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Robert N. Oglesby DVM
Moderator
Username: Dro
Post Number: 16568
Registered: 1-1997
| | Posted on Sunday, Sep 10, 2006 - 2:11 pm: |   |
Concerning endophyte infected fescue, other than the problems associated with reproduction (prolonged gestation, weak neonates, and agalactia) other harmful effects on horses are not well documented. This is is contrast to cattle which do have foot problems, weight gain decreases, and increased sensitivity to environmental stress like heat. This is one of the first studies I have seen on how endophtyes effect horses. Essentially other ill effects were not found which is consistent with how well non-breeding horses are observed to do on endophyte infected fescue.
N Z Vet J. 2006 Aug;54(4):178-84.
Effects of initial and extended exposure to an endophyte-infected tall fescue seed diet on faecal and urinary excretion of ergovaline and lysergic acid in mature geldings.
Schultz CL, Lodge-Ivey SL, Bush LP, Craig AM, Strickland JR.
USDA, ARS Southern Plains Agricultural Center, 2881 F&B Road, College Station, TX 77845, USA.
AIM: To determine the amount of ergovaline and lysergic acid retained or excreted by geldings fed endophyte-infected seed containing known concentrations of these alkaloids, and the effects of exposure time on clinical expression of toxicosis. METHODS: Mature geldings (n=10) received diets containing either endophyte-free (E-) or endophyte-infected (E+) tall fescue seed during three experimental phases. The first phase (Days -14 to -1) was an adaptation phase, to allow all horses to adapt to a diet containing E- tall fescue seed. The second (Days 0 to 3) was the initial exposure phase to E+ tall fescue seed, used for the delivery of ergovaline and lysergic acid at 0.5 and 0.3 mg/kg of diet, respectively, to test the initial effects of exposure on routes and amounts of elimination of alkaloid. During this phase, half the geldings were exposed to an E+ diet while the rest served as controls by remaining on the E- diet. Once assigned to treatments, geldings remained on the same diet through the third phase (Days 4 to 21), which served as the extended exposure phase. Total outputs of faeces and urine were collected within each phase, to determine retention of ergovaline and lysergic acid and nutrient digestibility. Serum was collected weekly and analysed for activities of enzymes and concentrations of prolactin. Bodyweights (BW) and rectal temperatures were recorded weekly. RESULTS: BW, rectal temperature, enzyme activities and concentrations of prolactin in serum, and nutrient digestibility were not affected by treatment. Total intake of ergovaline by geldings on the E+ diet was 3.5 and 3.6 (SE 0.20) mg/day, and 2.1 and 2.3 (SE 0.11) mg/day were not accounted for in initial and extended phases, respectively. Lysergic acid was excreted in the urine (4.0 and 4.9 (SE 0.97) mg/day) and faeces (2.5 and 2.7 (SE 0.35) mg/day) at greater amounts than that consumed (2.0 and 1.9 (SE 0.09) mg/day) during the initial and extended exposure phases, respectively. Animals exposed to E+ seed for a period of 20 days appeared to excrete more (1.5 vs 1.2 mg/day; SE 0.08; p=0.03) ergovaline in the faeces than those exposed for only 4 days. CONCLUSIONS: Exposure time to the ergot alkaloids had a limited effect on the route of elimination or the amounts of ergovaline or lysergic acid excreted by horses. The primary alkaloid excreted was lysergic acid, and urine was the major route of elimination. These data will aid future research to improve animals' tolerance to toxic endophyte-infected tall fescue. |
