Reviewed October 1993

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Contents

• How much WSB should I feed?
• How much fat can I allow?
• What if fat content is too high?
• WSB feeding studies

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Whole Soybeans for Dairy Cattle

Ron Belyea and Barry Steevens
Department of Animal Sciences

Whole soybeans (WSB) can be used in dairy cow rations; they are palatable and have excellent feed value. WSB have lower protein content than soybean meal, but because of higher fat, have higher net energy content (Table 1).

Table 1
Comparison of whole soybeans to soybean meal

	As fed basis
	WSB	Soybean meal
Protein, percent	39	44
ADF, percent	9	10
NDF, percent	10	12
Crude fiber, percent	6	6
Fat, percent	18	1.4
Ca, percent	0.28	0.36
P, percent	0.66	0.75
Net Energy Mcal per pound	0.88	0.79

How much WSB should I feed?

You can feed limited amounts of WSB. We generally consider the maximum to be six to seven pounds per day or up to 20 percent of the concentrate. The amount depends upon other feed ingredients in the ration and their fat content (Table 2).

Table 2
Fat content of feeds (dry basis)

Feeds	Percent fat
Barley	4.3
Corn	2.3
Whole cottonseed	25.0
Dried distiller grains	9.4
Hominy	8.3
Milo	3.2
Oats	4.4
Whole SB	20.0
SB meal	1.4
Wheat	2.0
Alfalfa hay	2.0
Corn silage	1.0

Some examples

Ration 1

• 20 pounds corn
• 7 pounds WSB

Ration 2

• 3 pounds whole cottonseed
• 20 pounds corn
• 5 WSB

Ration 3

• 10 pounds corn
• 10 pounds distillers grains
• 5 pounds WSB

Ration 4

• 25 pounds milo
• 7 pounds WSB

The point is that the other ingredients add fat to the diet and this must be taken into account. The more fat there is in the other grains, the less WSB you should feed.

How much fat can I allow?

Most research indicates that if the total diet contains more than about 5 percent fat, digestibility, milk yield and milk composition may decline. For the average cow eating 40 to 50 pounds of DM daily, 5 percent fat amounts to 2 to 2.5 pounds of fat (Table 2).

What if fat content is too high?

Too much fat may often depress digestibility, particularly that of fiber. This may be because fatty acids, hydrolyzed from fat in the rumen, attach to bacteria and inhibit their action. This effect, however, is minimized by increased calcium and magnesium in the diet.

In a study at Ohio State, researchers fed cows diets containing various proportions of corn, oats, wheat bran, soybean meal, alfalfa meal, corn silage and alfalfa pellets. Fat percent in the diet varied from 3.2 to 10.8 percent. The data are summarized in Table 3.

Table 3
Effect of feeding diets varying in fat percent (Ohio State study.)

Diet	Experiment 1			Experiment 2
	11	12	13	21	22
Protein, percent	16.6	17.5	17.5	15.9	16.3
ADF, percent	18.2	18.5	19.7	19.3	21.3
Fat, percent	3.2	5.7	10.8	2.9	6.8
Calcium, percent	0.7	0.8	0.8	0.6	6.8
Concentrate, percent diet	42	42	42	50	33
Digestibility, percent DM	62.5	67.3	66.7	63.1	59.3
Digestibility, percent ADF	35.6	44.3	44.0	31.3	35.3
Digestibility, percent protein	64.0	67.6	70.6	63.7	66.7
DMI pounds per day	44.4	46.6	40.4	42.5	44.4
FCM pounds per day	62.3	66.7	59.8	53.2	60.9
Milk fat, percent	3.51	3.42	3.25	2.71	3.44
Milk protein, percent	3.06	3.04	3.12	3.38	3.23

In this study, increasing dietary fat had little effect on intake. Milk yield (FCM) was highest for the 5.7 percent fat group; milk fat percent decreased as fat increased. Digestibility was increased in the 5.1 percent fat diet (Diet 12) but not in the 10.8 percent fat diet (Diet 13). Milk protein percent, sometimes depressed by high dietary fat, was unaffected in this study. Milk fat percent was lower in diet 21, probably because more concentrate was fed.

WSB feeding studies

WSB were fed to lactating cows in several studies. They are summarized in Tables 4 and 5.

Table 4
Feeding whole soybeans to dairy cows (Wisconsin-Marshfield study)

	Ensiled shelled corn + dry WSB	Ensiled ear corn + ensiled WSB	Dry conventional concentrate
Concentrate, pounds DM per day	9.8	11.0	9.2
Forage1, pounds DM per day	23.6	23.8	25.4
FCM, pounds per day	39.9	40.1	38.5
Milk fat, percent	4.11	4.16	4.23
Number of cows	17	17	17

¹Legume -- grass haylage and corn silage.

Table 5
Feeding whole soybeans to dairy cows (California study)

			Whole cotton seed
	Control	WSB	15 percent1	30 percent1
DMI, pounds per day	41.4	42.8	40.7	42.0
Test feed, pounds per day2	–	3.4	6.8	14.0
Milk, pounds per day	71	77	67	70
Milk fat, percent	3.7	3.74	4.0	4.18
Milk protein, percent	3.14	3.06	2.99	3.01

¹Percent of diet.
²WSB, 15 percent WCS or 30 percent WCS

These studies suggest that reasonable amounts of WSB don't cause detrimental effects and can be substituted in typical diets. Some other concerns and considerations are:

• WSB contain urease. If they are mixed with diets containing urea, ammonia will form, decreasing palatability.
• Calcium and magnesium concentrations should be higher than in conventional diets, because both form insoluble complexes with fat.
• WSB can be used beneficially in high-grain rations to reduce starch intake.
• Ensiling is a good method of storing and handling WSB, especially in a wet year. Preservatives (propionic acid) may be another option.
• WSB may be ground prior to feeding. Grinding appears to offer no nutritional advantage, but may improve handling characteristics. Ground WSB will become rancid if allowed to stand too long; don't process more than 10 day's worth at a time. Vitamins including vitamin E should be added.
• Balance diets carefully when using WSB to meet protein and energy requirements.
• Increased fat for high producers in early lactation may reduce the incidence of ketosis, because fat contributes energy directly to meet metabolic needs. Because fat is high in energy density (2.25 x carbohydrate), this contribution can be significant. Substituting one pound of fat for one pound of starch increases net energy by 1.3 Mcal per day.
• Blending WSB into a TMR along with forage and concentrates is a good feeding strategy.

G3270, reviewed October 1993