Effects of Cold-Dry (Harmattan) and Hot-Dry Seasons on Daily Rhythms of Rectal and Body Surface Temperatures in Sheep and Goats in a Natural Tropical Environment

Abstract

Studies on daily rhythmicity in livestock under natural conditions are limited, and there is mounting evidence that rhythm patterns differ between chronobiological studies conducted in the laboratory and studies conducted under pronounced natural seasonality. Here, we investigated the influence of cold-dry (harmattan) and hot-dry seasons on daily rhythmicity of rectal (RT) and body surface temperatures (BST) in indigenous sheep and goats under natural light-dark cycles. The RT and BST of the animals, and the ambient temperature (AT) and relative humidity (RH) inside the pen, were measured every three hours for a period of two days, twice on separate days during the hot-dry and the harmattan seasons, respectively. The AT and RH had minimum values of 16°C and 15% recorded during the harmattan and maximum values of 32°C and 46% recorded during the hot-dry season, respectively. A trigonometric statistical model was applied to characterize the main rhythmic parameters according to the single cosinor procedure. The result showed that RT and BST exhibited different degrees of daily rhythmicity, and their oscillatory patterns differed with the seasons (larger amplitude during the harmattan season than during the hot-dry season). The goats displayed greater (p < 0.05) amplitude of BST than the sheep in all seasons. The acrophases were restricted to the light phase of the light-dark cycle. The mesor of RT in goats was not affected by the season, but mesors of BST in both species were significantly higher (p < 0.05) during the hot-dry than the harmattan season. The goats had a more robust RT rhythm (70%) as compared to the sheep (56%). Overall, the results demonstrated that seasonal changes influenced considerably the daily rhythmicity of RT and BST in sheep and goats under natural light-dark cycle. Awareness of these changes may be useful in the improvement of diagnosis, treatment and prevention of diseases, and welfare and productivity of sheep and goats under cold-dry and hot-dry conditions.

Variations in Platelet Count and Total Protein in Relation to Differences in Sex, Age, Breed and Reproductive Status of Goats during the Cold-Dry Season (Harmattan)

“…17 In agreement with previous observation, 1 this suggests that the goats may have suffered from hypothermia during the morning hours of the cold-dry season.…”

“…1,2 Hypothermia has been shown to cause thrombocytopenia, slowing down of coagulation enzymes, disordered fibrinolysis, and disruption of platelet function; and thus, may negatively affect the hemostasis. 3,4 This may pose a challenge to haemostasis during parturition and injury which are characterised by excessive bleeding.…”

Diurnal rhythms of heart and respiratory rates in donkeys of different age groups during the cold-dry and hot-dry seasons in a tropical savannah

“…). Extreme environmental temperature affects daily rhythms of physiological functions, which distort the circadian clock, and invariably compromise production and welfare of the animals (Minka and Ayo ). Variations in HR reflect the balance between sympathetic and parasympathetic tones and are used as an indicator of stress response in animals (Piccione et al.…”

“…The HR and RespR are important physiologic indices in determining the responses of donkeys to changes in thermal environmental conditions, and variations in the parameters are indicative of adjustments to maintain homeostasis (Homma and Masaoka 2008;Seebacher et al 2015). Extreme environmental temperature affects daily rhythms of physiological functions, which distort the circadian clock, and invariably compromise production and welfare of the animals (Minka and Ayo 2016). Variations in HR reflect the balance between sympathetic and parasympathetic tones and are used as an indicator of stress response in animals (Piccione et al 2009;Ohmura et al 2012;Reyes del Paso et al 2013).…”

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“…The skin temperature could also be elevated due to solar radiation as skin temperature has been shown to be directly related to solar radiation levels. 13 Shown that body temperature of goats was significantly (p<0.05) higher than that of the sheep in all the season. the homoeothermic animals initially react to cold stress by enhancing the thermoregulatory mechanism, such as increase in respiration rate.…”