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Use of a Full Diallel Cross to Estimate General and Specific Combining Ability in Chickens1,2
1043
HEATING SOYBEAN MEAL
Kuiken, K. A., W. H. Norman, C. M. Lyman, F. Hale and L. Blotter, 1943. The microbiological determination of amino acids. I. Valine, leucine and isoleucine. J. Biol. Chem. 151: 615-626. Kwong, E., and R. H. Barnes, 1963. Effect of soybean trypsin inhibitor on methionine and cystine utilization. J. Nutrition, 8 1 : 392-398. Liener, I. E., 1962. Toxic factors in edible legumes and their elimination. Am. J. Chem. Nut. 11: 281-298. Mitchell, H. H., T. S. Hamilton and J. R. Beadles, 1945. The importance of commercial processing for the protein value of food products. I. Soybean, coconut and sunflower seed. J. Nutrition, 29: 13-25. Richardson, C. E., A. B. Watts, W. S. Wilkinson and J. M. Dixon, 1960. Techniques used in metabolism studies with surgically modified hens. Poultry Sci. 39: 432-440. Saxena, H. C , L. S. Jensen and J. McGinnis, 1962. Influence of dietary protein level on chick growth depression by raw soybean meal. J. Nutrition, 77: 241-244. Saxena, H. C , L. S. Jensen and J. McGinnis, 1963. Studies on mechanism of growth depression and pancreatic hypertrophy by raw soybean meal in the chick. Fed. Proc. 22: 200. Sturkie, P. D., 1954. Avian Physiology. Comstock Company, Ithaca, New York. Tinsley, J. and T. Z. Nowakowski, 1957. The determination of uric acid particularly in avian excreta. The Analyst, 82:110-116.
Use of a Full Diallel Cross to Estimate General and Specific Combining Ability in Chickens1'2 Departments
S. WEARDEN,3 D. TINDELL 4 AND J. V. CRAIG5 of Poultry Science and Statistics, Kansas State University,
Manhattan
(Received for publication December 28, 1964) INTRODUCTION
T
HE diallel cross has become a common method of analyzing intraspecific genetic variability among crosses 1
This investigation is part of the Kansas contribution to the NC-47 Regional Poultry Breeding Project. 2 Contribution No. 259, Department of Poultry Science and No. 57, Department of Statistics,
Kansas Agricultural Experiment Station, Manhattan, Kansas. 3 Department of Statistics, Kansas State University, Manhattan. * Coordinator, Southern Regional Poultry Breeding Project (S-57), A. R. S., U.S.D.A., Athens, Georgia. 6 Department of Poultry Science, Kansas State University, Manhattan.
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Carroll, R. W., G. W. Hensley and W. R. Graham, Jr., 1952. The site of nitrogen absorption in rats fed raw and heat treated soybean meals. Science, 115: 36-39. Conway, E. J., 1957. Microdiffusion Analysis and Volumetric Error, 4th ed., Crossby Lockwood and Son. London. Evans, R. J., and J. McGinnis, 1946. The influence of autoclaving soybean oil meal on the availability of cystine and methionine for the chick. J. Nutrition, 3 1 : 449-461. Evans, R. J., J. McGinnis and J. L. St. John, 1947. The influence of autoclaving soybean oil meal on the digestibility of the proteins. J. Nutrition, 3 3 : 661-672. Fisher, H., and D. Johnson, Jr., 1958. The effectiveness of essential amino acid supplementation in overcoming the growth depression of unheated soybean meal. Arch. Biochem. Biophys. 77: 124-128. Hawk, P. B., B. L. Oser and W. H. Summerson, 1947. Practical Physiological Chemistry, 13th ed., The Blakiston Co., Philadelphia. Hawley, E. E., J. R. Murlin, E. S. Nasset and T. A. Szymanski, 1948. Biological values of six partially purified proteins. J. Nutrition, 36: 153-169. Hayward, J. W., H. Steenbock and G. Bohstedt, 1936. The effect of heat as used in the extraction of soybean oil upon the nutritive value of the protein of soybean oil meal. J. Nutrition, 11: 219-234.
1044
S. WEAKDEN, D.
T I N D E L L AND J. V.
This study estimates the relative importance of general and specific combining ability and maternal influence in strain and breed crosses for certain economic traits in pullets. MATERIALS AND METHODS Experimental Stock. Samples of three White Leghorn (W.L.) and three Rhode Island Red (R.I.R.) "closed-flock" strains were obtained from leading commercial breeders in 1956 and crossed in all possible combinations to produce six "pure strains" and 30 strain and breed crosses in both 1957 and 1958. Two shifts of males were involved in reproducing the crosses each year. Each shift was composed of a different sample of males (nine males per strain and shift in 1957; six in 1958). Females producing pure strain progeny in the first shift were used to produce cross progeny in the second shift each year and vice versa. Management Procedures. All chicks in 1957 were sexed, wingbanded and vaccinated for Newcastle disease soon after hatching. T h e y were reared in b a t t e r y brooders until four weeks of age then moved to floor pens in two large brooder houses. At eight weeks of age all chicks were vaccinated for fowl pox and Newcastle disease by the wing-web method. In 1957, first shift pullets were confine-
ment reared and retained in the same house from eight weeks until the end of their laying year. Second shift females were moved to range houses a t eight weeks of age. At approximately five months of age all pullets on range and in confinement were housed, badged, debeaked and weighed to the nearest one tenth pound. In 1958 all chicks at hatching were dubbed and vaccinated for bronchitis and Newcastle disease. All pullets were moved to range a t eight weeks of age and housed at about five months of age. All other management procedures and measurements prior to housing were the same as described previously. All first shift pullets were housed in four pens of the same laying house both years, approximately 300 females per pen. Second shift females were housed in a different house in pens t h a t held approximately 100 birds each, except for one pen of about 300 birds. As nearly proportional numbers as possible were present for each of the 36 strain and breed combinations in each of the pens involved. Since the pure strain females of 1957-58 were used as breeders the following year, only part-year records to 260 days of age were available for analyses. However, in 1958-59, part- and full-year records were available for all combinations. Traits Studied. The traits studied in both years were: sexual maturity (age at first egg), hen-day percentage egg production to 260 days, hen-housed egg production to 260 days, and five- and ten-month body weight. In 1958, in addition, data were obtained for hen-day percentage and hen-housed egg production to 470 days of age (full-year record). Hen-day percentage egg production, as a measure of rate of lay, was calculated as total eggs laid on t r a p days from first egg to the end of the laying period divided by the total possible number of trap days in
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(partial diallel) or among parental subpopulations and their crosses (full diallel). The breeder needs the full diallel to determine whether crossing per se is of value in improving productivity. He needs further to determine the relative importance of certain kinds of specific combining ability, to indicate whether extensive crossing is needed to exploit nonadditive genetic variation. A diallel analysis that allows estimation of maternal effects is needed to determine whether reciprocal crosses are likely to be equivalent.
