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Evaluation of Five Commercial Broiler Crosses
MARKETING AND PRODUCTS Evaluation of Five Commercial Broiler Crosses. 2. Eviscerated Yield and Component Parts. J.W.MERKLEY Us Department of Agriculture, Science and Education Administration, Poultry Research Laboratory, RD 2, Box 600, Georgetown, Delaware 19947 B. T. WEINLAND Administration,
G. W. MALONE and G. W. CHALOUPKA University of Delaware, Georgetown, Delaware 19947 (Received for publication August 1, 1979) ABSTRACT The eviscerated yields and carcass characteristics of five commercial broiler crosses were evaluated. In each of four trials, processed in December, March, June, and September, 33 birds from each cross and each sex were used. Individual live weights were recorded at 56 days of age, prior to feed withdrawal, and immediately before processing (plant weight). The fresh eviscerated carcass weight, neck, abdominal fat, liver, gizzard, and heart weights were evaluated as a percentage of the plant weight. The relative yields of parts, breast, back, wings, legs, and thighs were determined for both sexes of each cross. No significant differences were observed in the loss of weight from the 56 day to the plant weight between crosses in any trial. In all trials, differences in plant weights between crosses were statistically significant (P<.01) when weights for both sexes were combined. When data from the four trials were combined, the cross X trial interaction for plant weights was significant (P<.01). The fresh eviscerated carcass yields were not significantly influenced by the cross or sex of broilers in any trial. The amount of abdominal fat was the largest single significant (P<.01) source of variation among the commercial yield of broiler crosses. When cut into parts, carcasses from female broilers had a significantly (P<.01) greater proportion of breast and back than male carcasses. (Key words: viscerated yields, abdominal fat, parts yield, broiler crosses) 1980 Poultry Science 59:1755-1760 INTRODUCTION It is h u m a n nature t o m a k e comparisons. When we find m o r e t h a n one of anything, our curiosity compels us t o ask which is the fastest, the most economical, or the best suited for a particular need. In t h e poultry industry, with n u m e r o u s broiler crosses commercially available, it is of major economic i m p o r t a n c e to d e t e r m i n e the performance of these broilers. T h e yield of edible p r o d u c t after processing is the final factor u p o n which an integrated c o m p a n y can calculate its efficiency and cost of p r o d u c t i o n . Factors affecting t h e yield of p r o d u c t obviously c o n t r i b u t e significantly to the profit or loss a c o m p a n y realizes. Because a large volume of processed broilers are m a r k e t e d in a further processed or cut-up form, yield of the various parts is also very i m p o r t a n t in evaluating t h e performance of a particular cross of broiler. Mo ran et al. ( 1 9 7 0 ) assessed die variation enc o u n t e r e d in t h e p r o d u c t i o n and processing of
White Rock and Cornish breeds with their reciprocal crosses. These authors r e p o r t e d better growth and feed conversion by the t w o crosses than by either breed alone. The Cornish male x White R o c k female had t h e best growth and feed conversion. Moran et al. ( 1 9 7 0 ) reported n o substantial influence of breed on t h e dressing performance or yield of commercial cuts from any of t h e chilled carcasses. Hayse and Marion ( 1 9 7 3 ) d e t e r m i n e d t h e eviscerated yield a n d c o m p o n e n t parts for b o t h sexes of a single breed at 8 weeks of age. They concluded that the relative yield and percentage of the various parts had n o t changed appreciably from t h a t r e p o r t e d in t h e ptevious 2 0 years. What had changed was a reduction in t h e m a r k e t age from 10 t o 8 weeks. B o u w k a m p et al. ( 1 9 7 3 ) studied t h e strain influence on t h e yield of broiler parts witli H u b b a r d X A r b o r Acre and Vantress X A r b o r Acre crosses. They r e p o r t e d a larger yield of
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US Department of Agriculture, Science and Education Beltsville, Maryland 20705
1756
M E R K L E Y ET AL.
PROCEDURES
Five commercially available broiler crosses were selected for the study. These crosses were: Hubbard (d) X Hubbard (9) (H X H) ; Hubbard (d) X HN (?) (H X HN); Hubbard (d) x Shaver (9) (H x S) ; Ross (d) X Hubbard (9) (R x H) ; and Ross (d) X Arbor Acre (9) (R X AA). In each of the four trials conducted, an effort was made to obtain eggs from at least two breeder flocks of the same age per cross. The eggs were hatched and the birds reared according to standard practices as described by Malone et al. (1979). Triplicate pens of 175 birds (743 cm 2 /bird) were used for each sex of the five crosses. When the birds reached 56 days of age, a representative sample was randomly selected from each of the 30 pens. Birds exhibiting obvious deformities or grossly abnormal weight were rejected. A final sample of 11 broilers from each pen were wing banded, weighed, and placed in a holding pen with feed and water available ad libitum. The feed and water were withdrawn approximately 10 hr before slaughter. The following day (57 days of age) the birds were placed in coops according to the pens from which they were originally removed and processed by the coop in a predetermined order to minimize the effect of holding time upon the yield data. Birds were processed in December, 1975, and March, June, and September, 1976, for trials 1, 2, 3, and 4, respectively.
