Scrotal Width Research Articles

Sexual activity and climatic adaptation assessment of West African Dwarf goats introduced into Algeria

This study aimed to highlight the effects of variations in age, seasons and climatic conditions on the reproductive activity of West African Dwarf Goats imported from tropical zones in Algeria, and to verify the degree of their adaptation to Mediterranean climatic conditions. For this purpose, testicular biometry and hormonal analysis (testosterone and LH levels) using the radioimmunological method were carried out monthly. In total, seven goats aged between 18 to 48+ months were surveyed during the period from September 2021 to March 2022. The results showed a considerable effect of age on testicular measurements. Bucks less than 18 months recorded the lowest average testicular length, width, thickness and volume, scrotal width and circumference, as levels of testosterone concentrations. All variables were strong correlated. Seasonal variations in the average testicular measurements and hormonal concentrations were observed, without affecting testicular activity. Apart from thenegative action of ambient temperature, no effects of relative humidity or atmospheric pressure were revealed. West African Dwarf Goats showed a good capacity to adapt to Mediterranean climatic conditions through their continuous testicular activity during the year.

Effect of Age on the Body Parameters, Scrotum, Seminal Characteristics, Spermatozoa Integrity and Sexual Behavior in Ganjam Buck

Background: Bucks raised for breeding purposes receive no special attention and are raised at random without following the correct selection process. Besides, the fertility of the male bucks is never addressed. Goat breeders have noted a sharp decline in the reproductive efficiency of Ganjam goats, associated with a lengthened kidding interval, fewer successful pregnancies and decreased twining frequency. The measurement of male fertility parameters is crucial for estimating the breeding performance of any species since males contribute 50% of the reproductive efficiency. Methods: Six Ganjam bucks of age 1.5(B1), 2(B2), 2.5(B3), 3.5(B4), 4(B5) and 4.5(B6) years procured after selection on the basis of their body morphometry and sexual behaviour were maintained under optimum management practice. They were trained for semen collection. For study on effect age on the semen qualities, they were classified into two age groups and ejaculates were collected during two phases. Bucks of age below 3 were considered under Age group I and bucks older than 3 years were assigned Age group II. Twelve ejaculates from each buck were collected, six ejaculates between the month of July to August and six ejaculates during October to November. The total of 72 ejaculates was evaluated for the study of seminal characteristics. Besides, the external body parameters, scrotal parameters and sexual behaviour of the bucks were also recorded before each semen collection. Result: The bucks of age group II were found to be having significantly higher (p less than 0.01) body weight, mean body length and average value of chest girth than age group I bucks in the present study. The mean value of scrotal width of the bucks of age group II was significantly higher (p less than 0.01) as compared to that of age group I. The mean value of abnormalities of the bucks of age group II was significantly higher (p less than 0.01) than that of age group I. The mean value of acrosome integrity and MBRT of the bucks of age group II was significantly higher (p less than 0.05) to that of age group I. The present study will be helpful in the selection of Ganjam buck at appropriate age for breeding purpose basing on their body parameters, scrotum, seminal characteristics, spermatozoa integrity and sexual behavior.

Effect of Season on the Scrotum, Seminal Characteristics, Spermatozoa Integrity and Sexual Behavior in Ganjam Buck

