Beef Production of Brahman, Shorthorn, and Their Crosses on Different Pasture Programs ( Publisher's URL )

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Beef Production of Brahman, Shorthorn, and Their Crosses on Different Pasture Programs
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1.This document is Bulletin 780, one of a series of the Department of Animal Science, Florida Agricultural Experiment Station, Institute of Food and Agricultural Sciences, University of Florida. First Printed: February 1976. Sec ond Printing: November 1984. Revised May 1999. Please visit the EDIS Web site at 2.Peacock, F. M., Associate Animal Husbandman, ARC, Ona; Koger, M., Animal Geneticist, Universtiy of Florida, Gainesv ille; Kirk, W. G., Animal Scientist, Emeritus; Hodges, E. M., Agr onomist, ARC, Ona; Crockett, J. R., Associate Animal Geneticist, AREC, Belle Glade. Cooperative Extension Service, Ins titute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611. Florida Agricultural Experiment Station, Institute of Food and Agricultural Sciences, University of Florida, Richard L. Jones, Dean for Research, publishes this information to further programs and related activities, available to all persons regardless of race, color, age, sex, handicap or national origin. Information about alternate formats is available from Educational Media and Services, University of Florida, PO Box 110 810, Gainesville, FL 32611-0810. Bulletin 780Beef Production of Brahman, Shorthorn, and Their Cro sses on Different Pasture Programs1 F. M. Peacock, M. Ko g er, W. G. Kirk, E. M. Hod g es, and J. R. Crockett2Beef production is the result of a combination of both genetic and environmental factors. Genetic factors may be masked by induced or natural environmental influences which hinder expression of hereditary traits. Environmental influences either complement or limit the genetic potential of the animal. Thus, it is important to assess the productivity of various breed groups in alternative production systems in order to develop the most efficient production programs. Limited information is available on the comparative productive behavior of Brahman, European-origin, and crossbred cattle under variable environmental cond itions. The purpose of this study was to evaluate the performance of Brahman, Shorthorn and crossbred cattle involving those two breeds on three pasture-management programs in the semi-tropical environment of south central Florida.Materials and MethodsThe study was designed to evaluate the comparative production of Brahman, Shorthorn, and various crosses of these two breeds when maintained on native, or a combination of native, and all-improved pasture. The design of the trial is shown in Table 1.Breed GroupsThe herds on each of the forage programs included approximately 60 cows. Each herd included five breed groups as follows: ten Brahman (B), ten 3/4 Brahman-1/4 Shorthorn (BS), twenty Brahman-Shorthorn firstcrosses31(F1), ten 3/4 Shorthorn-1/4 Brahman (SB) and ten31Shorthorn (S). The trial was conducted in two 5-year phases. During the first phase the B, the BS, and one-half31of the F cows were mated to Brahman bulls while the1remaining groups were mated to Shorthorn bulls. This procedure resulted in a balanced design considering breed of calf but resulted in confounding of breed of bull with breed of cow since only one-half of the possible breed combinations were included during one phase. The procedure was dictated, however, by the availability of replacement females for the study and the decision to maintain 10 animals per breed group x year sub-cell rather than five, which would have resulted had breed of cow and breed of sire been used annually in all possible combinations. During the second phase, breed of sire for the different cow groups was reversed from that of the first phase. Thus, including both phases each breed of cow was mated to bulls of both breeds. By including two mating groups (30 F cows mated each to B and S bulls) across all1years it was possible to remove year effects and obtain a satisfactory comparison of all breed combinations.


