Compensatory Gain

8/8/2019 Compensatory Gain

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Compensa tory Gainby Br ian M. Freking, Will Lat hr op,

E lise Mitchell an d David Redha ge

2000 Beef P rogress Report -2


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C om p e n s a t o r y G a i n

TopicsAbstract

Experimenta l Procedures

Introduction

Results a nd Discussion

Implications

Literature Cited

F i g u r e sF igu r e 1 . H eife r We igh t s ove r Tim e - Yea r 1

F igu r e 2 . H eife r We igh t s ove r Tim e - Yea r 2

F igu re 3. H eifer Weigh ts over Tim e

F igu r e 4. P r egn a ncy P er cen t age Br ea kd own

F igu r e 5 . P r egn a n cy P er ce nt a ge by F ee d Tre at m en t Yea r

1&2

F igu r e 6 . Re br ee din g P er ce nt a ge by F eed Tr ea t m en t

Ta b l e sTab le 1. E fficie ncy I nd ex of H eifer s by M an a ge men t

Treatments

Ta ble 2. H eifer Developm en t Cos t/H ea d - Yea r 1

Ta ble 3. H eifer Developm en t Cos t/H ea d - Yea r 2

P a g e N o.i

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P a g e N o.3

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P a g e N o.5

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2000 by Kerr Cent er for Su sta ina ble Agricultu re, Inc.


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E v a l u a t i o n o f R e p r o d u c t i o n a n d C a l f P e r fo r m a n c e

o f B e e f H e i fe r s U n d e r M a n a g e m e n t

Wi t h a n d Wi t h o u t C o m p e n s a t o r y G a i n

Brian M. Frekin g, Will Lath rop, Elise Mitchell and Da vid Redha ge

The Kerr Center

for Su sta inable Agricultur e, Inc.

Poteau, Oklahoma

A b s t r a c t

A multiple year stu dy was condu cted using crossbred h eifers pr oduced on t he Kerr

Center Ranch including breeds consisting of Angus (AN), Senepol (SE), Gelbvieh (GV),

Brah ma n (BR), an d Bran gus (BN). Ea ch year, heifers were allotted at r an dom to

ma na gement tr eatm ents blocked within breed composition an d weight. The first tr eatm ent

supplements h eifers t o gain en ough weight during t he winter period to rea ch a breeding

ta rget weight an d minimize or eliminate compensa tory growth dur ing the spring green u p

period. All groups were bred t o calve first a s two-year-olds with n on-pregna nt an ima ls

culled after pregna ncy check. The second tr eat men t group will ta ke advan ta ge of

compen sat ory growth ut ilizing the spring green -up period an d supplement at ion. This

group was fed an en ergy supplemen t for only 60 days pr ior t o th e breeding dat e to reachtheir ta rget weight. The third tr eatm ent group consisted of heifers ma na ged to take

advant age of compensa tory growth during th e spring and su mm er period an d prima rily

rely only on gra ss as th eir sour ce of nu tr ition. Some supplemen ta tion of ha y was requ ired

for all groups for ma inten an ce growth dur ing the dorm an t season. The breeding period

began on Ma y 1 each year u tilizing A.I. for one h eat period after wh ich a clean -up bull was

used. The breeding season term inated on J uly 1 equat ing to a 60 day breeding season.

Reproductive perform an ce m easur es were evaluated on:C % CyclingC Ca lving difficult y scoreC DystociaC Pregnancy rat eC Calving int ervalC % Wean ed/cow exposed


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Growth per form an ce of th e heifer/cow an d th eir calves were evalu at ed on:C Average daily gain (ADG)C 205 day weightC 205 da y weight /cow exposedC Heifer weight over tim eC Cow weight at breeding, calving and weaning

Economics were evalua ted on:C Heifer development cost (feed, vet, medicine, etc.)C Income (market calves, replacements, and culls)


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E x p e r i m e n t a l P r o c ed u r e s

I n t r o d u c t i o n

It h as been est imat ed th at up t o 75% of th e feed ener gy needed for beef production is

requ ired by th e cow-calf segmen t of th e indust ry. Of th at , 70 to 75% is used t o cover cow

ma intena nce requiremen ts. As a r esult, factors a ffecting cow maint enan ce requirementscan be expected to affect overa ll beef production efficiency. The comp en sa tory growth of

catt le on past ur e following nu tr itiona l rest riction ha s been widely stu died (ODonovan,

1984; Ryan , 1990). In a ddition to increa sed efficiency, rela ted t o lower m aint ena nce

requirements and lower energy content of live-weight gain than in normal growing cattle,

increases in volunta ry herbage int ake is the ma in explana tory mechanism. Mana gement

ut ilizing compensa tory growth to reduce input s ma y have a significant im pact on a

producers bottom line.

