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Beef Production > Exam 3 > Flashcards

Exam 3 Flashcards

1
Q

job description for beef cow

A

she must breed, calve, milk sufficiently to feed her calf, breed back to calve in 365 days, produce claves that are in demand, do all this on your type of forage, pay for all her groceries and part of yours.

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2
Q

which breed is best? which cow size is best?

A

No one correct answer, environment is important. ln general, if quantity and quality of feed is abundant then large cow size with high milk potential is possible. If sparse nutritional conditions exist, then moderate size with lower milk production probably best.

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3
Q

consumer requirements

A

high lean to fat ratio. select to choice quality grade.

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4
Q

packer requirements

A

650-850 lb carcasses = 1000 -1350 lb live. steer = choice grade @ ~80% of avg. mature wt of sire and dam. Also steer = choice grade @ ~same wt as dam when sire and dam are about same frame size. (A cow with a body condition score of 5 is equivalent to her steer calf at choice grade).

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5
Q

feeder requirements

A

wants animal that grades low Choice at 1100-1200 lb. highest proce with yield grade 2-3 choice. go over 4 and you get docked ~$15-20/cwt.

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6
Q

cow-calf producer requirements

A

produce a heavy calf from a small cow. cost correlated to weight. ~70% choice. (BF = .4-.5 in).

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7
Q

Back fat

A

.4-.5 = ~70% choice. measure BF between 12-13 rib and ~5 in from top.

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8
Q

fat deposition

A

internal, subcutaneous, intermuscular, and intramuscular (marbling).

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9
Q

comparing large frame cattle to smaller framed cattle

A

At any given wt, large framed cattle gain faster (more on linear curve). At a given wt, nutrient requirements of growing/finishing cattle are greater for large framed cattle. when fed to a constant wt, large framed cattle will gain faster and have better F/G. When fed to a constant carcass composition, (.4-.5” BF) large framed cattle usually are less efficient, will have only a slight advantage in ADG, and prob wont have any advantage in days on feed (my even take 2-3 week longer). When fed to same carcass comp, stockered yearlings will be 100-200 lb heavier than calves placed immediately in feedlot.

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10
Q

nutrient requirements

A

NEm directly related to wt: NEm = .077W^.75. NEg related to sex, frame size, mature size (calf, yearling, compensating), body fatness. CP relationships similar to NEg.

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11
Q

NEm equation

A

Burn maintenance energy. Heat dissapation is proportional to the surface area of your body, and the weight in kilogram raised to the .75 is an equivalent value of surface area.

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12
Q

when choosing a breed, consider

A

Select something you like. cost and availability. Maternal traits this breed offers in a crossbreeding program (milk, bw, age at puberty, ability to breed back). Are they marketable in your area? Adaptable to climate they will live in (maintain body condition, quanity and quality of feed, how much suppl feed needed). Disposition. Body size and milk prod important factors that help determine feed requirements for cow and weaning weight of calf.

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13
Q

energy required increases

A

As milk production increases. And as cow size increases. increase wt 100 lb = increase maintenance 6-8%.

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14
Q

bigger cows require better management

A

greater maintenance requirement. usually are less fertile (prob related to nutrition). frequently have more calving difficulties.

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15
Q

greater milk production is not always desirable

A

Most beef cows avg. 10-12 lb milk/day, avg conversion = 1lb calf gain/10 lb. milk. Conversion rate by calf decreases as milk consumption increases. one study: net $ return favored ~14 lb milk/day (this will wean !550 lb calf with adequate forage). Too much milk is correlated with poor reproduction, calves often contract milk scours (be dehydrated), and cows predisposed to mastitis.

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16
Q

no way to recommend ideal cow type

A

Producer must determine what is the heaviest milking cow type that can consistently rebreed with the most likely feed resources, grown and purchased, that can be provided. Depends on availbale feed resources, cost of producing feed, amount of suppl feed purchased, and expected ww and calf prices.

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17
Q

small cows can wean heavier calves

A

Use moderate size cow (900-1100 lb 3+ tp 5 frame). Select dams for high maternal performance. Select sires for growth and carcass traits. Increases growth = it is more efficient to have larger sires than larger cows (but this will usually increase dystocia). can wean 500-600 lb calves with excellent feedlot and carcass performance. Need source for replacement heifers

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18
Q

compared to straightbred, crossbreds have greater return on investment.

A

Heterosis increases lb calf weaned/cow exposed ~20%. 65-75% of this increase is due to increased fertility. 25-35% of this increase is due to increased growth rate of calf and increased milk from cow (= increase WW). Growth weight and milk production have high heritability and low heterosis.