As birds were removed from the coops for processing, individual weights (plant weights) were obtained. The 3 30 birds used in each trial were processed within a 4-hr period, and withdrawal time ranged from 10 to 14 hr. Birds were hung on shackles, immobilized with electrical stunning, and killed by the modified Kosher method. After a 90-second bleed time, they were scalded at 60 C for 90 sec in a rotating batch scalder. A centrifugical batch-type picker (90 sec) was used for feather removal. The heads and shanks were removed, and the modified New York Dressed carcasses were iced down overnight to facilitate the removal and weighing of the abdominal fat pad. The following morning the birds were eviscerated, and the fresh eviscerated carcass, abdominal fat pad, liver, gizzard, heart, and neck weights were recorded. The carcass weight was obtained with the lungs removed and the kidneys intact. The preen gland was not removed and is included in the back weights. The weight of the abdominal fat pad included all fat from around the gizzard and the abdominal cavity. Gizzards were weighed after peeling. Hearts were weighed without further trimming of attached vessels or removal of clotted blood. Eviscerated carcasses were iced down until the following day when che five major parts (breast, back, wings, legs, and thighs) were weighed. In each trial, one person made all of a particular type of cut with a knife. The wings were separated from the carcass at the shoulder leaving as much meat as possible on the breast. The backs contained both the gluteus muscle (oyster) and the pelvic meat. The breast was separated from the back at the shoulder and along the junction of the vertebral and sternal ribs. The percentages of the individual parts are based upon the combined weight of the parts obtained after cutting. Analysis of variance (Snedecor and Cochran, 1968) and Duncan's multiple range test (1955) were used to determine the significance of mean differences. RESULTS A N D DISCUSSION
Plant weights of the male and female birds in each trial are presented in Table 1. Differences were significant (P<.05) in the live weights among crosses in all four trials with the exception of the females in trials three and four. The cross X trial interaction for plant weights was significant (P<.05). For instance, in trials 1 and 2, the weights of the H X S males were
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breast and back and a smaller yield of wings and legs from the Hubbard offspring. Singh and Essary (1974) determined the influence of age and sex on the dressing percentage of broilers. Dressing percentages were similar between sexes for broilers of the same age. However, values were significantly (P<.05) different among broilers of different ages when values for sexes were combined. Further reference to this subject can be found in the detailed bulletin by Carlson et al. (1975). The purpose of this study was to obtain information on the fresh eviscerated carcass yields, the percentage of parts from five commercial crosses, and the variations in yields among four seasonal flocks. This information might be useful in evaluating efficiency and maximizing profits under commercial conditions. The study was conducted in conjunction with another reported by Malone et al. (1979) concerned with evaluating the grow-out performance of the same five commercial broiler crosses.
BROILER EVISCERATED AND COMPONENT PARTS YIELDS
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TABLE 1. Plant weight of male and female broilers at 56 days (g) Cross
Observations 1
H X HN
H X S
RX H
R X AA
SE 2
P3
33 33
2158a.k 1757ab,kl
2050b,l 1655C1
2187a.k 1785a.k
2047b,l 1698bc,kl
2136a.kl 1716abc,kl
25.4 25.4
<.01 <.01
Male Female
33 33
2368a.k 1886a.k
2287b,kl 1783be,kl
2180C1 180iabc,kl
2256 b <:,l 1853ab-kl
2293ab.kl 1766C1
25.7 25.7
<.01 <.01
3 June
Male Female
33 33
2320a 1832
2226b 1786
2242ab 1763
2215b 1824
2280ab 1764
26.6 26.6
<.05 NS
4 Sept
Male Female
33 33
2134ab,kl
2l2lbc,kl
2l42ab,kl
1705
1690
1691
2209 a >k 1718
2052C1 1679
26.6 26.6
<.01 NS
Male Female
132 132
2245a>k l795a,k
217lb,l 1728°.'
2188b.l 1760abc,kl
2182b,l 1773ab.kl
2190b,l 173lbc,l
13.3 13.3
<.01 <.01
Sex
1 Dec 4
Male Female
2 Mar
Average
' ' Mean values within a row not sharing a common superscript differ significantly (P<.05). k1 ' Mean values within a row not sharing a common superscript differ significantly (P<.01). 1
Number of observations in each mean.
2
Standard error calculated from the error term of the analysis of variance.
3
Statistical level of significance of difference.
4
Month birds were processed.
nearly identical. However, in the relative order of male size, they ranged from heaviest in trial 1 to lightest in trial 2. When male and female plant weights were
c o m b i n e d , differences between crosses were significant ( P < . 0 1 ) in all trials (Table 2). The change in weight from the 56-day weighing t o the plant weight at 57 days is expressed as a
TABLE 2. Plant weight of broilers at 5 7 days expressed in grams and as a percentage of 56-day weight (data for both sexes combined)
Observations 1
Trial 1 Dec 4
66
Cross H X II
H X HN
HX S
RX H
R X AA
SE 2
P3
1957ab,k
1852d,m 96.56
1986a.k 96.49
1873cd,lm
1926bc,kl
96.40
96.45
18.0 .191
<.01 NS
96.745 2 Mar
66
2127a'k 98.10
2035bc,l 98.54
1991 c >' 97.40
2055b.1 97.75
2029bc.1 98.01
18.2 .191
<.01 NS
3 June
66
2080a.k 96.51
2O06 b ,l 97.34
2003b,l 97.38
2031ab.kl 97.46
2022b,kl 97.26
18.8 .191
<.01 NS
1919ab,kl
1905b.kl 96.46
1920ab.kl 96.73
1963a.k 96.38
1866b,l 96.61
18.7 .191
<.01 NS
1950°.! 97.23
1975bc,l
198lb,l 97.00
196lbc,l 97.08
9.4 .096
<.01 NS
4 Sept
66
96.73 Average
132
2021a>k 97.02
97.00
' ' ' Mean values within a row not sharing a common superscript differ significantly (P<.05). ' ' Mean values within a row not sharing a common superscript differ significantly (P<.01). 1
Number of observations in each mean.
