Nutrient Analysis

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Nutrient Analysis

• Animals require certain chemicals from their diet
  in order to function
• Other food chemicals may be negative
• Nutritionists must be able to measure these
  chemicals to know feeds value
• Enables ecologists to condense the huge array of
  foods an animal may eat into a manageable set of
  chemicals important to the animal

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Nutrient Analysis

• Fig. 1 from page 308 of Wildlife Techniques Manual

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Nutrient Analysis

• Water
• Important to measure because
• Preformed water
• Water may dilute other nutrients (e.g. cactus)
• Express food content on dry matter basis
• Determine moisture by drying at 100 C for 24 hrs
• Samples may contain volatile chemicals
• Can dry at a lower temperature (e.g. 60 C)
• Freeze dry sample (lyophilize)

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Nutrient Analysis

• Next division is inorganic vs. organic
• Minerals are inorganic component
• Important in animals metabolism
• May have negative consequences
• Silica may lower digestion of fiber. Found in
  grasses and up to 30 of weight of Equisetum
• Minerals quantified by atomic absorption and
  colorimetric procedures
• Ash is sum of all inorganic material
• Burn in muffle furnace at 500-600 C for 2-4 hrs.
  Weigh sample before and after

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Nutrient Analysis

• Organic compounds
• Carbohydrates (CHOs)- Sugars and polymers
• Non-structural Energy storage for plants
• Glucose, fructose, sucrose
• Starch, a polymer of glucose
• Structural -
• Cellulose Glucose polymer resistant to
  digestion by vertebrate enzymes
• Hemicellulose A diverse group of polymers of
  other sugar compounds. Hydrolyzed by acids and
  bases and thus partially digested by vertebrates.
• Pectin Soluble fiber in fruit and dicots.

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Nutrient Analysis

• Lipids High energy molecules
• Fatty acids and triglycerides used for energy
• Waxes, volatile oils also lipids but not used by
  animals for energy
• Protein Discussed in detail earlier
• Protective or defensive compounds
• Plant chemicals that reduce herbivory
• Dilute nutrients
• Reduce digestibility
• Affect animals metabolism (toxicity)

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Plant Compounds

• Lignin large, aromatic, nonsaccharide polymer
  that makes plant cell wall rigid
• Not digestible by vertebrate or symbiotic
  microbes. Common in woody plants gt some dicots gt
  grasses
• Reduces digestion of cellulose
• Cutin and subrin aromatic polymers resistant to
  digestion.
• Important in wound healing and as a physical
  barrier. In woody plants, absent from grasses
• Reduce digestion of cellulose.

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Nutrient Analysis

• Proximate Analysis Basis of much of our forage
  analysis. Has been used for over a century.

Insert Figure of Proximate Analysis
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Nutrient Analysis

• Ether Extract Crude fat
• Soak sample in ether to dissolve lipids
• Use apparatus that continually washes sample with
  ether
• Weigh sample before and after ether extract
• Ether also extracts pigments, waxes, volatile
  oils, resins, sterols, etc Thus term crude fat
• Crude Fiber Meant to be the undigested portion
  of the food.
• Boil 30 min in dilute H2SO4 and 30 min in dilute
  NaOH. Weigh before and after.

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Nutrient Analysis

• Crude Protein Measure nitrogen. Variety of
  techniques. Kjeldahl is common
• Boil in concentrated sulfuric acid with catalyst
• Add NaOH to release NH3, which is captured in a
  weak acid
• Titrate acid to determine N in sample
• Nitrogen Free Extract 100 Fat Protein
  Fiber Ash
• Suppose to be most digestible portion of feed
• Will reflect mistakes from all other analyses

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Nutrient Analysis

• Ether extract, Kjeldahl, and ash widely used
• Crude fiber has problems
• Hemicellulose and lignin soluble in acid or
  alkali thus counted in NFE fraction.
• In 1960s, Detergent Fiber Analysis developed (Van
  Soest analysis)
• Plant can be divided into
• cell contents, highly digestible
• cell wall, requires microbes to digest

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Nutrient Analysis

• Insert Figure showing cell contents and cell wall

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Nutrient AnalysisDetergent FiberAnalysis

• Insert Figure showing detergent fiber analysis

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Nutrient Analysis

• Insert Figure comparing results of crude and
  detergent fiber

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Nutrient Analysis

• Total dietary fiber developed to analyze human
  foods, i.e. foods eaten by monogastric species.
• Fats are removed by treatment with ether
• Enzymes remove protein and starch
• Ethanol used to precipitate soluble fiber
• Sample filtered and residue is TDF

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TDF vs. Digestibility
Dry matter metabolizability vs. TDF for
white-winged doves
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Nutrient Analysis
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Nutrient Analysis