Brief Summary of Minutes of Annual Meeting

The business meeting with an industry perspective provided by Don McIntyre (Hybrid Turkeys). Whereas increasing industry attendance and participation was acknowledged as a group goal, there is value in keeping the number of participants relatively small in order to foster participant interaction. Favorable remarks were made about the format and the value of maintaining an ordered, and yet informal meeting. Participants were encouraged to apply for grant applications through the USPEA. The remainder of the business meeting was chaired by David Froman. In spite of project approval, there were two outstanding issues that needed resolution. The first was addressing how S1020 meets national research priorities. This question was answered, in part, by the fact that many participants have active grants from the NRICGP, which by definition, defines national research priorities affecting agriculture. Another consideration was the fact that the S1020 group includes a majority of US scientists who conduct research with turkeys. The second issue pertained to integration of extension. Perhaps a broader goal would be commercial application rather than extension activities per se; for a number of S1020 hold US patents and have, to some extent, been involved with technology transfer. However, it must be remembered that the application of any technology is often constrained by regulatory, legal, or commercial interests beyond the control of either scientists or extension specialist. Dr. Cherry agreed to facilitate any outstanding editing of the project related to these issues. Clarification was sought pertaining to filing station reports. Each member who participates as a leader of an Agricultural Experiment Station project needs to file an AD-421 form through his or her Experiment Station. This effort eventually entails filing an individual termination report. Nonetheless, annual and termination reports must also be filed for the group. David Froman agreed to collect input from participants and then edit input for submission to NIMSS. The site for the 2006 annual meeting was discussed. Annual meetings were held on the West Coast for 2004 (Portland, OR) and 2005 (San Francisco, CA). Therefore, it was proposed to hold the next meeting in the East. Potential sites included coastal Georgia, Puerto Rico, or the US Virgin Islands. Doug Rhoads agreed to investigate Caribbean options. Should these prove to be too expensive, Jeanna Wilson agreed to investigate sites on the Georgia coast. A location was to be defined early in 2006 for the purpose of advance planning, in particular, inviting key R&D VPs or their representatives. David Froman volunteered to serve as Project Chair for 2006 in order to expedite and complete the transition from S285 to S1020. This proposal was so moved, seconded, and approved by acclimation. The meeting adjourned with a thanks to Jim Millam for organizing and hosting the meeting. Positive remarks were also made by Mark Mirando and Jerry Cherry about the quality of the meeting and the accomplishments of the group.

Countering a long-term decline in the fertility of meat-type chickens. This effort addressed two broad factors affecting reproductive success: gamete quality and behavior. In turn, the investigation of each factor warranted diverse experimental approaches. In the case of gamete quality, these included the search for: (1) a gene that compromises sperm viability prior to ejaculation (Arkansas and Oregon); (2) a vaccine against avian infectious bronchitis virus that does not compromise epididymal function (Illinois and Arkansas); and (3) the basis for phenotypic variation in sperm mobility, a primary determinant of male fertility (Oregon and Arkansas). Doug Rhoads led the effort directed at finding the gene that induces a condition in which males ejaculate large percentages of dead sperm. This condition is called sperm degeneration dysfunction (SDD) because premature sperm degeneration appears to be due to a dysfunction of the male reproductive tract. Whereas this problem was attributed to a single dominant gene after the completion of breeding experiments in the late 20th century, this gene has proven difficult to find. Pedigreed populations of chickens have been produced using replicate affected broiler breeder males as founding sires. Birds from these populations were used to map the trait to a 3 Mbp region of chromosome 7 in one family. The same trait was mapped to chromosome 1 in a different family. Future work will be aimed at refining the map and developing a genetic test for SDD, i.e. a test based upon DNA rather than sperm cell viability. Janice Bahr led the investigation of the interaction between vaccination against avian infectious bronchitis virus (AIBV) and epididymal function. Chickens are routinely vaccinated against AIBV to prevent disease. Unfortunately, one unwanted side effect in males is compromised epididymal function. Specifically, stones form within the excurrent ducts of the testis. This phenomenon is analogous to kidney stones within the urinary tract. Roosters were immunized with a killed virus in order to determine whether stone formation was dependent upon live virus particles entering and then replicating within ciliated epithelial cells (the type of cell this virus attacks regardless of location). However, time course of stone development was comparable to that of controls vaccinated with