Natural mating in broiler breeders: present and future concerns

Impact of different ratios of single and double interspiking on reproductive performance, some body welfare, and blood parameters of broiler breeders

The purpose of this study was to investigate the effects of different levels of single and double interspiking on reproductive performance, some body welfare, and blood parameters of broiler breeder flock. The study was carried out on a total of 3840 female and 384 male (with average weight 4706.07 ± 307.9 g) Ross 308 broiler breeders having age between 28 to 59 weeks in a broiler breeder house (40°13'16.3″N, 28°48'19.8″E) of a private commercial poultry company. A single interspiking was applied at the age of 45 weeks, and a double interspiking was applied at the age of 53 weeks with the ratio 75, 50, and 25% of the males in the trial groups were changed. The age was affected fertility ratio, hatchability of total eggs, and hatchability of fertile eggs in the single and double interspiking groups (P < 0.0001). While the spiking ratio was affected hatchability of fertile eggs in the single interspiking group (P < 0.0001), it was affected the fertility ratio, hatchability of fertile eggs in the double interspiking group (P = 0.015 and P = 0.024). The spiking type was affected fertility ratio and hatchability of total eggs (P = 0.002 and P = 0.001). The age and spiking ratio interaction was affected fertility ratio, hatchability of total eggs, and hatchability of fertile eggs in the single (P < 0.0001, P < 0.0001, and P = 0.053; respectively), and double interspiking groups (P = 0.015, P = 0.009, and P = 0.008; respectively). The age and spiking ratio and age- and spiking-type interaction were not affected body feather score and vent score in single and double interspiking group (P > 0.05). The age, spiking ratio, and type were not affected blood heterophil, lymphocyte, and heterophil/lymphocyte (H/L) ratio in the single and double interspiking group (P > 0.05). In conclusion, spiking program can be applied to the flocks which have poor management conditions and/or have less fertility traits.

Effects of dietary L-carnitine on puberty indices in the young breeder rooster

The aim of current study was to investigate the effect of dietary L-Carnitine (LC) in immature roosters on reproductive hormones, lipid profile and testicular histology at the time of maturity. Eighteen 12-wk-old breeder roosters (Ross 308) of similar weights were randomly allocated into 3 dietary treatments (LC-0: basic diet, LC-250: basic diet + 250 mg LC/kg of diet, LC-500: basic diet + 500 mg of LC/kg of diet) in 6 replicates. The feeding program and photoperiod regimen were performed based on ROSS 308 management handbook. Dietary LC supplementation markedly improved testicle weight and testicle index (p < 0.05). Comb height was also affected by LC supplementation (p < 0.05). The testicle weight and index, comb height, and shank lengths improved linearly with increasing levels of dietary LC (p < 0.05). The LC-250 and LC-500 diets significantly improved the number of sertoli cells (NSC), height epithelium seminiferous tubules (HEST), seminiferous tubules diameter (STD), spermiogenesis index (SI) and tubular differentiation index (TDI) of rooster's testis tissue (p < 0.05). The number of seminiferous tubules (NST) was affected by of the amount of LC (p < 0.05). The roosters on the LC-250 mg/kg diet had longer HEST compared to roosters that received the LC-500 mg/kg diet (p < 0.05). Testicular histology parameters increased in a linear and quadratic manner in response to increasing levels of LC (p < 0.05). Dietary LC significantly increased (p < 0.05) plasma concentrations of testosterone, GnRH, LH, FSH and High-Density Lipoprotein (HDL), but reduced the plasma concentration of Low-Density Lipoprotein (LDL). However, no significant differences were observed between LC-250 and LC-500 groups in these parameters. Plasma testosterone, GnRH, LH, LDL and HDL were affected in a linear and quadratic manner in response to increasing levels of LC (p < 0.05). Similarly, FSH increased linearly with increasing dietary LC (p < 0.05). Thus, adding up to 250g of LC per kg of the rooster chicken can improve reproductive hormones, blood lipids and testicular histology parameters at the time of maturity.