Beef Production of Brahman, Shorthorn, and Their Crosses on Different Pasture Pro g rams Pa g e 2Ma y 1999 Table 1. Desi g n of Trial. Phase 1, 1957 to 1961Phase 2, 1962 to 1966 Pasture pro g ram Pasture pro g ram Breed of Breed of sire sire 123 123 Breed of cow Matin g s per y ear Matin g s per y ear Brahman ( B ) B101010 S101010 3/4 B 1/4 S ( B ) B101010 S10101031/2 B 1/2 S ( F ) B101010 S10101011/2 B 1/2 S ( F ) S101010 B10101011/4 B 3/4 S ( B ) S101010 B1010101Shorthorn ( S ) S101010 B101010(33.3% N) for pangolagra ss, or a like am ount of completePasture-Management ProgramsProgram 1 This program involved native grasses, mainly Aristida and Andropogon spp. (wiregrass and broomsedge). During the first 5-year period, the 60 cows and their calves grazed 812 acres of native range divided into five fields. Eighty acres of each of these five fields were burned on alternate years. A reduction to 772 acres in the program was made during the second phase. Supplemental feed was provided on native range only to the extent necessary to prevent extreme weight loss in the cows. Cows were supplemented during the winter months with 41% cottonseed pellets and a limited amount of hay in the first phase. In phase 2 an average of 555 pounds of hay, 52 pounds cottonseed meal (41%), and 52 pounds of citrus meal were fed over a period averaging 109 days annually beginning in D ecember. Program 2 This program included a combination of 73 acres of improved pasture plus 315 acres of native grasses for the 60-cow herd. The improved pasture included 40 acres of Pensacola bahiagrass ( Paspalum notatum Flugge.), 15 acres of Coastal bermudagrass ( Cynodon dactylon (L.) Pers.) and 18 acres of Pangola digitgrass ( Digitaria decumbens Stent.) during the first phase. For the second phase the bermudagrass was replaced by digitgrass. Approximately 20 acres of the bahiagrass was grown in conjunction with Hairy Indigo ( Indigofera hirsuta Linn.) with the remaining 20 acres being in combination with non-irrigated white clover ( Trifolium repens L.) and Hubam sweetclover ( Melilotus alba Desv.). The cattle had a ccess to the native grasses continuously and generally to one field of improved pasture. The cattle on all programs were bred in a restricted The annual fertilizer program per acre for improvedthe calves were weaned at one time in early September. grass pastures was approximately 400 p ounds of 8-8-8 (N-PO-KO) plus 150 p ounds of ammonium nitrate252fertilizer plus 100 p ounds of ammonium nitrate for bahiagrass pastures. The legume pastures received 250 pounds per acre of 0-8-24 fer tilizer a nnually with an extra application of muriate of potash averaging 32 pounds KO2per acre on the white clover. Cattle were given suplemental feed only in the winter of 1957-58 during phase 1. During the last 5-year period the cattle on Program 2 r eceived supplemental feed (43 pounds hay, 65 p ounds cottonseed meal and 31 pounds citrus meal per cow) for an average of 72 days annually from January to April. Program 3 This program included only improved pastures. During the first phase it included 76 acres of pangolagra ss, 20 acres of which were irrigated and over-planted with white clover. Due to pasture becoming less productive the area was increased to 107 acres for the second phase. This change resulted in 70 acres of all pangola digitgrass, 27 acres of digitgrass overplanted with white clover, and 10 acres of bahiagrass. Pasture fertilization in Program 3 followed the same pattern as described for Program 2. Cattle in Program 3 were maintained in a high nutritional status at all times. For the most part, the cattle maintained good weights from pasture, as only an average of 280 p ounds of hay per cow was fed for each of the five winters.General Managementseason of 105 days extending from March 15 to July 1. All


