PERFORMANCE AND NUTRIENT DIGESTIBILITY IN WEANLING PIGS AS INFLUENCED BY YEAST CULTURE ADDITIONS TO STARTER DIETS CONTAINING DRIED WHEY OR ONE OF 2 FIBER SOURCES

Three experiments were conducted using crossbred weanling pigs (7.2 to 8.6 kg; 25 to 29 d of age) to determine the effect on performance and nutrient digestibility of .75% yeast culture (YC) additions to starter diets containing whey or one of two fiber sources. An 18% CP corn-soybean meal basal diet was used in all experiments. In Exp. 1 (n = 192), the addition of YC did not affect ADG, ADFI, or gain: feed ratios (G:F) of pigs fed diets without or with 15% dried whey in two 5-wk trials. In Exp. 2 (n = 174), ADG and ADFI were not affected by YC addition to diets containing no added fiber, 8% soybean hulls (SH), or 8% peanut hulls (PH) in two 5-wk trials. The addition of SH or PH did not affect ADG or ADFI; however, a YC x SH interaction (P <.05) and a YC x PH interaction (P <.10) for G:F indicated that the addition of SH or PH to the diet in the absence of YC reduced G:F, but in the presence of YC, G:F were maintained. In a 3-wk grower phase of one trial in Exp. 2 (n = 54), SH and PH additions decreased ADG (P <.005), whereas YC additions improved ADG (P <.01), particularly for pigs fed diets that also contained SH (P <.05). In Exp. 3 (n = 96), pigs fed diets containing YC and 8% PH had an overall ADG similar to that of controls, whereas pigs fed diets containing YC alone or diets containing both YC and 16% PH tended to have lower overall ADG than control pigs (P <.10). Gain:feed ratios were decreased by PH inclusion (P <.01) and by supplemental YC (P <.05). In Exp. 3, the addition of PH linearily decreased the apparent digestibilities of DM (P <.001), N (P <.02), NDF (P <.001), and ADG (P <.03) and increased the apparent absorption of P (P <.02), but coefficients were not influenced by YC inclusion. In summary, YC additions had no effect on ADG and ADFI, variable effects on G:F, and no effect on apparent digestibilities of DM, N, NDF, and ADF and the apparent absorption of P. The inclusion of PH linearly decreased G:F and digestibilities of DM, N, NDF, and ADF but increased apparent absorption of P.