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CROSSBREEDING BEEF CATTLE

value of crossbreeding for commercial cattle production shown in long-time research at Black Belt Substation
BULLETIN 433 MAY 1972

00

-

Agricultural Experiment Station AUBURN UNIVERSITY
Auburn, Alabama

E. V. Smith, Director

CONTENTS Page
EXPERIMENTAL PROCEDURE ------------4

A nalysis of Data -- ---RESULTS AND DISCUSSION

-- -- -- -- -- -- -- -- -- -- ------------

- 6 -7

Pe rio d I -- - - - - - - - - - - - - - - - - -- - - - - - - - - - - - - - - - - - - - 7 Period II-------- -- -- - --8--

Pe riod III - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 9 Period IV Period V -------------------SUMM ARY LITERATURE

11--------------------------CITED -----------------------------------

12 12-----

18-----------------

20

A P P EN DIX - - - - - - - - - - - - - - - - - - - - - -- - - - - - - - - - - - - - - - - - - - - -2 3

M ethods

of Analysis --------------------------------

26

ACKNOWLEDGMENTS The authors acknowledge contrihutions of the late
Kelly during initial stages of this study, and of J. A. McGuire for his assistance in analysis of the data.

K. G. Baker and the late W. B.

FIRST PRINTING

5M, MAY 1972

CROSSBREEDING BEEF CATTLE
Value of Crossbreeding for Commercial Catle Production Shown in Long-Time Research at Black Belt Substation
J. C. COLLINS, T. B. PATTERSON, W. M. WARREN, L. A. SMITH and HAROLD GRIMES'

THE

PHENOMENON OF HETEROSIS, or "hybrid vigor," has long been observed in domestic plants and animals. Plant and animal breeders now recognize and accept crossbreeding as a method of improving production. Nearly all corn and a high percentage of many other crops produced in the United States are the result of crossing inbred lines. It has been estimated that three-fourths of the market hogs produced in the United States are crossbred. The poultry industry has made great improvement in broiler growth rate and feed efficiency by using highly specialized hybrids and, to a lesser extent, hybrids layers have been used for the production of eggs. Commercial crossbreeding of beef cattle has been centered in the Southern United States. In the Gulf Coast Region, Brahman bulls have been crossed with native and British breed cows for improved production and greater tolerance to heat and insects. British breed bulls have been used in a rotational backcross program, or as a third breed, with the part-Brahman cows. Crossbred females have been highly productive, but perhaps of greatest importance is the reproductive efficiency associated with crossbreeding. Several workers reported higher calving rates as a result of crossing two breeds (5,11,31,34,38). Others have shown that crossbred females drop and wean a significantly
'Former Instructor, Department of Animal and Dairy Sciences, now Leader, Extension Animal Science Department, Mississippi State University; Professor, Department of Animal and Dairy Sciences; Head Professor, Department of Animal and Dairy Sciences; Superintendent, Black Belt Substation; Assistant Superintendent, Black Belt Substation.

4

ALABAMA AGRICULTURAL EXPERIMENT STATION

higher percentage calf crop than straightbred females (5,22,30,33, 34,37,38). Many workers have reported that crossbred calves were heavier at birth (5,7,8,10,11,13,14,16,20,21,24,31,35). That three-breed cross calves were heavier than either two-breed or purebreds has been shown by others (15,35). Crossbred calves from purebred cows were found to be heavier at weaning than purebreds (1,2,8,11,13,16,20,1,31), and threebreed cross calves heavier than either purebred or two-breed calves (11,15,35). Largely because of heterotic effect in the crossbred dams, backcross calves were heavier than straightbreds at weaning (5,24,26,35). In general, crossbred calves gained faster post-weaning than did straightbred calves (5,17,36). However, the reverse was true for some specific crosses with weaning weights as heavy as or heavier than straightbred calves (3,4,17). Vogt et al. (36) reported that two-breed calves gained faster post-weaning than did three-breed calves. Slaughter or feeder grades at weaning were found to be not significantly different among beef breeds and crosses unless the Brahman breeding of the calf exceeded 50 per cent (6,8,9,11,16, 24,30,31,34). Differences between purebred and crossbred carcass traits tend to be small and non-significant unless the trait is associated with weight (3,4,9,12,13,21,35). Throughout these crossbreeding studies, specific breed crosses occasionally resulted in exceptions to these general findings. EXPERIMENTAL PROCEDURE The data reported here were obtained from research at the Black Belt Substation, Marion Junction, Alabama. These investigations began with the records of calves born in the 1950 calving season and ended with the post-weaning performance records of steer calves born during the 1966 calving season. Foundation cows used were high grade Herefords. The crossbred cows were produced at the Substation by mating the foundation Hereford cows to Brahman, Shorthorn, and Angus bulls. Replacement heifers produced on the Substation were added as needed to maintain the experimental herds. To permit valid analyses, this study was divided into five periods.

CROSSBREEDING

BEEF CATTLE

5

Period I. A 6-year period (1950-55) in which Angus bulls were mated to Hereford and Brahman-Hereford cows. Period II. The 4-year period (1952-55) in which Angus bulls were mated to Hereford, Brahman-Hereford, and ShorthornHereford cows. Period III. A 4-year period (1956-59) in which Hereford bulls were mated to Hereford, Brahman-Hereford, and ShorthornHereford cows. This period extended into Period IV. Period IV. A 5-year period (1956-60) in which Hereford cows were randomly assigned to be mated to either Angus or Hereford bulls. Brahman-Hereford cows were bred to the same Hereford bulls. Period V. An 8-year period (1959-66) in which Hereford bulls were mated to Hereford, Angus-Hereford, and Hereford x (Brahman-Hereford) cows and Angus-Hereford cows were backcrossed to Angus bulls. Throughout this investigation, each calf was numbered and each male castrated within 24 hours after birth. Sex, birth weight, birth date, and dam's number were recorded. During periods I, II, III, and IV, three weaning dates were selected each year so that the average weaning age of each group of calves would be approximately 250 days. All calves were individually weighed at weaning. The project was revised in 1955, in a manner that allowed completion of Period III and at the same time initiated Period IV. Therefore, part of the data collected was common to both periods. Beginning with Period IV, slaughter grades were obtained on all calves at weaning. In Period V steer calves were continued on a post-weaning performance test on the ration shown in Appendix Table 1. After weaning calves were held in a small paddock for an adjustment period varying up to 24 days, during which time they were fed a limited amount of corn and cottonseed meal and johnsongrass hay ad libitum. Following the adjustment period, the steers were fed 5 pounds of corn per head daily on dallisgrass pasture. The actual weaning weight was used as the initial post-weaning test weight. Steers went from the pasture period to the feedlot for a finishing period averaging 144 days. The finished steers were slaughtered and carcass data obtained. These

