Thermoregulatory Response of Dairy Cows Fed Ergotized Barley during Summer Heat Stress

Abstract

Claviceps purpurea infects the seed heads of cereal grains and grasses and produces ergopeptine alkaloids that cause hyperthermia and agalactia in cattle during periods of heat stress. A field experiment was undertaken to examine the effects of ergopeptine alkaloids found in barley on thermal status of dairy cattle during periods of heat stress. Production end points were also measured to identify the effect of the change in thermal status. Contaminated barley screenings containing known levels of ergopeptine alkaloids were fed to lactating Holstein cattle (10 microg total ergopeptine alkaloids/kg BW/day) for 10 days during summer heat stress. Air temperature increased 14.4 C during the first 8 days of treatment and then declined the same during the last 2 days. Extreme daily values for rectal temperature and respiration rate, using averages of all animals, showed maximum increases of 2.3 C and 56.8 breaths/minute, respectively, during this period. Group afternoon milk production decreased 2 kg/day during the heat stress period, with no measurable change in feed intake. A greater level of hyperthermia occurred in cattle consuming the diet with ergopeptine alkaloids, with only marginal symptoms of ergot toxicosis reflected in feed intake and milk production. Therefore, the ergopeptine alkaloid dose used in this study represents a level for minimal induction of the ergot toxicity response.

Effects of different levels of ergot in concentrates on the growing and slaughtering performance of bulls and on carry-over into edible tissue

“…But due to the observed marginal symptoms of ergot toxicosis reflected in body temperature and milk production, the author suggested this alkaloid dose as a level for minimal induction of the ergot toxicity response (AlTamimi et al 2003). Considering that Al-Tamimi et al (2003) used ergotized barley, which probably also contained ergometrine and its isomere, the only alkaloids analysed in the current study, which do not belong to the ergopeptine group, the total alkaloid administration might have been a little higher. The current study revealed a percentage of 93% ergopeptine alkaloids of the total alkaloid amount ( Table I).…”

“…As the average total daily alkaloid exposure in the current experiment did not exceed 9 mg per kg LW (8.4 mg ergopeptine alkaloids per kg LW), it might have been low enough to be completely tolerated by the animals, but following Al-Tamimi et al (2003) this dose would then be very close to the no-effect level.…”

“…Al-Tamimi et al (2003) tested the thermoregulatory response of dairy cows fed ergotized barley. A ten-day administration of 10 mg ergopeptine alkaloids per kg LW (only ergopeptine alkaloids have been analysed) to Holstein cows did not cause significant effects on DMI.…”

Claviceps purpurea e Bipolaris sp. como causa de ergotismo em bovinos no estado de Santa Catarina

“…Na reprodução experimental, o quadro clínico de hipertermia ocorreu nos períodos mais quentes do dia, e está de acordo com o descrito para a intoxicação por C. purpurea (Al-Tamimi et al 2003). Já o Bovino 5 que ingeriu as inflorescências infectadas nos dias mais amenos não manifestou estes sinais.…”

Human and cattle ergotism since 1900

“…In August 1996, there was an outbreak in the United States. Several cattle herds in Northeast Iowa and Southwest Wisconsin suffered from hyperthermic ergotism after eating infected barley (Al-Tamimi et al, 2003).…”