Trial Site: Fairview Research Farm
Research Coordinator: Dr. Akim Omokanye
From: Peace Country Beef & Forage Association 2017 Annual Report
Many annual crops are suitable for inclusion in cocktail mixtures for forage production (grazing, silage or greenfeed) and to improve soil health. Some of the broadleaf cover crops are still relatively new to us in the Peace, and questions have been asked about the forage quality of some of these broadleaf crops in order to determine their suitability for livestock production. This year, we seeded sunflower, phacelia and sugar beet for demonstration purposes and to determine what the forage quality of these crops would be in this area. The crops were seeded at the recommended seeding rates in small plots replicated twice.
Results
Forage Crude Protein (CP)
The 3 broadleaf crops had impressive forage CP, with sunflower having the highest value (19.8% CP). Both phacelia and sugar beet had similar forage CP (about 18% CP). With these forage CP values, the 3 crops had far more protein than is required by both young and mature beef cattle.
Forage Detergent Fibres
The forage ADF and NDF were both lower for sugar beet forage than sunflower and phacelia. For both ADF and NDF, lower values are preferred for livestock production. The ADF values are important because they relate to the ability of an animal to digest the forage. As ADF increases, digestibility of forage usually decreases. The NDF values are important in ration formulation because they reflect the amount of forage the animal can consume. As NDF percentage increases, forage DM intake will generally decrease. Comparing the 3 broadleaf crops, the lower ADF and NDF values for sugar beet would suggest that when all the broadleaves are presented side by side to cows in a preference study, sunflower and phacelia would likely be less preferred and consumed less than sugar beet.
Generally, NFC is more rapidly digested than fibre. It is a significant source of energy for the rumen microbes. The microbes also use NFC to make microbial protein. From the 3 broadleaves tested, sugar beet also had higher NFC than sunflower and phacelia.
Minerals
Phacelia had the highest forage Ca. Sunflower had the highest forage P and Cu. Sugar beet had higher forage K, Mg, S, Fe, Zn and Mn.
It is very important to note that the Ca requirements of both young and mature beef cattle were far exceeded by the 3 broadleaves tested, indicating that including any of these crops in a cocktail mixture would probably help improve forage Ca of the cocktail. Only sugar beet fell short of meeting the P requirements of young and mature beef cattle. Both sunflower and phacelia had more than what calves and mature beef cattle need for P.
The requirements of K, Mg, S, Fe, Zn and Mn have all been met by the 3 broadleaves.
Sunflower and phacelia did not have enough Na for mature beef cattle, while sugar beet far exceeded the Na needed by mature beef cattle.
The Cu requirement of young and mature beef cattle is 10 ppm. Looking at the 3 broadleaves, only sunflower was able to meet the required amount of Cu. Both phacelia and sugar beet did not have enough Cu for beef cattle.
Energy
Energy is probably the most important nutritional consideration in beef cattle production. The forage energy (%TDN) was generally >60% TDN for all broadleaves tested. Sugar beet had the highest forage TDN (80% TDN), followed by sunflower (77% TDN) and then phacelia (61% TDN). All broadleaves tested here were therefore able to meet the TDN requirements of a gestating cow. For a lactating cow, which requires 65% TDN, all broadleaves (except for phacelia), met the requirement.
Other forms of energy measured (NEL , NEM & NEG) all appeared to be higher for sugar beet than sunflower and phacelia. A range of 0.97-1.10 Mcal kg-1 NEM (net energy for maintenance) has been recommended for a dry gestating beef cow and a range of 1.19-1.28 Mcal kg-1 for a lactating beef cow. The NEM is an estimate of the energy value of a feed used to keep an animal in energy equilibrium, i.e., neither gaining nor losing weight. Generally, the 3 broadleaves tested here exceeded the NEM requirements of mature beef cattle during pregnancy and even after calving.
Conclusion
From the forage CP, energy and minerals measured here for the 3 broad leaves, one can say that the nutrient requirements of both young and mature beef cattle have been met by these 3 broadleaves (except for sugar beet for P, and both phacelia and sugar beet for Cu). It therefore shows that including any of the 3 broadleaves tested in cocktail mixtures should help improve the forage quality of the cocktails for beef cattle. It is however important to note that both sunflower and phacelia seem to have better growth in the area than sugar beet.