Progress 10/01/04 to 09/30/09
Outputs
OUTPUTS: Inheritance of embryo thyroid function was determined for selected lines of turkeys. Lines were examined that were selected from closed control randombred populations for increased egg production (E) or BW (F). Reciprocal crosses of dams and sires from selected lines and their randombred control lines (RBC1 or RBC2, respectively) were made to determine dam and sire effects. Crossing the RBC1 sire and E dam resulted in better embryo survival than all other crosses. Embryos from that cross survived pipping the shell and emerging from it better than did the other crosses. Reciprocal crosses of the F and RBC2 lines showed better embryo survival than did either pureline cross. Additionally, embryos survived pipping in the reciprocal better than in the pureline crosses. Thyroxine (T4) and triiodothyronine (T3) hormone concentrations differed among the crosses as well. Better embryo survival was associated with elevated T3:T4 ratios at internal and external pipping due primarily to
dams prior to pipping but due to sires at pipping. These effects were significant reciprocal (or sex-linked gene expression) orthogonal contrasts. Selection for increased egg production has reduced embryo heart weight and has altered the energy metabolism of the myocardium. The differences in energy metabolism may be due to the more rapid heart rates. Conversely, long-term selection for increased 16 week BW has significantly decreased the heart rate of F line embryos and has not changed the weight of the heart relative to the increased body weight until the embryo has passed through the plateau stage. The F line embryos show a different energy metabolism that relies much more on gluconeogenesis. Embryo deaths occur more frequently in turkey embryos when the energy metabolism of the myocardium shows elevated glycogen to lactate ratios as it did in the pure E and F lines. Poults from the lines were compared according to their hatch, 3-, 7-d body weight, jejunum weight, jejunum length,
and jejunal maltase and alkaline phosphatase activities. Orthogonal contrasts of the data from the pure line and reciprocal cross-poult data were used to estimate additive genetic effects, reciprocal effects (confounded maternal and sex-linked effects), and heterosis for each of the traits measured. Body weights at hatch and at 3 and 7 d of age were increased in the F line relative to the RBC2 line and were decreased in the E line relative to the RBC1 line. The genetic changes from long-term selection in the E and F lines have had concimitant effects on jejunum growth and function that parallel the changes in growth rate. The increased body weight of the F line poults and the decreased body weight of the E poults relative to their randombred controls may be due to increases in the absorption of nutrients because of greater intestinal mass rather than to differences in glucose digestion. Concomitant changes in egg weight in the 2 selected lines appear to have resulted in maternal
effects that have significantly affected neonatal body weight and digestive system maturation.
TARGET AUDIENCES: Geneticists, Physiologists, Commercial turkey producers
Impacts
These studies describe for the first time the modes of inheritance of physiological factors implicated in embryo survival. The predominant modes of inheritance were additive gene expression or heterosis indicating that embryo survival depends on genetic input from both sire and dam. Geneticists at primary breeding companies can now utilize this knowledge in their selection for breeding stock to be used in commercial turkey production. Knowing modes of inheritance will improve embryo and neonate livability.
Publications
- Christensen, V. L., L. G. Bagley, T. Olson, J. L. Grimes and D. T. Ort, 2006. Eggshell conductance of turkey eggs affects cardiac physiology and subsequent embryo survival. Int. J. of Poult. Sci. 5:1096-1101.
- Christensen, V. L., L. G. Bagley, T. Olson, J. L. Grimes, R. D. Rowland and D. T. Ort, 2006. Shell thickness of turkey eggs affects cardiac physiology and embryo survival. Int. J. of Poult. Sci. 5:796-803.
- Christensen, V. L., M. J. Wineland, D. T. Ort, K. M. Mann and E. R. Neely, 2006. Eggshell conductance and incubator humidity as factors in embryo survival and poult growth. Int. J. of Poult. Sci. 5:830-837.