Beef Production of Brahman, Shorthorn, and Their Crosses on Different Pasture Pro g rams Pa g e 3Ma y 1999 Table 2. Means S q uares from Anal y sis of Breed x Pasture Pro g ram Subclass Means of Ad j usted Record. Sourced.f.Weanin g Rate Survival Rate Pre g nanc y Rate Breed of dam ( D ) 4 226.97* 247.16* 17.70 Breed of sire ( S ) 1 144.00* 1.78 128.50* Pasture pro g ram ( P ) 2 896.70* 751.03* 12.15 D x S 4 42.00 69.58 9.57 D x P 8 97.26* 93.51* 4.26 S x P 2 33.59 17.86 5.40 D x S x P 8 45.67 56.18 8.63 Error Pre g nanc y and wean 1632 40.02 43.07 -Survival 1188 --10.32 Si g nificantl y different at P ( .05 ) * Si g nificantl y different at P ( .01 ) .Replacement heifers were grown together fromincluded during both periods of the study. These breed weaning until being placed in their respective herds justgroups represented a total of approximately 300 matings prior to the breeding season at two years of age.per phase. There were no indications of interactions Cows were culled on the basis of repeated reproductivecombined analyses yielded unbiased estimates of effects. failure or failure to raise a calf.The error mean square used in testing significance was the mean of subclass numbers. The model for the combinedData AnalysesIndividual performance data were recorded annually for pregnancy status, calf survival, weaning rate, age of calf at weaning, weaning weight, 205-day weight, and market grade of calf. The research was conducted in two phases, five years each. The separate analyses for both reproduction and production traits are discussed. The observed data for pregnancy status, calf survival, and weaning rate were recorded as 1 or 0 (zero). These individual data were processed initially in separate analyses for each phase. Least squares techniques as outlined by Harvey (4) were followed, employing the same model for all analyses. All effects were assumed to be fixed. Since subclass numbers were approximately proportional the above analyses yielded efficient estimates of effects. A third analysis was performed by pooling data for the two phases. The least squares means for the breed x pasture program subclasses from the above analyses were adjusted for differences between phase and combined in a single analysis. The adjustments required were small for pregnancy and weaning rates and nil for calf suvival. The adjustment for combining the two phases into a single analysis was made on the basis of differences between phases for the two breed groups of F cows which were1between the two phases. Thus, it was concluded that the pooled error term for the two phases coded by the harmonic analyses for reproduction traits included breed of dam (D), breed of sire (S), pasture program (P) and their interactions (Table 2). The individual records for age of calf, condition score, 205-day weight, and weaning weight were first analyzed separately for the two phases, employing a model including year, mating groups (sire x dam), pasture program, sex, age of dam, and first order interactions. Secondly, the data from the two groups of F cows which were included across1both phases of the trial were analyzed employing a similar model. On the basis of these preliminary analyses records were adjusted for year, age of dam, and sex on a within-program basis. The adjusted data then were analyzed by least squares methods ou tlined by Harvey (4). The models utilized are indicated in Table 3.


Beef Production of Brahman, Shorthorn, and Their Crosses on Different Pasture Pro g rams Pa g e 4Ma y 1999 Table 3. Mean S q uares from Anal y ses of Ad j usted Records. Sourced.f.Weanin g A g eCondition Score205-da y Wei g htWeanin g Wei g htAnnual Prod / Cow Pasture pro g ram ( P ) 26,277 *588.1 *930,084* *1,398,182 *45,610 * Breed of dam ( D ) 46,101 *44.8 *377,104* *402,613 **15,100 * Breed of sire ( S ) 1274 42.1 *88,665 *81,920 * 1,015 P x D 8897 35.9* *14,987 *15,902 * 2,165 P x S 22,514** 3.4 4,496 5,060 1,200 D x S 41,651 1.7158,247 *263,831** 5,500 P x D x S 83,430* *17.4* 3,306 11,324* 890 Remainder 1209804 1.5 2,202 4,096 1,513a Error df for production per cow was 120.a* Significantly different at P (.05). * Significantly different at P (.01 ). Individual records of calves weaned were analyzed