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Group Title: Research report - North Florida Research and Education Center ; 88-10
Title: Beef production in relation to creep feeding, zeranol implants and breed type
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Title: Beef production in relation to creep feeding, zeranol implants and breed type I. Calf and cow perfromance
Series Title: Research report (North Florida Research and Education Center (Quincy, Fla.))
Physical Description: 24 leaves : ill. ; 28 cm.
Language: English
Creator: Prichard, D. L
North Florida Research and Education Center (Quincy, Fla.)
Publisher: North Florida Reseach and Education Center
Place of Publication: Gainesville Fla
Publication Date: 1988
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Subject: Beef cattle -- Feeding and feeds   ( lcsh )
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non-fiction   ( marcgt )
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Bibliography: Includes bibliographical references (p. 14-16).
Statement of Responsibility: by D. L. Prichard ... et al..
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BEEF PRODUCTION IN RELATION TO CREEP FEEDING,

ZERANOL IMPLANTS AND BREED TYPE: I. CALF AND COW PERFORMANCE

D. L. Prichard*, D. D. Hargrove, T. A. Olson and

T. T. Marshall

University of Florida,

Gainesville 32611































D. L. Prichard*, D. D. Hargrove, T. A. 01son and T. T. Marshall, North

Florida Research and Education Center, Route 3 Box 4370, Quincy, FL

32351. Contribution from the Animal Science Department, Inst. of Food

and Agric. Sci., Florida Stn., Univ. of Florida. Research Report 88-10.

*Corresponding author.











Abstract

A 2-yr study was conducted to evaluate the effects of creep feeding,

preweaning zeranol implants and breed type on calf and cow performance.

Two hundred calves sired by Brahman and Romana Red bulls and out of

Angus and Angus x Brown Swiss reciprocal crossbred (FI) dams were

stratified by breed type and sex to three creep treatments: no creep

feed (NC); long-term creep (LC), creep-fed from 56 to 210 d of age

(weaning); and short-term creep (SC), creep-fed from 146 to 210 d of

age. Alternate calves within sex, breed type and creep treatment were

implanted with 36 mg of zeranol at an average of 56 d and reimplanted 90

d later. The LC and SC calves had heavier (P<.001) 210-d weights than

NC calves (264 and 257 vs 231 kg, respectively) and the LC calves were

heavier (P<.001) at 146 d than NC calves. Frame score was not affected

(P>.20) by creep treatment. The LC calves had higher (P<.001) average

daily gains from 118 to 210 d of age and higher 146 and 210-d condition

scores than did NC calves. Cows with creep-fed calves gained more

weight during the breeding season than those with noncreep-fed calves.

Pregnancy rate was not affected (P>.46) by creep treatment of calf.

Zeranol implants increased (P<.01) 146 and 210-d weights (184 vs 175 kg

and 259 vs 243 kg) and average daily gains during all periods to

weaning. Cow weight gain, condition score, and pregnancy rate were not

affected (P>.14) by zeranol treatment of calf. Brahman-sired calves had

higher (P<.005) 146 and 210-d weights and frame scores than Romana

Red-sired calves. Calves out of Angus dams had lower (P<.001) 146 and

210-d weights, frame scores, and average daily gains from 56 to 146 and

to 210 days of age, but higher (P<.03) 210-d condition scores than

calves out of- F dams. The F cows gained more weight (P<.007) during











the breeding season, had a lower (P<.001) condition score and a higher

pregnancy rate (96.5 vs 86.8%) than the Angus cows. Cows with heifer

calves had a higher (P<.10) pregnancy rate than those with steer calves.

Spearman (rank-order) correlation coefficients between 146 and 210-d

weights of NC, SC and LC calves were .92, .92 and .94, respectively.

Rank-order correlation coefficients between 146 and 210-d weights of NC,

SC and LC calves out of Angus cows were .94, .90 and .88 respectively

and for Fl cows were .92, .91 and .93.

(Key Words: Creep, Zeranol, Brahman, Romana Red, Calf and Cow Perfor-

mance).

