Effect of High Concentrate Corn Stalk Particle Size on Physical State and Production Performance of Lactating Dairy Cows

In order to realize the application of corn stalk in cow feed, we designed experiments to explore the effect of a certain proportion of corn stalk on the performance of lactating dairy cows. 9 multiparous mid-lactating cows were allocated at random to three groups, each containing 3 intact cows. The trial consisted of three periods and three dietary treatments with a 3 × 3 Latin square design. The diets were normal concentrats plus dried corn stalk chopped to 5 - 8 cm long (N), high concentrates plus dried corn stalks chopped to a length of approximately 5 - 8 cm by a mower (H) while the milled corn stalks were passed through a pulviser with a 2 cm pore size (MH). Each cow was measured for dry matter intake (DMI), ruminal pH, rumen fermentation, selective feeding behavior and production performance. The results showed that MH led to a significantly higher intake of DM, neutral detergent fiber (NDF), forage NDF (FNDF), acid detergent fiber (ADF), crude protein (CP) and organic matter (OM) than N and H (P < 0.05). Cows fed H and MH showed similar selective feeding behavior, while those fed H showed various selectivity for the dietary component. MH resulted in a significantly higher milk production (P < 0.05), and tended to have a higher milk fat production than N (P = 0.055). There were no significant differences in the milk components (P = 0.424) and lactose (P = 0.113) between cows fed N and MH. The high-concentrates plus milled corn stalk diet can increase the milk yield under the premise of normal rumen pH in dairy cows, thereby generating higher economic benefits. And milled corn stalk can effectively inhibit the cow’s selective eating of low-quality roughage.