Rearing system influences the testicular development, semen quality and spermatogenic cell apoptosis of layer roosters

The objective of this study was to compare the testicular development, semen quality, and spermatogenic cell apoptosis of roosters reared in colony, single, and large cages. Rohman parental layers (n = 540) were randomly allocated into cages of rearing system groups (135 males and 405 females). The experimental period was 70 to 210 d of age. We compared testicular development and plasma main reproductive hormones (Follicle-stimulating hormone; Luteinizing hormone; Testosterone; Estrogen2;) from d 70 to 210 of roosters among the three systems. In addition, routine semen quality indexes, apoptosis of testicular spermatogenic cells and sperm apoptosis of breeding roosters under three rearing systems on d 175 and d 210 were evaluated. Roosters during the growing period (from d 70 to 140) have rapid testis growth and increasing main reproductive hormones in plasma. At the peak of sexual maturity (d 210), in colony cage, the females have a positive effect and promote the testis development of males. However, the stocking density in colony cage has no effect on testicular development; compared with the single and large cage. Roosters reared in the natural mating system had better semen quality, particularly in semen volume, density, and viability; the hatching % of fertilized eggs and healthy chicks were higher for the colony than single and large cages. Furthermore, the sperm density was higher for colony than single and large cages, which was related to the apoptosis of spermatogonia and spermatocyte, not the apoptosis of mature sperm. This study provided the basic data for the reproductive performance research of chicken reared in the colony cages.

Influence of male-male competition on reproductive performance and mortality of broiler breeders following intra-spiking

The study was conducted to determine the influence of male-male competition on reproductive performance and male mortality of Cobb 500 broiler breeder flocks following double intra-spiking. Broiler breeders were housed in 3 open-sided houses each accommodating 8,200 females and 820 males. Males of the same age on the same farm were exchanged between the houses (intra-spiking) to stimulate competition thereby changing the social hierarchy of each house. Intra-spiking was performed by replacing 25, 35, and 45% of males between the houses at 40 and 48 weeks of age (WOA), respectively. Eggs were collected from 36 to 55 WOA, when egg fertility and male mortality were recorded. Data was analyzed using repeated measures techniques of SAS 9.4, modeling the covariance structure of the observed data. Male-male competition (intra-spiking), age and their interaction significantly (P < 0.05) influenced egg fertility, hatchability, and male mortality. Average fertility and hatchability were increased in the 45% intra-spiked flocks (P < 0.05) (95.89 and 85.83%) compared with the 35% (95.13 and 86.30%) and 25% (94.42 and 0.23%) intra-spiked flocks. Fertility and hatchability with the 45% double intra-spiked flocks was consistently higher (P < 0.05) over time than the other double intra-spiked flocks. Male mortality was lower (P < 0.05) in the 45% intra-spiked flock (0.23%) than in the 35% (0.40%) and 25% (0.44%) intra-spiked flocks. After double intra-spiking, the male mortality in the 25 and 35% double intra-spiked flocks significantly increased (P < 0.05), whereas that of 45% intra-spiked flocks remained relatively low. Male mortality in the 45% intra-spiked flocks was consistently low over time than other double intra-spike levels from 45 WOA until the end of the trial. Noteworthy, egg fertility and hatchability gradually decreased, and mortality increased with increasing flock age toward the end of the productive life cycle. High level of male-male competition (45%) showed great promise as a tool to slow down the decrease in egg fertility and hatchability, and reduce male mortality in aging broiler breeder flocks.

