Abstract:
RECENT ADVANCES ON THE NUTRITION OF GAME BIRDS PRAN VOHRA iSummary The information on the nutrient requirements of game birds, and the suggested levels of nutrients in their diets is summarized. As all species of-game birds have the same relative amounts of amino acids . in their carcass, they should have similar amino acid requirements. The dietary protein requirement depends upon the rate of protein deposition in their,carc&s. .Least cost formulation of a game bird diet is described. I. INTRODUCTION In their,natural habitat, the game birds .consume a variety of . foods at anytime. The availability of foods depends upon the season and its abundance. The baby chicks consume more of animal matter than the adults. The game birds, in general, are quite cosmopolitan in their food habits and relish cereals, seeds of weeds and grasses fruits, berries, leafy green vegetation; snails, earthworms; insects and their larvae; pieces of snakes, mice, lizards, and many.other animals. It would be impractical to provide this gourmet menuto birds. raised in large numbers in captivity. However, the game birds do equal,ly well on diets blended from the same ingredients as'are used in poultry diets. The diet provides metabolizable energy, essential and non-essential amino acids, essential and non-essential lipids, carbohydrates, minerals, vitamins and other essential nutrients. Before we could formu,late game bird diets, we must have an idea about their quantitative need for the various nutrients, and the nutrient composition of various ingredients available for blending. The formulation of diets is a mere exercise to match the nutrient requirements of birds with a blend of nutrients from the available ingredients at an acceptably minimum cost. II . NUTRIENT REQUIREMENTS. OF GAME BIRDS The meagre information about the nutrient requirements of some game birds, turkeys, ducks and geese as compiled by the National Academy of Sciences (NAS, 1977) is given'in Table 1. The data in parenthesis are estimated values not derived from direct experiments. The paucity of information is evident from this table. We know more about turkey poults of O-4 weeksof age than aboutthe rest of game birds. Our experience indicates that most of the game birds grow normally iffedthe turkey starter diets containing 2800kcal/kg metabolizable energy and 28% or 24% crude protein. In the lattercase, the amino acid levels are also reduced proportionally. No statistically significant differences in the body weights of pheasants, partridge or cot' urnix fed either 25%, 30% or 35% crude protein were observed by the time thev reached an age of 10 weeks, 14 weeks' and 6 weeks, respectively ( V o h r a , 'i973). Department of Avian Sciences, University of California, Davis, CA 95616 In absence of more information, the nutrient requirements.of turkeys can be used as desirable levels to attain in diets for game birds. This supposition is amply justified if we scrutinize the data on the profiles of amino acids in the carcass of various game,birds as in Table 2. The data are for carcasses devoid of feathers and digesta (USDA, 1979, Gertonson et al., 1974). The m&in difference between the wild and domesticated species is in their carcass fats. 'The wild species have a lower fat content. But the protein content of the carcass on a fat free' basis is about the same and.averages at 22.5%. The amino acid profiles of carcass protein are quite similar relative to an assigned value of 100 for lysine. The implication' is that the relative amounts of various essential amino acids in all animal . carcasses are similar (Williams et al., 1954);. In all probability, all animals need relatively all the essential and unessential amino acids in the same ratios in their diets. As we have a better idea about the nutrient requirements of turkey poults, we could use similar diets .for growing game birds. III . DIETARY PROTEIN REQUIREMENTS. The average body weights of some species of game birds and their cumulative feed consumptions are give,n in Table 3. From these data, we can calcul.ate the growth rates of these species by using the logistic equation (Robertson, 1923) where K is growth'rate, W = body weight at time t and Wo = initial body weight at anytime to, and may be considered equal to hatching weight at to = o. The growth rates (K) calculated from Table 3 are presented along with growth rates of broiler chickens,turkeys and ducks in Table 4. The time needed to double the body weights is equal to 0.693/K. Domestic ducks are the fastest growing'species followed by turkeys, chickens, pheasants, partridge and quail. However, a good part of this ' increase in body weights of ducks and broilers is due to deposition of. The game birds are less fatty. If we should consider the rate fat 'of protein deposition by multiplying the growth rate (K) with the crude protein (C.P.) content of the carcasses, these species would be ranked in the following descending order: turkeys, pheasants, chickens, quail, partridge and ducks.. The rate of protein .deposition is a better measure for estimating protein requirements than the rate of growth as measured from body weihht. The turkey poults are started on diets containing 28%'crude protein, and other species perform.optimally on diets containing about 24% crude protein. Domestic ducks need less protein than chickens. Partridqe are started on diets containing 25% protein. From the rate of . protein deposition, partridge should need about as much protein in their diets as needed by ducks. However, the protein requirement is related to the dietary energy content also. IV . SUGGESTED LEVELS OF NUTRIENTS The levels of nutrients suggested in Table 5 may be used for formulation of game bird diets. The level of vitamins are satisfactory in .meeting the requiremtns of birds, yet some nutritionists tend to add vitamins A and D at double the levels suggested here. V. NUTRIENT CONTENT OF INGREDFENTS The nutrient contents of some of the most commonly used ingredients as summarized by NAS (1977). The list covers a total of 43 nutrients for.73 ingredients. We select a reasonable number of these ingredients which are easily available to us.and ,usingtheircurrent prices, we formulate least cost diets'to choose blends of ingredients which meet our specifications. FORMULATION OF DIETS The diets given in Table 6 meet the nutrient requirements'of upland game birds. However, we have switched over to least cost formulations using a microcomputer system program developed by Hempleman and Burger ,(1980). The constraints used along with the price list of ingredients used by us are given in Table 7. The results of a'computer print out to meet these specifications are given in Table 8. The calculated nutrient contents, and the range of prices of individual ingredients over which the composition would not change is also provided. We are using these types of diets for game birds for their optimal . performance (Woodard et al., 1977). REFERENCES 'Nutrient Requirements of Poultry, 7th Revised Ed.' (NatNAS (1977). ional Academy of Sciences, Washington, DC.). GERTONSON, E.H., DAWSON, L.E. and COLEMAN, T.H. (1974). Poultry Sci. 53:1819. HEMPLEMAN,' S. and BURGER, R.E. .(1980). Personal communication. ROBERTSON, T.B. (1923). . 'The Chemical Basis of 'Gro$vth and Senescenei' (Lippincott). SCOTT, M.L. (197). In 'Breeding Biology of Birds' (National Academy '. of Sciences,. Washington, D.C.). USDA (1979). ton, 'AGR. Handbook No. 8-5.' (U.S. Dept. of Agric., WashingDC.). . . Feedstuffs', 45: Aug. 20.. - ' VOHRA, P. (1973). . `WILLIAMS, H.H,, CURTIN, L.V., ABRAHAM, J., LOOSLI, J.K. and MAYNARD, ', (19541.5. Biol. Chem. 208:277. . WOODARD, A.E., VOHRA, P. and SNYDER, R.L. (1977). Poultry Sci., 56: 1492. 125 TABLE 4 - Growth rates of some.species of birds and' the time needed to double their body weights over first.6 weeks. TABLE 5 -Suggested Levels of Nutrients in Diets of Game Birds 127 TABLE 6 - Composition of some diets for upland game birds (inclusions, g/kg diet) TABLE 7 -' Constraints used in diet formulation and prices of ingredients. . 128 TABLE 8 -. Least cost formulation for game bird starter . .. diet (inclusions, g/kg' diet)