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19
Q

British breeds (compared to exotics)

A

Mature and fatten at lighter marketweights (1200-1350 lb). grow slower, smaller mature size. less muscular. more fertile. fewer calving difficulties. live and reproduce longer. used as maternal breeds in crossbreeding programs.

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20
Q

continental exotoc breeds (compared to british breeds)

A

large mature size (1350-1400 lb at market weight). later maturing. heavier muscled, this higher yielding carcasses. less fertile. increased calving problems. less marbling, thus lower quality grades. normally used as sire breeds in crossbreeding. some of the more fertile, moderately sized exotics are used as both sire and dam breeds (Gelbvieh and Saler).

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21
Q

Brahman and Brahman derived breeds

A

heat tolerance. have sweat glands. thinner hide. increased sa. parasite tolerance. crosses with british and exotics produce high heterosis. Undesirable characteristics are nervous disposition, pendulous sheath, meat is tough (>25% brahman, partly bc they cant be slaughtered w/out agitation or excitement, more connective tissue in the muscle of brahman cattle). not adaptable to cold climates.

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22
Q

importance of sire selection

A

one of the most important decisions producer will make. decisions havbe long term impact: calving ease, maternal ability, growth, carcass merit (minor importance bc you dont get bonus for marbling).

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23
Q

Sire selection: producer must…

A

Set goals. accurately assess current and desired genetics (breed makeup, production level of herd (need good records), determine frame size and weight (650-800 lb carcass)). assess management (forage base and need for stored feeds). determine marketing goals. Understand EPDs and how to use them. Keep up with selection technology.

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24
Q

most genetic progress is through the sire.

A

limited opportunity for genetic progress through females (low selection intensity - large portion of potential replacements must be retained), logevity is important, genetic info for heifers is limited: EPDs have low accuracy. By contrast, amount of genetic info available for sires can be overwhelming. number of progeny from sires increases accuracy of info. last 3 sires impact 80-90% of genetic progress in a herd.

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25
Q

selection intensity

A

% you have to save as replacement

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26
Q

genetics is important but not everything

A

P = G + E. G is permanent, E is temporary. Calf WW = “growth genes” + management, milk, forages and other nutrition, weather, health

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27
Q

important phenotypic or visual characteristics

A

overall balance and eye appeal. muscling. topline. feet and leg structure. testical/udder characteristics. eye characteristics. teeth. temperament.

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28
Q

what are EPDs?

A

an estimate of how a particular bull’s calf will perform in certain traits compared to another bull’s, in that particular breed and when bred to similar females, before the mating ever occurs. EPD value is calculated using info submitted to the association and provides a basic representation of the pedigree for that particular bull for a particular trait of interest. Cant use EPDs across breeds without adjustment values. EPD values are not static, they will change over time as more and more progeny info is collected. Best tool we have to predict genotype of an individual.

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29
Q

definition of expected progeny difference

A

the expected difference in performance of progeny of a particular bull when compared to the average progeny performance of all bulls evaluated in a breed. EPD values are expressed in same units that traits are normally messured.

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30
Q

expected progeny differences

A

do not predict performance. predict differences in performace. are as good as the data going into the system (honor system). currently, best predictor of genetic worth. do change, not static. cannot be compared across breeds without adjustment.

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31
Q

comparisons of EPDs made 3 ways

A

compare with another animal. comapre with the breed average. compare individuals with average EPDs of all animals born in the same birth year.

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32
Q

EPDs are predicted for:

A

bulls, cows, and non parents

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33
Q

angus

A

most popular breed. moderate size. good meat quality. do tend to be a little more nervous. bulls in range are territorial.

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34
Q

hereford

A

2nd most popular. very fertile - can calf under limited nutritional condition.
low milk production. susceptible to pink eye and cancer eye. sunburn udders. very goof in range situations.

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35
Q

polled hereford

A

less popular than regular hereford. more pendulous sheath. low muscle in rear end. polled dominant over horned.

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36
Q

shorthorn

A

1st breed. very popular around WW2. 3 coat colors - red, roan, white. additive gene. popular when fat was an important commodity. docile. British.

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37
Q

red angus

A

red is recessive. not alot of differences in production vs angus

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38
Q

limousin

A

continental. moderate size. highest yield grades of any cattle. heaviest muscle of common breed. dont grow particularly fast. not great milk. not very fertile. 5th -6th most popular. light skin around muzzle, eyes, and back of legs

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39
Q

charolais

A

fast, lean growth. good grade carcass. light milk. 1st of continental cattle to come over here.