|
Progress 10/01/05 to 09/30/06
Outputs
Inheritance of embryo thyroid function was measured in lines of turkeys. Two lines that had been selected for either increased egg production (E) or increased 16 wk BW (F) and their respective randombred controls (i.e., RBC1 and RBC2) were examined. Reciprocal crosses of dams and sires from each selected line and its randombred control were made to estimate sire line and dam line effects. Orthogonal contrasts were used to determine if the differences found were due to the presence of additive, non-additive, or maternal or sex-linked gene effects. With the data involved, sex-linkage and maternal effects could not be separated. Embryo survival was measured for all lines and their reciprocal crosses. Crossing the RBC1 sire and E dam also resulted in better embryo survival and lower death losses at pipping than for the other cross or purelines. Reciprocal crosses of the F and RBC2 lines showed better total embryo survival and they survived pipping better than the F or
RBC2 purelines. Thyroxine (T4) and triiodothyronine (T3) concentrations differed between the reciprocal crosses at external pipping, but the effects were inconsistent for the two data sets. Reciprocal tests indicated that sex-linked effects were present for T3 concentrations at internal pipping in the E and RBC1 lines, and at external pipping for the F and RBC2 lines. Reciprocal effects were significant for T4 at internal pipping for both data sets. The RBC1 sire embryos had significantly higher T3:T4 ratios the E line sire embryos at internal and external pipping, and the pureline RBC1 embryos had consistently higher ratios than did the pureline E embryos. The differences for the T3:T4 ratios between these two lines at internal pipping, external pipping, and hatch appeared to be consistently additive in nature, although significant non-additive or heterotic effects were present for the ratio at external pipping. Similar effects on the T3:T4 ratios were observed for the F and RBC2
lines at external pipping.
Impacts
The US public currently consumes nearly 100 pounds of poultry meat per year because it is healthy and an economical source of nutrients. Reproduction remains a major constraint to the production of commercial turkeys. Fertility and neonate survival cause significant financial losses for the industry. Hatchlings may also suffer metabolic diseases as a consequence of rapid growth. Identification of environmental and genetic factors that alter embryo muscle and cardiac function will improve survival rates and improve the economics of poultry production.
Publications
- Christensen, V. L., L. G. Bagley, T. Olson, J. L. Grimes, R. D. Rowland and D. T. Ort, 2006. Shell thickness of turkey eggs affects cardiac physiology and embryo survival. Int. J. of Poult. Sci. 5:796-803.
- Wineland, M. J., V. L. Christensen, I. Yildrum, B. D. Fairchild, D. T. Ort and K. M. Mann, 2006. Incubator environment interacts with genetic line of broiler at the plateau stage to affect embryo plasma thyroxine and triiodothyronine concentrations. Int. J. of Poult. Sci. 5:714-722
- Christensen, V. L., J. L. Grimes, R. D. Rowland and D. T. Ort, 2006. Effect of chelated calcium proteinate fed in the maternal diet of turkey breeders on embryo cardiac physiology. Int. J. of Poult. Sci. 5:337-343.
|
Progress 10/01/04 to 09/30/05
Outputs
Reciprocal crosses of selected lines of turkeys were examined to delineate the causes of embryo death and metabolic diseases in neonates. Studies in the current year focused on cardiac and muscle physiology. Crosses were made between selected lines and their randombred control lines to detect changes in genes resulting from the selection for increased body weight (F line) or egg production (E line). Genetic changes from long-term selection in the E and F lines have had concomitant effects in muscle growth and function that parallel the changes in growth rates. The increased BW of F line poults and the decreased BW of E line poults may be due to increases in individual muscles rather than differences in growth of all muscles and organs. Cardiac muscle has changed dramatically in body weight-selected embryos and neonates. Concomitant changes in egg weight in the two selected lines appear to have resulted in maternal effects that significantly affect neonatal muscle and
heart. Reduced egg size may be a major factor in contributing to reduced muscle weight, and is probably involved in the weak poults observed in the E line (Noble et al., 1999). However, the sire had a major contribution to the effects on cardiac growth and physiology in the F line. Concomitant changes in the length of the developmental periods of both selected lines may also play a role in the level of maturity at hatching (Christensen et al., 2001).
Impacts
The US public currently consumes nearly 100 pounds of poultry meat per year because it is healthy and an economical source of nutrients. Reproduction remains a major constraint to the production of commercial turkeys. Fertility and neonate survival cause significant financial losses for the industry. Hatchlings may also suffer metabolic diseases as a consequence of rapid growth. Identification of environmental and genetic factors that alter embryo muscle and cardiac function will improve survival rates and improve the economics of poultry production.
Publications
- Christensen, V. L., M. J. Wineland, D. T. Ort and K. M. Mann, 2005. Eggshell conductance and incubator ventilation as factors in embryo survival and poult quality. Int. J. Poult. Sci. 4:818-826.