This stu dy was condu cted at th e Cann on Multi Species Grazing Pr oject Area. Upon

fall wean ing heifers were tr eated a s norma l in our system a s report ed previously in th e

Kerr Cent er pr ogress r eport s. This included vaccina tions for five-way leptospirosis and

respirat ory IBR, PI 3, BRSV, blackleg and clostr idials. Heifers were also tr eat ed for int ern al

an d extern al para sites in th e fall. Upon ar rival they received a 12-14% protein supplement

for a t least a week to ease their t ra nsition from wean ing pens to pastu re an d to train

an ima ls to be coaxed when m oved for rota tional grazing. Newly wean ed heifers ent er th e

grazing program with the primary objective to have them gaining 1 lb./hd/d on grass with a

minim um of supplem ent ed feed to maint ain body condition (i.e., B.C.S.= 5). Heifers wererota ted every two to four da ys between pas tu res. Heifers were rota tionally gra zed from

weaning unt il the first par t of December a nd h ad a ccess to fescue/bermu da gra ss hay using

temporar y wire ha y traps.

Init ially, cat tle in th e first t rea tm ent (Feed Gr oup) received free a ccess to hay an d

were supplem ent ed with a 14% creep pellet an d cott onseed meal daily at a level predicted

to rea ch their ta rget weight outlined in the feeding time line. Feeding began on 12

December a nd completed on 2 April. Cat tle in the second trea tm ent (Flush Gr oup) receivedfree choice hay an d were supplemen ted with cott onseed meal. Sixty days prior to th e

breeding da te t his group r eceived a 14% creep pellet a s an ener gy sour ce for compen sat ion.

Feeding began on 1 March an d completed on 1 May. Catt le in the th ird trea tm ent (Grass

Group) also received supplemen ta tion of cottonseed mea l and ha y. This group had t o rely

on the spr ing green-up period to compen sat e for a limited winter n ut rition period.


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Initial weights were taken and heifers were sorted prior to being put on feed

tr eat men ts. Cat tle were also weighed periodically to evalua te compensa tory growth an d

ta rget weight s du ring critical periods of the production cycle.

Cost of production and income were kept separately for each treatment group.

Labor costs were only applied to norm al pr oduction pra ctices.

Data was an alyzed using Least Squa res Means pr ocedures of SAS. The model

includes cont inuous effects of ma na gement t rea tm ent a nd breed composition. At th e

present t ime, results are pr eliminar y, and furt her st atistical an alysis is needed.

R e s u l t s a n d D is c u s s io n

The objective of th e st udy is t o evalua te r eproduction, economics and calf

performance in heifers developed with and without compensatory growth. Compensatory

growth is the grea ter tha n expected weight gain sometimes seen in a nima ls following an

extended period of slow growth or weight loss due to rest ricted nut rition. Compen sat ory

growth is a complex met abolic fun ction a nd a nu mber of mecha nism s ar e involved

(Carst ens, 1995). This paper does not at tem pt t o find out how compensa tory growth occurs

but r at her , find out how to optim ize its function t o th e producers adva nt age.

Growth rate (Fig. 1) differences over time among the feed treatments help

gra phically illust ra te cat tles adapt at ion to feed resour ces. In Septem ber heifers werewean ed and weights collected. These weight s and t heir genotype deter min ed which feed

tr eatm ent a nima ls were ra ndomly assigned. Weight at wean ing was designed to be similar

initially between treat ment s. Although th e groups were ma na ged the sam e from weaning

unt il December, only the gra ss group ma intained th eir weight in th e first year. This is

somewha t of a m ystery and ma y just be ra ndom error with in the year.

The second year followed a m ore pr edicted growth curve (Fig. 2). The gra ss group

also showed examp les of compen sat ory growth dur ing their developmen t. It is illustr at edby a flat slope on th e growth curve followed by a sha rp r ise. A key point t o emph asize is

the t iming of this compensa tory growth. It is importa nt tha t h eifers weigh enough to reach

puber ty an d be gaining weight going into breeding season. Weight h as been shown to be

positively corr elated with r eproductive tr aits su ch as pregnancy rat e an d percent br ed

ar tificially (Taylor, 1984).