D-Aspartate amends reproductive performance of aged roosters by changing gene expression and testicular histology

Male broiler breeders (n = 32) of 55 weeks of age were administered four different doses of capsulated d-aspartate (DA; 0, 100, 200 or 300 mg kg−1 day−1, p.o. (DA0, DA100, DA200 and DA300 respectively)) for 12 successive weeks to assess reproductive performance, blood testosterone, testicular histology and transcript levels of steroidogenic acute regulatory protein (StAR), cholesterol side-chain cleavage enzyme (P450scc), androgen receptor (AR), LH receptor (LHR), 3β-hydroxysteroid dehydrogenase (3BHSD), proliferating cell nuclear antigen (PCNA), glutamate ionotropic receptor NMDA type subunit 1 (GRIN1) and glutamate ionotropic receptor NMDA type subunit 2B (GRIN2B). Blood samples and ejaculates were collected, and bodyweight was recorded weekly for 10 weeks. AI was performed weekly for the last 2 weeks to determine the number of sperm penetration holes in the perivitelline layer, fertility and hatchability. Testes histology and transcript levels were evaluated in the 12th week. Bodyweight, numbers of Leydig cells and blood vessels, testis index and levels of sperm abnormalities were not affected (P > 0.05) by the treatment. However, sperm total and forward motility, plasma membrane integrity and functionality of sperm, ejaculate volume, testosterone concentration and fertility were higher (P < 0.05) in both the DA200 and DA300 groups compared with the other groups. In the DA100 and DA200 groups, sperm concentration, number of spermatogonia, thickness of the seminiferous epithelium and the diameter of tubules were significantly higher (P < 0.05) than the other DA-treated groups. The number of penetration holes, hatchability and malondialdehyde concentration were higher in the DA200, all DA-treated and DA300 groups respectively compared with the control and other treatment groups. Except for P450scc, AR, LHR and PCNA transcript levels in the DA300 groups, the relative expression of the genes evaluated improved significantly in the other DA-treated groups. Based on these experimental findings, it is concluded that DA improves reproductive performance of aged roosters.

Chicken Is a Useful Model to Investigate the Role of Adipokines in Metabolic and Reproductive Diseases

Reproduction is a complex and essential physiological process required by all species to produce a new generation. This process involves strict hormonal regulation, depending on a connection between the hypothalamus-pituitary-gonadal axis and peripheral organs. Metabolic homeostasis influences the reproductive functions, and its alteration leads to disturbances in the reproductive functions of humans as well as animals. For a long time, adipose tissue has been recognised as an endocrine organ but its ability to secrete and release hormones called adipokines is now emerging. Adipokines have been found to play a major role in the regulation of metabolic and reproductive processes at both central and peripheral levels. Leptin was initially the first adipokine that has been described to be the most involved in the metabolism/reproduction interrelation in mammals. In avian species, the role of leptin is still under debate. Recently, three novel adipokines have been discovered: adiponectin (ADIPOQ, ACRP30), visfatin (NAMPT, PBEF), and chemerin (RARRES2, TIG2). However, their mode of action between mammalian and nonmammalian species is different due to the different reproductive and metabolic systems. Herein, we will provide an overview of the structure and function related to metabolic and reproductive mechanisms of the latter three adipokines with emphasis on avian species.

Inheritance of fertility in broiler chickens

BACKGROUND

The fertility of a chicken's egg is a trait which depends on both the hen that lays the egg and on her mate. It is also known that fertility of an individual changes over the laying period.

METHODS

Longitudinal models including both random genetic and permanent environmental effects of both the female and her male mate were used to model the proportion of fertile eggs in a pedigree broiler population over the ages 29-54 weeks.

RESULTS

Both the male and the female contribute to variation in fertility. Estimates of heritability of weekly records were typically 7% for female and 10% for male contributions to fertility. Repeatability estimates ranged from 24 to 33%, respectively. The estimated genetic variance remained almost constant for both sexes over the laying period and the genetic correlations between different ages were close to 1.0. The permanent environment components increased substantially towards the end of the analyzed period, and correlations between permanent environment effects at different ages declined with increasing age difference The heritability of mean fertility over the whole laying period was estimated at 13% for females and 17% for males. A small positive correlation between genetic effects for male and female fertility was found.

CONCLUSION

Opportunities to improve fertility in broiler stocks by selection on both sexes exist and should have an impact throughout the laying period.