6

ALABAMA AGRICULTURAL EXPERIMENT STATION

data included carcass weight, ribeye area, fat thickness, and USDA quality grade. Throughout the experiment heifers were bred to Angus bulls to calve as 2-year-olds. Data from 2-year-olds were included only in periods I and II, however, because in other periods some of the older cows were bred to Hereford bulls. Management practices for these heifers were as follows: (1) From weaning (July-August-September) through October, they were fed a daily ration of 3 pounds of crushed ear corn while on pasture. (2) During the winter months (November-February), they were fed daily 11/2 pounds of 41 per cent cottonseed meal, 21/2 pounds of crushed ear corn, and johnsongrass hay free choice (approximately 12 pounds). (3) Beginning in late January the heifers were bred to Angus bulls and given access to pasture for the spring and summer months. (4) As they began calving in November, they were fed johnsongrass hay free choice (approximately 20 pounds), 2 pounds of 41 per cent cottonseed meal, and 3 pounds of crushed ear corn daily. (5) Calves from 2-year-old heifers were creep fed. During the winter months brood cows, 3 years old and older, were fed 2 pounds of 41 per cent cottonseed meal per head daily plus johnsongrass hay ad libitum. Caley peas (wild winter) were grazed for approximately 50 days in early spring and permanent pasture, primarily dallisgrass and a small amount of white clover, from late spring until late fall. Salt was the only supplemental mineral provided. Calves were not creep fed. Analysis of Data The data were analyzed by periods using the least-squares procedures as described by Harvey (19). Corrections were made for age of dam effects on 250-day weaning weights. Because of small subclass numbers, least-squares constants for age of dam were calculated by pooling all data from periods I through V (Appendix Table 2). Year, sex of calf, and breed groups were included as main effects. Regression analyses were used to account for the effects of date of birth of calf. Chi-square analyses were used for tests of significance of differences in reproductive performance. Tests of significance among individual least-squares

CROSSBREEDING

BEEF CATTLE

7

means were made with Kramer's (23) modification of Duncan's range test. Separate analyses were made by periods for birth weight, average daily gain from birth to weaning, 250-day weight, and 250day weight per day of age (appendix tables 3 through 8). The analyses for carcass traits are given in Appendix Table 9. The mathematical models used in the analyses are shown on page 26. RESULTS AND DISCUSSION Period I The 6-year reproductive performance of Hereford and Brahman x Hereford cows when mated to Angus bulls is summarized in Table 1. Percentages of calves weaned per cow bred were 84.1 for the Brahman x Hereford cows and 80.4 for the Hereford cows. Although this difference is not significant, it is in agreement with reports of Turner et al. (34) and Cartwright et al. (5). Least-squares means for birth weights, 250-day average daily gains, and 250-day weights are reported in Table 2. Calves produced from Brahman x Hereford dams were slightly, but not significantly, heavier at birth than calves from Hereford dams. These differences are similar to those reported by Rhoad and Black (29), Kidder and Chapman (20), and Godbey et al. (14).
TABLE

1.

REPRODUCTIVE PERFORMANCE OF COWS', PERIOD

I
Weaned Pct.
83.3 66.7 89.4

Year

Cows No.
9 19
-24

Hereford

Calved Weaned Pct.
100.0 77.8 79.0

Brahman-Hereford

Cows No.
12 12 19

Calved Pct.
83.3 66.7 89.4

Pct.
100.0 77.8 79.0

1950 1951 _9 1952_...............

1953
1954_................ 1955 AVERAGE
1

88.3
76.9 85.0 82.2

83.3
73.1 80.0 80.4

27
35 33

81.5
91.4 87.9 85.5

81.5
91.4 81.8 84.1

26 20

All cows were bred to Angus bulls.
TABLE 2. LEAST-SQUARES MEANS1 OF PRE-WEANING TRAITS, PERIOD

I

Breeding of calf

Number

weight

Birth
Lb. 58.8 61.5

250-day 250-day 250-day 250-dayt bred weight WDA ADG Lb. 1.61b 1.81a Lb. 1.84b 2.05a Lb. 461b 518a Lb. 371b 481a

A x H Ax (B x H)
SMeans

72 107

followed by different letters differ at P<0.01.

8

ALABAMA

AGRICULTURAL

EXPERIMENT STATION

Calves from Brahman x Hereford dams had average daily gain of 1.81 pounds from birth to weaning, as compared with 1.61 pounds for calves from Hereford dams. Weaning weights were 513 and 461 pounds for the two breeding groups, respectively. These differences of 0.20 pound and 52 pounds are highly significant (P<0.01). They are in general agreement with previous reports of Lush et al. (24), Peacock et al. (26,27), Turner and McDonald (35), Warwick (37), and others who have shown that part-Brahman dams produce heavier calves at weaning than do straightbred British cows. The difference of 69 pounds of calf weaned per cow bred was highly significant (P<0.01). Total number of calves included in pre-weaning performance (Table 2) is not in agreement with number of calves included in reproductive performance (Table 3). This is because calves born after January 1 were not included in pre-weaning data. Period II This 4-year period was analyzed separately since the Shorthorn x Hereford cows were added to the study in 1952. Thus, for comparative purposes, calves produced by the Hereford and Brahman x Hereford dams during the 1952 season and through the 1955 season were included in both Period I and Period II. All calves were sired by Angus bulls. Table 3 gives reproductive performance of the different breeds of cows during Period II. Per cent calves born was 87.7, 83.6, and 80.9, respectively, for Brahman x Hereford, Shorthorn x Hereford, and Hereford cows. These differences were not significant. Differences in per cent calves born and per cent calves weaned were 2.2, 1.7, and 1.6 for the Hereford, Brahman x Hereford, and
TABLE 8. REPRODUCTIVE PERFORMANCE OF Cows , PERIOD II
1

Year

Cows No. 19 24 26 20

Shorthorn-Hereford Hereford Brahman-Hereford Calved Weaned Cows Calved Weaned Cows Calved Weaned Pct. 89.4 81.5 91.4 87.9 87.7 Pct. 89.4 81.5 91.4 81.8 86.0 No. 7 15 20 19 Pct. 71.4 66.7 90.0 94.8 83.6 Pct. 71.4 66.7 85.0 94.8 82.0

1952 1958__.. 1954 _.... 1955_.... AVERAGE 1 All cows

No. Pct. Pct. 79.0 79.0 19 88.3 83.3 27 76.9 73.1 35 33 85.0 80.0 78.7 80.9 were bred to Angus bulls.

