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The Influence of Divergent Growth Selection on Semen Traits, Fertility and Hatchability
T H E I N F L U E N C E OF D I V E R G E N T GROWTH SELECTION O N S E M E N TRAITS, FERTILITY A N D H A T C H A B I L I T Y K.
M.
C H E N G 1 AND B . L.
GOODMAN
Animal Industries Department, Southern Illinois University, Carbondale, Illinois 62901 (Received for publication August 20, 1975)
ABSTRACT The effects of divergent growth selection for 18 generations on semen characteristics, fertility and hatchability were investigated. Males from the low weight line produced semen with a significantly (P < 0.05) higher sperm concentration and a highly significantly (P £ 0.01) lower methylene blue reduction time than the males from the high line. Differences between lines for semen volume, sperm motility, percent of live sperm, fertility and hatchability were not statistically significant. POULTRY SCIENCE 55: 457-459, 1976
IVERGENT selection for body weight in chickens have resulted in differences in size as well as other traits including semen characteristics (Siegel, 1963; Marini and Goodman, 1969; Edens et al, 1973). The purpose of this paper is to explore the influence of divergent growth selection on semen traits and the subsequent effect on fertility and hatchability. MATERIALS AND METHODS The lines (high and low) used in this study were the result of selection for growth rate in diverse directions for 18 generations (Maloney et al., 1967; and Marini and Goodman, 1969). Semen volume, sperm motility, concentration, methylene blue reduction time, and percent of live sperm were studied on three semen samples from each of 40 males from each line. The laboratory procedures for determining quality and quantity of semen were described by Marini and Goodman (1969). Semen from each male was used to inseminate five females. White Leghorn and randombred White Rock (Athens-Canadian) females were used to equally express the effects of egg size and egg weight (Landauer, 1961) and the possible adverse female effects
1. Present address: Department of Animal Science, University of Minnesota, St. Paul, Minnesota 55101.
457
on fertility in growth selected line (Edens et al., 1973). Hens were inseminated with 0.05 cc. semen on the first, second, eighth and ninth day of the trial. Eggs were pedigreed the second day after the first insemination and was continued for 14 days. An additional two-week period was used to allow the elapse of fertility prior to inseminating females with semen from other males. Females inseminated with semen from the high line during one trial were used to inseminate with semen from the low line males during the next trial to balance the possible variation due to dams on fertility and hatchability. Eggs were candled and the fertile ones transferred on the 19th day of incubation. The apparent infertiles were broken to determine early embryonic death macroscopically. Fertility, hatchability of fertile and total eggs, and live sperm were measured in percent and then adjusted by the arcsin transformation. All data were analyzed by analysis of variance technique as outlined by Snedecor and Cochran (1967). RESULTS AND DISCUSSION The average values for each line, difference between lines and level of significance for semen traits, fertility and hatchability data are given in Table 1. Concentration of sperm was significantly greater (P < 0.05) in the low line as compared to the concentration in the high line (approximation 3.4 vs. 2.9
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on June 26, 2015
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458
REAEARCH NOTES
TABLE 1.—Average values and differences between lines for semen characteristics, fertility and hatchability Lines Traits Volume (cc.) MBRT (minutes) Concentration (mm. 3 ) Motility Live sperm (%) Fertility (%) Hatch fertile (%) Hatch total (%) * = P < 0.05. ** = P < 0.01.
High 0.39 42.00 2,882,910.00 2.17 97.00 54.00 90.10 55.80
Differences (High-Low) 0.02 13.50** -531,530.00* -0.31 -0.10 -9.60 2.60 -6.50
to ensure high fertility was met. In addition to the first insemination, birds were also inseminated on the second, eighth and ninth day. The low fertility was likely, in part, due to the age of the birds plus the high environmental temperature during the experiment. McCartney (1956) reported a highly significant correlation between duration of fertility and fertility. Duration of fertility data in the high and low lines were erratic; however, it would appear that fertility from the low line males increased more rapidly after insemination and was maintained at a slightly higher level than was the fertility from the high line males. Additional work is needed to determine if the significant diffferences in various semen traits are sufficiently great to significantly influence fertility and hatchability. REFERENCES Edens, F. W., H. P. Van Krey and P. B. Siegel, 1973. Selection for body weight at eight weeks of age. 10. Spermatozoal morphology. Poultry Sci. 52: 2287-2289. Landauer, W., 1961. The hatchability of chicken eggs as influenced by environment and heredity. Connecticut (Storrs) Agri. Expt. Sta. Mono. 1. Maloney, M. A., J. C. Gilbreath, J. F. Tierce and R. D. Morrison, 1967. Divergent selection for twelve-week body weight in the domestic fowl. Poultry Sci. 46: 1116-1127. Marini, P. J., and B. L. Goodman, 1969. Semen characteristics as influenced by selection for divergent growth rate in chickens. Poultry Sci. 48: 859865.