CKAIG
COMBINING ABILITY
the same period. All hens were trapnested three days per week. Hen-housed egg production was total eggs laid on trap days from the time of housing at 150 days of age until completion of the test period at 260 or 470 days of age. STATISTICAL METHODS
Yijkim = n+bi+b' j+sik-\-s' ji-\-{bb')n + (bs')in+
(b's)ijk+(ss')ijki
~\~ eijklm
Where: JJ, hi b'j
Sik
= the general mean, an effect common to all observations. = the effect due to the ith breed of sire. = the effect due to the jth breed of dam—the sum of a genetic and an uncorrelated maternal effect. = the effect due to the &th strain of sire within the ith breed of
sire. = the effect due to the /th strain of dam within the jth breed of dam—the sum of a genetic and an uncorrelated maternal effect. (bb'),, =the effect due to the interaction between the ith breed of sire and the^'th breed of dam. (bs')iji =the effect due to the interaction between the ith. breed of sire and the Ith strain of dam within the^'th breed of dam. {b's)ijk =the effect due to the interaction between the jth breed of dam and the &th strain of sire within the ith breed of sire. (ss')ijki= the effect due to the interaction of the £th strain within ith breed of sire with the Ith strain within thejth breed of dam. e%jk im a random effect peculiar to the ijklmth individual. The model assumes that, except for n, all components are uncorrelated variables with means zero and variances
Cs: b2, OS': b'2, &bb'2,
(rw2. In the linear model, a prime letter indicates that the effect is attributed to the dam. The colon used in the variance subscript notation indicates variability within the particular breed or cross noted to the right of the colon (Henderson, 1959, page 29). Variance component estimates were obtained within each shift of 1957 and 1958 for all traits. Estimates for each year were also calculated after pooling data for shifts within years. Variance component estimates were also obtained from data pooled over years. Only the estimates for each year and for years pooled are presented. However, persons interested in the estimates obtained within each shift of each year and for an example (sexual maturity) of how the
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Hatch Effects. Several hatches were involved in each shift of each year, therefore, all data were adjusted for hatch effects (Tindell, 1961), when necessary, before proceeding with variance component analyses. Linear Model and Analyses. Henderson (1953) described three methods of estimating variance components when unequal subclass numbers are involved. His first method was utilized in analyzing data from this experiment. Uncorrected sums of squares were computed in the usual fashion for unequal subclass numbers; equated to expectations obtained under the assumption of random effects (Model II of Eisenhart, 1947), and the resulting set of simultaneous equations solved to produce estimates of the different variance components. The linear model was assumed to be:
1045
1046
S. WEAEDEN, D.
T I N D E L L AND J. V.
Combining Ability in the Broad Sense. Sprague and T a t u m (1942) defined general and specific combining abilities within the context of a crossbreeding program. Thus, under the Sprague and T a t u m definitions, any covariances among relatives are computed about the mean of the F i generation (i.e. the mean of the crossbreds). Since the full diallel cross yields data on both purebreds and crossbreds, the covariances are computed about the general mean. Thus, if one uses a full diallel, he will not obtain the variances of general combining ability (g.c.a.) and specific combining ability (s.c.a.) as defined by Sprague and T a t u m (see Kempthorne, 1956, and Griffing, 1958). However, the intent of this study was to determine how individual genes and genetic interactions contribute to total genetic variability, rather than to variability among the Fi's. H a y m a n (1954) devised a set of four equations to partition the genetic variance obtained among matings in a full diallel cross. Following the notation of Yates (1947), he called one mean square a, which is genie variance, or the variance among the contributions of individual genes. Such variance is utilized through assortative mating. The three other mean
squares devised by H a y m a n explain the nature of particular types of genetic interaction. The first of these, bi, is obtained from the average difference between pure strains and their crosses. Heterosis is the genetic explanation of this form of variation. The second mean square, bi, is t h a t of the interaction between pure strains and the crosses derived from them. Strains t h a t do poorly in pure strain performance but consistently well in crosses, or vice versa, contribute to this variance. The final mean square for genetic interaction, h, is derived from the fortuitous combination of genes. There is probably little difference in the estimates of the variance of g.c.a. whether they arise from the analysis of a full diallel cross or a partial cross omitting pure strains (Griffing's Diallel Method II) unless 62 is significant. If b2 is significant, variance due to genetic interaction is attributed to the variance among single genes in the analysis of a partial diallel, and the estimates of the variance of g.c.a. from such an experiment are accordingly inflated. With respect to the variance of s.c.a., if the crosses have a sizable common deviation from their respective midparents, the nature of the diallel experiment affects not only the estimate of the size of this variance but possibly the decision of the most suitable breeding scheme. If crossing is uniformly beneficial, or harmful, only the analysis of a diallel including pure strains as well as crosses will determine this fact. It has already been noted t h a t 62 variation, a form of genetic interaction, is misinterpreted as variability among individual genes in partial diallel analysis and consequently inflates the estimate of g.c.a. variance. Only the variation due to fortuitous gene combinations, J3, remains to be interpreted as s.c.a. variance in such an experiment.
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estimates were computed are referred to Tindell (1961). This particular analysis has an advantage over t h a t proposed by Yates (1947) and later elaborated by H a y m a n (1954), Kempthorne (1956), and Griffing (1958); it permits the estimation of maternal effects. If maternal effects are present and the Yates model and analysis are used, the variance of maternal effects constitutes a positive bias in the mean square attributed to general combining ability (Wearden, 1964). The present linear model was adopted because maternal effects are not uncommon in vertebrates.
CRAIG
1047
COMBINING ABILITY
<7 6 2 1
= Gb
Includes sex-linked effects Is an underestimate to the extent that sexlinkage is present. 3 Includes genetic variability among families within strains and crosses. 2
a^
= Gb+Mb = GS
0-s:62 9
= GS+MS
"V: V
aw1 C6s: b'2
° V s : b2 2
=sb =s. =ss
° W : bb' =Sbs
°w
=E
Each estimate was then expressed as a proportion of the total variance, e.g., Gb
Gb+Mb+G.+M.+Sb+S.+St,+E Gb Total Variation = The percentage of variation due to breed general combining ability. All negative estimates were considered to be zero. RESULTS
Number of pullets housed per combination within each shift and year is shown in Table 1. The relative performances (unweighted means) of the mating systems involved are presented by years in Table 2. Since this paper did not propose to compare the performance of pure strains, strain crosses and breed crosses, persons interested in the relative performance of the mating systems may see Tindell, 1961. Estimates of relative variability due to breed and strain general combining ability, specific combining ability, maternal and random effects are given in Tables 3 and 4. In 1957 (Table 3) and 1958 (Table 4), breed specific combining ability was more important than all other parameters (excepting random variability) for sexual maturity and hen-housed egg production to 260 and 470 days. Strain specific combining ability was estimated to be the most important single
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The Sprague and Tatum terminology is in relatively common use among breeders. To retain familiar phraseology we shall define g.c.a. and s.c.a. in terms of combining ability in the broad sense when estimated from a full diallel cross. The definition equations of their variances are: o-ff2=Cov(P/C)
1048
S. WEAEDEN, D . TABLE 1 . --Number
T I N D E L L AND J. V. CRAIG
of put lets housed per combination within each shift and yeat 1957
Strains
1958
W.L. Breed
R.I.R. Breed
W.L. Breed
R.I.R. Breed
3
1
2
3
1
2
3
1
2
3
1
49* 35**
14 25
11 6
13 24
22 27
14 19
95 61
21 12
18 13
25 19
20 9
37 8
2
22 22
43 40
16 17
4 26
7 21
12 22
45 25
91 80
28 12
25 27
24 20
18 13
3
31 27
18 20
41 40
12 24
21 23
17 26
36 18
36 23
27 14
31 19
29 4
25 14
1
20 24
26 24
9 26
52 40
5 26
11 22
25 23
40 21
8 6
23 38
24 3
13 3
R.I.R. Breed 2
25 23
18 22
12 19
14 22
47 39
6 21
34 5
36 7
29 8
25 18
20 6
14 12
3
17 18
11 25
7 24
11 13
14 25
31 40
45 18
44 30
9 7
19 16
19 9
63 30
W.L. Breed
1957 Total = 1,600
Shift 1 Total =703 Shift 2 Total=897
1958 Total =1,772
Shift 1 = 1, 21 Shift 2 = 651
:
Shift 1 pullets are represented by the numbers in the upper row. '* Shift 2 pullets are represented by the numbers in the lower row.
