ration evaluation Flashcards

1
Q

what is the important input cost in animal production systems

A

feed

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2
Q

what percent of the cost of production is feed

A

50-70%

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3
Q

what are the 3 components of animal production and feed

A
  • feed for animal maintenance (fixed)
  • feed for production (varies)
  • feed for replacement animal (fixed)
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4
Q

what is “feed for animal maintenance”

A
  • body size and environmental conditions
  • ability to perform “everyday” activities
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5
Q

what is “feed for production”

A
  • growth
  • milk production
  • reproduction
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6
Q

what is “feed for replacement animal”

A
  • animals must be raised to replace current production animals
  • heifers, steers, gilts, chicks
  • goal is max efficiency at entry level (24m vs 48m to raise replacement)
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7
Q

what do long feed out periods carry a lot of

A

“maintenance cost”

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8
Q

why is higher production efficient

A
  • every farm has a goal
  • some farms better than others
  • low yielding herds at risk of leaving industry
  • evolution to capture efficiency
  • evolution of nutrition
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9
Q

what is fixed relative to

A

production

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10
Q

what are the benefits of energy budget

A
  • economic
  • environment
  • resource use
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11
Q

what is energy budget directly influenced by

A

management factors

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12
Q

what do larger herds tend to have

A

better/dedicated managers and consultants

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13
Q

what is the amount of certaintly of iron and calcium

A

varies widely - “OK” window is larger

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14
Q

what is the amount of certaintly of energy/protein

A

tighter “OK” window

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15
Q

what are the two ways nutrient requirement measurements are presented

A
  1. amount of nutrient
  2. densisty basis
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16
Q

what is the nutrient density requirement equation

A

nutrient amount / total DM intake of the animal

17
Q

what is the dry matter content of the corn silage?

100lbs corn silage (AF); 35lbs corn silage (DM)

A

35/100 = 35% DM

18
Q

what is the moisture content of the corn silage?

100lbs corn silage (AF); 35lbs corn silage (DM)

A

100-35 = 65% water (moisture)

19
Q

a horse consumes 20lbs (AF) of timothy hay that is 90% DM. What is the dry matter intake of hay for the horse?

A

20lbs of hay X 0.90 (%DM) = 18lbs of dry matter

20
Q

haylage DM decreases to 30%. how much haylage should the producer now feed?

DMlbs - 6.75

A

6.75 lbs (DM) haylayge / 0.30 (DM%) = 22.5 lbs (AF) of haylage

21
Q

what is the equation of dry matter to as fed

A

(DM lbs ) / (%DM) = as fed lbs

22
Q

what is the equation of as fed to dry matter

A

(AF lbs) X (%DM) = dry matter lbs

23
Q

nutrient densities

A
  • measures on dry matter and as fed basis
  • most laboratory analysis contain both

DM will be more dense

24
Q

CP of 20%; DM of 40%. what is the CP% of AF?

A

nutrient density DM X DM% = nutrient density AF

20% DM CP X 40% DM% = 8% AF CP

25
Q

CP of 20% DM; DM% of 40%; cow consumes 30 lbs/day (AF). How much CP does she get from haylage?

A

method 1:
* 30lbs hay X 40% = 12lbs DM of hay
* 12 lbs of DM hay X 20% = 2.4 lbs of protein

method 2:
* 20% DM CP X 40% DM = 8% AF CP in hay
* 8% X 30 lbs = 2.4lbs of protein

26
Q

you want to feed 2lbs of protein to a cow using soybean meal which has a 48% AF CP level. How much soybean meal should u feed?

A

2lbs of protein / 48% (CP%, AF) = 4.16 lbs SBM (AF)

27
Q

know how to do person square example - solving a mix - create a mix with 16% CP (AF) with shelled corn (9% AF CP) and soybean meal (48% AF CP)

A
  • 18% SBM
  • 82% Corn
28
Q

how do you solve for two nutrients

A
  • need at least two feed ingredients
29
Q

how to solve for 3 nutrients

A
  • 3 feeds
  • 3 equations
  • find the point where all 3 lines intersect
  • sol. might not exist
30
Q

what does linear programming allow us to do

A

formulate rations with “nutrient winows” rather than absolute amounts

31
Q

what is the objective of linear programming

A

identify ingredients/ amounts that minimize cost

32
Q

what are some key concepts in linear programming

A
  • meet/exceed energy requirements
  • meet/exceed protein requirements
  • “fit” the dry matter intake capacity of the described animal
  • be within a range of nutrient levels
33
Q

what are the steps in linear programming

A
  • describe objective
  • identify decision variables
  • find optimal solution
  • (+/-) evaluate sensitivity analysis
34
Q

what variables do you have control over

A
  • amount of corn silage fed/day
  • amount of soybean meal fed/day
35
Q

what does LP tell us

A

the optimal amount to feed of each ingredient

36
Q

what are RH values or constraints

A

things you cannot change (DM, mcals, protein, ADF)

37
Q

what are matrix coefficients

A

variables (type of feeds and amounts)