Physiology of poultry digestion. Feeding of broiler chicken Flashcards
What % of total cost is the feeding of poultry?
75-80%
- therefore its very important to have balanced and effective diet
- nutrition nfluences the composition of animal products
- food safety
Length of GIT comparing to body length. Why is it important?
1 : 5-6 for poultry
Comparing to 1 : 15 in swine —> much more time for digestion
=>
- poultry has short GIT —> short passage time —> nutrients should be digested really fast
- poultry should be fed with very valuable, good digestible feed (grains, legumes seeds, extracted meals)
What is important about the beak?
Chickens and turkeys are seedeaters =>
- to influence feed intake according to to nutritional aim (they will prefer seed-like feed and will eat more)
- so to reduce feed intake we don’t necessary give less food but give it in a form that animals less prefer
- Ducks: adapted to water
- beak is bad for picking up mash (big waste of feeds)
- pellets will have much less waste - Geese: adapted to grazing
How different physical form of feeds influence voluntary feed intake?
- mash: really small particle, almost powder-like. Not preferred by poultry
- pellet: size is according to species. They love it ^-^
- crumble: technically pellets but with smaller particle sizes. Something in between. For young chicks for example (they are small)
- also more compressed feeds have more nutrients in smaller volume —> increasing DMI
How different physical form of feeds influence voluntary feed intake?
- mash: really small particle, almost powder-like. Not preferred by chicken and turkeys (seedeaters)
- pellet: size is according to species. They love it ^-^
- crumble: technically pellets but with smaller particle sizes. Something in between. For young chicks for example (they are small)
What’s important about crop?
- developed for storage of feeds
- in young birds (1st week of age) crop is very small —> can’t store feed —> fed without limits
- geese and ducks dont have crops but oesophagus is very flexible -> not a problem
What’s important about small intestine
- really small and tight ->
- time for digestion is short
- volume is small
- NSP (non-starch polysaccharides) in grains won’t be able to be digested (starch will be able to be digested by amylase) => some energy of feeds will be lost without utilisation but more important is antinutrient effect of NSP:
- NSP have high viscosity -> in the gut will bind fluids together with some water-soluble nutrients -> and because NSP are indigestible they will be excreted TOGETHER WITH OTHER NUTRIENTS!!!
- in tight intestines this effect is more severe
What’s important about caeca?
- in birds caeca is underdeveloped (small comparing to whole GIT) —> fiber requirement/tolerance of birds is very low
- usually 3-4% fiber is present in diet for different poultry species (except geese)
What breeds are used for production of broiler chicken and egg-laying chicken (hybrid) ?
Additional info not for example
Meat:
- male line: white Cornish (heavy breed: 3,5 - 4 kg)
- female line: Plymouth Rock (medium breed)
Eggs:
- White Leghorn (light breed: < 2kg) x Rhode Island/New Hampshire (medium breeds)
- only leghorns also van be used but different lines
Basic data for broiler chicks !!! (BW at hatching, length of fattening, BW at slaughtering)
- BW at hatching: 40 g (correlates with mortality rate)
- length of fattening: 38-40 d (< 1000 hours) -> slaughtering age is between 5 and 6 weeks
- the younger chicken is at slaughter -> higher % of water in meat (lower quality of the meat)
- slaughter weight: ~2,7 kg (almost x70 than at hatching)
Feed efficiency and dressing % for broiler chicken
- feed efficiency:1,6kg/kg 1,6 kg of feeds for 1 kg of BWG (lower number -> better the efficiency !) (in turkey: 2,5; swine: 3-3,5)
- dressing % = weight of carcass (what we buy in shop) comparing to BW during life
- dressing % > 70% (in turkeys ~80%)
Determination of the age of slaughter
- first in chicks life mainly muscle (protein) is built up
- later less protein and more fat
- problem: we don’t want any fat —> this influences when we decide when to slaughter the bird
With age:
- loss of growth capacity (wont grow as intensively as in the beginning of life)
- increased fat inbuilding (and it requires much more energy. Moreover fat is stored in the stomach -> will be wasted
- just becomes waste of money to keep them alive
How to express nutrient requirements of the birds?
