"Goldilocks" Diet Still Just Right for Dry Cows
When it comes to feeding dry cows, several different strategies have been tried over the years. But during the last 10 years, controlled-energy diets, also called the “Goldilocks” diet, have proven to deliver consistent and beneficial results.
When University of Illinois researchers first reported the benefits of feeding a controlled-energy diet to dry cows, it was met with a great deal of skepticism, says James Drackley, professor of dairy nutrition at the University of Illinois. Today, dry cows around the world are fed controlled-energy diets with considerable success.
"The foundation of this approach is that dry cows and close-up cows should be fed to meet their requirements for energy, without underfeeding or allowing cows to consume an excess of energy. By using bulky, low-energy forages to dilute higher energy corn silage, cows can still consume feed ad libitum and eat to a maximum as defined by rumen fill,” explains Drackley. Research has shown that when dry cows and close-up cows overconsume energy, it is counterproductive to trouble-free transitions.
The simplest and most easily defended principle of nutrition for dry cows is to feed to meet, but not greatly exceed, NRC requirements (Drackley and Dann 2008). Numerous research trials have demonstrated that feeding dry cows a controlled-energy diet leads to better transition outcomes.
In contrast, cows fed a moderate-energy diet (1.50 to 1.60 Mcal NEL/kg of DM) consume about 40 to 80% more energy than required (Dann et al., 2005, 2006; Douglas et al., 2006; Janovick and Drackley, 2010). No evidence indicates that extra energy intake during the dry period is beneficial in any way, says Drackley. Instead, negative results have been observed. Lower dry matter intakes after calving, slower starts in milk production, higher levels of non-esterified fatty acids (NEFA) in blood and higher levels of triglycerides in the liver after calving are all negative impacts that can occur when dry cows are overfed energy.
When cows consume more energy than needed it must be dissipated as heat or stored as fat. Illinois research shows that while cows that were moderately overfed energy may not become noticeably over-conditioned, they often encounter the same health problems as overly fat cows.
In addition, cows moderately overfed energy deposit more of that fat in their belly area (Drackley et al., 2014). This visceral adipose tissue releases NEFA and signaling molecules that go directly to the liver (Ji et al., 2014). This in turn may cause fatty liver, subclinical ketosis and other secondary problems with liver function. “The mechanisms we have been studying in dry cows are similar to the mechanisms for disease in humans which leads to obesity, type II diabetes and insulin resistance,” explains Drackley.
Benefits of the Goldilocks Diet
Formulate controlled-energy diets to deliver 1.30 to 1.38 Mcal NEL/kg DM. Rations that are low-energy, high fiber allow cows to eat to their fill without greatly exceeding their energy requirements. Research at Illinois combined with observations in the field show that feeding low-energy, high-bulk total mixed rations to dry cows can virtually eliminate the occurrence of displaced abomasums and provide a marked reduction in BHBA concentrations during the early postpartum period. In addition, field survey data from 27,000 cows in the United Kingdom, Ireland, France and Sweden showed dry cows fed a controlled-energy diet had fewer assisted calvings and had decreased incidence of milk fevers, retained placentas, displaced abomasums and ketosis (Colman et al., 2011). Their results also showed improved reproductive performance.
While the data is limited, it appears that milk production for cows fed controlled-energy diets is similar to dry cows fed higher-energy close-up diets. Field results from producers indicate that cows fed controlled-energy diets may have greater lactation persistency, but slightly lower peaks. So when evaluating a change to dry cow rations, look at total lactation milk yield, daily milk and persistency of lactation, not just peak milk.
Reproduction is another area where controlled-energy diets provide benefits. Research by Cardoso et al., 2013; showed that overfeeding energy during late pregnancy does not improve milk production, increases the risk of metabolic disorders and hinders reproductive success.
Another benefit of controlled-energy diets is that dry matter intakes remain more constant as cows approach calving, and producers who prefer to use far off and close-up groups can feed essentially the same diet. If producers feed a negative dietary cation anion difference (DCAD) diet to close-up cows, all they have to do is add their chosen anionic product. And for dairies that utilize a shorter dry period or are smaller in size, one dry cow diet works well.
Getting It Right
The optimal high-forage, low-energy dry cow diet should contain the primary forages fed in the lactation diet, but be diluted with straw or low-quality forage to achieve a lower energy density. This helps the rumen remain adapted to the types of ingredients that will be fed after calving but without the extra energy.
Controlled-energy rations generally contain roughly one-third of the dry matter (DM) as corn silage, one-third as chopped straw (wheat straw is preferred) and the remaining third split between some other hay or silage and a small amount of concentrate to meet protein, mineral and vitamin requirements. The NEL requirement for a 1,500 lb. Holstein dry cow is between 14.5 and 15 Mcals per day (NRC 2001). The following are suggested guidelines for formulating controlled-energy diets for your dairy.
- DMI – 26.5 to 27.5 lbs./day.
- Energy Density – 1.30 to 1.38 Mcal NEL/kg DM.
- Protein – 12 to 15% of DM as crude protein or >1,000 grams/day of metabolizable protein as predicted by NRC (2001) model or CNCPS Dairy Model. This generally requires addition of high RUP sources such as heat-treated soybean meal or blood meal.
- Amino Acids – Supplement with a lysine:methionine ratio of <3.1. Use rumen protected methionine.
- Starch – 12 to 16% of DM. If starch is poorly fermentable use the upper end of the range.
- Forage NDF – 40 to 50% of total DM, or 10 to 12 lbs./day (0.7 to 0.8% of body weight).
- Total Ration DM – 45 to 48% (add water if necessary to achieve).
- Vitamins and Minerals – Follow standard NRC guidelines.
- Rumensin – Include in the ration at 300 mg/d to help increase milk production.
Controlling energy intake is exciting for its potential to markedly improve health during the transition period, says Drackley. Provided that high-bulk, low-energy rations are formulated, mixed and delivered properly, results have been positive and consistent.