- Christensen, V. L., M. J. Wineland, I. Yildrum, B. D. Fairchild, D. T. Ort and K. M. Mann, 2005. Incubator temperature and oxygen concentrations during the plateau stage in oxygen uptake affect turkey embryo plasma T4 and T3 concentrations. Int. J. Poult. Sci. 4:268-273.
- Suvarna, S., V. L. Christensen, D. T. Ort and W. J. Croom, Jr., 2005. High levels of dietary carbohydrate increase glucose transport in poult intestine. Comp. Bioche. Physiol. 141A:257-263.
|
Progress 10/01/03 to 09/30/04
Outputs
Thyroid hormones perform both functional and developmental roles in the growth and maturation of turkey embryos. The plasma concentrations of thyroxine and triiodothyronine have also been implicated in embryo viability as well. Studies performed indicate that the permeability of the eggshell may be a determinant of the concentrations of thyroid hormones in the embryonic turkey. Thus, one way a dam may affect the maturity of its offspring at hatching would be by the size and function of the eggshell that is created to enclose the developing embryo. Specifically, eggs with depressed eggshell conductance and eggshell conductance constants also displayed depressed embryonic plasma thryoid hormone concentrations. Eggs with depressed conductance also showed poor embryo survival and growth of the progeny was depressed. Paternal influences are more difficult to understand, but experiments showed clearly that sires selected for reproductive traits influence embryonic thyroid
output by depressing triiodothyronine concentrations whereas sires selected for increased body weight enhance the concentrations. It was concluded that the maturational changes in embryo thyroid that determine embryo viability are influenced by a complex interaction of sires and dams.
Impacts
Nearly 25% of all turkey eggs set in the US fail to hatch because of embryonic death. A 1% improvement in hatchability is worth nearly $15 million to the industry as hatched poults but much more as opportunity costs of lost production. Discovering proper environmental incubator conditions for improving embryo livability can provide great economic benefits.
Publications
- Christensen, V. L., M. J. Wineland, I. Yildrum, D. T. Ort and K. M Mann, 2004. Incubator temperature and oxygen concentration at the plateau stage affects cardiac health of turkey embryos. J. Anim. and Vet. Advances 3:52-65.
- Christensen, V. L., M. J. Wineland, I. Yildrum, D. T. Ort and K. M Mann, 2004. Incubator temperature and oxygen concentration at the plateau stage affects intestinal maturation of turkey embryos. Int. J. Poult. Sci. 3:378-385.
- Christensen, V. L., D. T. Ort, M. J. Wineland, and J. L. Grimes, 2004. Turkey sire effects on embryonic survival and physiology. Int. J. Poult. Sci. 3:80-88
- Christensen, V. L., and G. S. Davis, 2004. Maternal dietary iodide influences turkey embryo thyroid function. Int. J. Poult Sci. 3:550-557.
- Suvarna, S., V. L. Christensen, D. T. Ort and W. J. Croom, 2004. Ontogeny of intestinal glucose transport in heavy and light body weight turkey poults. Int. J. Poult. Sci. 3:783-790.
|
Progress 01/01/03 to 12/31/03
Outputs
The physiological role of humidity in the incubation of turkey eggs is only partially understood. The role that overhydration plays in embryonic survival is not easily understood. Experience has proven that a relative humidity (RH) of 54% inside the incubation cabinet is ideal for embryonic survival. However, incubator humidity still must be increased during the final days of embryonic development to prevent embryos from dying. Experiments examining the effects of high humidity in incubator cabinets have been conducted over the past several years. The trials were conducted comparing 75% RH to the standard 54%. When humidity and eggshell permeability were the factors in the experiment, both factors depressed embryonic livability, but they did not interact. High RH with low eggshell conductance seemed to have additive effects on depressing embryonic livability. Data indicated that when oxygen concentrations in the incubator cabinets and eggshell conductance were kept
constant, then High RH had a direct effect on the survival of turkey embryos. The time at which embryos were exposed to High RH was tested, and turkey embryos exhibited greater sensitivity to High RH prior to day 14 of development and to Low RH later than 14 days of development. It is recommended that humidity greater than 54% be avoided during the initial stages of incubation and that humidity less than 75% be avoided later in development.
Impacts
Nearly 25% of all turkey eggs set in the US fail to hatch because of embryonic death. A 1% improvement in hatchability is worth nearly $15 million to the industry as hatched poults but much more as opportunity costs of lost production. Discovering proper environmental incubator conditions for improving embryo livability can provide great economic benefits.