foraverages for the five breed groups of cows were: Brahman, all traits other than annual production per cow. In order to71%; 3/4 Brahman, 80%; F, 76%; 1/4 Brahman, 75%; obtain observations that approached normal distributionand Shorthorn, 64%. The observation that F and backcross more closely than a combination of individual zero andcows did not differ significantly was noted also by Koger weight records, annual production per cow was computedet al. (7) in a previous publication from the same station. for 150 year x program x breed-of-calf subgroups. This yielded five observations in each of the 30 breed of calf xThe significant (P < .05) breed of cow x pasture program groups. Analyses of these observations yieldedinteraction provides an example of one form of lower standard errors of estimates than analysis ofgenotype-environment interaction. This arose principally combined individual zero and weight records.due to differential response to improved pasture programs. pregnancy rate of 61% on native range versus 72% on theResults and DiscussionThe results from the combined analyses for both reproduction and productive traits are given in Table 2 and Table 3. Least squares means for reproduction are presented in Table 4 and for production traits in Table 5 and Table 6. Observed heterosis levels (percent advantage of crossbreeds over the mean of the two purebred breeds) are shown by pasture program in Table 5 and Table 6.Pregnancy RatePregnancy rate was significantly influenced by both pasture program and breed of cow as well as their interaction. The average pregnancy rates were 64%, 76%, and 81% for the native, combination, and improved programs, respectively. The rates of improvement ranked in the anticipated order. The performance on the improved area was somewhat lower than that reported by Gonzalez-Padilla et al. (3) and Crockett et al. (2) for south Florida. It is explained for the most part by the relatively low response of the purebred cows (Brahman or Shorthorn) to the improved pasture programs (Table 4). The overall1 1The Brahman and Shorthorn cows had an average highly improved program for a difference of 11%. For crossbred cows the averages were 67% and 86% for the same two programs for an increase of 19%. The effect of breed of sire on pregnancy rate was significant (P < .05), 76% for the Brahman and 72% for the Shorthorn with no significant breed of sire x pasture-program interaction.Calf SurvivalCalf survival from birth to weaning is an important factor affecting net productivity. The combined analysis for reproduction shows survival rate to be affected by breed of sire. Calves sired by Brahman bulls had an average survival rate of 94% while the survival rate of Shorthorn sired calves was 98%.


Beef Production of Brahman, Shorthorn, and Their Crosses on Different Pasture Pro g rams Pa g e 5Ma y 1999 Table 4. Avera g e Rates for Pre g nanc y Calf Survival, and Weanin g Classified b y Breed of Cow X Pasture Pro g ram and Breed of Sire X Pro g ram. Pre g nanc y Rate % Survival Rate % Weanin g Rate % Pro g ram Pro g ram Pro g ram 123Av.123Av.123Av. Breed of dam B617775719697969759757269 B3 698583809697969566847776 F1 618385769697969659818274 B1 7168877599100979871688475 S616269649594939458586460 Breed of sire B677785769496939463737972 S627778729998979862767671 Table 5. Breed X pro g ram least s q uares means for a g e at weanin g condition score, and 205-da y wei g ht for breed of calf, breed of sire, breed of dam, and crossbred advanta g e for different traits. Weanin g A g e Condition Score 205-da y Wei g ht Pro g ram Pro g ram Pro g ram 123Av.123Av.123Av. da y ss c o r el b s Breed of Calf B x B 2152222062147. B x B 2192232192207. x F 2212252252248.39.810.89.73874534884421B x B 2192142222188.28.810.39.13594184654141B x S 2232272382297. S x B 2042192342199.09.810.49.8382444441422 S x B 2202252332268.89.310.89.63794184334103S x F 2152272352268.810.211.210.13724354474171S x B 2172182122167. x S 2242252232246. Breed of Sire B 2192222222217.99.310.19.1350408438398 S 2162232272228.19.510.79.5336399416384 Breed of Dam B 2092202202178. B 2192242262238.49.310.49.33674134314043 F 2182262302258.610.011.09.93804434674301