live, attenuated AIBV. Thus, an autoimmune condition may result in which anti-AIBV antibodies, sperm agglutination, and stone formation are related. In any event, immunization of commercial flocks with killed AIBV is not a solution. Whereas killed AIBV does induce a stong immune response, the deleterious side effect persists. David Froman led the investigation of mechanisms underlying phenotypic variation in sperm mobility. Previous work had established that mitochondrial function was pivotal to phenotypic expression. Thus, experiments were designed to identify the reason for compromised mitochondrial function in low mobility sperm, i.e. sperm that are viable  perhaps even motile  but nonetheless lack an ability to move against resistance at body temperature. A model was proposed that accounts for the phenotypic range observed in broiler breeders. Seminal plasma glutamate enabled calcium uptake via NMDA receptors prior to ejaculation. Excessive calcium uptake triggers formation of the mitochondrial permeability transition pore, a prelude to mitochondrial demise. Sperm mobility is lost in proportion to the size of the subpopulation in which the mitochondrial permeability transition pore has formed. The importance of sperm mobility to broiler breeder performance was corroborated by a comparative assessment of males within two modern meat strains and the Athens random bred meat strain (Georgia and Oregon State). This effort was led by Jeanna Wilson. It is noteworthy that the Athens random bred males approximate founder stock from the 1950s. As evidenced by the magnitude of sperm mobility measurements and proportions of males within strains characterized by poor sperm mobility, it appears that sperm mobility has been compromised as broiler breeders have been selected for fast, efficient growth. In summary, advances were made relative to genetic and environmental factors that affect sperm quality. Likewise, advances were made in understanding how behavior affects broiler breeder reproductive efficiency (Maryland and USDA Beltsville). This effort was led by Inma Estevez. Specifically, reduced male mating frequency was not a cause of reduced fertility, although as expected, mating frequency depended upon the level of male-male competition within the mating system and was plastically adjusted accordingly. Variation in sperm quality did not appear to be a significant factor. The reasons why high mating frequency and sperm quality were poor predictors of fertility remain unresolved. Nonetheless, results strongly support the hypothesis that low male reproductive success may be related to poor male mating efficiency. Thus, there is a distinction between attempted copulation (mating frequency) and successful copulation (mating effectiveness). Developing an adaptive, comprehensive understanding of turkey egg hatchability that can be applied by commercial hatcheries. Due to large number of eggs that pass through hatcheries, correlation studies are highly suited to elucidating key variables that affect embryonic development and successful hatching. Likewise, the properties of the eggshell itself afford limitations and therefore insight into how eggs should be handled. For example, transport of gases, e.g. oxygen, through the eggshell is affected by egg weight, eggshell conductance, and the duration of embryonic development. Theoretically, embryo livability can be improved by changing egg weight, the properties of the eggshell, or incubation period. Of these three variables, only incubation period can be controlled by an operator. And complications arise because functional egg characteristics vary among lines of turkey hens and between hens at different ages within a line under any given set of conditions. Nonetheless, an advance was made by proving embryonic cardiac function to be a critical and useful variable for correlation analyses. This effort was led by Vern Christensen (NCSU) working in conjunction with Paul Johnston (BYU). Discovering the basis for photorefractoriness in turkeys. This effort was performed by Jim Millam (UC Davis), John Proudman (ARS, Beltsville) and Tom Siopes (NCSU). Understanding the neuronal circuitry controlling photorefractoriness is important in developing means to reduce photorefractoriness. Research at UC Davis advanced the understanding of neural control of photorefractoriness by narrowing the possibilities as to where a photorefractory block occurs within the brain. Research at Beltsville tested the efficacy of lighting programs aimed at retarding the onset of photorefractoriness. Manipulation of the photoperiod to prolong egg production must be done prior to 8 weeks after photostimulation (increased daylength). Ironically, daylength programs the brain to begin and end reproduction. The programming that serves to end reproduction appears to occur between 9 and 12 weeks after photostimulation. Therefore, timely reduction in photoperiod may prolong lay. Research at NCSU assessed the potential of light intensity as a management tool for controlling photorefractoriness. The threshold light intensity for photorefractoriness seems to be higher than that for photoperiodic drive. Collectively, these results suggest that modulation of timing and intensity may serve to affect the brain in a desirable manner. Explaining the CNS integration that drives the hypothalamic-pituitary-gonadal axis. Avian reproduction is entrained by photoperiod. In other words, encephalic