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Myth #3: Goldilocks Likes it Just Right and so Should Your Cows
From an energy perspective, providing the Goldilocks diet to cows ensures they are neither overfed nor underfed, but rather given just the right amount of nutrients. Extensive research has shown that managing energy intake during the dry period—rather than overfeeding energy—leads to lower blood NEFA and BHBA levels after calving, less fat accumulation in the liver, and fewer cases of displaced abomasums (Dann et al., 2005, 2006; Douglas et al., 2006; Grum et al., 1996; Janovick and Drackley, 2010; Janovick et al., 2011; Richards et al., 2011; Mann et al., 2015; Zenobi et al., 2018). These lower levels of NEFA, BHBA, and liver fat indicate reduced fat mobilization because feeding the cow "just right" alters their metabolism, making their tissues more insulin-sensitive. Insulin is a hormone that decreases fat mobilization. Given the enhanced metabolic profile and the reduced cost and complexity of feeding one diet throughout the dry period, Goldilocks diets have gained widespread adoption among dairy farmers. It seems like a win-win situation—why wouldn’t you want your cows to be fed just right?
[Video Embed: Dr. Ric Grummer Myth Series Myth #3]
Background:
Research over the last twenty years suggests that we no longer need to "steam up" cows by increasing grain feeding in the three weeks leading up to calving. This practice was mainly aimed at preparing the rumen and its microorganisms for the higher grain diets consumed post-calving. The newer studies were conducted using total mixed rations (TMR), unlike older research which focused on feeding concentrates separately from forage. With the introduction of TMR feeding, cows don't receive large doses of grain like they used to when concentrates were fed separately from forage. This largely explains why, in most situations, it's unnecessary to "steam up" cows. This shift has led to the idea that a single diet with consistent energy content can be fed throughout the dry period. Practically speaking, this was seen as a breakthrough because it meant reducing diet costs during the dry period and simplifying feeding protocols. Coinciding with this new knowledge, "controlled" energy diets were developed. Also known as "Goldilocks" diets, these are high in low-quality forage, usually straw, and are fed throughout the dry period. The aim is to meet but not exceed the cow's energy requirements when they consume the diet ad libitum.
Busting the Myth:
Figures 1, 2, and 3 each present ten treatment comparisons where controlled energy intake was compared to overfeeding energy. Energy intake was controlled by either feeding the Goldilocks diet and comparing it to a diet higher in energy density (both at ad libitum feed consumption) or by feeding a common moderate energy density diet at two different levels of intake. Typically, the treatment that overfed energy was targeted at 140-150% of the cow's energy requirement, while the controlled energy treatment was targeted at 80-100% of the requirement. Milk production responses varied, but some trials showed significant reductions in milk yield. Milk fat percentage was consistently lower, and measures of total energy output through milk, such as fat- or energy-corrected milk yield, were also often reduced. From a biological perspective, this data makes perfect sense. As discussed in previous myth-busting articles, NEFA and BHBA are energy sources and milk fat precursors for the mammary gland. Reducing fat mobilization and the availability of these compounds to the mammary gland would logically lead to some downstream effects on lactation performance.
*Figure 1
Differences in milk yield when controlling energy intake (usually 80-100% of energy requirements) vs overfeeding energy (usually 140% of energy requirements).
[Image: Differences in milk yield]
*Figure 2
Differences in milk fat percentage when controlling energy intake (usually 80-100% of energy requirements) vs overfeeding energy (usually 140% of energy requirements).
[Image: Differences in milk fat percentage]
*Figure 3
Differences in fat- or energy-corrected milk yield when controlling energy intake (usually 80-100% of energy requirements) vs overfeeding energy (usually 140% of energy requirements).
[Image: Differences in fat- or energy-corrected milk yield]
Take Home Message:
The goal is to strike a balance: provide enough NEFA to the mammary gland to support lactation without subjecting the cow to negative effects that might arise from excessive NEFA mobilization. The reasons for the inconsistent effects when feeding controlled energy diets remain unclear, and further research is needed to shed light on them. The takeaway isn't to avoid Goldilocks diets. Dairy producers may be able to achieve both improved health and no reduction in milk yield. However, they should also recognize that not everything may be "just right" when feeding Goldilocks diets. Unfortunately, very little research has been conducted to determine the optimal energy intake levels between 100% and 150% to find the best feeding level for dry cows. Remember that when formulating diets, energy density values of diets are merely estimates! Be mindful that feeding to 100% of energy requirements (on paper) might be slightly too low.
Sources:
DANN, H. M., D. E. MORIN, G. A. BOLLERO, M. R. MURPHY, AND J. K. DRACKLEY. 2005. Prepartum intake, postpartum induction of ketosis, and periparturient disorders affect the metabolic status of dairy cows. J. Dairy Sci. 88:3249-3264.
DANN, H. M., N. B. LITHERLAND, J. P. UNDERWOOD, M. BIONAZ, A. D. ANGELO, J. W. MCFADDEN, AND J. K. DRACKLEY. 2006. Diets during the far-off and close-up periods affect periparturient metabolism and lactation in multiparous cows. J. Dairy Sci. 89:3563-3577.
DOUGLAS, G. N., T. R. OVERTON, H. G. BATEMAN, H. M. DANN, AND J. K. DRACKLEY. 2006. Prepartal plane of nutrition, regardless of dietary energy source, affects periparturient metabolism and dry matter intake in Holstein Cows. J. Dairy Sci. 89:2141-2157.
GRUM, D. E., J. K. DRACKLEY, R. S YOUNKER, D. W. LACOUNT, AND J. J. VEENHUIZEN. 1996. Nutrition during the dry period and hepatic lipid metabolism of periparturient dairy cows. J. Dairy Sci. 79:1850-1864.
JANOVICK, N. A., AND J. K. DRACKLEY. 2010. Prepartum dietary management of energy intake affects postpartum intake and lactation performance by primiparous and multiparous Holstein cows. J. Dairy Sci. 93:3086-3102.
MANN, S., F. A., LEAL YEPES, T. R. OVERTON, J. J. WAKSHLAG, L. LOCK, C. M. RYAN, AND D. V. NYDAM. 2015. Dry period plane of energy: Effects on feed intake, energy balance, milk production, and composition in transition dairy cows. J. Dairy Sci. 98:3366-3382.
RICHARDS, B. F. 2011. Strategies to Decrease Fatty Liver in Dairy Cows. PhD Thesis. University of Illinois, Urbana-Champaign.
SILVA-DEL-RIO, N., P. M. FRICKE, AND R. R. GRUMMER. 2010. Effects of twin pregnancy and dry period feeding strategy on milk production, energy balance, and metabolic Anim. Sci. 88:1048-1060.
ZENOBI, M. G., R. GARDINAL, J. E. ZUNIGA, A. L. G. DIAS, D. NELSON, J. P. DRIVER, B. A. BARTON, J. E. P. SANTOS, AND C. R. STAPLES. 2018. Effects of supplementation with ruminally protected choline on Performance of multiparous Holstein cows did not depend upon prepartum caloric intake. J. Dairy Sci. 101:1088-1327.
Related Posts:
Myth #6: If You Are Feeding Rumen-Protected Methionine You do Not Have to Feed Rumen-Protected Choline
Myth #5: If You Are Feeding Goldilocks Diets, You do Not Have to Feed Rument-Protected Choline