How do we do it??? Some General Facts PROTEIN ESSENTIAL AMINO ACIDS. A general overview. Life Stage Nutrition for Birds

Transcription

1 Life Stage Nutrition for Birds A general overview Barbara Toddes, Nutrition Program Director, Philadelphia Zoo Some General Facts Approximately 8,600 different living species of birds An aviary or zoo may house as many as 500 different species of birds Avian species have numerous different feeding strategies as well as physical specializations (beaks, bills, talons) that limit the types of food they can utilize in captivity Birds are frequently housed in very large mixed species exhibits It is our responsibility to meet the nutritional needs of all these animals and at every life stage How do we do it??? What do all birds have in Common?? Base the feeding program on what the birds have in common at each life stage Lends structure to a program and allows for the general concepts and principals of nutrition to be applied Protein Essential Amino Acids Lipids Essential Fatty Acids Glucose Carbohydrates gluconeogenic precursors Minerals Calcium Phosphorus Manganese Iron Vitamins A, D 3, E Energy PROTEIN Fundamental component of all living cells Essential in the diet of animals for the growth and repair of tissue. ESSENTIAL AMINO ACIDS 20 Amino Acids that are used by organisms to build proteins Birds are unable to synthesize nine of these amino acids due to the lack of specific enzymes A representation of the 3D structure of myoglobin 153 amino acids primary oxygen carrying protein in muscle Amino acids that can not be synthesized in the body are known as essential meaning they must be consumed 1

2 Essential Amino Acids for Birds How do we provide all the essential amino acids??? Arginine Lysine Theonine Isoleucine Methionine Tryptophan Leucine Phenylalanine Valine Complete Protein provides all the essential amino acids Animal protein meat, eggs, whole prey are complete proteins Histidine, glycine and proline can be synthesized but at a rate that is insufficient to meet the bird s needs Grains and seeds do not provide complete proteins - they lack one or more essential amino acid to form complete proteins a combination of grains or seeds are required Life Stage Protein Needs Maintenance balance of amino that reflect the relative rate of obligatory loss of each individual amino acid Growth requirement is greatest at hatch and drops with age. The average requirement through the growth phase is ~ 15X that of maintenance Egg Production the balance of amino acids required for egg laying is similar between altricail and precocial species Protein Needs for Egg Production Birds that lay only a few eggs have an increase protein requirement of about twice maintenance for a week s s duration Birds that lay many eggs are believed to require up to six times maintenance for critical amino acids such as Methionine and Lysine In the wild many birds increase their intake of invertebrates during reproduction, a phenomenon known as protein shift Fat Fat is a generic term for a class of lipids Lipids are the only dietary components that are deposited into tissue with little or no modification Lipids supply energy, essential fatty acids, and pigments Essential Fatty Acids Polyunsaturated fatty acids (PUFA) that are required in the diet Essential because Birds lack the enzymatic capacity to make them For all birds linoleic acid and alpha-linolenic linolenic must be provided. Linoleic acid is the processor for n-6 n 6 PUFA while alpha-linolenic linolenic is the processor for n-3 n 3 PUFA Birds that consume diets high in animal fat may also require arachidonic and eicosapentanoic acid in the diet 2

3 How do we provide all the essential fatty acids??? Fortunately, almost all natural foods that meet the energy requirement of the birds also meet the bird s s fatty acid requirement In most cases, when an appropriate base diet is offered the essential fatty acids will be supplied Triglycerides Birds do not have a requirement for triglycerids per se; however, Triglycerides: The densest energy source in foods In the intestines, triglycerides are split into glycerol and fatty acids Facilitate the absorption of fat-soluble vitamins Increase the palatability of foods for some species Life Stage Lipid Needs Maintenance: The amount of dietary fat required for adequate absorption of fat- soluble vitamins and Carotenoid appears to be about 2% of dry matter Growth& Egg Production: In the birds that have been studied, the requirement for the fatty acid, linoleic acid, is 1% of the diet (90% dry). Dietary alpha-linolenic linolenic acid protects chicks against encephalomalacia induced by vitamin E deficiency; however, no absolute requirement has been determine Carbohydrates Are chemical compounds that act as the primary biological means of storing or consuming energy Glucose is required by all cells, it is a simple monosaccharid sugar Life Stage Carbohydrate Needs Carbohydrates are conditionally essential; meaning either carbohydrates or gluconeogenic precursors must be present The requirement level for carbohydrates is not known; however, there are no natural foods that are deficient in both carbohydrates and gluconeogenic precursors Minerals Dietary minerals are chemical elements required by living organisms Appropriate intake levels of each dietary mineral must be sustained to maintain physical health. Excessive intake of a dietary mineral may either lead to illness directly or indirectly because of the competitive nature between mineral levels in the body 3

