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Effect of sorghum ergot (Claviceps africana) on the performance of steers (Bos taurus) in a feedlot.

Blaney, B.J. and McLennan, S.R. and Kidd, J.F. and Connell, J.A. and McKenzie, R.A. and Downing, J.A. (2011) Effect of sorghum ergot (Claviceps africana) on the performance of steers (Bos taurus) in a feedlot. Animal Production Science, 51 (2). pp. 156-166.

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Article Link(s): http://dx.doi.org/10.1071/AN10086

Publisher URL: http://www.publish.csiro.au

Abstract

The effect of ergot (Claviceps africana) in naturally infected sorghum was assessed in feedlot rations. Thirty-two Hereford steers (Bos taurus) in individual pens with access to shade were adapted to feedlot conditions and then offered one of four rations containing 0, 4.4, 8.8 or 17.6 mg/kg of ergot alkaloids (84% dihydroergosine, 10% dihydroelymoclavine and 6% festuclavine), equivalent to ~0, 10, 20 or 40 g/kg ergot (sclerotia/sphacelia) in the rations. These rations were withdrawn at noon on the second day because of severe hyperthermia and almost complete feed refusal in ergot-fed steers. After recovery on ergot-free rations for 5 days, treatment groups were incrementally introduced, over a further 3–12 days, to rations containing 0, 1.1, 2.2 or 4.4 mg/kg of alkaloids (~0, 2.5, 5 or 10 g/kg ergot, respectively). Relative exposure to ergot was maintained, so that the zero- (control), low-, medium- and high-ergot groups remained so. Steers were individually fed ad libitum, and water was freely available. Steers in all ergot-fed groups had significantly elevated rectal temperatures at 0800–1000 hours, even when the temperature–humidity index was only moderate (~70), and displayed other signs of hyperthermia (increased respiration rate, mouth breathing, excessive salivation and urination), as the temperature–humidity index increased to 73–79 during the day. Plasma prolactin was significantly reduced in ergot-fed groups. Voluntary feed intakes (liveweight basis) of the ergot-fed groups were significantly reduced, averaging 94, 86 and 86%, respectively, of the feed intakes of the control group. Hair coats were rough. While the control steers grew from a mean initial liveweight of 275 kg to a suitable slaughter weight of 455 kg in 17 weeks (growth rate 1.45 kg/day), ergot-fed groups gained only 0.77–1.10 kg/day and took at least 5 weeks longer to reach the slaughter weight, despite removal of ergot at the same time as control steers were sent to slaughter. Sorghum ergot, even at low concentrations (1.1 mg alkaloids/kg feed) is severely detrimental to the performance of steers in the feedlot.

Item Type:Article
Corporate Creators:DEEDI
Additional Information:© CSIRO
Keywords:Fungus; mycotoxin; sorghum ergot (Claviceps Africana); hereford steers (Bos taurus); hyperthermia; feedlot rations.
Subjects:Plant pests and diseases > Individual or types of plants or trees > Sorghum
Animal culture > Feeds and feeding. Animal nutrition
Veterinary medicine > Diseases of special classes of animals > Cattle
Deposited On:30 Mar 2011 00:33
Last Modified:20 Jun 2011 23:25

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