Permanent contact with females increases testosterone and improves fresh semen traits in pampas deer (Ozotoceros bezoarticus) males

The environment matters: season and female contact affect the behavior of captive Addax nasomaculatus male antelope

The addax antelope (Addax nasomaculatus) is a species under serious threat of extinction, as it is more abundant in captivity than in the wild. However, little is known about its basic biology. The aims of this study were to determine how locomotor, feeding, aggressive, marking, and sexual behavior of male addax allocated in all-male groups vary with season and with female contact (i.e., biostimulation). The study was conducted in captive conditions, in two groups of adult males: one with no-physical contact with females, aside from visual and olfactory interactions (CF group, n = 4), and another group completely isolated from females (IF group, n = 4). The frequency of behaviors was recorded during the daytime, 4 days per season (total time of observation = 256 h). Lying, standing, walking, aggressive, marking, grazing, and ruminating behaviors as well as water and supplement consumptions varied with season (all p < 0.05). The lying, walking, marking, grazing, and ruminating behaviors were more frequently observed for CF than IF males (all p < 0.05). Also, all behaviors, except for marking, varied with the interaction between the group and seasons (all p < 0.05). Sexual behavior was extremely scarce, so it was not possible to analyze how it varied with seasons and the group. The present study suggests that management program and housing conditions, especially in ex situ breeding plans, should consider the influence of the season and the sociosexual context on the behavior of addax males.

Biostimulation and pheromones in livestock: A review

This review examines aspects of the phenomenon of biostimulation in swine, goats, sheep, cattle and deer, to improve the collective knowledge and exploitation of its relevant mechanisms and effects in animal production. The long-term goal is to implement biostimulation strategies that benefit livestock reproduction and production while being both cost-effective and socially acceptable.

Effects of age, body weight, semen collection frequency and holding duration on semen traits of broiler breeder reared under different housing systems

Semen traits play the vital role in determining the fertility of a broiler breeder flock; however, it can be influenced by several factors. This experiment was carried out to assess some of these factors affecting the semen. A total of 89 male birds and 960 hens of 20-week-old broiler breeder (2215 g ± 7.5%) were divided into two main groups; one was kept in cages (AIC) and another group was kept on deep litter floor (AIF), while both these groups were subjected to AI. The male birds of aforementioned groups (44 males and 480 females) were further divided into 4 sub-groups (11 males and 120 females) to execute different semen collection frequencies i.e., 2, 3, 4, and 5th days' interval. The impact of time duration between semen collection and insemination on sperm kinematics was monitored. The quantitative and qualitative analysis of semen including sperm concentration and sperm kinematics of the collected semen was conducted through a computer-assisted sperm analyzer (CASA) and ONGO machine (working on the CASA principle). Resultantly, the data revealed that the studied parameters of semen were deteriorated with the progression of age of male birds, while the group of males with standard body weight produced the best semen quantitatively and qualitatively followed by overweight particularly during the post peak phase (46-65 = 20 weeks). Although the 3rd day, semen collection frequency was found better for quality, the higher quantity of semen was achieved when males were being collected at the intervals of 4th and 5th day respectively regardless of housing systems. Significant decline in sperm kinematics was recorded with the progression of semen holding duration at the temperature of poultry farm. Furthermore, the highest contamination of E. coli, Salmonella, and Mycoplasma gallisepticum was recorded in the reproductive tract of hens and semen of the AIF group as compared to AIC. Thus, conclusion can be settled that the semen properties are significantly affected by age, body weight, and semen collection intervals in both housing systems, while sperm kinematics is being disrupted with the progression of holding duration. Although housing systems could affect the semen insignificantly, yet lesser contamination was recorded in semen and in the reproductive tract of hens of AIC.