CROSSBREEDING BEEF CATTLE
TABLE 4. LEAST-SQUARES MEANS' OF PRE-WEANING TRAITS, PERIOD

9

11
bred

Breeding of calf

Number weight Birth

250-day 250-day 250-day ADG WDA weight

Lb.
A x H A x (S x H)-.............. A x (B x H)
1

Lb.
1.68c 1.76b 1.84a

Lb.
1.92c 2.01b 2.09a

Lb.
481c 503b 523a

Lb.
379c 412b 450a

62 46 96

60.7 64.5 62.5

Means followed by different letters differ at P<0.05.

Shorthorn x Hereford dams, respectively. These differences are in agreement with Temple and Miller (33), Cartwright et al. (5), Riggs et al. (30), and Turner et al. (34). Least-squares means for pre-weaning traits are summarized in Table 4. Birth weights of calves from both groups of crossbred dams were slightly heavier than those from Hereford dams. These non-significant differences were 3.8 and 1.8 pounds, respectively, for calves from Shorthorn x Hereford and Brahman x Hereford. This is consistent with reports of Kidder and Chapman (20), McCormick and Southwell (25), and Godbey et al. (14). It also agrees with Turner and McDonald (35) that three-breed cross calves are approximately 3 pounds heavier at birth than two-breed cross
calves.

The average daily gain from birth to weaning of 1.84 pounds and 250-day weight of 523 pounds for calves from the Brahman x Hereford dams were significantly higher (P<0.05) than the average of 1.76 pounds and 503 pounds for calves produced by the Shorthorn x Hereford dams. Differences in average daily gain and 250-day weights were highly significant (P<0.01) between the calves from Brahman x Hereford dams and those from straightbred Hereford cows - 1.84 and 523 pounds and 1.68 and 481 pounds, respectively. These results are similar to those reported by Peacock et al. (26,27) and by Damon et al. (8). The differences between calves from Shorthorn x Hereford dams and calves from straightbred Herefords were significant (P<0.05) for average daily gain and 250-day weight. The differences in 250-day weights become even greater when they are compared as calf weight per cow in the herd at breeding. Period III This period includes 4 years (1956-59) in which Hereford bulls were mated to the same cows used in periods I and II.

10
TABLE 5.

ALABAMA AGRICULTURAL EXPERIMENT
REPRODUCTIVE PERFORMANCE
1

STATION

OF Cows, PERIOD

III

Year

Hereford

Brahman-Hereford

Shorthorn-Hereford

Cows Calved Weaned Cows Calved Weaned Cows Calved Weaned No. Pct. Pct. No. Pct. Pct. No. Pct. Pct.
64.7 84.6 61.5 100.0 79.5b 58.8 76.9 61.5 81.5 68.5b 32 31 26 22 75.0 77.4 88.5 100.0 83.8b 75.0 77.4 84.6 86.4 80.2a 19 17 16 16 89.5 79.0 88.2 82.4 100.0 100.0 87.5 81.3 91.2a 85.3a

1956___________ 17 1957__________ 13 1958 .........- 13 1959________ 11 AVERAGE
1

2 All

Means followed by different letters differ at P<0.05. cows were bred to Hereford bulls.

Per cent calves born and weaned were 91.2 and 85.3, 83.8 and 80.2, and 79.5 and 68.5, respectively, for Shorthorn x Hereford, Brahman x Hereford, and straightbred Hereford cows, Table 5. The Shorthorn-Hereford cows dropped a significantly higher percentage of calves than the other groups and all groups of crossbred cows weaned a significantly (P<0.05) larger percentage of calves than did straightbred cows. These results agree with those of Cartwright et al. (5) and Gaines et al. (11). Least-squares means for birth weight, average daily gain, and 250-day weight are presented in Table 6. There was no significant difference in birth weights of calves from straightbred Hereford dams and those from Shorthorn x Hereford dams. However, both groups were significantly (P<0.05) heavier at birth than calves from Brahman x Hereford dams. These results are in agreement with Cartwright et al. (5) and Ellis et al. (10), but differ from reports by Lush et al. (24) and Godbey et al. (14) that calves from Brahman x Hereford dams were heavier at birth. No significant differences were found among the three breeding groups in average daily gains and 250-day weights. The daily gains and 250-day weights of the calves from the Shorthorn x Hereford and Brahman x Hereford dams were approximately the same for Period III as for those reported for Period II,
TABLE 6. LEAST-SQUARES MEANS' OF PRE-WEANING TRAITS, PERIOD

III

of calf BreedingBreeding of

Num Number

Birth weight Lb.

250-day ADG Lb. 1.76 1.81 1.78

250-day 250-day wt./cow WDA weight bred Lb. 2.03 2.07 2.06 Lb. 508 518 515 Lb. 348c 415b 489a

H x H H x (B x H) H x (S x H)

37 89 58

67.4a 68.7b 67.7a

Means followed by different letters differ at P<0.05.

CROSSBREEDING

BEEF

CATTLE

1I

Table 6. However, average daily gain and 250-day weight of calves from Hereford dams were larger in Period III than in Period II. This may have been effected by the fact that 66 per cent of the Hereford cows were culled during periods I to III, as compared with only 20 per cent of the Shorthorn x Hereford and 39 per cent of the Brahman x Hereford cows. The differences become significant (P<0.05), however, when the comparison is on the basis of calf per cow bred. The Shorthorn x Hereford dams produced more pounds of calf per cow than the Brahman x Hereford dams. Both of these groups produced more pounds of calf than the Hereford cows. Period IV The percentage of calves born and weaned per cow bred was significantly larger (P<0.05) for the Brahman x Hereford cows than for the other two groups, Table 7. Calving percentages were 95.7 for Brahman x Hereford cows and 86.7 for the Hereford cows when both were mated to Hereford bulls. The Hereford cows mated to Angus bulls had a calving percentage of 78.8. Little difference was found among the groups in calf survival from birth to weaning. At least some of the poor performance of Hereford cows mated to Angus bulls can be explained by the use of a partially sterile bull during the 1960 season. Gaines et al. (11), Turner et al. (34), and Rollins et al. (31) report that Hereford cows mated to Angus bulls produce a larger percentage of calves born and weaned than do Hereford cows mated to Hereford bulls. However, Wiltbank et al. (38) found no difference in percentage of calves weaned from Hereford cows mated to Hereford bulls as from Hereford cows mated to Angus bulls.
TABLE

7.