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Figure 1.Heifer Weights over Time- Year 1

FeedGroup

60 DFlushBreedingDate

Pregnancy

Check

550600650700750800850900

Weigh Dates

Feed Group

Flush Group

Grass Group

9/16/96 10/15 11/15 12/12 1/15 2/27 3/15 4/2 5/1 6/5 7/9 8/12 9/9 10/1

546 568 629 662 694 748 792 824 857

549 580 613 638 680 742 782 821 854

536 537 596 603 635 696 737 777 801

Weight (lbs)

Figure 2.Heifer Weights over Time- Year 2

FeedGroup

60 DFlush

BreedingDate

PregnancyCheck

550600650700750800850900950

Weigh Dates

Feed Group

Flush Group

Grass Group

9/16/97 10/15 11/15 12/04 1/15/98 2/27 3/26 4/27 5/30 6/30 7/9 8/6 9/03 10/2

517 565 645 669 736 845 877 889

516 556 548 608 692 798 832 841

516 559 555 625 691 799 835 850

Weight (lbs)


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Figure 3. Heifer Weights over Time

FeedGroup

60 DFlush

BreedingDate

PregnancyCheck

WeaningCalving

9/16/96 12/12 5/1 8/12 10/1 4/29/98 8/25

600

700

800

900

1,000

1,100

Weigh Dates

Weight (lbs)

FeedGroup FlushGroup GrassGroup

Research ha s shown tha t h eifers n eed to weigh 60-65% of their ma tu re weight at th e

tim e of bre eding an d 80-85% at calving time for optim um re pr oductive efficiency. Our cows

usu ally weigh 1150 lbs. at 4 year s of age. Ther efore r eplacing th ose cows using th e ta rget

weight system we need our heifers to weigh 690-745 lbs. at br eeding an d 920-978 lbs. at

calving. On average all heifers met t heir ta rget weight at breeding the second year but

only the feed group a tta ined their t ar get weight a t breeding in year one. Weight a t calving

(Fig. 3) was collected a t bra ndin g which is 60 days pa st t he a verage calving dat e. Only the

gra ss group didnt r each th e second tar get weight of 920 lbs. at calving. This group had a n

aver age weight of 900 lbs. at calving. Cow weights wer e also recorded a t wean ing to

calculat e an efficiency index. The index (Table 1) is calculated a s th e adjust ed 205 day

weight of calf divided by cow weight to th e power (met abolic body size). Nu tr itionist s use

met abolic body size to deter mine an an imals daily nu tr ient requirem ent s. Using th is

index makes a n a ttem pt t o consider ma intena nce requirements tha t sh ould favor selection

of the most efficient animals regardless of cow size.


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Ta b l e 1. E f fi c ie n c y I n d e x of H e i fe r s b y M a n a g e m e n t Tr e a t m e n t s

Feed Group

n=29

Flush Group

n=29

Grass Group

n=29

Overall

n=87

0 Birth dat e 2/22 3/2 2/28 2/27

BW (lb) 73 70 71 72

Calving Ea se

Score

16.9 12.9 13.1 14.7

Actua l WW (lb) 460 423 422 436

Adj 205 d Wt (lb) 551 526 526 535

Cow Wt @WW

(lb)

997 1020 966 994

Efficiency Index 312 254 305 290

The feed group had the earliest average birth date which could also help explain the

hea vier wean ing weights. This group also ha d the highest nu mer ical calving ease score.

The lowest score possible is 11 (most desira ble) an d th e highest score is 55. Her itability

ha s been estima ted to be 0.30 for t his tr ait (Taylor, 1984). If producers recorded t his

inform at ion th ey could mak e substa nt ial impr ovement s. This scoring system is based on

th e Na tional Cat tlemen s Beef Association red book st an dar ds. The efficiency index shows

th e feed group being 7.6% more efficient th an avera ge followed by th e gra ss group a t 5.2%

above average. The flush group ha d the light est calves at weaning. This is primar ily due

to the fact tha t a verage birt h da te is later resulting in more calves sired by the clean-up

bull. They were also 12% less efficient t ha n a verage becau se of th e weanin g weights a nd

cow weights a t wea nin g. Br eed of sire expla ins over 80% of th is decrea se in efficiency (A.I.

vs natural).