2
Standard error calculated from the error term of the analysis of variance.
3
Statistical level of significance of difference.
4
Month birds were processed.
5
Plant weight divided by 56 day-on-feed weight X 100.
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HX H
Trial
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MERKLEYETAL.
crosses (Table 3) represents a difference of 1.8 g in liver weight. Lipid content of the livers, which was not determined, could be one factor possibly influencing the liver yields. The difference in heart weights among crosses, shown in Table 3 as percentages of plant weight, was significant (P<.01). The range of .06 percentage points between the H x H and R x H crosses represents an actual difference of 1.2 g in heart weight. The yield of the abdominal fat pad was significantly (P<.01) affected by cross, sex, and trial (Tables 3 and 4). Table 3 shows the significant difference in overall yield of abdominal fat between crosses. The difference between the H x H and R x H crosses of .38 percentage points represents an actual difference of 7.7 g of abdominal fat. Female birds (Table 4) had a much larger percentage of abdominal fat than did males of the same cross. The great variation in the amount of abdominal fat between trials is not unexpected, since the caloric content of the diet was not adjusted among flocks for changes in seasonal temperatures. If only a portion of the abdominal fat that had an average weight of 70 g was lost during processing and not included in the commercial
TABLE 3. Commercial yields as percentage of plant weight (data from both sexes and four trials combined)
(Cross Parts
HX H
H X UN
HX S
RX H
RX AA
P1
Fresh eviscerated carcass
65.36 2 ±.109 3.72a,k ±.056
65.40 ±.109 3.45bc,lm ±.056 1.73ab,kl ±.011
65.47 ±.109
65.60 ±.109
65.32 ±.109
NS
Abdominal fat pad
1.76a>k ±.011
Liver Gizzard
1.33 ±.017
Heart Neck Total
3.5lW klm ±.056 1.70bc ,1m ±.011
e m
3.34 ' ±.056
b kl
1.67c>m ±.011
3.56 > ±.056 l,69c,lm ±.011
.55a.k ±.008
1.35 + .016 .53ab,kl ±.008
1.31 ±.016 _5lbc,lm + .008
1.34 ±.017 .49c,m + .008
1.35 ±.016 .50C,m + .008
6.13 ±.042
6.15 ±.043
6.18 ±.042
6.11 ±.042
6.22 ±.042
78.85
78.61
78.68
78.55
78.64
' ' Mean values within a row not sharing a common superscript differ significantly (P<.05). ' ' Mean values within a row not sharing a common superscript differ significantly (P<.01). 1
Statistical level of significance of difference.
2
Means ± SE for 264 observations.
<.01 <.01 NS
<.01 NS
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percentage (plant weight/56-day weight X 100) in Table 2. There were no differences in this change in weight among crosses or sexes within each trial. The range in the average yield of the live plant weight for all crosses was from 96.53% in trial 1 to 97.96% in trial 2. This statistically significant (P<.05) difference among trials may be the result of ambient temperature during the period of feed withdrawal and transportation to the processing plant. The fresh eviscerated carcass weight (Table 3) expressed as a percentage of the plant weight was not significantly influenced by cross or sex. The flocks processed in March and June had an average fresh carcass yield without giblets (WOG) of 64.3 and 65.1%, respectively. The flocks processed in December and September had a 66.1 and 66.5% fresh eviscerated carcass yield (WOG). These yield percentages are based on a fresh carcass weight and not a water chilled carcass weight. The difference in yield among trials was significant at the 1% level. The yield of gizzards or necks among crosses or sexes was not significantly different. The yield of livers was significantly (P<.01) influenced by the cross of the bird. The range of .09 percentage points between the H X H and R X H
BROILER EVISCERATED AND COMPONENT PARTS YIELDS TABLE 4. Seasonal variation in yield of abdominal fat pad expressed as a percentage of plant weight (data from crosses combined) Sex Male
Female 1
1 Dec2
2.76e.r ±.071
3.51 c > m ±.071
2 Mar
3.13d,P ±.071
±.071
3.17d,nP ±.071
3.96W ±.071
3.40C,mn
4.23a.k ±.071
3 June 4 Sept
3.99b,kl
±.071
i bcdc ' ' ' ' Mean values not sharing a common superscript letter differ significantly (P<.05). k,l,m,n,p,r.. , , . Mean values not sharing a common superscript letter differ significantly (P<.01). 1 Means ± SE of 165 observations. 2
Month birds were processed.
