fish productivity as seasonality restricts seed production beyond monsoon season. Result: A total of ~ 150 Gb of transcriptomic data of four tissues viz., BPGL were generated using Illumina TruSeq. De-novo assembled BPGL tissues revealed 75,554 differentially expressed transcripts, 115,534 SSRs, 65,584 SNPs, 514 pathways, 5379 transcription factors, 187 mature miRNA which regulates candidate genes represented by 1576 differentially expressed transcripts are available in the form of web-genomic resources. Findings were validated by qPCR. This is the first report in carp fish having 32 BCGs, found widely conserved in fish, amphibian, reptile, birds, prototheria, marsupials and placental mammals. This is due to universal mechanism of rhythmicity in response to environment and earth rotation having adaptive and reproductive significance. Conclusion: This study elucidates evolutionary conserved mechanism of photo-periodism sensing, neuroendocrine secretion, metabolism and yolk synthesis in liver, gonadal maturation, muscular growth with sensory and auditory perception in this fish. Study reveals fish as a good model for research on biological clock besides its relevance in reproductive efficiency enhancement. [ABSTRACT FROM AUTHOR]

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• Sexually hyperactive bucks stimulate testosterone in males in sexual rest. • Sexually hyperactive bucks also stimulate sexual behaviour in males in sexual rest. • Stimulation occurs in permanent contact with sexually hyperactive bucks. • Separation from hyperactive bucks decreases testosterone and sexual behaviour. • Reduced duration of contact with hyperactive bucks decreases both variables. Sexually hyperactive bucks are more efficient than sexually hypoactive bucks in stimulating testosterone secretion and sexual behaviour in other bucks in seasonal sexual rest by the phenomenon that we called the "buck-to-buck effect". Here, we determined whether physical separation and reduction of the duration of contact with the sexually hyperactive bucks would modify those parameters in sexually hypoactive bucks exposed to the "buck-to-buck effect". Bucks were subjected to natural day length throughout the study; this was the sexually hypoactive group. Other bucks were subjected to artificial long days (16 h of light per day) from 15 November to 15 January followed by exposure to natural day length to stimulate their sexual activity during the rest season; this was the sexually hyperactive group. In Experiment 1, we determined testosterone concentrations and sexual behaviour of six sexually hypoactive bucks separated 1.5 m from six sexually hyperactive bucks for 60 days by a metal open work fence, while a control group of six sexually hypoactive bucks was in permanent contact with six sexually hyperactive bucks. In Experiment 2, the duration of contact with sexually hyperactive males was reduced from 31 days (contact group, six bucks) to 10 days (withdraw group, seven bucks). In experiments 1 and 2, there was an effect of time (P < 0.01) and an interaction between time and groups (P < 0.05). In Experiment 1, testosterone plasma concentrations were greater in bucks in contact with sexually hyperactive bucks than in those separated from bucks at 20 and 30 days after the introduction of sexually hyperactive bucks (P < 0.01). The bucks from the contact group also displayed more nudging than bucks from the separated group from 0 to 30 days (P < 0.001). In Experiment 2, testosterone concentrations were greater in the contact group than in those from the withdraw group from 19 to 31 days after the introduction of sexually hyperactive bucks (P < 0.05). Bucks from the withdraw group displayed more nudging than the contact group 7 days after the introduction of the sexually hyperactive bucks (P < 0.05). Afterwards, bucks from the contact group displayed more nudging than the withdraw group 14, 21 and 28 days after the introduction of the sexually hyperactive bucks. We concluded that physical separation and reduction of the duration of contact with the sexually hyperactive bucks decrease testosterone concentrations and sexual behaviour of bucks in sexual rest exposed to the "buck-to-buck effect". [ABSTRACT FROM AUTHOR]