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on June 26, 2015
million per mm. 3 ). The low line had a highly significant (P s 0.01) lower methylene blue reduction time as compared to the high line (28.5 vs. 42.0 minutes). Differences in volume, motility and percent of live sperm between the two lines were not significant. Marini and Goodman (1969) reported that the low lines had highly significant differences for all of these traits. The two studies were conducted at different times (winter and summer) during the year and the different results may possibly indicate a strain-environmental interaction for certain semen traits in these lines similar to the month-breed interaction for semen volume reported by Saeid and Al-Soudi (1975). Differences in fertility and hatchability of fertile as well as total eggs were not significant. Hatchability percentages of fertile eggs were essentially the same (90.1 and 87.5%) for the high and low lines, respectively. Fertility tended to be higher, although not significant, in the low line (63.6 vs. 54.0%) than in the high line. The higher value for fertility was also reflected in the higher value for hatchability of total eggs in the low line. Although the same quantity of semen (0.05 cc.) was used, the higher concentration in the low line resulted in a slightly greater number of sperm being inseminated from the low line males. However, the concentration was sufficiently great in both lines to assure that the minimum 100,000,000 sperm per insemination recommended by Munro (1938)
Low 0.37 28.50 3,414,440.00 2.48 97.10 63.60 87.50 62.30
459
RESEARCH NOTES
McCartney, M. G., 1956. Relation between semen quality and fertilizing ability of White Holland turkeys. Poultry Sci. 35: 137-141. Munro, S. S., 1938. The effect of dilution and density on fertilizing capacity of fowl sperm suspensions. Can. J. Res. 16: 281-299. Saeid, J. M., and K. A. Al-Soudi, 1975. Seasonal variation in semen characteristics of White Leghorn, New Hampshire and indigenous chickens in Iraq.
Brit. Poultry Sci. 16: 97-102. Siegel, P. B., 1963. Selection for body weight at eight weeks of age. 2. Correlated response of feathering, body weights, and reproductive characteristics. Poultry Sci. 42: 896-905. Snedecor, G. W., and W. G. Cochran, 1967. Statistical Methods. The Iowa State University Press, Ames, Iowa.
J. E. THOMSON, N. A. Cox, J. S. BAILEY, J. H. HOLLADAY AND R. L. RICHARDSON U.S.D.A., A.R.S., Richard B. Russell Agricultural Research Center, P.O. Box 5677, Athens, Georgia 30604 (Received for publication August 28, 1975)
ABSTRACT Poultry carcasses were sampled for bacterial counts by two methods of swabbing an area of skin delineated by 12.3 cm.2 fiberboard template. In the first, or "standard" method, the skin could slip under the template during swabbing, thus an area larger than the nominal template area was swabbed. In the second method, skin slippage was prevented by an anchoring device, but the count did not differ significantly from the count by the first method. When swab sampling, random variations among counts were so great that the additional variation due to mean differences in size of area swabbed of ±2 cm.2 of nominal 12.3 cm.2 area did not significantly affect counts. POULTRY SCIENCE 55: 459-462, 1976
INTRODUCTION
AMPLING of poultry carcass skin surfaces for enumeration of bacteria on a specific area is usually performed by (1) swabbing with a cotton or alginate swab, (2) rinsing with a sampling fluid, or (3) excising and then blending the skin. Swabbing is most popular because it is rapid, simple, requires a minimum of materials, and is non-destructive of the product. The area to be swabbed is usually delineated by placing a piece of sterilized material such as fiberboard, kraft paper, or aluminum foil, in which a hole of specific dimension has been cut (template), on the meat or skin surface to be swabbed. In this laboratory, a fiberboard gasket with an inside area of 12.3 cm.2 has been used as a template (Kotula et al., 1962). Other researchers have swabbed
S
areas ranging from 1 cm.2 (Sanders and Blackshear, 1971) to 16 cm.2 (Patterson, 1972). The size of the area to be sampled might be a factor in swab sampling. Kinsley and Mountney (1966) found that a 2 cm.2 area gave a higher count per cm.2 than a 5 or 10 cm.2 area in 29 of 36 samples, although this difference was not statistically significant. A lower count per cm.2 on a large sampling area could result because a smaller proportion of the total bacteria present on the area are removed. Swabbing a large area may be advantageous, however, because it is more representative of the carcass as a whole. When a relatively large area (for example, 12.3 cm.2 internal diameter of the template) is swabbed, the skin on most carcasses would slip under the template slightly and form a
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on June 26, 2015
BACTERIOLOGICAL SAMPLING OF POULTRY CARCASSES BY A TEMPLATE-SWAB METHOD
M.
