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Silage — the forage of choice for cattle feeders

Nutrition with John McKinnon, beef cattle nutritionist

This past winter has again demonstrated the value of cereal silage as a forage source for cattle feeders. Many of you will recall that hay supplies were tight last fall, particularly in Western Canada and as a result, for many feedlots hay was priced out of the ration. How did these lots make it through the winter without hay? To answer this question, you don’t have to look any further than the silage pile. Silage for many lots was the forage base of the feeding program. In fact, for many feeders, hay was restricted to the starter ration and even then, it was fed at levels that were approximately half of the normal inclusion rate.

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This reliance on silage is not restricted to western Canadian feedlots, nor is it restricted to drought years. Feeders across the country rely on silage year in and year out to provide both the quantity and quality of required forage at a competitive price. What is changing, however, is that cattle feeders have more choices with respect to forage crops and within crops, to specific varieties that can be grown for silage. With this article I will discuss some of these options, particularly with reference to barley, corn and triticale.

Let’s start with barley as it has traditionally been the crop of choice for silage in Western Canada. Barley is a relatively early-maturing cereal that grows well in most soil zones. There are a number of feed or semi-dwarf varieties that one can grow for silage depending on requirements for maturity, disease and lodging resistance and choice of smooth versus rough awns. With proper fertility and moisture conditions, barley will yield three to 3.5 tonnes of dry matter per acre; however, experience at the University of Saskatchewan has shown that yields can drop to two tonnes of dry matter under less-than-optimal conditions. To optimize both dry matter and nutrient yield, barley is typically harvested for silage at the mid- to late-dough stage. Barley cut at this stage will average 10 to 12 per cent protein and 63 to 65 per cent total digestible nutrients (TDN). Variety can influence both the yield and nutritive value of the resulting silage. For example, CDC Cowboy is known for its yield potential, however, relative to varieties such as Rosser, it has lower TDN levels due to higher fibre and lower starch content.

Corn has been a staple forage source for feedlots in Eastern and Central Canada for many years. The development of early-maturing corn varieties has recently allowed for silage and even grain production in areas of Western Canada. Corn is a warm-season crop that requires relatively higher growing temperatures and moisture conditions than cereals such as barley or triticale. Corn is typically harvested for silage in the “Dent” stage of development when it is between 60 and 70 per cent moisture (65 per cent is ideal). During this phase the kernels fill with starch in a characteristic fashion. As the liquid starch fills the kernel, it progressively “hardens” from the crown to the base of the kernel. The separation between hard and soft starch is known as the milk line and is used as an indicator of maturity of the plant. For example, it is common to hear terms such as one quarter, one-half and two-thirds milk line as it moves from the crown to the base. The “black layer” forms when the milk line reaches the tips of the kernels, indicating the plant is physiologically mature. While there is no substitute for knowledge of whole-plant moisture content, corn is often harvested for silage between one-half and two-thirds milk line development. Given the right combination of temperature, moisture and seed variety, corn will outyield other silage crops in terms of dry matter (i.e. typically five to six tonnes or more per acre) as well as in digestible nutrient (i.e. 67 to 72 per cent TDN, DM basis) content. These benefits help to offset its higher costs of production. Selection of a variety suitable for local growing conditions is critical to obtaining this advantage. One drawback to corn silage from a nutritional perspective is its lower protein content which averages eight to nine per cent.

Triticale is a cereal that is gaining more attention as a silage crop, particularly with the release of newer varieties. Triticale can be fall or spring seeded and harvested as silage or greenfeed. Other advantages include its drought tolerance and the fact that it does not turn as quickly in the field as it matures. Yield trials carried out in Alberta have shown that triticale will equal or outyield barley as a silage crop. Nutritionally there is not a great deal of difference between triticale and barley silage when both are harvested at the correct stage of maturity, although barley silage tends to be more digestible at advanced stages of maturity. There is also the perception real or not, that cattle do not consume triticale as readily as barley silage.

These advances in plant breeding and agronomy are rapidly expanding the options that beef producers have for growing silage. Making the right choice will influence not only the quantity and quality of your forage supply but also its cost.

About the author

Contributor

John McKinnon is a Professor Emeritus at the University of Saskatchewan and a consulting nutritionist who can be reached at [email protected].

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