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  Discussion on Reed Canarygrass toxicity
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Member:
mcashman

Posted on Friday, Jan 1, 2016 - 8:41 am:

I have a friend who has been having trouble getting her horse to eat hay. She recently got some hay from NY state that her horses liked. We investigated and the dealer says it is reed canarygrass. But further research shows reed canarygrass as accumulating alkaloids and selenium and being toxic to horses. She has stopped feeding the hay. I checked, and some publications, even from universities, suggest it as a pasture plant, while others call out the toxicity. My inclination would be to not feed it, but I must admit that I am worried that hay producers do not think of it as toxic. Any thoughts, research articles or experience?

https://www.horsedvm.com/poisonous/reed-canary-grass/ is the relevant article

Thanks for any help you can provide.
Moderator:
DrO

Posted on Friday, Jan 1, 2016 - 12:02 pm:

Hello Mark,
Reed Canarygrass has been used as a forage for livestock for hundreds of years but can have a problem with alkaloids. However recent low alkaloid varieties have been developed. I cannot find anywhere that selenium toxicity has occurred but it is known to concentrate selenium, as does alfalfa, so I suspect that may be a problem when grown on high selenium soils. I know it has been used safely for horse forage and here are two good references.
DrO

Reed Canarygrass
Craig C. Sheaffer, P.R. Peterson, and N.J. Ehlke

Reed canarygrass is believed to be native to the temperate regions of Europe, Asia and North America (Ahlgren, 1956, Forage Crops). It has been cultivated and utilized as a forage in the United States since colonial times. Because of its tolerance of wet conditions and its ability to form a dense sod, it has been extensively used in soil conservation projects for stream bank, pod, and waterway stabilization. It is unchallenged in its value to heal and control gullies. Unfortunately, because of its extensive production of light seed and extensive underground stem system, reed canarygrass spread is sometimes difficult to control and it has been categorized as invasive.

Traits
Adaptable to a diversity of soils and climates
Reed canarygrass tolerates a soil pH range of 4.9 to 8.2. Reed canarygrass is particularly adapted to wet soils. Mature plants have tolerated up to 7 weeks of spring flooding. Reed canarygrass has superior persistence on poorly drained soils, yet its yield and persistence under moisture deficits is equal to or superior to other commonly grown cool season grasses.

Thrives under diverse cutting management
Reed canarygrass is among the most persistent perennial gasses adapted to Minnesota. It has exceptional winterhardiness and maintains yield under cutting strategies designed to produce both biomass through infrequent cutting and high quality forage through frequent cutting.

Suitable for legume mixtures
Grasses like reed canarygrass are mixed with legumes to minimize bloat potential, soil erosion, legume heaving, and weed invasion inherent in legume monocultures and to increase hay-drying rates. Recommended grass composition varies from 20 to 50% depending on use of the forage. We have found that reed canarygrass mixtures with alfalfa and kura clover had the greatest stability over time. Unfortunately, smooth bromegrass and timothy often fail to persist when planted in mixture with alfalfa and kura clover and orchardgrass is too competitive. The forage quality of reed canarygrass is equivalent to that of other perennial cool-season grasses. Like those grasses it's quality is greatly influcenced by stage of maturity at harvest. Quality declines as maturity increases.

Wastewater application and bioremediation
Reed canarygrass has superior capacity to persist and remove nitrogen when irrigated with municipal and industrial waste effluent. Table 2 shows the results from a wastewater application study in southern Minnesota. Because of its exceptional ability to take up N reed canarygrass has been used for liquid manure disposal. Table 3 shows the results from a liquid manure application study in southern Minnesota. Note that reed canarygrass stands were actually improved by nitrogen fertilization.

