Nutrition Tca

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Growth

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• Measured by increase in BW, requires large margin above maintenance
• Increased need for nutrition: rapid growth and energy to match young behaviour.
• Growth rate is at its highest in early life, declines towards puberty and slows further until maturity
• Nutrient requirements per unit of BW highest in the very young and decline as growth rate declines
• Different organs and tissues grow at different rates, influencing changing nutritional needs throughout growth period
• Mammalian neonates acquire most nutrition from mother’s milk. GIT has limited capacity
• The GIT is permeable to large molecules. Colostrum contains a large supply of globulins and provides nutrition, antibodies, vitamins and minerals.

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Nutritional requirements for growth in dogs

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• Early weaning (3-4 weeks in dogs) = start moving onto solid foods – highly palatable, energy & nutrient dense foods most suitable.
• Fully weaned (6-8 weeks in dogs) = feed regular small meals.
• Very dependent on breed but most have 50-60% normal adult weight by 5-6 months.
• Feeding regime VERY important in giant breeds as too rapid growth can lead to skeletal development problems.
• Energy at weaning = approx double adult maintenance; then gradually drops to normal level over time.
• High energy requirements means high food intake so regular meals needed to achieve this – start at min 4 meals per day then gradually decrease.
• Protein and Ca (related to P) requirements higher for growth (muscle & bone).
• Must not feed puppies ad lib as will become obese very quickly.

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Nutritional requirements for growth in cats

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• Early stages dependent on milk, aim for 100g body weight increase per week.
• Weaning starts at 3-4 weeks finishes around 7-8 weeks.
• Once weaned, the ability to digest lactose reduces until some adult cats show complete intolerance.
• Kittens should be fed ad lib as won’t overeat.
• Energy requirements peak at 10 weeks (840kJ/kg BW) and stay high until 6 months old.
• Protein requirements (high in cats) must be about 10% greater for growing kittens.

• Ca:P ratio must be controlled to prevent bone deformities.
• Must contain taurine to allow correct growth.
• 75% adult weight achieved by 6 months so can then feed as adults.

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Nutritional requirements for growth in horses

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• Foals able to digest lactose when born but lose this ability with age (over 3 years can have adverse reactions).
• Height increases faster than weight - at 1 year they are 90% adult height but 60-75% adult weight - so must meet Ca & P requirements for bone growth (1:1 up to 3:1)
• Protein requirements highest during first month (DP:DE = 10g/MJ) then decrease (6g/MJ)

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Nutritional requirements for growth in birds

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• Very rapid increase in BW
• Also have to produce feathers if altricial (e.g. budgie).
• Large proportion of energy intake goes to growth (62-73% in Robins) which decreases with age/development.
• Parental food supply needs to allow for this so should be doubled until the last fledgling has left the nest.
• Diets deficient in EFAs (particularly linoleic acid) show retarded growth in chicks within 1 week, followed by dermal problems and dehydration (birds classically exhibit excessive water intake). If not corrected, feathering deteriorates, feed utilisation is impaired, disease resistance falls and the chick will die. The same requirement exists for chicks and adults (2% of dietary ME) but chicks are less resistant to deficiencies.
• As well as the normal essential amino acids, chicks seem to require dietary glycine and proline (for feathers & collagen) to achieve maximal growth & development.
• Increased need for protein (to match energy) during rapid growth – at least 25% of diet for budgies which matches content of crop milk.
• BUT excessive protein can depress growth in older cockatiel chicks (Roudybush & Grau, 1986).
• Once adult weight achieved (6 weeks for budgie) normal adult protein levels fed.

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Reproductive nutritional requirements for birds

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• Definite link between folic acid deficiency and reduced reproductive success in mammals.
• Energy requirements increase during egg production in birds.
• Budgie egg = 2.5g
• Energy content of egg = 6.5kJ/g
• Energy to produce 1 egg = 16.5kJ
• Number of eggs per clutch = 5 (average)
• Extra energy required to lay one clutch = 80kJ
• Energy requirements of parent birds are fairly constant during incubation but increase dramatically following hatching due to gathering food for young.
• Birds have a higher protein demand during the reproductive season for both egg production and ‘crop milk’ – studies suggest 18% diet as protein (about twice normal).
• Birds have an increased Ca demand to produce eggs – egg shell = 98% calcium carbonate - otherwise can get soft/thin shelled eggs or egg-binding.
• Vitamin D deficiency can result in thin egg shells, reduced hatching success & embryos with malformed or partially formed beaks.

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reproductive nutritional needs horses

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Mares fed a fat-supplemented diet maintained energy balance (ate less and had a constant BW) but had a higher pregnancy rate (100% vs 89%) and needed fewer cycles per conception (1 vs 2) (Davison et al., 1991).