Poult. Sci.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Poult Sci 2006. 85:1550-1554
© 2006 Poultry Science Association
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Nestor, K. E.
Right arrow Articles by Velleman, S. G.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Nestor, K. E.
Right arrow Articles by Velleman, S. G.

GENETICS

Genetics of Growth and Reproduction in the Turkey. 16. Effect of Repeated Backcrossing of an Egg Line to a Commercial Sire Line1

K. E. Nestor, J. W. Anderson, R. A. Patterson and S. G. Velleman2

Department of Animal Sciences, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster 44691

2 Corresponding author: velleman.1{at}osu.edu


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
The turkey industry’s view of the relative economic importance of growth and egg production has changed rapidly, and genetic changes by selection within lines may not be rapid enough to meet the changing needs. The objective of the present study was to determine the feasibility of rapidly increasing the BW of dam lines by repeated backcrossing of a dam line (E) to a commercial sire line (B). The experimental E line was selected long-term for increased egg production and was used as the model for a turkey dam line. The B line was larger (more than 3-fold) in BW at 8, 16, and 20 wk of age, had wider breasts (approximately 1.8-fold) at 16 wk of age, and had lower egg production for 180 d (about 3-fold) than the E line. Based on additive genetic variation, males in the F1 generation of the B x E cross did not differ from expected in BW at any age, but females of this cross had BW less than expected at 16 and 20 wk of age. In the F1 generation, breast width of the cross did not differ from the expected value, but egg production for 180 d was greater than expected (126.6 vs.102.3 eggs/hen). After 3 generations of backcrossing, the backcrosses exhibited a gain in 20-wk BW of 12.5 and 8.8 kg, respectively, for males and females; a gain of 5.9 and 5.3 cm in breast width at 16 wk of age for males and females, respectively; and a loss of 74.1 eggs per hen over a 180-d production period. Based on the results of the current and a previous study, limited backcrossing of a dam line to a sire line may be an economically feasible method to greatly increase the BW of dam lines without unduly sacrificing egg production. For maximum gains per generation, backcrossing probably should be used for a maximum of 2 or 3 generations.

Key Words: turkey • egg production • body weight • breast width • backcrossing


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Commercial turkeys are usually produced by mating a sire line (or sire-line cross) selected for growth traits with a dam line (or dam-line cross) in which selection is balanced between growth and reproduction. With this system of mating, the growth of the offspring is usually between the parental means, and a greater number of offspring can be produced due to the reproductive capacity of the females utilized.

Nestor et al. (1967) summarized early estimates of heritability (h2) of BW at various ages in selected turkey populations and reported that the unweighted averages of these estimates were 0.40, 0.42, 0.43, and 0.36, respectively, for birds in the age groups 0 to 8, 9 to 16, 17 to 24, and greater than 24 wk of age. McCartney (1961) reported very large h2 estimates (0.61 to 0.68) for BW at various ages in a randombred control population when the estimates were based on a full-sib analysis. In the randombred control line and sublines of the randombred control line (E) selected for increased egg production, increased 8- or 24-wk BW, Nestor et al. (1967) reported that the h2 of BW at 8, 16, and 14 wk of age were greater than 0.28. The estimates were larger when estimated by full-sib analysis in a randombred control population than in the selected lines but not when the estimates were based on regression of offspring on the midparent values. Other h2 estimates (Abplanalp et al., 1963; McCartney et al., 1968; Nestor, 1977b, 1984; Nestor et al., 1996, 2000) of BW at various ages based on response to selection were also large. Nestor et al. (2000) reported the realized h2 of 16-wk BW was 0.31, 0.27, and 0.24, respectively, in generations 1 to 10, 11 to 20, and 21 to 30, suggesting that long-term selection might have decreased the additive genetic variation.

Most of the published estimates of the h2 of breast width, a measure of the amount of breast muscle, were relatively large but probably slightly smaller than those for BW. Nestor et al. (1967) reported that the average h2 estimates of breast width, measured around 24 wk of age, in the earlier literature was 0.30, but h2 estimates reported in their study at this age averaged only 0.12. The h2 of weight of the breast muscles at 16 wk of age was estimated to be 0.35 and 0.08, respectively, in males and females from a randombred control line (Havenstein et al., 1988), and these estimates did not change after adjustment for scaling effects (Toelle et al., 1990).