Beef Production of Brahman, Shorthorn, and Their Crosses on Different Pasture Pro g rams Pa g e 6Table 5. Breed X pro g ram least s q uares means for a g e at weanin g condition score, and 205-da y wei g ht for breed of calf, breed of sire, breed of dam, and crossbred advanta g e for different traits. Weanin g A g e Condition Score 205-da y Wei g ht Pro g ram Pro g ram Pro g ram 123Av.123Av.123Av. da y ss c o r el b s Ma y 1999 B2182162172178. S 2232262302276. All g roups2182232252228.09.410.49.3343404426391 Advanta g e of crossbreds over purebreds % CalfDam FPB-30102154892018141713/4F1-1173219131433262527 3/83/40-26+121-18829202022 7/83/4-1-1101114518131113 Table 6. Breed X pro g ram least s q uares means for weanin g wei g ht, weanin g rate, and production per cow for breed of calf, breed of sire, breed of dam, and crossbred advanta g e for different traits. Weanin g Wei g ht Weanin g Rate Production Per Cow Pro g ram Pro g ram Pro g ram 123Av.123Av.123Av. lbs % lbs Breed of Calf B x B 35040439238256767970196307310271 B x B 372435453420657570702423263172953B x F 408489527475638381762574064273631B x B 379432497436717193782693074623461B x S 33241646740557527160189216332245 S x B 37746649344563746568238345320301 S x B 400451482444689285822724154103663S x F 383473501452547984722073744213341S x B 328400416381716575712332603122681S x S 24433838032159656961144220224196 Breed of Sire B 36843546742462717971231312370304 S 34642645440963757471219323337293 Breed of Dam B 36343544241459757269214326318286 B 386443467432668477762553723603293


Beef Production of Brahman, Shorthorn, and Their Crosses on Different Pasture Pro g rams Pa g e 7Table 6. Breed X pro g ram least s q uares means for weanin g wei g ht, weanin g rate, and production per cow for breed of calf, breed of sire, breed of dam, and crossbred advanta g e for different traits. Weanin g Wei g ht Weanin g Rate Production Per Cow Pro g ram Pro g ram Pro g ram 123Av.123Av.123Av. lbs % lbs Ma y 1999 F396481514463598182742343904213481 B 354416457409716884752522833843061 S 28837742336358586460167219271219 All g roups35743046141663737671224318351298 Advanta g e of crossbreds over purebreds % CalfDam FPB191925214-11-1-2266221713/4F133303332215201337485850 3/83/4311927252116292259376352 7/83/41813131418-15840111821 The average death loss of 4% observed in this study is lower than that reported from other studies in Florida (2, 6).Weaning RateWeaning rate is the product of pregnancy rate andstudy in add ition to using it for estimating weights at a survival rate. Since death losses were small in this trial,constant age of 205 days. the data on weaning rate (Table 4) closely paralleled those of pregnancy. The one exception of this trend pertained toPasture program and breed composition of dam breed of sire effects, which were highly significant forsignificantly (P < .01) influenced age of calf. Age of calf pregnancy but approximately nil for wean rate. Thisvaried from 218 days for Program 1 to 226 days for resulted from breed of sire effects being reversed forProgram 3 (Table 5). This trend reflected the possibility of pregnancy and survival rates.a shorter calving interval from calving to estrus in the The average weaning rate for the trial was 71%. Thefor the pure Brahman to 229 days for the F calves out of average for the three pasture programs was 63%, 73%, andShorthorn cows (P < .01). A long gestation period for 76%, respectively. The average weaning rates by breed ofBrahman cows along with a difference in interval to first cow were: 69% for the B; 76% for the BS; 74% for thepostpartum estrus likely entered into this difference (2, 9,31F; 75% for the SB and 60% for the S. 11, 12). These results also suggest that the Shorthorn cows13 1As was the case for pregnancy rate, the cow groups responded differently to the pasture programs for weaning rates. A good portion of