Background: Bucks raised for breeding purposes receive no special attention and are raised at random without following the correct selection process. Besides, the fertility of the male bucks is never addressed. Goat breeders have noted a sharp decline in the reproductive efficiency of Ganjam goats, associated with a lengthened kidding interval, fewer successful pregnancies and decreased twining frequency. The measurement of male fertility parameters is crucial for estimating the breeding performance of any species since males contribute 50% of the reproductive efficiency. Methods: A total of 120 Ganjam bucks of different age groups reared by the local farmers of Rambha, Khalikote and Chhatrapur areas of Ganjam district were used for the present study. A total of six healthier bucks of age 1.5(B1), 2(B2), 2.5(B3), 3.5(B4), 4(B5) and 4.5(B6) years were procured from the Farmers for the experimental purpose. For study on effect of season on the semen qualities, twelve ejaculates from each buck were collected, six ejaculates between the month of July to August (season 1) and six ejaculates during October to November (Season 2). Result: The scrotal length, scrotal width, scrotal circumference have highly significant positive degree of association with Flehmen’s reaction and Libido score and all the parameters exhibited highly significant negative degree of association with reaction time. Moreover, the scrotal length, scrotal width and scrotal circumference had significantly higher positive degree of association with colour, volume of the semen and negative degree of association with MBRT. Further, the sperm concentration revealed a highly significant degree of association with scrotal length, scrotal width, scrotal circumference, livability % and acrosome integrity and a significant degree of association with mass activity. Livability % of the semen samples of the six bucks revealed a highly significant degree of association with scrotal length, scrotal width, scrotal circumference, sperm concentration and acrosome integrity.

286 Impact of feeding strategies on bodyweight and body condition in mature AI boars

Abstract The objective of this experiment was to determine how varying feeding strategies for boars impacts body weight (BW), backfat depth, loin muscle depth, Knauer caliper measurements, flank to flank tape measurement, body condition score (BCS), and scrotal width and length. This experiment was conducted over two 9-wk periods. Boars were weighed and measurements were taken every 3 wk during the study. Boars (n = 28; Acuity and Topig Norvsin) from two age groups (9 and 15 mo) and two genetic lines (maternal and terminal) were used during this experiment. Boars were blocked by breed and age and randomly allocated to receive one of the three feed intake (FI) levels of a corn-soybean meal-based diet (met NRC 2012 nutrient requirements) using the NRC (2012) maintenance equation [ME for maintenance = (100*kg BW0.75) + 15 kcal for sperm production]. Treatments were: HIGH (150% of maintenance, n = 9), MAIN (100% of maintenance, n = 10), LOW (80% of maintenance, n = 9) for the first 9-wk period. During the second 9-wk period remaining HIGH and LOW boars were crossed-over to opposite treatments (HIGH-LOW, n = 9; LOW-HIGH, n = 7) and maintenance remained unchanged (MAIN-MAIN, n = 8). Data were analyzed using PROC MIXED in SAS 9.4. Boar was the experimental unit with main effects of feed intake and age, and week serving as a repeated measure. Significance was determined at P < 0.05 and a trend at 0.05 < P ≤ 0.10. Three-way interactions of FI*Age*Week were observed during the first 9-wk period. Young boars fed HIGH had a greater increase in BW (P = 0.002), caliper (P = 0.011), backfat depth (P = 0.003), BCS (P = 0.003), and scrotal width (P = 0.004) than old boars fed HIGH and young boars fed LOW had a greater reduction in these variables then old LOW boars. Boars fed LOW for the first 9-wk period had reduced scrotal length (P = 0.004), greater reduction in BW change (P < 0.001), and reduced tape change (P = 0.021) compared with HIGH and MAIN fed boars. Two-way interactions for the second 9-wk period were observed. HIGH-LOW fed boars had decreased BW (FI*Week; P < 0.001), tape (FI*Week; P = 0.019), caliper (FI*Week; P = 0.012), BCS (FI*Week; P < 0.001), and scrotal width (FI*Week; P = 0.047) while LOW-HIGH boars had increased measurements for these variables over time. Additional two-way interactions during the second 9-wk period included Tape (FI*Age; P = 0.046) and BCS (FI*Age; P = 0.028). Overall young boars had more adverse reactions to the varying feeding strategies than old boars, this included larger changes in BW and composition measures. Young and old boars fed MAIN level lost BW and condition indicating the equation for maintenance energy requirement is not accurate for modern genetics working boars. Future research is needed with varying ages and feed intakes in the boar stud to better understand the impacts of growth, development, and maintenance energy for the modern AI boar.