REPRODUCTIVE PERFORMANCE

1

BY BREEDING GROUPS, PERIOD IV

Year

Hereford x BrahmanAngus x Hereford Hereford x Hereford Hereford Cows Calved Weaned Cows Calved Weaned Cows Calved Weaned No. 22 22 20 14 12 Pct. 95.5 95.5 85.0 78.6 66.7 86.7b Pct. 90.9 90.9 80.0 78.6 58.3 82.2b No. 17 16 18 21 13 Pct. 100.0 87.5 72.2 71.4 61.5 78.8e Pct. 94.1 87.5 72.2 61.9 53.9 74.1c No. 15 18 22 20 18 Pct. Pct. 100.0 100.0 88.9 88.9 90.9 86.4 100.0 90.0 94.4 83.3 95.7a 90.3a

1956_.... 1957_.... 1958_.... 1959_.... 1960_.... AVERAGE
1

Means followed by different letters differ at P<0.05.

12
TABLE 8.

ALABAMA AGRICULTURAL EXPERIMENT
LEAST-SQUARES MEANS
1

STATION
IV

OF PRE-WEANING

TRAITS,

PERIOD

Breeding of calf

Nuber Number

Birth weight Lb. 67.6a 65.7ab 64.5b

250-day 250-day 250-day 250-day ADG WDA weight bred Lb. 1.72b 1.72b 1.80a Lb. 1.99b 1.98b 2.05a Lb. 497b 495b 518a Lb. 409b 367c 463a

ng score

H x H___________ A x H.___________ H x (B x H)______
1 Means followed
2

74 63 84

10.2a 9.1b 9.4b

Grade code: 9 = low Good; 10 = average Good; 11 = high Good, etc.

by different letters differ at P<0.05.

Pre-weaning performances, birth weights, average daily gains from birth to weaning, and 250-day weights are given in Table 8. Straightbred Hereford calves were significantly (P<0.05) heavier at birth than calves out of Brahman x Hereford dams. There were no significant differences in birth weight among the other groups. These results agree with Cartwright et al. (5) and Ellis et al. (10). Calves from Brahman x Hereford dams gained faster and were heavier at 250 days of age (P<0.05) than were calves from the Hereford dams. Although straightbred Hereford and Angus x Hereford calves did not differ significantly for 250-day weight, the difference in 250-day calf weights per cow was significant

(P<0.05).
PERIOD V Angus x Hereford cows gave birth to a larger percentage (P<0.05) of calves than any other breed group, Table 9. Most of this difference resulted from a greater survival rate of calves sired by Hereford bulls. No significant differences existed among the other groups. Least-squares means of calf performance from birth to 250 days of age are presented in Table 10. No significant differences were found among birth weights of the various groups of calves. Calves produced by the Angus x Hereford dams, regardless of breed of sire, were significantly (P<0.01) heavier at 250 days of age than straightbred Hereford calves. This agrees with reports of Gaines et al. (11) and Turner and McDonald (35). Calves from the Hereford x (Brahman x Hereford) dams were significantly heavier (P<0.01) at 250 days of age than the straightbred Hereford calves but significantly lighter (P<0.01) than calves from

A

0
w

m m

z
TABLE 9. REPRODUCTIVE PERFORMANCE
1

BY BREEDING GROUPS, PERIOD

V
Angus x Angus-Hereford Cows Calved Weaned No. 0 5 9 13
14

m

Year

Hereford x Hereford Hereford x Angus-Hereford Hereford x Hereford (Brahman-Hereford) Cows Calved Weaned Cows Calved Weaned Cows Calved Weaned
Cows CavdWaem

r

No. 1959____________ 3 9 1960____________ 16 1961____________ 1962_______________28
1963__---------21

Pct. 100.0 100.0 75.0 78.3
85.7

Pct. 100.0 100.0 75.0 73.9
83.7

No. 6 7 8 12
13

Pct. 100.0 85.7 100.0 83.3
100.0

Pet. 100.0 85.7 100.0 83.3
100.0

No. 4 8 18 23
29

Pct. 100.0 100.0 84.3 70.0
100.0

Pct. 100.0 100.0 77.8 70.0
100.0

Pet. 00.0 100.0 88.9 84.6
92.9

Pet. 00.0 100.0 88.9 76.9
85.7

1964____________ 1965____________ 1966____________
AVERAGE

20 16 17

'Means

90.0 93.8 94.1 87.2b

90.0 93.8 88.2 86.4b

11 14 16

100.0 100.0 93.8 95.4a

100.0 100.0 9J3.8 95.4a

27 26 24

88.9 100.0 79.2 88.7b

85.2 92.3 79.2 86.2b

15 13 9

100.0 100.0 88.9 92.3a

100.0 100.0 77.8 85.9b

followed by different letters differ at P<0.05.

w

0

.

2

4
These cows and a v .Junction, calves

,

!r~a

and breed crosses evoluc xpermment at the Block Alobamo: 1. owand ?8 Hereford-' s ford cow and calf; 3. 1 1 ind 34 Angus- a Herefa 2 Hereford cow andV Hereford calf; 5. 1,2 An IiAngus-' 4 Hereford cu calf; 7. 1,2 Angus-'- 2 e ford- 1 Angus calf; and ford cow and 3'4 Herefoi raphs were made in spi

-3.

a-

.

.. I

0

v~j
ted in the crossbreeding Belt Substation. Marion '4 Hereford-'4~ Brahman Brahman calf; 2. HereAngus-' 2 Hereford cow rd calf; 4. 12 BrahmanzAngus-' 4 Brahman-' i Sus-I 2 Hereford cow and lf; 6. Hereford cow and !refo0rd cow and 34 Here8. 1 2 Angus-1 2 Hered-' 4 Angus calf. Phsotoing 1966.'"'

Iwo

16
TABLE 10.

ALABAMA

AGRICULTURAL

EXPERIMENT

STATION

LEAST-SQUARES

MEANS

1

OF PRE-WEANING

TRAITS,

PERIOD

V

Breeding of calf

Number

Birth weight

250-day 250-day 250-day 250-day Weaning 2 WDA weight w5d w score ADG

Lb. Lb. Lb. Lb. Lb. HxH 108 66.2 1.55c 1.82c 454c 392c 9.3b A x (A x H)-.... 67 64.2 1.78a 1.99a 497a 427b 10.4a H x (Ax H)_... 83 64.6 1.76a 2.02a 505a 482a 10.Sa H x H (B x H)__ 188 65.5 1.65b 1.91b 477b 411b 9.5b -1 Means followed by different letters differ at P<0.01. 2 Grade code: 9 = low Good; 10average Good; 11 = high Good, etc.

