Young Scholar Presentation: Making Something out of Nothing: The Potential of Calcium Hydroxide Treated Corn Stover for Dairy Cows

To provide food security as human demands for animal sourced foods increases with the rising global population, there is great need to improve the efficiency of livestock feed resources. Corn stover is an abundant crop residue typically left in the field and rarely used as a feedstuff for lactating dairy cows due to inherently low nutritional value. However, processing strategies, like those used in cellulosic ethanol production that enhance nutrient digestibility of corn stover may enable use in lactating dairy cow diets. Chemical pretreatment of corn stover with 6.6% calcium hydroxide (TCS) improves the digestibility of the corn stover by breaking the lignin barrier and increasing the digestibility of hemicellulose and cellulose. We hypothesized that TCS could replace a portion of traditional forages in diets fed to lactating dairy cows without negatively impacting milk production or milk composition. In Study 1, mid-lactation Holstein cows (n = 30) were assigned to either a control TMR (CON) or a TMR where TCS replaced alfalfa haylage (HYLGsub) or alfalfa haylage and a portion of the corn silage (HYLG+CSsub) at 15 or 30% of the diet DM, respectively. Dry matter intake was reduced (P < 0.05) when cows were fed the HYLGsub diet compared with CON fed cows. Milk production, milk composition, and 4% ECM was not different (P > 0.05) between cows fed the CON, HYLGsub, and HYLG+CSsub diets. Study 2 examined maximal replacement of alfalfa haylage and corn silage with TCS using CON and HYLGsub diets with maximal corn silage replacement at 19% of the diet DM (CSsub) using lactating Holstein cows (n = 6) in a 3 x 3 replicated Latin square. We confirmed that DMI is reduced with TCS inclusion (P < 0.05) but milk production and 4% ECM was not different among treatments (P > 0.05). Energy corrected milk per unit of DMI was greater (P < 0.05) for cows fed TCS even though apparent DM digestibility was reduced (P < 0.05) when cows were fed the CSsub diet indicating an improved efficiency of feed resources with TCS inclusion. Cost benefit analysis revealed that income over feed costs were improved with TCS inclusion. Taken together, these results demonstrate that TCS can serve as a valuable partial replacement for traditional forages while improving the efficiency of feed converted to milk. Feeding strategies incorporating TCS may allow efficient use of feed resources and help provide food security for the growing population.