PSI-8 Impact of feeding level on boars from selection to entering the boar stud on trainability and growth measurements

Abstract The objective of this study was to determine if restricting feed in boars at selection impacts growth of boars or training for semen collection. Duroc boars (n = 25) randomly allotted at 6 mo of age to receive one of two levels of restricted feeding (1.8 kg/d, n = 12 or 2.72 kg/d, n = 13) of a corn-soybean meal-based diet formulated to meet NRC (2012) requirements. Diets were fed for 9 wk before training for semen collection where body weight (BW), body condition score (BCS), flank-flank tape measurements, Knauer sow caliper, loin muscle depth, backfat depth, and scrotal width and length were collected every 3 wk. Training for semen collection was conducted 5 d/wk for 2 wk. Boars were given 10 min in the collection pen to successfully mount the dummy and start collection each training session. Training was scored on a scale of 1-5, 1 = no interest and 5 = successful collection. After three successful collections in a row, boars were considered fully trained. All boars had their first production collection on wk 12. Data were analyzed using PROC MIXED and PROC FREQ chi-square in SAS 9.4 with boar serving as experimental unit. Weeks were analyzed individually and overall changes were evaluated. Significance was determined at P < 0.05 and a trend was observed at 0.05 < P ≤ 0.10. Boars fed 2.72 kg/d had increased BW on wk 9 (P < 0.05) and wk 12 (163.6 kg vs 149.8 kg, SE = 2.17; P < 0.001), increased BW gain wk 1-9 (P < 0.01), wk 9-12 (P < 0.001), and overall (49.8 kg vs 34.4 kg, SE = 1.60; P < 0.0001). The 2.72 kg/d boars also had increased backfat depth on wk 9 (P < 0.01) and wk 12 (8.4 mm vs 7.5 mm, SE = 0.17; P < 0.001), larger caliper scores on wk 12 (P < 0.01), greater flank-flank distance on wk 9 (P < 0.01), and increased BCS on wk 12 (3.2 vs 2.7, SE = 0.14; P < 0.01). No differences were observed for loin muscle depth, or scrotal width and length. Feeding level did not affect trainability with approximately 92% of boars being trained at the end of the two-week period in both feeding levels. Boars fed 2.72 kg/d had increased semen volume (128 mL vs 81 mL, SE = 12.1; P < 0.01) on their first production collection on wk 12 with no effects on other semen quality parameters. Overall, feeding boars 1.8 kg/d for 12 weeks following selection resulted in lower body weight and composition measures indicating limit feeding boars at selection could be used to slow growth rates, potentially decreasing structural issues, and increasing longevity of growing boars in the boar stud, with no effects on training for semen collection. Future research is needed to investigate the long-term impacts of the degree of limit feeding growing boars following selection on lifetime semen quality and quantity. Keywords boar, management, nutrition

Nonlinear Models to Describe the Testicular Size Growth Curve of Mangalarga Marchador Stallions

This study aimed to describe the testicular growth curve in Mangalarga Marchador stallions fitting nonlinear models to data of total scrotal width (TSW) and testicular volume (TV). A cross-sectional study was conducted with 120 stallions, aging from 1.75 to 21.93 years. The parameters of nonlinear models (Brody, Gompertz, Hill, Logistic I and II, Meloun I and II, Michaelis-Menten, Mitscherlich, and von-Bertalanffy) were estimated by Gauss-Newton iterative process. Goodness of fit was evaluated by the corrected Akaike (AICc) and Bayesian (BIC) information criteria, adjusted R2, error sum of square, mean absolute deviation and average prediction error. Based on the goodness of fit, the Logistic I model fitted better for TSW while Logistic II fitted better for TV growth curve. The inflection point (IP) of TSW growth was estimated in 5.23 cm at 0.76 years; the IP of TV growth was estimated in 139.36 cm3 at 2.57 years. The TV growth curve reached a plateau later than TSW growth curve, mainly because testicular height maintains growth for a longer period. In addition, there were moderate and positive correlations between whiter height and TSW and TV (r = 0.51 and r = 0.53, respectively). Findings suggest that TV is more associated with sexual maturity than sexual precocity. In addition, the moderate and positive correlations between whiter height and TSW and TV indicate that testicular traits can be included in selection programs of Mangalarga Marchador stallions with the same relevance as the morphometric traits.