the Angus x Hereford dams. Differences between 250-day weights of calves from Angus x Hereford dams and sired by Hereford bulls and the other groups become greater when comparisons are made of calf weights per cow bred. Although differences were only one-third of a grade, calves from Angus x Hereford dams had significantly higher (P<0.01) weaning grades than calves from Hereford or Hereford x (Brahman x Hereford) dams. These findings are in agreement with those reported by McCormick and Southwell (25), Damon et al. (8), Rollins et al. (31), and Turner et al. (35). The least-squares means for post-weaning performance of steers, Table 11, show no significant differences among group means for total gain or average daily gain during the pasture period. A preliminary analysis indicated no significant differences among group means for age of calf at start of pasture period or number of days in the pasture period, Appendix Table 10. However, the feeding program during this period was designed for moderate growth, and absence of a high level of nutrition may have prevented the expression of full growth potential. During the feedlot period, steers from Hereford and those from
TABLE 11. LEAST-SQUARES MEANS' OF STEER POST-WEANING TRAITS, PERIOD V

Bredig oca H x H_....... Ax (Ax H) _..H x (Ax H)_... H x H (B x H)_
1
2

Number

Pasture period Initial Final ADG weight weight Lb. 498 535 561 520 Lb. 686 669 684 671 Lb. 1.46 1.33 1.85 1.50

Feedlot period Final ADG Final weight WDA Lb. 980 1003 1024 992 Lb. 2.40a 2.33ab 2.37a 2.25b Lb. 1.96b 1.97b 2.07a 1.97b

47 19 30 60

Means followed by different letters differ at P<0.05.
Unadjusted weaning weight.

CROSSBREEDING

BEEF

CATTLE

17

Angus x Hereford dams mated to Hereford bulls gained significantly (P<0.05) faster than steers from Hereford x (Brahman x Hereford) dams. No significant differences were found between average daily gain of Angus sired steers from Angus x Hereford dams and those from Hereford x (Brahman x Hereford) dams. Even though no significant differences were found among final feedlot weights, the Hereford sired steers from Angus x Hereford dams had a significantly (P<0.05) higher weight per day of age than any other group of steers. At time of slaughter, steers from Angus x Hereford dams by Hereford bulls were not only the heaviest but also the youngest, Appendix Table 9. These results show that the greatest differences in growth rate among the groups occurred during the pre-weaning period and this resulted in the differences in final feedlot weights. The differences in post-weaning gains indicate a compensatory gain for the straightbred Hereford calves. They gained slower from birth to weaning and made the most total gain from weaning to slaughter. These findings are in general agreement with Kincaid (21) who showed that crossbreds were 4 per cent heavier than straightbreds at 15 months of age and with Gregory et al. (18) that heterosis for feedlot gain was low. Dressing percentage for the 7/8 Hereford-1/8 Brahman steers was significantly higher (P<0.05) than for any other group, Table 12. Both groups of steers from Angus x Hereford dams had significantly higher (P<0.05) dressing percentages and chilled carcass weights than those from the straightbred Herefords. No significant difference was found in dressing percentage between the two groups from Angus x Hereford dams. Dressing

TABLE 12.

LEAST-SQUARES

MEANS'

OF STEER CARCASS CHARACTERISTICS,

PERIOD V

Breeding of calf

Chilled carcass weight Lb.

Dressing Carcass percent- WDA age Pct. Lb.

Rib fat Lb.

Ribeye area Sq. in.

Quality 2 grade

Tenderness, score

H x H-.........

553c

56.4c
57.5b 57.2b 58.2a

1.18
1.12 1.16 1.13

0.45b
0.58a 0.55a 0.48b

10.78
10.88 10.88 11.00

11.1b
12.7a 11.5b 10.6c

18.59b
17.50a 17.84a 19.81c

Ax (Ax H)-.... 577b H x (Ax H)_-. -586a H x H (B x H)__ 577b

SMeans followed by different letters differ at P<0.05. 2 Grade code: 10 = average Good; 11 = high Good; 12 = low Choice, etc. ' Tenderness determined by Warner-Bratzler shear (lower scores =
erness).

more tend-

18

ALABAMA

AGRICULTURAL

EXPERIMENT

STATION

percentage and carcass weight were lowest (P<0.05) for straightbred Herefords. Carcasses of steers from Angus x Hereford dams had significantly more rib fat (P<0.01) than carcasses of steers from the other groups of cows. These results agree with those of Damon et al. (9), Carpenter et al. (6), and Gregory et al. (18). The average quality carcass grades were 12.7, 11.5, 11.1, and 10.6 for the 3/4 Angus-1/4 Hereford, 3/4 Hereford-/4 Angus, straight Hereford, and %7 Hereford-1/8 Brahman, respectively. Only the Hereford and the 3/4 Hereford-1/ Angus carcasses did not differ significantly. These differences in quality grades are similar to those reported by Damon et al. (9), Gregory et al. (17, 18), and Vogt et al. (36), but greater than reported by Phillips et al. (28), Gerlaugh et al. (13), Godbey et al. (14), and Gaines et al. (12). Carcasses from steers with Angus breeding were most tender. They differed significantly (P<0.05) from the straightbred Herefords and at the P<0.01 level from the 7/8 Hereford-/ Brahman carcasses. No significant differences were found for carcass weight per day of age or ribeye area among the various breed groups of steers. SUMMARY From 1950 to 1966, crossbreeding studies involving Angus, Brahman, Hereford, and Shorthorn were conducted at the Black Belt Substation. The following results were obtained: (1) Crossbred cows producing three-breed calves dropped and weaned a higher percentage of calves than straightbred cows producing two-breed calves. (2) Crossbred cows producing backcross calves dropped and weaned a higher percentage of calves than straightbred cows producing either straightbred or two-breed calves. (3) Straightbred Hereford calves were as heavy or heavier at birth than other calves. (4) Three-breed calves were heavier at birth than were twobreed calves. (5) Backcross calves were heavier at 250 days of age than were either the two-breed or straightbred Hereford calves.

CROSSBREEDING

BEEF CATTLE

19

(6) Three-breed calves were heavier at 250 days of age than two-breed calves. (7) Differences in slaughter grade at weaning were small (one-third of a grade). (8) Differences in post-weaning rate of gain were small. However, straightbred Hereford calves gained significantly faster than part-Brahman calves. (9) The 3/4 Hereford- 1 4 Angus steers had a significantly higher final weight per day of age than the other groups. (10) Backcross calves produced heavier carcasses than straightbred Herefords. (11) Carcasses from steers with Angus breeding had more rib fat, graded higher, and were more tender than those from the other breed groups.