Low alkaloid reed canarygrass
Lack of palatability to livestock is frequently cited as why this agronomically superior species is not more widely grown. Older varieties such as Rise and Vantage, and most native types growing in wetlands, contain significant amounts of indole alkaloids.Alkaloids are bitter, complex, nitrogen containing compounds that can reduce the performance of grazing animals. Animal performance may be highly negatively correlated with total alkaloid concentration; however, the two types of alkaloids in reed canarygrass have been documented to affect grazing animals somewhat differently. High concentrations of simple gramine alkaloids reduce palatability. The more complex tryptamine-carboline alkaloids cause diarrhea as well as reduce palatability. The threshold indole alkaloid level beyond which sheep will consistently reject reed canarygrass in cafeteria offerings is about 0.4 to 0.6% dry weight. Indole alkaloid concentrations at or above 0.2% dry weight have been shown to reduce gain in grazing lambs. It should be noted that sheep are more sensitive to alkaloids than cattle and will likely tolerate high concentrations in the forage.

Varieties of reed canarygrass
Most native types of reed canarygrass growing in wetlands as well as the traditional varieties such as 'Rise' have high concentrations of alkaloids. 'Venture' and 'Palaton' were the first commercial varieties to be developed (1985) with enhanced palatabliity due to low gramine, and no tryptamine and carboline alkaloids concentrations. Another low alkaloid variety, 'Rival' also was released in Canada about the same time. In the summer of 2002, we evaluated the alkaloid concentration of several reed canarygrass varieties. We were especially interested in alkaloid levels in Marathon and Chiefton, the two newest low alkaloid varieties. The total alkaloid concentration of the leaf blades ranged from0.19 to 0.26 (Table 2) and consisted only of gramine alkaloids. Vantage, the oldest entry in the trial, contained the highest alkaloid concentrations. While these levels in leaf blades exceeded the threshold level for affecting lamb performance, it should be noted that we sampled only leaf blades that usually contain the highest alkaloid concentrations. Grazing animals will likely consume portions of the stem, thereby, diluting the alkaloid levels by ¼ to ½ depending on the amount of stem materials consumed.
J Anim Sci. 2006 Nov;84(11):3104-9.


Voluntary intake and digestibility of reed canarygrass and timothy hay fed to horses.

Ordakowski-Burk AL1, Quinn RW, Shellem TA, Vough LR.
Author information
Abstract
Thousands of hectares of timothy (Phleum pretense L.) grown in the Mid-Atlantic region are infected by cereal rust mite (Abacarus hysterix) that causes discoloration and curling of leaves, decreased nutritional quality, and substantial decreases in yield. A decline in production of timothy hay can lower income for hay producers and cause horse owners to search for alternative hays. Low alkaloid reed canarygrass (Phalaris arundinacea L.) hay has potential as an alternative to timothy hay because it grows well in the Mid-Atlantic region, is believed to have a similar nutrient quality to timothy, and is not as susceptible to cereal rust mite. Eleven mature, stalled Thoroughbred geldings (549 +/- 12.1 kg) that were exercised daily were used to compare voluntary DMI and apparent nutrient DM digestibility of timothy and low-alkaloid Chiefton variety reed canarygrass hay. Horses were paired by age and BW and randomly assigned to timothy or reed canarygrass hay during a 14-d period to measure voluntary DMI followed by a 4-d period to measure apparent DM digestibility. Both hays met the minimum requirements for DE, CP, Ca, P, K, Fe, and Mn, but they did not meet the minimum requirements for Cu, Zn, and Na for horses at maintenance and averaging 550 kg of BW. Timothy hay seemed to have a lower CP concentration (14.4%) compared with reed canarygrass hay (17.1%) and a more desirable Ca:P ratio at 1.6:1 compared with 0.8:1 for reed canarygrass hay. Horses fed timothy consumed more hay (P <0.001) during the voluntary DMI period compared with horses fed reed canarygrass. Greater voluntary DMI of timothy occurred on d 1, 3, and 5 (P <0.05), but DMI was similar for other days. Apparent DM digestibility was greater in horses fed timothy hay by 9.6% compared with horses fed reed canarygrass hay (P <0.05). Horses fed timothy had greater DM digestibility of ADF (P = 0.001), NDF (P = 0.001), sugar (P = 0.05), and Ca (P = 0.001) but lower apparent DM digestibility of CP (P = 0.012) and crude fat (P = 0.004). Timothy hay was superior in voluntary DMI and apparent DM digestibility compared with low-alkaloid reed canarygrass hay fed to horses.
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