Collaborative research efforts across disciplines typically result in more insight toward the hypothesis being tested due to the omnibus nature of the projects. For example, nutritional experiments evaluating a nutrient response will benefit greatly by incorporating biochemical, physiological, and immunological endpoints for measurement. Clearly, commercial poultry producers do not have the luxury of focusing on specific disciplines when field problems occur. Hence, in practice interplay exists among nutrition, genetics, management, and diseases. Dietary composition impacts immune function of the chicken. As research in the area of nutritional immunology has increased, it is becoming apparent that nutrient needs for immunity do not coincide with those for growth or skeletal tissue accretion. This review is not a comprehensive assessment of nutrient needs for immunity in the chicken. Rather, this review is concerned with nutritional modulation of immunity in broilers that offers insight for nutritionists and researchers to implement nutritional regimens to reduce the severity of disease and to test or validate nutritional regimens that heighten immunity. Nutritional modulation of the hen diet and in ovo nutrient modulation to improve chick immunity and disease resistance are discussed.

Two experiments were conducted to evaluate the effect of amino acid (AA) injections in ovo in Cobb broiler breeder eggs on hatchability and subsequent chick BW. In Experiment 1, moisture, crude fat (CF), and CP were analyzed over time during incubation (Day 0, 7, 14, and 19 of incubation). Moisture, CP, and CF of the embryo increased, and moisture, CP, and CF of eggs decreased, as incubation time increased (P < 0.05). Combined egg and embryo AA contents, except Gly and Pro, decreased (P < 0.05) as incubation time increased. However, the pattern of AA in the egg did not change as the embryo developed. In Experiment 2, AA were injected into the yolk or air cell at Day 0 and 7 of incubation. Hatchability was reduced (P < 0.05) when AA were injected at Day 0 of incubation. However, when the AA solution was injected into the yolk sac at Day 7 of incubation, hatchability was not affected, and BW of chicks increased relative to egg weight prior to incubation. These results suggest that in ovo administration of AA may be an effective method of increasing chick BW at hatch.

Betaine, a donor of labile methyl groups, can spare choline and methionine but cannot replace these compounds in poultry diets. Betaine is synthesized from choline by choline oxidase and it can donate methyl groups to homocysteine to form methionine. Physiologically, betaine is one of several compounds used by cells to regulate osmotic pressure. Among the potential benefits of its inclusion in poultry feeds are sparing choline, carcass fat reduction and aiding cell osmoregulation. Some feed ingredients are natural sources of betaine per se. This review considers the metabolism, functions and applications of betaine in poultry. Betaine, metabolic by-product or vital methylating agent? Life BELL, A. (1995) What's the word on betaine? Pork95, February, pp. 26-27 BURG, M.B. (1994) Molecular basis for osmoregulation of organic osmolytes in renal medullary cells. The osmoprotective properties of urine for bacteria: The protective effect of betaine and human urine against low pH and high concentrations of electrolytes, sugars, and urea. Journal of Infectious Diseases 152: 1308-1316 CHAMBERS, S.T. and KUNIN, C.M. (1987) Osmoprotective activity for Escherichia coli in mammalian renal inner medulla and urine. The efflux of betaine from rat-liver mitochondria, a possible regulating step in choline oxidation. Biochimica et Biophysica Acta 291: 557-563 DE RIDDER, J.J.M. and VAN DAN, K. (1975) Control of choline oxidation by rat-liver mitochondria. Biochimica et Biophysica Acta 408: 112-122 261: 5872-5877 123 Sciences 32: 771-774 Journal of Experimental Zoology 268: 171-175 DU VIGNEAUD, V., CHANDLER, J.P., MOYER, A.W. and KEPPEL, D.M. (1939) The effect of choline on the ability of homocystine to replace methionine in the diet. loicrnal of Biological Chemistry 131: 57-76

