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A review of the literature regarding Low Protein diets (LCP) for broilers reveals that by using crystalline amino acids, dietary CP could be reduced in each phase safely by a factor of 10% (a figure fairly consistent with turkeys but quite low with that found for ducks and swine) from the respective NRC (1994) levels; the calculated minimum dietary CP levels thus appeared to be 20.7, 18.0, and 16.2% respectively for 0-21, 21-42 and 42-56 days of age. It is, however, noted that the magnitude of protein reduction, without affecting the growth performance of broilers, could have been increased depending upon the EAA concentration and balance of LCP vs. control-CP diets as well as the response criteria used (gain vs. composition of gain). Further reduction in dietary protein results in depressed live/carcass yield in almost all cases.Depressed feed intake appears partially to explain the negative effect of LCP diets in some cases. Addition of NEAA-like glycine above the current NRC recommendations has shown partially to alleviate the negative effect of LCP diets indicating imprecision of our knowledge about NEAA (like glycine, serine and proline etc) requirements of broilers under these conditions. The dietary NEAA/EAA ratio seems to be an important, though poorly understood, factor in defining the performance of broilers fed on LCP diets. It seems that regardless of the absolute amounts of dietary amino acids, performance tend to be depressed when NEAA/EAA ratio is decreased from 50/50; thus the NEAA level of about 50% of protein seems "minimum" state of adequacy. More work is needed before a precise role of the ratio of nitrogen coming from NEAA vs. EAA is proposed. A wider NE:ME in LCP diets seems to explain the higher body fat accretion on these diets; more work on how dietary NE:ME ratio modulates the growth performance of broilers, and how it interacts with different genetic stocks (lean vs. fat lines) is warranted.

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Ascites is a complex problem caused by many interacting factors such as genetics, environment and management. Many nutritional, medicinal and management strategies have been proposed to alleviate the problem. Higher levels of dietary vitamin C and E along with selenium yeast might be beneficial, presumably because of their role in improving cellular integrity. Oils rich in n-3 fatty acids have been shown to reduce pulmonary hypertension and, consequently, ascites incidence. The potential use of flax oil has already been demonstrated, whereas the effects of other oils rich in n-3 fatty acids (fish, linseed and canola oils) remain to be investigated. The assessment of the effects of dietary electrolyte balance on ascites incidence seems to be a promising field of research in broiler nutrition. In general, reducing the dietary level of salt (NaCl) and adding bicarbonates to the diet and drinking water have been proposed as potential "cost-effective" methods to reduce ascites incidence. The use of nutrients/drug agents that increase the vascular capacity of the lungs or decrease the pulmonary vascular resistance may help to alleviate the problem, but economic and local feed regulations might restrict such use. Diuretics have also shown positive effects, presumably because there is a reduction of sodium and fluid retention in the body; litter humidity however must be closely monitored if diuretics are continuously administered. As the high metabolic rate (fast growth) is a major factor contributing to the susceptibility of broilers to ascites, early-age feed or nutrient restriction (qualitative or quantitative) or light restriction in order to slow down the growth rate seem practically viable methods, since final body weight is not compromised. Optimization of the house temperature and ventilation in cold weather seem helpful practices to decrease ascites incidence. Under practical conditions, it might be interesting to test the additive effects of different approaches when used in combination

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