140 The relationship between morphometric characteristics and semen parameters in Bapedi rams

Bapedi is a fat-tailed, hardy, and disease-tolerant breed of sheep that is indigenous to South Africa. The Bapedi sheep breed is facing genetic degradation due to nonselective cross-breeding and irregular mating; therefore, breeding strategies for urgent conservation of Bapedi sheep are crucial. The aim of the present study was to investigate the relationship between body measurements and semen traits of Bapedi rams conserved in situ (conserved in their natural habitat) and ex situ invivo (live animals conserved outside their natural habitat). Semen was collected twice per week from 33 rams aged 2-4 years (four ejaculates per ram) using an electroejaculator. Body measurements (rump height, body length, scrotum circumference (SC), scrotal width, and scrotum length (cm)), body condition score (BCS; scale of 1-5), bodyweight (BW; kg), rectal temperature (°C), semen volume (mL), spermatozoa concentration (billionsmL−1), and motility parameters were measured using a computer-aided semen analysis system. Data were analysed using analysis of variance and the general linear models of SAS (SAS Institute Inc.). The Pearson correlation coefficient in SAS was used to determine the relationship among variables. There was uniformity in all body measurements of Bapedi sheep regardless of the conservation method (P>0.05). There were no significant differences in body temperature during semen collection, SC, semen volume, semen pH, semen concentration, spermatozoa total motility, and kinematics in Bapedi rams between methods of conservation (P>0.05). Pearson correlation revealed moderate significant relationships between semen volume and BW, BCS, and SC (r=0.315, 0.638, and 0.381, respectively). Rump length had a moderate correlation (0.566) with normal spermatozoa (P<0.05). It was concluded that Bapedi sheep are still a uniform breed regardless of their decreasing numbers. The BW, BCS, and SC must be considered in the selection criteria for improving the reproductive performance of Bapedi breeding rams because they were positively correlated with semen volume. It is recommended that more studies be done to correlate body measurements, testicular morphometry, and semen parameters in this breed.

17 Relationship Between Semen Parameters and Morphometric Characteristics of Zulu Rams

Zulu sheep is an adapted breed of South Africa with desirable traits such as their ability to thrive in a harsh environment and tolerant to various diseases. However, they are endangered, with their population size not exceeding 1000, and hence are associated with high inbreeding rates. Therefore, to limit biodiversity loss, there is a need to characterise and conserve its genetic materials. The aim of the study was to evaluate the relationship between morphometric characteristics and semen parameters of Zulu rams and conserve these genetics. The study was conducted at the Agricultural Research Council. Rams (n = 6, age = 3 years and average weight = 42 kg) were fed a standard diet and water was provided ad libitum. Semen was collected twice a week, using an artificial vagina, over 4 consecutive weeks. Semen volume, spermatozoa concentration, motility parameters, and viability were evaluated immediately after arrival in the laboratory. The experiment was carried out during breeding season (March to May 2017). Body measurements (rump height, body length, scrotum circumference, body weight, scrotal width, and scrotum length) were measured in the morning following the fasting period (night) using flexible measuring tape. Pearson correlation coefficient in Minitab 17 (Minitab Inc., State College, PA, USA) was used to determine the relationship among variables. A moderate significant correlation (P < 0.001) between body weight and %live spermatozoa (r = 0.46) was observed. Of note, a very weak (r = 0.28) significant correlation (P < 0.05) between scrotum circumference and live spermatozoa was observed. A very weak (r = 0.06) nonsignificant correlation (P > 0.05) was found between scrotum circumference and semen volume. These results indicate that body weight and scrotum circumference provide reliable spermatozoa viability estimates. Positive correlation between scrotum circumference and semen volume shows that scrotum circumference can be used to predict semen volume.