Abstract Species following a fast life history are expected to express fitness costs mainly as increased mortality, while slow‐lived species should suffer fertility costs. Because observational studies have limited power to disentangle intrinsic and extrinsic factors influencing senescence, we manipulated reproductive effort experimentally in the cavy (Cavia aperea) which produces extremely precocial young. We created two experimental groups: One was allowed continuous reproduction (CR) and the other intermittent reproduction (IR) by removing males at regular intervals. We predicted that the CR females should senesce (and die) earlier and produce either fewer and/or smaller, slower growing offspring per litter than those of the IR group. CR females had 16% more litters during three years than IR females. CR females increased mass and body condition more steeply and both remained higher until the experiment ended. Female survival showed no group difference. Reproductive senescence in litter size, litter mass, and reproductive effort (litter mass/maternal mass) began after about 600 days and was slightly stronger in CR than IR females. Litter size, litter mass, and offspring survival declined with maternal age and were influenced by seasonality. IR females decreased reproductive effort less during cold seasons and only at higher age than CR females. Nevertheless, offspring winter mortality was higher in IR females. Our results show small costs of reproduction despite high reproductive effort, suggesting that under ad libitum food conditions costs depend largely on internal regulation of allocation decisions.

The beginning of husbandry in the Iberian Peninsula has been documented from the second half of the 6th millennium BCE and was based on the breeding of domestic caprines, mainly sheep. The first evidence of these practices comes from the Mediterranean region, but they quickly expanded inland. Previous studies have reported on the importance of the El Mirador sheepfold cave (Sierra de Atapuerca, Burgos, Spain) for understanding the process of the adoption of a farming economy in this inland region. In this study, we focus on husbandry and sheep management occurring in the 6th and 5th millennium cal BCE occupations of El Mirador cave by means of sequential oxygen (δ18O) and carbon (δ13C) isotope analyses in sheep molar tooth enamel. The results show a rapid adaptation and adoption of domestic sheep in the inland of the Iberian Peninsula. In El Mirador cave, well-organised sheep breeding was developed based on the concentration of births at the end of winter and early spring, for a period of ~2.64 months, which made husbandry more compatible with other economic activities. In 5th millennium levels, autumn births were also documented and may be indicative of the intervention of the shepherd in the reproductive cycle of the sheep and of a progressive adaptation of these animals to the interior of the Peninsula. All these strategies may have been supported by the recurrent occupations of the sheepfold, flocks grazing in the areas surrounding the cave and the possible use of leaf fodder in winter. [ABSTRACT FROM AUTHOR]

The evolutionary benefits of reproductive seasonality are often measured by a single-fitness component, namely offspring survival. Yet different fitness components may be maximized by different birth timings. This may generate fitness trade-offs that could be critical to understanding variation in reproductive timing across individuals, populations and species. Here, we use long-term demographic and behavioural data from wild chacma baboons (Papio ursinus) living in a seasonal environment to test the adaptive significance of seasonal variation in birth frequencies. We identify two distinct optimal birth timings in the annual cycle, located four-month apart, which maximize offspring survival or minimize maternal interbirth intervals (IBIs), by respectively matching the annual food peak with late or early weaning. Observed births are the most frequent between these optima, supporting an adaptive trade-off between current and future reproduction. Furthermore, infants born closer to the optimal timing favouring maternal IBIs (instead of offspring survival) throw more tantrums, a typical manifestation of mother–offspring conflict. Maternal trade-offs over birth timing, which extend into mother–offspring conflict after birth, may commonly occur in long-lived species where development from birth to independence spans multiple seasons. Our findings therefore open new avenues to understanding the evolution of breeding phenology in long-lived animals, including humans. [ABSTRACT FROM AUTHOR]

The reproductive biology of Lutjanus vitta from the West Sulu Sea, Philippines was investigated by monthly sampling from October 2012 to December 2013. The reproductive activity was assessed to: characterize the sex ratio, determine the spawning period, estimate length and age at maturity (L 50, A 50) and determine the batch fecundity (BF). The overall sex ratio differed significantly (p < 0.05) among size classes and months with male and female dominance, respectively. As expected for tropical fish, spawning occurred year-round with two main spawning periods (April and October). The highest gonado-somatic index (GSI) values were recorded with two peaks for females in April (2.53%) and October (2.48%), which correspond to the two main spawning periods and one peak for males in April (1.55%). Males reached the length and age at sexual maturity (L 50 = 22.8 cm, A 50 = 2.19 yrs.) and females (L 50 = 21.3 cm, A 50 = 1.76 yrs) indicating that sexual maturation differed by age and size across sexes. Fecundity increased exponentially with fish length and weight demonstrating a non-linear relationship between fecundity and fish size. [ABSTRACT FROM AUTHOR]