Publications
- Christensen, V. L., D. T. Ort and J. L. Grimes, 2003. Relationship of the eggshell conductance constant to neonatal cardiac physiology. Int. J. of Poult. Sci. 2:220-228.
- Christensen, V. L., D. T. Ort, M. J. Wineland and Jesse L. Grimes, 2004. Turkey sire effects on embryonic survival and physiology. Int. J. of Poult. Sci. 3:80-88.
- Christensen, V. L., J. L. Grimes, M. J. Wineland and G. S. Davis, 2003. Accelerating embryonic growth during incubation following prolonged egg storage 1. Embryonic livability. Poult. Sci. 82:1863-1868.
- Christensen, V. L., J. L. Grimes, M. J. Wineland and G. S. Davis, 2003. Accelerating embryonic growth during incubation following prolonged egg storage 2. Embryonic growth and metabolism. Poult. Sci. 82:1869-1878.
|
Progress 10/01/01 to 09/30/02
Outputs
Lines of turkeys known to have different embryonic growth and survival were examined. The eggs differed in weight, eggshell conductance, hatchling weight and organ maturity at the time of hatching. Eggs were produced through a 20 week laying period and embryos were sampled at monthly intervals. Half of the hens producing eggs were fed additional iodide in their diets, then, subsequently half were incubated at either 36.8 or 37.5 C to prolong the developmental period. Embryos were sampled during the final week of development and thyroid hormones were measured. Line, diet and incubation period interacted to affect the levels of thyroxine, triiodothyronine and their ratio. It was concluded that envronmental factors interact with maternal factors to affect circulating levels of thyroid hormones in turkey embryos.
Impacts
Environmental factors affecting circulating thyroid hormones can be manipulated in turkey embryos to effect changes in metabolic functions and growth. Changes in metabolism may subsequently meet the metabolic needs of the embryo and improve turkey egg hatchability.
Publications
- Fairchild, B. D., and V. L. Christensen, 2002. The effects of hen age, strain, on sperm penetration of the inner perivitelline layer and the relationship to embryonic mortality. Poultry Sci. 80(Suppl. 1):46.
- Christensen, V. L., G. S. Davis, and K. E. Nestor, 2002. Environmental incubation factors influence embryonic thyroid hormones. Poultry Sci. 81:442-450.
- Christensen, V. L., B. D. Fairchild, and K. E. Nestor, 2002. Sire and dam effects on fertility, inner perivitelline membrane sperm binding and embryonic survival of turkeys selected for increased egg production or body weight. Poultry Sci. 80(Suppl. 1):47
|
Progress 10/01/00 to 09/30/01
Outputs
Embryonic survival is notoriously poor among turkeys. As birds are selected for rapid growth, embryonic livability declines. The causes of the decline are not known. The hypothesis was proposed that pathological polyspermy might be responsible for embryonic deaths occurring very early in the developmental period. We examined sperm binding to the egg perivitelline membrane and subsequent embryonic survival rates of lines of turkeys selected for rapid growth or increased egg production, traits know to be negatively correlated. Reciprocal crosses were made with each line using its randombred control line to determine the changes that may have occurred in sires and dams following selection for greater than 30 generations. We noted clear sire and dam effects in sperm binding and sire by dam interactions for embryonic survival and frequency of early embryonic mortality following fertilization. The possibility exists that excessive binding to the perivitelline membrane
allows penetration of a large population of spermatozoa into the female germplasm. This population may include spermatozoa that are weakened or defective resulting in early embryonic mortality because of a pathological polyspermy.
Impacts
Successful hatching among commercial turkey breeder flocks occurs approximately 75% of the time. Losses due to embryonic deaths total in millions of dollars per day. A 1% increase in hatchability among turkey eggs in the US is worth approximately $3 million. Discovering techniques that allow us to control the binding of spermatozoa to the perivitelline membrane can improve embryonic survival resulting in improved profitability for turkey breeders as well as reduce the cost of turkey to the consumer.
Publications
- Fasenko, G. M., V. L. Christensen, M. J. Wineland, and J. N. Petitte, 2001. Examining the effects of prestorage incubation of turkey breeder eggs on embryonic development and hatchability of eggs stored for four or fourteen days. Poultry Science 80:132-138.