Male-male behavioral interactions drive social-dominance-mediated differences in ejaculate traits

Higher social status is expected to result in fitness benefits as it secures access to potential mates. In promiscuous species, male reproductive success is also determined by an individual’s ability to compete for fertilization after mating by producing high-quality ejaculates. However, the complex relationship between a male’s investment in social status and ejaculates remains unclear. Here, we examine how male social status influences ejaculate quality under a range of social contexts in the pygmy halfbeak Dermogenys collettei, a small, group-living, internally fertilizing freshwater fish. We show that male social status influences ejaculate traits, both in the presence and absence of females. Dominant males produced faster swimming and more viable sperm, two key determinants of ejaculate quality, but only under conditions with frequent male–male behavioral interactions. When male–male interactions were experimentally reduced through the addition of a refuge, differences in ejaculate traits of dominant and subordinate males disappeared. Furthermore, dominant males were in a better condition, growing faster, and possessing larger livers, highlighting a possible condition dependence of competitive traits. Contrary to expectations, female presence or absence did not affect sperm swimming speed or testes mass. Together, these results suggest a positive relationship between social status and ejaculate quality in halfbeaks and highlight that the strength of behavioral interactions between males is a key driver of social-status-dependent differences in ejaculate traits.

Adult and yearling pampas deer stags (Ozotoceros bezoarticus) display mild reproductive seasonal patterns with maximum values in autumn

The pampas deer is an endangered species, from which reproductive biology little is known. We aimed to describe and compare the reproductive seasonal patterns of adult and yearling pampas deer stags throughout the year, including morphological traits, testosterone concentration, sperm morphology and cryoresistance pattern changes. Six adult (AS) and five yearling (YS) stags were captured with anesthetic darts once in winter, spring, summer and autumn to study morphological variables, serum testosterone and semen. Adult males were heavier, their neck girth tended to be greater and their testosterone concentration was higher than in YS. Animals were heavier in summer and autumn. Neck girth and testosterone concentration were greater in autumn. Scrotal circumference, testicular volume and gonado-somatic index varied with seasons, decreasing from winter to spring, increasing in summer and remaining in greater values in autumn. Sperm quality had maximum values from summer to winter. However, the cryoresistance ratio of motility score was greater in spring. In conclusion, in the captivity conditions, pampas deer stags seems to present a light seasonal reproductive pattern, with maximum testis size, testosterone secretion and fresh semen quality in autumn. Nevertheless, sperm cryoresistance ratio seemed to remain stable along the year. Although YS were still growing, they achieved similar semen quality than AS.

The effects of short-term medroxyprogesterone acetate on rut related behaviors, semen characteristics and fertility in farmed reindeer bulls

The effects of medroxyprogesterone acetate (MPA) on velvet antler cleaning, hypophagia, aggressive behavior and fertility were evaluated in farmed reindeer bulls during a 2-year study. Eight reindeer bulls aged 1-4 years were divided into 2 groups balanced for age. During each year, one group (MPA, n = 4) was treated with MPA 2 wk prior to the expected onset of rut while the other group (CTL, n = 4) served as untreated controls. Feed consumption, behavior and antler cleaning were recorded daily or 3 x weekly for 3 mo. Each year a dominant CTL and MPA bull were put into separate harems of estrous synchronized females for 1 wk in mid-September. Following harem breakup, semen was collected from all bulls via electroejaculation and evaluated. In Year 2 the bulls were switched such that year 1 MPA bulls received the CTL treatment and year 1 CTL bulls received MPA treatment. In Year 2 all eight bulls received MPA treatment/booster following semen collection. In both years, MPA treatment reduced rut associated body weight loss (p ≤ 0.05), rut associated hypophagia (p ≤ 0.001), interfered with velvet antler cleaning, and abolished aggressive rut related behavior. All of these changes suggest suppression of testosterone mediated effects. Alternatively, semen parameters differed little between treatment groups with the exception of reduced sperm concentration and total sperm production in MPA bulls (p ≤ 0.05). All CTL bulls in Year 2 exhibited full rut behavior with the dominant bull successfully breeding 100% of females available for breeding, suggesting no carryover effect of MPA treatment from the previous year. The MPA bull successfully bred 4 of 6 females (Year 1) but the MPA bull in Year 2 failed to sire any offspring. A single 400 mg treatment of MPA just prior to rut was sufficient to suppress rut associated aggression and hypophagia on a short-term (3 mo) basis. It did not however, completely suppress fertility.