the interaction effects resulted from the crossbred cows responding more to improved conditions than did the purebreds. The average weaning rates for the three groups of crossbred cows were similar, varying from 74% for the F to 76% for the BS cows.13 1Age of Calf at WeaningWhere mating occurs in a restricted season and calves are weaned all at one time, age at weaning is an important production trait, influencing the weight and value of calf produced. It was analyzed as a pr oduction trait in this improved program (8, 9). Age of calf varied from 214 days1which did conceive, did so early in the breeding season.Condition ScoreThis trait was included because it reflects thrift and vitality and generally is positively associated with prices received for calves. The calves were scored to the nearest one-third of a Federal market grade for slaughtered calves. Scores of 6, 7, and 8 were used to designate low, medium,


Beef Production of Brahman, Shorthorn, and Their Crosses on Different Pasture Pro g rams Pa g e 8Ma y 1999and high commercial, 9 to 11 for good, 12 to 14 choice, Breeding Brahman instead of Shorthorn bulls to etc. Shorthorn cows increased weaning weights 84 pounds, and As seen in Table 5, condition score was significantlycows increased weaning weights 63 pounds. influenced by pasture program (P), breed of dam (D), breedImprovements in weaning weights were also obtained when of sire (S), and P x D interaction effects. Progeny ofBrahman bulls instead of Shorthorn were bred to BS cows Brahman dams improved by one-third of a grade in(55 pounds) and Shorthorn instead of Brahman bulls to condition from Program 1 to Program 3, progeny ofBS cows (24 pounds). crossbred dams improved two-thirds of a grade, and the progeny of Shorthorn females increased by four-thirds of a Highly significant interaction of breed of calf with grade in the improved program. pasture program was observed (Table 6). This was due to Significant heterosis in the crossbreds was obvious foronly 32 pounds with improvement in pastures, whereas the condition score with estimates of 9% for F calves inShorthorn calves increased 136 p ounds. Backcross calves,1purebred dams, 14% for backcross calves on F dams, 8%BS and SB, responded similarly with increases of 1191for BS or SB calves on backcross cows, and 5% for SBand 118 p ounds for the two breed groups, respectively.5353 71and BS calves on backcross dams. Heterosis levelsInteraction of breed of dam with pasture program was71tended to be higher in the native pasture program than onhighly significant, with the response to improved pastures improved pastures for condition score.increasing as the proportion of Shorthorn breeding in the Brahman female produced as well on the intermediateWean Weight and 205-day We ightEstimated 205-day weight is a measure of growth rate, while weaning weight reflects differences in both rate of growth and age at weaning. In this study, the trends shown for pasture program and breed group differences were similar for the two traits (Table 5). Due to this similarity, the two traits will be discussed in conjunction. Significant main effects (P < .01) were found for pasture program, breed of dam, and breed of sire. Interaction effects for pasture program x breed classifications likewise were significant. Average weaning weight was 416 p ounds, varyingThis trait is a measure of total herd performance to from 357 p ounds on the native to 461 p ounds on improvedweaning. It includes weaning rate times weaning weight. pasture (Table 6). Brahman-sired calves exceeded thoseThe average pr oduction per cow was 298 p ounds, with sired by Shorthorn bulls by an average of 15 pounds.values for pasture programs varying from a low of 224 Weaning weights by breed of dam across all pasturepounds for the native range to 351 p ounds for the highly programs by ascending order were 363, 409, 414, 432, andimproved pastures (Table 6). Breed groups ranged from 463 pounds for the S, BS, B, BS, and F cows,196 p ounds for the pure Shorthorn to a high of 