parameter (excepting random variability) for part-year (to 260 days) hen-day percentage egg production in 1957 and also for the full-year record (to 470 days) in 1958. I t also contributed the second largest percentage of total variation (excepting random variability) in hen-housed egg production for both years. Breed and strain general combining abilities were estimated to be much less
important t h a n breed or strain specific combining ability for sexual maturity, part- and full-year hen-day and henhoused egg production. Breed general combining ability was estimated to be very important both years for five-month body weight and accounted for approximately 39 and 28 percent of total variation in 1957 and 1958, respectively. Estimates were even larger for
TABLE 2.—Performance levels {unweighted means) of traits by mating systems and years
Mating System
days Pure Strains W.L. R.I.R. Strain Crosses W.L. R.I.R. Breed Crosses W.L.XR.I.RR.I.R.XW.L. 1
Body Weight
Production to 260 Days of Age
Production to 470 Days of Age
Five Month Ten Month
Hen-day Hen-housed
Hen-day Hen-housed
Sexual Maturity
1
pounds
pounds
percent
No. eggs
percent
No. eggs
189 198
169 170
3.2 4.1
2.9 3.8
4.2 5.5
4.1 5.5
76 72
68 67
19 26 16 24
— —
59 55
— —
67 60
186 192
165 169
3.3 4.2
3.0 3.8
4.3 5.6
4.2 5.S
78 76
68 68
22 28 18 24
— —
62 58
— —
74 59
181 189
160 164
3.8 3.7
3.4 3.4
4.9 4.9
4.8 4.9
77 78
71 68
23 21
— —
62 62
— —
70 74
29 28
Values to the left are unweighted means for 1957; to the right for 1958.
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2
1
1049
COMBINING ABILITY
TABLE 3.—Estimates of parameters {1957) expressed as percentages of the total variation
Parameter
General C.A. Gb G, Specific C.A.
Sexual Maturity 1.91
Five Month
Ten Month
41.14
52.13
S, Sba
41.52
93.75
ten-month body weight, 49 and 52 percent of total variation. Estimates of strain general combining ability were lower than those of breed general combining ability. However, in three of four cases they still were larger than any estimates of specific combining ability for adult body weights. Breed maternal effects were estimated to be relatively important in determining five-month body weight, accounting for 16-17 percent of the total variability, and were more important for ten-month body weight in 1957 (Table 3) t h a n any estimate of s.c.a. Breed and strain maternal
1.49
0.82
0 1.49
0 0.82
3.13 0
16.18 0
0 0
8.41 3.49 0.52
0.41 2.05 0.82
3.13
16.18
0
12.42
3.28
86.09
95.49
44.13
effects were estimated less important relatively for part-year hen-day and henhoused egg production. Estimates for 1957 and 1958 were highly consistent (Tables 3 and 4), so data for the two years were pooled, mean squares equated to their expectations, and the equations solved for variance components as before. Estimates of parameters, obtained from variance components, are presented in Table 5 as percentages of total variation. Estimates obtained from pooling d a t a for the two years indicate specific combining ability (mainly breed s.c.a.) to be more important than any
TABLE 4.—Estimates of parameters {1958) expressed as percentages of the total variation Egg Production
Body Weight Parameter
Sexual Maturity
Ten Month
Five Month
to 260 days of age Hen-day
General C.A. 0 0 Gb G, 0 Specific C.A. 13.17 10.54 Sb 2.63 S, 0 Sis Maternal Effects 0.45 Mb 0 M, 0.45 Random Variability (E) 86.38
52.10 0
28.36 9.83
0 2.69 0.40
0 1.97 0 17.45
44.81
0
97.15
7.15 4.12 3.03 0 0.23
0
0.23 0
0 0
0 0 92.53
0 0
1.55 9.43 0
6.08 1.13 0.26
0 0
0 0
0
10.98
7.47
Hen-housed
0.22 0.44
0 0
0 0 1.42 1.07
0 17.45 0
Hen-day 0.66
0 0.36 0
1.42
3.09
1.97
42.39
0.36
52.10
38.19
Hen-housed
to 470 days of age
88.36
92.62
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Maternal Effects Mb Ms Random Variability (E)
0 0
0.41 0
0 0.29 0.32
0 0 1.16
3.63 0.33 0.38
0
0.41
0.61
1.16
4.34
Hen-housed
Hen-day
49.13 3.00
38.73 2.41
1.10 0.81
56
Egg production to 260 days of age
Body weight
1050
S. WEARDEN, D.
T I N D E L L AND J.
V.
CRAIG
TABLE 5.—Estimates of parameters expressed as percentages of the total variation when pooled over years
Parameter General C.A. G, G, Specific C.A. Sb Ss
Body Weight Five Month
Ten Month
Hen-day
0.26
39.66
51.95
0.38
Sis
42.13
other parameter (excepting random variability) for sexual maturity and part-year hen-housed egg production. Specific combining ability variance also accounted for the greatest proportion of total variations for part-year hen-day egg production (excepting random variability). General combining ability and maternal effects each accounted for a major proportion of the variability in five-month body weight, with breed g.c.a. and breed maternal effects much more important than strain g.c.a. or strain maternal effects. Strain g.c.a. was estimated to have some importance, but strain maternal effects were estimated to be zero. Over half of total variability in tenmonth body weight was attributed to breed general combining ability, with strain g.c.a. and maternal effects making u p less than one percent of total variability. DISCUSSION
Estimates of components of genetic variability have been made in several studies t h a t used other than a full diallel cross. Hazel and Lamoreaux (1947) used the hierarchical design, now known as North Carolina Model I because of its description by Comstock and Robinson (1948). W y a t t (1953) used a split plot design with male lines constituting whole
45.11
0.58 0.00 0.58
96.95
90.03
plots and tester female lines, subplots. Using North Carolina Model I I , with male lines crossed with female lines, Hill and Nordskog (1958) estimated general and specific combining abilities. Goto and Nordskog (1959) used a partial diallel cross omitting pure strains (Grimng's Diallel Method II) to make estimates. Yao (1961) made all possible crosses among lines and then examined the results according to the H a y m a n analysis and t h a t for Grimng's Method I I . In our study, estimates of general combining ability, and therefore additive genetic variation, were high for five- and ten-month body weights, which agrees with those of Hazel and Lamoreaux (1947) and those from both methods of analysis given by Yao (1961). Hill and Nordskog (1958) also reported a large variance in body weight due to g.c.a., b u t results are not directly comparable as they defined g.c.a. differently. Their a-/ was variance among male lines plus variance among female lines. Griffing (1958) has given a more nearly standard definition of aj2 as estimated from such a design. The importance of general combining ability with respect to sexual maturity was estimated to be small. Contrarily, Goto and Nordskog (1959) found large estimates of g.c.a. for t h a t trait for both white and brown-egg-type crosses of in-
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91.84
6.99 2.04 0.36
0.00 0.76
0.00 0.32
16.92 0.00
0.00 0.04
9.39
0.76
0.32
16.92
0.04
0.00 0.00
0.00 0.76 1.15
0.00 1.53 1.09
0.00 0.88 0.41
6.37 1.32 0.17
0
1.91
2.62
1.29
7.86
Hen-housed
0.38 0.00
51.95 0.00
33.19 6.47
0.00 0.26
Maternal Effects Mh Ms Random Variability (E)
Egg Production
Sexual Maturity
COMBINING ABILITY
and ten-week body weight had significant bi components in the first set of crosses. The variation due to fortuitous combination of genes, bz, was below significance for all traits in all sets of crosses. It is, therefore, not surprising that the study produced no significant estimates of s.c.a. variance when the data were reanalyzed according to Griffing's Diallel Method II. For, as was stated in statistical methods, genetic variation due to the b\ type of genetic interaction disappears from such an analysis, bi variation is incorporated in the estimate of a-g1, and only bz variation is left to be interpreted as
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bred lines. However, direct comparisons again must be avoided due to differences in design. Adding the 62 type of genetic interaction to the variation among individual genes in the estimate of
