Conformation and Performance in Standardbred and Crossbred Broilers

Conformation and Performance in Standardbred and Crossbred Broilers (Received for publication November 4, 1950)

between the performance of the production strain and broiler strain of the New Hampshire breed and in certain crosses.

INTRODUCTION

W

I T H I N the last few years, considerable emphasis has been placed on the importance of producing high MATERIALS AND METHODS quality broilers with a minimum amount In January 1949, 100 day-old chicks of feed and in the shortest period of time. The birds which have been utilized to from each of the following breeds or meet this requirement have often been crosses were started: New Hampshires referred to as broiler strain chickens. To (production), New Hampshires (broiler), meet the needs of the specialty producer, Barred Rock males X New Hampshire strains supposedly superior in meat pro- females (broiler), New Hampshire males duction and egg production have been (broiler) X Barred Rock females, and standardbred Barred Rocks, except that developed. Factors such as rapid growth, rapid the lot involving Barred Rock males feathering, high feed efficiency, early XNew Hampshire females contained only maturity, body conformation, and egg 58 day-old chicks. Broiler stock involved production are desirable for egg produc- was from a nationally known breeder of tion and broiler production strains. Due New Hampshires known for their growth, to the interest shown in the performance feathering, and other broiler characterisof broiler production strains, and egg tics. The New Hampshire egg production production strains, a study was under- birds were from a nationally known taken to compare body conformation and Tennessee R.O.P. breeder of New Hampother selected factors between egg pro- shires who recently qualified 45 percent duction strains of New Hampshires, of the pullets started in R.O.P. All chicks broiler strains of New Hampshires, Barred were started and maintained for the first Rocks, and crosses involving Barred six weeks in electrically heated battery Rocks and broiler strains of New Hamp- brooders, after which time they were placed in a continuous type brooder shires. house under electrically heated brooders. The object of this experiment was to Chicks were vaccinated with a live-virus determine if significant differences exist type Newcastle disease vaccine at that Published with the approval of the Director of time. All chicks were fed the same ration Tennessee Experimental Station. and managed in a similar manner. * Now with Texas A & M College, College StaFeed consumption records were kept tion, Texas. 5S2

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E. O. ESSARY, G. J. MOUNTNEY* AND 0 . E . GoiT University of Tennessee, Agricultural Experiment Station, Knoxville

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BROILER CONFORMATION AND PERFORMANCE

and feed efficiency determined for each lot. at 4, 8, and 12 weeks. Chick weights were obtained at one day, 4, 8, and 12 weeks of age. The rate of feathering was determined at one day, 2, 8, and 12 weeks of age. The wing feather development was observed for the rate of feathering at one day of age,

graduated to a thousandth of an inch, were used in determining the shank length, body depth, keel length, and breast width of each bird similar to the method used by Jaap and Penquite (1938). The measurements were taken to the nearest hundredth inch. The pullets from the 5 lots were saved for future

Breed and strain

N.H. (Production)

N.H. (Broiler)

B.R.XN.H.

N.H.XB.R.

B.R.

Sex

Percent rapid feathering

Averag re weight per bird in lbs.

12 weeks

4 weeks

8 weeks

12 weeks

Male Female

76.6 100.0

.84 .75

1.9 1.6

3.7 2.9

Average

88.2

.80

1.7

3.3

Male Female

97.7 98.0

.83 .78

2.2 1.9

4.1 3.3

Average

97.8

.80

2.0

3.7

Male Female

100.0 100.0

.91 .78

2.3 1.9

4.5 3.4

Average

100.0

.87

2.1

4.0

Male Female

100.0 90.4

.88 .79

2.2 1.9

4.3 3.3

Average

97.9

.83

2.1

3.8

Male Female

97.6 100.0

.88 .78

2.1 1.8

4.1 3.2

Average

98.9

.82

1.9

3.6

according to the method used by Darrow and Warren (1944). At 2 and 8 weeks of age, the degree of feathering on the sides, back, and tail was determined. At 12 weeks the feathering on the sides and back was determined. Arbitrary grades indicating rapid and slow feathering were established. Only those individuals showing good tail development and complete feathering over the back and sides were classified as rapid feathering. At 12 weeks of age, Vernier calipers,