- Christensen, V. L., J. L. Grimes, and M. J. Wineland, 2001. Effects of turkey breeder hen age, and length of the incubation period on survival of embryos and hatchlings. J. Appl. Poultry Research 10:5-15.
- Fairchild, B. D., and V. L. Christensen, 2001. Differences in in vitro sperm hydrolysis of the perivitelline layer between two commercial lines of hens. J. Anim. Sci. 79 (Suppl. 1):173.
|
Progress 10/01/99 to 09/30/00
Outputs
Sperm binding to the inner perivitelline membrane was tested as a possible mechanism to explain embryonic mortality in turkeys. Lines of turkeys whose embryos die at different times during development were compared for sperm binding. Lines with increased early embryonic mortality had decreased abilities to bind spermatozoa compared to control lines. Lines with very little embryonic mortality possessed low levels of binding but did not differ from control lines. Treatments to sperm that have been shown to increase embryonic were used to damage spermatozoa of both lines prior to insemination. The line exhibiting increased mortality had different binding rates whereas that of the line with little mortality did not. It was concluded that proper sperm binding to the inner perivitelline membrane of turkeys eggs may be a mechanism to insure viability of embryos.
Impacts
Nearly 25% of all turkey eggs set in incubators in the US have embryos that die prior to hatching. Any improvement in embryonic survival can have major impacts on the economics of turkey production. Each 1% improvement nationally is worth almost $1 million to the commercial turkey industry.
Publications
- Fairchild, B. D., and V. L. Christensen, 2000. Photostimulation of turkey eggs accelerates hatching times without affecting hatchability, liver or heart growth, or glycogen content. Poultry Science 79;1627-1631.
- Fairchild, B. D., V. L. Christensen, and L. G. Bagley, 2000. The relationship of insemination sperm concentration and hen age on the number of holes hydrolyzed in the perivitelline membrane. Poultry Science 79:51 (Abstract).
|
Progress 10/01/98 to 09/30/99
Outputs
Incubation temperatures and eggshell conductances (the functional quality of an egg) were used to lengthen the incubation periods of developing turkey embryos. At hatching the baby turkey has a limited ability to digest and absorb carbohydrate. Delaying embryonic development approximately 24 hours resulted in greater intestinal maturity in hatchling poults when compared to controls. Increased intestinal maltase and alkaline phosphatase enzyme activities were seen at hatching and at 7 days post-hatching. Additionally, poults with more mature intestines grew faster for 7 days post-hatching.
Impacts
These studies will assist turkey growers identifying management factors that can improve hatchling survival and growth. Prolonging incubation periods can improve post-hatching growth and survival which are problems of great economic importance to the turkey industry.
Publications
- Christensen, V. L., W. E. Donaldson, and K. E. Nestor, 1999. Length of the plateau and pipping stages of incubation affects the physiology and survival of turkeys. British Poultry Science 40:297-303.
- Christensen, V. L., W. E. Donaldson, and K. E. Nestor, 1999. Effect of supplemental oxygen on blood plasma organic acids within embryos from selected lines of turkeys. Poultry Science 78:1602-1605.
- Christensen, V. L., J. P. McMurtry, W. E. Donaldson, and K. E. Nestor, 1999. Supplemental oxygen affects plasma insulin-like growth factors in embryos from selected lines of turkeys. Poultry Science 78:1606-1610.
|
Progress 01/01/98 to 12/31/98
Outputs
Embryonic growth of avian species is determined primarily by egg weight and the length of the incubation period. Previous reports indicated that the maternal thyroid can affect both egg weights and the length of the incubation period. Lines of turkeys with differing plasma concentrations of thyroid hormones were used in these studies. Eggs were produced by hens from each line but were incubated differently to shorten or lengthen the incubation period. Embryonic growth and carbohydrate metabolism were measured. Lines of hens with depressed thyroid output produced eggs whose embryos survived best at longer incubation periods but eggs from enhanced thyroid output hens survived best at shorter incubation periods. The data suggest that egg weight, eggshell conductance (factors determined by the hen) are interdependent with the length of the incubation period insofar as embryonic survival is concerned.
Impacts
(N/A)
Publications
- Temple, Louise M., Weiss, Alison A., Walker, Kimberly E., Barnes, H. John, Christensen, Vern L., Miyamoto, David M., Shelton, Celia B., and Orndorff, Paul E. 1998. Bordatella avium virulence measured in vivo and in vitro. Infection and Immunity 66:5244-5251.