Goat breeds from temperate and subtropical latitudes display reproductive seasonal variations. This reproductive seasonality causes a seasonality of milk, cheese, and meat production. To solve this problem, it is necessary to modify the annual season of parturitions. The photoperiod and the socio-sexual interactions can be used to manipulate the caprine reproduction. Therefore, in this review I will describe the photoperiodic treatments used to stimulate the sexual behavior of male goats during the sexual rest. Then, I will describe how these photos stimulated, sexually active bucks, are used to induce the sexual activity of females during the seasonal anestrous or to prevent the seasonal anovulation, allowing does to ovulate all the year round. These techniques constitute an original and sustainable manner to control caprine reproduction.

Tropical animals are characterized by showy ornaments and conspicuous body colours as compared with their temperate relatives. Some recent studies have hypothesized that sexual selection pressures are stronger in the tropics than in the temperate zone. Although negative correlations between latitude and the degree of sexual dimorphism would support this hypothesis, phylogeny should be taken into account in such comparative studies. Comparisons of the degree of sexual dimorphism in body size and fin lengths among species of the Adrianichthyidae, a freshwater fish family having a wide geographical range throughout Southeast and East Asia, revealed that lower latitude species are sexually more dimorphic in all characters than higher latitude species. Phylogenetic generalized least squares analyses using a mitochondrial DNA phylogeny demonstrated that the negative correlations between latitude and the degree of sexual dimorphism become non-significant when phylogeny is considered, but that the variance in the degree of sexual dimorphism is explained not only by phylogeny but also almost equally by latitude. Ancestral state reconstruction indicated that sexual dimorphisms have evolved independently even within major clades. These findings are consistent with the view that tropical species are exposed to stronger sexual selection pressures than temperate species. We discuss possible causes of the latitudinal variation in sexual selection pressure. [ABSTRACT FROM AUTHOR]

In mammals, the melatonin receptor gene has been widely studied since it has a great influence on reproductive traits. However, little is known about the association between polymorphism of the coding region of the MTNR1B gene and year‐round oestrus or the litter size in Small Tail Han sheep. To better understand the effects of single nucleotide polymorphism (SNP) rs400827589 in MTNR1B, a population polymorphism analysis was conducted using genotyping data in 45 sheep breeds around the world. The results indicated that TT was the dominant genotype in all sheep breeds. The associations of this SNP with reproductive seasonality and litter size in Small Tail Han sheep showed rs400827589 was correlated with fecundity as assessed by reproductive seasonality and litter size (p <.05). Bioinformatics analysis indicated the change in amino acid from Ile to Leu may affect the function of the MTNR1B protein by impacting the secondary and tertiary protein structures. The present results demonstrate that rs400827589 could be used in the marker‐assisted selection of the litter size in Small Tail Han sheep. [ABSTRACT FROM AUTHOR]

Wild cattle species, often considered less alluring than certain conservation-dependent species, have not attracted the same level of interest as the charismatic megafauna from the general public, private or corporate donors, and other funding agencies. Currently, most wild cattle populations are vulnerable or threatened with extinction. The implementation of reproductive technologies to maintain genetically healthy cattle populations in situ and ex situ has been considered for more than 30 years. Protocols developed for domestic cattle breeds have been used with some success in various wild cattle species. However, inherent differences in the natural life history of these species makes extrapolation of domestic cattle protocols difficult, and in some cases, minimally effective. Reproductive seasonality, driven by either photoperiod or nutritional resource availability, has significant influence on the success of assisted reproductive technologies (ARTs). This review focuses on the physiological processes that differ in breeding (ovulatory) and non-breeding (anovulatory) seasons in female cattle, and the potential methods used to overcome these challenges. Techniques to be discussed within the context of seasonality include: estrus synchronization and ovulation induction, ovarian superstimulation, artificial insemination (AI), multiple ovulation embryo transfer (MOET), and ovum pick-up (OPU) with in vitro fertilization (IVF) and embryo transfer (ET). • Wild cattle species remain more responsive to environmental cues than domestic cattle. • Reproductive seasonality influences successful implementation of ARTs. • Extrapolation of protocols from a related domestic species to a wild one can be challenging. [ABSTRACT FROM AUTHOR]

