Can testosterone and corticosterone predict the rate of display of male sexual behaviour, development of secondary sexual characters and fertility potential in primary broiler breeders?

Optimization of Stocking Density in Chukar Partridge (A. chukar) Breeder Flocks

The present study was aimed to determine the most appropriate stocking density in breeding partridges by considering animal welfare. For this purpose, feed consumption, egg production and quality parameters, fertility, survival rate, feather condition score, cortisol and testosterone hormones were examined. A total of 552 breeding partridges with a ratio of 3 females to 1 male were used in the study and the groups were designed as 0.25 m2, 0.19 m2, 0.15 m2 and 0.11 m2 per partridge (4 groups and 3 replicates). Increasing the stocking density had no effect on feed consumption while it negatively affected egg production. Higher stocking density had a negative effect on the feather condition score which is similar to those for egg production. A parallel decrease in feed consumption and egg production was observed with the temperature increases according to the summer months. Stocking density had no effect on egg quality parameters, fertility rate, survival rate, testosterone and cortisol. In conclusion, a larger allowed space with 0.20 m2/bird or more benefits egg production and the welfare degree of chukar partridges.

Genital stones: Radiological, histopathological, ultrastructural, and molecular analysis in rooster

Epididymal lithiasis, characterized by the formation of stones in the epididymis, has been associated with a decline in fertility in roosters. This study aimed to investigate the reproductive performance, ultrastructural characteristics, and expression of aromatase cytochrome P450 (CYP19) and aquaporin 9 (AQP9) in aged broiler breeder roosters affected by epididymal lithiasis. X-ray analysis confirmed the presence of genital stones in both the epididymis and testicular tissue regions. While there was a significant decrease in sperm concentration in the affected roosters compared to non-affected roosters, no significant differences were observed in total and progressive sperm motility between the two groups. Furthermore, the affected roosters exhibited significant abnormalities in semen parameters, except for sperm concentration and morphology. Transmission electron microscopy (TEM) revealed the depletion and deciliation of ciliated cells in the distal efferent ductules of the epididymis in affected roosters. Additionally, the expression of CYP19 and AQP9 was found to be increased in the epididymal region of affected roosters. Notably, we report the presence of testicular stones for the first time in this study, in addition to epididymal stones. Considering the male reproductive tract lesions observed, we propose the term "genital stones" to describe these conditions. Moreover, our findings suggest that the overexpression of AQP9, which is associated with a high copy number of the CYP19 gene in the epididymal region of affected aged roosters, may contribute to the formation of genital stones by promoting increased reabsorption of fluids in the epididymis. The condensation of epididymal duct contents and reduction in the population of ciliated cells further impairs semen movement and can lead to the blockage of extra-testicular ducts, resulting in the low fertility syndrome observed in aged roosters.

EFFECT OF ANTIOXIDANT SUPPLEMENTATION IN DIETS OF ROOSTERS DURING THE POST-PEAK PHASE ON REPRODUCTION AND PRODUCTION CHARACTERISTICS OF OFFSPRING

Abstract This study aimed to evaluate the effects of antioxidant supplementation in diets of breeding roosters during the post-peak phase on reproduction characteristics and muscle performance of offspring in two similar breeder houses from a local company. Treatments consisted of a control diet and a diet supplemented with antioxidants (8 ppm canthaxanthin + 40 ppm lycopene + 150 ppm vitamin C). During the 66th week of age, eggs were incubated, and offspring were housed. Dietary supplementation of the blend of antioxidant resulted in higher (p<0.05) weights of testicles, crests, dewlaps, dewlap thickness, and number of perforations (53.35 x 25.30) in relation to non-supplemented roosters. There was no significant effect (p>0.05) of supplementation of the antioxidant blend on weight gain and breast weight and count and diameter of muscle fibers of offspring at 7 days of age. Feed conversion and weight gain from 14 to 35 days were better (p<0.05) in offspring from supplemented roosters. The supplementation of an antioxidant blend in roosters improved reproductive characteristics assessed and feed conversion and weight gain of offspring.