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40
Q

simmental

A

larger, red and white. heaviest milking of beef breeds. grow fast. the more white you have, docked more.

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41
Q

galbvieh

A

moderate size. lbs calf weaned / lb bred = #1. high milk production. muscular. marble well. heavy dulap (neck). generally more white on legs and yellowish than limousin.

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42
Q

gelbray

A

popular cross

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43
Q

pinzgauer

A

white down back, rear end, and underneath. good maternal characteristics.

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44
Q

chianina

A

white with black muzzle, switch, and hooves. largest frame size in world. few calving difficulties. in late 70s-80s popular steer show.

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45
Q

maine-anjou

A

big as chianina. too large on maternal side. extreme calving difficulties (calves ~150 lb). work well in terminal cross.

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46
Q

salers

A

moderate size. cherry color. good milking. disposition problems. heavy hair coat.

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47
Q

brahman

A

several breeds of brahman. have sweat glands. thinner and excess skin. more parasite resistant. fertility isnt as high as other breeds. milk is little low. when crossed, heterosis is tremendous. very pronounced naval and pendulous sheath.

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48
Q

brangus

A

3/8 brahman and 5/8 angus. angus’ carcass and fertility traits.

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49
Q

santa gertrudis

A

1st breed developed in US. Brahman / shorthorn cross. popular up until 60s. not particularly milk well.

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50
Q

beefmaster

A

brahman / shorthorn / hereford cross. rated very well at meat research center. all kinds of colors and spots. preferred light brown color.

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51
Q

modern longhorn

A

light muscled, dont gain as well, more of a hobby breed

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52
Q

highland

A

scotland

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53
Q

hereford angus

A

black baldy, very good breed

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54
Q

crossbred

A

3 breed cross = 87% heterosis. 2 breed cross = 67% heterosis. 4 breed cross = 92% heterosis. if you dont follow plan, lose heterosis.

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55
Q

GE

A

groos energy, total energy in product

56
Q

DE

A

digestible energy

57
Q

ME

A

metabolizable energy; represents energy available for use

58
Q

NE

A

net energy. NEm is lost as heat. NEg is energy deposited as growth. NEm is priority and it is more efficient than growth.

59
Q

GPD

A

gaseous products digestion

60
Q

HI

A

heat increment, lost as heat

61
Q

GE - ____ = ____

A

GE - FE = DE

62
Q

DE - ____ = ____

A

DE - GPD - UE = ME

63
Q

ME - ____ = _____

A

ME - HI = NEm (65-70%) + NEg (30-40%)

64
Q

how are EPDss determined?

A

North American Cattle Evaluation Program (NACE). UGA, Colorado St, or Cornell. most breed assoc belong. Best linear unbiased prediction (BLUP), equations used to analyze data, accounts for trait h^2, accounts for genetic relationships among animals, considers genetic correlations among traits, corrects for genetic worth of cow used.

65
Q

heritability (h^2)

A

it is the portion of the phenotypic (observed) variation in a trait which can be attributed to genetic causes. % difference du eto genes.

66
Q

heritabilities for beef cattle traits

A

can never be standardized bc you can never get rid of envirnoment. higher heritability = faster change. low heritability = chanegs due to environment.

67
Q

calving ease heritability

A

.11 - .15

68
Q

pelvic area heritability

A

.15 - .25

69
Q

birth weight heritability

A

.25 - .35

70
Q

weaning weight heritability

A

.20 - .30

71
Q

yearling weight heritability

A

.30 - .40

72
Q

carcass traits heritability

A

.50 - .70

73
Q

scrotal circumferance heritability

A

.50 - .70

74
Q

heritability and selection potential for reproduction

A

heritability is low, selection is poor. moe heterosis

75
Q

heritability and selection potential for performance

A

heritability is moderate, selection is good

76
Q

heritability and selction potential for carcass

A

heritability is high, slection is excellent. low heterosis

77
Q

heritability and selection potential for scrotal circumferance

A

heritability is high, selection is excellent. low heterosis.

78
Q

EPDs based on genetic ties among herds

A

usually from sire end, contempoary groups

79
Q

contemporary group

A

group of animals with the same her, sex, birth season, weigh date, and management. the largest contemporary group is at birth, all subsequent traits are subsets of the birth contemporary group. (smaller the number the less accurate). correct id of contemp groups are essential to partition genetic effcts from environmental effects. P = G + E. CG is the way that the effect of E is estimated. If GC is wrong, then E is wrong, and EPD value is wrong. Must report all data, even the tail enders.