yields, t h e accumulative effect on returns from saleable p r o d u c t would be noticeable. When t h e yields are totaled for each cross w i t h o u t including t h e abdominal fat, H X H birds d r o p p e d from the first t o fourth place in
t h e relative order of yield, and R X H birds increased from t h e lowest t o t h e highest in total percentage of yield. Although t h e percentage of fresh eviscerated carcass weights did n o t differ significantly a m o n g crosses, t h e relative yields of parts a m o n g crosses differed. Both male and female broilers exhibited highly significant ( P < . 0 1 ) differences in t h e percentage of breast, wings, and legs between crosses (Table 5). Differences in t h e percentage of yield of thighs were significant at t h e 5% level for b o t h sexes. The influence of sex in t h e yield of all five parts was highly significant ( P < . 0 1 ) when d a t a from t h e five crosses were c o m b i n e d . T h e relative yield of breast and back was greater in female broilers t h a n in male. Conversely, the relative yield of legs and thighs was greater in the males. When data from t h e four trials and b o t h sexes were c o m b i n e d (Table 6), all five parts had significant differences in t h e relative yield a m o n g strains. T h e Ross crosses (R X H, R X A A ) had significantly ( P < . 0 5 ) larger p r o p o r t i o n of breast t h a n the H u b b a r d crosses (H X H, H X HN, H X S). The opposite was true for t h e relative yield of legs. T h e H u b b a r d crosses had a larger p r o p o r t i o n of legs t h a n did t h e Ross crosses. T h e difference in t h e relative yield of backs among crosses was significant at t h e 5% level when data from b o t h
TABLE 5. Percentage of yield of individual parts of eviscerated male and female broiler carcasses^ Cross H X HN
H X S
RX H
R X AA
SE 2
p3
27.22c.m 28.36 '
27.32C,m 28.09b>cl
28.20a>k 28.66a.k
27.73b.' 28.72a'k
.104 .104
<.01 <.01
24.67 25.19
24.56 24.94
24.74 25.21
24.49 24.98
.096 .096
NS NS
Male Female
13.34W 13.50a,k
13.59a'k 13.48a.kl
13.l7c,lm b 1 3 29 ,m
13.15c.m 13.39ab'kl
24.61 24.95 13.22 b c,lrn 1 3 30b,lm
.050 .050
<.01 <.01
Legs
Male Female
16.50ab,k 15.41a.k
16.54ab.k 15.46ak
16.58 a > k 15.34a>k
16.25C 1 15.27ab.kl
16.37bc.kl 15.08b,l
.067 .067
<.01 <.01
Thighs
Male Female
18.01ab 17.86bc
18.07ab 17.76bc
18.16a 18.08a
17.90b 17.71c
18.08ab 17.93ab
.073 .073
<.05 <.05
Parts
Sex
H X H
Breast
Male Female
27.48C,lm
Back
Male Female
Wings
28.04C
1
b kl
' ' Mean values within a row not sharing a common superscript differ significantly (P<.05). ' ' Mean values within a row not sharing a common superscript differ significantly (P<.01). ' Each mean derived from 132 observations from the combined data of the four trials. 2
Standard error calculated from the error term of the analysis of variance.
3
Statistical level of significance of difference.
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Trial
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MERKLEYETAL. TABLE 6. Percentage of yield of individual parts of eviscerated broiler carcasses
Parts
Observations1
Breast
Cross p2
H X HN
HX S
RX H
R X AA
264
27.76 b -' ±.073
27.79°.' ±.074
27.70b>' ±.073
28.43 a > k ±.074
28.33 a > k + .073
<.01
Back
264
24.93 a b ±.068
24.75 a b ±.068
24.97 a + .068
24.73 b ±.068
24.78 a b ±.068
<.05
Wings
264
13.42 b > k ±.035
13.54 a . k + .035
13.23°.' + .035
13.27 c .' + .035
Legs
264
15.96 a . k ±.047 17.94bc,kl ±.052
16.00 a . k ±.047 17.92bc,kl ±.052
15.96 a > k ±.047
15.76b. 1 ±.047
13.26c>' ±.035 15.72^,1 + .047
Thighs
a
264
a k
18.12 . ±.052
c
17.81 .' ±.052
<.01 <.01
ab kl
18.00 * + .052
<.01
' ' Mean values within a row not sharing a common superscript differ significantly (P<.05). ' Mean values within a row not sharing a common superscript differ significantly (P<.01).
1
Each mean + SE derived from 264 observations from the combined data of both sexes and four trials.
2
Statistical level of significance.
sexes were combined (Table 6). T h e H X S carcasses had t h e largest yield of backs and thighs. T h e opposite was true for t h e R x H carcasses. A difference in t h e relative yield of any part a m o n g crosses of .20 percentage points represents an actual weight difference of a p p r o x i m a t e l y 2.6 g. When t h e results of various authors reported in the literature are c o m p a r e d , adjusting for t h e influence of diets, m a n a g e m e n t , environment, and m e t h o d s used in processing is difficult. We might assume after reviewing t h e results of this study t h a t all crosses d o n o t require identical conditions for o p t i m u m p e r f o r m a n c e . T h e differences a m o n g trials in this s u t d y alone were significant for all factors r e p o r t e d . T h e purpose of this s t u d y was t o c o m p a r e the processed yields and t h e relative yield of t h e various broiler parts of five commercial crosses. Many statistically significant differences were s h o w n to exist a m o n g t h e five crosses. T h e i m p o r t a n c e a t t r i b u t e d t o these differences should be determined by e c o n o m i c values derived u n d e r commercial operation and n o t by the statistics of this s t u d y .
REFERENCES Bouwkamp, E. L., D. E. Bigbee, and C. J. Wabeck, 1973. Strain influence on broiler parts yields. Poultry Sci. 52:1517-1523. Carlson, C. W., W. W. Marion, B. F. Miller, and T. L. Goodwin, 1975. Factors affecting poultry meat yields. North Central Reg. Res. Publ. No. 226, South Dakota Exp. Sta., Brookings, SD. Duncan, D. B., 1955. Multiple range and multiple F test. Biometrics 11:1-42. Hayse, P. L., and W. E. Marion, 1973. Eviscerated yield, component parts, and meat, skin and bone ratios in the chicken broilers. Poultry Sci. 52: 718-722. Malone, G. W., G. W. Chaloupka, J. W. Merkley, and L. H. Littlefield, 1979. Evaluation of five commercial broiler crosses. 1. Grow-out performance. Poultry Sci. 58:509-515. Moran, E. T., H. L. Orr, and E. Larmond, 1970. Influence of strain on the yield of commercial parts from the chicken broiler carcass. Poultry Sci. 49:725-729. Singh, S. P., and E. O. Essary, 1974. Factors influencing dressing percentage and tissue composition of broilers. Poultry Sci. 53:2143— 2147. Snedecor, G. W., and W. G. Cochran, 1968. Statistical methods. Iowa State University Press, Ames, IA.
