In early August of 1996, the FDA banned the use of meat and bone meal and bone meal products in ruminant rations. Because of the widespread use of meat and bone meal as an undegradable intake protein (UIP) source, alternative UIP sources need to be used. UIP bypasses rumen fermentation and is often referred to as bypass protein. Undegraded intake protein sources are supplemented in the ration to provide amino acids to the small intestine beyond what is supplied through normal rumen fermentation. Supplemental UIP is often required to support higher milk production (>70 lb).

    An essential amino acid (EAA) index will be referred to in this article. The EAA index is a measurement of the essential amino acids supplied by a feedstuff. A higher EAA index indicates more total essential amino acids are provided by the feedstuff. While a higher EAA index can indicate a higher quality UIP source, care must be taken when interpreting the EAA value. A lower EAA feedstuff may be a better source of UIP because it is providing an adequate level of the most limiting amino acid. UIP values in this article are expressed as a percent of the crude protein.
    Following is a review of some available feedstuffs with high UIP levels. While most feedstuffs have some UIP value, the feedstuffs considered here provide a minimum of 45% UIP.

Grain By-Products
Grain by-products most commonly used as UIP sources include:

• Dry Distillers Grains (DDG)

• Brewers grains (wet-WBG or dry-DBG)

• Corn gluten meal (CGM)

• Heat processed soybeans (HPS)w

Grain by-products tend to have lower protein levels and lower UIP levels as compared to animal proteins. However, grain by-products have a lower cost per ton and tend to be more palatable than animal proteins.

Dry Distillers Grains (DDG)
Dry distillers grains are derived from a number of grain sources, with the most common being corn. Distillers grains offer a very palatable source of UIP for dairy rations. The UIP of distillers is approximately 47% and the EAA index is 54 (see Table 1). A concern regarding the use of DDG is variable quality. Variation occurs from different sources of DDG and from within the same source. Distillers grains from corn are low in lysine; therefore, care must be taken to provide a UIP source high in lysine to balance the ration. This can present a problem in corn-based rations.

Brewers Grains
Brewers grains can either be wet (WBG) or dry (DBG), with the wet being more palatable but lower in UIP (50% versus 56%) than dry brewers. The EAA index of brewers grains is 67. Brewers grains are also limiting in lysine so care should be taken to provide a UIP source containing an adequate lysine level. Brewers grains tend to be high in fiber (bulky) and lower in energy, limiting their use for high-producing cows. Also, if the level is not closely monitored, WBG can increase the moisture level of the ration to the point of limiting dry matter intake and potentially causing foot problems.

Corn Gluten Meal (CGM)
Corn gluten meal is a UIP source used quite extensively in the Midwest because of its high protein and UIP level. Corn gluten meal is moderately palatable in dairy rations. The EAA index of CGM is 52. It is also lacking in lysine, so it should be used in combination with a UIP source that provides lysine. Care must be taken not to confuse corn gluten meal with corn gluten feed. Corn gluten feed is a low protein, highly soluble protein source.

Heat Processed Soybeans (HPS)
Whole soybeans can be heat processed in a number of ways including jet sploding, roasting, and extruding. Heat processing increases the soybean's UIP value. Depending on the process used, the UIP value of heat processed soybeans can be increased to 60%. The EAA index of HPS is 71. However, overheating soybeans can bind the protein, making it completely unavailable to the cow.

    Heat processed soybeans are very palatable and can easily be used in a top dress situation for high-producing cows. When using HPS, the fat level of the ration needs to be evaluated. Also, the UIP value of HPS is reduced if the soybean is finely ground. Since soybeans are lacking in methionine, a source of methionine should be fed when using HPS.

Animal By-Products
Animal by-products tend to have a high UIP value, but are more costly per ton than grain by-products. Also, they tend to be less palatable. Animal by-products may help reduce the ration cost per cow daily or positively affect income over feed cost. Animal by-products tend to have a better balance of EAA as compared to grain sources. The most common animal by-products used are:

• Feather meal

• Blood meal

• Fish meal.

Meat and bone meal from porcine sources is beginning to gain popularity; however, no appreciable amount of research with dairy cows has been conducted.

Feather Meal
Feather meal is produced through the steam hydrolysis of poultry feathers. It has been used in many dairy rations because of its high protein and high UIP levels, and comparatively lower cost as compared to other animal by-products. However, when compared to other animal proteins, the quality of the UIP is lacking. The EAA index of feather meal is only 34.

    Feather meal provides less methionine and lysine than other UIP sources listed in Table 2. Also, palatability and quality control concerns must be factored in the decision to use feather meal. Availability of amino acids are a major concern with the use of feather meal.

Blood Meal
Blood meal is a high protein, high UIP source. Blood meal provides high levels of lysine making it a good source of UIP in rations limiting in lysine. The EAA index of blood meal is 60. Blood meal should be limited to a maximum of one lb per head daily due to palatability concerns.

Fish Meal
Fish meal is a high protein, high UIP source. Fish meal provides a high level of both methionine and lysine making it an excellent UIP source. Palatability concerns limit the inclusion of fish meal in the ration to one lb per head daily. The EAA index of fish meal is 68.

Conclusion
When considering a UIP source, many factors need to be considered, one of which is the most limiting amino acid. In the Midwest, most dairy rations are limited in methionine and lysine. Table 2 compares the relative lysine and methionine (as a percent of total EAA) to most of the UIP sources discussed in this article.

    Another consideration when choosing a UIP source is relative cost. The inclusion of the UIP source in the ration should be profitable and increase income over feed cost by either increasing milk production or milk components. The inclusion of expensive animal proteins is probably only applicable for higher producing cows.

    Dairy producers should work closely with their nutrition advisor to balance the UIP fraction of the ration correctly. For most rations, multiple UIP sources should be considered to get the best balance of EAA.

 

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