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Fonsêca VFC, Dos Santos JDC, Saraiva EP, Xavier Neta GC, Morais LKC, Bícego KC, Pereira WE, Pimenta Filho EC, Moura GAB, Sejian V, Fuller A. Do newborn lambs with black and white hair-coats in an equatorial semi-arid environment maintain homeothermy? INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2024:10.1007/s00484-024-02710-9. [PMID: 38884796 DOI: 10.1007/s00484-024-02710-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 04/16/2024] [Accepted: 05/18/2024] [Indexed: 06/18/2024]
Abstract
We assessed newborn lambs from two hair-coat sheep breeds, the black Santa Ines (n = 29) and white Dorper (n = 26), to determine how they behaviourally and physiologically respond to the prevailing thermal conditions in an equatorial semi-arid environment. Measurements of hair-coat surface temperature, rectal temperature and the lambs' exposure to sun were recorded across the first 24 h of life every hour, after the lambs had received colostrum. Lambs and ewes were kept in a lambing pen and could freely move between a shaded area or be exposed to sun. During the study period, the air temperature ranged between 20 ºC and 34 ºC. When exposed to sun, lambs and ewes could experience as much as 1200 W m-2 of solar irradiance. Santa Ines lambs exhibited higher (highest density interval at 95%, HDI) hair-coat surface temperatures than did Dorper lambs. Overall, both Santa Ines and Dorper lambs sustained homeothermy, with a mean rectal temperature ranging from 38.7 ºC to 39.1 ºC between night and daytime phase, and a mean amplitude of ~ 0.8 ºC. Nevertheless, from 10:00 to 15:00, some lambs were found to be moderately hyperthermic. Five Santa Ines and three Dorper lambs had rectal temperatures above 40 ºC, and one Santa Ines lamb, while exposed to sun, had a rectal temperature of 41.3 ºC. Over this time period, lambs were more likely to move to shade (HDI at 95%). From 00:00 to 06:00, despite the air temperature being lower than the hair-coat surface, favouring high rates of sensible heat loss to the environment, no lamb exhibited signs of hypothermia (rectal temperature < 37.5 ºC). In conclusion, haired newborn lambs coped well with high levels of radiant heat during the daytime and lower temperatures at night. However, providing access to shade during the daytime is important to improve the welfare of newborn lambs delivered in equatorial semi-arid regions.
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Affiliation(s)
- V F C Fonsêca
- Laboratory of Animal Biometeorology, São Paulo State University, Jaboticabal, Brazil.
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa.
| | - J D C Dos Santos
- Animal Biometeorology and Ethology Group, Department of Animal Science, Federal University of Paraiba, Areia, Brazil
| | - E P Saraiva
- Animal Biometeorology and Ethology Group, Department of Animal Science, Federal University of Paraiba, Areia, Brazil
| | - G C Xavier Neta
- Department of Animal Morphology and Physiology, São Paulo State University, Jaboticabal, SP, Brazil
| | - L K C Morais
- Animal Biometeorology and Ethology Group, Department of Animal Science, Federal University of Paraiba, Areia, Brazil
| | - K C Bícego
- Department of Animal Morphology and Physiology, São Paulo State University, Jaboticabal, SP, Brazil
| | - W E Pereira
- Department of Fundamental and Social Sciences, Federal University of Paraíba, Areia, Paraíba, Brazil
| | - E C Pimenta Filho
- Department of Fundamental and Social Sciences, Federal University of Paraíba, Areia, Paraíba, Brazil
| | - G A B Moura
- Laboratory of Animal Biometeorology, São Paulo State University, Jaboticabal, Brazil
| | - V Sejian
- Rajiv Gandhi Institute of Veterinary Education and Research Puducherry, Puducherry, India
| | - A Fuller
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa
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The effects of litter size, sex, age, body weight, dam age and genetic selection for cold resistance on the physiological responses to cold exposure of scottish blackface lambs in a progressively cooled water bath. ACTA ACUST UNITED AC 2010. [DOI: 10.1017/s0003356100002968] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
ABSTRACTThe resistance to body cooling of 594 newborn Scottish Blackface lambs was measured in a water bath during a programme of upwards and downwards genetic selection. Cold resistance was defined as the time taken for rectal temperature to fall to 35°C in the water bath.Upwards selection produced increased cold resistance which was genetically associated with increased skin thickness, increased total body insulation and greater persistence of high metabolic rate during cold exposure. The first two correlated responses to selection were more pronounced in twins than in singles.High cold resistance was phenotypically, but not genetically, associated with greater body weight, increased coat depth and higher levels of cold-induced metabolic rate (heat production). Single lambs showed higher weight-adjusted metabolic rates and higher cold resistance than twins. Singles recovered from hypothermia faster than twins in the low selection line only.Female lambs showed higher metabolic rate (whether weight-adjusted or not) and greater total body insulation than males. Their greater cold resistance was not quite significant. Increasing age (range 0·3 to 36 h) was associated with a small but significant decline in cold resistance.Thermoneutral metabolic rate was proportional to body surface area, whereas peak metabolic rate was proportional to body weight such that peak metabolic rate per unit body weight was independent of changes in body weight. These findings are discussed in relation to lamb survival.