The reported h2 estimates of egg production of turkeys are also large. In the E line selected long-term for increased egg production, the realized h2 for 84-d egg production was 0.61 in the first 4 generations of selection (McCartney et al., 1968) and 0.33 in the first 7 generations of selection (Nestor, 1971a). Nestor (1972) also reported an h2 estimate of 0.29 for 180-d egg production in 7 lines of turkeys based on the regression of daughters on dams. In later generations of the E line, realized h2 estimates for egg production were 0.34 for 180-d egg production and 0.26 for 250-d egg production (Nestor et al., 1996).

Based on the h2 estimates of BW, breast width, breast meat, and egg production, selection should be effective in increasing these traits in pure lines. Nestor et al. (1969) reported that commercial turkey breeders had made substantial gains in BW and egg production but lesser gains in breast width from 1957 to 1966. In a recent comparison of a 1966 randombred control population with commercial turkeys from 3 major turkey breeders, Havenstein et al. (2004a, b) found that commercial turkey breeders had increased the weight of male turkeys by 186, 208, 227, and 241 g/yr, respectively, for birds killed at 112, 140, 168, and 196 d of age. Corresponding increases in weight of females were 164, 179, 186, and 205 g/yr. The increase in BW of the commercial turkeys was associated with increases of 4.5, 4.8, 5.8, and 6.3% in breast yield at 112, 140, 168, and 196 d of age. Egg production was not measured in the Havenstein et al. (2004a, b) studies.

The turkey industry’s view of the relative economic importance of growth and reproductive traits has changed, rapidly. For example, the increased demand for further processed turkey products requires heavier dam lines and changes in growth greater than could be achieved with traditional selection would be very beneficial to the industry. Repeated backcrossing of a dam line to a sire line is one method of rapidly increasing BW in a dam line and would be economically feasible, provided other traits of economic importance, such as body conformation and reproduction, are not seriously compromised and nonadditive genetic variation is not an important source of variation.

Although line crossing is a common commercial practice, there is little evidence of nonadditive genetic variation for either BW (Nestor, 1971b, 1985), breast conformation, or egg production (Nestor, 1985; Cahaner and Siegel, 1986), except in crosses of lines exhibiting extreme differences in BW or body conformation (Emmerson et al., 1991; Ye et al., 1997; Nestor and Anderson, 1998; Nestor et al., 2004). In crosses of 2 commercial sire (CS) lines and an experimental line (F) selected only for increased 16-wk BW, heterosis was observed for BW but not for breast width (Nestor et al., 2001a, 2005b), even though heterosis was observed for the weights of the breast muscle (Nestor et al., 2001b, 2005a). The CS and F lines had a different growth pattern and differed greatly in breast width, with the CS lines having better body conformation than the F line.

Nestor et al. (1997) repeatedly backcrossed the E line to the F line and to a CS line, and even though the results of the 2 backcrosses were slightly different, the results suggested that limited repeated backcrossing of a dam line to a sire line may be an economically feasible method to greatly increase the BW of dam lines without unduly sacrificing reproduction capacity. The purpose of the present study was to determine the influence of repeated backcrossing the E line to another CS line (B) different from the one used by Nestor et al. (1997) on growth and performance to determine if the results of Nestor et al. (1997) might apply to other possible crosses. Previous research indicated that the E line was not closely related to the B line, based on frequency of class II MHC haplotypes (Zhu et al., 1996) and DNA fingerprinting (Ye et al., 1998).


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Females of the E line, beginning in the 39th generation of selection, were backcrossed to the B CS line, and the backcrossing was continued for 2 additional generations. Details of selection methods and responses to selection in the E line were given by McCartney et al. (1968), Nestor (1971a, 1980), Anthony et al. (1991), and Nestor et al. (1996). The E line was reproduced by pairmating 72 sires and 72 dams (Nestor, 1977a) each generation. A randombred control line (RBC2) was maintained without selection by pairmating 36 sires and 36 dams.