Immunohistochemical study of arginases 1 and 2 in the olfactory bulbs of the Korean roe deer, Capreolus pygargus

Arginases are enzymes of the urea cycle that catalyze the hydrolysis of l-arginine to ornithine and urea. The enzymes are core components of the arginine-ornithine-glutamate-γ-amino butyric acid pathway of the central nervous system. In the present study, we immunohistochemically determined the localization of arginase 1 and 2 in the olfactory bulb (OB) of the roe dear (Capreolus pygargus). Reverse transcription PCR revealed that the mRNAs encoding both arginase 1 and 2 were expressed in the OB. Arginase 1 was localized to olfactory nerve axons, calcitonin gene-related peptide-positive mitral/tufted cells (excitatory neurons), and glutamate acid decarboxylase 65/67-immunopositive periglomerular cells of the main olfactory bulb. The arginase 2 immunoreactivities in the OB tissues were similar to those of arginase 1. Furthermore, both arginases were detected in the accessory olfactory bulb. These findings suggest that both arginase 1 and 2 are potentially associated with excitatory and inhibitory neurotransmitter activities in animal OBs, including those of the roe deer.

Continuous contact with females in estrus throughout the year enhances testicular activity and improves seminal traits of male goats

The "female effect" consists in the stimulation of males' reproductive activity by different signals emitted by females. This stimulation leads to endocrine and behavioral changes that may modify the seasonal pattern of male ruminants. The aims of this experiment were (1) to describe the local reproductive seasonal pattern of Gabon bucks and (2) to determine if continuous chemical, auditory, and visual contact with does in estrus enhances bucks' testicular activity and improves seminal traits throughout the year and modify their seasonal pattern. We used 16 adult Gabon bucks assigned to two experimental groups: nine bucks remained continuously isolated from females (isolated bucks, group IB) and seven bucks were in continuous chemical, auditory, and visual contact through a fence line with does in estrus (stimulated bucks, group SB). During 13 months, scrotal circumference and testosterone concentration were measured weekly and testicular echogenicity was measured every 2 weeks. Also, sperm motility mass and percentage of abnormal spermatozoa were determined, and sperm concentration and total number of motile spermatozoa were calculated every 2 weeks. Testicular echogenicity was greater in IB than that in SB bucks (P < 0.0001), but there were no differences in scrotal circumference. Overall, testosterone concentration was greater in IB than that in SB bucks (P = 0.04), but from late winter to mid-summer, when testosterone concentration presented basal concentrations, SB bucks had greater values than IB bucks (P = 0.004). Sperm concentration (P = 0.05) and sperm mass motility (P = 0.01) were greater in SB than that in IB bucks, and the total number of progressive motile spermatozoa tended to be greater in SB than in that IB bucks (P = 0.1). The percentage of abnormal spermatozoa was lower in SB than in IB bucks in several time points (P < 0.0001). Testicular and seminal traits were better from the end of the spring until mid-autumn. We concluded that does in estrus stimulated bucks' testicular activity, including better seminal quality and a greater increase of testicular fluid content than bucks isolated from females. However, the general seasonal pattern was not modified by stimulation with does in estrus.

