Trial Site: Fairview Research Farm
Research Coordinator: Dr. Akim Omokanye
From: Peace Country Beef & Forage Association 2017 Annual Report
There is growing interest in the potential for a multispecies cover crop mixture (cocktail) for forage-based livestock production. The idea of cocktails is still new in the Peace. Cover crops can be grown as a monoculture or in mixtures with other cover crops. A cocktail mixture is a number of cover crop species mixed together to take advantage of each of its species' unique offering to the producer's soil. Mixtures of cover crop species can be planted to optimize the benefits associated with cover crop use. The three major categories of commonly grown cover crops are grasses, legumes, and brassicas. Legumes in the mixtures can contribute N through symbiotic dinitrogen (N2) fixation, which can benefit non-legumes growing in the mixtures through transfer of N by the roots. Better forage quality, building soil organic matter and improving overall soil health are some of the reasons given by producers who have seeded cover crops.
Objective
To evaluate cocktail cover crops using multi-species cover crop mixtures versus cool season forage-type cereals for forage production.
Methods
Project Site: Fairview Research Farm (NW5-82-3W6) on RR #35, MD of Fairview.
Previous crop: Chemical fallow in 2016, barley in 2015. Site soil information (0-6” depth): Soil tests done at Exova laboratory (Edmonton) prior to seeding showed pH = 5.8 and soil organic matter = 7.0%.
The field was cultivated (disked and harrowed) before seeding.
Experimental Design: Randomized complete block design in 3 replications in small plots (118.8 ft2 )
Treatments (18 treatments in total as shown below in Table 1): 14 mixtures, 4 monocrops as checks (CDC Haymaker oats, CDC Maverick barley, Bunker triticale & AC Andrew soft white wheat).
The cocktails were pre-mixed before seeding.
Except for cocktail #7, the legumes were inoculated at seeding.
Seeding Date: Seeding was done on May 31.
Seeding method: 6-row Fabro plot drill with 9” row spacing.
Fertility: No fertilizer applied to cocktails as well as the monocrop cereals (checks).
Spraying: No pre-seed, pre-emergent or in-crop spraying was done.
Forage yield was determined on August 14, corresponding to 75 days after seeding. Prior to harvest, efforts were made to identify the crop varieties in each cocktail mixture and we compared these crop varieties to the supposed list of seeded crop varieties in the mixtures. This was done to ensure that the final result of a particular cocktail mixture reflects the intended crop composition. A day before forage harvest, the plots were scanned with a GreenSeeker Technology instrument to obtain NDVI values. Forage quality was also determined.
Results & Implications
Forage Dry Matter (DM) Yield (Table 2)
The forage DM yield was highest for AC Andrew soft white wheat (8925 lbs DM/acre), closely followed by Bunker triticale (8832 lbs DM/acre) and then cocktail #5 (8644 lbs DM/acre). Only one (cocktail #5) of the 14 cocktails had >8000 lbs DM/acre. Other cocktails had <8000 lbs DM/acre. Three of the monocrop cereals (wheat, barley and triticale) had >8000 lbs DM/acre, and the fourth monocrop cereal (oats) had <8000 lbs DM/acre. Cocktails #4, 9, 12 and 13 had far less forage DM yield than other cocktails as well as monocrop cereals.
Cocktails #6 & #7 contained only barley and hairy vetch. The hairy vetch in Cocktail #6 was inoculated, while that of cocktail #7 was not. The differences between the two, which was in favour of cocktail #6 (inoculated) was high, resulting in a yield advantage of 791 lbs DM/acre over cocktail #7. This confirms the need to inoculate legumes before seeding. Visual observation just before forage harvest showed that the barley in cocktail #6 seemed to grow slightly taller than barley in cocktail #7 (see Picture below).
Forage Quality (Table 2)
Meeting the basic nutrient requirements of beef cows is a key component of meeting cow herd production and profitability goals for the beef cattle enterprise. Adequate nutrition is vital for adequate cow reproduction, cow and calf health, and growth of all classes of cattle. Nutrient requirements of cattle change throughout the year based upon stage of the production cycle, age, sex, breed, level of activity, pest load, and weather conditions.
Crude Protein (CP): The forage CP was highest for cocktail #12 (23.9% CP), followed closely by cocktail #13 (22.7% CP) and then cocktail #10 (19.8% CP). Other cocktails had 11.1– 16.0% CP. The improvement in forage CP content from cocktails #10, 12 and 13 over other cocktails was probably due to the presence and higher rates of annual/Italian ryegrass (particularly Italian and Green spirt) and brassicas (up to 20% in the premixed seeded cocktails).
Brassicas and annual ryegrasses are usually high in forage CP and are highly digestible as well. However, caution may need to be taken when feeding brassicas. Introduce stock slowly to the brassica crop and never with an empty rumen to minimize problems. All cocktails seemed to fare better in terms of forage CP than the 4 monocrop cereals tested (barley, wheat, oats and triticale).
Protein is a building block. The beef cow’s protein requirements change throughout the year. The requirement for protein is dependent upon the age of the cow, stage of production, and level of production. Protein requirements are additive during any point in the cow’s production cycle. The general beef cow rule of thumb with protein is 7-9-11, which means an average mature beef cow requires a ration with crude protein of 7 per cent in mid pregnancy, 9 per cent in late pregnancy and 11 per cent after calving.
Lactation is the most stressful time in the cow’s production cycle. Milk contains a large concentration of protein. The source of the protein in milk comes either from dietary sources or mobilization of body lean tissue. Mobilization of lean tissue decreases the overall body condition score of the cow. Research indicates that maintenance of body condition score from calving to rebreeding is imperative to ensure acceptable conception rates. Therefore adequate protein from the diet is an important nutritional consideration.