A sample of the B line was obtained from a major international turkey breeder as unpedigreed eggs. The B line was reproduced in the first generation by selecting 15 females and 10 males with minimal selection pressure for increased 16-wk BW and increased breast width to try to maintain the pure lines at current performance levels. Approximately 50% of the males with the largest BW and breast width were selected, whereas no selection was practiced in females.

The B line was reproduced each generation by artificially mating 10 or 11 sires to 16 to 20 dams, with each sire being mated to 1 or 2 dams. A different male was assigned to each hen with each insemination. The B-line males used to reproduce the pure B line were then artificially mated to 19 E-line females to produce the F1 generation, 16 F1 females to produce the first backcross, and 19 backcross females to produce the second backcross generation, with each male being assigned to 1 or 2 females, and the males assigned to each female were changed with each insemination. The method of mating used to produce the pure B line and the backcrosses was designed to obtain as large a genetic base as possible.

Offspring were grown in confinement, with the sexes housed separately in different buildings. Birds were fed on a declining protein system based on the schedule for males (Naber and Touchburn, 1970), with periodic upgrades of the rations so that they met or exceeded the current standards by the NRC. Continuous lighting was provided from hatching to 6 wk of age, at which time the photoperiod was reduced to 12 h/d. At 16 wk of age, the photoperiod was further reduced to 10 h/d and remained at this level during the rest of the growing period.

The average number of offspring reared per generations was 92, 104, 224, and 671 for the B line, backcrosses, RBC2 line, and E line, respectively. Body weights were recorded at 8, 16, and 20 wk of age. Breast width was measured at 16 wk of age by a caliper at 6.35 cm of body depth, at a point approximately 3.18 cm from the anterior point of the keel.

After the growing period, females were housed in a windowless breeder house, and the length of the photoperiod was reduced to 6 h for 8 wk before stimulatory lighting (14 h/d at an intensity of 51 lx) at approximately 39 wk of age. Breeder hens were fed a ration containing 17.6% protein, 2.25% Ca, 0.64% available P, and 2,751 kcal of ME/kg of feed, beginning 1 wk before stimulatory lighting. Egg production was recorded for 180 d. Egg production was based on an average of 22, 18, 34, and 71 hens each generation for the B line, backcrosses, RBC2 line, and E line, respectively.

Statistical Analysis
Means and variances were calculated for each genetic group-generation subclass for reproduction traits and for each genetic group–generation sex subclass for growth traits. In the F1 generation of the cross of the E and B lines, the expected values for the offspring was the averages of the 2 parental lines. In subsequent generations of the backcross, the expected value of the backcross was the average of the sire line (in the current generation) and the previous generation backcross, because selection continued in the sire line, and a random sample of females from the backcrosses served as dams. Year-to-year variations were estimated by substracting the average value of the RBC2 line over the duration of the experiment from each yearly value of the RBC2 line. The values (except for breast width) of the parental lines and backcrosses were adjusted by the use of the yearly deviations of the RBC2 line. This correction was utilized to remove the influence of yearly variation. Changes in the backcrosses were expressed relative to the E line in the first generation and to the backcross the previous generation thereafter.

Two-sample t-tests (Devore and Peck, 1986) were used to determine whether the observed and expected values for the backcross differed. The denominator of the t statistic was given by


Formula

where {sigma}2p was the pooled variance and n1 and n2 were the number of individuals in populations 1 and 2, respectively. The pooled variance was estimated by


Formula

where {sigma}21 and {sigma}22 were the variances for populations 1 and 2, respectively.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
The B line was more than 3-fold larger than the E line at 8, 16, and 20 wk of age (average 3.15-fold for males and 3.37-fold for females; Table 1Go). The B line also had a 1.73- and 1.85-fold increases in breast width for males and females, respectively, relative to the E line. The E line laid 2.99-fold (135.7 vs. 45.3) more eggs per hen in a 180-d egg production period than the B line.


View this table:
[in this window]
[in a new window]
  		Table 1. Parental values in the first generation of the backcross of an experimental turkey line (E) selected long-term for increased egg production and a commercial sire line (B)
 
Based on the assumption of additive genetic variation, males in the F1 cross of the B-line males and E-line females did not differ from expected BW at 8, 16, or 20 wk of age, but females of this cross had BW less than expected at 16 and 20 wk of age (Table 2Go). Males had less-than-expected BW at 16 and 20 wk of age in the first backcross (generation 2), but there was no difference from expected BW in the second backcross (generation 3). For females, no difference from expected BW was observed in the first backcross, and 8-wk BW was more than expected in the second backcross. The breast width did not differ from expected in any generation.