Survival rate is one of the most poorly characterized components of the life history of many species of reptiles, especially snakes. Reproductive activity can increase the risk of mortality. In this study, we examined whether sex-specific reproductive costs affect the survival probability of a viviparous rattlesnake, Crotalus triseriatus, in central Mexico from 2015 to 2018. We used a multimodel inference framework to test two hypotheses: (1) female survival probability should decrease during the late-gestation and birthing period, when females are less mobile and try to achieve stable body temperatures by behavioral thermoregulation; and (2) male survival probability should decrease during the mating season, when males are more actively searching for potential mates. Our data did not support these hypotheses. Mean (±1 SE) monthly survival probability of both males and females was 0.96 ± 0.01, and recapture probability was 0.11 ± 0.01. Annual survival rate was 0.72 ± 0.12. Monthly estimated mean adult population size varied from 16 to 71 adult rattlesnakes. Survival probability was positively correlated with body size. The reproductive costs could have been obscured by the fact that females do not reproduce every year and, therefore, the demands of the mating season are not as tightly linked to survivorship as we hypothesized. [ABSTRACT FROM AUTHOR]

Well-nourished spring-born female goats reach puberty in the autumn of the same year. Contrastingly, undernourished spring-born females reach puberty in the autumn of the following year. Therefore, in this study, we reared female goats (undernourished) under semi-extensive management and determined whether the introduction of photostimulated, sexually active males, advances puberty in these females, and whether nutritional supplementation increases the proportion of kidding females. Goats were born on March 30 and weaned at 2 months of age. Then, they grazed natural vegetation from 10:00 to 18:00 each day. Starting in December, two groups did not receive feed supplementation after grazing, whereas two other groups received 600 g daily supplements of a commercial concentrate. In April, one non-supplemented (n = 10) and other supplemented groups (n = 11) were moved indoors and kept in separate pens, where they were joined with sexually active bucks (n = 1 per group). Males were rotated daily between groups for 7 days. Other non-supplemented (n = 8) and supplemented groups (n = 11) were not joined with males. Most of the female goats under study reached puberty (70–100%). However, in supplemented and non-supplemented groups joined with males, puberty commenced much earlier (April) than in those non-exposed to males (September) (P < 0.001). The proportion of pregnant goats did not differ between groups joined with males (P > 0.05), but the proportion of goats that kidded was higher in supplemented (7/11) than in non-supplemented goats (2/10) (P < 0.05). In conclusion, in spring-born goats, the male effect using sexually active males advanced puberty, and nutritional supplementation increased the proportion of kidding goats in females reared under semi-extensive management. • In seasonal female goats, puberty occurs only during the breeding season. • In well-nourished spring-born goats, puberty occurs around 8 months of age. • In undernourished spring-born goats, puberty occurs around 1.5 years of age. • Sexually active bucks induce puberty around 1 year of age. • In females, nutritional supplementation increases kidding rates. [ABSTRACT FROM AUTHOR]

The Rio Grande cooter (Pseudemys gorzugi), the westernmost species of the genus Pseudemys, is a riverine turtle native to the lower Rio Grande River basin and its tributaries. Currently, P. gorzugi is under review by the US Fish and Wildlife Service for federal protection. However, very little is known about any aspect of this species' ecology and natural history, posing challenges to the assessment of its conservation status. To fill in these knowledge gaps, we studied female size at maturity, clutch size and mean egg size, correlation between reproductive output and female size, and reproductive seasonality of P. gorzugi from mid-May to mid-August 2018. We captured P. gorzugi on the Black River, New Mexico, using traditional hoop net traps and snorkeling. Of 155 females, 28 contained oviductal follicles and 16 contained shelled eggs. We observed a high proportion of gravid females at the end of May through mid-June, although the egg development cycle may extend into August. Our findings allow for a better understanding of this poorly studied species. Knowledge on seasonality of egg development and deposition can aid management planners in determining appropriate times for implementing protection for nesting females and nesting sites. [ABSTRACT FROM AUTHOR]