Average feed consumption per bird

Feed efficiency

Lbs. broiler per 100 lbs. feed

12 weeks

12 weeks

12 weeks

13.8

4.3

23.9

14.8

4.1

25.0

13.9

3.4

28.7

14.1

3.7

26.9

12.9

3.7

27.9

comparisons. Twenty cockerels from each of the 5 lots were selected at random, processed, and dejointed. The dressing percent and the percent yield of the carcass consisting of the wings, breast, legs, back, and offal were determined. All weights were in grams. RESULTS

Rate of feathering.—The NH broiler strain tended to have a larger percentage of rapid feathering birds than did the

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TABLE 1.—Feathering, weight, and feed efficiency

554

E. O. ESSARY, G. J. MOUNTNEY AND O. E. GOFF

weeks), while the males of the B R X N H cross were the heaviest birds of any groups with an average weight of 4.5 lbs. at 12 weeks. The five .breeds or crosses were broken down into male and female groups and an analysis of variance run on the 12 week weights. Highly significant differences existed. Least significant differences were then calculated between these 10 groups. In all but two cases significant differences between the males and females were obtained at the five percent level. Feed efficiency.—As usual, all lots made more efficient use of their ration when they were from 1 to 4 weeks of age and 4 to 8 weeks than from the 8 to 12 week period. The more rapid growing birds required fewer pounds of feed to produce 1 pound of gain than did those growing at a slower rate. The B R X N H required 3.4 lbs. of feed to produce 1 pound of gain for the 12 week period, which was 0.3 lb. less feed than was required by the N H X B R and the Standardbred BR. The NH production strain was the least efficient in feed utilization as they required 4.3 lbs. of feed to produce 1 pound of gain. Expressed in terms of pounds of chicken produced per 100 lbs. of feed, the B R X N H produced 28.7 lbs. of meat per 100 lbs. of feed, the BR 27.9, N H X B R 26.9, the NH (broilers) 25.0, while the NH (production) produced 23.9 lbs. of meat per 100 lbs. of feed (Table 1). The poor efficiency and slower rate of growth of the NH production strain is a Criticism aimed at stock not selected for performance in the broiler house. Mortality.—Negligible differences existed in percent mortality between the various lots through 8 weeks of age. The mortality through 12 weeks appeared to be reasonable and within the expected range. The mortality through 12 weeks of

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NH production strain (Table 1). In the B R X N H cross, no males were rapid feathering at 1 day and 2 weeks, but at 12 weeks all birds were classified as rapid feathering. Except in the NHXBR, the females in all groups at all ages had a larger percentage of rapid feathering birds than the males. At 12 weeks of age, the B R X N H had the highest percentage of birds showing rapid feathering (100 percent), and the NH production strain the least (88.2 percent). The percent of birds exhibiting rapid feathering at 12 weeks of age in all lots was superior to the percent of rapid feathering in the NH production strain. In studying the rate of feathering, many of the BR showed complete feathering over the back and sides at 12 weeks of age, but failed to have well developed tails. Average weight.—The average weight of the NH broiler strain chicks at 8 and 12 weeks of age was greater than the NH production strain. At 12 weeks of age the B R X N H chicks were the heaviest (4 lbs.), followed by the N H X B R (3.8 lbs.). For several years, commercial broiler producers have used these breeds in crosses to secure greater gains in their chicks. It should be pointed out that chicks from each of these crosses were superior in weight to the same strain of stock that went into the cross; NH (broiler 3.7 lbs.), BR (3.6 lbs.). All lots grew at a more rapid rate than did the production strain of NH chicks. As expected, the males in each group weighed more than the females with the males from B R X N H cross reaching an average weight of 4.5 lbs. at 12 weeks (Table 1). The average weight of the B R X N H was heavier at 4, 8, and 12 weeks than any other breed or cross. Lightest average weights of all groups were those of the NH production strain (3.3 lbs. at 12

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BROILER CONFORMATION AND PERFORMANCE

NH (production strain) had the smallest minimum depth of body (4.38 in.). Each of the two crosses had a body depth greater than either of the parent breeds. There was a significant difference in the width of breast between lots. The B R X N H had the widest average breast width (1.58 in.) and the N H X B R the narrowest (1.48 in.). There was a sig-