View this table:
[in this window]
[in a new window]
  		Table 2. Observed and expected means of BW, breast width, and egg production for repeated backcrosses of an experimental turkey line selected long term for increased egg production and a commercial sire line
 
Egg production for 180 d was greater than expected in the F1 cross (126.6 vs. 102.3 eggs), but there was no difference from expected egg production in the first and second backcrosses.

In total for the 3 generations, a large gain in BW of the backcrosses was obtained relative to the E line at 20 wk of age (12.47 and 8.84 kg for males and females, respectively; Table 3Go). Breast width also exhibited a total gain of 5.9 and 5.3 cm for males and females, respectively, relative to the E line. The improvement in growth-related traits was associated with a total loss of 74.1 eggs per hen over a 180-d production period.


View this table:
[in this window]
[in a new window]
  		Table 3. Change in growth traits and egg production in repeated back-crosses of a turkey line (E) selected long-term for increased egg production and a commercial sire line
 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
The E line was selected as a dam-line model in the current study and a study by Nestor et al. (1997). The E line has greater egg production, smaller BW, and poorer body conformation than most commercial dam lines (unpublished data). In the current study and that of Nestor et al. (1997), the E line was repeatedly backcrossed to 3 large-body turkey lines, 2 CS lines, and an experimental turkey line selected long-term for increased 16-wk BW. Differences between expected BW based on additive genetic variation and observed values in the first generation of the backcrosses could be attributable to heterosis, sex linkage, maternal effects, or a combination of these. In the present study and the study of Nestor et al. (1997), the offspring in the F1 of backcrosses that had greater-than-expected egg production in the CS x E and B x E crosses and similar-to-expected egg production in the F x E backcross, had similar expected breast width in the F x E and B x E backcrosses and less-than-expected breast width in the CS x E backcross, and had BW (with 1 exception) less than or equal to the expected value in all 3 backcrosses. In the F x E backcross, egg production of the first backcross was greater than expected. The greater-than-expected egg production in the F1 generation was probably not due to heterosis, because egg production in the first backcross was similar to expected egg production. In all 3 backcrosses, gains in BW and breast width in successive generations of backcrossing was associated with losses in egg production, but the data in the current study and that of Nestor et al. (1997) suggest that back-crossing of a dam line to a sire line might be a feasible method of rapidly changing BW without undue sacrifice in egg production. At 100 eggs per hen, the relative economic value to 10 eggs per hen is 86 g in BW gain in a fully integrated turkey operation (Pasternak et al., 1986). At 80 eggs per hen, the relative economic value equivalent to 10 eggs per hen is 86 g in BW gain. However, the calculations of Pasternak et al. (1986) fail to consider reduced costs associated with the further processing of heavier birds. For maximum gains per generation, back-crossing should probably be used for a maximum of 2 or 3 generations and perhaps could be usefully repeated after practicing several generations of selection within the dam line.

The reduction in egg production due to selection for increased 16-wk BW in the F line was primarily the result of a decrease in the intensity of lay, as measured by average clutch (Nestor et al., 1996, 2000). The total days lost from broodiness did not change consistently over generations of selection in the F line (Nestor et al., 1996, 2000). Selection for increased egg production in the E line has virtually eliminated broodiness and greatly increased intensity of lay (Anthony et al., 1991; Nestor et al., 1996). Therefore, improvements in egg production of F1 crosses of the E line and large-bodied lines were likely due to improvements of intensity of lay and a reduction in broodiness.


   FOOTNOTES
 
1 Salaries and research support provided by state and federal funds appropriated to the Ohio Agricultural Research and Development Center, The Ohio State University. Back

Received for publication January 23, 2006. Accepted for publication April 15, 2006.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Abplanalp, H., F. X. Ogasawara, and V. S. Asmundson. 1963. Influence of selection for body weight at different ages on growth of turkeys. Br. Poult. Sci. 4:71–82.[Medline]

Anthony, N. B., D. A. Emmerson, and K. E. Nestor. 1991. Genetics of growth and reproduction in the turkey. 12. Results of long-term selection for increased 180-day egg production. Poult. Sci. 70:1314–1322.[ISI][Medline]

Cahaner, A., and P. B. Siegel. 1986. Evaluation of industry breeding programs for meat-type chickens and turkeys. Pages 337–346 in Proc. 3rd World Congr. Gene. Appl. Livestock Prod. Vol. 10. G. E. Dickerson and R. K. Johnson, ed. Univ. Nebraska, Lincoln.

