Lecture 10- Poultry and fish Flashcards
What are the characteristics of Birds that impact their nutrition
- Rapid growth
- Precociousness for commercially important birds; opposite is altricial • precocial = early development, born eyes open and leave nest within 2 days
- altricial = hatched with eyes closed – cannot leave nest, fed by parents etc.
- Feathering • Biped
- Oviparity
What is the digestive anatomy of a fowl like?
-cloaka= one hole for urine and faeces
• Crop
• stores and moistens food.
• Length of time food spends in the crop depends on its nature (grains spend longer).
• Crop fullness partially regulates feeding activity.
• Gizzard (muscular stomach)
• Teeth for birds
• Thick powerful muscle used to grind food
• ‘grit’ in feed important
• Development depends on feed consumed
• Cloaca
• Common cavity for intestinal, urinary and genital tracts open.
What are the nutrients requirements of birds?
-The first requirement for a poultry diet is protein (AA) as they quickly! need it for muscle etc.
-Amino acids
=10 of the 22 amino acids which occur in feedstuffs are absolutely essential
in the diet of the bird
• Methionine can be converted to cystine
• Phenylalanine can be converted to tyrosine
• Glycine and serine are interconvertable
-Diet must be balanced to include adequate levels of all amino acids
What are poultry feeding systems?
1-Whole grain method (must get groot to break it up)
2-Grain & mash
3-All mash: fed at first 8W
4-Wet mash feeding (more palatable) 5-Pellets
- With grain feed must use insoluble grit
-Also fresh green feed is fed to poultry
What is the importance of AAs for poultry?
•Amino acids -A deficiency of one amino acid causes reduced utilization of the others -Amino acid inadequacy causes • poor growth • lower feed conversion • reduced egg production • reduced egg size • increased carcass fat (don't want too much fat) •Amino acids -Nonessential amino acids comprise about 50% of carcass amino acids. • Made quite effectively in the body -Excess nitrogen excreted as uric acid • Conserves water
What are interactions and AA requirements?
- The requirement for cystine can be met by methionine (plus serine)
- Methyl group donor
- Catabolism of methionine → cystine results in sulfur → sulfate which can be used in metabolism
- Methionine can also → choline which is used in phospholipds and important for membrane structures
- Methionine in excess can be toxic!
- Phenylalanine and tyrosine
- Tyrosine formed when phenylalanine is catabolised
- Thus can be used to meet tyrosine needs (equimolar)
- Glycineandserine
- Glycine non-essential BUT the synthesis rate does not support the rapid growth of fowl and thus serine → glycine (equimolar)
What are AA antagonisms?
-need a balance!
- Antagonisms occur when an interaction causes the requirement of one AA (not always the first limiting AA) is increased by adding a structurally similar AA to the diet
- Deficiencies of one EAA can be exaggerated by adding purified AA so the extent of the difference between 1st and 2nd limiting AA’s is increased
- i.e. adding one AA only when two are deficient
- Impairs weight gain
- The whole imbalance needs to be corrected
- Antagonisms can occur when one AA has a similar side chain to another → competition
- Leucine – isoleucine – valine
- Corn + corn gluten meal → high leucine & low isoleucine • Arginine – lysine
- Excess lysine increases the requirement for arginine • Theronine – tryptophan
What do you have to manage in terms of energy-protein interrelationships?
-need enough energy otherwise protein not useful
•Energy-protein interrelationships
ME is the measure of energy routinely employed in poultry nutrition
Birds have specific energy requirements depending on their body size,
physiological state, stage of production and environmental temperatures
• Energy drives requirements for other nutrients
• Poultry eat to satisfy energy so requirements of other nutrients must be met
Important to balance protein & energy to produce an economic diet
What are the water, fatty acid and carbohydrate requirements of poultry?
-Water:
Drink ~ 2x more water than volume of feed consumed
-Fatty acids:
Linoleic acid is only essential fatty acid
-Carbohydrates_
Main sources of ME
-Starch with small amounts of cellulose, hemicellulose and other fiber constituents
-Sucrose is readily digested and can be used for energy
-Lactose is poorly tolerated due to low lactase activity
What are the vitamin requirements for poultry?
- Vitamins_
- All, except vitamin C, are required
- Vitamin C may improve growth and production under conditions of heat stress
- Niacin can be synthesized from AA’s (tryptophan) but conversion rate is poor
What are mineral requirements for poultry?
-Minerals
-Deficiencies lead to impaired performance and a variety of specific
symptoms
• Thin eggshells (Ca)
• Poor calcification of bone (Ca and P)
• Perosis (Mg)
• Exudative diathesis (Se)
P from plant sources is poorly available as it is bound to phytate
• 30% of plant P is bioavailable
What are the requirements of calcium and phosphorus for poultry?
- The recommended ratio P:Ca in diet of poultry is 1:1.2 (range 1:1 to 1:1.5) For laying hen 1:4 ( Ca important for bone & shell formation)
- increase Ca in diet => decrease utilization of Mg, Mn & Zn.
- Inorganic P have a higher availability than organic P
- All P from animal origin & 40% from plant origin (wheat bran & rice bran) is available.
• Excess dietary calcium can interfere with availability of other minerals & become unpalatable
• Zinc, manganese, phosphorus & magnesium
What are the requirements of xantophylls for poultry?
- Carotenoid pigments responsible for yellow/orange colour of yolks & fat
- Also skin, feet & beak colouring
- Presence of hydroxyl groups
- Vitamin A & antioxidant activity
- E.g. Lutein in forages such as lucrne (alfalfa) • Zeaxanthin in in corn
- Important for poultry nutrition
What are the consideration of diet for chickens?
- Grow for market specifications
- Fat depths / colours etc
- Egg yolks bright yellow
- Gossypol → green yolk = undesirable
- Balance protein for desired egg size • Less protein = smaller eggs
- Inadequate vitamin D → weak shells
What are the typical rations for chickens?
-have high energy source like wheat, medium energy source like oats, then vegetable protein and often fish and meat products, fats and oils and alfa alfa meal and Ca and P
-• Additional fat (isoenergetic to carbohydrate) can improve production
• Particularly in adolescence
• Synthesis of fat from carbs (primarily in the liver) is less efficient than providing fat in feeds
• Dietary fat is important for yolk lipid content & improves egg weight
-amount of feed per gram of meat has decreased, has gotten more efficient
