Feeding Dry Cows A Single TMR Could Be Enough
Pennsylvania State University researchers have been examining the traditional approach of feeding dry cows in two separate groups. Their findings suggest that if a two-group approach isn't working on your farm, feeding dry cows a single total mixed ration (TMR) could be beneficial.
Dry cows are usually split into two groups: far off and close up. The two groups are separated because it has been thought that dry cows need to rest their rumen, can be fed cheaply and need less management. Close-up cow diets start three weeks before calving and are designed to prepare the rumen for the milking diet.
Penn State professor Gabriella Varga and her research group question the benefit of the traditional two-group approach from a nutritional and metabolic standpoint. Many producers are already successfully feeding a single dry cow TMR. The researchers examined the benefits and drawbacks of this strategy.
The single dry cow TMR strategy works by keeping the cow primed for lactation. Far-off cows fed a high-forage diet can lose almost 50 per cent of their capacity to absorb volatile fatty acids (VFA). Restoring this capacity can take five weeks on a higher concentrate diet. Absorbtion of VFA is important because they're required to make glucose in the liver and milk fat in the mammary glands. Corn silage, popular in dry cow diets, decreases the decline in VFA absorbtion. Penn State's approach keeps the cow ready for the milking diet.
Varga notes that critical changes to liver and gut functioning can take five weeks. Three-week close-up diets can leave necessary changes incomplete. A one-group TMR reduces nutritional changes when switching to the milking diet.
Since this nutritional strategy improves pre-calving dry matter intake, it can significantly reduce metabolic disorders like ketosis. Improved cow health during the transition phase can increase peak milk yield. Reduced veterinary costs for treating metabolic disorders and higher milk production more than offset the increased cost of a single dry cow ration.
A key component of the one-ration approach is replacing a portion of the ration's forage component with non-forage fibre sources (NFFS). Avoiding rumen-fill from feeding low-quality forages is important. Examples of NFFS are soy hulls, cottonseed hulls and corn cobs. These ingredients provide necessary fibre in the diet, but they're digested faster and don't contribute to rumen fill as much as forage fibre.
Research trials have shown that there is no impact on milk production when a restricted amount of feed is offered in the dry period, as long as the ration is formulated and mixed properly. The benefit of higher dry matter intake in the dry period is reduced incidence of metabolic problems. The studies with NFFS sources have increased dry cow dry matter intake by about three kg per day compared to traditional dry cow feeding.
The Penn State research has shown that a single dry cow TMR can be fed without adding excess body condition.
If your current dry cow system is working well, it's probably good to leave well enough alone. If you are spending a lot of time and money addressing transition cow and metabolic problems, a single dry cow TMR is worth discussing with your herd management team.
Advantages of different dry cow nutritional systems (adapted from Varga, 2003)
Single dry cow ration:
Early and close-up rations:
Ontario Milk Producer, May 2003.
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