Cornell K-strain White Leghorns and broiler chicks were raised to 7 wks and 3 wks of age respectively, with diets containing various levels (0, 10, 100, 1,000 and 10,000 ppm) of Spirulina platensis from day of hatch. Chicks in all treatment groups had comparable body weights. While bursal and splenic weights did not change, the K-strain chicks had larger thymuses (P < or = .05) over the controls (0 ppm group). No differences were observed in anti-sheep red blood cells antibodies during primary response. However, during secondary response, K-strain chicks in all Spirulina-dietary groups had higher total anti-SRBC titers with 10,000 ppm group being the highest (6.8 Log2) versus the 0 ppm (5.5 Log2) group. In broiler chicks, a one Log increase in IgG (P < or = .05) was observed in 10,000 ppm group over the controls. Similarly, chicks in 10,000 ppm Spirulina group had a higher PHA-P-mediated lymphoproliferative response over the 0 ppm controls. Macrophages isolated from both K-strain (10,000 ppm group) and broilers from all Spirulina groups had higher phagocytic potential than the 0 ppm groups. Spirulina supplementation at 10,000 ppm level also increased NK-cell activity by two fold over the controls. These studies show that Spirulina supplementation increases several immunological functions implying that a dietary inclusion of Spirulina at a level of 10,000 ppm may enhance disease resistance potential in chickens.

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Two experiments were conducted to evaluate the effects of two dietary levels of lysine and four dietary levels of threonine in a factorial arrangement on broiler growth, carcass traits, and immunity. In both experiments, 120 broilers were allocated to each of 56 floor pens (6,720 total broilers). In Experiment 1, two levels of lysine (1.10 and 1.20% of diet) and four levels of threonine (0.68, 0.74, 0.80, and 0.86% of diet) were fed to broilers from 1 to 18 d of age in a sorghum-peanut meal diet. Body weight gain, feed:gain, mortality, and cellular and humoral immunity were measured. In Experiment 2, all broilers received a common basal diet up to 18 d of age. Experimental diets were fed from 18 to 34, 34 to 44, and 44 to 54 d of age. Two levels of lysine [100 and 105% of NRC (1994) recommendations] and four levels of threonine [83, 92, 100, and 108% of NRC (1994) recommendations] were included in the experimental diets for each age group (seven replications per treatment). The diets consisted of wheat (soft), corn gluten meal, soybean meal, and meat and bone meal Weight gain, feed:gain, mortality, and carcass traits were measured at 54 d of age. In Experiment 1, increasing dietary lysine from 1.10 to 1.20% from 1 to 18 d in broilers improved (P < 0.001) BW gain (453 vs 488 g) and feed:gain (1.39 vs 1.33). No interactions between lysine and threonine were observed in Experiment 1. Differences in immune parameters or mortality were not observed. In Experiment 2, an interaction in 18 to 54 d weight gain occurred with the highest gain in broilers receiving dietary lysine and threonine levels equivalent to 100 and 83%, respectively, of NRC (1994) or lysine and threonine at levels of 105% and 100% of NRC (1994), respectively (P < or = 0.05). Supplemental lysine (105% of the 1994 NRC) improved (P < or = 0.01) 18 to 54 d feed:gain (2.30 vs 2.26). No differences in mortality occurred. Supplemental lysine increased preslaughter weight (P < or = 0.05), but differences in carcass yield were not observed. Breast fillet yields were the highest (P < or = 0.03) in broilers receiving 100% of NRC lysine and 83 or 92% of NRC threonine or 105% of NRC lysine and 100 or 108% of NRC threonine. In conclusion, additional lysine improved feed:gain independent of threonine from 1 to 54 d of age. However, lysine and threonine interact to increase weight gain and breast fillet yields.

A major goal of many poultry producers is to attain good flock liveability. Historically, most poultry producers have manipulated environmental conditions and management to maximize bird health. In the past two decades there has been much research into nutritional regimes that improve bird health through immunomodulation. Commercial poultry environments contain ubiquitous micro-organisms that continuously challenge the immune system. Nutritional supplements that enhance immune system function may improve flock performance and be economically advantageous. This paper reviews the literature on zinc-methionine and the avian cellular immune system. Current knowledge of the effects of zinc on many animal models is reviewed and a hypothetical mechanism for the action of zinc-methionine on this system is discussed. The role of metals in the production of toxic oxygen metabolites by mononuclear phagocytes. in: Nutrient Modulation of the Immune Response (Ed. Cunningham-Rundles, S.), Marcel Dekker Inc, New York, pp.127-140 CORRIER, D.E. and DELOACH, J.R. (1990) Evaluation of cell-mediated, cutaneous basophil hypersensitivity in young chickens by an interdigital skin test. Poultry Science 69: 403-408 COUSINS, R.J. (1985) Absorption, transport and hepatic metabolism of copper and zinc: Special reference to metallothionine and ceruloplasmin.

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