20

ALABAMA

AGRICULTURAL

EXPERIMENT

STATION

LITERATURE CITED

(1) BAKER,

A. L. AND W. H. BLACK. 1950. Crossbred Types of Beef Cattle for the Gulf Coast Region. USDA Cir. 844.

(2) BLACK, W. H., A. T. SEMPLE, AND J. L. LusH. 1934. Beef Production and Quality as Influenced by Crossing Brahman with Hereford and Shorthorn Cattle. USDA Tech. Bull. 417. (3) BUTLER, O. D., B. L. WARWICK, AND T. C. CARTWRICHT. 1956. Slaughter and Carcass Characteristics of Shortfed Yearling Hereford and Brahman x Hereford Steers. J. Ani. Sci. 15:93. (4) CARROLL, F. D., W. C. ROLLINS, AND N. R. ITTNER. 1955. Brahman x Hereford Crossbreds-Gains, Carcass Yields and Carcass Differences. J. Ani. Sci. 14:218. (5) CARTWRIGHT, T. C., G. F. ELLIS, JR., W. E. KRUSE, AND E. K. CROUCH. 1964. Hybrid Vigor in Brahman-Hereford Crosses. Tex. Agr. Exp. Sta. Tech. Mono. No. 1. (6)
CARPENTER,

J.

W., A. Z. PALMER, W.

G.

KIRK, F.

M.

PEACOCK,

AND

M. KOGER. 1981. Slaughter and Carcass Characteristics of Brahman and Brahman-Shorthorn Crossbred Steers. J. Ani. Sci. 20:336.
(7)
CLYBURN, T.

M., W. C.

MCCORMICK,

R. L. SAFFLE, AND B. L.

SOUrH-

(8)
(9)

WELL. 1961. Effects of Breed and Cross on Growth Rate and Carcass Characteristics of Beef Steers. J. Ani. Sci. 20:392. (Abst.). DAMON, R. A., JR., S. E. McCRAINE, R. M. CROWN, AND C. M. SINGLETARY. 1959. Performance of Crossbred Beef Cattle in the Gulf Coast Region. J. Ani. Sci. 18:437.

-CRAINE.

---

, R. M. CROWN, C. B. SINGLETARY, AND S. E.

Mc-

1960. Carcass Characteristics of Purebred and Crossbred Beef Steers in the Gulf Coast Region. J. Ani. Sci. 19:820. (10) ELLIS, G. F., JR., T. C. CARTWRIGHT, AND W. E. KRUSE. 19E5. Heterosis for Birth Weight in Brahman-Hereford Crosses. J. Ani. Sci. 24:93. (11) GAINES, J. A., W. H. MCCLURE, D. W. VOGT, R. C. CARTER, AND C. M. KINCAID. 1966. Heterosis from Crosses Among British Breeds of Beef Cattle: Fertility and Calf Performance to Weaning. J. Ani. Sci. 25:5.

(12)
(13)

---R. C. CARTER.
GERLAUGH,

,

G. V.

RICHARDSON, W. H. McCLURE, D. W. VOGT, AND 1967. Heterosis from Crosses Among British Breeds of

Beef Cattle: Carcass Characteristics.
PAUL, L. E. KUNKLE,

J. Ani. Sci. 26:1217.
AND D. C. RIFE.

1951.

Cross-

breeding Beef Cattle. Ohio Agr. Exp. Sta. Res. Bull. 703.

(14) GODBEY, E. G., W. C.
(15) GODLEY, W.

GODLEY, L. V. STARKEY,

AND E. D. KYZER.

1959. Brahman x British and British x British Mating for the Production of Fat Calves. S. C. Agr. Exp. Sta. Bull. 468.
C., E. C. GODBEY, E. D. KYZER, AND R. F. WHEELER. 1960. Crossbred and Purebred Dams for Production of Slaughter Calves. J. Ani. Sci. 19:203.

CROSSBREEDING

BEEF

CATTLE

21
SUMPTION, W. W. Preweaning Traits

(16) GREGORY, K. E., L. A. SWIGER, R. M. KOCH, L. J.
ROWDER, AND

J.

E.

INGALLS.

1965.

Heterosis in

of Beef Cattle. J. Ani. Sci. 24:21. (17)
INGALLS, W.

W.

, ROWDER, AND

L.

J.

J.

SUMPTION, R. M. KocH,
1966.

j. E.
Ani.

A. ROTHLISBERGER.

Heterosis

Effects on Growth Rate and Feed Efficiency of Beef Steers.

J.

Sci. 25:299.
(18)
INGALLS, W. W. ROWDER, AND
,

J.

L. J. SUMPTION, R. M. KocH, J. E. A. ROTHLISBERGER. 1966B. Heterosis

Effects on Carcass Traits of Beef Steers.

J. Ani. Sci. 25:311.

(19) (20)

HARVEY, WALTER R.

1960.

Least Squares Analyses of Data with

Unequal Subclass Numbers. USDA, ARS. 20-8.
KIDDER, R. W. AND H. L. CHAPMAN.

1952. A Preliminary Report of Weight Performances of Crossbred and Purebred Cattle at the Everglades Experiment Station from 1943 to 1952. Proc. Assoc. of Sou.

Agr. Workers. 49:56.

(21)
(22)

KINCAID, C. M. 1962. Breed Crosses with Beef Cattle in the South. Texas Agr. Exp. Sta. Sou. Coop. Ser. Bull. 81. KOGER,

M., W. L.
1962.

REYNOLDS,

WARNICK. Sci. 21:14.

W. G. KIRK, F. M. PEACOCK, AND A. C. Reproductive Performance of Crossbred and j.
Ani.

Straightbred Cattle on Different Pasture Programs in Florida.

(23) KRAMER, C. Y. 1957. Extension of Multiple Range to Group Correlated Adjusted Means. Biom. 13:13.
(24) LUSH, J. L., J. M. JONES, W. H. DAMERON, AND O. L. CARPENTER.

1930. Normal Growth of Range Cattle. Tex. Agr. Exp. Sta. Bull. 409.

(25)

McCORMICK, W. C. AND B. L. SOUTHWELL.

1957. A Comparison of

Brahman Crossbred with British Crossbred Cattle.

J. Ani. Sci. 16:207.
1956. Factors Af-

(26)
(27)

PEACOCK, F. M., W. G. KIRK, AND MARVIN KOGER.

fecting Weaning Weight of Range Calves. Fla. Agr. Expt. Sta. Bull.
578.
,

E. M. HODGES, W. L.

REYNOLDS,

AND

M. KOCER. 1960. Genetic and Environmental Influences of Weaning Weight and Slaughter Grade of Brahman, Shorthorn and BrahmanShorthorn Crossbred Calves. Fla. Agr. Exp. Sta. Bull. 624. (28) PHILLIPS, R. W., W. W. BLACK, B. KNAPP, JR., AND R. T. CLARK. 1942. Crossbreeding for Beef Production. J. Ani. Sci. 1:23. (29) RHOAD, A. D. AND W. H. BLACK. 1943. Hybrid Beef Cattle for Subtropical Climates. USDA Cir. 673. (30)
RIGGS,

J.

