ADSA update

94

Source: Canola Council of Canada

The annual American Dairy Science Association Meetings were held in Kansas City, Missouri from July 21 through 24. This annual meeting provides new information on research in progress or recently completed that relate to all aspects of dairy from rearing of calves through to the finished products.

Two key abstracts on the feeding value of canola meal for lactating dairy cows were presented at this meeting.

Abstract 1186 was presented by Jordan Kuehnl, Ph.D candidate at the University of Wisconsin, supervised by Dr. Kenneth Kalscheur, US Dairy Forage Research Center. The objective of the study was to evaluate canola meal as compared to soybean meal in diets for cows in mid-lactation with high or low residual feed intakes. Residual feed intake (RFI) is a measure of feed efficiency, defined by determining the difference between the actual and expected feed intake. Cows with low values are genetically more efficient than those with high RFI values.

Cows were grouped according to their determined RFI. Within each RFI category (high or low) cows were given a diet where the major protein source was either soybean meal or canola meal formulated to provide 16.5% crude protein.  There were no diet *RFI interactions for any of the measurements taken. This means that the cows in both RFI categories responded the same to the two protein sources.

Cows that received the diet based on canola meal gained 9.5 kg more body weight and outperformed the cows given the soybean meal diet, as is shown in the table below:

Soybean meal vs canola meal for mid lactation cows (averages for both relative feed intake treatments)

Protein Source Soybean Meal Canola Meal
Dry matter intake (DMI), kg 25.4 27.0
Milk yield, kg 41.4 44.3
Energy corrected milk (ECM), kg 45.6 47.8
Total solids yield, kg 5.49 5.79
ECM/DMI 1.81 1.78
Milk urea nitrogen, mg/dL 12.7 12.2

In the second canola meal presentation, Abstract 1181 (Cueva et al.) researchers from Pennsylvania State University compared the performances of cows given extruded soybean meal as compared to solvent extracted canola meal. The logic behind the study was to demonstrate that extruded soybean meal would provide an amount of escape protein that was more in line with the amount provided by canola meal.

The diets were formulated to provide 16.5% crude protein, and rumen protected methionine and lysine were added to both to ensure that neither amino acid was limiting.  The researchers found no differences in dry matter intake or energy corrected milk yield. However, milk fat yield was greater with the extruded soybean meal diet, while milk protein yield was greater with the solvent extracted canola meal diet. There were no differences in blood amino acid levels, but blood urea N levels were lower with the canola meal diet. The researchers concluded that extruded soybean meal, along with rumen protected amino acids can be used to replace canola meal in diets for mid-lactation cows.

In addition, canola forage, a relatively new ingredients continues to gain in importance. Canola forage has higher concentrations of sugars than many other forages, and this forage has been shown to reduce the production of enteric methane. In a University of New Hampshire study (Abstract 1305), led by graduate student L.H.P. Silva, Jersey cows were given diets with either 60% alfalfa baleage, or 20% alfalfa baleage and 40% canola forage. The researchers hypothesized that if less energy was lost as enteric methane, that energy would end up as either milk or tissue (weight gain). The results below show that the extra energy was captured as weight gain in this study.

  Alfalfa Forage vs Canola Forage on methane production and energy utilization

Forage Source Alfalfa Alfalfa/Canola
Dry matter intake (DMI), kg 22.0 21.1
Energy corrected milk (ECM) yield, kg 27.0 26.6
Methane production, g/day 452 300
Methane production, g/kg of ECM 16.5 11.2
Milk Energy,Mcal net energy 18.3 18.7
Tissue energy, Mcal net energy 11.9 16.6