Introduction

Gross income in the cow-calf facet of the beef industry is highly

dependent on the production of heavyweight calves at weaning. Creep

feeding and implanting with growth stimulants are methods of increasing

preweaning gains (Cundiff et al., 1966; Scarth et al., 1968; Utley and

McCormick, 1976; Stricker et al., 1979; Corah, 1980; Lowman, 1980; Ochoa

et al., 1981). Advantages other than weight gain of calves have been

reported for creep feeding. These include increased weight, condition

and pregnancy rate of the dam (Jones and Jones, 1932; Stricker et al.,

1979). Creep feeding, however, has been implicated in the possible al-

tering of the maternal rank (weaning weight of calf) of cows within a

herd (Burns et al., 1966; Ochoa et al., 1981). Furthermore, it has been

suggested that creep feed is utilized best by calves suckling dams with

limited milk production (Christian et al., 1965). Little is known about

the combined effects of growth stimulants with creep feeding and varia-

tions in the dam's milk production on the preweaning performance of

calves.











The objective of this study was to evaluate the effects of and

interactions among creep feeding, zeranol implants and breed type on

calf and cow performance.

Materials and Methods

This project was conducted at the Beef Research Unit, Gainesville,

from April 1 through September 1, 1981 and 1982. The research unit is

located in north central Florida (latitude 290 40'N). Average maximum

and minimum temperatures for the 1981 and 1982 experimental periods

respectively were 32.8 and 19.3 C and 31.3 and 19.1 C. Monthly rainfall

averages during the experimental periods were 80.9 mm in 1981 and 170.3

mm in 1982. The major soil type is Leon fine sand, and varies from

moderately well drained to very poorly drained.

Two hundred calves, sired by Brahman and Romana Red bulls and out of

Angus and Angus x Brown Swiss F1 reciprocal crossbred dams were used in

this study. The Romana Red breed was developed in the Dominican

Republic from a base of native red criollo cows topcrossed to Mysore and

Nelore bulls and is about seven-eights Bos indicus breeding. Calves

were stratified by breed type and sex to the following creep treatments:

no creep feed (NC); long-term creep (LC), creep-fed from 56 to 210 d

(weaning); and short-term creep (SC), creep-fed from 146 to 210 d of

age. The creep feed contained 14% crude protein, not more than 8% crude

fiber, not less than 2.5% crude fat and 9000 U.S.P. units of vitamin A

per .45 kg. Creep feeders were located near shade and water. Alternate

calves within sex, breed type and creep treatment subgroups were

implanted with 36 mg of zeranol at an average age of 56 d and reim-

planted 90 d later.











A 60-d breeding season, from about April 1 to June 1, was used.

Calves were identified, weighed and bull calves castrated within 24 h of

birth. Calves were weaned at an average age of 210 d, and weaning

weights of all calves were adjusted to this age. Cows were palpated for

pregnancy at weaning time.

Cows and calves were maintained in pastures consisting primarily of

Pensacola bahiagrass (Paspalum notatum Flugge) and white clover

(Trifolium repens L.). Brood cows were wintered on corn silage plus

molasses and cottonseed meal to meet NRC requirements, from early

December until about March 15, when an adequate quantity of clover was

available in the pastures.

Cow-calf pairs within the LC and SC creep treatment groups were

stratified by breed, sex of calf and zeranol treatment to one of two

replicates (pastures). Cow-calf pairs in the NC groups were considered

one replicate and placed in a single pasture each year. The same four

pastures were used both years for the LC and SC creep groups; however,

the two pastures used for the LC creep treatment in 1981 were used for

the SC creep treatment in 1982. A different pasture was used for the NC

group each year. Stocking rates varied from 1.17 to 1.69 cow-calf pairs

per ha.