1051
1052
S. WEAEDEN, D.
T I N D E L L AND J. V.
Strain by breed interaction effects accounted for less than four percent of the explained variability for all traits except part-year hen-day percent production where they were estimated to account for 37.70% of the explained variability. Specific combining ability was estimated to be of major relative importance in this study for sexual maturity, partand full-year hen-day and hen-housed egg production. Maximum levels of performance for these traits would result from strain crossing. Procedures for locating the more productive crosses would vary depending on the relative importance of the
bi,
bz and
bz components of
more detailed examination of these components of genetic interaction will be presented separately. SUMMARY AND CONCLUSIONS
Three White Leghorn (W.L.) and three Rhode Island Red (R.I.R.) "closed-flock" strains were obtained from leading commercial breeders in 1956 and were crossed in all possible combinations to produce six "pure strains" and 30 strain and breed crosses in both 1957 and 1958. Measurements were taken on sexual
maturity, hen-day and hen-housed egg production to 260 and 470 days of age and five- and ten month body weight. Estimates of general and specific combining ability, maternal effects and random variation were pooled over shifts and years because of the consistency of the estimates. The estimates obtained indicated t h a t general combining ability was much more important than specific combining ability for five- and ten-month body weight. Contrarily, specific combining ability was estimated to be more important for sexual maturity, hen-day and hen-housed egg production to 260 and 470 days. Maternal effects were relatively important in determining five-month body weight. In accounting for the proportion of total variability t h a t could be explained, breed effects (Gb+St+Mt) were of major importance for all traits except hen-day percent production, where strain effects (Gs+Ss+Ms) were of greater importance. ACKNOWLEDGMENTS
We gratefully acknowledge the assistance of the breeders who supplied samples of these commercial stocks: Babcock, Ghostley and M o u n t Hope (White Leghorns) and Crooks, Harco Orchards and J. J. Warren (Rhode Island Reds). REFERENCES Comstock, R. E., and H. F. Robinson, 1948. The components of genetic variance in biparental progenies and their use in estimating the average degree of dominance. Biom. 4: 254-266. Eisenhart, C , 1947. The assumptions underlying the analysis of variance. Biom. 3: 1-21. Goto, E., and A. W. Nordskog, 1959. Heterosis in poultry. 4. Estimation of combining ability variance from diallel crosses of inbred lines in the fowl. Poultry Sci. 38: 1381-1388. Griffing, B., 1958. Application of sampling variables in the identification of methods which yield unbiased estimates of genotypic variance components. Australian J. Biol. Sci. 2: 219-245. Hayman, B. I., 1954. The analysis of variance of
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tion, they contribute 6.99% of the total variability and 70.11% of the explained variability. In the one year in which full-year egg production records were obtained, breed effects accounted for only 1.77% of total variability (15.21% of the explained variability) in hen-day production, but for full-year hen-housed production breed effects accounted for 4.35% of the total variation and 58.94% of the explained variability. Hen-day percent production (part- and full-year record) was the only trait for which strain effects (G„+S,+Af,) made u p a major proportion of the explained variability (49.84% and 84.79%, respectively).
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1053
COMBINING ABILITY
interaction with locations and years. Agron. J. 44: 462^66. Sprague, G. F., and L. A. Tatum, 1942. General vs. specific combining ability in single crosses of corn. J. Amer. Soc. Agron. 34: 923-932. Tindell, D., 1961. General and specific combining abilities, maternal effects and genotype-environmental interactions as estimated from strain and breed crosses of chickens. Ph.D. dissertation, Kansas State University, Manhattan. Wearden, S., 1964. Alternative analyses of the diallel cross. Heredity, 9: 669-680. Wyatt, A. J., 1953. Combining ability of inbred lines of Leghorns. Poultry Sci. 32: 400-405. Yao, T. S., 1961. Genetic variation in the progenies of the diallel crosses of inbred lines of chickens. Poultry Sci. 40: 1048-1059. Yates, F., 1947. The analysis of data from all possible reciprocal crosses between a set of parental lines. Heredity, 1: 287-302.
The Niacin Requirement of the Hen 1 R. C. RINGROSE, ATHANASIOS G. MANOUKAS, RAYMOND HINKSON AND A. E. TEERI Departments of Animal Sciences and Biochemistry, University of New Hampshire,
Durham
(Received for publication December 29, 1964)
N
IACIN is known to be required by several species of animals including poultry. However, the quantitative requirement of mature chickens is unknown. The Committee on Animal Nutrition of the National Research Council in its 1960 revision of the nutrient requirements of chickens, was unable to make a recommendation for a niacin requirement standard for laying and breeding hens because of lack of information. Dann and Handler (1941) and Snell and Quarles (1941) reported niacin synthesis by the developing chick embryo to the extent that the hatched chick contained 'Published with the approval of the Director of the New Hampshire Agricultural Experiment Station as Scientific Contribution No. 358.
ten to twenty times as much niacin as the unincubated egg. Briggs et at. (1942, 1943, 1945, 1946), in a series of papers reported that niacin is essential in the diet of the chick for optimal growth and to prevent "chick blacktongue"; described the symptoms of niacin deficiency in the chick, and concluded that tryptophan may replace niacin in purified diets for chicks. West et al. (1952) reported that excess tryptophan failed to compensate for a deficiency of niacin in chicks. However, the majority of evidence now indicates that tryptophan can be converted to niacin in several species, although there may be still some question of the conversion by poultry. There is agreement among research workers, however, that the reverse reaction does not occur.
