Physiological and digestive effects of Neotyphodium coenophialum-infected tall fescue fed to lambs1

Abstract

The digestive responses and degradation of ergovaline and production of lysergic acid in the rumen of sheep offered Neotyphodium coenophialum-infected tall fescue straw at 2 ergovaline levels were investigated. Six crossbred wethers (56 +/- 3.0 kg of BW) were used in a randomized crossover design involving 2 treatments, for a total of 6 observations per treatment. The experiment consisted of two 28-d feeding periods with a 14-d washout period between them. The treatments were 1) tall fescue straw containing <0.010 mg of ergovaline/kg (E-), and 2) tall fescue straw containing 0.610 mg of ergovaline/kg (E+). Feed, orts, and feces were measured and analyzed for DM, ADF, and CP, and used to determine digestibilities. Feed and water intake were monitored throughout the feeding periods. Body weight and serum prolactin levels were measured at the beginning and end of each feeding period. Ruminal fluid was sampled 3 times (d 0, 3, and 28) during each 28-d feeding period for determination of ergovaline, lysergic acid, ammonia, and pH. Samples were collected before feeding (0 h) and at 6 and 12 h after feeding. Total fecal and urine collection commenced on d 21 and continued until d 25 of each feeding period. Ruminal ammonia, ruminal pH, and rectal temperature were not influenced by ergovaline concentration (P > 0.10). Digestion of DM, ADF, and CP was not different between treatments (P > 0.10). Daily water intake was less for the E+ diet (2.95 vs. 2.77 L/d; P < 0.05) as was serum prolactin (22.9 vs. 6.4 ng/mL; P < 0.05). Ergovaline concentration in ruminal fluid increased over sampling days at each sampling time (P < 0.05). Lysergic acid concentration in ruminal fluid increased over time from d 0 to 3 (P < 0.05) but was not different between d 3 and 28 (P > 0.10). In the E+ treatment, ergovaline was not detectable in the urine, whereas the concentration in the feces was 0.480 mg/kg. Lysergic acid was detected in the diet of the E+ treatment at 0.041 g/kg, lysergic acid in the urine was 0.067 mg/kg and in the feces was 0.102 mg/kg. The apparent digestibility of the alkaloids was 64.2% for ergovaline and -12.5% for lysergic acid. Approximately 35% of dietary ergovaline and 248% of dietary lysergic acid were recovered in the feces and urine. The appearance of lysergic acid in the feces, urine, and ruminal fluid is likely due to microbial degradation of ergovaline in the rumen and further breakdown in the lower digestive tract.

Mycotoxins in cattle feeds and carry-over to dairy milk: A review

“…Recent data show that following ingestion of ergovaline-contaminated tall fescue straw, not only ergovaline, but also lysergic acid is detectable in the urine and faeces of exposed cattle. A mass-balance study revealed that the toxin concentration in ruminal fluid apparently increases over time (De Lorme et al 2007). These unexpected findings resulted in the hypothesis that the rumen fermentation processes can liberate non-extractable toxins (escaping the initial feed analysis) and metabolize ergovaline into lysergic acid that might be even be absorbed through the ruminal wall (Hill et al 2001).…”

Ergovaline, an endophytic alkaloid. 1. Animal physiology and metabolism

“…A series of in vivo alkaloid-balance studies all came to similar conclusions regarding the conversion of ergovaline to lysergic acid in geldings (Schultz et al 2006), wethers (De Lorme et al 2007) and steers (Merrill et al 2007). Specifically, these studies all reported intake concentrations of ergovaline and lysergic acid and concentrations of these compounds in the urine and faeces.…”

“…In that study (Goff et al 2012), the rates of ergovaline released from vegetative tissues would closely approximate reported dosage rates. In another in vitro rumen-fermentation study, only 60% of total ergot alkaloids were released (Stuedemann et al 1998) and an in vivo study with sheep reported a 64% (De Lorme et al 2007) apparent release of ergovaline from digested plant tissues. Differences between the in vitro studies of Goff et al (2012) and Stuedemann et al (1998) may related to differences in in vitro digestion methodology.…”

“…Differences between the in vitro studies of Goff et al (2012) and Stuedemann et al (1998) may related to differences in in vitro digestion methodology. The difference between the in vivo study of De Lorme et al (2007) and the study reported by Goff et al (2012) may be attributed to differences and particle sizes between in vivo and in vitro, and the smaller size achieved when grinding substrate for in vitro fermentation than with mastication and comminution by the animal (De Lorme et al (2007) fed a mixture of endophyte-infected straw (0.35 mg/kg DM ergovaline) and ground seed (3.30 mg/kg DM) formulated to achieve 0.610 mg/kg DM ergovaline in the diet) that lead to a greater release of ergovaline during digestion. This further indicates that ergovaline release from an intact seed may not be as complete as that from a ground seed.…”

Recent Investigations of Ergot Alkaloids Incorporated into Plant and/or Animal Systems

“…In addition to plantfungus-environment interaction variations, the grazing animal will also influence alkaloid production. Consumption of ergot alkaloid-containing feedstuff will interact with the gut microbiome prior to the animal and likely influences the level of exposure to ergot alkaloids by the animal (De Lorme et al, 2007;Ayers et al, 2009). Biological activity of ergot alkaloids absorbed by the animal is defined by the structural similarity of these compounds to biogenic amines (Berde, 1980) allowing ergot alkaloids to interact with serotonergic, adrenergic, and dopaminergic receptors that exist in varying populations throughout the body and results in variable negative effects.…”