Improved Lamb Performance Associated with Breeding for Alkaloid Reduction in Reed Canarygrass1
- G. C. Marten,
- R. M. Jordan and
- A. W. Hovin2
We earlier documented that indole alkaloid concentration of vegetatively propagated reed canarygrass (Phalaris arundinacea L.) clones was inversely associated with average daily gains of lambs and steers. Our objectives were to determine whether alkaloid concentration and type in two commercially available cultivars (‘Rise’ and ‘Vantage’) and in a low-alkaloid, tryptamine-carboline-free strain (MN-76) were associated with performance and health of grazing lambs. These seed sources of reed canarygrass were each planted in three pastures (0.27-ha/pasture) in a randomized complete block design.
Lambs that grazed MN-76 gained from 51 to 95% more per day than did those that grazed Rise and from 14 to 87% more than did those that grazed Vantage during a 2-year period. Rise contained a mean of 0.28 to 0.32% dry wt of a mixture of gramine and tryptamines-carbolines, Vantage contained 0.20 to 0.33% gramine, and MN-76 contained 0.09 to 0.12% gramine. The three grasses did not differ in most other quality components, but MN-76 had up to 8% less cell walls and up to 9% more crude protein during the 2 years, as well as up to 28% more Ca during Year 1. The correlation between total indole alkaloid concentration of the grasses and lamb average daily gain was −0.97 in Year 1 and −0.66 in Year 2. Incidence of diarrhea among lambs was 4 to 26 times greater when they grazed Rise compared to Vantage or MN-76.
We conclude that the indole alkaloid concentration threshold in reed canarygrass at or above which lambs will show reduced gain is about 0.20% dry wt, that diarrhea in grazing lambs specifically caused by consumption of reed canarygrass is very likely due to tryptamine-carboline alkaloids, and that MN-76 is a biologically significant grass breeding advance.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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