Selection of beef cattle Flashcards

1
Q

what is the most important thing in commercial beef cattle operations

A

reproduction or the creation of new wealth

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2
Q

what does beef cattle having low management emphasize

A

genetic potential

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3
Q

what are some reproductive traits for females

A

-conception rate (0-.1)
-calving interval (0-.1)
-fetal survival to weaning (depends of mothering ability and milk quality)
-calving ease (pelvic measurements
-twinning

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4
Q

what are some correlations with reproduction

A

-back fat was negatively correlated to super ovulation response
-r=-.66, P=.001(signif)

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5
Q

what are some reproductive traits for males

A

-sperm count
-sperm morphology
-scrotal cirumfrence

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6
Q

what does scrotal circumference positively correlate with

A

-sperm count
-age of puberty
-fertility in daughters
h2=.4-.6
>=32cm

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7
Q

growth traits

A

-birth weight (.3-.4)
-wean weight (.3-.35)
-postwean gain (.5-.55)

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8
Q

genetic correlations of growth

A

-weaning wt:postwean gain .46
-weaning wt:carcass grade .52

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9
Q

what are some factors for adjusted weights

A

-age
-sex
-age of dam
-twins

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10
Q

adjusted weights: age

A

-weaning wt. adjusted to 205 days
-(150-250 day target)

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11
Q

adjusted weight: sex

A

heifer calf(1.1)=steer calf(1.05)=bull calf(1.0)

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12
Q

adjusted weight: dams age

A

2-+15%
3-+10%
4-+5%
5-10-0%
greater then 11-+5

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13
Q

adjusted weight: twins

A

twin is 75% of singleton

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14
Q

feedlot gain

A

-h2=.50-.55
-feed/gain efficiency:
-6:1 6lbs to get 1lb
-6 is good in lot
-6.5 more typical
-feed conversion: 1lb gained while fed 5lbs 1/5 or .2

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15
Q

carcass quality heritability

A

-slaughter grade .4-.45
-rib eye area .55-.6
-tenderness .5-.6
-marbling .4-.45

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16
Q

when does tenderness of a carcass matter

A

farm gate

17
Q

camera grading system for rib eye

A

-check the 12-13 rib
-in the thinnest area
-take several measurements
-also look at yellow im fat

18
Q

what is marbling highly correlated with

A

-to palatability (juiceness, flavour)
-grade fat (which is an average of 3 back fat measurements)

19
Q

what are some meat quality tests

A

-marbling test
-tenderness test

20
Q

why is longevity an important trait in beef cows

A

-heifers have more problems calving but “olds” abort more
-overall production costs are lower if cows kept longer

21
Q

why is there so many breeds and species of beef cows

A

they have a wide variety of different environments
-heat tolerence
-pasture conditions
-parasite resistance

22
Q

mating systems of beef cattle

A

-inbreeding (reducing fertility, calf survival)
-crossbreeding (norm of commercial, using complementation and heterosis, increased fertility and weight)

23
Q

purebred cattle

A

-main product:
-bulls
-semen
-some embryos

24
Q

selection systems

A

-individual selection:
typical in commercial industry for cows and bulls (use of EPDs increasing)
-independent culling:
most common: growth and fertility