- Fan, Y.K., Croom, W.J., Christensen, V.L., Bird, A.R., Daniel, L.R., McBride, B.W., and Eisen, E.J. 1998. Apparent energetic efficiency of jejunal glucose uptake in young adult turkeys selected for rapid growth. Canadian Journal of Anim. Sci. 78:301-306.
- Christensen, V.L., Donaldson, W.E., and Nestor, K.E. 1998. Relation of eggshell conductance constants and genetics to survival of turkey embryos. Poultry Sci. 77:78.
|
Progress 01/01/97 to 12/31/97
Outputs
The hypothesis was tested that T3 has a physiological role in the control of the length of incubation periods. Strains of turkey from the Ohio State University were utilized in these studies. The growth selected strain (F) was compared to its randombred control population (RBC2), and the egg production selected line (E) was compared to its randombred control population (RBC1). Breeder hens were randomly assigned to pens and fed one of two diets. The basal diet was a typical turkey breeder formulation, and the treatment diet contained 10 fold the level of iodine supplemented to the basal diet. The length of the incubation period was altered artificially by incubating half of the eggs from each treatment group at a lower temperature for the initial 25 days of incubation compared to control temperatures. Significant three way interactions for primarily T3 concentrations were observed at external pipping and in the hatched poults. The data suggested that genetics, diet,
and length of the incubation period are all factors that interact to ensure embryonic growth and survival and posthatch growth are not compromised.
Impacts
(N/A)
Publications
- FAN, Y.K., CROOM, J., CHRISTENSEN, V.L., BLACK, B.L., BIRD, A.R.,
- L.R., MCBRIDE, B.W. and EISEN, E.J. 1997. Jejunal glucose uptake and
- consumption in turkey poults selected for rapid growth. Poultry Sci.
- 1745.
- ---
- CHRISTENSEN, V.L., DONALDSON, W.E. and NESTOR, K.E. 1997. Effects of
- oxygen-enriched environment on the survival of turkey embryos between
- 28 days of age. Poultry Sci. 76:1556-1562.
- QUEEN, W.H., CHRISTENSEN, V.L. and MAY, J.D. 1997. Supplemental
- hormones and molting in turkey breeder hens. Poultry Sci. 76:887-893.
- ---
|
Progress 01/01/96 to 12/30/96
Outputs
The growth rate of turkey embryos was altered by lowering incubation temperatures by .15 C compared to controls at wk 1, 2, 3, or 4 of incubation. Growth differences were assessed by weighing embryos at the completion of 7, 14, and 21 d of incubation. Weights were further verified by measuring embryonic DNA and total protein. Growth at 24 to 28 d was additionally measured by weighing whole bodies, livers, hearts, and pipping muscles. Survival was assessed on 60,000 fertile eggs. Fertility and hatchability were evaluated following macroscopic examination of nonhatching eggs following incubation. Data were analyzed using the GLM procedure and orthogonal contrasts. Increasing temperature at wk 1 and 2 as well as at wk 3 and 4 affected growth and embryonic survival. Higher temperatures and faster growth rates during wk 1 and 2 of incubation improved embryonic survival whereas increased temperatures and faster growth rates at wk 3 and 4 of incubation depressed embryonic
survival. When treatments were compared that increased growth rates at wk 1 and 2 as well as decreased growth rates at wk 3 and 4 were compared to their converse treatments, hatchability of fertile eggs increased. In general, faster growth early in development and slower growth rate late in development seem to aid embryonic survival of turkeys.
Impacts
(N/A)
Publications
- CHRISTENSEN, V. L., DAVIS, G.S. and LUCORE, L.A. 1996. Conductance and other functional qualities of ostrich eggs. Poultry Sci. 75:1404-1410.
- FASENKO, G.M. 1996. Factors influencing embryo and poult viability and growth in stored turkeyegg.
|
Progress 01/01/95 to 12/30/95
Outputs
A population of commercial breeding turkeys was subjected to DNA fingerprinting analysis. Two genetic families were selected from 250 hens and 25 toms to correlate known DNA sequences with economically important phenotypic characteristics. Each family consisted of 22 hens and one sire that were selected based on Southern Blot analysis. The hens were selected based on maximum band sharing whereas the single sire was selected based on minimal band sharing with the hens. The birds were tested through two generations by measuring economically important traits. A highly significant (P<.0001) positive correlation was found with blood glucose concentration at hatching, body weight at hatching and growth rate following hatching with a DNA sequence. The same DNA sequence was also highly (P<.0001) negatively correlated with reproductive traits. The most notable traits with negative correlations were egg weight and eggshell conductance constants. The identified DNA
sequence may be involved in the negative correlation between growth and reproduction in animals.
