- Jin Gan
Re-think Transition Cow Diet
There has been a lot of research being done on pre-fersh (dry cow) diets over the years. Controlling the energy consumption through the incorporation of low energy ingredients such as straw and low quality hay has been shown to improve transition cow health.
Overfeeding energy during dry period will cause lower performance in cows and higher incidences of metabolic disorders:
Lower fresh cow DMI and starts milk production at a later time.
Higher NEFA (non-esterified fatty acids) in blood and more triglyceride in the liver after calving.
There will be greater deposition of fat in the dry cow with overfeeding.
Decreased neutrophil function postpartum.
Ensuring a smooth transition from pre-fresh to post-fresh diet will improve DMI. What other strategies can be used to improve this? The dry cow ration and fresh cow ration are very different on paper but should "look" similar to the cows. Here are some way to accomplish that:
1) Reducing particle size of the dry cow TMR to the particle size of the lactating TMR
Use finely chopped straw (less than 1 inch) to create a non-sortable ration for the dry cow.
Use Penn State Forage Separator to evaluate.
The reduced particle size will increase passage rate through the cow's rumen. This will then lead to a higher DMI in the pre-fresh group.
Due to the higher DMI, more chopped straw should be added to control energy intake.
Higher DMI pre-calving will be closer to the expected DMI post calving.
This decreasing gap will help to improve the transition between the 2 diets.
Another way is to feed higher energy diet which will increase DMI pre-calving but this would also result in higher concentration of liver fat.
2) Feed similar ingredients during pre and post calving
Keeping total diet potassium (K) low (less than 1.2% of DMI) is crucial when incorporating haylage into the diet.
Using corn silage and chopped straw without haylage poses some issues with the diet.
If the target of 14% crude protein diet is not achieved, then additional purchased protein sources such as soymeal may need to be added.
Haylage is a good nutritional choice as compared to other silage.
3) Increase density (kg per cubic foot) of pre-fresh diet or lower the density of the fresh cow diet
The goal for a "seamless" transition would be to keep these densities closer together.
Adding water to pre fresh TMR will increase density and reduce sorting behaviour.
Adding chopped hay to the fresh cow TMR will lower density of the fresh cow TMR.
4) Ensure fermentability of the diet
Dairy cow's microbial population requires nitrogen and carbohydrates to fuel growth.
Hence, having a healthy and vibrant population at calving will improve the transition to the fresh cow diet.
One way to increase fermentability of the diet is adding fermentable carbohydrate sources such as beet pulp or soyhulls in the dry cow diet.
Adding urea as a fermentable nitrogen source also helps to control energy while trying to maintain appropriate protein levels in the diet.
5) Use ketogenic ingredients in fresh cow diet
Using ketogenic ingredients such as beet pulp, sugar or whey permeate in the fresh cow diet will improve the energy available for rumen papillae and encourage rumen microbial growth.
Ketogenic ingredients are ingredients that tend to shift ruminal VFA to increased levels of butyrate.
Butyrate is the primary VFA that supplies energy to the rumen and it is involved in the rumen papillae growth.
Butyrate is converted to BHA by the ruminal papillae for fuel.
Ruminally derived ketones do not cause any problem but hepatic derived ketones are indicative of a problem.