(??)
We give the necessary nutrient contents of their diets (???)
Multiple stage diet — ?
Body composition is constantly changing —> theoretically could create new diet every day
But one diet won’t be enough for whole period => 3 different diets = multiple stage diets
Broilers. Composition of multiple stage diet: protein, energy
- Starter: 0-10 days
- Grower: 11-24 days
- Finisher: 25 slaughter
- change is not abrupt! In 2-3 days usually
- CP requirement with age is decreasing => will be decreasing tendency (S: 23; G: 21,5; F: 19,5% of CP)
- energy demand has increasing with age (S:12,6; G: 13; F: 13,4 MJ/kg) Why? —> energy required for maintenance is increasing (correlating with BW); also fat inbuilding requires more energy; also to maintain good feed efficiency feed energy level should be high (to reduce the feed intake)
- approx 60-70% are cereals (high energy but poor in CP) + 30-40% protein sources (legumes/extracted meals)
- but grower diet’s energy demand in higher than energy content of cereal grains —> adding energy source is needed (plant oils/oil seeds)
What is the difference between soybean and full-fat soybean?
Full-fat soy bean was het treated to inactivate antinutritive factor of soy (tripsin inhibitors)
Composition of multiple stage diet: AAs
- ~60-70% do diet are cereal grain that are extremely poor in lysine, methionine and cysteine (3-5 g/kg) (several times less than needed) —> AAs supplementation is very important
- AAs supplementation are used to cover AAs demand + to make optimal ratio of AAs + decrease CP needed + spare energy (splitting non-utilasable AAs into pieces and converting N into uric acid requires energy)
lysine: decrease - ratio of AAs in the blood influences what % of AAs will be incorporated into body proteins
Why is it good to decrease demand in CP by adding AAs supplementation (with optimum ratio)?
Because crude protein also contains non-protein nitrogen —> excretion —> environmental pollution (uric acid)
Composition of multiple stage diet. Linoleic acid. Ca and Na
- linoleic acid is essential (omega 6)
- if there is not enough linoleic acid —> BWG drops
- F: 1,3; G: 1,2, F: 1 %
- big calcium demand !
- cereals are **extremely poor in Ca < 1 g/kg
- calcium supplementation !!!
- ~0,3% of NaCl supplementation is needed
Phosphorus <-> non phytin phosphorus
- non-phytin phosphorus = available phosphor because not all the phosphorus can be utilised
- cereals are rich in P (10x more than Ca) but not all that P is available for the birds
- when we check P content of cereal grain, ~ half of P is bound to phytic acid —> animals can’t utilise this bound P because enzyme is needed that could split this bond (phytase); but animals don’t produce this enzyme —> half of total P will be excreted —> non-phytin P is used to evaluate P content
Crude fibre requirement of poultry
- very low requirement: 2-4%
- because caeca is underdeveloped !
- if CF > optimum —> significant decrease of digestion of other nutrients
Is homogeneity of feeds important ?
YES ! (In this regard pellets are better)
Protein : energy ratio
Important to consider that if energy level of diet is increased —> DMI will decrease —> we should balance all nutrients, most important: protein !
Practical side of nutrition of broilers. Housing, feeding methods, water
- housing: no connection to environment, artificial light, heating, feeding, drinking; kept on deep litter
- feeding ad libitum, automatic feeders
- tap water: 2-2,5 litres of water per kilo of DM
- when feed intake drops, first thing to check: water supply !!
- mixed sex or sex dependent rearing (sexual dimorphism is not really noticeable, mainly BW: males: +8-10%)
- keeping separately may be beneficial because males have higher nutrient and energy demand -> diet more suiting them; also they will reach slaughter age faster —> reducing load of slaughterhouse (slaughtering in different days)
- light is important for laying birds but not that important for broilers