Reproduction h as been em pha sized as a critical component of profitability in beef

operat ions. One objective of the stu dy is to evalua te differen ces in r eproductive componen ts

between feed treat ment s. In year one the overall pregnan cy rate was 85.3 % an d in yeartwo, 70%. Our local veterina rian deter mined pregnan cy statu s by rectal palpation. He also

at tempt ed to determ ine pregnancy stat us in days. Pr egnancy diagnosis was completed in

early September equating t o a potent ial gestat ion length of 100-120 days after bull tur n-

out. Based on the veter inar ians call it was calculat ed tha t th e percent bred A.I. was 81.6


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F i g u r e 4 . P r e g n a n c y P e r c e n t a g e B r e a k d o w n

# He i f e r s = 87

0

2 0

4 0

6 0

8 0

1 0 079 .3 81 .6

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P e r c e n t a g e

P e r c e n tP r e g n a n t

P e r c e n tA.I .

P e r c e n tC lean -up S i r e

P e r c e n tCa lved A .I .

Figure 5. Pregnancy Percentage by Feed TreatmentYear 1&2

0

20

40

60

80

10084.6

75.4 73.2

Percentage

FeedGroup

FlushGroup

GrassGroup

percent (Fig.4). Fina l determ inat ion of conception t o A.I. bulls was det erm ined by

calculating gestation length from calving date and A.I. date.


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F i g u r e 6 . R e b r e e d i n g P e r c e n t a g e b y F e e d T r e a t m e n t

0

2 0

4 0

6 0

8 07 2 .4

6 8 .9

5 8 .6

6 6 .7

P e r c e n t a g e

F e e dG r o u p

F l u s hG r o u p

G r a s sG r o u p O v e r a l l

Pr egnancy rat es between tr eatm ents was h ighest for th e feed group followed by the

flush group (Fig.5). The gra ss group had t he lowest percent of pregna nt h eifers in a sixty

day breeding season. This is combined dat a over two breeding seasons. Pr egnan cy ra tes

on a verage were very acceptable among all tr eatm ents. However, var iation between years

does exist between tr eatm ents.

Most pr oducers agree th at the difficult t ask of heifer m an agement is getting t hem

rebr ed following calving (Fig.6). We were pa rt icular ly int erest ed in h ow previous

ma na gement affected rebreeding. A recomm ended ma nagement pra ctice is to separa te

heifers from th e mat ur e cow her d and feed accordingly. Anoth er recomm enda tion is to

ha ve heifers calve about 30 days prior to the rest of th e cow her d. The rea son for this is

tha t 1 st calf heifers ar e still growing an d need a h igher plan e of nu tr ition. It a lso gives

heifers more tim e to rebreed. We felt we could mak e more int ense selections if all groups

were put un der the str ess of th eir natu ra l environm ent a nd select th ose animals tha t were

the most efficient. Therefore heifer management was similar between treatments following

th e first br eeding season. All heifers were comm ingled with th e ma tu re cows once they ha d

calved. They were rota tionally gra zed every two to th ree days. One poten tial difference

not account ed for is calving date. This can be ana lyzed as a covar iate var iable.

The overa ll rebr eeding rat e was 66.7 percent . This inform at ion is critical if a


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producer want s to ma intain a set n umber of cows. These rates determ ine how man y

replacement s need to be kept each year to mainta in herd size. If a producer wan ts a h erd

size of 100 cows he m ust keep ba ck enough heifers to repla ce those tha t a re culled for

var ious rea sons and th ose tha t dont rebr eed. Using our overall data of 79.7% pregna ncy

rate, 66.7% rebreeding rate and a herd size of 100 cows with a 15% replacement rate, wewould n eed to keep a min imu m of 28 heifers ea ch year (15 head 0.797 0.667 = 28).

Among treat ment s th e highest rebreeding ra te was in th e 60 day feed group followed by the

flush group. It was somewha t expected th at t he gras s group would be last consider ing their

plane of nut rition. Using these numbers a nd th e same goal of a 15% replacement ra te on

100 hea d of cows we would n eed 24, 29, an d 35 repla cement heifers for t he feed, flush, a nd

grass groups respectively to ma intain herd size. Pr elimina ry inform ation suggests a n

advant age to the feed and flush groups as a replacement heifer development str ategy.