C H E N G 1 AND B . L.
GOODMAN
Animal Industries Department, Southern Illinois University, Carbondale, Illinois 62901 (Received for publication August 20, 1975)
ABSTRACT The effects of divergent growth selection for 18 generations on semen characteristics, fertility and hatchability were investigated. Males from the low weight line produced semen with a significantly (P < 0.05) higher sperm concentration and a highly significantly (P £ 0.01) lower methylene blue reduction time than the males from the high line. Differences between lines for semen volume, sperm motility, percent of live sperm, fertility and hatchability were not statistically significant. POULTRY SCIENCE 55: 457-459, 1976
IVERGENT selection for body weight in chickens have resulted in differences in size as well as other traits including semen characteristics (Siegel, 1963; Marini and Goodman, 1969; Edens et al, 1973). The purpose of this paper is to explore the influence of divergent growth selection on semen traits and the subsequent effect on fertility and hatchability. MATERIALS AND METHODS The lines (high and low) used in this study were the result of selection for growth rate in diverse directions for 18 generations (Maloney et al., 1967; and Marini and Goodman, 1969). Semen volume, sperm motility, concentration, methylene blue reduction time, and percent of live sperm were studied on three semen samples from each of 40 males from each line. The laboratory procedures for determining quality and quantity of semen were described by Marini and Goodman (1969). Semen from each male was used to inseminate five females. White Leghorn and randombred White Rock (Athens-Canadian) females were used to equally express the effects of egg size and egg weight (Landauer, 1961) and the possible adverse female effects
1. Present address: Department of Animal Science, University of Minnesota, St. Paul, Minnesota 55101.
457
on fertility in growth selected line (Edens et al., 1973). Hens were inseminated with 0.05 cc. semen on the first, second, eighth and ninth day of the trial. Eggs were pedigreed the second day after the first insemination and was continued for 14 days. An additional two-week period was used to allow the elapse of fertility prior to inseminating females with semen from other males. Females inseminated with semen from the high line during one trial were used to inseminate with semen from the low line males during the next trial to balance the possible variation due to dams on fertility and hatchability. Eggs were candled and the fertile ones transferred on the 19th day of incubation. The apparent infertiles were broken to determine early embryonic death macroscopically. Fertility, hatchability of fertile and total eggs, and live sperm were measured in percent and then adjusted by the arcsin transformation. All data were analyzed by analysis of variance technique as outlined by Snedecor and Cochran (1967). RESULTS AND DISCUSSION The average values for each line, difference between lines and level of significance for semen traits, fertility and hatchability data are given in Table 1. Concentration of sperm was significantly greater (P < 0.05) in the low line as compared to the concentration in the high line (approximation 3.4 vs. 2.9
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on June 26, 2015
D
458
REAEARCH NOTES
TABLE 1.—Average values and differences between lines for semen characteristics, fertility and hatchability Lines Traits Volume (cc.) MBRT (minutes) Concentration (mm. 3 ) Motility Live sperm (%) Fertility (%) Hatch fertile (%) Hatch total (%) * = P < 0.05. ** = P < 0.01.
High 0.39 42.00 2,882,910.00 2.17 97.00 54.00 90.10 55.80
Differences (High-Low) 0.02 13.50** -531,530.00* -0.31 -0.10 -9.60 2.60 -6.50
to ensure high fertility was met. In addition to the first insemination, birds were also inseminated on the second, eighth and ninth day. The low fertility was likely, in part, due to the age of the birds plus the high environmental temperature during the experiment. McCartney (1956) reported a highly significant correlation between duration of fertility and fertility. Duration of fertility data in the high and low lines were erratic; however, it would appear that fertility from the low line males increased more rapidly after insemination and was maintained at a slightly higher level than was the fertility from the high line males. Additional work is needed to determine if the significant diffferences in various semen traits are sufficiently great to significantly influence fertility and hatchability. REFERENCES Edens, F. W., H. P. Van Krey and P. B. Siegel, 1973. Selection for body weight at eight weeks of age. 10. Spermatozoal morphology. Poultry Sci. 52: 2287-2289. Landauer, W., 1961. The hatchability of chicken eggs as influenced by environment and heredity. Connecticut (Storrs) Agri. Expt. Sta. Mono. 1. Maloney, M. A., J. C. Gilbreath, J. F. Tierce and R. D. Morrison, 1967. Divergent selection for twelve-week body weight in the domestic fowl. Poultry Sci. 46: 1116-1127. Marini, P. J., and B. L. Goodman, 1969. Semen characteristics as influenced by selection for divergent growth rate in chickens. Poultry Sci. 48: 859865.