Previous researches have shown that MTNR1A plays an essential role in sheep reproduction. However, most researches focused more on the reproductive seasonality of sheep, and few scientists had studied the association of polymorphisms of the MTNR1A gene with ovine litter size and reproductive seasonality. Therefore, we chose MTNR1A gene to detect its novel sequence polymorphisms and population genetics and analyse their association with seasonal reproduction and litter size in ewes. The mRNA expression level in hypothalamus, pituitary and ovary was also detected. In this study, five polymorphisms (g.15118664G > T, g.15118683C > T, g.15118756C > T, g.15118774C > T and g.15118951G > A) were identified in exon 2. Most importantly, the g.15118683C > T and g.15118951G > A were significant difference between year‐round oestrous sheep and seasonal oestrous sheep (p < .01), and g.15118756C > T had a great effect on litter size of Small Tail Han sheep (p < .05). In addition, the mRNA expression level of MTNR1A in the hypothalamus of polytocous Small Tail Han sheep was significantly higher than that in monotocous Small Tail Han sheep (p < .01) and the expression of MTNR1A in the hypothalamus of year‐round oestrous sheep was significantly higher than that in seasonal oestrous sheep (p < .01). Polymorphisms in exon 2 may regulate the reproductive seasonality and litter size of ewes by influencing gene expression to regulate the reproductive seasonality and litter size of ewes. Our studies provided useful guidance in marker‐assisted selection of the litter size in Small Tail Han sheep. [ABSTRACT FROM AUTHOR]

The fallow deer (Dama dama) is a species of Cervidae commonly kept in captivity, either in commercial farms or in zoos. The reproductive seasonality of this species is well known in the northern hemisphere, where photoperiod is a decisive factor in androgenic activity and, consequently, in the development of secondary sexual characteristics among male adults. The maintenance of this species in tropical regions has been successful, but there are no studies that demonstrate the maintenance of reproductive seasonality under these climatic conditions, which was the objective of the present study. To do so, the present investigation involved 27 fallow deer (D. dama) specimens, of which 14 were adults and 13 prepubescent (<8 months) individuals, all assessed during and outside (December–February) the reproductive season (June–August). The serum concentrations of testosterone, testicular volume, and neck circumference were analyzed among all animals during both seasons. The reproductive season was marked by expressive hormonal concentrations, increasing neck circumference and testicular volume, differing significantly between adults and prepubescent individuals outside the season. Positive correlations were observed among all analyzed variables: mean testicular volume and neck circumference (r = 0.92, p < 0.0001), testicular volume and testosterone concentrations (r = 0.79, p < 0.0001) and between neck circumference and testosterone concentrations (r = 0.67, p < 0.0001). Given the results found, the conclusion is that even under tropical climate conditions the reproductive seasonality of the fallow deer is well defined and may be related to photoperiod. Research Highlights: Male fallow deer (Dama dama) present secondary sexual characteristics related to photoperiodism.Male fallow deer (D. dama) present seasonal variations in a tropical climate region. [ABSTRACT FROM AUTHOR]

Species following a fast life history are expected to express fitness costs mainly as increased mortality, while slow‐lived species should suffer fertility costs. Because observational studies have limited power to disentangle intrinsic and extrinsic factors influencing senescence, we manipulated reproductive effort experimentally in the cavy (Cavia aperea) which produces extremely precocial young. We created two experimental groups: One was allowed continuous reproduction (CR) and the other intermittent reproduction (IR) by removing males at regular intervals. We predicted that the CR females should senesce (and die) earlier and produce either fewer and/or smaller, slower growing offspring per litter than those of the IR group. CR females had 16% more litters during three years than IR females. CR females increased mass and body condition more steeply and both remained higher until the experiment ended. Female survival showed no group difference. Reproductive senescence in litter size, litter mass, and reproductive effort (litter mass/maternal mass) began after about 600 days and was slightly stronger in CR than IR females. Litter size, litter mass, and offspring survival declined with maternal age and were influenced by seasonality. IR females decreased reproductive effort less during cold seasons and only at higher age than CR females. Nevertheless, offspring winter mortality was higher in IR females. Our results show small costs of reproduction despite high reproductive effort, suggesting that under ad libitum food conditions costs depend largely on internal regulation of allocation decisions. [ABSTRACT FROM AUTHOR]

