Persistency of Sainfoin in Alfalfa Pasture Mixtures: A Research Update

Trial Site: Fairview Research Farm (NW5-82-3W6) on RR #35.

Research Coordinator: Dr. Akim Omokanye

From: Peace Country Beef & Forage Association 2017 Annual Report


Sainfoin is a perennial forage legume that does not cause bloat because of its condensed tannin concentration. Condensed tannins are very effective at preventing deadly pasture bloat in ruminants. Studies have shown that 15% or more sainfoin in alfalfa mixture can significantly lower, and in certain cases eliminate, the risk of pasture bloat. However, until recently, available sainfoin varieties have not survived well in mixed stands with alfalfa, or have not regrown at the same rate after the first cut or grazing and so cannot be used with alfalfa for reducing pasture bloat. Studies have shown that new experimental sainfoin lines are more competitive and have improved regrowth rates compared to older sainfoin varieties. Sainfoin is said to be as nutritious and palatable as alfalfa, and more tolerant of both cold and drought.


Methods

Three experimental sainfoin lines (LRC05-3900, LRC05-3901, LRC05-3902) along with an older sainfoin variety called Nova (check) were each seeded in mixtures with AC Grazeland alfalfa on May 23, 2013 at the Fairview Research Farm (NW5-82-3W6) on RR #35. Both sainfoin and alfalfa were seeded in the same row (same row mixtures). AC Grazeland alfalfa is a low-bloat potential alfalfa, because this variety results in a slower initial rate of digestion, which helps prevent the onset of bloat. The soil at the test site had a pH of 5.4 and 8.8% organic matter before seeding. Each mixture was seeded with 15 lbs/acre of sainfoin and 6 lbs/acre of AC Grazeland alfalfa, indicating that half of the usual recommended seeding rates were used for both legumes.


The 4 treatment mixtures were replicated 4 times in small plots, which had been arranged in a randomized complete block design. Seeding was 0.5-0.7” deep, and the seed was inoculated. We applied 40 lbs/acre of 11-52-0 at seeding in 2013. Assure II and Basagran Forte were used to control volunteer oats & canola and other broad leaf weeds in the seeding/establishment year (2013).


Cutting was done twice yearly in 2014 and 2016, while in 2015 and 2017, only one cut was made. The first cut was when sainfoin was at 40-50 % bloom (alfalfa was at 20-30% bloom) and mostly from June 20-23 every year. The second cut was 6 weeks after the first cut. Please note that the highest risk of bloat occurs when legumes are in the pre-bud or vegetative stage. In 2015 and 2017, only one cut was possible because deer had selectively grazed down all sainfoin stands in the mixtures just before the second cut was to be taken. In addition to deer selectively grazing down the sainfoin, Fairview was also dry in 2015. From 2014 to 2017, forage dry matter (DM) yield and percent composition (proportion) of sainfoin and alfalfa in the mixtures was determined.


Results Obtained and Implications

Total Forage Dry Matter Yield (Figure 1)

In general, total DM yield at any particular cut was statistically similar for the sainfoin - alfalfa mixtures in each year (2014, 2015, 2016 & 2017). In 2014 (one year after seeding), total DM yield was generally lower for the 2nd cut (1143-1495 lbs DM/acre) than 1st cut (3114-3685 lbs DM/acre). The lower total DM yield obtained for the 2nd cut in 2014 was due to low moisture.


Proportion of Sainfoin and Alfalfa in the Mixtures

The proportions of sainfoin in alfalfa mixtures at every cut are shown in Table 1. During the first 3 years after seeding (2014, 2015 and 2016), with the exception of Nova sainfoin in 2016 (which had 5-6% sainfoin in the mixtures), the proportion of sainfoin in alfalfa mixtures was generally >18%. But in 2017, all sainfoin lines have had great reduction in population, varying from 0-13% in the alfalfa mixture. The check (Nova sainfoin) had completely disappeared in the mixtures.

It is important to note that the 3 experimental sainfoins consistently formed 20% or more in the mixtures from 2014 to 2016. This is important because at least 15% sainfoin needs to be present in the alfalfa stand to avoid bloat. Though there was still some sainfoin stands in the mixtures in 2017 for LRC-3900, LRC-3901, LRC3902 (AC Mountainview), this was not enough to reduce or eliminate the incidence of alfalfa bloat, as they all fell short of the required 15% or more sainfoin in alfalfa mixtures (Table 1 and Figure 2).


Compared to the 3 experimental lines, the drastic drop in the proportion of sainfoin for Nova from a mean of 22% in 2014 to a mean of 6% in 2016 and to a complete disappearance by 2017, probably confirms that an older sainfoin variety such as Nova wouldn’t be as competitive as the new sainfoin in alfalfa pasture mixtures. Our study further shows that when seeded with alfalfa, the experimental sainfoins should be able to provide bloat protection for more growing seasons than Nova (which only lasted for 2 years after seeding) or other older sainfoin varieties.

Summary

Over a period of 4 years of cutting, our results show that Nova sainfoin may not be good competitor with alfalfa in pasture mixtures, compared to any of the 3 experimental lines. As indicated earlier, studies have shown that 15% or more of sainfoin in an alfalfa pasture mixture would significantly lower, and in certain cases eliminate, the risk of bloat. Our study here at the Fairview Research Farm indicates that Nova sainfoin, which was reduced to just 6% in the alfalfa pasture mixtures by 2016, may not have the potential to lower bloat a few years after seeding. The newer lines, however, still had a few more productive years. Our thought is that the selective grazing down of the new sainfoin lines a few times may have contributed to lower stands of sainfoin recorded in 2017. One (LRC05-3902) of the 3 experimental sainfoin lines used in this study has been released as AC Mountainview sainfoin. The use of AC Mountainview sainfoin variety in alfalfa pasture mixtures is recommended.

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