Introduction
The webinar begins with an introduction to Dr. Mike VandeHaar, a distinguished professor of dairy nutrition at Michigan State University. Dr. VandeHaar outlines his expertise in feed efficiency, energy metabolism, and sustainable feeding practices. He introduces the topic by explaining his interest in a study on short stature corn hybrids, prompted by discussions with agronomists from DeKalb, with the primary goal of determining if short corn is a cost-effective and beneficial alternative for dairy cattle silage.
Main Topics
Dr. VandeHaar establishes the foundational importance of feed efficiency in dairy production, emphasizing that higher milk production dilutes the maintenance energy cost per unit of milk. He discusses the critical balance between fiber (for rumen health) and starch (for energy), noting that highly digestible fiber allows for greater feed intake and milk production. He details feeding strategies across the lactation cycle, aiming for minimal fiber and high starch during peak lactation to maximize intake, and lower starch in late lactation to manage body condition.
The presentation details two studies conducted at MSU:
Study 1: This study compared five corn silage hybrids: three short corn varieties from Bayer, one conventional tall corn (DeKalb), and one BMR corn (Pioneer) as a positive control. The goal was to identify the superior short corn hybrid. The results showed that, on average, the short hybrids increased intake and energy-corrected milk production relative to the tall corn. One specific hybrid, ‘Short 1’, demonstrated the best performance in terms of both milk production and agronomic yield.
Study 2: This study focused on a direct comparison between the top-performing ‘Short 1’ hybrid and the conventional tall hybrid. Cows in peak lactation were fed one of four diets in a 2×2 factorial design: high vs. low starch, using either the short or tall corn silage. The key finding was that cows fed the short corn silage produced significantly more energy-corrected milk across both high and low starch diets. Notably, in the high-forage, low-starch diet, cows on the short corn silage had significantly higher feed intake, demonstrating the benefit of its superior fiber digestibility when gut fill is a limiting factor.
Key Insights Superior Digestibility: The short corn hybrid (‘Short 1’) showed higher in vitro NDF digestibility compared to the conventional tall hybrid and was intermediate between the tall and BMR hybrids.
Increased Milk Production: In Study 2, feeding the short corn hybrid resulted in approximately 4% more energy-corrected milk (about 4 pounds/day) compared to the tall hybrid, regardless of the starch level in the diet.
Higher Intake in High-Forage Diets: The advantage of the short corn was most pronounced in low-starch, high-forage diets, where its greater digestibility allowed cows to overcome limitations from rumen fill and consume more feed.
Agronomic Performance: In this specific trial, the ‘Short 1’ hybrid had a slightly higher tonnage yield per acre than the conventional tall hybrid, making it an economically attractive option.
Q&A Session:
Dr. VandeHaar addressed several questions from the audience, clarifying points on:
Energy-Corrected Milk (ECM): He explained his use of 0.7 ECM, which calculates milk energy directly rather than using traditional formulas.
Starch Differences: He acknowledged that diet formulation differences (e.g., adding more dry corn to balance starch) could be a factor but argued that the large differences in milk production were more likely due to the hybrid’s fiber characteristics than starch fermentation rates.
Parity Effects: There were no significant interactions between parity and diet; first-lactation and mature cows responded similarly.
Practical Application: He advised farmers interested in trying short corn to consider yield potential and test for forage NDF digestibility, as no single hybrid is perfect for every farm system.
Conclusion:
Dr. VandeHaar concludes that, based on his research, the tested short stature corn hybrid is a high-performing forage for cows in peak lactation, outperforming the conventional tall control. He emphasizes that the ideal corn silage depends on farm-specific factors like available land, other feed sources, and environmental conditions (e.g., wind). However, the study provides strong evidence that short corn hybrids with high NDF digestibility are a valuable tool for maximizing milk production and feed efficiency in dairy herds.