Abstract The aim of this study was to determine whether lower doses than 25 mg of progesterone reduce the frequency of short ovulatory cycles in seasonal anestrous goats exposed to sexually active bucks. Females from the control group were given an im dose of 2 mL olive oil (n = 9). Females from the experimental groups were given an im dose of 1 mg (n = 15), 3 mg (n = 16), 5 mg (n = 15) or 25 mg (n = 16) of progesterone diluted in 2 mL olive oil, 48 h prior exposition to bucks (n = 1 per group). Males were daily switched among groups, and they remained with goats during 21 days. The proportion of goats that ovulated was high (≥87%), and was not different among groups (P > 0.05). In contrast, the proportion of goats that displayed short ovulatory cycles differed among groups (P < 0.05). Indeed, the proportion of goats displaying short ovulatory cycles was lower in those treated with 25 mg (12%) than in those from the control (78%), 1 mg (85%), 3 mg (50%), or 5 mg (71%) groups (P < 0.05), but there were no differences among these last four groups (P > 0.05). Finally, the percentage of kidding females (≥40%) and the number of kids born per female (≥1.4) did not differ among groups (P > 0.05). In conclusion, an im dose of 25 mg of progesterone was more effective than 5, 3 or 1 mg to avoid the short ovulatory cycles in seasonal anestrous goats exposed to the male effect. Highlights • Most of the seasonal anestrous goats exposed to males display short ovulatory cycles. • These short ovulatory cycles are reduced in goats receiving 25 mg of progesterone. • Progesterone doses of 5, 3 or 1 mg do not prevent these short ovulatory cycles. [ABSTRACT FROM AUTHOR]

In rams, artificial long days followed by continuous light stimulate testosterone secretion during the non-breeding season. The objective of this study was to determine whether artificial long days followed by continuous light could stimulate testosterone secretion in Alpine bucks as well as in those exposed to long days followed by a melatonin treatment. All bucks were kept in shaded open pens. Control males were exposed to natural photoperiod conditions (n=5). Males of the two experimental groups were exposed to 2.5 months of long days from 1 December (n=5 each). On 16 February, one group of males was exposed to 24 h of light per day until 30 June; the other group was exposed to natural variations of photoperiod and received two s.c. melatonin implants. Testicular weight was determined every 2 weeks, and the plasma testosterone concentrations once a week. In the control and the two photoperiodic-treated groups, a treatment×time interaction was detected for testicular weight and plasma testosterone concentrations (P

This study assessed whether the seasonal effects of melatonin that upregulate ram reproductive function alter sperm global methylation or protamine deficiency and whether these parameters corresponded to ram endocrinology, semen production and quality. Ejaculates were assessed from rams that received melatonin implants (n = 9) or no implants (n = 9) during the non-breeding season. Ejaculates (n = 2/ram/week) were collected prior to implantation (week 0), 1, 6 and 12 weeks post implantation and during the following breeding season (week 30). Flow cytometry was used to assess the sperm global methylation and protamine deficiency in each ejaculate, which had known values for sperm concentration, motility, morphology, DNA fragmentation, seminal plasma levels of melatonin, anti-Mullerian hormone and inhibin A. Serum levels of testosterone and melatonin were also evaluated. Though there was no effect of melatonin or season, sperm protamine deficiency was negatively correlated with sperm production and seminal plasma levels of anti-Mullerian hormone and positively correlated with sperm DNA fragmentation and morphology. Global methylation of spermatozoa was positively correlated with sperm DNA fragmentation, morphology and serum testosterone and negatively correlated with sperm motility. These moderate associations with sperm production and quality suggest that sperm protamine deficiency and global methylation are indicative of ram testicular function.

The aim of this study was to characterize and identify causative polymorphisms in the leptin receptor (LEPR) gene responsible for the seasonal variation of reproductive traits in sheep. Three reproductive seasonality traits were studied: the total days of anoestrous (TDA), the progesterone cycling months (P4CM) and the oestrous cycling months (OCM). In total, 18 SNPs were detected in 33 ewes with extreme values for TDA and OCM. Six SNPs were non-synonymous substitutions and two of them were predicted in silico as deleterious: rs596133197 and rs403578195. These polymorphisms were then validated in 239 ewes. The SNP rs403578195, located in exon 8 and leading to a change of alanine to glycine (Ala284Gly) in the extracellular domain of the protein, was associated with the OCM trait, being the G allele associated with a decrease of 12 percent of the OCM trait. Haplotype analyses also suggested the involvement of other non-synonymous SNP located in exon 20 (rs405459906). This SNP also produces an amino acid change (Lys1069Glu) in the intracellular domain of the protein and segregates independently of rs403578195. These results confirm for the first time the role of the LEPR gene in sheep reproductive seasonality.