The use of ultrasonography in the reproductive evaluation of boars.

The objective was to study the use of ultrasound as a complementary test in the breeding soundness evaluation in male pigs and study the pattern of echogenicity of the testicular parenchyma in boars of different racial groups. Twenty-six adult boars from four different racial groups were used, 10 from the Piau breed (group 1), four from the commercial and finishing group (group 2), six Pietrain breed (group 3) and six from the Duroc breed (group 4). All animals were evaluated for breeding soundness evaluation and the ultrasound examination of the testicles. The groups of animals that were evaluated showed no difference in the main semen parameters that were evaluated, except for the sperm volume, concentration of the ejaculated sperm and the supravital staining; the lowest figures were for the animals from the Piau breed (group 1). In relation to the testicular biometrics, Duroc animals (group 4) had a greater scrotal width compared to the other groups. But when we assessed the intensity of pixels of the testicles, there was a difference between groups. The groups 2 (finishing animals), 3 (Pietrain) and 4 had no difference between themselves. Group 3 had greater pixel intensity in relation to group 1. Of the 26 animals studied, five showed an abnormality during ultrasound evaluation, like hydrocele, hyperechoic mass in the testicular parenchyma, cyst in the head of the epididymis and the presence of fluid in the head and tail of the epididymis. The various animal groups studied did not differ in the principal reproductive parameters evaluated, showing that despite the great variability of reproductive traits between breeds and within the same breed, the breeding soundness evaluation, the more complete it is, is essential for the selection of breeders and the ultrasonography of the reproductive system becomes an important addition in this examination.

Two complementary methods to control gonadotropin-releasing hormone vaccination (Improvac®) misuse in horseracing: Enzyme-linked immunosorbent assay test in plasma and steroidomics in urine.

Since the availability on the European market of the vaccine Improvac® dedicated to male pig immunological castration, the risk of misuse of this product in horses is now considered as a threat for the horseracing industry. Immunological castration is not allowed by the racing codes (immune system, Article 6). Indeed, this vaccination against the hypothalamic hormone luteinizing hormone-releasing hormone or gonadotropin-releasing hormone (GnRH) will prevent the release from the anterior pituitary of luteinizing hormone and follicle stimulating hormone, which are required for the development and activity of gonads in males (testes) and female (ovaries) and therefore all their subsequent physiological functions. This treatment will induce a strong hormonal variation resulting in a behaviour modification of the animals. In this work, four male standardbreds treated with Improvac® vaccine (two intramuscular injections within 4weeks) were studied. Monitoring of the total scrotal width showed a decrease of the scrotum size (37%) and production of anti-GnRH antibodies was detected up to 200days after the first injection. Anti-GnRH antibodies were detected in plasma after caprylic acid precipitation followed by an enzyme-linked immunosorbent assay (ELISA) as a rapid and efficient screening method applicable to routine analysis. These results were correlated to a switch of the sexual status from male group to gelding/female group obtained by a steroidomic approach with urine based on ten endogenous compounds. Copyright © 2017 John Wiley & Sons, Ltd.

Ultrasound as tool for diagnosis of diseases of the reproductive tract bulls

Abstract The purpose of this study was to evaluate by ultrasound and breeding soundness examination (BSE) the major diseases affecting the reproductive system of Nelore bulls, bred extensively in the state of Para, Brazil. Fifty-nine pure Nelore bulls were used, aged between 5 to 10 years, raised extensively in a commercial farm in the municipality of Paragominas, Para state, Brazil. Scrotal circumference, testicular length and width were measured. Semen collection for evaluation of ejaculate volume, turbulence, motility, vigor, concentration and sperm pathologies was performed. Ultrasound examination was performed by equipment type Ultrasonic Transducer - CHISON/D600vet, linear transducers, where the frequency used was 5 MHz, being held two images of each testis, the longitudinal-lateral, lateral and transverse planes. The images were processed using the program Image J. The data were analyzed using the statistical program SAS (2000) and means were compared using Tukey's test (p 0.05). Thus, it can be concluded that ultrasonography is an essential complementary tool in the diagnosis of reproductive disorders in animals subjected to BSE and its use should be recommended.