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HX H
G. W. MALONE and G. W. CHALOUPKA University of Delaware, Georgetown, Delaware 19947 (Received for publication August 1, 1979) ABSTRACT The eviscerated yields and carcass characteristics of five commercial broiler crosses were evaluated. In each of four trials, processed in December, March, June, and September, 33 birds from each cross and each sex were used. Individual live weights were recorded at 56 days of age, prior to feed withdrawal, and immediately before processing (plant weight). The fresh eviscerated carcass weight, neck, abdominal fat, liver, gizzard, and heart weights were evaluated as a percentage of the plant weight. The relative yields of parts, breast, back, wings, legs, and thighs were determined for both sexes of each cross. No significant differences were observed in the loss of weight from the 56 day to the plant weight between crosses in any trial. In all trials, differences in plant weights between crosses were statistically significant (P<.01) when weights for both sexes were combined. When data from the four trials were combined, the cross X trial interaction for plant weights was significant (P<.01). The fresh eviscerated carcass yields were not significantly influenced by the cross or sex of broilers in any trial. The amount of abdominal fat was the largest single significant (P<.01) source of variation among the commercial yield of broiler crosses. When cut into parts, carcasses from female broilers had a significantly (P<.01) greater proportion of breast and back than male carcasses. (Key words: viscerated yields, abdominal fat, parts yield, broiler crosses) 1980 Poultry Science 59:1755-1760 INTRODUCTION It is h u m a n nature t o m a k e comparisons. When we find m o r e t h a n one of anything, our curiosity compels us t o ask which is the fastest, the most economical, or the best suited for a particular need. In t h e poultry industry, with n u m e r o u s broiler crosses commercially available, it is of major economic i m p o r t a n c e to d e t e r m i n e the performance of these broilers. T h e yield of edible p r o d u c t after processing is the final factor u p o n which an integrated c o m p a n y can calculate its efficiency and cost of p r o d u c t i o n . Factors affecting t h e yield of p r o d u c t obviously c o n t r i b u t e significantly to the profit or loss a c o m p a n y realizes. Because a large volume of processed broilers are m a r k e t e d in a further processed or cut-up form, yield of the various parts is also very i m p o r t a n t in evaluating t h e performance of a particular cross of broiler. Mo ran et al. ( 1 9 7 0 ) assessed die variation enc o u n t e r e d in t h e p r o d u c t i o n and processing of
White Rock and Cornish breeds with their reciprocal crosses. These authors r e p o r t e d better growth and feed conversion by the t w o crosses than by either breed alone. The Cornish male x White R o c k female had t h e best growth and feed conversion. Moran et al. ( 1 9 7 0 ) reported n o substantial influence of breed on t h e dressing performance or yield of commercial cuts from any of t h e chilled carcasses. Hayse and Marion ( 1 9 7 3 ) d e t e r m i n e d t h e eviscerated yield a n d c o m p o n e n t parts for b o t h sexes of a single breed at 8 weeks of age. They concluded that the relative yield and percentage of the various parts had n o t changed appreciably from t h a t r e p o r t e d in t h e ptevious 2 0 years. What had changed was a reduction in t h e m a r k e t age from 10 t o 8 weeks. B o u w k a m p et al. ( 1 9 7 3 ) studied t h e strain influence on t h e yield of broiler parts witli H u b b a r d X A r b o r Acre and Vantress X A r b o r Acre crosses. They r e p o r t e d a larger yield of
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US Department of Agriculture, Science and Education Beltsville, Maryland 20705
1756
M E R K L E Y ET AL.
PROCEDURES
Five commercially available broiler crosses were selected for the study. These crosses were: Hubbard (d) X Hubbard (9) (H X H) ; Hubbard (d) X HN (?) (H X HN); Hubbard (d) x Shaver (9) (H x S) ; Ross (d) X Hubbard (9) (R x H) ; and Ross (d) X Arbor Acre (9) (R X AA). In each of the four trials conducted, an effort was made to obtain eggs from at least two breeder flocks of the same age per cross. The eggs were hatched and the birds reared according to standard practices as described by Malone et al. (1979). Triplicate pens of 175 birds (743 cm 2 /bird) were used for each sex of the five crosses. When the birds reached 56 days of age, a representative sample was randomly selected from each of the 30 pens. Birds exhibiting obvious deformities or grossly abnormal weight were rejected. A final sample of 11 broilers from each pen were wing banded, weighed, and placed in a holding pen with feed and water available ad libitum. The feed and water were withdrawn approximately 10 hr before slaughter. The following day (57 days of age) the birds were placed in coops according to the pens from which they were originally removed and processed by the coop in a predetermined order to minimize the effect of holding time upon the yield data. Birds were processed in December, 1975, and March, June, and September, 1976, for trials 1, 2, 3, and 4, respectively.
