Palatability of Feed Ingredients in Nursery Pigs

Abstract

The objectives of this research were: 1) To evaluate nursery pig preference for diets containing various inclusion levels of dried distillers grains with soluble (DDGS), high protein dried distillers grains (HPDDG) or corn gluten meal (CGM); 2) To evaluate the effect of different qualities of DDGS on nursery pig preference; and 3) To evaluate growth performance and feed preference for diets containing various inclusion levels of DDGS with or without flavor supplementation. For the first objective, 3 double-choice preference experiments were performed using a 2 day assay. In experiment 1, preference for diets containing DDGS (0, 10, 20, and 30%) was examined. A linear decrease (P<0.001) in preference was found with increasing inclusion levels of DDGS on day 1, day 2 and overall. In experiment 2, preference for diets containing CGM (0, 5, 10, and 15%) was examined. On day 1 and overall, a linear decrease (P<0.06) in preference was found with increasing inclusion level of CGM. Preferences for all CGM containing diets were lower (P<0.05) than 50% on day 1, day 2 and overall, indicating preference of the control diet over CGM containing diets, as no preference would result in equal consumption of both feeds (50% of the control feed and 50% of the test feed). In experiment 3, preference for diets containing HPDDG (0, 10, 20, and 30%) was examined. A linear decrease (P<0.001) in preference was found with increasing inclusion levels of HPDDG on day 1, day 2 and overall, and preference for all HPDDG containing diets was less than 50% on day 1, day 2 and overall (P<0.0001). For the second objective, 2 experiments were performed. In experiment 1, preference for diets containing 30% good or poor quality DDGS was examined. DDGS sources were obtained from mills with known good and poor quality DDGS. Color of the sources was observed to ensure poor versus good quality, with the darker source being poor and the lighter source being good quality. Preference for the control diet was not different from the 30% good or poor quality DDGS diets. However, the diet containing 30% poor quality DDGS was preferred (P<0.05) over the diet containing 30% good quality DDGS on day 1, day 2 and overall. In experiment 2, preference for diets containing good quality DDGS (0, 10, or 20%) or poor quality DDGS (0, 10, or 20%) was examined. Inclusion of good quality DDGS linearly decreased (P<0.01) preference on day 1, 2, and overall. For the poor quality DDGS, inclusion of 20% resulted in a preference lower (P<0.05) than 50%. The negative impact of good DDGS on preference was greater compared to the poor DDGS, indicating that poor DDGS may have a higher preference compared to good DDGS. For the third objective, 2 experiments were performed. In experiment 1, growth performance of nursery pigs fed diets containing various inclusion levels of DDGS (0, 10, and 20%) in the presence or absence of flavor was examined. Average daily gain (ADG) and average daily feed intake (ADFI) in the Starter 1 phase were negatively affected (P<0.06) by DDGS inclusion. No other performance parameters, such as feed efficiency and body weight, were affected by DDGS inclusion. ADFI was increased (P=0.02) by flavor in the Starter 1 phase only. No other performance parameters were affected by flavor. In experiment 2, feed preference for diets containing various inclusion levels of DDGS in the presence or absence of flavor was examined. Preference for unflavored and flavored DDGS containing diets was less than preference for the control diet. Presence of flavor decreased preference regardless of DDGS inclusion. Overall, these studies indicate that DDGS, CGM and HPDDG containing diets are not preferred over control diets with corn and soybean meal. However, poor quality DDGS may be preferred over good quality DDGS. Also, addition of the present flavor seems to exacerbate the negative effect of DDGS palatability. Evaluation of volatile components via gas chromatography and headspace analysis in each DDGS and HPDDG sample indicated that compounds associated with rancidity are negatively correlated with palatability, and that the smoky, burnt characteristic of furfural may be palatable to pigs.