K.,

J.

C. SMITH, E. C.

CHAGAS,

AND

R.

J.

COOPER.

1966.

Rotational Crossbreeding of Beef Cattle in the Gulf Coast Area of
Texas. Beef Cattle Research in Texas. Cons. Prog. Rpts. 2411.

(31)

ROLLINS, W. C., R. G. LOY, F. D. CARROLL, AND K. A. WAGNON. 1969. Heterotic Effects in Reproduction and Growth to Weaning in Crosses of the Angus, Hereford and Shorthorn Breeds. J. Ani. Sci. 28:431.

22

ALABAMA AGRICULTURAL EXPERIMENT
STEELE, ROBERT G. D.
TEMPLE, R. S. AND D.

STATION

(32) (33)

AND JAMES H.

TORRIE.

1960. Principles and

Procedures of Statistics. McGraw-Hill Book Co. New York.
D. MILLER. 1961. A Comparison of Calving Percentages and Pre-weaning Performance of Various Breeds of Beef Cattle in a Crossbreeding Program. J. Ani. Sci. 20:392. TURNER,

(34)
(35)
(36)

J. W., B. R. FARTHING, AND G. L. ROBERTSON. 1968. Heterosis in Reproductive Performance of Beef Cows. J. Ani. Sci. 27:336.

1969. Mating-Type ComAND R. P. McDONALD. parisons Among Crossbred Beef Cattle for Preweaning Traits. J. Ani. Sci. 29:389.
__
VOGT, D. W., J. A. GAINES, R. C. CARTER, W. H. MCCLURE, AND C. M. KINCAID. 1967. Heterosis from Crosses Among British Breeds

of Beef Cattle. Post-Weaning Performance to Slaughter. 26:443.

J. Ani. Sci.

(37)

WARWICK, E.

J. 1953. Crossbreeding with Brahman Cattle. Am.

Breeds 4 (11):6. (38) WILTBANK, J. N., K. E. GREGORY, J. A. ROTHLISBERGER, J. E. INGALLS, AND C. W. KASSON. 1967. Fertility in Beef Cows Bred to Produce Straightbred and Crossbred Calves. J. Ani. Sci. 26:1005.

CROSSBREEDING

BEEF

CATTLE

23

CROSSBREEDING

BEEF CATTLE

23

APPENDIX
APPENDIX TABLE 1. COMPOSITION OF RATION FED DURING POST-WEANING PERFORMANCE TEST Ingredient Content

Per cent Ground snapped corn -----------------------------------50.0 Ground johnsongrass hay -----------------------------------26.5 Cottonseed meal --------------------------------- --12.5 Molasses-- - - - - - - - - -- - - - - - - - - - -- - - - -Sa lt - - - - - - - - - - - -- - - - - - - - - - - - - - - - - - - - - - - - -1

10.0 .0

APPENDIX TABLE 2. LEAST-SQUARES CONSTANTS FOR AGE OF DAM AND REGRESSIONS ON DATE OF BIRTH FOR 250-DAY WEANING WEIGHTS

Age of dam, years 2 --------------------------------------3 4 -------5 ----------6----------------------------------------------------------------

Number
64

250-day weight -4.295
-28.367

124
128

140
--

145

-8.607 -0.556

0.106

7-------------------------

129

8 ---------------------------------9 ---------------------------------------10-----------------------------------11 ----------------12 and older------------------------

107 73 44
31

15.031 5.928 -0.881 11.231
10.830

41

-0.420
0.68312078

Regression on date of birth: neaear _ ---------------------Quadratic .---------------------------

Cubic--------------

---------

- -------.-

AVERAGE -----------------------------

0.00356768 0.00008460 492.67

APPENDIX TABLE 3.

MEAN SQUARES OF PRE-WEANING TRAITS, PERIOD I

Source of variation Year-------------------------Sex
--------------------------

d.f.
5
1
---- ------

Birth weight
188
39

250-day ADG

250-day weight

0.3344**
0.4004*

Breed-------------------

1

196

Year x sex--------------------Year x breed---------------------------------------Sex x breed Regression on date of birth :
Linear-----------------------

5 5 1
1

87 38 19

1.01800 0.031
0.029 0.020

2739 0*

23534"0
2017 1492

7089140 2634

Quadratic-------------------Error---- --------------------44 P<0.01.

Cubic

-------

-------------

1
1

811**
237 68
50344

1.737*
0.023
0.049

t27389** 2800
5888

157

0.034

2446

24

ALABAMA

AGRICULTURAL

EXPERIMENT

STATION

24
APPENDIX TABLE 4. Source of variation

ALABMA

AGRICULTURLEPRMN

TTO

MEAN SQUARES OF PRE-WEANING TRAITS, PERIOD II d.f.

weight 3 0.26644 1872900 Year ----Sex-------------------------1 8 Breed----------------------------------2 160 Year x sex------------------------------- 0.036 3 84 2701 Year x breed----------------------------6 25 0.037 2416 Sex x breed ------------------------------- 1385 2 178 0.015
-----------------------------

Birth weight 2240

250-day

ADG

250-day

0.52934203 0.451'40 3076600
2.219* 0.003
0.040

Regression on date of birth: 1 Linear---------------------------Quadratic------------------------------1 Cubic---- ------------------------------1 Error---------------------------------183 P<0.05. ** P<0.01.
*

1221

355**
601 * 64

165156 959
5424

0.034

2401

APPENDIX TABLE 5. MEAN SQUARES OF PRE-WEANING TRAITS, PERIOD III

Source of variation

d.f.

weight

Birth

250-day ADG

Year-----------------------------------3 156 ----1 4284** Sex------------------------------Breed----------------------------------2 312** Year x sex----------------3 77
Year x Sex x

0.2900* 0.7574
0.036 0.041
0.048 0.095

250-day weight 20634*
55822*

breed--------------breed ----------------

1099 3370
3066 5941

6 2

17 83

Regression on date of birth:
Linear-----------------1
1

8620"
79

Cubic------------------Error--------------------*P<0.05.

Quadratic----------_-----

0.82600
0.042

6605404
3681

1 163

215 64

0.174* 0.035

142554 2481

**

P<0.01.