Traditional outdoor pig farming is renowned for its emphasis on animal welfare and the production of highly valued, quality meat. While seasonality is known to impact certain animals, particularly those raised outdoors, there is a lack of research on Bísaro boars, a native Portuguese breed. This research study was conducted on a total of 20 male entire Bísaro pigs, reared in outdoor pens from 4 to 13 months old, and subsequently slaughtered. The animals were divided into two groups: one slaughtered in winter (Wi, n = 9), and the other in summer (Su, n = 11). The objective was to evaluate testicular morphometry, boar taint compounds, and meat quality traits, including sensory analysis and fatty acid profile. Testicles from the Su group exhibited reduced volume, indicating diminished functionality during that season. While no significant differences were observed in the boar taint compound analysis, panelists could discern a more intense aroma and flavor of boar taint in the Su meat. Other meat quality traits showed no significant variations, but the fatty acid profile displayed higher values in the Wi group. This study reveals that Bísaro boars experience reproductive seasonality, leading to variations in boar taint compounds across the seasons. This information is crucial for farm planning., Competing Interests: The authors declare no conflicts of interest.

Prolonged reproductive behavior of American black bears (Ursus americanus) has been reported in the southeastern United States compared with other regions, but functional spermatogenesis or potential fertility has not previously been described for these bears. Additionally, methods for gamete collection are only in early stages of development for ursids. Testicles were collected from 29 post-pubertal legally hunter-killed black bears in eastern North Carolina, USA, in November 2016. Active spermatogenesis was identified in 48.3% (14/29) of bears via histology. Epididymal sperm collection was attempted via mincing (n = 29), vas deferens flush (n = 24), and percutaneous aspiration (n = 5). Epididymal mincing identified sperm in 78.6%, and vas flush in 53.8%, of bears with spermatogenesis on histology. Percutaneous aspiration was unsuccessful. These findings provide evidence that male bears may maintain reproductive capabilities into the late autumn in this region, and that under the conditions of this study, sperm can be collected via epididymal mincing or vas deferens flush, but not percutaneous aspiration. [ABSTRACT FROM AUTHOR]

Abstract: In most goat breeds, testosterone serum concentration and semen quality decrease during the nonbreeding season. However, bucks reproductive activity may be stimulated with the administration of equine chorionic gonadotropin (eCG). Therefore, the aim of this study was to determine whether the repeated administration of eCG stimulates the reproductive status of bucks during the nonbreeding season. The study was performed with 19 bucks that were assigned to a group that was treated with eCG (GeCG) and an untreated control group (GCon). The GeCG bucks received an initial dose of 800 IU of eCG (Day 0), followed by four doses of 500 IU administered every 5 days beginning on Day 5. Serum testosterone and anti‐eCG antibody concentrations, testicular and seminal traits were determined until Day 60. Testosterone concentration (from Day 3 to 21: p < 0.0001), anti‐eCG titre (from Day 12 to 44: p ≤ 0.01), percentage of motile spermatozoa (Day 6: p = 0.006 and 14: p = 0.001) and of spermatozoa with progressive motility (Day 6: p = 0.01 and 14: p = 0.002) and the percentage of spermatozoa with functional membrane (Day 6: p = 0.02 and 22: p = 0.008) were higher in GeCG than in GCon bucks. Also in frozen‐thawed samples, the percentage of motile spermatozoa tended to be higher in GeCG than that of GCon bucks (p = 0.07). In conclusion, the administration of eCG during the nonbreeding season stimulated the secretion of testosterone and improved fresh and possibly frozen‐thawed semen quality. However, it also resulted in an increase in anti‐eCG antibody titre. [ABSTRACT FROM AUTHOR]