Use of By-Products in Lactating Dairy Cow Diets

Use of By-Products in Lactating Dairy Cow Diets

Adapted by Alejandro R Castillo, UCCE Merced County, California.

The drought in the Midwest will impact corn production and commodities prices. By-products can be used as an alternative feed to replace some of the feed ingredients normally used in dairy diets. A California survey⁽¹⁾ indicates that the three main feed ingredients used in lactating dairy total mixed rations (TMR) are corn silage (74% of rations), alfalfa hay (98% of rations), and corn grain (84% of rations), with many by-products also used to feed lactating cows (Table 1).

Table 1.  Estimated dry matter intakes of by-products and % of TMR including these by-products.

*TMR= percentage of TMRs including each byproduct (n=104 TMR)

The main nutritional concerns of using by-products are:

1. Possible mycotoxin contamination, particularly in fermented feeds (e.g. distillers grains) and feeds not stored properly.
2. Mineral content of some feeds may be very high (corn gluten, distillers grains, etc).
3. Excess dietary fat content: more than 7% dietary fat can affect production (i.e. cotton seeds, distillers grains, etc.).
4. High moisture level feeds increase transportation costs, are easily fermented (mycotoxins), create for difficult handling and storage, and can attract insects.
5. Excess or deficit of fiber (NDF): lack of fiber in the ration can be related to rumen acidosis problems (starch, molasses, whey, permeate, etc.) and excess fiber affects milk production (straw, raisin tailings, wheat bran, etc).
6. Palatability: some are relatively unpalatable (blood by-products) or they may be fermented affecting palatability (mycotoxins).
7. Crude protein content: can be very variable in some by-products affecting milk yield, feed efficiency, manure nitrogen content and nutrient management plans.
8. Animal performance: because of some of the points previously discussed, long-term use of by-products may affect animal performance, thus diets and feed management practices should be carefully controlled.

To save money and avoid problems with by-products in your TMR, consult your nutritionist before purchasing any new by-product and obtain a complete chemical analysis (including all minerals) to help reduce or mitigate some of the challenges discussed in this article.

(1) Access the TMR survey presented at the 2012 American Dairy Science Association meeting: http://cemerced.ucdavis.edu/Dairy/Recent_Dairy_Articles,_Posters_and_Presentations/