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diallel crosses. Biom. 10: 235-244. Hazel, L. N., and W. F. Lamoreaux, 1947. Heritability, maternal effects and nicking in relation to sexual maturity and body weight in White Leghorns. Poultry Sci. 26: 508-514. Henderson, C. R., 1953. Estimation of variance and covariance components. Biom. 9: 226-252. Henderson, C. R., 1959. Techniques and Procedures in Animal Science. Design and analysis of animal husbandry experiments (pp. 1-55). American Society of Animal Production (Monograph). Hill, J. F., and A. W. Nordskog, 1958. Heterosis in poultry. 3. Predicting combining ability of performance in the crossbred fowl. Poultry Sci. 37: 1159-1169. Kempthorne, O., 1956. The theory of the diallel cross. Genetics, 41: 451-459. Rojas, B. A., and G. F. Sprague, 1952. A comparison of variance components in corn yield trials. III. General and specific combining ability and their
HEATING SOYBEAN MEAL
Kuiken, K. A., W. H. Norman, C. M. Lyman, F. Hale and L. Blotter, 1943. The microbiological determination of amino acids. I. Valine, leucine and isoleucine. J. Biol. Chem. 151: 615-626. Kwong, E., and R. H. Barnes, 1963. Effect of soybean trypsin inhibitor on methionine and cystine utilization. J. Nutrition, 8 1 : 392-398. Liener, I. E., 1962. Toxic factors in edible legumes and their elimination. Am. J. Chem. Nut. 11: 281-298. Mitchell, H. H., T. S. Hamilton and J. R. Beadles, 1945. The importance of commercial processing for the protein value of food products. I. Soybean, coconut and sunflower seed. J. Nutrition, 29: 13-25. Richardson, C. E., A. B. Watts, W. S. Wilkinson and J. M. Dixon, 1960. Techniques used in metabolism studies with surgically modified hens. Poultry Sci. 39: 432-440. Saxena, H. C , L. S. Jensen and J. McGinnis, 1962. Influence of dietary protein level on chick growth depression by raw soybean meal. J. Nutrition, 77: 241-244. Saxena, H. C , L. S. Jensen and J. McGinnis, 1963. Studies on mechanism of growth depression and pancreatic hypertrophy by raw soybean meal in the chick. Fed. Proc. 22: 200. Sturkie, P. D., 1954. Avian Physiology. Comstock Company, Ithaca, New York. Tinsley, J. and T. Z. Nowakowski, 1957. The determination of uric acid particularly in avian excreta. The Analyst, 82:110-116.
Use of a Full Diallel Cross to Estimate General and Specific Combining Ability in Chickens1'2 Departments
S. WEARDEN,3 D. TINDELL 4 AND J. V. CRAIG5 of Poultry Science and Statistics, Kansas State University,
Manhattan
(Received for publication December 28, 1964) INTRODUCTION
T
HE diallel cross has become a common method of analyzing intraspecific genetic variability among crosses 1
This investigation is part of the Kansas contribution to the NC-47 Regional Poultry Breeding Project. 2 Contribution No. 259, Department of Poultry Science and No. 57, Department of Statistics,
Kansas Agricultural Experiment Station, Manhattan, Kansas. 3 Department of Statistics, Kansas State University, Manhattan. * Coordinator, Southern Regional Poultry Breeding Project (S-57), A. R. S., U.S.D.A., Athens, Georgia. 6 Department of Poultry Science, Kansas State University, Manhattan.
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Carroll, R. W., G. W. Hensley and W. R. Graham, Jr., 1952. The site of nitrogen absorption in rats fed raw and heat treated soybean meals. Science, 115: 36-39. Conway, E. J., 1957. Microdiffusion Analysis and Volumetric Error, 4th ed., Crossby Lockwood and Son. London. Evans, R. J., and J. McGinnis, 1946. The influence of autoclaving soybean oil meal on the availability of cystine and methionine for the chick. J. Nutrition, 3 1 : 449-461. Evans, R. J., J. McGinnis and J. L. St. John, 1947. The influence of autoclaving soybean oil meal on the digestibility of the proteins. J. Nutrition, 3 3 : 661-672. Fisher, H., and D. Johnson, Jr., 1958. The effectiveness of essential amino acid supplementation in overcoming the growth depression of unheated soybean meal. Arch. Biochem. Biophys. 77: 124-128. Hawk, P. B., B. L. Oser and W. H. Summerson, 1947. Practical Physiological Chemistry, 13th ed., The Blakiston Co., Philadelphia. Hawley, E. E., J. R. Murlin, E. S. Nasset and T. A. Szymanski, 1948. Biological values of six partially purified proteins. J. Nutrition, 36: 153-169. Hayward, J. W., H. Steenbock and G. Bohstedt, 1936. The effect of heat as used in the extraction of soybean oil upon the nutritive value of the protein of soybean oil meal. J. Nutrition, 11: 219-234.
1044
S. WEAKDEN, D.
T I N D E L L AND J. V.
This study estimates the relative importance of general and specific combining ability and maternal influence in strain and breed crosses for certain economic traits in pullets. MATERIALS AND METHODS Experimental Stock. Samples of three White Leghorn (W.L.) and three Rhode Island Red (R.I.R.) "closed-flock" strains were obtained from leading commercial breeders in 1956 and crossed in all possible combinations to produce six "pure strains" and 30 strain and breed crosses in both 1957 and 1958. Two shifts of males were involved in reproducing the crosses each year. Each shift was composed of a different sample of males (nine males per strain and shift in 1957; six in 1958). Females producing pure strain progeny in the first shift were used to produce cross progeny in the second shift each year and vice versa. Management Procedures. All chicks in 1957 were sexed, wingbanded and vaccinated for Newcastle disease soon after hatching. T h e y were reared in b a t t e r y brooders until four weeks of age then moved to floor pens in two large brooder houses. At eight weeks of age all chicks were vaccinated for fowl pox and Newcastle disease by the wing-web method. In 1957, first shift pullets were confine-
ment reared and retained in the same house from eight weeks until the end of their laying year. Second shift females were moved to range houses a t eight weeks of age. At approximately five months of age all pullets on range and in confinement were housed, badged, debeaked and weighed to the nearest one tenth pound. In 1958 all chicks at hatching were dubbed and vaccinated for bronchitis and Newcastle disease. All pullets were moved to range a t eight weeks of age and housed at about five months of age. All other management procedures and measurements prior to housing were the same as described previously. All first shift pullets were housed in four pens of the same laying house both years, approximately 300 females per pen. Second shift females were housed in a different house in pens t h a t held approximately 100 birds each, except for one pen of about 300 birds. As nearly proportional numbers as possible were present for each of the 36 strain and breed combinations in each of the pens involved. Since the pure strain females of 1957-58 were used as breeders the following year, only part-year records to 260 days of age were available for analyses. However, in 1958-59, part- and full-year records were available for all combinations. Traits Studied. The traits studied in both years were: sexual maturity (age at first egg), hen-day percentage egg production to 260 days, hen-housed egg production to 260 days, and five- and ten-month body weight. In 1958, in addition, data were obtained for hen-day percentage and hen-housed egg production to 470 days of age (full-year record). Hen-day percentage egg production, as a measure of rate of lay, was calculated as total eggs laid on t r a p days from first egg to the end of the laying period divided by the total possible number of trap days in
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(partial diallel) or among parental subpopulations and their crosses (full diallel). The breeder needs the full diallel to determine whether crossing per se is of value in improving productivity. He needs further to determine the relative importance of certain kinds of specific combining ability, to indicate whether extensive crossing is needed to exploit nonadditive genetic variation. A diallel analysis that allows estimation of maternal effects is needed to determine whether reciprocal crosses are likely to be equivalent.