80
Q

correlated response

A

a genetic correlation between two traits is caused when some genes affecting one trait also affect another trait. can be a positive or negative response.

81
Q

animals with heavy WW have ___

A

heavy YW

82
Q

animals with heavy WW and YW have ___

A

heavy BW

83
Q

animals with rapid growth will have

A

larger SC and REA

84
Q

animals with high growth EPDs will have

A

lower maternal milk EPDs

85
Q

animals with high maternal milk EPDs produce

A

progeny with more marbling

86
Q

bulls with high SC will produce

A

daughters that mature early.

87
Q

EPD values are dependent on

A

individuals own record, ancestors and prgenys records, heritability of the trait, and genetic correlation of that trait with other traits.

88
Q

direct trait

A

sire’s direct affect on the calf

89
Q

maternal trait

A

traits a sire gives his daughters that influence how they produce

90
Q

all breeds have EPD values for

A

BW, WW direct, Milk (maternal), milk and growth, and YW

91
Q

WW due to milk

A

milk = milking ability of a bulls daughters expressed as lb of calf WW (not lbs of milk)

92
Q

WW due to milk and growth

A

WW of a bulls daughters calves. reflects milking ability of bulls daughters and the calves growth potential. calculation = 1/2 WW direct + “milk”

93
Q

direct calving ease

A

relative ease in which an individual’s calves are born to first calf heifers compared to all other individuals evaluated in breed. ability of calf to be born. can be expressed as a deviation of the percent of unassisted births or as a ratio.

94
Q

maternal calving ease

A

relative ease with which an individual’s daughters calves are born compared to al lother individuals evaluated in a breed. ability of a daighter to have a calf. can be expressed as a deviation of the percent of unassisted births or as a ratio

95
Q

gestation length

A

expected difference in average gestation length (expressed in days) of an individuals calves as compared to all other individuals evaluated in a breed. can be a predictor of calving ease and/or birth weight.

96
Q

birth weight

A

expected differences in average birth weight (expressed in pounds) of an individual’s calves as compared to all other individuals evaluated in a breed. can be a predictor of calving ease.

97
Q

weaning weight (also WW direct)

A

expected difference in average 205 day wight (expressed in lbs) of an individual’s calves as compared to all other individuals evaluated in a breed. this will evaluate an individuals ability to pass on genes for growth.

98
Q

milk (maternal milk)

A

expected differences in average 205 day wight of an individual’s daughters’ calves (expressed in lbs) due to the daighters ability to milk as compared to all other inividuals’ daighters evaluated in a breed. This is a predictor of added WW of calves due to the daughters ability to milk…not the lbs of milk she will produce.

99
Q

milk and growth

A

expected differences in average 205 day wight (expressed in lbs) of an individual’s daughters’ calves due to both the growth of the calf and the milking ability of the dam as compared to all other individuals’ daughters evaluated in a breed. also reported as combined, maternal weaning, maternal, or total WW. calculated as half of the direct WW EPD plus all of the maternal milk EPD.

100
Q

yearling weight

A

highly correlated wiyh BW and WW. expected difference in avergae 365 day weight (expressed in lbs) of an individual’s calves as compared to all other individuals evaluated in a breed. this trait is evaluated as post weaning gains. YW EPD = WW EPD + PWG EPD. if YW EPD is less than WW EPD, post weaning growth is negative.

101
Q

yearlin hip height

A

expected difference in average yearling hip height (expressed in in) of an individuals calves as compared to all other individuals evaluated in a breed. can be a predictor of frame score

102
Q

scrotal circumferance

A

expected difference in average yearling scrotal circumferance (expressed in cm) of an individuals calves as compared to all other individuals evaluated in a breed. bulls with high SC EPDs have dughters that mature early. Sperm production. minimal for yearling ~32 cm.

103
Q

carcass traits

A

expected difference in average carcass traits of an individuals calves as comapred to all other individuals evaluated in a breed. only a few breeds have carcass traits EPDs. only a few bulls within a breed have carcass traits EPDs. 12th rib fat, ribeye area, marbling, cutability are usual traits. can be based on ultrasound or progeny carcass data.

