Soybeans staple nutrient source in dairy lactation diets

A handful of Manitoba farmers grew about 50,000 acres of soybeans in 2001.

After that, our soybean acreage steadily skyrocketed, and in the spring of 2025, nearly 1.6 million acres covered our beautiful province.

As a dairy nutritionist, I am a big fan of adding soybean meal (expelled-solvent extracted to remove its 20 per cent fat/oil content) into dairy diets for high-milk producing dairy cows.

In itself, common soybean meal has a lot going for itself:

• High quality and consistent feed source.
• Good dairy cow palatability.
• Crude protein content of 46 to 48 per cent, compared to 35 per cent for canola meal and 28 per cent for distillers dried grains.
• Bypass protein content of 35 per cent of exceptional essential amino-acid values.
• High dietary energy of 1.90 Mcal/kg.

My soybean-containing lactation diets are practical and designed to promote good dry matter intake among early to mid-lactation dairy cows (60 to 150 DIM), which produce 40 kilogram milk, 4.30 per cent milk fat and 3.3 per cent protein.

I do this soy exercise by relying upon a foundation of high-quality forages formulated with protein concentrates (including soybean meal), plus grains and grain byproducts.

A dairy premix is also added, containing essential minerals and vitamins. Limited-fed palm fat and feed additives are formulated in the final dairy mix.

In this illustrated case, it costs three pennies under $10 per day to feed a mid-lactating dairy cow.

This is a common way to express feed costs, yet there are other ways.

For example: $5.78 per kg of milk fat, $11.28 per cwt. of milk produced or $ 0.43 per kg of dairy diet consumed (dm, basis).

Regardless, all of the above costs of feeding a cow are bunk-feed numbers.

So far, I did not account for storage and mixing losses as well as any feed refusal by the lactating dairy cows.

I conservatively estimate these numbers at 15.0 per cent and two per cent, respectively. So, our raw feed cost of $10 per cow might be closer to $12 per cow, despite some salvageable value of feed refusal.

Again, soybean meal is a great source of dairy nutrients in the above diet, but I did not ignore the economic value of canola meal and distillers grains, which are suitable soybean meal replacements.

A practical comparison for these common feedstuffs upon a protein and bypass protein basis is as follows (commodity prices quoted are for demonstration purposes only):

Soybean ml protein (48% CP) = $470 mt/.48 = $980 mt vs. canola ml (36% CP) = $325/.36 = $ 903/mt

Soybean ml protein (48% CP) = $450 mt/.48 = $ 980 mt vs. distillers grain (28% CP) = $270/.28 = $965/mt

Soybean ml RUP protein (35% of CP) = $470 mt/.48/.35 = $ 2,798/mt vs. canola ml RUP = $350/.36/.44 = $2051/mt vs Distiller’s grain RUP (60% of CP) = $270/.28/.60 = $ 1,577/mt.

Canola meal placed second in this economic dairy-race based upon RUP. This is largely due to its precipitous drop to $325/mt in the last year or so.

In the same time frame; the value of soybean meal dropped 25 per cent from about $600/mt to its current post of $450/mt. The funny thing, if I simply removed the 0.5 kg per head of soybean meal in the above lactation diet, and replaced it with a protein-equivalent 0.7 kg of canola meal, there is no savings in feed costs.

Regardless, there is lots of Canadian dairy research that has replaced soybean meal with canola meal (based upon its widespread availability and a combination of its protein and RUP values) in lactation diets, and as a result, without any loss of milk production.

However, I have seen, on my own, some well-managed high milking dairy herds failing to achieve early lactation peaks due to the sole use of canola meal, which was later alleviated with a partial-substitution of soybean meal.

In a similar manner, I employ soybean meal as my staple source of many essential nutrients, which is more often than not complemented with canola meal and/or distillers dried grains.

As a result, the lactating dairy cows can consume the essential nutrients of all three feedstuffs without knowing it and produce high levels of milk/milk fat/milk protein.

Peter Vitti is an independent livestock nutritionist and consultant based in Winnipeg. To reach him call 204-254-7491 or email vitti@mymts.net.