Perennial Ryegrass Alkaloids Increase Respiration Rate and Decrease Plasma Prolactin in Merino Sheep under Both Thermoneutral and Mild Heat Conditions
A study was undertaken to determine the effects of feeding two levels of perennial ryegrass alkaloids (nil vs. moderate) under two climatic conditions. Alkaloids were fed via endophyte-infected perennial ryegrass seed and hay. Twenty-four Merino ewe weaners (six months, initial BW 32 ± 1.7...
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| Format: | Article |
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MDPI AG
2019-08-01
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| Series: | Toxins |
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| Online Access: | https://www.mdpi.com/2072-6651/11/8/479 |
| _version_ | 1811183906014101504 |
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| author | Michelle L. E. Henry Stuart Kemp Iain J. Clarke Frank R. Dunshea Brian J. Leury |
| author_facet | Michelle L. E. Henry Stuart Kemp Iain J. Clarke Frank R. Dunshea Brian J. Leury |
| author_sort | Michelle L. E. Henry |
| collection | DOAJ |
| description | A study was undertaken to determine the effects of feeding two levels of perennial ryegrass alkaloids (nil vs. moderate) under two climatic conditions. Alkaloids were fed via endophyte-infected perennial ryegrass seed and hay. Twenty-four Merino ewe weaners (six months, initial BW 32 ± 1.7 kg) were used in a study that lasted for 21 days after 14 days of adaptation. Sheep were fed either a control or alkaloid (Alk, 110 μg/kg LW ergovaline and 75 μg/kg LW lolitrem B) supplemented diet. Sheep were exposed to either constant thermoneutral (TN, 21−22 °C, 49% RH) or mildly heated (HS, 33 °C 1000−1500 h, 28% relative humidity) conditions. Dietary Alk and HS reduced dry matter intake (DMI) (<i>p</i> < 0.001, <i>p</i> = 0.02, respectively) with the combination of both reducing DMI by 42%. Reductions in DMI resulted in a lower daily gain in the Alk treatment (<i>p</i> < 0.001). Feed digestibility was reduced in the combined treatment (<i>p</i> = 0.03). Rectal temperature, respiration rate, and skin temperature increased in the Alk treatment. Plasma prolactin concentrations were decreased by Alk and increased by mild HS. The data indicate that production is compromised in the presence of Alk and mild HS, with this effect being exacerbated by a combination of both. |
| first_indexed | 2024-04-11T13:04:40Z |
| format | Article |
| id | doaj.art-1e9815c49e854dbb8590e59f53332914 |
| institution | Directory Open Access Journal |
| issn | 2072-6651 |
| language | English |
| last_indexed | 2024-04-11T13:04:40Z |
| publishDate | 2019-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Toxins |
| spelling | doaj.art-1e9815c49e854dbb8590e59f533329142022-12-22T04:22:48ZengMDPI AGToxins2072-66512019-08-0111847910.3390/toxins11080479toxins11080479Perennial Ryegrass Alkaloids Increase Respiration Rate and Decrease Plasma Prolactin in Merino Sheep under Both Thermoneutral and Mild Heat ConditionsMichelle L. E. Henry0Stuart Kemp1Iain J. Clarke2Frank R. Dunshea3Brian J. Leury4Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC 3010, AustraliaPastureWise Pty. Ltd., 1485 Bamganie Rd, Cargerie, VIC 3334, AustraliaFaculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC 3010, AustraliaFaculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC 3010, AustraliaFaculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC 3010, AustraliaA study was undertaken to determine the effects of feeding two levels of perennial ryegrass alkaloids (nil vs. moderate) under two climatic conditions. Alkaloids were fed via endophyte-infected perennial ryegrass seed and hay. Twenty-four Merino ewe weaners (six months, initial BW 32 ± 1.7 kg) were used in a study that lasted for 21 days after 14 days of adaptation. Sheep were fed either a control or alkaloid (Alk, 110 μg/kg LW ergovaline and 75 μg/kg LW lolitrem B) supplemented diet. Sheep were exposed to either constant thermoneutral (TN, 21−22 °C, 49% RH) or mildly heated (HS, 33 °C 1000−1500 h, 28% relative humidity) conditions. Dietary Alk and HS reduced dry matter intake (DMI) (<i>p</i> < 0.001, <i>p</i> = 0.02, respectively) with the combination of both reducing DMI by 42%. Reductions in DMI resulted in a lower daily gain in the Alk treatment (<i>p</i> < 0.001). Feed digestibility was reduced in the combined treatment (<i>p</i> = 0.03). Rectal temperature, respiration rate, and skin temperature increased in the Alk treatment. Plasma prolactin concentrations were decreased by Alk and increased by mild HS. The data indicate that production is compromised in the presence of Alk and mild HS, with this effect being exacerbated by a combination of both.https://www.mdpi.com/2072-6651/11/8/479sheepheat stressergovalinelolitrem Bproductionphysiologystaggers |
| spellingShingle | Michelle L. E. Henry Stuart Kemp Iain J. Clarke Frank R. Dunshea Brian J. Leury Perennial Ryegrass Alkaloids Increase Respiration Rate and Decrease Plasma Prolactin in Merino Sheep under Both Thermoneutral and Mild Heat Conditions Toxins sheep heat stress ergovaline lolitrem B production physiology staggers |
| title | Perennial Ryegrass Alkaloids Increase Respiration Rate and Decrease Plasma Prolactin in Merino Sheep under Both Thermoneutral and Mild Heat Conditions |
| title_full | Perennial Ryegrass Alkaloids Increase Respiration Rate and Decrease Plasma Prolactin in Merino Sheep under Both Thermoneutral and Mild Heat Conditions |
| title_fullStr | Perennial Ryegrass Alkaloids Increase Respiration Rate and Decrease Plasma Prolactin in Merino Sheep under Both Thermoneutral and Mild Heat Conditions |
| title_full_unstemmed | Perennial Ryegrass Alkaloids Increase Respiration Rate and Decrease Plasma Prolactin in Merino Sheep under Both Thermoneutral and Mild Heat Conditions |
| title_short | Perennial Ryegrass Alkaloids Increase Respiration Rate and Decrease Plasma Prolactin in Merino Sheep under Both Thermoneutral and Mild Heat Conditions |
| title_sort | perennial ryegrass alkaloids increase respiration rate and decrease plasma prolactin in merino sheep under both thermoneutral and mild heat conditions |
| topic | sheep heat stress ergovaline lolitrem B production physiology staggers |
| url | https://www.mdpi.com/2072-6651/11/8/479 |
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