4 Calcium Calcium Deficiencies Is the most prevalent mineral in the body and is required in the diet in higher quantities than any other mineral The requirements for calcium are extremely variable, making this mineral the most challenging nutrient to match to animal need Calcium deficiency or the fear of calcium deficiency is most commonly recognized nutritional concern amongst aviculturists Most common causes: Low dietary calcium Excess phosphorus Insufficient Vitamin D 3 Absorption interference due to complexes formed with phytic or oxalic acid Understanding the reason for the deficiency is critical to resolving it Where does dietary calcium come from?? Low in grains and insects, but relatively high in the vegetative part of plants (leaves, roots, leaf buds, and stems). Also in the bones of whole prey If calcium supplementation is warranted, the bioavailability of the calcium in calcium carbonate is 100%. Purified pharmaceutical grade calcium carbonate is available commerically Life Stage Calcium Needs Maintenance: The requirement for calcium is very low, is less than 0.2% of the diet. Growth: Greatest at hatch and decreases as the bird reaches adult weight. The rate of skeletal growth for altricial hatchlings is considerably faster than that of precocial species. The requirement for chickens is 0.9% of the diet. Calcium Needs for Egg Production The requirement for calcium during egg production is very dependent on the number of eggs laid Recommendation for poultry is 2% of the diet for chickens up to 7% of the diet for Japanese Quail Most birds that lay only one egg can utilize bone reserves to supply the acute demand to calcify its shell Birds that lay clutches have a marked increase in the amount of calcium required in the diet on the day the eggs are laid Phosphorus Most important for bone formation Regardless of life stage, high levels of dietary calcium or a deficiency of Vitamin D increases the requirement of phosphorus Maintaining a Ca:Phos ratio of 2:1 for birds at maintenance is critical 4

5 Where does dietary Phosphorus come from?? Dietary phosphorus is contained in a highly available form in all foods of animal origin Vegetative parts of plants Life Stage Phosphorus Needs Maintenance: A maintenance level of 0.1% in the diet is adequate for chickens when the calcium level is 0.2%. Growth: As with calcium the requirement for phosphorus is highest during skeletal growth and declines as skeletal growth declines. Recommendation for chickens is 0.4% (Calcium 0.9%) of the diet. Phosphorus Needs for Egg Production The requirement during egg production is 0.4% of the diet (calcium 2%) Ca:Ph ratio should 4:1, may be as high as 7:1 for some species Phosphorus is needed mostly to restore bone mobilized during egg laying Much of the phosphate that is liberated through bone mobilization is excreted by the kidneys Manganese Essential in the diet but at relatively low levels Many dietary factors negatively impact absorption Phytic acid (phosphorus( compound found in plants) Fiber Calcium Phosphates Iron Cobalt Where does dietary Manganese come from?? Dietary manganese, like calcium and phosphorus, is contained in the vegetative parts of plants. Also present in the bone, liver, pancrease and kidneys of whole prey Unfortunately the concentration of manganese in a food tells little about the value of the food as a manganese source due to extreme variability in bioavailability Life Stage Manganese Needs Maintenance: The requirement for all life stages is less than 70 mg/kg diet dry matter in poultry Growth: Deficiency during growth causes a perosis-like syndrome characterized by shortened and thickened long bones, malformed hock joints and weakened cartilage 5

6 Manganese Needs for Egg Production In laying birds, deficiency of manganese causes thin shells due to the disruption in the synthesis of the organic matrix If manganese supplementation is warranted, manganese in complex with methionine is considered to be the best Manganese is considered to be the least toxic trace minerals Iron Granivores in iron-poor environments are susceptible to deficiencies Frugivores and insectivores commonly feed on very iron poor foods yet are susceptable to iron storage disease in captiveity.. Why? Because brids do not sufficiently decrease iron absorption when iron stores are full Why is Iron important??? Iron is the central atom of the heme group, a metal complex that binds molecular oxygen (O 2 ) in the lungs and carries it to all of the other cells in the body (e.g., the muscles) that need oxygen to perform their activities Without oxygen the cells die Where does dietary Iron come from?? Dietary iron, like calcium, phosphorus and manganese is found in the vegetative part of plants as well as whole prey The digestibility of dietary iron is extremely variable and is influenced by both bird and competing/complementary dietary factors In birds prone to iron storage disease, the stress of captivity appears to play a very important role. Life Stage Iron Needs The iron requirement of poultry and Japanese Quail has been estimated at mg/kg dry matter in a grain based diet. This level appears adequate for all life stages Fat-Soluble Vitamins Found in the diet in association with lipids and are absorbed in the same manner as fatty acids and cholesterol Level of fat needed in the diet for absorption of the fat soluble vitamins is about 2% of Dry Matter Fat-soluble vitamins are stored in the body, excesses are excreted in the bile and lost in the feces Vitamins A and D stores can build to toxic levels 6