Data were analyzed by least squares, fixed model procedures using

the Statistical Analysis System (SAS, 1979). The model used for

analyses of calf traits included the fixed main effects of creep,

zeranol, breed of sire, breed of dam, sex, year and pasture nested

within creep treatment and year. Fixed main effects used in the model

for cow traits included creep, zeranol, breed of cow, breed of sire of

calf, .sex of calf, year and pasture nested within creep treatment and










year. Age of calf at the beginning of the trial was used as a covariate

(linear, quadratic) in final calf and cow models, except in the analyses

of 146 and 210 d weights. All cows in this study were 4 yr of age and

older, with the exception of six, which were 3 yr of age. Dam age

(linear, quadratic) was included in preliminary analyses; however, it

was removed from the calf model due to lack of significance. All two

and three-factor interactions were included in preliminary analyses.

Only significant interactions remained in the final models. Linear

contrasts of least-squares means for creep treatments were computed for

those calf and cow traits affected (P<.10) by creep treatment.

Response traits for the calf model were 146 and 210-d weights and

condition scores, preweaning average daily gain and frame score.

Spearman (rank-order) correlation coefficients were computed between 146

and 210-d weights of calves within creep treatment and within breed of

dam by creep treatment. Cow response traits included cow weight change

from the beginning (which was also the start of long-term creep feeding)

to the end of the breeding season, from the end of the breeding season

to July 1 (start of short-term creep feeding), and from July 1 to wean-

ing. Pregnancy rate and condition scores at the beginning and end of

the breeding season and at weaning were also analyzed. A scale of 1 to

17 was used for condition scoring of cows and calves (Andrade, 1980) and

frame scores were from 1 to 5 (Wakeman, 1978).

Results and Discussion

Calf Performance

Weights and Weight Gains. Least-squares means for calf preweaning

performance traits are shown in table 1. Mean 210-d weight was 252 kg.

Long-term (LC) and short-term (SC) creep-fed calves were 33 and 26 kg










heavier (P<.001), respectively, at 210 d than noncreep-fed calves (NC).

The LC calves were heavier (P<.001) at 146 d and had a higher (P<.001)

average daily gain from 56 to 146 d than SC and NC calves. The LC

calves were consuming an average of .7 kg of creep feed'd-1 at 118 d of

age and 1.15 kg'd-1 by 146 d of age (figure 1). There was no difference

(P>.50) among creep treatments for average daily gain from 56 to 118 d

of age, suggesting that producers who creep feed calves prior to 4 mo of

age are receiving little benefit in terms of increased weight gains.

The LC and SC calves had higher (P<.01) average daily gains from 146 to

210 d of age than NC calves. The SC calves gained faster (P<.08) from

146 to 210 d of age than LC calves. This may have been a compensatory

response, since the LC calves had higher average daily gains from 118 to

146 d of age. Similar advantages for creep feeding of calves from about

60 d of age to weaning were reported by Kuhlman et al. (1961), Stricker

et al. (1979) and Martin et al. (1981). Burns et al. (1966) reported a

14 kg advantage due to creep feeding calves 60 d prior to weaning at 215

d of age. The 14 kg advantage is about half as much as was obtained in

this study for an equivalent time period.

The LC calves gained 28 kg more weight from 56 to 210 d of age than

did the NC calves. The LC calves consumed an average of 187 kg of creep

feed during this time and required 6.7 kg of creep feed per kilogram of

gain above the NC calves. The SC calves gained 22 kg more.than the NC

calves and had a creep efficiency of 5.3 kg of feed per additional

kilogram of gain. Creep feed efficiency did not differ (P>.15) between

LC and SC calves.

Spearman correlation coefficients between 146 and 210-d weights of

calves by creep treatments are presented in table 2. The rank-order










correlation coefficient for LC calves was .94, compared to .92 for both

NC and SC calves. The mean change in rank between 146 and 210-d weights

of NC and LC calves was 5 vs 6 positions for SC calves. Maximum change

in rank varied from 37 for NC calves to 16 for LC calves. These data

indicate that creep feeding may not necessarily mask the milk producing

differences among cows, as theorized by previous researchers (Christian

et al., 1965; Burns et al., 1966; Ochoa et al., 1981).

