lecture quiz 20: feedstuffs continued

Question 1

grinding: hammer mills

Answer 1

• hammer mills can be portable or stationary
• steel shaft w/ hammers that swing
• feed is battered
• screens set size → diff stages/size or prod type gets diff sizes (e.g. growers get larger particles)
• common for swine & poultry
• produces range of particle size → some too fine & becomes dust so gets lost → loss of feed = loss of profits

Question 2

grain processing

Answer 2

• main reason: ↑ digestibility
• organized into granules that are not easy to digest
• physical interrupts seed coat & ↓ particle size that ↑ SA exposed to digestive enzymes
• thermal (steam or moist heat) → starch swells & gelatinizes
  
  • gelatinization = starch gel
  • gelatinized = more digestible (e.g. bread)

Question 3

dry rolling: roller mills

Answer 3

• grains pass between 2 rollers that flatten the grain
• can adjust the closeness of the rollers to adjust thickness
• benefits over grinding: less fine particles & more uniform particle size compared to hammer milling
• no change in digestibility or energy
• mainly for horses & ruminants

Question 4

steam rolling

Answer 4

• steam 1-8 mins
• softens but does not modify starch (exposure time is not long enough)
• less loss of dust b/c using moisture
• no change in digestibility
• does not gelatinize
• not much diff than dry rolled
• mainly used for ruminants & horses

Question 5

steam flaking

Answer 5

• steam for 15-30 mins then roll to a flake
• gelatinizes starch granules
• improves digestibility
• mainly used for ruminants & horses

Question 6

processing for pets

Answer 6

• cooking uses extrusion process that uses high level of moisture, heat, & pressure to create kibble (pellets)
• dogs & cats cannot digest without cooking (like humans)

Question 7

effect of processing on corn energy values

Answer 7

• processing increases digestibility ∴ increases energy values
• TDN or NE

Question 8

protein feedstuffs

Answer 8

• high in protein = >20% CP
• also high in energy (>70% TDN) but main reason in feed is for high CP
• can be categorized into:
  
  1. plant-based protein feedstuffs (e.g. oilseed meals = primary form of plant-based protein for livestock)
  2. animal-based protein feedstuffs → highest quality protein
  3. non-protein N (NPN) sources for ruminants (urea)

Question 9

plant-based protein feedstuffs

Answer 9

• as oil is removed, [protein] is increased
• oilseed meals = residue from extraction of oil from oilseeds
• e.g. soybean, canola, sunflower seeds
• different methods of extraction:
  
  1. mechanical: cook seed to soften then press through dies to squeeze oil out
  2. solvent extraction: solubilize the oils in seed w/ organic solvent (hexane) then heat to evaporate solvent (more efficient)

Question 10

soybean meal

Answer 10

• most widely used plant protein feedstuffs
• highest protein quality of any plant protein source (not animal)
• CP 44-48%
• processing soybeans for oil & meal:
  
  1. hull (remove hulls)
  2. crack
  3. extract w/ hexane (remove oil)
  4. residue in meal is toasted to inactivate trypsin inhibitors that reduce digestibility of proteins
  5. hulls may be added back (↑ CF)
• soybean hulls commonly used for ruminants → high CF but highly digestible
• can be used in both ruminant & non-ruminant diets including pet food & aquaculture
• major protein source for poultry & pigs

Question 11

trypsin inhibitors

Answer 11

• all beans have anti-nutrients
• found in soybean meal
• reduce protein digestibility in non-ruminants (ruminants can digest in rumen)
• inactivated/destroyed by heat (toasting)

Question 12

canola meal

Answer 12

• cool climate crop (canada, north dakota, Minnesota)
• small seeds (similar to milo)
• hard coat → requires grinding
• byproduct of canola oil industry
• mainly used as ruminant feeds but can feed to non-ruminants & aquaculture
• usually sold in bulk form as mash or pellets
• has good source of protein, but has CF

Question 13

cottonseed meal

Answer 13

• byproduct of cotton, cottonseed oil
• oil extraction occurs by solvent & mechanical methods
• high energy & high protein & CF
• excellent source of protein for ruminants but only limited use in non-ruminants due to gossypol toxicity

Question 14

gossypol toxicity

Answer 14

• occurs in non-ruminants from cottonseed meal
• symptoms similar to pneumonia:
  
  1. respiratory distress
  2. coughing
  3. loss of appetite
  4. weakness
  5. male infertility (in humans) → research in using as contraceptive for males
• polyphenol
• increased erythrocyte fragility
• stimulates eryptosis (apoptosis of erythrocytes)
• binds to iron & free amino group of proteins & peptides
• interferes w/ enzymatic activity in mitochondrial e⁻ transport chain & oxidative phosphorylation