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RESEARCH NOTES
Contrary to findings in the present study, McWade and Beasley (1966) frequently observed gross lesions in follicles between feather tracts. In other studies (Lapen, unpublished data) gross lesions have been observed between tracts, but only occasionally. REFERENCES
HATCHING EGG PRODUCTION INCREASED WITHOUT DECREASING 8-WEEK BODY WEIGHT IN BROILER CHICKENS R. G. JAAP AND A. G. KHAN Department of Poultry Science, The Ohio State University, 674 West Lane Avenue, Columbus, Ohio 43210 (Received for publication August 25, 1971) ABSTRACT About 30 percent of the pullets laying at the highest rate produced full sib progenies which were used as breeders each of two generations. A highly significant increase from 50.6 to 57.3 percent in rate of hatching egg production was obtained in a 20-week test period after two generations of selection during a six-week period when each generation of pullets was about six to eight months of age. Total egg production was increased from 53.2 to 59.4 percent. Although the percentage of double-yolked eggs was reduced one percent, the reduction was statistically significant (P < .05) only during the first 10 weeks of production. There was no change in the percentage of shell deficient eggs or in egg weight. Age at first egg may have been reduced slightly 137 ± 3 days versus 144 ± 7 days for the randombred control. Grouth rate to eight weeks of age did not decline. A small, statistically non-significant, increase was realized which was attributed to a non-intentional cumulated selection differential in the families chosen for their superior rate of egg production. POULTRY SCIENCE 51: 336-338,
Egg production in broiler-type chickens declines when growth rate to eight or nine
1972
weeks of age is increased by selective breeding (Jaap et al., 1962; Kinney and
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Beasley, J. N., L. T. Patterson and D. H. McWade, 1970. Transmission of Marek's disease by poultry house dust and chicken dander. Am. J. Vet. Res. 31:339-344. Calnek, B. W., and S. B. Hitchner, 1969. Localization of viral antigen in chickens infected with Marek's disease herpesvirus. J. Nat. Cancer Inst. 4 3 : 935-949. Csermely, H., 1936. A tyukleukosis borelvatosassirol (Skin changes in fowl leucosis). Allatorv. Lapok. 59: 279-280. (Original not seen. Abstract: Vet. Bull. 8: 94, 1938). Haider, S. A., R. F. Lapen and S. G. Kenzy, 1970. Use of feathers in a gel precipitation test for Marek's disease. Poultry Sci. 49: 1654-1657. Helmbolt, C. F., F. K. Wills and M. N. Frazier, 1963. Field observations of the pathology of skin leukosis in Gallus gallus. Avian Dis. 7: 402-411.
Kenzy, S. G., and B. R. Cho, 1969. Transmission of classical Marek's disease by affected and carrier birds. Avian Dis. 13 :211-214. King, D. D., and H. L. Chute, 1969. Correlation of gross and microscopic pathology of skin and nerve lesions from condemned broilers. Maine Agr. Exp. Sta. and Agr. Res. Ser., U.S.D.A. Bull. 672, Univ. of Maine. Lapen, R. F., R. C. Piper and S. G. Kenzy, 1970. Cutaneous changes associated with Marek's disease of chickens. J. Nat. Cancer Inst. 45: 941-950. Lapen, R. F., S. G. Kenzy, R. C. Piper and J. M. Sharma, 1971. Pathogenesis of cutaneous Marek's disease in chickens. J. Nat. Cancer Inst. 47: 389-399. Lucas, A. M., and P. R. Stettenheim, 1965. Avian anatomy, 1-59 In H. E. Biester and L. H. Schwarte (eds.), Diseases of Poultry, 5th ed. Iowa State College Press, Ames, Iowa. McWade, D. H., and J. N. Beasley, 1966. Dermal lesions in avian leukosis. Proc. U. S. Livestock Sanit. Assoc. 17:607-613. Pettingill, O. S., Jr., 1961. A Laboratory and Field Manual of Ornithology. 3rd ed. Burgess Publishing Co., Minneapolis, Minn. Purchase, H. G., 1970. Virus-specific immunofluorescent and precipitin antigens and cell-free virus in the tissues of birds infected with Marek's disease. Cancer Res. 30: 1898-1908.