Calves implanted with zeranol were 9 kg heavier (P<.001) at 146 d of

age and 16 kg heavier (P<.001) at 210 d than non-implanted calves (table

1). These findings are in agreement with Corah (1980), who reported an

increase in weight gain of about 10 and 24 kg, respectively, for one and

two implants preweaning. Zeranol implanted LC and SC calves gained .18

and .14 kg/d more (P<.001), respectively, from 146 to 210 d of age than

did the non-implanted calves on the same creep treatments, whereas im-

planted NC calves gained .06 kg more (P<.10) than non-implanted NC

calves. These data suggest an additional growth response from zeranol

with increased nutrition, a finding similar to that reported by Davis

(1980).

Calves produced by F1 dams were heavier (P<.001) than calves from

Angus dams at 146 and 210 d of age and had higher average daily gains

(P<.01) during all periods except from 146 to 210 d of age (table 1).

Breed of dam was confounded in this study with breed composition of

calf. All calves nursing F1 dams were 1/4 Brown Swiss, 1/4 Angus and

1/2 either Brahman or Romana Red breeding. Calves nursing Angus dams

were 1/2 Angus and 1/2 Brahman or Romana Red. Calves nursing reciprocal

crossbred Angus x Brown Swiss dams have been shown to grow more rapidly

than those nursing Angus dams (Gregory et al., 1978; Andrade, 1980;










Euclides et al., 1983). The additive response for growth rate obtained

from creep feed and milk consumption was partially confounded in this

study by the fact that calves with greater growth potential were nursing

dams with higher milk production. Euclides et al. (1983) showed that F1

dams produced about 1.5 kg/d more milk than Angus dams. These data do

not concur with the findings of Christian et al. (1965), Burns et al.

(1966) and Ochoa et al. (1981), who suggested that creep feeding tends

to mask the milk production differences among cows, and that calves

nursing poorer milking dams may compensate by eating more creep feed.

Wyatt et al. (1977) also stated that as milk intake of the calf

increases the non-milk inputs, forage and creep feed, are reduced.

There was no significant creep treatment by breed of dam interaction for

any calf trait. Rank-order correlations coefficients between 146 and

210-d weights were similar across both breeds of dam and creep

treatments (table 3).

The interaction of creep, zeranol and breed of dam affected (P<.03)

average daily gain from 146 to 210 d of age. The greatest response to

zeranol for average daily gain from 146 to 210 d of age was shown by SC

calves nursing Angus dams and by LC calves nursing Angus and F1 dams

(table 4). Zeranol implants increased (P<.03) the rate of gain from 146

to 210 d of age more in calves nursing Angus dams than in those nursing

F1 dams. Brahman-sired calves were heavier (P<.001) at 146 and 210 d of

age and had higher (P<.02) average daily gains from 56 to 210 d of age

than calves sired by Romana Red bulls.

Steer calves were heavier (P<.001) at 146 and 210 d of age and

gained faster in all periods (P<.001) than heifer calves (table 1). The

zeranol effect on 210-d weight was greater (P<.09) in steers than










in heifers. Implanted steers were 22 kg heavier at 210-d of age than

non-implanted steers, whereas the 210-d weight of implanted heifers was

11 kg heavier than that of non-implanted heifers. Davis (1980), on the

other hand, reported no significant zeranol treatment by sex of calf

interaction effect on calf weaning weight. Breed of dam by sex of calf

interaction affected 146-d (P<.05) and 210-d (P<.06) weights. Steer

calves nursing F1 dams were 25 and 33 kg heavier at 146 and 210 d of

age, respectively, than heifers nursing F1 dams. Comparable advantages

for steers nursing Angus dams over heifers nursing Angus dams were 14

and 20 kg.

Pasture, nested within creep treatment and year, affected (P<.003)

average daily gains from 56 to 118, 118 to 146, and 146 to 210 d of age.

Pastures were monitored each month for quality and quantity of available

forage. Available dry matter (kg) per cow-calf pair, mean pasture crude

protein percentage and mean pasture IVOMD percentage were used in depen-

dent analyses in an attempt to account for variability due to effect of

pasture. However, due to reduced R2 values and lack of agreement be-

tween actual means and least-square means, these covariables were

dropped from the final analyses in favor of the total effect of pasture.