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on June 26, 2015
million per mm. 3 ). The low line had a highly significant (P s 0.01) lower methylene blue reduction time as compared to the high line (28.5 vs. 42.0 minutes). Differences in volume, motility and percent of live sperm between the two lines were not significant. Marini and Goodman (1969) reported that the low lines had highly significant differences for all of these traits. The two studies were conducted at different times (winter and summer) during the year and the different results may possibly indicate a strain-environmental interaction for certain semen traits in these lines similar to the month-breed interaction for semen volume reported by Saeid and Al-Soudi (1975). Differences in fertility and hatchability of fertile as well as total eggs were not significant. Hatchability percentages of fertile eggs were essentially the same (90.1 and 87.5%) for the high and low lines, respectively. Fertility tended to be higher, although not significant, in the low line (63.6 vs. 54.0%) than in the high line. The higher value for fertility was also reflected in the higher value for hatchability of total eggs in the low line. Although the same quantity of semen (0.05 cc.) was used, the higher concentration in the low line resulted in a slightly greater number of sperm being inseminated from the low line males. However, the concentration was sufficiently great in both lines to assure that the minimum 100,000,000 sperm per insemination recommended by Munro (1938)
Low 0.37 28.50 3,414,440.00 2.48 97.10 63.60 87.50 62.30
459
RESEARCH NOTES
McCartney, M. G., 1956. Relation between semen quality and fertilizing ability of White Holland turkeys. Poultry Sci. 35: 137-141. Munro, S. S., 1938. The effect of dilution and density on fertilizing capacity of fowl sperm suspensions. Can. J. Res. 16: 281-299. Saeid, J. M., and K. A. Al-Soudi, 1975. Seasonal variation in semen characteristics of White Leghorn, New Hampshire and indigenous chickens in Iraq.
Brit. Poultry Sci. 16: 97-102. Siegel, P. B., 1963. Selection for body weight at eight weeks of age. 2. Correlated response of feathering, body weights, and reproductive characteristics. Poultry Sci. 42: 896-905. Snedecor, G. W., and W. G. Cochran, 1967. Statistical Methods. The Iowa State University Press, Ames, Iowa.
J. E. THOMSON, N. A. Cox, J. S. BAILEY, J. H. HOLLADAY AND R. L. RICHARDSON U.S.D.A., A.R.S., Richard B. Russell Agricultural Research Center, P.O. Box 5677, Athens, Georgia 30604 (Received for publication August 28, 1975)
ABSTRACT Poultry carcasses were sampled for bacterial counts by two methods of swabbing an area of skin delineated by 12.3 cm.2 fiberboard template. In the first, or "standard" method, the skin could slip under the template during swabbing, thus an area larger than the nominal template area was swabbed. In the second method, skin slippage was prevented by an anchoring device, but the count did not differ significantly from the count by the first method. When swab sampling, random variations among counts were so great that the additional variation due to mean differences in size of area swabbed of ±2 cm.2 of nominal 12.3 cm.2 area did not significantly affect counts. POULTRY SCIENCE 55: 459-462, 1976
INTRODUCTION
AMPLING of poultry carcass skin surfaces for enumeration of bacteria on a specific area is usually performed by (1) swabbing with a cotton or alginate swab, (2) rinsing with a sampling fluid, or (3) excising and then blending the skin. Swabbing is most popular because it is rapid, simple, requires a minimum of materials, and is non-destructive of the product. The area to be swabbed is usually delineated by placing a piece of sterilized material such as fiberboard, kraft paper, or aluminum foil, in which a hole of specific dimension has been cut (template), on the meat or skin surface to be swabbed. In this laboratory, a fiberboard gasket with an inside area of 12.3 cm.2 has been used as a template (Kotula et al., 1962). Other researchers have swabbed
S
areas ranging from 1 cm.2 (Sanders and Blackshear, 1971) to 16 cm.2 (Patterson, 1972). The size of the area to be sampled might be a factor in swab sampling. Kinsley and Mountney (1966) found that a 2 cm.2 area gave a higher count per cm.2 than a 5 or 10 cm.2 area in 29 of 36 samples, although this difference was not statistically significant. A lower count per cm.2 on a large sampling area could result because a smaller proportion of the total bacteria present on the area are removed. Swabbing a large area may be advantageous, however, because it is more representative of the carcass as a whole. When a relatively large area (for example, 12.3 cm.2 internal diameter of the template) is swabbed, the skin on most carcasses would slip under the template slightly and form a
Downloaded from http://ps.oxfordjournals.org/ at Carleton University on June 26, 2015
BACTERIOLOGICAL SAMPLING OF POULTRY CARCASSES BY A TEMPLATE-SWAB METHOD