Effect of feeding processed soybean as replacement for soybean meal on performance, physically effective fiber of diet, feed intake, and chewing behavior of mid-lactating Holstein dairy cows

The effect of feeding roasted- or extruded soybean and their equal combination instead of soybean meal on feed intake, milk yield and milk composition, meal pattern and chewing behavior was evaluated using four multiparous (DIM = 113 ± 14) and four primiparous (DIM = 96 ± 20) Holstein dairy cows. Cows were used in a replicate 4 × 4 Latin square design with 21-d periods. Experimental diets were: 1) diet containing soybean meal (13.88% of dietary DM); 2) diet containing roasted soybean (15.22% of dietary DM); 3) diet containing extruded soybean (15.55% of dietary DM); and 4) diet containing equal blend (7.69% of dietary DM) of roasted- and extruded soybean. Feed intake, sorting index, meal pattern, and chewing behavior were measurement using standard procedures. Milk yield and milk composition, dry matter intake, meal size and inter-meal interval were not influenced by experimental diets. Although both meal length and total eating time tended (P=0.06) to be increased for primiparous vs. multiparous cows, eating rate (P=0.06) and dry matter intake (P=0.01) were greater for multiparous cows. Experimental diets had no effect on sorting index. Number of rumination bouts and total rumination time were greater for primiparous vs. multiparous cows. Results indicated that milk yield, dry matter intake, feeding pattern, and chewing activity were not influenced by feeding processed soybean instead of soybean meal.