Frame and Condition Scores. Least-squares means for frame and

condition scores are presented in table 1. Creep feeding did not affect

(P>.20) frame score at weaning. Stricker et al. (1979), on the other

hand, reported that creep feeding resulted in an increased frame size.

The LC calves were fatter (P<.001) at 146 d of age than calves not

receiving creep feed, and LC and SC calves were fatter (P<.001) than NC

calves at 210 d. There was no difference (P>.16) in condition score

between LC and SC calves at 210 d of age.










Zeranol implants did not affect (P>.23) frame score at weaning nor

condition score at 146 and 210 d of age. These results are in agreement

with those of Davis (1980) and Gerken et al. (1978). Corah (1980),

however, reported that calves implanted at birth with 36 mg of zeranol

and again at 4 mo of age had less condition at weaning than non-

implanted calves.

Calves produced by F1 dams were larger framed (P<.001) than those

out of Angus dams, but had lower condition scores at 210 d (P<.03). The

F1 dams had been shown to produce more milk (Euclides et al., 1983) and

were nursing calves with one-fourth Brown Swiss breeding. These calves

were larger framed and later maturing, thus, did not fatten as early as

the one-half Angus calves nursing Angus dams. Brahman-sired calves had

larger frames (P<.001) than those sired by Romana Red bulls.

Steer calves were larger framed (P<.001) and thinner at 146 (P<.08)

and 210 d (P<.001) than heifer calves. Breed of dam by sex of calf

interaction affected (P<.06) frame score. Steers and heifers nursing Fl

dams had larger frames (3.5 and 3.0, respectively) than those nursing

Angus dams (2.8 and 2.6).

Cow Performance

Least-squares means for cow weight change, condition score and

pregnancy rate are presented in table 5. Cow condition score at the

beginning of the breeding season did not differ (P>.57) among the three

calf creep-treatment groups. Cows with LC calves, however, gained more

(P<.09) weight during the 60-d breeding season and had a higher (P<.02)

average condition score at the end of the breeding season than those

nursing calves not receiving creep feed. Other authors have suggested

that increases in cow weight gain and condition due to creep feeding of










calves might result in a subsequent increase in pregnancy rate (Jones

and Jones, 1932; Stricker et al., 1979). In this study, however,

pregnancy rate was not affected (P>.46) by creep treatment of calf

(89.5% for the non-creep group vs 92.7% for the creep-fed group) even

though a difference did exist in cow weight change and condition score.

Creep treatment of the calf did not affect (P>.11) cow weight gain from

the end of the breeding season to July 1 but cows nursing SC and LC

calves gained more (P<.001) weight from July 1 until the calves were

weaned on September 1. Creep treatment of calf had no effect (P>.28) on

condition score of dam at weaning.

Weight gain, condition score and pregnancy rate of dam were not

affected by zeranol treatment of calves. In this study, zeranol

implanted calves gained more rapidly throughout the nursing period than

did non-implanted calves. Since zeranol implants in calves had no

affect on cow weight gain, condition score or pregnancy rate, the

increased weight gain of the calf apparently did not place an added

stress on the cow.

Angus cows gained less (P<.02) weight from the beginning of the

breeding season to July 1 but had higher (P<.001) condition scores than

did F1 cows. The Fl cows had a higher (P<.07) pregnancy rate than Angus

cows (96.6 vs 86.8%).

Cows nursing Brahman-sired calves gained more (P<.09) weight during

the breeding season than those nusring Romana Red-sired calves. There

was no difference, however, in weight gain of calves during the breeding

season due to breed of sire (table 1). Breed of sire of calf did not

affect (P>.19) cow condition score or pregnancy rate. Sex of calf did

not affect (P>.55) cow weight gain or condition score; however, cows










nursing heifer calves had a higher (P<.10) pregnancy rate than those

nursing steer calves.