CKAIG
COMBINING ABILITY
the same period. All hens were trapnested three days per week. Hen-housed egg production was total eggs laid on trap days from the time of housing at 150 days of age until completion of the test period at 260 or 470 days of age. STATISTICAL METHODS
Yijkim = n+bi+b' j+sik-\-s' ji-\-{bb')n + (bs')in+
(b's)ijk+(ss')ijki
~\~ eijklm
Where: JJ, hi b'j
Sik
= the general mean, an effect common to all observations. = the effect due to the ith breed of sire. = the effect due to the jth breed of dam—the sum of a genetic and an uncorrelated maternal effect. = the effect due to the &th strain of sire within the ith breed of
sire. = the effect due to the /th strain of dam within the jth breed of dam—the sum of a genetic and an uncorrelated maternal effect. (bb'),, =the effect due to the interaction between the ith breed of sire and the^'th breed of dam. (bs')iji =the effect due to the interaction between the ith. breed of sire and the Ith strain of dam within the^'th breed of dam. {b's)ijk =the effect due to the interaction between the jth breed of dam and the &th strain of sire within the ith breed of sire. (ss')ijki= the effect due to the interaction of the £th strain within ith breed of sire with the Ith strain within thejth breed of dam. e%jk im a random effect peculiar to the ijklmth individual. The model assumes that, except for n, all components are uncorrelated variables with means zero and variances
Cs: b2, OS': b'2, &bb'2,
(rw2. In the linear model, a prime letter indicates that the effect is attributed to the dam. The colon used in the variance subscript notation indicates variability within the particular breed or cross noted to the right of the colon (Henderson, 1959, page 29). Variance component estimates were obtained within each shift of 1957 and 1958 for all traits. Estimates for each year were also calculated after pooling data for shifts within years. Variance component estimates were also obtained from data pooled over years. Only the estimates for each year and for years pooled are presented. However, persons interested in the estimates obtained within each shift of each year and for an example (sexual maturity) of how the
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Hatch Effects. Several hatches were involved in each shift of each year, therefore, all data were adjusted for hatch effects (Tindell, 1961), when necessary, before proceeding with variance component analyses. Linear Model and Analyses. Henderson (1953) described three methods of estimating variance components when unequal subclass numbers are involved. His first method was utilized in analyzing data from this experiment. Uncorrected sums of squares were computed in the usual fashion for unequal subclass numbers; equated to expectations obtained under the assumption of random effects (Model II of Eisenhart, 1947), and the resulting set of simultaneous equations solved to produce estimates of the different variance components. The linear model was assumed to be:
1045
1046
S. WEAEDEN, D.
T I N D E L L AND J. V.
Combining Ability in the Broad Sense. Sprague and T a t u m (1942) defined general and specific combining abilities within the context of a crossbreeding program. Thus, under the Sprague and T a t u m definitions, any covariances among relatives are computed about the mean of the F i generation (i.e. the mean of the crossbreds). Since the full diallel cross yields data on both purebreds and crossbreds, the covariances are computed about the general mean. Thus, if one uses a full diallel, he will not obtain the variances of general combining ability (g.c.a.) and specific combining ability (s.c.a.) as defined by Sprague and T a t u m (see Kempthorne, 1956, and Griffing, 1958). However, the intent of this study was to determine how individual genes and genetic interactions contribute to total genetic variability, rather than to variability among the Fi's. H a y m a n (1954) devised a set of four equations to partition the genetic variance obtained among matings in a full diallel cross. Following the notation of Yates (1947), he called one mean square a, which is genie variance, or the variance among the contributions of individual genes. Such variance is utilized through assortative mating. The three other mean
squares devised by H a y m a n explain the nature of particular types of genetic interaction. The first of these, bi, is obtained from the average difference between pure strains and their crosses. Heterosis is the genetic explanation of this form of variation. The second mean square, bi, is t h a t of the interaction between pure strains and the crosses derived from them. Strains t h a t do poorly in pure strain performance but consistently well in crosses, or vice versa, contribute to this variance. The final mean square for genetic interaction, h, is derived from the fortuitous combination of genes. There is probably little difference in the estimates of the variance of g.c.a. whether they arise from the analysis of a full diallel cross or a partial cross omitting pure strains (Griffing's Diallel Method II) unless 62 is significant. If b2 is significant, variance due to genetic interaction is attributed to the variance among single genes in the analysis of a partial diallel, and the estimates of the variance of g.c.a. from such an experiment are accordingly inflated. With respect to the variance of s.c.a., if the crosses have a sizable common deviation from their respective midparents, the nature of the diallel experiment affects not only the estimate of the size of this variance but possibly the decision of the most suitable breeding scheme. If crossing is uniformly beneficial, or harmful, only the analysis of a diallel including pure strains as well as crosses will determine this fact. It has already been noted t h a t 62 variation, a form of genetic interaction, is misinterpreted as variability among individual genes in partial diallel analysis and consequently inflates the estimate of g.c.a. variance. Only the variation due to fortuitous gene combinations, J3, remains to be interpreted as s.c.a. variance in such an experiment.
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estimates were computed are referred to Tindell (1961). This particular analysis has an advantage over t h a t proposed by Yates (1947) and later elaborated by H a y m a n (1954), Kempthorne (1956), and Griffing (1958); it permits the estimation of maternal effects. If maternal effects are present and the Yates model and analysis are used, the variance of maternal effects constitutes a positive bias in the mean square attributed to general combining ability (Wearden, 1964). The present linear model was adopted because maternal effects are not uncommon in vertebrates.
CRAIG
1047
COMBINING ABILITY
<7 6 2 1
= Gb
Includes sex-linked effects Is an underestimate to the extent that sexlinkage is present. 3 Includes genetic variability among families within strains and crosses. 2
a^
= Gb+Mb = GS
0-s:62 9
= GS+MS
"V: V
aw1 C6s: b'2
° V s : b2 2
=sb =s. =ss
° W : bb' =Sbs
°w
=E
Each estimate was then expressed as a proportion of the total variance, e.g., Gb
Gb+Mb+G.+M.+Sb+S.+St,+E Gb Total Variation = The percentage of variation due to breed general combining ability. All negative estimates were considered to be zero. RESULTS
Number of pullets housed per combination within each shift and year is shown in Table 1. The relative performances (unweighted means) of the mating systems involved are presented by years in Table 2. Since this paper did not propose to compare the performance of pure strains, strain crosses and breed crosses, persons interested in the relative performance of the mating systems may see Tindell, 1961. Estimates of relative variability due to breed and strain general combining ability, specific combining ability, maternal and random effects are given in Tables 3 and 4. In 1957 (Table 3) and 1958 (Table 4), breed specific combining ability was more important than all other parameters (excepting random variability) for sexual maturity and hen-housed egg production to 260 and 470 days. Strain specific combining ability was estimated to be the most important single
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The Sprague and Tatum terminology is in relatively common use among breeders. To retain familiar phraseology we shall define g.c.a. and s.c.a. in terms of combining ability in the broad sense when estimated from a full diallel cross. The definition equations of their variances are: o-ff2=Cov(P/C)
1048
S. WEAEDEN, D . TABLE 1 . --Number
T I N D E L L AND J. V. CRAIG
of put lets housed per combination within each shift and yeat 1957
Strains
1958
W.L. Breed
R.I.R. Breed
W.L. Breed
R.I.R. Breed
3
1
2
3
1
2
3
1
2
3
1
49* 35**
14 25
11 6
13 24
22 27
14 19
95 61
21 12
18 13
25 19
20 9
37 8
2
22 22
43 40
16 17
4 26
7 21
12 22
45 25
91 80
28 12
25 27
24 20
18 13
3
31 27
18 20
41 40
12 24
21 23
17 26
36 18
36 23
27 14
31 19
29 4
25 14
1
20 24
26 24
9 26
52 40
5 26
11 22
25 23
40 21
8 6
23 38
24 3
13 3
R.I.R. Breed 2
25 23
18 22
12 19
14 22
47 39
6 21
34 5
36 7
29 8
25 18
20 6
14 12
3
17 18
11 25
7 24
11 13
14 25
31 40
45 18
44 30
9 7
19 16
19 9
63 30
W.L. Breed
1957 Total = 1,600
Shift 1 Total =703 Shift 2 Total=897
1958 Total =1,772
Shift 1 = 1, 21 Shift 2 = 651
:
Shift 1 pullets are represented by the numbers in the upper row. '* Shift 2 pullets are represented by the numbers in the lower row.
