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Animal Nutrition AnSc 315 > Nutrients and Their Analysis > Flashcards

Nutrients and Their Analysis Flashcards

1
Q

what are the reasons for conducting feed analysis

A
  • diet formulation to provide balanced diets
  • to provide analysis for use in estimating available nutrients, energy (TDN, net energy)
  • to provide information to solve a production problem that may be feed related
  • to place a market value on a feed
  • to verify commercial guarantee
  • legal court cases
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2
Q

what are the main nutrient components of feed

A
  • water or moisture
  • dry matter (DM)
  • water % + DM% = 100
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3
Q

what are the 2 ways nutrient composition of feeds is expressed

A
  • as is basis or wet basis = moisture included in calculations of % nutrients
  • DM or moisture free basis - moisture is excluded
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4
Q

whats important for feed sampling

A
  • representative sampling from several locations
  • minimize possibility of alterations in feed composition during storage (sealed containers, freeze sample)
  • core sampling
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5
Q

what should you do for feed sampling

A
  • usually collect more material that is needed for analysis
  • grind (if possible) to allow thorough mixing of sampling
  • preserve if needed (fridge or freezer)
  • record sampling details (sample ID/label, date, source, location, condition, operator, take pictures)
  • send at least two samples for analysis, take average
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6
Q

what is the most commonn analysis of feeds

A
  • proximate analysis
  • developed >100 years ago at the weende experimental station in germany
  • series of analytical procedures that partitions the feed into 6 fractions
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7
Q

what is taken in proximate fractions

A
  • moisture (water) or DM
  • ash (minerals)
  • crude protein
  • ether extract or crude fat (lipid)
  • crude fibre (less digestible carbs)
  • nitrogen-free extract ( more digestible carb)
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8
Q

why is moisture or DM analysis important

A
  • moisture can vary in moisture content (10% cereal grains vs 65% in barely silage)
  • contributes to water requirement of animal ( drinking water is a major source)
  • high moisture can have negative effects
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9
Q

what are some negative effects of high moisture

A
  • can reduce feed (DM) intake
  • reduces proportion of other nutrients in feed
  • reduces storage life of feed
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10
Q

steps in dry matter determination

A
  1. weigh empty container
  2. place test feed in container, weigh feed + container
  3. subtract weight of container from total weight for test feed weight before drying
  4. place in drying oven (either 105-135% for 2 hours or 55% for 48 hours
  5. weigh, record weight of container + test feed immediately after drying
  6. subtract weight of container from total weight fo test weight after drying
  7. divide the weight of the dry test feed by weight of wet feed
  8. multiply by 100 to get DM %
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11
Q

what are the different methods of drying

A
  • oven drying = forced air oven, korster tester, microwave (loss of volatile materials )
  • moisture meter
  • freeze drying
  • near - infrared reflectance spectroscopy (NIRS)
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12
Q

what is ash determination

A
  • ash content = mineral content
  • only total amount of minerals is measured = individual mineral content unknown
  • useful indicator of diet composition = confirm addition of mineral premix to a mixed diet
  • all combustable material (OM) in test feed is burned off in muffle furnace heated to 500-600 leaving inorganic matter (ash) which contians these minerals
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13
Q

how do you determine ash

A
  1. weigh out a small quantity of test feed into an ashing crucible
  2. ash in a muffle furnace (500-600) for 5 hours
  3. weigh the residue
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14
Q

what are alternate methods of ashing

A
  • minerals such as iodine and selenium are volatile at 500-600C (could underestimate mineral content)
  • wet-ashing procedure ( OM destroyed by boiling in concentrated perchloric acid (hazardous)
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15
Q

how do you measure crude protein

A
  1. weigh out 0.5-5 g of test feed
  2. digest by boiling in concentrated sulfuric acid (1 Hr)
    - converts all N to ammonium sulphate
  3. cool, dilute with water, add concentrated NaOH (converts ammonia (NH3) )
  4. distill NH3 into a known quantity of boric acid (traps NH3)
  5. titrate distillate with HcL drop-wise to determine N content
  6. calculate the amount of crude protein in test feed by multiplying the amount of total N by 6.25
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16
Q