TABLE 2.—Measurements of live birds in inches at 12 weeks Breed and strain

Sex

Shank length

Body depth

Breast width

Keel length

N.H. (Production)

Male Female

4.45 3.90

4.57 4.18

1.57 1.52

3.92 3.60

Average

4.17

4.38

1.54

3.76

Male Female

4.52 3.97

4.65 4.22

1.61 1.52

4.10 3.77

Average

4.23

4.42

1.56

3.92

Male Female

4.80 4.17

4.81 4.47

1.59 1.57

4.17 4.00

Average

4.60

4.70

1.58

4.11

Male Female

4.68 4.14

4.71 4.32

1.48 1.49

4.10 3.89

Average

4.41

4.52

1.48

3.99

Male Female

4.69 4.08

4.74 4.31

1.58 1.41

4.25 4.00

Average

4.35

4.50

1.49

4.11

N.H. (Broiler)

B.R.XN.H.

N.H.XB.R.

B.R.

longest shank (4.60 in.) and the NH (production) had the shortest shanks (4.17 in.). This is in agreement with Lerner (1946) and Wiley (1950) who found that the more rapid growing birds generally had a longer shank than the slower growing birds. The average shank length (4.41 in.) of the N H X B R was longer than the average of either of the parent breeds used in the cross, NH 4.23 in. and BR 4.35 in. (Table 2). The B R X N H had the greatest average minimum body depth (4.70 in.) which was highly significant. This measurement was taken when the bird exhaled. The

nificant difference at the 5 percent level when males and females of different lots were compared, and the breast width between the B R X N H and N H X B R crosses. It is of interest to note, however, that no significant differences existed between breast width of the two NH strains. The B R X N H and BR had the longest keel lengths (4.11 in.) which was highly significant. The shortest keel length was" the NH production strain (3.76 in.). The keel length of the B R X N H (4.11 in.) equaled the keel length of the BR but was more than the keel length of the NH broiler strain (3.93 in.). The keel

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age for the various strains and crosses were NH (broiler) 6 percent, NH (production) 4 percent, B R X N H 1.7 percent, NH XBR 1 percent, and BR 7 percent. It is noted that the crosses gave greater livability than did the other lots. Measurements.—There was a highly significant difference in shank length between lots. The B R X N H had the

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E. 0 . ESSARY, G. J. MOUNTNEY AND 0 . E. GOFF

of the legs, both crosses had heavier legs than did either of the parent breeds. There was a highly significant difference between the 5 lots in the weight of the back, ribs, and neck which were weighed as one unit. This unit in the BR X N H had a percentage of 18.5. These parts of the carcass, however, have the least sales value and would be considered less important in determining the value of the bird for broiler production.

TABLE 3.—Weights and percentage of the parts in relationship to the dressed carcass at 12* week Breed and strain N.H. (Production) N.H. (Broiler) B.R.XN.H. N.H.XB.R. B.R.

Dressed wt lbs.

Dressing percent

3.18 3.54 3.89 3.77 3.69

Wings Percent

Wtin gms.

Percent

88.0

153

10.6

254

17.6

86.3

167

10.4

288

17.8

88.3 89.2 88.9

180 173 166

10.2 10.1

327 315 313

18.7 18.4 19.5

9.9

Back, ribs, neck Offal and giblets

Legs

Breast

Wt.in gms.

Wt.in gms.

379

Percent 25.3

253

cent 17.5

384

Percent 29.0

417

26.6

287

17.8

400

27.4

481 456 436

27.2 26.6 26.0

326 303 301

18.5 17.7 17.9

442 453 429

25.4 27.2 26.7

Wt.in gms.

Per

Wt.in gms.