Devore, J., and R. Peck. 1986. Statistics: The Exploration and Analysis of Data. West Publishing Co., New York, NY.

Emmerson, D. A., N. B. Anthony, and K. E. Nestor. 1991. Genetics of growth and reproduction in the turkey. 11. Evidence of nonadditive genetic variation. Poult. Sci. 70:1084–1091.[ISI][Medline]

Havenstein, G. B., P. R. Ferket, J. L. Grimes, M. A. Qureshi, and K. E. Nestor. 2004a. Page 112 in Performance of 1966 vs. 2003 turkeys when fed representative 1996 and 2003 turkey diets. Proc. World’s Poult. Congr., Istanbul, Turkey.

Havenstein, G. B., P. R. Ferket, J. L. Grimes, M. A. Qureshi, and K. E. Nestor. 2004b. Changes in the performance of turkeys —1966–2003. Proc. 17th Tech. Turkeys Conf. Macclesfield, Cheshire, UK.

Havenstein, G. B., V. D. Toelle, K. E. Nestor, and W. L. Bacon. 1988. Estimates of genetic parameters in turkeys. 2. Body weight and carcass characteristics. Poult. Sci. 67:1388–1399.[ISI][Medline]

McCartney, M. G. 1961. Heritability and genetic correlations of body weights of White Holland turkeys. Poult. Sci. 40:1694–1700.

McCartney, M. G., K. E. Nestor, and W. R. Harvey. 1968. Genetics of growth and reproduction in the turkey. 2. Selection for increased body weight and egg production. Poult. Sci. 47:981–990.[ISI][Medline]

Naber, E. C., and S. P. Touchburn. 1970. Ohio poultry rations. Ohio Coop. Extension Serv. Bull. 343. The Ohio State University, Columbus.

Nestor, K. E. 1971a. Genetics of growth and reproduction. 3. Further selection for increased egg production. Poult. Sci. 50:1672–1682.

Nestor, K. E. 1971b. Genetics of growth and reproduction in the turkey. 4. Strain crossing for improvement of growth and reproduction. Poult. Sci. 50:1683–1689.

Nestor, K. E. 1972. Broodiness, intensity of lay, and total egg production of turkeys. Poult. Sci. 51:86–92.

Nestor, K. E. 1977a. The use of a paired mating system for the maintenance of experimental populations of turkeys. Poult. Sci. 56:60–65.

Nestor, K. E. 1977b. Genetics of growth and reproduction in the turkey. 5. Selection for increased body weight alone and in combination with increased egg production. Poult. Sci. 56:337–347.

Nestor, K. E. 1980. Genetics of growth and reproduction in the turkey. 8. Influence of a management change on response to selection for increased egg production. Poult. Sci. 59:1961–1965.

Nestor, K. E. 1984. Genetics of growth and reproduction in the turkey. 9. Long-term selection for increased 16-week body weight. Poult. Sci. 63:2114–2122.[ISI][Medline]

Nestor, K. E. 1985. Egg production consequences of improving growth and efficiency in turkeys. Pages 73–83 in Poultry Genetics and Breeding. W. G. Hill, J. M. Manson, and D. Hewitt, ed. British Poultry Science Ltd, Longman Group, Harlow, UK.

