..even if you do not have cocci vaccinated birds the nutritional info in the article below is very helpful: http://www.netvaxforpoultry.com/document_library/IDEAproceed.pdf "....The IDEA concept seeks to enhance immunity development and reduce intestinal challenges by coccidia and bacteria without the use of drugs. With improved genetic potential comes increased demand on the intestinal tract for maximum digestion and absorption. A comprehensive understanding of intestinal physiology is imperative..... I Impulse (1 to 14 days) Optimum protein and energy levels as well as vitamins and trace mineral supplementation should be critically reviewed and evaluated in the starter (impulse) feeds. The immune, digestive and temperature regulatory systems are still being developed during this critical stage of the birds life. Newly hatched chicks need immediate access to solid feed and water to stimulate intestinal maturation. This stage determines the quality and number of enterocytes that will develop and be maintained for the rest of the birds life. In order to maximize the full processing genetic potential, it is critical to guarantee maximum development of intestinal enterocytes in this very early phase of grow-out. This critical window of time is also when bones and muscles are formed at maximum efficiency and when intestinal microflora are established. D Digestibility (15 to 28 days) Abrasive or less digestible ingredients in the grower (digestibility) feeds can cause nonspecific enteritis and should be replaced with high quality, highly digestible ingredients. Dietary changes should be avoided at 15 to 21 days to prevent intestinal irritation and subsequent disruption of normal microflora development. Intestinal irritation can lead to infections with secondary invaders, especially bacteria (dysbacteriosis). Full development of the intestinal immune system and enterocytes are completed by this phase of grow-out. Protein levels should be adjusted as needed, since excess undigested protein encourages overgrowth of undesirable bacteria and could contribute to the development of dysbacteriosis. Dietary fat should be of high quality and easily digestible as well...... ......Recent trials have confirmed that performance is enhanced when digestibility of the protein fed is improved during the time that immunity is developing..... (see article for info specific to broilers).... ....However, another aspect that can impair the digestion of lipids and protein is the presence of soluble non-starch polysaccharides (pentosans, beta-glucans and pectins) in the diet. The younger the chicks are, the worse the effects are of these polysaccharides. These substances promote an increase in intestinal viscosity, slowing the diffusion velocity of substrates and enzymes and compromising their interaction with the enterocytes. These substances also increase the presence of microorganisms in the small intestine (Schutte,1997)........So, first week diets should preferably not contain wheat, rye, barley or oats, since these ingredients are high in soluble non-starch polysaccharides. Immune system development The development of the immune system starts during the embryonic stage and continues during the first week post-hatch. Casteel et al (1994) mentions that a delay in water and feed consumption promotes depression of the immune response. According to Klasing (1998), chronic deficiency of micronutrients can be more significant than the deficiency of energy and proteins.Friedeman and Sklan (1997) demonstrated that broilers fed vitamin A-deficient diets are less resistant to infectious challenges, and the immunocompetence of young chicks is maximized when the level of vitamin A is 10 to 20 times higher than the level suggested for maximum growth....... ....Yi et al (2005) observed that broilers fasted for 48 hours after hatch had dramatically decreased weight gain and feed efficiency during the first 2 weeks after vaccination against Eimeria maxima. Ad libitum access to feed or hatchling supplement for 48 hours followed by feeding ad libitum was beneficial to early growth performance in broiler chicks. On day 7 post-hatch, it was shown that the fasting group (48 h) had less developed intestinal villi and disrupted intestinal integrity compared to birds fed ad libitum immediatelyafter placement. .....It is extremely important that broilers start to eat solid feed immediately after hatch, stimulating changes in intestinal structures and secretions. Noy and Sklan (1997) found that the yolk sac is used faster by chicks being fed than by chicks that are fasting. Thus, leaving chicks without feed in early life prevents the early stimulation of nutrients in the digestive system and reduces the use of available nutrients in the yolk sac, which are essential for early chick development...... ...Moreover, if lipids are not fully absorbed, which seems probable, or if they are oxidized in the feed or in the lumen, they can cause serious damage to 1-week-old chicks.....Peroxides, produced by oxidative rancidity of lipids, compromise digestive tract anatomy and impair the availability of several nutrients such as fat soluble vitamins........ According to Petersen (1971), referred by Krogdahl (1985), animal fat digestibility in chicks significantly increases with age. This author suggested the equation D = 60.0 + 4.0 A 0.07 A2 (r=.81), where D represents animal fat digestibility and A the bird age in weeks. As it can be seen by the equation, animal fat digestibility is very low in the first week of life. Therefore, undigested fat will remain in the intestinal tract and may be oxidized. It may also be available, as an energy source, to microorganisms present in the intestine or, at least, promote a process of steatorrhea......The higher the level of free fatty acids in feed, the worse the lipid digestibility. Wiseman and Salvador (1991) showed that free fatty acids impaired lipid digestibility, and this effect was more marked when the lipid source was tallow and palm oil instead of soybean oil....In some species, the excess of feed intake in early life promotes maturation of fat cells and increases their number. However, this evidence is not confirmed in broilers..... ....Minerals and vitamins Laganá et al (2004) observed that supplementation with organic Zn and Se (40 and 0.3 ppm respectively and vitamins E and C 100 IU and 300 ppm, respectively) during the raising period resulted in the best feed conversion at 14 and at 35 days. No statistical differences were observed between supplementation only with minerals or with vitamins and minerals together. Conclusion Based on these observations, it is possible to determine what chickens need during the first week of life to get the best performance response later. The anatomical, physiological and nutritional aspects are very different during this short period of time, but can affect their entire lives....... " This is but a small excerpt from this extensive paper and though it is initially geared towards broilers, much of the info is applicable to all poultry as I have ran across the info in other (applicable to non-broiler) studies/articles.