APPENDIX TABLE 6. MEAN SQUARES OF PRE-WEANING TRAITS, PERIOD IV

Source of variation
Y e ar -- - - - - - - - - - - - - - - - - - - -

d.f. 4

Birth weight
775'**

250-day 250-day Weaning ADG weight score 1

1 Bre ed --- - - - - - - - - - - - - - - - - Year x sex- - - -

0.3164** 24843-44 1.060**0 80467**
0.123* 0.045 0.078 0.035 1.308** 0.21700 6158 2839 6009** 1672

(3) 38.7

Year x breedSex x breed-----Regression on date of birth: Linear- - - - - - - - - Quadratic-

2 4 8 2

141 111 195"0 55

(1) 5.2 (2) 14.3 (3) 7.4 (6) 6.5 (2) 0.3

1
* 1
--

103244
170
125

10148144
10594*

Cubic -- - - - - - - - - * **

1

E rro r -- - - - - - - - - - - - - - - - - --

196

60

1.00400
0.034

5709604 2297 (152) 2.4

P<0.05. P<0.01. 1 Weaning scores were not obtained the first year. Degrees of freedom are given
in parenthesis.

CROSSBREEDING

BEEF

CROSSBREEDING

BEF

CATTLE CATTLE

25

2

APPENDIX TABLE 7. MEAN SQUARES OF PEE-WEANING TRAITS, PERIOD V

Source of variation

d.f.

Year----------------------------------- 7

Sex------------------------------------Breed .--------------------

---

1

weight 178*

Birth

250-day 250-day Weaning ADG weight
score

0.23200 16272 4 58.644

383**
56

1.180** 84460**
0.632
0.048 3198

3

36734 *
2519 2204

10.7* 22.1
2.9

Year x sex-------------------_-_-----------

Year x breed----------------------------------Sex x breed .--------------------------------_ Regression on date of birth: Linear----------------------------------

7 20
3

38 28
80

0.043 0.023

1.5 0.3

Quadratic------------------------------

Cubic
Error-----------------------* P<0.05. 00 P<0.01.

- ---------------

--------

1 1 1 351

7 105 339* 68

0.75500 4838100 0.050 2141 0.003 8
0.031 2193

1.7

APPENDIX TABLE 8. MEAN SQUARES FOR STEER PERFORMANCE ON PASTURE, PERIOD V

Souce f aritin
Souce f aritin
Year----------------------

df.
df.
6

Initial
age

Days in
period

AD
AD
1.107

111100
122

350804
378

Breed _---------------------

3

0.168

Year x breed-------------Error--------------------00 P<0.01.

17 129

143 140

706 484

0.111 0.117

APPENDIX TABLE 9. MEAN SQUARES OF STEER CARCASS CHARACTERISTICS, PERIOD V Source of variation

d.f.
3

Carcass weight

Carcass

WDA 0.004 0.004

Rib fat 0.025
0.1101

Ribeye
area

Quality

Tenderness
score' (4)11.10
.(3)3967*

grade

Year

Breed-

6 ___________________

-

3382** 0.024** 0.270 49 0.089** 165 2331** 0.009
307 353 0.91
24.74**4

93*
16.90*

Year x breed---Regression on Err

17
_

1.38
4.13

(11) 19.44
(1) 35.73

1 weight ----- 239783** 0.560**

128

0.019

0.85

0.87
Degrees

(11) 11.81
of freedom are

0* P<0.01. 1 Tenderness

*P<0.05.

scores obtained only during 1962-66.

given in parenthesis. APPENDIX TABLE 10.

LEAST-SQUARES MEANS FOE POST-WEANING PERFORMANCE, PERIOD V Pasture period Initial Days in Pasture gain period age Feedlot period Days in Feedlot Age at gain slaughter period

Breed group

Days 262 ___ H x H____________________
Ax(AxH)_
H x(A xH)----------H x H (B x

Lb.
95 101
91 99

Lb.
144 144
144 144

Days

266

138 134
123 151

344 334
340 321

501
511
495 506

H) ---------

260 263

26

ALABAMA AGRICULTURAL

EXPERIMENT STATION

Methods of Analysis The following linear model was used for each analysis:
Yijkl = Yi + Sj + Bk + YSij + YBik + SBk

+

where: Yi Sj Bk YS(ij) = = = =

+ b3BD 3 + Eijkl

b 1 BD

+

b 2 BD

2

p = the overall mean for the Yijkl when equal frequencies exist in
each of the subclasses. the effect of the i-th year. the effect of the j-th sex of calf. the effect of the k-th breed of calf. the effect of the interaction of the i-th year and the j-th sex of calf. the effect of the interaction of the i-th year and the k-th breed of calf. the effect of the interaction of the j-th sex of calf and the k-th breed of calf. linear regression of the dependent variable (Y) on the independent variable (BD), with all discrete variables held constant. quadratic regression of the dependent variable (Y) on the independent variable (BD), with all discrete variables held constant. cubic regression of the dependent variable (Y) on the independent variable (BD), with all discrete variables held constant. the date of birth of calf, day 1 on August 1 for each calving season.

YB (k) = SB(jk) = b1 = b2 = b3 = BD =

Eijkki= the random errors. Least-squares analyses for carcass characteristics of steers from Period V were made using the following linear model:
Yijk
=

p.

p

+ Y +

Bj +

YB(ij)

=

Yi = Bj = YB (ij) = b =
Elik =

the overall mean for the Yijk when equal frequencies exist in each of the subclasses. the effect of the i-th year. the effect of the j-th breed of calf. the effect of the interaction of the i-th year and the j-th breed of calf. linear regression of the dependent variable (Yi) on the carcass weight (xi).
the random errors.

+

b (xi-E)

+ Eijk

AGRICULTURAL EXPERIMENT STATION SYSTEM OF ALABAMA'S LAND-GRANT UNIVERSITY

With an agricultural research unit in every major soil area, Auburn University serves the needs of field crop, livestock, forestry, and horticultural producers in each region in Alabama. Every citizen of the State has a stake in this research program, since any advantage from new and more economical ways of producing and handling farm products directly benefits the consuming public.

0 0 /

©
©

r

®

21

Research

Unit Identification

Tennessee Valley Substation, Belle Mina. Sand Mountain Substation, Crossville. North Alabama Horticulture Substation, Cullman. Upper Coastal Plain Substation, Winfield. Forestry Unit, Fayette County. Thorsby Foundation Seed Stocks Farm, Thorsby. Chilton Area Horticulture Substation, Clanton. Forestry Unit, Coosa County. Piedmont Substation, Camp Hill. Plant Breeding Unit, Tallassee. Forestry Unit, Autauga County. Prattville Experiment Field, Prattville. Black Belt Substation, Marion Junction. Tuskegee Experiment Field, Tuskegee. Lower Coastal Plain Substation, Camden. Forestry Unit, Barbour County. Monroeville Experiment Field, Monroeville. Wiregrass Substation, Headland. Brewton Experiment Field, Brewton. Ornamental Horticulture Field Station, Spring Hill. Gulf Coast Substation, Fairhope.