As birds were removed from the coops for processing, individual weights (plant weights) were obtained. The 3 30 birds used in each trial were processed within a 4-hr period, and withdrawal time ranged from 10 to 14 hr. Birds were hung on shackles, immobilized with electrical stunning, and killed by the modified Kosher method. After a 90-second bleed time, they were scalded at 60 C for 90 sec in a rotating batch scalder. A centrifugical batch-type picker (90 sec) was used for feather removal. The heads and shanks were removed, and the modified New York Dressed carcasses were iced down overnight to facilitate the removal and weighing of the abdominal fat pad. The following morning the birds were eviscerated, and the fresh eviscerated carcass, abdominal fat pad, liver, gizzard, heart, and neck weights were recorded. The carcass weight was obtained with the lungs removed and the kidneys intact. The preen gland was not removed and is included in the back weights. The weight of the abdominal fat pad included all fat from around the gizzard and the abdominal cavity. Gizzards were weighed after peeling. Hearts were weighed without further trimming of attached vessels or removal of clotted blood. Eviscerated carcasses were iced down until the following day when che five major parts (breast, back, wings, legs, and thighs) were weighed. In each trial, one person made all of a particular type of cut with a knife. The wings were separated from the carcass at the shoulder leaving as much meat as possible on the breast. The backs contained both the gluteus muscle (oyster) and the pelvic meat. The breast was separated from the back at the shoulder and along the junction of the vertebral and sternal ribs. The percentages of the individual parts are based upon the combined weight of the parts obtained after cutting. Analysis of variance (Snedecor and Cochran, 1968) and Duncan's multiple range test (1955) were used to determine the significance of mean differences. RESULTS A N D DISCUSSION
Plant weights of the male and female birds in each trial are presented in Table 1. Differences were significant (P<.05) in the live weights among crosses in all four trials with the exception of the females in trials three and four. The cross X trial interaction for plant weights was significant (P<.05). For instance, in trials 1 and 2, the weights of the H X S males were
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breast and back and a smaller yield of wings and legs from the Hubbard offspring. Singh and Essary (1974) determined the influence of age and sex on the dressing percentage of broilers. Dressing percentages were similar between sexes for broilers of the same age. However, values were significantly (P<.05) different among broilers of different ages when values for sexes were combined. Further reference to this subject can be found in the detailed bulletin by Carlson et al. (1975). The purpose of this study was to obtain information on the fresh eviscerated carcass yields, the percentage of parts from five commercial crosses, and the variations in yields among four seasonal flocks. This information might be useful in evaluating efficiency and maximizing profits under commercial conditions. The study was conducted in conjunction with another reported by Malone et al. (1979) concerned with evaluating the grow-out performance of the same five commercial broiler crosses.
BROILER EVISCERATED AND COMPONENT PARTS YIELDS
1757
TABLE 1. Plant weight of male and female broilers at 56 days (g) Cross
Observations 1
H X HN
H X S
RX H
R X AA
SE 2
P3
33 33
2158a.k 1757ab,kl
2050b,l 1655C1
2187a.k 1785a.k
2047b,l 1698bc,kl
2136a.kl 1716abc,kl
25.4 25.4
<.01 <.01
Male Female
33 33
2368a.k 1886a.k
2287b,kl 1783be,kl
2180C1 180iabc,kl
2256 b <:,l 1853ab-kl
2293ab.kl 1766C1
25.7 25.7
<.01 <.01
3 June
Male Female
33 33
2320a 1832
2226b 1786
2242ab 1763
2215b 1824
2280ab 1764
26.6 26.6
<.05 NS
4 Sept
Male Female
33 33
2134ab,kl
2l2lbc,kl
2l42ab,kl
1705
1690
1691
2209 a >k 1718
2052C1 1679
26.6 26.6
<.01 NS
Male Female
132 132
2245a>k l795a,k
217lb,l 1728°.'
2188b.l 1760abc,kl
2182b,l 1773ab.kl
2190b,l 173lbc,l
13.3 13.3
<.01 <.01
Sex
1 Dec 4
Male Female
2 Mar
Average
' ' Mean values within a row not sharing a common superscript differ significantly (P<.05). k1 ' Mean values within a row not sharing a common superscript differ significantly (P<.01). 1
Number of observations in each mean.
2
Standard error calculated from the error term of the analysis of variance.
3
Statistical level of significance of difference.
4
Month birds were processed.
nearly identical. However, in the relative order of male size, they ranged from heaviest in trial 1 to lightest in trial 2. When male and female plant weights were
c o m b i n e d , differences between crosses were significant ( P < . 0 1 ) in all trials (Table 2). The change in weight from the 56-day weighing t o the plant weight at 57 days is expressed as a
TABLE 2. Plant weight of broilers at 5 7 days expressed in grams and as a percentage of 56-day weight (data for both sexes combined)
Observations 1
Trial 1 Dec 4
66
Cross H X II
H X HN
HX S
RX H
R X AA
SE 2
P3
1957ab,k
1852d,m 96.56
1986a.k 96.49
1873cd,lm
1926bc,kl
96.40
96.45
18.0 .191
<.01 NS
96.745 2 Mar
66
2127a'k 98.10
2035bc,l 98.54
1991 c >' 97.40
2055b.1 97.75
2029bc.1 98.01
18.2 .191
<.01 NS
3 June
66
2080a.k 96.51
2O06 b ,l 97.34
2003b,l 97.38
2031ab.kl 97.46
2022b,kl 97.26
18.8 .191
<.01 NS
1919ab,kl
1905b.kl 96.46
1920ab.kl 96.73
1963a.k 96.38
1866b,l 96.61
18.7 .191
<.01 NS
1950°.! 97.23
1975bc,l
198lb,l 97.00
196lbc,l 97.08
9.4 .096
<.01 NS
4 Sept
66
96.73 Average
132
2021a>k 97.02
97.00
' ' ' Mean values within a row not sharing a common superscript differ significantly (P<.05). ' ' Mean values within a row not sharing a common superscript differ significantly (P<.01). 1
Number of observations in each mean.
2
Standard error calculated from the error term of the analysis of variance.
3
Statistical level of significance of difference.
4
Month birds were processed.
5
Plant weight divided by 56 day-on-feed weight X 100.