what is the taco-kjeldahl apparatus

A
  • digestion + distillation components in one space-saving apparatus ; blower to exhaust fumes
  • always contains 16% proteins
17
Q

what are the limitations of kjeldahl CP determination

A
  • the assumption that all protein contains 16% N (use 6.25 with mixed feeds (diets))
  • use appropriate conversion factor with individual feed ingredients
  • assumption that all N comes from protein (non protein N sources, ruminants Vs non-ruminants)
18
Q

what animal can utilize NPN

A
  • ruminants
  • urea as non-protein nitrogen (NPN) contains 45% N, which is equivalent to 281% CP ( bacteria in rumen can use NPN to build microbial protein - provides amoni acids at S I)
  • urea toxicity limits feeding - mortality
  • limit to 2% of diet
  • urea unpalatable, mix with malasses
19
Q

what is crude fat

A
  • either extract
  • or either soluable material
20
Q

how do you determine ether extract

A
  1. weigh out 1-5 g of test feed
  2. remove water by oven drying
  3. extract test feed with diethyl ether in a soxhlet extractor for several hours
  4. evaporate the ether from the extract and weigh the remainder (residue = ether extract/ crude fat)
  5. %EE = wt of residue/ wt of original sample X 100
21
Q

what are compounds found in ether extracts

A
  • tryglycerides (energy = major source)
  • free fatty acids ( energy = major source)
  • cholesterol (making steroids and building block for vitamin D)
  • fat-soluable vitamins
  • resins, waxes ( do not contribute anything to the animal, they are not fat)
22
Q

what are problems with either extract

A
  • EE fraction assumed to have high E content
  • if EE fraction contains a high % of waxes, resins, then the energy in feed can be over estimated
23
Q

what consists in crude fibre

A
  • feed components of low digestibility (cellulose, hemicellulose and lignin)
24
Q

how do you determine crude fibre

A
  1. weigh 1-5g of ether-extracted test feed
  2. boil in dilute H2SO4 for 30 minutes; filter; then boil in dilute NaOH for 30 minutes; re filter
  3. dry residue, weigh (whats left = crude fibre)
  4. % CF = weight of residue/ weight of feed sample X100
25
Q

what are the issues with crude fibre

A
  • not a chemically defined fraction
  • some cellulose, hemicellulose and lignin extracted which then ends up in the nitrogen free extract (NFE)
  • not highly repeatable
  • not used anymore
26
Q

what is nitrogen free extract

A
  • FE designed to contain the digestible carbohydrate fraction (starch, sugars)
  • no chemical analysis for NFE
  • all erroros associated with prior analysis; incomplete extraction of crude fibre
  • NFE = 100- (%CP + %EE + %CF + %ASH + %H2O)
27
Q

what are some advantages of proximate analysis

A
  • requires relatively inexpensive equipment
  • provides a good general evaluation of feedstuffs
  • TDN energy system is based on proximate analysis
  • most of the current nutritional data is based on proximate analysis
28
Q

what are soe disadvantages of proximate analysis

A
  • does not define individual nutrients
  • some errors in basic assumption ( assume all nitrogen is 16%)
  • time consuming - can be up to two days
  • gives no indication of digestibility
  • partitions carbs poorly (i e digestibile Vs indigestible )
29
Q

what are alternates of crude fibre

A
  • detergent extraction system developed by Van Soest at cronell university
  • used primarily for forages
  • partitions the fibre component into soluable and insoluable carbs
    (neutral detergent NDF and acid detergent (ADF) fibre )
30
Q

what is in NDF

A
  • hemicellulose
  • cellulose
  • lignin
31
Q

what is ADF

A
  • lignin
  • cellulose

Animal Nutrition AnSc 315 (9 decks)

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