Evaluation, utilization and improvement of the nutritional quality of feed grains for poultry

Graduation date: 1979Several experiments involving broilers, chicks, layers, roosters,\ud poults and breeder turkeys were conducted with the primary objective\ud of examining research methods for evaluating poultry feed grains, their\ud additives and supplements. A secondary objective was to improve and\ud maximize the production responses of poultry fed locally grown grains.\ud Feed grain research approaches were divided into three categories:\ud (1) evaluation of feed grains for energy and protein quality, (2)\ud utilization of the nutritional quality of feed grains and (3) improvement\ud of the nutritional quality of feed grains through the use of dietary\ud additives and supplements.\ud The study was initiated by using some traditional methods for\ud evaluating the nutritional quality of feed grains. The true metabolizable\ud energy (TME) method (a refinement of the commonly used apparent\ud metabolizable energy method) was found to be a rapid and economical\ud method for determining the energy values for new feed grains.\ud Another commonly used method- the Protein Efficiency Ratio - was\ud tested using Japanese quail and turkey poults. While the method was\ud fairly accurate in rank comparisons for grains fed to quail and poults,\ud the method was found to be inadequate for the type of information\ud required for the evaluation of feed grains for use under practical\ud formulation procedures.\ud A re-evaluation was made for the type of information required to\ud adequately evaluate a feed grain. It was decided to test feed grains\ud on the basis of the utilization of their nutritional quality. It was\ud found that wheat in protein adjusted rations not only replaced corn in\ud the ration, but also replaced supplemental protein (soybean meal, etc.).\ud In addition to production responses, the protein replacement value of a\ud feed grain was proposed as an important consideration in the evaluation\ud of new feed grains.\ud The ability of a feed grain protein to replace supplemental protein\ud in a ration was further examined through use of low-protein rations\ud supplemented with amino acids. It was shown that low-protein broiler\ud rations (18% protein) supplemented cumulatively with lysine, methionine\ud or threonine at NRC levels equivalent to a practical 23% protein ration\ud gave variable results. The best body weight gain was obtained when the\ud low-protein ration based on Red wheat was supplemented with all three\ud amino acids. However, this treatment resulted in the poorest feed\ud conversion.\ud Low-protein laying hen rations (13% protein) based on Yamhill wheat\ud and supplemented with 0.1% lysine and 0.1% methionine were found to give\ud comparable results in egg production with a corn or wheat based control\ud for normal-sized laying hens. A biotin-like dermatitis condition was\ud found with dwarf layers fed either corn or wheat based rations.\ud An examination of dietary additives and supplements to grain rations\ud was made using an experimental design approach. In conventional studies,\ud xanthophyll was found to not be as effective as noted in earlier studies.\ud A commercial enzyme (Nopgro) was found to be effective in significantly\ud improving production responses for poults and turkey breeder hens fed\ud wheat rations. Broilers fed a Red wheat ration formulated on a protein\ud adjusted basis with corn and supplemented with 4% animal fat and 55 ppm\ud zinc bacitracin significantly increased body weight and improved feed\ud conversion when compared with birds fed a practical corn based ration.\ud Poult and broiler studies showed non-significant differences in body\ud weight gain with the addition of animal fat. Subsequent studies using\ud response surface methodology showed that the primary effect of animal\ud fat in grain rations for young birds is on feed conversion and not body\ud weight gain.\ud Full factorial experiments were evaluated as an approach to screen\ud dietary supplements and additives for wheat based poultry rations. Five\ud dietary additives or supplements were considered - 4% soybean oil (quail)\ud or animal fat (broiler chicks), biotin, an enzyme (Nopgro), xanthophyll,\ud and zinc bacitracin. For quail chicks, the only significant response was with soybean oil. Broiler chicks had a significant response with\ud both animal fat and zinc bacitracin.\ud Full factorial designs were found to be effective for evaluating\ud several qualitative dietary variables and their interactions. Response\ud surface methods were effective in examining and/or optimizing responses\ud of quantitative dietary variables