Immunohistochemical localization of GABAergic key molecules in the main olfactory bulb of the Korean roe deer, Capreolus pygargus

Gamma-amino butyric acid (GABA) negatively regulates the excitatory activity of neurons and is a predominant neurotransmitter in the nervous system. The olfactory bulb, the main center in the olfactory system, is modulated by inhibitory interneurons that use GABA as their main neurotransmitter. The present study aimed to evaluate GABAergic transmission in the main olfactory bulb (MOB) of the Korean roe deer (Capreolus pygargus) by examining the immunohistochemical localization of GABAergic key molecules, including glutamic acid decarboxylase (GAD), vesicular GABA transporter (VGAT), GABA transporters (GATs; GAT-1 and GAT-3), and potassium sodium chloride co-transporter 2 (KCC2). GAD, VGAT, and KCC2 were expressed in the glomerular layer (GL), external plexiform layer (ePL), mitral cell layer (ML), and granule cell layer (GrL). Intense GAT-1 expression was observed in the GL; GAT-1 expression was discernible in the ePL, ML, and GrL. However, intense GAT-3 expression was extensively observed in all layers of the MOB. These results suggest that substantial GABAergic synapses are present in the GL, ePL, ML, and GrL. Furthermore, the released GABA may be removed by GAT-1 and GAT-3 in the GL, and the majority of GABA, which is present in the ePL to GrL, may undergo reuptake by GAT-3. This is the first morphological and descriptive study of GABAergic transmission in the MOB of Korean roe deer.

Effect of the presence of hens on roosters sperm variables

This study examines the effect of the presence of hens on sperm variables in Black Barred Andaluza roosters (which respond well to the massage technique). Between 8 and 22 weeks of age, roosters (n = 60) were housed separate from hens in straw litter pens (4 birds/m(2)). Two groups of roosters were then formed to study the effect of hen presence on sperm variables at 36 weeks of age. The first group (n = 11 roosters) was housed with hens (n = 55; sex ratio 1:5), while the second (n = 27 roosters) was again housed separate from hens. Twenty four sperm pools were obtained over 12 weeks (12 pools from each group, each pool produced by mixing semen from 11 males) for analysis. Compared to the no-female-contact group, the roosters living with hens showed significantly (P < 0.05) reduced percentages of non-progressive motile sperm and slow sperm, and significantly increased VCL and VSL values; they also showed trends (P < 0.1) towards increased progressive motility and a higher percentage of rapid sperm. The presence of hens had no significant effect on the number of spermatozoa per ejaculate or sperm concentration. Positive correlations were recorded between VSL and VCL, and between both of these and progressive motility, and the percentage of rapid sperm. In addition, both VSL and VCL correlated negatively with non-progressive motility and the percentage of slow sperm. These results indicate that rooster sperm quality, but not quantity, improves in the presence of hens.

Male reproductive success is correlated with testosterone in the eastern black rhinoceros (Diceros bicornis michaeli)

Among natural populations of polygynous species, males often vary in their lifetime reproductive success. However, in managed populations of endangered species, either in situ or as part of captive breeding programmes, it is important to understand why differences in reproductive success occur. The European captive population of the critically endangered eastern black rhinoceros is currently under-performing relative to their wild counterparts, with low reproductive output and high reproductive skew limiting growth and genetic diversity. To investigate why over 40% of captive males fail to breed, faecal samples were collected weekly from 23 males at 12 institutions across Europe for 4-32 months. Testosterone metabolite concentration was compared between proven and non-proven males and a number of intrinsic and extrinsic factors that could influence reproductive success were also investigated. Males that sired within the last 3½ years had significantly higher androgen concentrations than non-proven males, and average testosterone was positively correlated with the number of offspring sired per year spent in the reproductive age class. Proven and non-proven males did not differ in their body condition, or in average faecal glucocorticoid concentration. Differences in individual temperament were associated with adrenal activity, but did not correlate with reproductive category. Highest testosterone concentrations were observed in proven males that were housed with females during oestrus, and lowest concentrations in non-proven females not housed with females at all during the study period. Further work is necessary to determine whether proven males had higher testosterone due to underlying differences associated with quality, or whether external stimuli such as access to females could influence testosterone concentration and increase a male's chances of becoming a successful breeder.