A fina l study objective is to evalua te th e economics of each tr eat men t. Developmen t

costs were recorded for each tr eat men t. Individual cost item s are listed in tables two an d

th ree. The ma in differen ces to be gleaned from th e ta bles is th e feed, A.I., an d inter est cost.

A calf cost wa s a ssigned t o each trea tm ent based on a stan dar dized perform an ce an alysis

(SPA) cost t o ra ise a calf to weaning th at needs t o be recovered. This dat a can a lso be

inter pret ed tha t we need to sell heifers for aroun d $529 to brea k-even. Looking at it

an oth er wa y, if we could buy similar genetics for less t ha n $529 we should not ra ise our

own replacement s.

Looking a t t he overall cost for ea ch tr eat men t pr obably doesnt t ell the wh ole story.

We should be interested in wha t it cost per pregnant anima l since that is our goal

economically and biologically. Using th e pregna ncy rat es in figure 5 we can deter mine t he

cost/pregna ncy. The feed group h as a developmen t cost of $652.15 per h ead wh en cost is

divided by percent pr egnan t. The cost of th e flush group a nd gra ss group is $704.17 and

$692.65, respectively.


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Tab le 2 . He i f e r Deve lopm en t Cos t / Hea d- Yea r 1

Feed Group Flush Group Grass Group

# head 35 35 41

Calf Cost 316.92 316.92 316.92

Vet . & Medicine 10.58 10.58 10.58

Feed, hay, minera ls 69.45 62.26 41.77

Pasture ren t 28.25 28.25 28.25

Labor 6.08 6.08 6.08

Miscellaneous 34.41 34.41 34.41

A.I. 22.63 17.49 18.44

Clean-up bu ll 5.94 5.94 5.94

In terest (8% annua l) 39.54 38.55 36.99

Tota l Cost $533.80 $520.45 $499.38

Tab le 3 . He i f e r Deve lopm en t Cos t / Hea d- Yea r 2

Feed Group Flush Group Grass Group

# head 30 30 30

Calf Cost 316.92 316.92 316.92

Vet . & Medicine 10.58 10.58 10.58

Feed, hay, minera ls 75.15 62.24 36.25

Pasture ren t 34.84 34.84 34.84

Labor 6.08 6.08 6.08

Miscellaneous 34.41 34.41 34.41

A.I. 34.80 21.60 22.80

Clean-up bu ll 14.67 14.67 14.67

In terest (8% annua l) 42.20 40.11 38.12

Tota l Cost $569.65 $541.45 $514.67


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I m p l i c a t i o n s

A multitu de of options exist for developing heifers. Based on th ese prelimina ry

nu mber s it pays us t o feed th e heifers for r eproductive efficiency. Using our curr ent

inform at ion pr oducers could sort off th e top 30% of th eir heifers a t wea ning a nd feed th em

like th e feed treat ment group t o mainta in herd size. The rest of the replacements couldta ke a dvan ta ge of the efficiencies of compen sat ory growth to save economically. Anoth er

option m ight be to sort the lightest h eifers t o be fed as the first t reat ment group, an d ut ilize

adva nt ages of compen sat ory growth in t he lar ger heifers since th ey would not need t o gain

as mu ch t o reach th eir ta rget weight. One additiona l opportu nity might be to improve our

fora ges an d gra zing efficiencies to supply a better year -roun d nut rition progra m. Our da ta

also shows the imp ort an ce of good nu tr ition when ut ilizing art ificial insemina tion. Another

aspect n ot covered in th e stu dy is the opport un ity for im provement by selection.

Herita bility for reproductive tra its generally are low in m agnitude, but trem endous

progress can be ma de if selection is emph asized in this a rea .

L it e r a t u r e C it e d

Carst ens, G.E. 1995. Symposium: Int ake by feedlot cat tle. Oklahoma Stat e University.

P-942: 70-84.

ODonovan, P.B. 1984. Compen sat ory gain in cat tle an d sheep. Nu tr ition Abstr acts and

Reviews, Series B, 54: 389-410.

Ryan, W.J. 1990. Compensa tory growth in cat tle and sheep. Nut rition Abstra cts andReviews, Series B, 60:653-664.

Taylor, R.E. 1984. Beef Pr oduction and t he Beef Indu str y: A Beef Pr oducers Per spective.

Macmillen, pp.107-119.

Compensatory Gain

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