It can be concluded that calves receive very little benefit from

creep feed prior to 120 d of age. Creep feeding calves from about 5 mo

of age until weaning at 7 mo results in more efficient utilization of

creep feed and almost as much increase in weight gain as creep feeding

from 2 mo of age. The effects of creep feed intake and milk intake on

preweaning weight gain were shown to be additive in calves with above

average growth potential. Increased levels of nutrition, from creep feed

and milk, should result in increased growth response to zeranol.

Pregnancy rate was not increased by creep feeding of calves when the

cows had adequate nutrition during the breeding season.










LITERATURE CITED

Andrade, V. J. 1980. Effect of nutritional level during late gestation

on the performance of two-year-old heifers. Ph.D. Dissertation Univ.

of Florida, Gainesville.

Burns, W. C., R. E. Deese and M. Koger. 1966. Creep feeding beef

calves in Florida: Effects on weight and market grade. USDA Prod.

Res. Rep. No. 88.

Christian, L. L., E. R. Hauser and A. B. Chapman. 1965. Association of

preweaning and postweaning traits with weaning weight in cattle. J.

Anim. Sci. 24:652.

Corah, L. R. 1980. The 1980's/ A new era in cattle management. Kansas

State Univ. Coop. Ext. Bull. L-557.

Cundiff, L. V., R. L. Willham and C. A. Pratt. 1966. Effects of

certain factors and their two-way interactions on weaning weight in

beef cattle. J. Anim. Sci. 25:972.

Davis, D. I. 1980. Growth response of nursing calves to zeranol

implants. Texas Agr. Ext. Svc. Pub. 394-3644. p. 65.

Euclides, K., Filho, J. Restle, T. A. Olson, M. Koger and D. D.

Hargrove. 1983. Measures of efficiency of calf production from cows

of different size and milking ability. Florida Beef Cattle Res.

Rep. Univ. of Florida, Gainesville. p. 13.

Gerken, H. J., Jr., A. L. Eller, Jr., J. P. Fontenot and W. D. Lamm.

1978. Growth promoting implants A tool for profit in beef

production. Virginia Polytechnic Institute and State Univ. Ext.

Division. Anim. Sci. Bull. 783.

Gregory, K. E., L. V. Cundiff, G. M. Smith, D. B. Laster and H. A.

Fitzhugh. 1978. Characterization of biological types of cattle -










Cycle II: 1. Birth and weaning traits. J. Anim. Sci. 47:1022.

Jones, J. M. and J. H. Jones. 1932. Creep feeding range calves. Texas

Agr. Exp. Sta. Bull. No. 470.

Kuhlman, L. R., R. D. Furr and A. B. Nelson. 1961. Creep-feeds and

creep-feeding fall calves until spring vs. weaning. J. Anim. Sci.

20:399 (Abstr.).

Lowman, B. 1980. The sequential implanting of beef cattle with Ralgro.

Ralgro Seminar, Ponteland, Newcastle upon Tyne. p. 1.

Martin, T. G., R. P. Lemenager, G. Srinivasan and R. Alenda. 1981.

Creep feed as a factor influencing performance of cows and calves.

J. Anim. Sci. 53:33.

Ochoa, P. G., W. L. Mangus, J. S. Brinks and A. H. Denham. 1981.

Effect of creep feeding bull calves on dam most probable producing

ability values. J. Anim. Sci. 53:567.

SAS. 1979. Statistical Analysis System User's Guide. SAS Institute

Inc., Cary, NC.

Scarth, R. D., R. C. Miller, P. J. Phillips, G. W. Sherritt and J. H.

Ziegler. 1968. Effects of creep feeding and sex on the rate and

composition of growth of crossbred calves. J. Anim. Sci. 27:596.

Stricker, J. A., A. G. Matches, G. B. Thompson, V. E. Jacobs, F. A.

Martz, H. N. Wheaton, H. D. Currence and G. F. Krause. 1979.

Cow-calf production on tall fescue-ladino clover pastures with and

without nitrogen fertilization or creep feeding: Spring calves. J.

Anim. Sci.. 48:13.