parameter (excepting random variability) for part-year (to 260 days) hen-day percentage egg production in 1957 and also for the full-year record (to 470 days) in 1958. I t also contributed the second largest percentage of total variation (excepting random variability) in hen-housed egg production for both years. Breed and strain general combining abilities were estimated to be much less
important t h a n breed or strain specific combining ability for sexual maturity, part- and full-year hen-day and henhoused egg production. Breed general combining ability was estimated to be very important both years for five-month body weight and accounted for approximately 39 and 28 percent of total variation in 1957 and 1958, respectively. Estimates were even larger for
TABLE 2.—Performance levels {unweighted means) of traits by mating systems and years
Mating System
days Pure Strains W.L. R.I.R. Strain Crosses W.L. R.I.R. Breed Crosses W.L.XR.I.RR.I.R.XW.L. 1
Body Weight
Production to 260 Days of Age
Production to 470 Days of Age
Five Month Ten Month
Hen-day Hen-housed
Hen-day Hen-housed
Sexual Maturity
1
pounds
pounds
percent
No. eggs
percent
No. eggs
189 198
169 170
3.2 4.1
2.9 3.8
4.2 5.5
4.1 5.5
76 72
68 67
19 26 16 24
— —
59 55
— —
67 60
186 192
165 169
3.3 4.2
3.0 3.8
4.3 5.6
4.2 5.S
78 76
68 68
22 28 18 24
— —
62 58
— —
74 59
181 189
160 164
3.8 3.7
3.4 3.4
4.9 4.9
4.8 4.9
77 78
71 68
23 21
— —
62 62
— —
70 74
29 28
Values to the left are unweighted means for 1957; to the right for 1958.
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2
1
1049
COMBINING ABILITY
TABLE 3.—Estimates of parameters {1957) expressed as percentages of the total variation
Parameter
General C.A. Gb G, Specific C.A.
Sexual Maturity 1.91
Five Month
Ten Month
41.14
52.13
S, Sba
41.52
93.75
ten-month body weight, 49 and 52 percent of total variation. Estimates of strain general combining ability were lower than those of breed general combining ability. However, in three of four cases they still were larger than any estimates of specific combining ability for adult body weights. Breed maternal effects were estimated to be relatively important in determining five-month body weight, accounting for 16-17 percent of the total variability, and were more important for ten-month body weight in 1957 (Table 3) t h a n any estimate of s.c.a. Breed and strain maternal
1.49
0.82
0 1.49
0 0.82
3.13 0
16.18 0
0 0
8.41 3.49 0.52
0.41 2.05 0.82
3.13
16.18
0
12.42
3.28
86.09
95.49
44.13
effects were estimated less important relatively for part-year hen-day and henhoused egg production. Estimates for 1957 and 1958 were highly consistent (Tables 3 and 4), so data for the two years were pooled, mean squares equated to their expectations, and the equations solved for variance components as before. Estimates of parameters, obtained from variance components, are presented in Table 5 as percentages of total variation. Estimates obtained from pooling d a t a for the two years indicate specific combining ability (mainly breed s.c.a.) to be more important than any
TABLE 4.—Estimates of parameters {1958) expressed as percentages of the total variation Egg Production
Body Weight Parameter
Sexual Maturity
Ten Month
Five Month
to 260 days of age Hen-day
General C.A. 0 0 Gb G, 0 Specific C.A. 13.17 10.54 Sb 2.63 S, 0 Sis Maternal Effects 0.45 Mb 0 M, 0.45 Random Variability (E) 86.38
52.10 0
28.36 9.83
0 2.69 0.40
0 1.97 0 17.45
44.81
0
97.15
7.15 4.12 3.03 0 0.23
0
0.23 0
0 0
0 0 92.53
0 0
1.55 9.43 0
6.08 1.13 0.26
0 0
0 0
0
10.98
7.47
Hen-housed
0.22 0.44
0 0
0 0 1.42 1.07
0 17.45 0
Hen-day 0.66
0 0.36 0
1.42
3.09
1.97
42.39
0.36
52.10
38.19
Hen-housed
to 470 days of age
88.36
92.62
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Maternal Effects Mb Ms Random Variability (E)
0 0
0.41 0
0 0.29 0.32
0 0 1.16
3.63 0.33 0.38
0
0.41
0.61
1.16
4.34
Hen-housed
Hen-day
49.13 3.00
38.73 2.41
1.10 0.81
56
Egg production to 260 days of age
Body weight
1050
S. WEARDEN, D.
T I N D E L L AND J.
V.
CRAIG
TABLE 5.—Estimates of parameters expressed as percentages of the total variation when pooled over years
Parameter General C.A. G, G, Specific C.A. Sb Ss
Body Weight Five Month
Ten Month
Hen-day
0.26
39.66
51.95
0.38
Sis
42.13
other parameter (excepting random variability) for sexual maturity and part-year hen-housed egg production. Specific combining ability variance also accounted for the greatest proportion of total variations for part-year hen-day egg production (excepting random variability). General combining ability and maternal effects each accounted for a major proportion of the variability in five-month body weight, with breed g.c.a. and breed maternal effects much more important than strain g.c.a. or strain maternal effects. Strain g.c.a. was estimated to have some importance, but strain maternal effects were estimated to be zero. Over half of total variability in tenmonth body weight was attributed to breed general combining ability, with strain g.c.a. and maternal effects making u p less than one percent of total variability. DISCUSSION
Estimates of components of genetic variability have been made in several studies t h a t used other than a full diallel cross. Hazel and Lamoreaux (1947) used the hierarchical design, now known as North Carolina Model I because of its description by Comstock and Robinson (1948). W y a t t (1953) used a split plot design with male lines constituting whole
45.11
0.58 0.00 0.58
96.95
90.03
plots and tester female lines, subplots. Using North Carolina Model I I , with male lines crossed with female lines, Hill and Nordskog (1958) estimated general and specific combining abilities. Goto and Nordskog (1959) used a partial diallel cross omitting pure strains (Grimng's Diallel Method II) to make estimates. Yao (1961) made all possible crosses among lines and then examined the results according to the H a y m a n analysis and t h a t for Grimng's Method I I . In our study, estimates of general combining ability, and therefore additive genetic variation, were high for five- and ten-month body weights, which agrees with those of Hazel and Lamoreaux (1947) and those from both methods of analysis given by Yao (1961). Hill and Nordskog (1958) also reported a large variance in body weight due to g.c.a., b u t results are not directly comparable as they defined g.c.a. differently. Their a-/ was variance among male lines plus variance among female lines. Griffing (1958) has given a more nearly standard definition of aj2 as estimated from such a design. The importance of general combining ability with respect to sexual maturity was estimated to be small. Contrarily, Goto and Nordskog (1959) found large estimates of g.c.a. for t h a t trait for both white and brown-egg-type crosses of in-
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91.84
6.99 2.04 0.36
0.00 0.76
0.00 0.32
16.92 0.00
0.00 0.04
9.39
0.76
0.32
16.92
0.04
0.00 0.00
0.00 0.76 1.15
0.00 1.53 1.09
0.00 0.88 0.41
6.37 1.32 0.17
0
1.91
2.62
1.29
7.86
Hen-housed
0.38 0.00
51.95 0.00
33.19 6.47
0.00 0.26
Maternal Effects Mh Ms Random Variability (E)
Egg Production
Sexual Maturity
COMBINING ABILITY
and ten-week body weight had significant bi components in the first set of crosses. The variation due to fortuitous combination of genes, bz, was below significance for all traits in all sets of crosses. It is, therefore, not surprising that the study produced no significant estimates of s.c.a. variance when the data were reanalyzed according to Griffing's Diallel Method II. For, as was stated in statistical methods, genetic variation due to the b\ type of genetic interaction disappears from such an analysis, bi variation is incorporated in the estimate of a-g1, and only bz variation is left to be interpreted as
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bred lines. However, direct comparisons again must be avoided due to differences in design. Adding the 62 type of genetic interaction to the variation among individual genes in the estimate of
