Feed Preference
An experiment was conducted to study the relationship between the previously reported feed preference values of feeds and their particle size and texture characteristics. The effect of individual feed ingredients to be studied was added to a common basal diet containing rice, soybean meal, sunflower oil, and wheat bran. A total of 126 diets were studied, 63 were prepared by replacing rice in the basal diet with another cereal, 29 by replacing the soybean product with different protein sources, 19 by replacing sunflower oil with different lipid sources, and 6 by replacing wheat bran with different fiber sources. The diets were characterized for particle size and texture properties. Results indicated that the texture properties of the feed were more related to feed preferences compared to the effect of particle size characteristics.

Sola-Oriol, D. and co-workers. 2008. Feed preference in pigs: Relationship with feed particle size and texture; J. Animal Sci:

Results of Two Transgenic Soybean Feeding Studies
A genetically modified soybean (Optimum GAT) was produced by insertion of two genes that provided tolerance in the soybean plant to glyphosate, sulfonylurea and imidazolinone herbicides. The objective of this study was to compare the nutritional equivalence of these transgenic soybeans to nontransgenic soybeans in a 42-d feeding trial in broiler chickens. Diets were prepared using processed fractions (meal, hulls, and oil) from untreated soybean plants or from soybean plants treated with a mixture of herbicides. For comparison, additional diets were produced with soybean fractions obtained from a nontransgenic near-isoline and nontransgenic commercial Pioneer varieties. Diets were fed to Ross x Cobb broilers (n = 120/group, 50% male and 50% female) in 3 phases. Starter diets contained 30% soybean meal, grower diets 26% soybean meal, and finisher diets 21.5% soybean meal. Soybean hulls and oil were added at 1.0 and 0.5%, respectively, across all diets in each phase. No statistically significant differences were observed in mortality, growth performance variables, or carcass and organ yields between broilers consuming diets produced with transgenic soybean fractions and those consuming diets produced with near-isoline control soybean fractions. Additionally, all performance and carcass variables from control and transgenic soybean treatment groups fell within the tolerance intervals constructed using data from reference soybean groups. Based on the results from this study, it was concluded that transgenic soybean was nutritionally equivalent to nontransgenic control soybean with a comparable genetic background.

McNaughton, J., and co-workers. 2007. Comparison of broiler performance when fed diets containing event DP-356Ø43-5 (Optimum GAT), nontransgenic near-isoline control, or commercial reference soybean meal, hulls, and oil. Poultry Sci: (86): 2569-81.

A genetically modified soybean (305423) that was produced by insertion of the gm-fad2-1 gene fragment and gm-hra genes into the germline of soybean seeds. Expression of gm-fad2-1 results in greater concentrations of oleic acid (18:1) by suppressing expression of the endogenous FAD2-1 gene, which encodes an n-6 fatty acid desaturase enzyme that catalyzes desaturation of 18:1 to linoleic acid (18:2). The gm-hra gene results in protein enzyme that is used as a selectable marker during transformation. A 42-d feeding trial was conducted with broiler chickens to compare the nutritional performance of these transgenic soybeans with nontransgenic soybeans. Diets were prepared using processed fractions (meal, hulls, and oil) from transgenic soybean plants. For comparison, additional diets were produced with soybean fractions obtained from a nontransgenic near-isoline (control) and nontransgenic commercial Pioneer brand varieties. No statistically significant differences were observed in growth performance (body weight, mortality, feed efficiency), organ yield (liver and kidney), or carcass yield variables between broilers consuming diets prepared with isolated fractions from transgenic or near-isoline control soybean diets. The researchers concluded that based on the results from this study, transgenic (305423) soybeans were nutritionally equivalent to non-transgenic control soybeans with a comparable genetic background.

McNaughton, J., and co-workers. 2008. Comparison of Broiler Performance When Fed Diets Containing Event DP-3O5423-1, Nontransgenic Near-Isoline Control, or Commercial Reference Soybean Meal, Hulls, and Oil. Poultry Sci. (87): 2549-2561).

Feeding Wheat Distillers Dried Grains with Solubles to Broilers
To determine the impact of including wheat DDGS in broiler diets on nutrient excretion and phosphorus characterization and solubility, 125 one-day-old male broiler chicks were fed wheat- and soybean meal-based diets containing 0, 5, 10, 15, or 20% wheat DDGS. There were five replicate pens per treatment, with five birds per pen arranged in a randomized block design. Apparent retention of both nitrogen (N) and phosphorus (P) was determined by using the indicator method. Nutrients excreted per kilogram of dry matter (DM) intake were also calculated. The apparent retention of both N (P < 0.001) and P (P < 0.008) decreased linearly with increasing inclusion rates of DDGS from 0 to 20%. The nutrient output per kilogram of DM intake increased linearly with increased DDGS inclusion rate for N (P < 0.04), P (P < 0.0001), and WSP (P < 0.0003). As the inclusion rate of DDGS increased, the P concentration in excreta increased (P < 0.008), whereas excreta phytate P concentrations decreased (P < 0.01), which led to an increase in water soluble P and the fraction of total P that was soluble. Because the inclusion of wheat DDGS in poultry diets increased N and P output, as well as the solubility of P excreted, the authors indicated that care should be taken when including high levels of wheat DDGS in poultry diets, because increases in N and P excretion are a concern from an environmental standpoint.

Leytem, A.B. and co-workers. 2008. Nutrient excretion, phosphorus characterization, and phosphorus solubility in excreta from broiler chicks fed diets containing graded levels of wheat distillers grains with solubles. Poultry Sci. (87): 2505-2511.