7 Vitamin A The most challenging from a nutritional perspective - most likely to be deficient in both wild and captive birds Vitamin A is critical to cell replication, differentiation and preprogrammed cell death In the absence of Vitamin A, epithelial basel cells which are soft and moist, differentiate into keratinizing cells which are hard and dry Where does dietary Vitamin A come from?? Dietary Vitamin A (retinol) is found in the fat and liver of vertebrate prey (but not the muscle) Plants and insects do not contain Vitamin A but are high in B-Carotene, B a carotenoid that has high Vitamin A bioavailability in some species Life Stage Vitamin A Needs Requirement for all life stages is 1.5 IU/g of diet (90% dry) for chickens Maintenance: Birds with inadequate levels of vitamin A in their diet are more prone to infections and often die from infection before any other deficiency symptoms occur Growth: deficiency symptoms include anorexia, poor growth, ruffled plumage, weakness, poor condition and lack of Carotenoid pigmentation in the skin and feathers Vitamin D 3 Birds utilize D 3, to date all the birds tested have very low vitamin D 2 utilization less than 10% that of D 3 Vitamin D 3 is cholecalciferol. Birds can synthesize vitamin D 3 from cholesterol when they receive adequate sunlight Where does dietary Vitamin D 3 come from?? The best source of Vitamin D 3 is the sun Dietary D 3 is prevalent in marine fish due to the presence of phytoplankton and zooplankton. Most other natural foods are low in D 3 Life Stage Vitamin D 3 Needs Maintenance: The recommendation for chickens is 0.2 ICU/g of diet (90% dry) Growth: The recommendation for chickens is 0.2 ICU/g of diet (90% dry). Chicks fed vitamin D-D deficient diets have slow growth and awkward gaits. Advanced deficiency results in rickets Egg Production: The recommendation for chickens is 0.3 ICU/g of diet (90% dry). Thin egg shells is the most obvious symptom of vitamin D-deficiencyD 7

8 Vitamin E An important antioxidant meaning it competes for free radicals much faster than polyunsaturated fatty acids protecting cell membranes from oxidation Influences a number of physiological processes important for immune response Where does dietary Vitamin E come from?? Dietary vitamin E is found only in plants, located mostly in the leaves D-alpha-tocopherol is most biologically active form of vitamin E Supplementation of vitamin E should be done with D-alphaD alpha-tocopherol. Vitamin E is very safe and can be easily supplemented Life Stage Vitamin E Needs Maintenance requirement is dependent on: level of polyunsatuated fats high levels of vitamin A or B-caroteneB low levels of other dietary antioxidants rancid dietary fats selenium deficiency Recommendations for all life stages: The requirement of chickens is only.005 IU/g of diet However, diets that provide iu/g or more have worked well for birds of prey Life Stage Vitamin E Needs Growth: Under severe deficiency encephalomalacia - known as crazy chick disease - characterized by lesions on the cerebellum that cause hemorrhages and edema in the brain. Reproduction: Reproductively active males that are E-dificient E have reduced fertility due to abnormal sperm and low sperm production. Eggs from deficient females appear normal but have low hatchability due to late in shell embryo mortality. Energy Energy is the heat given off by burning a gram of food measured in kilocalories (kcal) Protein = 4 kcal Fat = 9 kcal Carbohydrates = 4 kcal Basal Metabolic Rate Basal Metabolic Rate (BMR) = energy required life processes only The amount of energy consumed by the bird must meet the birds BMR requirement plus the energy required by life stage,, activity, stress and the environment 8

9 BMR Calculations Non-passerine birds: BMR = 78 kcal (Body Weight).75 Passerine birds: BMR = 158 kcal (Body Weight).75 Life Stage Energy Needs Maintenance requirement for energy is defined as the energy intake at which the body weight and body composition remain constant in a healthy, non- reproductive bird living in a normal environment Life Stage Energy Needs Maintenance: Passerines : ~ 2.8 times BMR Calculate 2.8 {158{ kcal (Body Weight).75 Non-Passerines : ~2.5 times Calculate 2.5 {78{ kcal (Body Weight) }.75 } Additional Energy Needs at Maintenance Plus ~38% BMR for foraging Plus ~70% BMR for Cold Climates Plus as much as 14.5 times BMR for Flight Life Stage Energy Needs Life Stage Energy Needs Growth: The energy required for growth depends on the amount of protein and lipid that is deposited daily Cost of Growth = ~ 3.18 kcal/1 g lean ~ 11.4 kcal/1 g adipose Energy needs are greatest at hatch and gradually decline. Egg Production: The energy required for egg production depends on the amount of protein and lipid depostion in the egg Cost of Egg Production = ~ 11.5 kcal/1 g protein ~ 12.1 kcal/1 g lipid Average energy need for growth is ~ 25% above maintenance 9

10 Energy Needs for Egg Production of Different Species Plus 39% of BMR, Plus 140% fo BMR, hawks and owls for shorebirds Conclusion To meet the nutrient requirements of aviary birds it is important to consider the needs that all birds have in common Plus 45% of BMR, for passerines Plus 126% of BMR, for Galligormes Plus 170% of BMR for gulls Plus 180% of BMR, for ducks Basing a feeding program on the needs animals have common lends structure to a program and allows for the general concepts and principals of nutrition to be applied Once the common needs of the animals are met, more species and individual specific needs can be addressed 10