This answer was part of a presentation at the recent Cornell Nutrition Conference by Tom Overton and Daryl Nydam, of Cornell University.
Q: How has nutritional management of dry cows evolved over the past five to seven years?
A: Recommendations for nutritional management of cows during the dry period have evolved substantially during the past five to seven years. The industry has largely abandoned the “steam-up” concept with higher-energy diets fed to dry cows during the close-up period, as advocated by the authors of the 2001 Dairy NRC, in favor of controlled-energy strategies for dry cows during both the far-off and close-up periods (Drackey, 2007). Furthermore, controlled-energy strategies have lent themselves toward more widespread adoption of low-energy, one-group dry cow programs.
Drackley (2007) has advocated diets for both far-off and one-group dry cow programs with the following specifications (0.59 to 0.63 Mcal of NEL/lb of DM; 12 to 16 percent starch, and 40 to 50 percent forage NDF in the total diet). While we believe that energy and nutrient densities in these ranges are appropriate for cows during the far-off period and cows during the close-up period, they may be too low in many cases if these diets are fed to heifers during the prepartum period, especially in co-mingled scenarios with varying stocking densities.
Goals for NEL intake of both heifers and cows during the far-off and close-up periods range from 15 to 18 Mcal/day. For most prepartum heifers, this likely means energy densities in the vicinity of 0.66 Mcal/lb, so a reasonable compromise would be 0.64 to 0.66 Mcal/lb if the same diet is fed to both cows and heifers during the prepartum period. Of course, actual energy densities of diets should be based upon actual farm DMI to achieve the energy intake targets specified above.
Limited research has focused on relationships between nutritional management during the far-off and close-up periods with consideration to one-group approaches to dry cow nutritional management. Dann et al. (2006) fed diets during the far-off period to achieve 80 (actual 77), 100 (actual 95), or 150 (actual 160) percent of NRC-predicted energy requirements followed by a close-up diet fed either above energy requirements (average 135 percent) or restricted to below energy requirements (80 percent). Surprisingly, close-up feeding strategy did not affect periparturient metabolism or performance. Cows overfed during the far-off period had lower subsequent DMI and calculated energy balance along with elevated BHB and NEFA during the first 10 days postpartum.
Richards et al. (2009) recently compared a controlled-energy (~0.60 Mcal/lb NEL) feeding strategy with a high-energy diet (~0.73 Mcal/lb NEL) fed for the entire dry period and a two-group feeding strategy in which cows were fed the controlled-energy diet during the far-off period and the high-energy diet during the close-up period. As expected, the cows fed the high-energy diet during the entire dry period gained more body condition during the dry period and lost more body condition during the postpartum period. Cows fed the controlled-energy diet had lower postpartum NEFA, BHB, and liver fat compared to cows fed the high-energy diet. Metabolic health parameters for cows fed the two-group strategy were more similar to the controlled-energy one-group diet than the high-energy diet.
Collectively, these data continue to support the concept of moderating energy intake during the entire dry period, regardless of specific dietary grouping strategy. One-group dry period diets can provide additional flexibility for farms to vary their times in close-up groups to manage stocking density or other factors without concern for nutritional support. We advocate that strategies for macromineral formulation of one-group dry cow diets mirror that used for close-up diets, as prevention of hypocalcemia and related disorders is a critical part of nutritional management during the prepartum period.