Nestor, K. E., and J. W. Anderson. 1998. Effect of crossing a line selected for increased shank width with two commercial sire lines on performance and walking ability of turkeys. Poult. Sci. 77:1601–1607.[Abstract/Free Full Text]

Nestor, K. E., J. W. Anderson, D. Hartzler, and S. G. Velleman. 2005a. Genetic variation in pure lines and crosses of large-bodied turkeys. 4. Body shape and carcass traits. Poult. Sci. 84:1825–1834.[Abstract/Free Full Text]

Nestor, K. E., J. W. Anderson, and R. A. Patterson. 2000. Genetics of growth and reproduction in the turkey. 14. Changes in genetic parameters over thirty generations of selection for increased body weight. Poult. Sci. 79:445–452.[Abstract/Free Full Text]

Nestor, K. E., J. W. Anderson, R. A. Patterson, and S. G. Velleman. 2004. Genetic variation in body weight and egg production in an experimental line selected long-term for increased egg production, a commercial dam line, and reciprocal crosses between lines. Poult. Sci. 83:1055–1059.[Abstract/Free Full Text]

Nestor, K. E., J. W. Anderson, and S. G. Velleman. 2001a. Genetic variation in pure lines and crosses of large-bodied turkey lines. 1. Body weight, walking ability, and body measurements of live birds. Poult. Sci. 80:1087–1092.[Abstract/Free Full Text]

Nestor, K. E., J. W. Anderson, and S. G. Velleman. 2001b. Genetic variation in pure lines and crosses of large-bodied turkey lines. 2. Carcass traits and body shape. Poult. Sci. 80:1093–1104.[Abstract/Free Full Text]

Nestor, K. E., J. W. Anderson, and S. G. Velleman. 2005b. Genetic variation in pure lines and crosses of large-bodied turkey lines. 3. Growth-related measurements on live birds. Poult. Sci. 84:1341–1346.[Abstract/Free Full Text]

Nestor, K. E., M. G. McCartney, and N. Bachev. 1969. Relative contributions of genetics and environment to turkey improvement. Poult. Sci. 48:1944–194.[ISI][Medline]

Nestor, K. E., M. G. McCartney, and W. R. Harvey. 1967. Genetics of growth and reproduction in the turkey. 1. Genetic and non-genetic variation in body weight and body measurements. Poult. Sci. 46:1374–1384.[ISI][Medline]

Nestor, K. E., D. O. Noble, and D. A. Emmerson. 1997. Genetics of growth and reproduction in the turkey. 13. Effects of repeated backcrossing of an egg line to two sire lines. Poult. Sci. 76:227–235.[Abstract/Free Full Text]

Nestor, K. E., D. O. Noble, J. Zhu, and Y. Moritsu. 1996. Direct and correlated responses to long-term selection for increased body weight and egg production in turkeys. Poult. Sci. 75:1180–1191.[ISI][Medline]

Pasternak, H., B. A. Shalev, and H. Engel. 1986. Genetic–economic evaluation of traits in a turkey enterprise: The relative economic values. World’s Poult. Sci. J. 42:5–11.

Toelle, V. D., G. B. Havenstein, K. E. Nestor, and W. L. Bacon. 1990. Estimates of genetic parameters in turkeys. 3. Sexual dimorphism and its implications in selection procedures. Poult. Sci. 69:1634–1643.[ISI][Medline]

Ye, X., J. W. Anderson, D. O. Noble, J. Zhu, and K. E. Nestor. 1997. Influence of crossing a line selected for increased shank width and a commercial sire line on performance and walking ability of turkeys. Poult. Sci. 76:1327–1331.[Abstract/Free Full Text]

Ye, X., J. Zhu, S. G. Velleman, and K. E. Nestor. 1998. Genetic diversity of commercial turkey primary breeding lines as estimated by DNA fingerprinting. Poult. Sci. 77:802–807.[Abstract/Free Full Text]

Zhu, J., K. E. Nestor, and Y. Tang. 1996. Frequencies and genetic diversity of major histocompatibility complex class II haplotypes in commercial turkey lines. Poult. Sci. 75:954–958.[ISI][Medline]




This article has been cited by other articles:


Home page
 Poult. Sci.Home page
R. A. Renema, V. R. Sikur, F. E. Robinson, D. R. Korver, and M. J. Zuidhof
Effects of Nutrient Density and Age at Photostimulation on Carcass Traits and Reproductive Efficiency in Fast- and Slow-Feathering Turkey Hens
Poult. Sci., September 1, 2008; 87(9): 1897 - 1908.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Nestor, K. E.
Right arrow Articles by Velleman, S. G.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Nestor, K. E.
Right arrow Articles by Velleman, S. G.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS