Assessment of feeding high moisture corn grain with different qualities of alfalfa hay in high-forage lactation dairy diets
This experiment was performed to test a hypothesis that quality of alfalfa hay (AH) would affect nutritive benefits of feeding high moisture corn (HMC) due to their associative effects on nutrient utilization efficiency. Eight multiparous lactating Holstein cows were used; 4 were surgically fitted with ruminal cannula. Days-in-milk averaged 184 ± 10.7 at the start of the experiment. The experiment was performed in a duplicate 4 × 4 Latin square design. Within each square, cows were randomly assigned to a sequence of 4 diets during each of the four 21-d periods (14 d of treatment adaptation and 7 d of data collection and sampling). A 2 × 2 factorial arrangement was used; fair quality AH (FAH; 39.6% NDF and 17.9% CP) or high quality AH (HAH; 33.6% NDF and 21.9% CP) was combined with steam-flaked corn (SFC) or HMC to form 4 treatments: FAH with SFC, FAH with HMC, HAH with SFC, and HAH with HMC. The AH was fed at 32% DM, whereas HMC was included at 17% DM. Quality of AH did not affect DMI, whereas feeding HMC decreased DMI (P = 0.04) regardless of quality of AH. While digestibility of DM increased by cows fed with HAH compared to those fed with FAH (70.1 vs. 67.6%; P = 0.05), NDF digestibility increased by feeding HMC (67.6 vs. 58.4%; P = 0.03) but not quality of AH. Starch digestibility decreased by feeding HMC with FAH (85.7 vs. 95.0%) but not with HAH, resulting an interaction between quality of AH and type of corn grain (CG; P = 0.02). Feeding different qualities of AH did not affect milk yield; however, feeding HMC numerically decreased milk yield in FAH diet, but increased milk yield in HAH (30.4 vs. 29.6 kg/d), causing an AH × CG interaction (P = 0.05). Efficiency of milk yield/DMI was improved due to feeding HMC regardless of quality of AH (P = 0.05). In addition, dietary N utilization for milk N tended to increase by feeding HMC (P= 0.07), but it was not influenced by quality of AH. Overall results in this experiment indicate that feeding HMC in high-forage diets improved feed efficiency as well as N utilization efficiency regardless of quality of AH.
Keywords: alfalfa hay, feed efficiency, high moisture corn