Utley, P. R. and W. C. McCormick. 1976. Performance and carcass char-

acteristics of steers, steers implanted with zearalanol and bull

calves. Georgia Agr. Exp. Sta. Res. Rep. Univ of Georgia, Athens.

p. 221.

Wakeman, D. L. 1978. A classification system for beef calves and

cattle. Proc. 27th Annu. Beef Cattle Short Course. Univ. of

Florida, Gainesville. p. 18.

Wyatt, R. D., M. B. Gould, J. V. Whiteman and R. Totusek. 1977. Effect

of milk level and biological type on calf growth and performance.

J. Anim. Sci. 45:1138.










Long-Term Creep
Short-Term Creep- -


/

I

I

I


168 182 196 210


DAYS
Average daily creep


OF AGE
feed intake.


1.25-


.75-


.25


Figure 1.











TABLE 1. LEAST SQUARES MEANS FOR CALF TRAITS.


Condition
Weight, kg Average daily gain, kg Frame score
Source of 146 210 56-146 56-118 118-146 146-210 56-210 score 146 210
variations n d d d d d d d 210 d d d


Creep treatment
Probability level
No creep
Short-term
Long-term

Zeranol treatment
Probability level
No zeranol
Zeranol

Breed of sire
Probability level
Brahman
Romana Red

Breed of dam
Probability level
Angus
F1


.001
174
177
187


.001
101 175
99 184


.001
111 185
89 173


.001
77 169
123 190


.001
231
257
264


.001
243
259


.001
258
244


.001
239
262


.001
1.00
1.02
1.10


.001
1.00
1.08


.01
1.06
1.01


.001
.97
1.11


.50
1.09
1.10
1.13


.001
1.06
1.15


.93
1.11
1.09


.001
1.03
1.17


.001
.81
.85
1.03


.03
.87
.94


.001
.96
.85


.01
.85
.96


.001
.90
1.25
1.20


.001
1.06
1.18


.13
1.13
1.11


.11
1.10
1.14


.001
.96
1.11
1.14


.001
1.02
1.12


.02
1.09
1.05


.001
1.03
1.12


.20
2.9
2.9
3.0


.46
2.9
3.0


.001
3.1
2.8


.001
2.7
3.2


.001
9.3
9.3
9.9


.41
9.4
9.6


.33
9.6
9.4


.88
9.5
9.5


.001
10.0
11.0
11.3


.23
10.7
10.9


.83
10.8
10.7


.03
10.9
10.6










Table 1. Continued.


Condition
Weight, kg Average daily gain, kg Frame score
Source of 146 210 56-146 56-118 118-146 146-210 56-210 score 146 210
variation n d d d d d d d 210 d d d

Sex of calf
Probability level .001 .001 .001 .001 .001 .001 .001 .001 .08 .001
Steer 82 189 264 1.10 1.15 .99 1.17 1.13 3.1 9.4 10.4
Heifer 118 170 238 .98 1.06 .82 1.07 1.02 2.8 9.6 11.1

Mean 200 180 252 1.04 1.11 .91 1.12 1.08 3.0 9.5 10.8
RSD 16 21 .12 .16 .28 .14 .11 .5 .9 1.0

ayear influenced (P<.05) 146 and 210-d weights, daily gains in all periods except 118-146 d of age and
146-d condition score. Pasture nested within creep and year affected (P<.004) average daily gains from
56-118 d, 118-146 d and 146-210 d of age. Creep x year interaction affected (P<.05) 146-d weight. The
creep x zeranol interaction affected (P<.08) average daily gains from 56-118 d and 146-210 d. The creep
x breed of dam x zeranol interaction affected (P<.08) average daily gain from 146-210 d of age and 146-d
condition score. The breed of dam x zeranol interaction affected (P<.03) average daily gain from 146-210
d of age. The breed of dam x sex of calf interaction affected (P<.06) 146 and 210-d weights and frame
score. The zeranol x sex of calf interaction affected (P<.09) 210-d weight and condition score and
average daily gains from 56-146 d and 146-210 d of age.
Residual standard deviation.




