Impacts
(N/A)
Publications
- CHRISTENSEN, V.L., HAVENSTEIN, G.B. and DAVIS, G.S. 1995. Egg characteristics, carbohydrate metabolism, and thyroid hormones in late chick embryos from different genetic lines. Poultry Sci. 74:551-562.
- CHRISTENSEN, V.L., 1995. Factors affecting hatchability of turkey embryos. Poultry and Avian Biology Reviews 6(1):71-82
- DONALDSON, W.E., CHRISTENSEN, V.L., GARLICH, J.D., MCMURTRY, J.P. and OLSON, N.C. 1995. Exposure to excessive carbon dioxide: a risk factor for early poult mortality. J. Appl. Poultry Res. 4:249-253.
|
Progress 01/01/94 to 12/30/94
Outputs
The well known negative correlation between growth and hatchability in turkey hens was studied. Data indicated that eggshell conductance of commercial hens does not change allometrically (conductance constants) with increases in egg weight. It was proposed that longer incubation periods may better foster embryonic development of modern-type embryos. Incubation periods were lengthened by lowering incubation temperatures .5 C. Poults incubated at lower temperatures hatched 24 hr later with heavier hearts and muscles compared to controls. Blood plasma glucose and heart glycogen concentrations were also elevated in embryos from longer incubation periods compared to controls. Hatchability varied considerably among trials but did not appear to be affected adversely by longer incubation periods compared to controls. Poult livability was improved in poults hatching later compared to controls.
Impacts
(N/A)
Publications
- CHRISTENSEN, V.L. and DONALDSON, W.E. 1994. Effects of maternal thyroid status on embryo physiology and hatchability of commercial turkey eggs. Poultry Sci. 73:236-244.
- DONALDSON, W.E. and CHRISTENSEN, V.L. 1994. Dietary carbohydrate effects on some plasma organic acids and aspects of glucose metabolism in turkey poults. Comp. Biochem. Physiol. 109A:423-430.
- DONALDSON, W.E., CHRISTENSEN, V.L., and FERKET, P.R. 1994. Administration of propionate to day-old turkeys. Poultry Sci. 73:1249-1253.
- GRIMES, J.L., ORT, J.F., and CHRISTENSEN, V.L. 1994. The effect of protein level during the prebreeder period on performance of Large White turkey breeder hens after an induced molt. Poultry Sci. 73:37-44.
|
Progress 01/01/93 to 12/30/93
Outputs
Maternal body weight of commercial turkey breeder hens has increased nearly 20% in the last five years. Concomitant with increased body weight has been a decline in egg production. Restricted feeding has been an effective means for improving egg production and fecundity of broiler chickens which became too heavy to reproduce efficiently. Current studies indicated that physically restricting body weights of prepubescent commercial turkey breeders may also be an effective means of improving their reproductive performance. Restrictions of 15, 30, or 45% of the weight of full-fed controls indicated that the most severe restriction increased the number of poults by 10 additional neonates per hen compared to full-fed controls. The improved performance was attributed to more settable eggs per hen as well as improved hatchability of fertile eggs. The data may suggest a new management tool to improve profitability of turkey breeder hens.
Impacts
(N/A)
Publications
- CHRISTENSEN, V.L., DONALDSON, W.E., MCMURTRY, J.P., and NESTOR, K.E. 1993. Maternal dietary iodine interacts with genetics of turkeys to alter embryonic plasma thyroid hormone concentrations. Poultry Sci. 72 (Suppl. 1):95. (abstract)
- MCCORKLE, F., CHRISTENSEN, V.L., and QURESHI, M. 1993. Effect of biogenic amines on leukocyte migration in turkey poults. Poultry Sci. 72 (Suppl. 1):121. (abstract).
