Evaluating dairy ration proteins: When do they pay?

When choosing protein ingredients to include in the diet of lactating dairy cows, the true value of the ingredient needs to be determined.

SPONSORED BY CANOLA COUNCIL OF CANADA

By BRITTANY DYCK and ESSI EVANS*

*Brittany Dyck is with Canola Council of Canada in Winnipeg, Man. Essi Evans is with Technical Advisory Services Inc. in Bowmanville, Ont.

When determining which protein ingredients are the most economical to include in the diet of lactating dairy cows, it is easy to quickly make decisions based solely on the price of protein.

But what about the true value of the protein ingredient? Or to what extent does that protein ingredient result in production advantages, and do those production advantages outweigh the higher cost of an ingredient?

A study conducted at the University of Saskatchewan by Dr. Tim Mutsvangwa compared the feeding value of wheat distillers dried grains with solubles (W-DDGS) with canola meal at two levels of dietary protein. The preliminary results provided in Table 1 show that milk, fat and protein yield were all higher for cows fed canola meal at both levels of protein. The higher-protein diets also resulted in increased milk production.

1. Results of a study comparing canola meal and W-DDGS

 

-15% Crude Protein diet-

-17% Crude Protein diet-

 

Canola Meal

W-DDGS

Canola Meal

W-DDGS

DM intake, lb./day

69.0

69.6

68.1

69.4

Milk yield, lb./day

95.2

92.8

97.2

95.0

Fat, %

3.53

3.51

3.48

3.41

Fat yield, lb./day

3.33

3.24

3.31

3.26

Protein, %

3.22

3.25

3.26

3.23

Protein yield, lb./day

3.06

3.00

3.13

3.06

Milk urea-nitrogen, mg/dL

14.6

15.2

20.3

19.0

Feed efficiency, milk/DMI

1.38

1.33

1.42

1.37

At the time the study was conducted, the local price of W-DDGS was $260/metric ton, as compared to $360/mt for canola meal. The two products used in the study were characterized by researchers at Agriculture & Agri-Food Canada (Maxin et al., 2013; J. Dairy Sci. 96:5151-5160) before the trial commenced. Table 2 shows the nutrient makeup of the two protein sources.

2. Analyzed nutrient values for the two protein sources used in the study

Nutrient, DM basis

Canola Meal

W-DDGS

Crude protein, %

40.1

37.2

NDF, %

31.9

27.9

Ether extract, %

3.6

5.6

Ash

8.2

6.2

RUP, % of protein

52.5

39.2

During the study, the question on everyone's mind was "Which protein source provided the best value?" The answer is complicated and depends on the criteria selected to determine the true value of protein ingredients.

Cost of the ingredient. If the cost of the ingredient alone is used to calculate the value, then the answer is readily apparent. W-DDGS costs $100 less than canola meal, and on that basis would appear to be a bargain.

Cost of the protein. As Table 2 shows, the canola meal provides more protein than W-DDGS. The cost per ton of protein from canola meal is $360/0.401 = $897.76. The cost for W-DDGS is $260/0.372 = $698.92. Again, W-DDGS wins.

Cost of RUP. Newer methods of ingredient analysis show canola meal provides a substantial amount of rumen undegraded protein (RUP). Based on the method of determination used in the Agriculture & Agri-Food Canada study, the RUP value of canola meal was 52.5% of the protein and 39.2% for W-DDGS. Therefore, the cost of a metric ton of RUP from canola meal would be the cost of a metric ton of protein as determined in the above calculation, divided by the fraction of RUP: $897.76/0.525 = $1,710.02. The cost of RUP from W-DDGS is 698.92/0.392 = $1782.99. The RUP level found in canola meal provides a slight advantage.

Cost of the diet. The researchers were careful to ensure the concentrations of all nutrients except protein were similar for all diets. To balance the diets, modifications were needed to some of the base ingredients. As Table 3 shows, the costs of the diets were higher when canola meal was used.

3. Level of inclusion of protein meals in the diets and the calculated cost of the diets

 

-15% Crude Protein diet-

-17% Crude Protein diet-

 

Canola Meal

W-DDGS

Canola Meal

W-DDGS

Canola meal in the diet, % of DM

11.1

0

15.9

0

W-DDGS in the diet, % of DM

0

12.0

0

15.7

Cost/mt of diet DM, $

146.91

137.67

161.12

152.96

Cost of the results. What all of the above calculations fail to consider is the return on investment for the two protein sources. Although the canola meal diets were more costly than the W-DDGS diets, using current milk values, the canola meal diet produced better returns on investment.

4. Calculated value of two meals based on current Central U.S. milk prices

 

-15% Crude Protein diet-

-17% Crude Protein diet-

 

Canola Meal

W-DDGS

Canola Meal

W-DDGS

Value of milk, $/day

24.71

24.18

26.04

25.74

Cost of feed, $/day

5.07

4.79

5.49

5.31

Income over feed, $/cow/day

19.64

19.37

20.55

20.43

Head-to-head studies conducted at the U.S. Dairy Forage Research Center in Madison, Wis., demonstrated canola meal supported higher milk production than soybean meal. Studies conducted at the University of California-Davis similarly exhibited the advantages of canola meal over corn DDGS. In all cases, researchers attributed the responses to a superior amino acid profile with canola meal, along with its high RUP value. Formulating for amino acids may better allow nutritionists to predict the responses to protein sources used in diets for dairy cows. The ability to predict such responses can mean better returns on investment.

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