EFFECT OF MUCUNA (Mucuna pruriens) ON SPERMIOGRAMS OF WEST AFRICAN DWARF BUCKS

<p>The study was carried out to investigate the potential effect of <em>Mucuna pruriens</em> seed powder on spermiograms of West African Dwarf bucks (WAD). Twenty bucks were randomly assigned to five treatments consisting of four animals each receiving 0, 25, 50, 75, 100mg/Bw of <em>Mucuna pruriens</em> seed powder administered via oral route for 30 days consecutively. Following treatment, spermiograms of the animals were determined. The results showed that exposure of bucks to <em>Mucuna pruriens</em> powder led to a significant increase in weight gain, scrotal width, scrotal circumference, testicular weight, gonadosomatic index, sperm motility and testicular parenchyma of animals compared to the control and the improvement in these parameters was much pronounced in bucks that received 75mg<em> Mucuna pruriens</em> seed powder (<em>P</em><0.05). Higher (P<0.05) sperm concentration was observed in 100mg inclusion of <em>Mucuna pruriens</em> seed powder compared to other treatments. The results showed a decline (P<0.05) in the level of testosterone with increasing level of <em>Mucuna pruriens</em> seed powder administration. The findings showed that oral administration of <em>Mucuna pruriens </em>seed powder<em> </em>to the bucks for 30 days resulted in improved testicular measurements and sperm quality without any adverse effect on structure of reproductive physiology of the bucks.</p>

What can I give to calm this stallion down?

What can <scp>I</scp> give to calm this stallion down?

Effect of Scrotal Insulation Associated to Environmental Discomfort on Andrologic Characteristics in Santa In&amp;#234;s Rams

The present study was performed with the objective to evaluate the effect of scrotal temperature elevation under condition of environmental discomfort (high temperature and humidity) in Santa Ines rams. This inedited study was conducted in Amazonian region during the rainiest period of the year, characterized by high temperature and humidity; condition related to thermal discomfort of the four rams used. The breeding soundness evaluations (BSE) (scrotal-testicular-epididymal biometry and seminal and libido evaluation) were realized before and after the scrotal insulation. The injury resulted in a decrease in the biometric values of scrotal circumference, length, width and testicular volume, between the period of pre-insulation and the one week after the damage (P

Evaluation of noninvasive methods of predicting testicular weight and development in an inbred and outbred strain of laboratory mouse

Testicular weight is a valuable measure of gonadal development in laboratory mice, but is usually only obtainable postmortem. The objective was to assess the utility of antemortem, noninvasive methods of predicting testicular weight and volume in peripubertal mice. Body weight, scrotal width, and ultrasonographic testicular diameter measurements were obtained in situ in euthanized male outbred (CD-1: N = 20) and inbred (BALB/c: N = 20) mice and compared with excised testicular weight and diameter. In these two strains, body weight predicted mean testicular weight (r2 = 0.810; P < 0.0001 and r2 = 0.943; P < 0.0001, respectively). Scrotal width (lateral margins of the scrotum) was a more reliable indicator of excised mean testicular weight (CD-1: r2 = 0.885; P < 0.0001; BALB/c: r2 = 0.861; P < 0.0001) than measurements of testicular diameter obtained via ultrasound (CD-1: r2 = 0.597; P < 0.0001: BALB/c: r2 = 0.478, P < 0.01) in both strains. Obtaining scrotal width measurements also required less time and restraint than ultrasonography. In live, conscious animals (10 of each strain), the association of scrotal width to testicular weight remained high (CD-1: r2 = 0.906; P < 0.0001; BALB/c: r2 = 0.918; P < 0.0001). Predicted testicular weights derived from scrotal width measurements differentiated animals in three stages of advanced spermiogenesis (CD-1: N = 30; P < 0.0001; BALB/c: N = 30; P < 0.0001). Based on these findings, in vivo scrotal width can be used for noninvasive, in situ prediction of testicular weight in peripubertal laboratory mice. It also has potential application in staging testicular development on a quantitative scale, which would complement using balanopreputial separation as a single indicator of puberty. As a more direct measure of testicular size, this parameter will also be less affected by endogenous and exogenous influences than body weight. Ultimately, using noninvasive in vivo methods of predicting testicular weight should reduce the number of animals required for studies focused on testicular development.