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RESEAKCH NOTES
TABLE 1.—Egg production of AG2C during a 20-week lest period Deviation Percent
from controlj
AG2 Production rate: All eggs 59.4 Hatchingeggs 57.3
+6.2** +6.7**
Defective eggs: Double yolked Shell defects
—1.0 0
1.4 2.2
** Highly significant, P < .01.
During the egg production test period of 20 weeks conducted after two generations of selection, 104 pullets of the AG2C selected line housed in randomly assigned cages with 111 contemporary AG2 controls completed the test period. Egg production during the 20-week test period from 22 to 42 weeks of age for progeny of the second selected generation of AG2 are summarized in Table 1. The response to selection for rate of hatching egg production was a highly significant increase in both all eggs (6.2%) and those suitable for hatching (6.7%) during this 20-week test period. There was no change in egg weight. The percentage of double yolked eggs was one percent less than those from randombred control. This difference was not statistically significant, even though the decrease in double yolked eggs was significant (P < .05) during the first half of the test period. The percentage of shell deficient eggs did not differ from that of the control. Age at first egg may have been reduced slightly, 137 ± 3 days for AG2C versus 144 ± 7 days for AG2. The lack of a correlated decline in growth rate of AG2C was indicated by the data for eight-week body weight summarized in Table 2. The small, statistically non-significant, increase in eight-week weight of both sexes above those for the AG2 control might have been expected. There was an accumulated unintentional
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Shoffner, 1967; and Merrit et al, 1966). However the converse may not be true. Kinney and Shoffner (1967) selected for "short term" rate of egg production for four generations in a meat-type population. Neither rate of lay nor eight-week body weight changed significantly although regressions of base population and generation means on generations were positive, being 0.4 percent for egg production and 17 and 11 grams for males and females, respectively. Our limited results may be summarized as follows: A highly significant increase from SO.6 to 57.3 percent in rate of hatching egg production was obtained in a twenty-week test period after two generations of selection during a six-week period when such generation of pullets was six to eight months of age. Growth rate to eight weeks of age did not decline. Our experiment utilized a randombred control, AG2, formed by pooling the inheritance of A and AG (Dev et al., 1969). After two generations of random breeding, a sub-line, AG2C, of the randombred control was selected for an increase in number of hatching eggs produced during a six-week period as soon as the pullets reached reproductive age, beginning about six months after hatching. No feed restriction was practiced. Pullets were housed in individual cages beginning about 20 to 24 weeks of age. Paired matings were accomplished by artificial insemination of 47 to 50 females in each line. Occasionally two females were inseminated with semen from the same male. Full and half-sib matings were avoided. Otherwise matings were assigned at random in both populations. In the selected line, AG2C, full-sib families were retained as breeders from dams which produced the largest number of hatching eggs during the six-week reproduction period. Selection intensity was 14 out of 50 families in the first generation and 12 families out of 47 in the second.
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RESEARCH NOTES
TABLE 2.—Eight-week body weight for progeny of the second selected generation Body weight (gm.) Males Females
1658+12 1353 + 8
Deviation from control AG2 +40 +23
REFERENCES Dev, D. S., R. G. Jaap and W. R. Harvey, 1969. Results of selection for eight-week body weight in three broiler populations of chickens. Poultry Sci. 48: 1336-1348. Jaap, R. G., J. H. Smith and B. L. Goodman, 1962. A genetic analysis of growth and egg production in meat-type chickens. Poultry Sci. 41 : 1439-1446. Kinney, T. B., Jr., and R. N. Shoffner, 1967. Phenotypic and genetic responses to selection in a meat-type poultry population. Poultry Sci. 46 : 900-910. Merritt, E. S., M. Zawalsky and S. B. Glen, 1966. Direct and correlated responses to selection for 63-day body weight in chickens. Proc. 13th Worlds Poultry Congress, p. 86-91.
THE EFFECT OF RESTRICTIVE FEEDING PROGAMS DURING THE GROWING PERIOD ON TURKEY BREEDERS 1 R. A. VOITLE AND R. H. HARMS Department of Poultry Science, University of Florida, Gainesville, Florida 32601 (Received for publication August 30, 1971)
ABSTRACT Three hundred-sixty Marston Broad White females, hatched in late December, were equally divided among 18 pens and full fed a turkey starter from 0-10 weeks of age. Then -j of the birds was assigned to each of the following feeding regimes: control grower {ad libitum), low protein {ad libitum), or skip-a-day (75 percent of control). All birds remained on these treatments to 24 weeks of age when the control group was placed on a commercial type breeder diet; however, at 14 weeks of age 40 birds from each treatment group were transferred to cages. All birds were fed a commercial type breeder diet, ad libitum, from 206 days. Feed consumption and body weights were the greatest in the control group, followed by the skip-a-day group, with the low protein group consuming the least feed and having the lightest body weights. Age at sexual maturity was earliest for the controls, followed by the skip-a-day group, with the low protein birds being delayed the longest. These differences were significant at the 0.05 level of probability. POULTRY SCIENCE 51: 338-340,
It is generally agreed that it is desirable to delay sexual maturity in turkey breeder hens. Atkinson et al. (1969) indicated that the only commercially accepted method for delaying sexual maturity is light restriction during the growing period. Wilson et al. (1967) reviewed the literature pertaining 1
Florida Agr. Exp. Sta. Journal Series No. 4060.
1972
to light restriction during the growing period and reported that it was necessary to delay sexual maturity for off-season egg production. Leighton (1970) stated that in order to avoid a high incidence of non-layers and small eggs, stimulatory lighting programs should not be initiated before 30 weeks of age with small type turkeys and 32 weeks of age for the larger types. Drugs
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selection differential for eight-week weight in both sexes of +113 grams for AG2C versus —12 grams for the randombred control. Realized heritability was .28 in AG2C and similar to that of the base populations A and AG (Dev et al., 1969). The rate of hatching egg production over a 20-week period was increased from SO.6 to 57.3% in two generations of selection
without decreasing body growth rate to eight weeks of age.