366 p ounds13311respectively. Weaning weight of calves from the F cowsfor SB calves on BS cows. Utilizing both breeds of1averaged 100 p ounds greater than that of the Shorthorn andsires, the F cow pr oduced 348 pounds compared to 329 49 pounds more than that of the Brahman, indicating a highp ounds for the BS cows and 306 p ounds for the SB degree of heterosis. Average weaning weights across allcows. Total production for Brahman and BS cows on the pasture programs, relative to breed of calf, were highest forintermediate pasture program exceeded that on highly the product of the F cow when sired by Brahman bulls, atimproved pasture.1475 p ounds, and lowest for purebred Shorthorn calves, at 321 po unds. Weaning weights dropped when eitherThe differential response of breed groups to the three Shorthorn or Brahman breeding in the calf exceededpasture programs followed the same pattern as that for calf three-fourths. The backcross calves, BS, and BS, out ofweights. The response to improved pasture was greater for5335BS and BS dams, were second only to the products ofcows with a predominance of Shorthorn breeding than for1331the F cows. dams predominately of Brahman breeding.1breeding Shorthorn instead of Brahman bulls to Brahman13 31a differential response of calves; the Brahman increased3131cow increased. An interesting feature was that the program as she did on highly improved pastures. Heterosis levels for calf weights were high. The advantage for crossbreds in weaning weights varied from 14% for BS and SB calves nursing 3/4-1/4 cows to 32%7171for the reciprocal backcross calves on F dams (Table 6).1Average heterosis levels for 205-day weight were slightly lower on the highly improved native (20%) than on native range (25%) but approximately equal (24% vs 25%) for the two programs for weaning weight.Annual Production Per Cow53 31 1 31 31 31


Beef Production of Brahman, Shorthorn, and Their Crosses on Different Pasture Pro g rams Pa g e 9Ma y 1999Heterosis levels observed for annual production perheavier 205-day and weaning weights for Brahman sired cow were high. The level of heterosis for the reciprocalcalves. Breed of sire effects were non-significant for age at 3/8-5/8 calves nursing 3/4 blood cows on improved pastureweaning and production per cow. However, mating system was 63%. The advantage of the F cows over the averagewas highly significant (P < .01) for production per cow.1of the purebred increased linearly with improvements inBreed classifications for both calf and dam showed pasture program, 37% for the native range, 48% for thesignificant (P < .01) first order interactions for all traits intermediate program, and 58% for the improved program.except for breed of dam x pasture programs for weaning Responses of this magnitude emphasize the utility of theage. Brahman and European crosses for improvement of production performance in environments where theCrossing the purebred Shorthorn and Brahman resulted improved temperate-zone breeds are not well increased weaning weights of 26% for calves of the They suggested also that Zebu-European crosses may haveShorthorn dams and 16% for the Brahman dams. Weaning utility under other conditions. weight of calves from F cows exceeded the average of the In these data, calf growth was positively associatedand 29% when sired by Shorthorn bulls. The advantage of with Brahman breeding, suggesting that the add itive effectsall crossbreds over the average of the purebreds was 1.5%, of the Brahman for adaptability to this area contributed to9.1%, 19.8%, 22.9%, 10.1%, and 34.8%, respectively, for growth of calf. age at weaning, condition score, 205-day weight, weaning The data for breed groups probably can best be interpreted in terms of: (1) additive genetic merit of the Significant interactions for breed of cow x pasture parent breeds involved, (2) climatic adaptab ility of theprogram was the result of F cows resp onding more to various breed groups, and (3) level of hybrid vigorimprovements in nutrition than the purebred groups. These