Histological structure and age-related changes in the luminal diameter of the excurrent duct system of guinea cocks (Numida meleagris) and associated changes in testosterone concentrations.

As little information is available on the reproductive system of guinea fowl (Numida meleagris), a study was conducted on 49 male guinea fowl to document the histological structure and developmental changes in the luminal diameter of the ducts within the excurrent duct system and associated changes in concentrations of testosterone. Age-related changes were analyzed using the Kruskal-Wallis test and medians separated by the Mann-Whitney U-test. Tubuli recti were clearly visible in the guinea fowl and the rete testes were both intracapsular and extracapsular. Regardless of age, the luminal diameter of the proximal ductuli efferentes was the largest, while that of the connecting duct was the smallest. The luminal diameter of all ducts within the epididymal region increased (P < 0.001) monthly until 20 wk of age, and then increased marginally every month thereafter. Peripheral testosterone concentrations also peaked at 20 wk of age and declined thereafter. In adult birds, the ductus deferens enlarged posteriorly, from an average of about 279 µm cranially to 678 µm caudally. Peripheral testosterone concentrations strongly and positively correlated with the luminal diameter of ducts within the excurrent duct system. The pattern of increase in the luminal diameter of all ducts followed the pattern of testosterone secretion in these birds, which indicates that testosterone concentrations may be closely related to the development of the excurrent duct system in male guinea fowl.

Étant donné le peu d'informations disponibles sur le système reproducteur de la pintade (Numida meleagridis), une étude a été menée sur 49 pintades mâles afin de documenter la structure histologique et les changements développementaux dans le diamètre de la lumière des tubes à l'intérieur du système de tubes excréteurs et les changements associés dans les concentrations de testostérone. Les changements associés à l'âge ont été analysés par le test de Kruskal-Wallis et les médianes séparées par le test de U de Mann-Whitney. Les tubes droits étaient clairement visibles chez les pintades et les rete testis étaient intracapsulaires et extracapsulaires. Indépendamment de l'âge, le diamètre de la lumière des canaux efférents était le plus large, alors que celui du canal connecteur était le plus petit. Le diamètre de la lumière de tous les canaux à l'intérieur de la région de l'épididyme a augmenté (P < 0,001) mensuellement jusqu'à 20 semaines d'âge, et augmenta par la suite de manière marginale à chaque mois. Les concentrations périphériques de testostérone ont également atteint un pic à 20 sem d'âge et ont décliné par la suite. Chez les oiseaux adultes, le canal déférent s'élargissait postérieurement, d'une moyenne d'environ 279 µm cranialement jusqu'à 678 µm caudalement. Les concentrations périphériques de testostérone corrélaient fortement et positivement avec le diamètre de la lumière des canaux dans le système de tubes excréteurs. Le patron de l'augmentation de la lumière de tous les canaux suivait le patron de sécrétion de testostérone chez ces oiseaux, ce qui indique que les concentrations de testostérone pourraient être intiment associées au développement du système de tubes excréteurs chez la pintade mâle.(Traduit par Docteur Serge Messier).

Age-related changes in the gross anatomy of the reproductive organs, and associated steroid hormone profiles in male and female guinea fowls (Numida meleagris).