104
Q

mature size

A

expected difference in average mature size weight (expressed in lbs) or mature height (expressed in inches) of an individuals daughters mature size as compared to all other individuals daughters evaluated in a breed. found in the angus breed

105
Q

accuracy

A

a measure of certainty associated with each EPD. accuracy values range from 0-1. values closer to 1 indicate ahigher level of certainty. if ACC = .70 EPD might change dramatically with additional progeny data. if ACC = .90, EPD will change very little as new data become available. is a reflection of the amount of info which had gone into the EPD prediction.

106
Q

quantitative

A

traits affected by many genes

107
Q

possible change in EPDs

A

given an accuracy value, provides a confidence range of EPD values in which the “true” EPDs will lie. for most animals, the “true” EPD value will be in this range. a measure of the expected change a producer can expect in an individuals EPD values. another way to assess risk of using a particular animal.

108
Q

sources of info on an individual and acc

A

individual record (.45), progeny (.59), parents and grandparents (.22), relatives (.30). takes about 7 progeny to = acc of individual.

109
Q

effective progeny number (EPN)

A

total number of progeny adjusted for the number of herds. 200 calves in 1 herd, vs 75 cows over 3 herds. gets better sample of cows and management.

110
Q

EPDs can not be compared across breeds bc

A

different genetic bases, different genetic trends

111
Q

main factors affecting profitability

A

percent calf crop weaned, average weight of calves at weaning, annual cow costs, and calf price (producer has very little control over this)

112
Q

% calf crop

A

ultimate goal is 1 calf/cow/yr. % calf crop = # weaned / #cows in breeding herd x 100.

113
Q

weaning weight and profits

A

nearly always if you increase WW, you will increase profit.

114
Q

combine % calf crop and WW

A

% calf crop x WW = lb calf weaned (sold)/cow in breeding herd. best single measure of cow productivity.

115
Q

reproduction

A

single most important factor in beef production. very complex involoving, heifer management, nutrition, bull management, calving ease, cow condition, breed, herd health, weather, others. heritability in repro is low, repeatability is high.

116
Q

main reasons cows to not wean a calf

A

females not pregnany at end of breeding season (17.4%), perinatal calf deaths (6.4%), calf deaths birth to weaning (2.9%), fetal deaths during gestation (afetr confirmed pregnant 2.3%).

117
Q

Heifers must reach desired weight to be bred to calve at 2 yrs old.

A

Breed and weight are main factors determining when heifers reach puberty. Breed first at 14 mo to calve at 23 mo. general rule is heifers should reach 65% of anticipated mature weight by 14 mo. if supplemental feed is used to develop heifers, sort by size and group feed. Fed together = lower adg and breeding wt. fed separately = higher adg and breeding wt and higher % preg. ideally, select heifers with heavy actual ww. monensin will hasten puberty (due to enhanced ovarian response to gonadotropin stimulation rather than increased growth; affects hormone production more than wt. cattle grazing will also increase adg).

118
Q

why select heifers with heavy actual WW?

A

less weight gain weaning to breeding. reflects dam with good milk production. dam bred early in breeding season. higher % of heifers breed and then rebreed early in breeding season. overfeeding can decrease fertility and milk production. more profitable. most heifers need to gain 1-1.25 lb/day, do not exceed 1.5. But ideal situations seldom exists so need a large number of replacements and genetically superios animals are not always born early.

119
Q

breed heifers to calve early in calving season

A

heifers calving early are more likely to be pregnant when 2 and 3 yrs old. ideally, 2/3 of calves should be born during first 1/3 of calving season. importance of calving early in season on WW: cows calving late in season will calve late next season, more likely to be open following breeding season, and calves born last 21 days avg 70-90 lb lighter than 1st 21 days. save more heifers than needed as potential replacements (at weaning save 50% more than actually needed). cull ~15% every year. some suggest 45 day breeding season for heifers; preg check 45-60 days after bulls removed (if you want cows that calve early, start with heifers).

120
Q

keep heifers separate from mature cow herd (at least 60 days before calving)

A

heifers have 15-25 days longer postpartum intervals than mature cows (return to estrus cows: 35-50 days (not nursing ~21 days), heifers: 45-60 days). good nutrition shortens postpartum interbal (1st calf, still growing, lactating). social dominance of older cows. heifers should reach at least 85% of mature wt by 1st calving.

121
Q

nutrition, body condition, and rebreeding

A

in general, cows and heifers should be in weight gaining condition going into calving and continue gaining (or at least maintaining) weight through breeding season. 120 critical days: increase feed 10-15% last 30-45 days of gestation. check protein. after weaning is the lowest nutrient requirements. increase lactation ration by 50-60%, prob will need protein suppl.