influencing performance. F cows responded linearly in all traits with each increment appeared to be associated with growth, while ShorthornSummary and ConclusionFive breed groups of dams including Brahman (B), Shorthorn (S), 3/4 B-1/4 S (BS,), 1/2 B-1/2 S (F), and31 13/4 S-/ B (SB), each mated to both Brahman and1 431Shorthorn sires, grazed continuously on three different pasture programs. The pastures were native (P), a1combination of native and improved pasture (P), and all2improved pastures including irrigated clover-grass area (P).3Highly significant differences (P < .01) occurred in pregnancy rate and weaning rate for both breed of cow and pasture program. Pregnancy rates for Brahman sires were higher (P < .05) than for Shorthorn sires, but a higher survival rate (P < .01) of Shorthorn sired calves made weaning rate for sires non-significant. Average weaning rates by breed of dam were 69%, 76%, 74%, 75%, and 60% for B, B, F, B, and S cows, respectively. Weaning311rates for pasture programs were 63%, 73%, and 76% for P, P, and P programs, respectively.123Weaning age, condition score, 205-day weight, weaning weight, and production per cow variations were highly significant (P < .01) for pasture program, breed of dam, and breed of calf. Breed of sire effects resulted in higher condition scores for Shorthorn sired calves and1purebred progeny by 35% when sired by Brahman bulls weight, weaning rate, and annual production per cow.1 1of improvement in pasture programs. Brahman breeding breeding appeared to be related to degree of condition relative to pasture program.Literature Cited1)Cartwright, T. C., G. F. Ellis, Jr., W. E. Kruse, and E. K. Crouch. 1964. Hybrid vigor in Brahman-Hereford crosses. Texas Agr. Exp. Tech. Monogr. 1. 2)Crockett, J. R., R. W. Kidder, M. Koger, and D. W. Beardsley. 1973. Beef pr oduction in a crisscross breeding system involving the Angus, Brahman, and Hereford. Fla. Agr. Exp. Sta. Tech. Bull. 759. 3)Gonzales-Padilla, J. R. Crockett, M. Koger, and D. E. Franke. 1969. Straightbred vs. crisscross breeding systems in south Florida. J. Anim. Sci. 29:1:107. 4)Harvey, Walter R. 1960. Least-squares analysis of data with unequal subclass numbers. A.R.S. 20-8. U.S.D.A. Reprint, July 1968. 5)Koger, M., W. G. Blue, G. B. Killinger, R. E. L. Greene, H. C. Harris, J. M. Myers, A. C. Warnick, and N. Gammon, Jr. 1961. Beef pr oduction, soil and forage analysis economic returns from eight pasture


Beef Production of Brahman, Shorthorn, and Their Crosses on Different Pasture Pro g rams Pa g e 10Ma y 1999programs in north central Florida. Fla. Agr. Exp. Sta. Bull. 631. 6)Koger, M., J. S. Mitchell, R. W. Kidder, W. C. Burns, J. F. Hentges, and A. C. Warnick. 1967. Factorscalves. Fla. Agr. Exp. Sta. Tech. Bull. 624. influencing survival in beef calves. J. Anim. Sci. 26:1:205. 7)Koger, M., W. L. Reynolds, W. G. Kirk, F. M. Peacock, and A. C. Warnick. 1962. Repr oductionintervals from first exposure to conception and performance of crossbred and straightbred cattle onintervals from partuition to conception. J. Anim. Sci. different pasture programs in Florida. J. Anim. Sci.27:105-112. 21:1:14-19. 8)Peacock, F. M., E. M. Hodges, W. G. Kirk, and M. Koger. 1972. Forage systems in beef production. Soilin a subtropical environment.II.Gestation length in and Crop Sci. Soc. Fla. Proc. 32 (1972):5-7.Brahman ca ttle. J. Anim. Sci. 27: 101-104. 9)Peacock, F. M., M. Koger, E. M. Hodges, and W. G. Kirk. 1973. Beef ca ttle pr oduction as affected by breed composition and forage systems. Soil and Crop Sci. Soc. Fla. Proc. 33(1973): 27-29. 10)Peacock, F. M., W. G. Kirk, E. M. Hodges, W. L. Reynolds, and M. Koger. 1969. Genetic and environment influences on weaning weight and slaughter grade of Brahman, Shorthorn crossbred 11)Plasse, D., M. Koger, and A. C. Warnick. 1968a. Reproduction behavior of Bos Indicus females in a subtropical environment. III. Calving intervals, 12)Plasse, D., A. C. Warnick, R. E. Deese, and M. Koger. 1968b. Repr oductive behavior of Bos Indicus females