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HX H
Trial
1758
MERKLEYETAL.
crosses (Table 3) represents a difference of 1.8 g in liver weight. Lipid content of the livers, which was not determined, could be one factor possibly influencing the liver yields. The difference in heart weights among crosses, shown in Table 3 as percentages of plant weight, was significant (P<.01). The range of .06 percentage points between the H x H and R x H crosses represents an actual difference of 1.2 g in heart weight. The yield of the abdominal fat pad was significantly (P<.01) affected by cross, sex, and trial (Tables 3 and 4). Table 3 shows the significant difference in overall yield of abdominal fat between crosses. The difference between the H x H and R x H crosses of .38 percentage points represents an actual difference of 7.7 g of abdominal fat. Female birds (Table 4) had a much larger percentage of abdominal fat than did males of the same cross. The great variation in the amount of abdominal fat between trials is not unexpected, since the caloric content of the diet was not adjusted among flocks for changes in seasonal temperatures. If only a portion of the abdominal fat that had an average weight of 70 g was lost during processing and not included in the commercial
TABLE 3. Commercial yields as percentage of plant weight (data from both sexes and four trials combined)
(Cross Parts
HX H
H X UN
HX S
RX H
RX AA
P1
Fresh eviscerated carcass
65.36 2 ±.109 3.72a,k ±.056
65.40 ±.109 3.45bc,lm ±.056 1.73ab,kl ±.011
65.47 ±.109
65.60 ±.109
65.32 ±.109
NS
Abdominal fat pad
1.76a>k ±.011
Liver Gizzard
1.33 ±.017
Heart Neck Total
3.5lW klm ±.056 1.70bc ,1m ±.011
e m
3.34 ' ±.056
b kl
1.67c>m ±.011
3.56 > ±.056 l,69c,lm ±.011
.55a.k ±.008
1.35 + .016 .53ab,kl ±.008
1.31 ±.016 _5lbc,lm + .008
1.34 ±.017 .49c,m + .008
1.35 ±.016 .50C,m + .008
6.13 ±.042
6.15 ±.043
6.18 ±.042
6.11 ±.042
6.22 ±.042
78.85
78.61
78.68
78.55
78.64
' ' Mean values within a row not sharing a common superscript differ significantly (P<.05). ' ' Mean values within a row not sharing a common superscript differ significantly (P<.01). 1
Statistical level of significance of difference.
2
Means ± SE for 264 observations.
<.01 <.01 NS
<.01 NS
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percentage (plant weight/56-day weight X 100) in Table 2. There were no differences in this change in weight among crosses or sexes within each trial. The range in the average yield of the live plant weight for all crosses was from 96.53% in trial 1 to 97.96% in trial 2. This statistically significant (P<.05) difference among trials may be the result of ambient temperature during the period of feed withdrawal and transportation to the processing plant. The fresh eviscerated carcass weight (Table 3) expressed as a percentage of the plant weight was not significantly influenced by cross or sex. The flocks processed in March and June had an average fresh carcass yield without giblets (WOG) of 64.3 and 65.1%, respectively. The flocks processed in December and September had a 66.1 and 66.5% fresh eviscerated carcass yield (WOG). These yield percentages are based on a fresh carcass weight and not a water chilled carcass weight. The difference in yield among trials was significant at the 1% level. The yield of gizzards or necks among crosses or sexes was not significantly different. The yield of livers was significantly (P<.01) influenced by the cross of the bird. The range of .09 percentage points between the H X H and R X H
BROILER EVISCERATED AND COMPONENT PARTS YIELDS TABLE 4. Seasonal variation in yield of abdominal fat pad expressed as a percentage of plant weight (data from crosses combined) Sex Male
Female 1
1 Dec2
2.76e.r ±.071
3.51 c > m ±.071
2 Mar
3.13d,P ±.071
±.071
3.17d,nP ±.071
3.96W ±.071
3.40C,mn
4.23a.k ±.071
3 June 4 Sept
3.99b,kl
±.071
i bcdc ' ' ' ' Mean values not sharing a common superscript letter differ significantly (P<.05). k,l,m,n,p,r.. , , . Mean values not sharing a common superscript letter differ significantly (P<.01). 1 Means ± SE of 165 observations. 2
Month birds were processed.