1051
1052
S. WEAEDEN, D.
T I N D E L L AND J. V.
Strain by breed interaction effects accounted for less than four percent of the explained variability for all traits except part-year hen-day percent production where they were estimated to account for 37.70% of the explained variability. Specific combining ability was estimated to be of major relative importance in this study for sexual maturity, partand full-year hen-day and hen-housed egg production. Maximum levels of performance for these traits would result from strain crossing. Procedures for locating the more productive crosses would vary depending on the relative importance of the
bi,
bz and
bz components of
more detailed examination of these components of genetic interaction will be presented separately. SUMMARY AND CONCLUSIONS
Three White Leghorn (W.L.) and three Rhode Island Red (R.I.R.) "closed-flock" strains were obtained from leading commercial breeders in 1956 and were crossed in all possible combinations to produce six "pure strains" and 30 strain and breed crosses in both 1957 and 1958. Measurements were taken on sexual
maturity, hen-day and hen-housed egg production to 260 and 470 days of age and five- and ten month body weight. Estimates of general and specific combining ability, maternal effects and random variation were pooled over shifts and years because of the consistency of the estimates. The estimates obtained indicated t h a t general combining ability was much more important than specific combining ability for five- and ten-month body weight. Contrarily, specific combining ability was estimated to be more important for sexual maturity, hen-day and hen-housed egg production to 260 and 470 days. Maternal effects were relatively important in determining five-month body weight. In accounting for the proportion of total variability t h a t could be explained, breed effects (Gb+St+Mt) were of major importance for all traits except hen-day percent production, where strain effects (Gs+Ss+Ms) were of greater importance. ACKNOWLEDGMENTS
We gratefully acknowledge the assistance of the breeders who supplied samples of these commercial stocks: Babcock, Ghostley and M o u n t Hope (White Leghorns) and Crooks, Harco Orchards and J. J. Warren (Rhode Island Reds). REFERENCES Comstock, R. E., and H. F. Robinson, 1948. The components of genetic variance in biparental progenies and their use in estimating the average degree of dominance. Biom. 4: 254-266. Eisenhart, C , 1947. The assumptions underlying the analysis of variance. Biom. 3: 1-21. Goto, E., and A. W. Nordskog, 1959. Heterosis in poultry. 4. Estimation of combining ability variance from diallel crosses of inbred lines in the fowl. Poultry Sci. 38: 1381-1388. Griffing, B., 1958. Application of sampling variables in the identification of methods which yield unbiased estimates of genotypic variance components. Australian J. Biol. Sci. 2: 219-245. Hayman, B. I., 1954. The analysis of variance of
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tion, they contribute 6.99% of the total variability and 70.11% of the explained variability. In the one year in which full-year egg production records were obtained, breed effects accounted for only 1.77% of total variability (15.21% of the explained variability) in hen-day production, but for full-year hen-housed production breed effects accounted for 4.35% of the total variation and 58.94% of the explained variability. Hen-day percent production (part- and full-year record) was the only trait for which strain effects (G„+S,+Af,) made u p a major proportion of the explained variability (49.84% and 84.79%, respectively).
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interaction with locations and years. Agron. J. 44: 462^66. Sprague, G. F., and L. A. Tatum, 1942. General vs. specific combining ability in single crosses of corn. J. Amer. Soc. Agron. 34: 923-932. Tindell, D., 1961. General and specific combining abilities, maternal effects and genotype-environmental interactions as estimated from strain and breed crosses of chickens. Ph.D. dissertation, Kansas State University, Manhattan. Wearden, S., 1964. Alternative analyses of the diallel cross. Heredity, 9: 669-680. Wyatt, A. J., 1953. Combining ability of inbred lines of Leghorns. Poultry Sci. 32: 400-405. Yao, T. S., 1961. Genetic variation in the progenies of the diallel crosses of inbred lines of chickens. Poultry Sci. 40: 1048-1059. Yates, F., 1947. The analysis of data from all possible reciprocal crosses between a set of parental lines. Heredity, 1: 287-302.
The Niacin Requirement of the Hen 1 R. C. RINGROSE, ATHANASIOS G. MANOUKAS, RAYMOND HINKSON AND A. E. TEERI Departments of Animal Sciences and Biochemistry, University of New Hampshire,
Durham
(Received for publication December 29, 1964)
N
IACIN is known to be required by several species of animals including poultry. However, the quantitative requirement of mature chickens is unknown. The Committee on Animal Nutrition of the National Research Council in its 1960 revision of the nutrient requirements of chickens, was unable to make a recommendation for a niacin requirement standard for laying and breeding hens because of lack of information. Dann and Handler (1941) and Snell and Quarles (1941) reported niacin synthesis by the developing chick embryo to the extent that the hatched chick contained 'Published with the approval of the Director of the New Hampshire Agricultural Experiment Station as Scientific Contribution No. 358.
ten to twenty times as much niacin as the unincubated egg. Briggs et at. (1942, 1943, 1945, 1946), in a series of papers reported that niacin is essential in the diet of the chick for optimal growth and to prevent "chick blacktongue"; described the symptoms of niacin deficiency in the chick, and concluded that tryptophan may replace niacin in purified diets for chicks. West et al. (1952) reported that excess tryptophan failed to compensate for a deficiency of niacin in chicks. However, the majority of evidence now indicates that tryptophan can be converted to niacin in several species, although there may be still some question of the conversion by poultry. There is agreement among research workers, however, that the reverse reaction does not occur.
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diallel crosses. Biom. 10: 235-244. Hazel, L. N., and W. F. Lamoreaux, 1947. Heritability, maternal effects and nicking in relation to sexual maturity and body weight in White Leghorns. Poultry Sci. 26: 508-514. Henderson, C. R., 1953. Estimation of variance and covariance components. Biom. 9: 226-252. Henderson, C. R., 1959. Techniques and Procedures in Animal Science. Design and analysis of animal husbandry experiments (pp. 1-55). American Society of Animal Production (Monograph). Hill, J. F., and A. W. Nordskog, 1958. Heterosis in poultry. 3. Predicting combining ability of performance in the crossbred fowl. Poultry Sci. 37: 1159-1169. Kempthorne, O., 1956. The theory of the diallel cross. Genetics, 41: 451-459. Rojas, B. A., and G. F. Sprague, 1952. A comparison of variance components in corn yield trials. III. General and specific combining ability and their