Owing to the paucity of information on the reproductive biology of guinea fowls, a study involving a total of 132 birds was conducted, and this documented the developmental changes in the gross anatomy of the reproductive organs of males and females from hatching until 32 weeks of age (WOA), and associated steroid hormone changes. Testicular anatomical biometric traits increased significantly (p < 0.0001) from 8 WOA, and stabilised between 16 and 20 WOA, while peripheral testosterone concentration peaked at 20 WOA. Correlations among all testicular biometric characteristics were strong and positive (p < 0.0001). Similarly peripheral testosterone concentrations strongly (p < 0.01) and positively correlated with all the testicular anatomical biometric traits. In the female guinea fowl, the ovary and oviduct were discernible and measurable at hatching. Significant (p < 0.0001) increases were seen in ovarian and relative ovarian weights, and oviducal weights and lengths between 24 and 28 WOA. Plasma 17ß-oestradiol decreased gradually to a very minimum at 16 WOA, and then began to increase gradually until 28 WOA when it plateaued. Peripheral progesterone concentrations on the other hand increased gradually from 4 WOA and peaked at 12 WOA, and then fluctuated considerably thereafter. Correlations among ovarian/oviducal anatomical parameters were strong (p < 0.0001) and positive. Similarly, peripheral oestradiol concentrations strongly (p < 0.0001) and positively correlated with all ovarian/oviducal anatomical parameters. Testicular anatomical biometric traits stabilised between 16 and 20 WOA, coinciding with peak peripheral testosterone concentrations, while ovarian/oviducal parameters recorded huge increases between 24 and 28 WOA, and may be under the influence of oestradiol.

Developmental changes in the histological structure of the testes, and testosterone profiles in male guinea fowls (Numida meleagris).

Owing to the paucity of information on the reproductive biology of guinea fowls, a study involving a total of 66 males was conducted, and documented the developmental changes in histological structure of the testes of guinea cocks from hatching until adulthood. Changes in testosterone synthesis during sexual development were also determined. Age-related changes were analysed using univariate analysis for completely randomised design and means separated using Tukey's test/Kruskal-Wallis test and medians separated by Mann-Whitney U test. Total germ cell population per testis and testicular histological morphometric parameters increased significantly (p < 0.0001) from 12 weeks of age (WOA), and stabilized between 20 and 24 WOA. Peripheral testosterone concentrations increased gradually from 4 WOA, and peaked at 20 WOA. Correlations among all the testicular morphometric parameters were positive and highly significant (p < 0.01). Similarly, significant (p < 0.05) positive correlations existed between testicular weight and testicular sperm production, tubular diameter, Sertoli cell population, tubular length and peripheral testosterone concentration. Testicular sperm production was positively correlated with meiotic index (p < 0.01) and round spermatids population (p < 0.05). The correlations between peripheral testosterone concentrations, tubular diameter and Sertoli efficiency were also significant (p < 0.05) and positive. Testicular morphometric parameters stabilized between 20 and 24 WOA, while peripheral testosterone concentrations showed two patterns of secretion, initial and final phases of increasing and decreasing testosterone secretions, respectively, and may be implicated in the development of histological structures of the testes and spermatogenesis.

Sexing in guinea fowls (Numida meleagris).

Despite the potentials and contributions of guinea fowls to economic and social life in Ghana, accurate sex identification in these birds is still a major problem. Three hundred and sixty guinea fowls (180 birds per sex) were used in determining a more accurate and farmer friendly sexing technique. The sexing methods explored were vent, biometric, and molecular techniques. Vent sexing was accomplished by measuring phalli in 28 and 32-week-old birds, while biometric sexing involved the measurement of morphometric traits and data analyzed using discriminant function analysis. Molecular sexing was carried out by DNA extraction and subsequent PCR using the 2550F/2718R primer set. Females had a wider (P<0.05) pelvic inlet than male birds from first week of age until the end of the study, while the opposite was true for wattle length. However, wattle length differed (P<0.05) between both sexes after 4 weeks of age. Combining the biometric variables in a discriminant function, males could be distinguished from females with an accuracy of 94%. During molecular sexing, the P2/P8 primer set was not effective in sexing guinea fowls because it amplified a single band in both sexes and in the same manner. The sex of guinea fowls was properly determined using the primer set 2550F/2718R. Females produced 2 bands of 396 bp and 344 bp, while males only produced the larger band. Phallus size in the 2 sexes were distinguishable from 8 weeks of age, with males having longer and thicker (P<0.05) phalli than their female counterparts. Combining the 2 variables in a discriminate function, males and females could be distinguished with 98.3% accuracy. While the molecular method remains the most accurate sexing technique, the biometric method emerged as the most farmer friendly approach to sexing guinea fowls.