Effects of dietary soybean isoflavones (SI) on reproduction in the young breeder rooster

Soybean isoflavones (SIs) are phytoestrogens that competitive with estrogens in body. Although SIs play an important role in reproduction, their role in testicular development in roosters is unknown. This study was conducted to investigate the effect of SIs on testicular development and serum reproductive hormone profiles in young breeder roosters (70-133days old). Gene expression of steroidogenic acute regulatory protein (StAR), cholesterol side-chain cleavage enzyme (P450scc), and 3β-hydroxysteroid dehydrogenase (3β-HSD), which are related to testosterone synthesis, in rooster testis were also evaluated after treatment with different SI doses. Although SIs had no significant effect on body weight, 5mg/kg SIs significantly increased the testis index and serum levels of reproductive hormones (gonadotropin releasing hormone, follicle- stimulating hormone, luteinizing hormone, and testosterone).To further investigate whether SIs regulate hormone synthesis via StAR, p450scc, 3β-HSD, real time-PCR was performed to measure the mRNA levels of the corresponding genes. The results showed that 5mg/kg of SIs significantly increased StAR mRNA levels. However, there were no significant effects on p450scc or 3β-HSD mRNA levels. Moreover, the spermatogonial development and the number of germ cell layers were increased by treatment with 5mg/kg of SIs. These results suggest that SIs promote testicular growth by increasing reproductive hormone secretion, which is closely related to StAR expression, to positively regulate reproduction in young roosters.

Mating activity and sperm penetration assay in prediction of the reproduction potential of domestic goose ganders in a harem system

In a natural mating system, the sexual behavior of birds has an important role in fertility success. Non-competitive mating system provides special conditions to study gander-goose interactions. Behavioral and physiological data from a domestic geese breeding flock was used to determine interrelationships between mating activity (MA) parameters, sperm penetration assay (SPA), plasma testosterone (T) concentration, and fertility (F). Moreover, variation in the frequency of gander-goose interactions during the intensive breeding period and the diurnal rhythm (short day - 10L:14D) were evaluated. The 2-/3-year-old ganders (n=15) and 1-/3-year-old geese (1♂:4♀) were observed. On the basis of successful copulation (SCop), groups of ganders with low (33.3%), intermediate (40%), and high (26.7%) frequency were categorized. Frequency of SCop was greater in the morning than in the afternoon. For the entire breeding period, SPA results obtained for the low frequency group were less than for the intermediate group. Fertility success for ganders from both low and intermediate groups was similar. There was a lack of association between MA, plasma T concentration, and SPA results. However, SCop was positively correlated with fertility. It is recommended that SCop be considered as a prognostic parameter for monitoring of ganders' reproductive potential. It is recommended that the sexual behavior of ganders be evaluated before the 1200h of the day. The SCop with an average frequency of 0.4-0.8 times during the day light hours appears to be associated with fertility results that are satisfactory for geese husbandry. Additionally, the SPA may be considered for identification of ganders with poor reproductive potential to facilitate the decision of changes in harem social structure during the first half of the breeding season.

Effects of dietary omega-3/omega-6 fatty acid ratios on reproduction in the young breeder rooster

BACKGROUND

Polyunsaturated fatty acids (PUFAs) are necessary for the body's metabolism, growth and development. Although PUFAs play an important role in the regulation of reproduction, their role in testis development in the rooster is unknown. The present study was conducted to investigate the effects of omega-3/omega-6 (n-3/n-6, PUFAs) ratios on reproductive performance in young breeder roosters. Plasma levels of reproductive hormones, testis development, and reproductive hormone receptor and StAR mRNA expression were also assessed.

RESULTS

Although PUFAs (n-3/n-6: 1/4.15) had no significant effect on the testis index (P > 0.05), the spermatogonial development and germ cell layers were increased. Moreover, serum levels of hormones (GnRH, FSH, LH and T) on day 35 were also significantly increased by PUFAs (n-3/n-6: 1/4.15). To investigate whether PUFAs regulate the expression of hormone receptors and StAR, real time-PCR was used to measure GnRHR, FSHR, LHR and StAR mRNA levels. PUFAs significantly increased the mRNA levels of all of these genes.

CONCLUSIONS

These results indicate that PUFAs enhance the reproductive performance of young roosters by increasing hormone secretion and function, the latter by up-regulating receptor expression. These findings provide a sound basis for a balanced n-3/n-6 PUFA ratio being beneficial to young rooster reproduction.