Use of Multiplanar 3-Dimensional Ultrasonography for Prenatal Sex Identification

Determination of fetal sex is an important part of detailed second-trimester ultrasonography. This task can be hindered by the fetal position, a low amniotic fluid volume, and advanced gestational age. Identification of fetal sex is further important in multiple gestations and prior histories of indeterminate-sex pregnancies. The goal of the study was to compare the effectiveness of 2-dimensional ultrasonography (2DUS) versus 3-dimensional ultrasonography (3DUS) at sex identification and to determine how genitalia measurements taken with 3DUS technology compare with measurements taken with 2DUS. A total of 111 patients at or beyond 16 weeks' gestation were recruited. Assignments of fetal sex using 2DUS and 3DUS were compared by the test of proportions. The actual neonatal sex was obtained after delivery. Given such small number of misdiagnoses by either 2DUS or 3DUS, the accuracies of the two modalities were not found to be statistically distinguishable from one another (P = .5585). The penile length, scrotal width, and bilabial diameter according to gestational age were measured and compared with previously published 2DUS data by t tests. Sexes were assigned and interpreted in 65 cases. Ranges of genitalia measurements were plotted against gestational age and were found to be comparable with published data. There was a dramatic difference between the bilabial diameter and scrotal width with advancing gestational age that made sex determination much easier in the third trimester. Although 3DUS did not have better prediction of fetal sex when compared with 2DUS, it may be a useful tool in conjunction with traditional imaging techniques in assigning fetal sex.

Who's your daddy? Paternity testing reveals promiscuity and multiple paternity in the carnivorous marsupial Dasyurus maculatus (Marsupialia: Dasyuridae)

Female promiscuity is common among mammals but its advantages, particularly for marsupials, remain unclear. Using microsatellite DNA from pouch young of known mothers, we identified the most likely fathers of 25 wild spotted-tailed quolls (Dasyurus maculatus) from six litters. We aimed to determine whether young within the same litter had different fathers, and whether breeding success of males was associated with large body mass (consistent with inter-male competition) or scrotal width (consistent with sperm competition). We also explored the possible influence of promiscuity on relatedness within litters. Finally, we used data on paternity and relatedness to make inferences regarding movement and dispersal. Four litters were sired by more than one male, and three males sired offspring in more than one litter. Known fathers had higher body mass, but not scrotal width, than males of unknown paternity status, suggesting that males may compete for access to females. Sires were less related to dams than expected by chance, and litters with multiple paternity had lower relatedness than litters sired by a single male. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 1–7.

Suppression of testicular function and sexual behavior by vaccination against GnRH (Equity™) in the adult stallion