* Twenty cockerels in each lot except Barred Rock XNew Hampshire which had 19. One bird discarded because of large tumorous growth on viscera.

strain of NH had the largest percentage of wings (10.6); whereas, the BR had the lowest percentage (9.9). In the percentage of breast, the BR had 19.5 percent, the highest percentage of all lots, with both strains of N H showing the lowest percentages. The B R X N H and N H X B R had 18.7 and 18.4 percent of breast, respectively. This might indicate that a larger percent of breast could be obtained by crossing the broiler strain of NH with BR. However, breasts from the crosses did not equal the breast weight of the BR. Statistically, there was a highly significant difference between all lots in the percent of yield except in the breast weight. The B R X N H had the largest percentage of legs (thigh and drumstick, 27.2). The NH production strain had the lowest percentage (25.3). The N H X B R had a percentage of 26.6 which was equal to the NH broiler strain but higher than the BR. However, in the actual weights

The NH production strain contained the highest percentage of offal (29.0) with the B R X N H containing the lowest percentage (25.4). These offal percentages, however, would have little value in measuring meat qualities of the bird, but is of immense importance in evaluating the yield of edible meat. DISCUSSION

Breeders of egg production flocks have been confronted with the usually poor performance of their stock for meat production. The poultryman is often disappointed in the performance of egg production strains when used for broiler production. It is often stated and often true that chickens bred for high egg production lack desirable body conformation, rapid feathering, desirable growth rate, and high feed efficiency necessary for profitable meat production by broiler producers. On the other hand, the breeder endeavoring to produce desirable broiler

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length of either cross was longer than the keel length of the NH broiler strain. Dressing percent and percent yield of various parts of the carcass.—There was little difference in the dressing percentage between the 5 lots (Table 3). The lowest dressing percentage (86.3) was in the broiler strain of NH and the highest (89.2) in the N H X B R cross—a variation of 2.9 percent. It should be noted that the production

BROILER CONFORMATION AND PERFORMANCE

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stock often possesses birds that lay at a maturity, body size, variation in body low annual rate. Often the flock owner weight, egg production, egg weight, and has not received just compensation for feed efficiency are some of the factors to producing hatching eggs for broiler produc- be studied. tion since hatcherymen often pay the SUMMARY same price per dozen regardless of the Five lots of day-old chicks, involving production rate of the flock. Broiler type 458 individuals from two breeds and birds may be inferior in egg production certain crosses, were started in order to when used on the general farm or when study their performance to 12 weeks of placed in competition with so-called egg age. production strains. The cross involving the BR male and Many poultrymen feel that high or NH female (broiler strain) was superior desirable egg production and superior in weight, percentage of rapid feathering, performance in the production of meat dressed weight, shank length, body depth, are impossible to be developed in one and keel length. Feed utilization for this strain. A breed or cross satisfactory for cross was the most efficient of all lots. both egg and meat production would be By weight, the egg production strain of immense benefit to the poultry inof NH had the highest percentage of dustry. In such stock, surplus pullets and wings (10.6), but the lowest percentage of cockerels would not be discriminated legs (thighs and drumsticks, 25.3). This against on the market. Neither would the strain produced 23.9 lbs. of meat per 100 owner of a broiler strain of birds be exlbs. of feed; it possessed the largest perpected to sell his hatching eggs at a price centage of slow feathering birds. less than his efforts and low egg producThe BR had the highest percentage of tion warrants. breast (19.5) but the lowest percentage This study was undertaken to deter- of wings (9.9) when measured in terms of mine if significant difference existed in the weight. performance between production strain, The NH broiler strain gave results broiler strain, and limited crosses between superior in several respects to the NH them. Although certain significant dif- production strain. The B R X N H cross ferences did exist, data are presented was heavier at 12 weeks of age and showing similarity between lots indicating showed greater feed efficiency than did that production strain in birds possess the standard breeds. some factors desired in broiler-stock. The REFERENCES reverse is also true. For example, 88.2 percent of the NH production strain were Darrow, Merritt I., and D. C. Warren, 1944. The influence of age on expression of genes controlling rapid feathering at 12 weeks of age. On rate of chick feathering. Poultry Sci. 23:199-212. the other hand, the crosses and broiler Jaap, George R., and Robert Penquite, 1938. Criproduction type stock possess a desirable teria of conformation in market poultry. Poultry growth rate, and rapid feathering, which Sci. 17:425-430. are desirable factors in a production Lerner, I. M., 1937. Shank length as a criterion of inherent size. Poultry Sci. 16: 213-215. strain. Wiley, William H., 1950. The influence of egg weight Pullets from the five lots have been on the prehatching and post-hatching growth selected so that their performance in the rate in the fowl. III. Shank-length body weight laying house might be compared. Age at ratios. Poultry Sci. 29: 650-609.