yields, t h e accumulative effect on returns from saleable p r o d u c t would be noticeable. When t h e yields are totaled for each cross w i t h o u t including t h e abdominal fat, H X H birds d r o p p e d from the first t o fourth place in
t h e relative order of yield, and R X H birds increased from t h e lowest t o t h e highest in total percentage of yield. Although t h e percentage of fresh eviscerated carcass weights did n o t differ significantly a m o n g crosses, t h e relative yields of parts a m o n g crosses differed. Both male and female broilers exhibited highly significant ( P < . 0 1 ) differences in t h e percentage of breast, wings, and legs between crosses (Table 5). Differences in t h e percentage of yield of thighs were significant at t h e 5% level for b o t h sexes. The influence of sex in t h e yield of all five parts was highly significant ( P < . 0 1 ) when d a t a from t h e five crosses were c o m b i n e d . T h e relative yield of breast and back was greater in female broilers t h a n in male. Conversely, the relative yield of legs and thighs was greater in the males. When data from t h e four trials and b o t h sexes were c o m b i n e d (Table 6), all five parts had significant differences in t h e relative yield a m o n g strains. T h e Ross crosses (R X H, R X A A ) had significantly ( P < . 0 5 ) larger p r o p o r t i o n of breast t h a n the H u b b a r d crosses (H X H, H X HN, H X S). The opposite was true for t h e relative yield of legs. T h e H u b b a r d crosses had a larger p r o p o r t i o n of legs t h a n did t h e Ross crosses. T h e difference in t h e relative yield of backs among crosses was significant at t h e 5% level when data from b o t h
TABLE 5. Percentage of yield of individual parts of eviscerated male and female broiler carcasses^ Cross H X HN
H X S
RX H
R X AA
SE 2
p3
27.22c.m 28.36 '
27.32C,m 28.09b>cl
28.20a>k 28.66a.k
27.73b.' 28.72a'k
.104 .104
<.01 <.01
24.67 25.19
24.56 24.94
24.74 25.21
24.49 24.98
.096 .096
NS NS
Male Female
13.34W 13.50a,k
13.59a'k 13.48a.kl
13.l7c,lm b 1 3 29 ,m
13.15c.m 13.39ab'kl
24.61 24.95 13.22 b c,lrn 1 3 30b,lm
.050 .050
<.01 <.01
Legs
Male Female
16.50ab,k 15.41a.k
16.54ab.k 15.46ak
16.58 a > k 15.34a>k
16.25C 1 15.27ab.kl
16.37bc.kl 15.08b,l
.067 .067
<.01 <.01
Thighs
Male Female
18.01ab 17.86bc
18.07ab 17.76bc
18.16a 18.08a
17.90b 17.71c
18.08ab 17.93ab
.073 .073
<.05 <.05
Parts
Sex
H X H
Breast
Male Female
27.48C,lm
Back
Male Female
Wings
28.04C
1
b kl
' ' Mean values within a row not sharing a common superscript differ significantly (P<.05). ' ' Mean values within a row not sharing a common superscript differ significantly (P<.01). ' Each mean derived from 132 observations from the combined data of the four trials. 2
Standard error calculated from the error term of the analysis of variance.
3
Statistical level of significance of difference.
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Trial
1759
1760
MERKLEYETAL. TABLE 6. Percentage of yield of individual parts of eviscerated broiler carcasses
Parts
Observations1
Breast
Cross p2
H X HN
HX S
RX H
R X AA
264
27.76 b -' ±.073
27.79°.' ±.074
27.70b>' ±.073
28.43 a > k ±.074
28.33 a > k + .073
<.01
Back
264
24.93 a b ±.068
24.75 a b ±.068
24.97 a + .068
24.73 b ±.068
24.78 a b ±.068
<.05
Wings
264
13.42 b > k ±.035
13.54 a . k + .035
13.23°.' + .035
13.27 c .' + .035
Legs
264
15.96 a . k ±.047 17.94bc,kl ±.052
16.00 a . k ±.047 17.92bc,kl ±.052
15.96 a > k ±.047
15.76b. 1 ±.047
13.26c>' ±.035 15.72^,1 + .047
Thighs
a
264
a k
18.12 . ±.052
c
17.81 .' ±.052
<.01 <.01
ab kl
18.00 * + .052
<.01
' ' Mean values within a row not sharing a common superscript differ significantly (P<.05). ' Mean values within a row not sharing a common superscript differ significantly (P<.01).
1
Each mean + SE derived from 264 observations from the combined data of both sexes and four trials.
2
Statistical level of significance.
sexes were combined (Table 6). T h e H X S carcasses had t h e largest yield of backs and thighs. T h e opposite was true for t h e R x H carcasses. A difference in t h e relative yield of any part a m o n g crosses of .20 percentage points represents an actual weight difference of a p p r o x i m a t e l y 2.6 g. When t h e results of various authors reported in the literature are c o m p a r e d , adjusting for t h e influence of diets, m a n a g e m e n t , environment, and m e t h o d s used in processing is difficult. We might assume after reviewing t h e results of this study t h a t all crosses d o n o t require identical conditions for o p t i m u m p e r f o r m a n c e . T h e differences a m o n g trials in this s u t d y alone were significant for all factors r e p o r t e d . T h e purpose of this s t u d y was t o c o m p a r e the processed yields and t h e relative yield of t h e various broiler parts of five commercial crosses. Many statistically significant differences were s h o w n to exist a m o n g t h e five crosses. T h e i m p o r t a n c e a t t r i b u t e d t o these differences should be determined by e c o n o m i c values derived u n d e r commercial operation and n o t by the statistics of this s t u d y .
REFERENCES Bouwkamp, E. L., D. E. Bigbee, and C. J. Wabeck, 1973. Strain influence on broiler parts yields. Poultry Sci. 52:1517-1523. Carlson, C. W., W. W. Marion, B. F. Miller, and T. L. Goodwin, 1975. Factors affecting poultry meat yields. North Central Reg. Res. Publ. No. 226, South Dakota Exp. Sta., Brookings, SD. Duncan, D. B., 1955. Multiple range and multiple F test. Biometrics 11:1-42. Hayse, P. L., and W. E. Marion, 1973. Eviscerated yield, component parts, and meat, skin and bone ratios in the chicken broilers. Poultry Sci. 52: 718-722. Malone, G. W., G. W. Chaloupka, J. W. Merkley, and L. H. Littlefield, 1979. Evaluation of five commercial broiler crosses. 1. Grow-out performance. Poultry Sci. 58:509-515. Moran, E. T., H. L. Orr, and E. Larmond, 1970. Influence of strain on the yield of commercial parts from the chicken broiler carcass. Poultry Sci. 49:725-729. Singh, S. P., and E. O. Essary, 1974. Factors influencing dressing percentage and tissue composition of broilers. Poultry Sci. 53:2143— 2147. Snedecor, G. W., and W. G. Cochran, 1968. Statistical methods. Iowa State University Press, Ames, IA.
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HX H