All cocktails tested in this study were able to meet and in most cases, exceed the CP requirements of mature beef cattle. For the monocrop cereals, both soft white wheat and barley conveniently met the CP requirements of mature beef cattle than oats and barley. Both oats and barley slightly fell short of meeting the 11% CP needed by lactating beef cows.
Energy (Table 2)
Energy gives the ability to use the building blocks for growth and other productive purposes. Energy requirements are expressed in the tables in terms of total digestible nutrients (TDN) and net energy for maintenance (NEM). Three of the cocktails (#5, 12 and 13) had >70% total digestible nutrients (TDN). Other cocktails had 61.6 - 68.7% TDN. Barley had higher TDN (69.4% TDN) than other monocrop cereals. The 3 other cereals had similar TDN. Most cocktails had higher TDN than monocrop soft white wheat, oats and triticale.
Cow energy requirements change throughout the year. The requirement for energy by the mature cow is a dynamic situation because the production cycle is not static. At no point in a yearly production cycle does a cow experience only maintenance energy requirements. The energy requirement for lactation is a function of milk yield, milk fat %, and milk protein %.
For TDN, the rule of thumb is 55-60-65. This rule says that for a mature beef cow to maintain her body condition score (BCS) through the winter, the ration must have a TDN energy reading of 55% in mid pregnancy, 60% in late pregnancy and 65% after calving. Nine of the cocktails conveniently met and in most cases exceeded the TDN requirements of mature beef cattle, while the remaining 5 cocktails fell slightly short of meeting the 65% TDN needed by lactating beef cows.
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In terms of net energy requirements for maintenance (NEM), all cocktails and the 4 monocrop cereals exceeded the 1.08-2.29 Mcal/kg NEM for growing and finishing calves, 0.97-1.10 Mcal/kg NEM for dry gestating cows and 1.19-1.28 Mcal/kg NEM for lactating beef cows. Also, all cocktails and the 4 monocrop cereals were within 0.53-1.37 Mcal/kg net energy for gain (NEG)requirements by growing and finishing beef calves.
Young beef cattle (growing and finishing calves) require 65-70% TDN. Nine of the cocktails tested here and CDC Austenson barley monocrop were either within or exceeded this range for young beef cattle.
Minerals (Table 2)
Most cocktails had higher forage Ca than monocrop cereals. All cocktails and the 4 monocrop cereals had enough forage Ca for a dry gestating beef cow, but only 6 cocktails had the required Ca (0.58% Ca) for a lactating beef cow. The other cocktails and the 4 monocrop cereals all fell short of meeting the Ca requirements of a lactating beef cow.
Only 2 of the cocktails (#7 & 11) and CDC Austenson barley did not have the required 0.16% P needed by dry gestating beef cows. For the P requirements of lactating beef cows (0.26% P), only cocktails #10 and #12 had adequate forage P.
The requirements of K, S (except cocktail #9), Fe (except cocktails #6 and #7) and Zn were met by all cocktails and monocrop cereals tested.
Dry gestating beef cows require 0.06-0.08% Na and 0.10% Na during lactation. Except for cocktails #5 and #8 and soft white wheat, the Na requirements of mature beef cattle were met by cocktails and monocrop cereals tested.
None of the cocktails or monocrop cereals were able to meet the complete macro and trace minerals measured here, so a supplemental mineral program may still be required for mature beef cattle when some of the cocktails and any of the monocrop cereals are being used.
Conclusion
The forage DM yield was highest for AC Andrew soft white wheat (8925 lbs DM/acre), closely followed by Bunker triticale (8832 lbs DM/acre) and then cocktail #5 (8644 lbs DM/acre). Only one (cocktail #5) of the 14 cocktails had >8000 lbs DM/acre, while other cocktails had <8000 lbs DM/acre. Cocktails #4, 9, 12 and 13 had far less forage DM yield than the other cocktails as well as monocrop cereals. Visual observation just before forage harvest showed that the barley in cocktail #6 (with inoculated hairy vetch) seemed to grow slightly taller than barley in cocktail #7 (with non-inoculated hairy vetch) and had a yield advantage of 791 lbs DM/acre over cocktail #7, further confirming the need to inoculate legumes before seeding. All cocktails tested in this study were able to meet and in most cases, exceed the CP requirements of mature beef cattle. None of the cocktails or monocrop cereals were able to meet the complete macro and trace mineral requirements of mature beef cattle, so a supplemental mineral program may still be required when feeding beef cattle.
Some Notes on Tillage Radish
The tillage radish has been bred/developed to produce a large taproot and penetrate compacted soil layers in an effort to increase soil aeration and water infiltration, decrease compaction and provide increased rooting depth opportunities to successive crops. Although tillage radish may not penetrate and grow as deeply in some of our “gumbo” type soils as we might hope, they can serve another useful purpose that can be of great value to producers - nutrient retention. The large taproot that is developed by tillage radish can absorb and retain a significant amount of macro- and micronutrients that might otherwise be prone to leaching or other loss mechanisms. Think of the tillage radish taproot as a giant sponge that will absorb residual nutrients from the soil and hold them until termination in the fall. The other nice thing is that the nutrients which are absorbed by the taproot are readily available to the following crop as the taproot is mostly water and desiccates and decays, quickly releasing those nutrients for uptake and utilization by the following crop. However, care needs to be taken on the amount of tillage radish used in cocktails because of its competitive nature, which results from its deep tap root sucking up nutrients from the soil at the expense of nearby or surrounding crops. Sources: http://www.deltafarmpress.com/management/tillage-radish-cover-crop-tips-maximize-its-benefits https://www.albertafarmexpress.ca/2015/09/25/tapping-into-nutrients-and-tackling-compaction-withtillage-radishes/