- CHRISTENSEN, V.L., DONALDSON, W.E., and NESTOR, K.E. 1993. Embryonic viability and metabolism in turkey lines selected for egg production or growth. Poultry Sci. 72:829-838.
|
Progress 01/01/92 to 12/30/92
Outputs
Hatchability was improved by 8% compared to controls in a flock of commercial turkey breeder hens fed 4 ppm iodine in the breeder diet. The embryonic physiology involved in this improvement was investigated. Maternal dietary iodine increased embryonic blood thyroxine concentrations during internal and external pipping but decreased the thyroxine following hatching. The deiodination of thyroxine to triiodothyronine was also increased by the iodine treatment. During pipping more glycogen was observed in embryonic heart and muscle tissue of the iodine treatment than in controls. The data suggest that increased substrate concentration of iodine increased embryonic thyroid hormone synthesis. The increased thyroxine was subsequently able to increase the amounts of glycogen in tissues which are unable to anaerobically create glycogen through gluconeogenesis. Two important tissues that are involved in embryonic survival during hatching, the heart and pipping muscle, were shown
to respond to dietary iodine. Dietary iodine in turkey breeder diets may be a relatively simple means of improving hatchability.
Impacts
(N/A)
Publications
- DONALDSON, W.E., BREWER, C.E., FERKET, P.R. and CHRISTENSEN, V.L. 1992. Posthatch carbohydrate feeding and subsequent performance of turkey poults. Poultry Sci. 71:128-132.
- CHRISTENSEN, V.L. and DONALDSON, W.E. 1992. The importance of timely removal from the incubator of hatched poults from three commercial strains. Poultry Sci. 71:1823-1829.
- CHRISTENSEN, V.L. and NESTOR, K.E. 1992. Changes in functional qualities of turkey eggshells in strains selected for egg production or growth. Proceedings XIX World's Poultry Congress 3:111. (abstract)
- CHRISTENSEN, V.L., DONALDSON, W.E. and NESTOR, K.E. 1992. Effect of maternal blood concentrations of triiodothyronine on embryonic growth and metabolism of large white turkeys. Poultry Sci. 71 (Suppl. 1):24. (abstract).
|
Progress 01/01/91 to 12/30/91
Outputs
Commercial turkey breeder hens were fed high levels of dietary iodine or triiodothyronine to influence maternal thyroid hormones. The influence of maternal thyroid hormones on the hatchability of turkey eggs was observed. Dietary iodine improved the hatchability of fertile turkey eggs. The improvement could be attributed to fewer embryos dying late in the incubation period. Feeding triiodothyronine caused hens to decrease the maternal investment in each egg and caused decreased hatchling plasma glucose concentrations. The elevation may be attributed to increased gluconeogenesis measured in pipping embryos from triiodothyronine-fed dams. It may be concluded that the maternal thyroid metabolism of turkeys selected for growth decreases hatchability by determining the carbohydrate metabolism of poult embryos in late incubation.
Impacts
(N/A)
Publications
- DONALDSON, W.E. and CHRISTENSEN, V.L. 1991. Dietary carbohydrate metabolism in turkey poults. Comp. Biochem. Physiol. 98A:347-350.
- ROBEL, E.J. and CHRISTENSEN, V.L. 1991. Increasing hatchability of turkey eggs by injecting eggs with pyridoxine. Br. Poult. Sci. 32:509-513.
- BAGLEY, L.G. and CHRISTENSEN, V.L. 1991. Hatchability hematological indices and growth of turkey embryos incubated at high altitude with supplemented oxygen during the first and fourth weeks of incubation. Poultry Sci. 70:358-365.
|
Progress 10/01/89 to 12/30/90
Outputs
Different strains of turkeys were examined for their genetic influence on hatchability. Embryonic carbohydrate metabolism and growth were found to be different among commercial strains of turkeys. Embryos from the slower growing strains hatched better and relied more on gluconeogenesis and had a higher respiration rate during hatching than did the more rapidly growing strain. To further define the role of genetics in hatchability, embryos from strains of turkeys selected for growth and reproduction were examined and compared to embryos from randombred control populations. Selection for reproduction decreased hatchability, embryonic growth and carbohydrate metabolism, whereas selection for growth decreased hatchability and carbohydrate metabolism but increased growth. The data suggest a possible role for growth hormone in decreasing hatchability of turkey eggs.
Impacts
(N/A)
Publications
- CHRISTENSEN, V. L. and ORT, J. F. 1990. Influence of diet mediated maternal thyroid alterations on functional properties of turkey eggs. Poultry Sci. 69: 1576-1581.
- QUEEN, H. W. 1990. Effect of thyroid hormones on the molting cycle of turkey breeder hens. M.S. Thesis, North Carolina State University, Raleigh. 212p.
|
|