TABLE 2. SPEARMAN CORRELATION COEFFICIENTS BETWEEN 146 AND
210-DAY WEIGHTS OF CALVES BY CREEP TREATMENT


Creep Meana Maximuma
Treatment Rs Change Change


NC .92 5 37
SC .92 6 27
LC .94 5 16

aExpressed as absolute values for changes in rank




















TABLE 3. SPEARMAN CORRELATION COEFFICIENTS BETWEEN 146 AND
210-DAY WEIGHTS OF CALVES BY CREEP TREATMENT AND BREED OF
DAM


Breed of Creep Treatment
dam NC SC LC


R .94 .90 .88
Angus Mean change 2 3 3
Maximum change 6 7 8

R a .92 .91 .93
Fl Mean change a 3 4 4
Maximum change 18 12 12

aExpressed as absolute values for changes in rank.




















TABLE 4. LEAST SQUARES MEANS FOR AVERAGE DAILY GAIN
FROM 146 TO 210 DAYS OF AGE BY CREEP TREATMENT, ZERANOL
TREATMENT AND BREED OF DAM


Angus F_
Creep treatment No No
zeranol Zeranol zeranol Zeranol

NC 0.83 0.91 0.90 0.94
SC 1.12 1.38 1.24 1.25
LC 1.07 1.26 1.15 1.33
Mean 1.02 1.19 1.10 1.17











TABLE 5. LEAST SQUARES MEANS FOR COW TRAITS


Weight change, kg Condition score
Source ofa Entire End of July 1 Beginning of End of breeding
variation breeding Breeding to to breeding season, Weaning, Pregnancyb
n season July 1 Weaning season, April 1 June 1 Sept. 1 %


Creep treatment
Probability level
No creep
Short-term
Long-term


.09
54.9
49.6
57.7


Zeranol treatment
Probability level .26
No zeranol 101 51.8
Zeranol 99 55.5

Breed of sire of calf
Probability level .09
Brahman 111 57.0
Romana Red 89 50.3

Breed of cow
Probability level .007
Angus 77 49.2
F1 123 58.2


.11
3.5
7.3
1.4


.94
5.6
4.0


.25
4.7
4.8


.02
2.5
7.0


.001
6.5
24.1
22.5


.82
17.4
17.7


.91
18.2
16.9


.89
17.0
18.1


.57
5.7
5.6
5.8


.45
5.8
5.6


.19
5.6
5.8


.001
6.1
5.3


.02
7.1
6.8
7.3


.14
7.2
7.0


.51
7.0
7.1


.001
7.7
6.4


.28
7.6
7.8
7.5


.43
7.7
7.5


.73
7.6
7.6


.001
8.6
6.7


.46
89.5

92.7


.60
92.5
90.9


.94
92.0
91.4


.07
86.8
96.6











Table 5. Continued.


Weight change, kg Condition score
Source ofa Entire End of July 1 Beginning of End of breeding b
variation breeding Breeding to to breeding season, Weaning, Pregnancy
n season July 1 Weaning season, April 1 June 1 September 1 %

Sex of calf
Probability level .75 .59 .61 .59 .55 .56 .10
Steer 82 53.8 5.8 18.1 5.7 7.0 7.7 88.6
Heifer 118 53.5 3.7 17.0 5.7 7.1 7.6 94.8

Mean 200 54.6 5.3 17.3 5.7 7.1 7.6 93.0
RSDc 19.6 14.9 13.9 .9 .9 1.1 24.7

year influenced (P<.002) all cow traits except pregnancy rate.
Pasture nested within creep and year affected (P<.002) weight change in all periods and condition scores
at the end of the breeding season (P<.10) and at weaning (P<.03), and also affected pregnancy rate
(P<.10).
The creep x year interaction affected (P<.001) weight change in all periods and condition score at weaning
(P>.005).
Breed of sire of calf x breed of cow interaction influenced (P<.04) condition score at weaning.
In the analysis of variance for pregnancy rate there were only two creep treatments.
Short-term creep-fed calves were considered as non-creep.
Residual standard deviation.




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