The challenges and rewards of feeding by-products


Feeding dairy cows with by-products from production, post-harvest and food processing and other agro-industrial products has been common practice for decades. By-products streamline diet formulation and make up, on average, 30% of Midwestern dairy diets.

But this practice has been of the utmost importance to dairy farms in recent years. In addition to providing options for adjusting feed nutrients, feeding byproducts reduces feed costs and makes it easier to navigate low forage stocks.

Forage shortage

Corn gluten, brewer’s grains, whole cottonseeds, wheat scraps and straws, cottonseeds and soybean hulls are a few examples of options for expanding forage stocks when harsh weather conditions take a toll. for optimal forage production, harvesting and storage. These byproducts contain considerable amounts of NDF and help meet the fiber requirements of dairy cows.

But depending on their physical form, these foods may lack physically effective fiber. Physically effective fibers stimulate chewing and salivation, rumination, intestinal motility and health, and form the structural basis of the ruminal mat. If the fiber efficiency is too low, it is advisable to adjust the amounts of rapidly fermentable carbohydrates fed to reduce potential rumen health problems and milk fat depression.

Reduce feed costs

Reducing feed costs is the most common reason for feeding byproducts. Nutritional estimates from a survey of dairy nutritionists suggest that byproducts provide, on average, 44 percent of the crude protein and 33 percent of the energy of Midwestern diets. But these numbers increase in times when the prices of corn or protein sources are high.

However, power cost savings cannot come at the expense of performance. Dairy cows often maintain production by increasing their dry matter intake when fed a corn substitute by-product. Income versus feed costs is a better measure than feed cost alone because it takes these effects into account.

It is suggested to estimate the equilibrium costs to determine which by-products make sense of purchase. These estimates are based on the nutrient concentration. Several tools are available at no cost, including the University of Wisconsin FEEDVAL which compares the nutrient costs of byproducts with other animal feeds.

Face the challenges

Managing nutrient storage and variability issues associated with feeding by-products is critical. Wet by-products, such as wet brewers and distillers’ grains, have a shorter shelf life. These wet loads are particularly unstable when exposed to oxygen and degrade rapidly. Withdrawal losses of up to 30% can occur.

Receiving loads of these moist foods daily or several times a week circumvents this problem but increases transportation costs and nutrient variability.

Even though some by-products have been widely used for many years, it is advisable to monitor the quality and consistency of these foods so that the nutrients are properly adjusted in the diet. This is due to the great variation in raw materials and processing methods applied by different sources.

Using animal feed libraries as a starting point is acceptable as long as efforts are made to analyze nutrient composition. It is advisable to check food by-products from industries unrelated to human consumption for mycotoxins.

Changing diets, feed management and storage facilities for by-products that are irregular or seasonal in availability may not be justifiable due to additional time, management and storage requirements.

The logistics of storing by-products must be taken into account. While some by-products can be stored in feed bins, others may require pits or a large space in a product shed.

Environmental benefits

Feeding dairy cows with by-products enables the conversion of human inedible sources into high quality human edible proteins, such as milk. Otherwise, these by-products of food production, post-harvest and processing and other agro-industrial products would be composted, used for energy production, or landfilled or by incineration.

Compared to composting and landfilling, research has estimated that feeding dairy cows with by-products reduces greenhouse gas emissions five and fifty times, respectively.

Luiz Ferraretto

Luiz Ferraretto is a ruminant nutritional extension specialist at the University of Wisconsin – Madison



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