photoreceptors ultimately affect the secretion of gonadotropin releasing hormone (GnRH). Consequently, the location and structure of neuronal networks are critical pieces of information relative how reproduction is controlled by the brain (Arkansas, Minnesota, UC Davis) In addition, the flow of information within the hypothalamic-pituitary-gonadal axis is another key area of study. This includes gene transcription in addition to the interaction of either neurotransmitters or hormones and their receptors (Arkansas, Louisiana State, Penn State). Wayne Kuenzel led an effort related to encephalic photoreception. When electrolytic lesions were made in the circumventricular organ, the development of the reproductive system was attenuated relative to intact controls. This region of the forebrain is known to contain photoreceptors. Thus, greater definition was given to the region of the brain that initiates and regulates the effect of photoperiodicity in birds. Likewise, a study was completed in which GnRH neurons were mapped and counted. Seven nuclei were observed within the forebrain and diencephalon that contain these crucial neurons. In addition, six terminal fields were identified. A second accomplishment was demonstrating a cost effective means of inducing molt that does not compromise animal welfare. In addition to neurons that secrete GnRH, the CNS contains neurons that secrete gonadotropin-inhibiting hormone. Ramesh Ramachandran discovered that neurons containing GnIH are located exclusively in hypothalamic paraventricular nuclei. The density of these neurons was comparable between egg-type chickens that were either in or out of lay. However, real-time quantitative PCR revealed a significant increase in GnIH mRNA in the diencephalons when hens were out of lay. In related work, GnIH depressed LH secretion from pituitary cells cultured in vitro. Finally, cDNA encoding the chicken GnIH receptor was cloned from a chicken pituitary cDNA library. Sexually immature egg-type chickens were found to have more GnIH receptor mRNA in their pituitary glands when compared to laying hens. FSH, like LH, is a pituitary hormone that affects gonadal function. However, the role of FSH is less understood. John Kirbys lab advanced FSH biology by cloning and expressing of the FSH beta proximal promoter from the domestic fowl. Computer-based analysis of bases within this region revealed in excess of 50 common DNA binding motifs. Sequential deletion mutants were intiated for further characterization. Regulation of the hypothalamic-pituitary-gonadal axis historically has been viewed in terms of environmental factors or chemical agents (exogenous or endogenous) acting upon an individual animal. However, Dan Satterlee demonstrated that the hypothalamic-pituitary adrenal axis of a dam can affect the hypothalamic-pituitary-gonadal axis of her male offspring. The agent that passes from dam to offspring is the steroid hormone corticosterone. Lines of Japanese quail have been selected for either low stress (LS) or high stress (HS). Reproductive traits were evaluated for male offspring from control or corticosterone-treated hens in each line. Cloacal foam production is a classic secondary sexual characteristic that is androgen dependent. Foam production at 8 weeks of age was staggered as follows: LS control > LS corticosterone > HS control > HS corticosterone. Consequently, genetic selection and maternal corticosterone appear to affect the hypothalamic-pituitary-gonadal of progeny.

Bilcik, B., and I. Estévez. 2005. Impact of male-male competition and morphological traits on mating strategies and reproductive success in broiler breeders. Appl. Anim. Behav. Sci. 92:307-323. Bilcik, B., I. Estévez, and E. Russek-Cohen. 2005. Reproductive success of broiler breeders in natural mating systems: The effect of male-male competition, sperm quality, and morphological characteristics. Poult. Sci. 84:1453-1462. Froman, D. P., and A. J. Feltmann. 2005. Fowl (Gallus domesticus) sperm motility depends upon mitochondrial calcium cycling driven by extracellular sodium. Biol. Reprod. 72:97-101 Froman, D. P., and J. D. Kirby. 2005. Sperm mobility: Phenotype in roosters (Gallus domesticus) determined by mitochondrial function. Biol. Reprod. 72:562-567. Kang, S.W., A. Thayananuphat, I. Rozenboim, J. R. Millam, J. A. Proudman and M. E. El Halawani. 2005. Expression of hypothalamic GnRH-I mRNA in the female turkey at different reproductive states and following photostimulation. General and Comparative Endocrinology (In press.) Proudman, J. A., and T. Siopes. 2005. Thyroid hormone and prolactin profiles in male and female turkeys following photostimulation. Poult. Sci. 84:942-946. Rathiam, T., and W. J. Kuenzel. 2005. Attenuation of gonadal response to photostimulation following ablation of neurons in the lateral septal organ of chicks. Brain Res. Bull. 64:455-461. Scanes, G. G., S. Jeftinija, A. Glavaski-Joksimovic, J. A. Proudman, and C. Aramburo. 2005. The anterior pituitary gland: Lessons from livestock. Domestic Anim. Endocrinol. 29:23-33. Siopes, T. 2005 Spontaneous recovery of photosensitivity by turkey breeder hens given prolonged exposure to long day lengths. Poult. Sci. 84:1470-1476. Wilhelms, K. W., S. A. Cutter, J. A. Proudman, L. L. Anderson, and C. G. Scanes. Atrazine and the hypothalamo-pituitary-gonadal axis in sexually maturing precocial birds: Studies in male Japanese quail. Toxicological Sci. 86:152-160.