122
Q

body condition scores (BCS)

A

9 point system. highly correlated with length or interval to 1st postpartum estrus. easy to use - minimum labor. use to adjust feeding levels. relationship of BCS at calving to number of days to estrus postpartum (cows showing heat vs body condition). min recommendations at calving: heifers 5.5, cows spring calving 5, cows fall calving 5.5. BCS = 5.5-6 is a good goal. can expect 90% of cows preg. needs to be bred 80 days postpartum.

123
Q

reseach results to aid management decisions

A

weight gain/loss before calving appears more important than gain/loss between calving and breeding. before calving, can make max use of forages to increase BCS. after calving need much more grain - economincs - keep annual cow costs. good prepartum body condition (5-6) will modulate impact of nutrition on rebreeding. effect of weight changes will be minimal. >5.5 BCS may pose no problem when weather or nutritional stresses are minimal; however these stresses are difficult to manage. hort term stresses will reduce conception rates.

124
Q

close observations at calving, esp heifers

A

25-45% of heifers will have some calving difficulties. breed important (exotics > British). Nutrition = moderate condition. too fat or thin = problems. limit feeding does not improve dystocia problems probably will increase postpartum interval. low BW bull. heifers month early.

125
Q

late afternoon feeding

A

fewer calves born at night. still need nighttime observation.

126
Q

select for proper BW to minimize dystocia

A

relationship of WW and YW to BW. cows given assistance at birth have longer postpartum intervals and pregnancy rates decreased ~15-20%. sire selection important, use EPDs for BW and calving ease and beware of exotic breeds. pelvic measurements - measure width and heighth of canal (BW EPD better). as BW gets heavier and pelvic measurements get lower, the more dystocia.

127
Q

bull management

A

BSE, fertility, serving capacity, management principles.

128
Q

BSE

A

breeding soundness evaluation. 3-4 mo ahead of time. physical soundness (feet and leg problems, sheath adhesions, penis (deviated, split, ruptered), palpation (scrotal and rectal). semen quality (morphology and motility). Libido (observe bulls carefully, not predicted by physical or semen test, conception rates related to libido, no reliable tests).

129
Q

fertility

A

~45 days for sperm cells to mature (total of 60 days from spermatogenesis to ejaculation). spermatogenesis affected by fever, heat stress (semen may be reduced for 8 wks after end of stress), extreme cold, over feeding, disease. careful with whole cottonseed due to gossypol. the ideal calving season is late jan and feb but you have to breed in may, so may be too hot for bull, breed in fall may be better.

130
Q

serving capacity

A

15 mo = 10-15 cows. 18 mo = 15-18. 2 yr = 20-25. mature = 25-35.

131
Q

some management principles for bulls

A

BSE before breeding season. quarantine newly purchased bulls. if pasture breeding, run bulls together before breeding season. young bulls need extra feed. nutritional requirements of working mature bull about same as cow in early lactation. dont overwork young bull (use only 46-60 days). young bulls may fall in love with a cow in estrus (over active, lose weight and body condition).

132
Q

use corssbred females

A

heterosis for fertility. heterosis increased lb claf weaned/cow exposed by 20%. 65-75% of this increase is due to uncreased fertility. 25-35% of this increase is due to increased growth rate of calf and increased milk from cow (not a lot of heterosis in milk). increased vigor in crossbred cows

133
Q

management after 7 days postpartum

A

only 2-3% of calf losses occur after 1st week. protect calves from weather. watch for infectious calf scours, secondary pneumonia.

134
Q

manage for return to estrus

A

suckling intensity lengthens postpartum interval. (suckling intensity = total length of time a cow is nursed per day, inhibits gonadotropic hormones). effects can be seen with: twins (even in cows fed to maintain the same weight and body condtition), crossbred calves (may be a factor when considering crossbreeding in a situation where nutrition for the cows is marginal), males > females (increase postpartum interval by 3-4 days). calf withdrawal schemes. estrus synchronization.

135
Q

calf withdrawal schemes

A

cows that lose a calf at birth return to estrus in 21 days. allowing calves to nurse only 60 min each day beginning around day 30 shortens ppi significantly, but this is labor intensive. simplest to remove calves from cows for 48 hours approx 10-14 days before breeding season (makes allowance for some cows that will have a short nonovulatory cycle). calf withdrawal will not work for thin cows. calf withdrawal has no effect on WW.

136
Q

estrus synchronization

A

does not cause cows to cycle, they must already be cycling. more uniform calf crop. increase WW of the herd..fewer calves born late.

Beef Production (2 decks)

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