The aim of this study was to evaluate the effects of an anti-GnRH vaccine on testosterone concentration, antibody titer, scrotal width, semen quality and sexual behavior in the stallion. Adverse reactions to the vaccine were also determined. Eight clinically healthy sexually experienced stallions aged between 6 and 15 years from the National Stud in Avenches (Switzerland) were used. Five stallions were immunized 3 times at an interval of 4 and 8 weeks, respectively, with 200 μg of a GnRH-protein conjugate (Equity™, CSL Limited, Australia) intramuscularly in the neck and 3 control animals received an equivalent volume of saline solution. Plasma testosterone concentrations and GnRH antibody titers as well as semen quality and libido were determined weekly during 1 year (52 weeks). In addition, scrotal width was measured in all stallions before and 4, 8 as well as 12 months after first vaccination. Our results demonstrate that in 4 stallions plasma testosterone started to decrease after the second vaccination and remained suppressed for at least 6 months whereas one stallion showed no effect. Until the end of the experiment 2 stallions reached prevaccination testosterone values. Antibody titers varied individually in all 5 stallions and reached peak concentrations within 2 weeks after the third vaccination. Scrotal width was significantly ( P < 0.05) lower in vaccinated than in control stallions 8 months after first vaccination. Semen quality started to decreased after the second vaccination and improved towards the end of the experiment. In 4 stallions libido was clearly reduced after the second immunization but normalized in 2 animals before the end of the study while 2 stallions continued to show poor libido. From our results we conclude that three immunizations with Equity™ are well tolerated in the stallion and may effectively suppress testosterone secretion and reduce semen quality as well as sexual behavior. The inhibiting activity of Equity™ on these parameters is individually different and may last for a minimum of 6 months.

Reproductive patterns of stray male dogs in the tropics

Two studies were performed to determine annual reproductive patterns in stray male dogs in the tropics. In Study 1, four dogs housed individually outdoors were monitored once monthly for 12 months, including collection and assessment of semen, measurements of scrotal width, and determination of serum testosterone and prolactin concentrations. In Study 2 (conducted concurrently), a single blood sample (for serum testosterone concentration) was collected from 220 clinically healthy dogs, and after euthanasia, scrotal width and morphology of epididymal sperm were determined. The year was divided into three seasons: warm–dry (March to June); warm–humid (July to October) and fresh–humid (November to February). In Study 1, scrotal width, ejaculate volume, sperm count and motility were significantly lower during the fresh–humid season and sperm midpiece abnormalities were significantly more common during the warm–humid and fresh–humid seasons. Serum testosterone concentrations remained constant during the year. Prolactin concentrations did not differ significantly among seasons, but had a well-defined increase from the beginning of March to the end of August. In Study 2, sperm morphology was similar to in Study 1 and serum testosterone concentrations varied nonsignificantly during the year. Environmental factors, e.g. daylength may have influenced circannual changes in prolactin secretion. Seasonal variations in some reproductive tract and seminal traits were significant but of small magnitude and the percentage of morphologically normal sperm did not vary significantly among seasons. In conclusion, healthy male dogs constantly produced sperm and were apparently fertile throughout the year.

Estação de nascimento e puberdade em cordeiros Santa Inês

Neste estudo, investigou-se o efeito da estação de nascimento sobre a puberdade de cordeiros Santa Inês criados no Distrito Federal. Utilizaram-se 33 cordeiros machos, inteiros, distribuídos em quatro lotes de grupos contemporâneos. A diferença de idade de cada grupo foi de 90 dias, abrangendo as quatro estações do ano. Foram realizadas coletas de dados mensalmente e a cada 15 dias, dependendo da presença ou ausência de espermatozóides no ejaculado de cada animal. A puberdade foi definida quando o sêmen do animal apresentou motilidade total de 10% e concentração espermática de 50 x 10(6) espermatozóides por mililitro (mL) de ejaculado. Após a definição da puberdade, procedeu-se a mais uma coleta e, após 15 dias, realizou-se a castração dos animais. A idade à puberdade dos animais foi de 194,57 ± 41,97 dias. A estação do ano afetou a idade à puberdade entre os grupos, principalmente em razão do fator nutricional, visto que os pesos à puberdade foram semelhantes. O grupo mais precoce (nascido em agosto) apresentou idade à puberdade de 162,56 ± 35,55 dias. Correlações significativas foram encontradas entre peso e circunferência escrotal (CE), comprimento e largura testicular, sugerindo que a CE pode ser utilizada como critério complementar para a seleção feita com base nos parâmetros produtivos.