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Abstract
The vagus nerve may indirectly influence thermoregulation by modulation of energy balance: its afferent fibers convey signals that represent information on feeding state, resulting in either depression or stimulation of metabolic processes. A regulated metabolic depression can be detected in the background of fasting-induced hypometabolism and hypothermia. In its development (besides humoral signals) vagally transmitted neural signals of gastrointestinal and hepatoportal origin are important. These signals are related to hunger, to decrease of mechanical/chemical stimuli from the gut, to decline of blood glucose; they alter discharge rates of vagal afferents and activity of the nucleus of the solitary tract, eliciting inhibition of metabolic rate and enhancement of food intake. In this hunger-related metabolic inhibition the nucleus of the solitary tract is in interaction with hypothalamic nuclei, that contribute to neuropeptide changes characterized by high neuropeptide Y activity (with energy-conserving type of regulation) and depressed cholecystokinin and corticotropin releasing hormone activities (with depressed energy-expenditure). In postalimentary states the hypermetabolism and hyperthermia are due to opposite changes in metabolic regulation. Satiety-related stimulatory signals of abdominal origin, transmitted via hepatic vagal afferents to the nucleus of the solitary tract, contribute to enhancement of sympathetic activity and stress-responsiveness, leading to hypermetabolism and hyperthermia. Depressed neuropeptide Y release and enhanced cholecystokinin and corticotropin releasing hormone activities participate in the central regulatory changes, and in the high energy-expenditure. The biological role of these vagal functions is not directly the regulation of body temperature, rather the regulation of energy balance and energy content in the body.
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Affiliation(s)
- M Székely
- Department of Pathophysiology, University of Pécs, Faculty of Medicine, Hungary.
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Berthon D, Herpin P, Bertin R, De Marco F, le Dividich J. Metabolic changes associated with sustained 48-hr shivering thermogenesis in the newborn pig. Comp Biochem Physiol B Biochem Mol Biol 1996; 114:327-35. [PMID: 8840509 DOI: 10.1016/0305-0491(96)00044-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Metabolic changes associated with sustained 48-hr shivering thermogenesis were studied in piglets maintained at 34 (thermoneutrality) or 25 degrees C (cold) between 6 and 54 hr of life. Despite their high shivering activity and elevated heat production, cold-exposed piglets exhibited a slightly lower rectal temperature than thermoneutral animals (-1.1 degrees C; P < 0.01) at the end of the treatment. The enhancement of heat production and shivering activity were associated with a decrease in muscle glycogen (-47%; P < 0.05) and total lipid content (-23%; P < 0.05), a reduction of blood lactate levels (P < 0.05) and an enhancement of muscle cytochrome oxidase activity (+20%; P < 0.05) which suggests that muscle oxidative potential was increased by cold exposure. Potential for capturing lipids (lipoprotein lipase activity) was also higher in the red rhomboideus muscle (+71%; P < 0.01) and lower in adipose tissue (-58%; P < 0.01) of the cold-exposed piglets. Measurements performed at the mitochondrial level show no changes in rhomboideus muscle, but respiratory capacities (state IV and FCCP-stimulated respiration) and intermyofibrillar mitochondria oxidative and phosphorylative (creatine kinase activity) capacities were enhanced in longissimus dorsi muscle (P < 0.05). These changes may contribute to provide muscles with nonlimiting amount of readily oxidable substrates and ATP necessary for shivering thermogenesis. A rise in plasma norepinephrine levels was also observed during the second day of cold exposure (P < 0.05).
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Affiliation(s)
- D Berthon
- INRA, Station de Recherches Porcines, St Gilles, France
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Laburn HP, Goelst K, Mitchell D. Body temperatures of lambs and their mothers measured by radio-telemetry during parturition. EXPERIENTIA 1994; 50:708-11. [PMID: 8070529 DOI: 10.1007/bf01919367] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Using temperature-sensitive radio-telemeters chronically implanted in the abdomens of 8 fetal lambs and their mothers, we measured body temperature changes induced by parturition. Maternal body temperature rose at 0.70 +/- 0.06 degrees C/hour (mean +/- SEM) in the final stages of labour. Fetal body temperature also rose, but at a significantly lower rate, 0.45 +/- 0.06 degrees C/hour (p < 0.05). The fetus appears to be protected from excessive hyperthermia during the birth process.
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Affiliation(s)
- H P Laburn
- Department of Physiology, University of the Witwatersrand Medical School, Parktown, South Africa
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