Pea - Cereal Mixtures for Forage Yield and Quality

Research Coordinator: Dr. Akim Omokanye

Location: Fairview Research Farm (NW-5-83-02-W6)

From: Peace Country Beef & Forage Association 2013 Annual Report


Peas are usually included in mixes to improve the quality of the feed. Peas and oats, barley or triticale are some of the most common types of intercropping. Pea/cereal mixtures can produce better quality silage than cereals alone. Pea silage could be 13-18% protein so theoretically a pea/cereal mix should have higher pro-tein than a cereal silage alone which is usually about 10% protein. In reality however, the potential protein benefits of peas in silage mixtures often are not attained because of the competitive effects of the cereal crop. Several studies have shown that pea/cereal mixtures can produce better quality silage than cereals alone, but the success of these intercrops is highly dependent on the seeding rates for both crops and making sure that there are enough peas in the mixture to influence feed quality. Legumes don’t need nitrogen (N) fertilizer and have higher forage protein content than cereals. Seeding mixtures of peas and cereals may reduce land, inputs and labour costs per unit of forage production, which will improve beef production efficiency and contribution margin.


Objectives

  • To compare the mixtures of forage peas with barley, oat and triticale for forage yield and quality

  • To communicate findings to beef cattle producers in the Peace Region and to other parts of Alberta through the RSVTs (The results will also be reported in the Alberta Seed Guide (www.seed.ab.ca)).

Methods

This trial is part of the Regional Silage Variety Trials. The trial was conducted at Fairview Research Farm (NW5-82-3W6) on RR #35, MD of Fairview. Soil test for the site at 0-6” indicated a pH of 5.4 and 8.8% organic matter. The site was left to fallow in the summer of 2012, but had a Pioneer® brand canola variety trial in 2011.


Seeding and Crop Management

Prior to seeding, the site was harrowed and then sprayed with Credit® for a pre-seed weed control. Three cereal varieties (Vivar barley, Pronghorn triticale & Murphy oat) and 2 forage type pea varieties (40-10 & CDC Horizon) were used for the trial. The treatments (9) consisted of 3 pure cereal crop plots (Vivar barley, Pronghorn triticale & Murphy oat) and mixtures of each cereal variety with each of 40-10 & CDC Horizon (6 mixtures in total).


The treatments were arranged in a randomized complete block design with four replications. Plot size at seeding was 8.5 m long 6 rows at 23 cm (9”) spacing between rows. Seeding rate was 250 live seeds/square meter for the pure cereals, corresponding to 100, 87 and 108 lbs/acre seeded respectively for Vivar barley, Murphy oat and Pronghorn triticale. For the mixtures, seeding was done at 50% (of pure cereal seeding rate) + 75% (of peas seeding rate). Seed rates of 104 and 115 lbs/acre were respectively used for 40-10 and CDC Horizon in the mixtures. A Fabro plot drill equipped with Atom jet openers was used to seed on May 23, 2013. All plots were fertilized with a blend of 48N-30P-10K-15S (lbs/acre). In crop spraying of the pure cereal plots was with Frontline XL. No spraying was done on the mixed plots. Hand weeding was done once to remove visible volunteer canola plants.


Field Notes and Forage Yield Estimation

Plant stand was visually inspected in all plots to assess adequacy of crop emergence at 4 weeks after seeding. Prior to harvest, notes were taken on plant lodging. Harvesting for forage yield was done at the soft dough stage for pure barley, milk stage for oat and late milk for triticale. Each mixture was harvested 10 days later after the cereal in the mixture was at the recommended stage of maturity for harvest. For each plot, four 3 m long inner rows were hand harvested and weighed for wet yield determination. About 0.5 kg of the freshly harvested materials was sub-sampled and air-dried for a few days to constant weight for forage dry matter (DM) yield estimation.


Forage Quality Analysis

The forage quality (% DM) was determined using two dry composite forage samples per treatment, one for replications 1 & 2, and the other for replications 3 & 4. The samples were analyzed in a commercial laborato-ry using standard laboratory procedures for wet chemistry analysis.


Results and Discussion

Forage Moisture and DM yield (Table 1)

Forage moisture at harvest was similar for pure cereals as well as pea-cereal mixtures. Moisture varied from 63.4 - 66.7% and was 64.7% on average.


DM yield varied from 6380 lbs/acre for CDC Horizon/Murphy mixture to 8473 lbs/acre for pure Vivar barley. Generally, pure cereals appeared to have slightly yielded more DM than peas-cereal mixtures. Pure Vivar barley appeared to have out yielded peas-Vivar barley mixtures by 740 - 934 lbs DM/acre. Pure triticale out yielded peas-triticale mixtures by 529 - 1221 lbs DM/acre. Pure oat out yielded peas-oats mixtures by 778 - 1410 lbs DM/acre.

Forage Quality (Table 1)

Protein varied significantly different among crop treatments. Pure triticale and 40 - 10/Pronghorn mixture had up to 13% protein. The other pure cereals and mixtures (except for 40-10/Vivar mixture) had >11.0%protein. With the exception of 40-10/Vivar barley mixture, all pure cereals as well as peas-cereal mixtures had adequate levels of protein required by a dry gestating and lactating cow. 40-10/Vivar barley mixture was sufficient for a dry gestating cow but not for a nursing cow.


Of the 5 macro minerals tested for, only K did not vary much among crop treatments. Forage Ca, P, Mg and Na contents all varied greatly among pure cereals and peas-cereal mixtures. Forage Ca content was greatly higher for pure Murphy oat and CDC Horizon/Murphy oat mixture. Five of the 9 mixtures had 0.20% P and above. Other mixtures had <0.20% P. Pure Murphy oat had the highest forage Mg content (0.42%). Pure Pronghorn triticale and 40-10/Murphy oat mixture had 2-8 times higher Na content than crop treatments.


For a lactating cow, only pure Vivar barley and mixtures of 40-10/Murphy oat and 40-10/Vivar oat were deficient in the amount of Ca needed by this category of cow. Only 40-10/Murphy oat and 40-10/Pronghorn triticale mixtures had up to the 0.26% P that has been suggested for a lactating cow. All pure cereals as well as peas-cereal mixtures had sufficient amounts of Mg, K and Na needed by a lactating cow.


Energy (TDN) values did not vary much among pure cereals as well as among peas-cereal mixtures. TDN val-ues varied from 60-64% for all crop treatments. Using TDN per cent, 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 ra-tion must have a TDN energy reading of 55 per cent in mid pregnancy, 60 per cent in late pregnancy and 65 per cent after calving. From the TDN values obtained in the pure cereals and peas-cereal mixtures in the present study, it is evident that all treatments had sufficient energy for a dry gestating cow, both in the mid and late pregnancy stages, but slightly fell short of the 65% TDN suggested for a lactating cow.

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