In vivo digestibility of corn and sunflower intercropped as a silage crop

Six nonlactating Holstein cows in a 3 x 3 Latin square total collection digestion trial were used to evaluate three low DM (less than 26%) silage types: 1) corn; 2) corn and sunflower intercropped and 3) sunflower. Feeding periods consisted of a 7-d adjustment followed by a 5-d collection period. Dry matter intake was similar for the three treatments; 12.5, 12.1, and 12.0 kg, respectively. Percent apparent digestibilities for DM, NDF, and N for corn and corn-sunflower were similar and greater than for sunflower: DM (69.6, 68.2, 57.4); NDF (68.1, 61.5, 51.6); and N (66.3, 66.5, 63.6). No differences were observed for digestibilities of ADF, hemicellulose, starch, or for N retention. Percent ether extract digestibility was greatest for corn-sunflower and sunflower silage when compared with digestibility of corn silage (82.5, 77.9, vs. 66.3). Major changes in rumen fermentation patterns were not observed as evidenced by rumen molar proportions of propionate, isobutyrate, isovalerate, valerate, or acetate to propionate ratios. No difference was observed for rumen NH3 N (2.7, 3.2, 4.1 mg/dl, respectively). Corn and sunflower intercropped silage had intermediate concentrations of fat, fiber, and protein when compared with those of corn or sunflower silages.