Circadian and circannual rhythms of T3 and T4 secretions in Polwarth–Ideal rams

Souza, M.S.S.; Bicudo, Sony Dimas; Uribe-Velásquez, Luis Fernando; Ramos, A. A.

doi:10.1016/s0921-4488(02)00103-7

Cited by 20 publications

(16 citation statements)

References 6 publications

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“…Blood TH concentrations were high in spring (increasing daylength) and low in autumn (decreasing daylength), which was not fully explained by the changes in environmental temperature (Figure 2; Buys et al, 1990;Todini et al, 1992; McMillen, 1995: Clariget et al, 1998;Rhind et al, 2000;Taha et al, 2000;Villar et al, 2000a;Merchant and Riach, 2002;Souza et al, 2002; Blaszczyk et al, 2004;Zamiri and Khodaei, 2005;Menegatos et al, 2006;Todini et al, 2006). It seems that when the temperature ranges are not extreme (mild climate, indoor housing, shelter in the night time), the effect of photoperiod and season-dependent TH profiles (mainly related to the daylength changes) are present.…”

Section: Season Effectsmentioning

confidence: 98%

“…In winter, T3 and T4 concentrations reached maximal levels in early morning, probably because of a delayed response to cold stress to which the animals were exposed by night; furthermore, the circadian variations in winter decreased with the increase in wool length (Salem et al, 1991). Combining the results obtained from samplings carried out every 2 months for 1 year, rams showed the highest TH concentrations during the afternoon and the lowest in the early morning (Souza et al, 2002). …”

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confidence: 93%

“…In the Sahel desert, plasma T3 and T4 levels did not change significantly from the beginning of the cool season (December) until the end of the dry warm season (May), but a highly significant rise of both hormones was observed at the onset of the humid warm season (June) (Assane and Sere, 1990). It can be supposed that an enhanced thyroid activity during the humid warm season in such environments is functional for the animals facing the increased availability of food (quantity and quality), following the seasons characterised by food shortage.Blood TH concentrations were high in spring (increasing daylength) and low in autumn (decreasing daylength), which was not fully explained by the changes in environmental temperature (Figure 2; Buys et al, 1990;Todini et al, 1992; McMillen, 1995: Clariget et al, 1998;Rhind et al, 2000;Taha et al, 2000;Villar et al, 2000a;Merchant and Riach, 2002;Souza et al, 2002; Blaszczyk et al, 2004;Zamiri and Khodaei, 2005;Menegatos et al, 2006;Todini et al, 2006). It seems that when the temperature ranges are not extreme (mild climate, indoor housing, shelter in the night time), the effect of photoperiod and season-dependent TH profiles (mainly related to the daylength changes) are present.…”

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confidence: 98%

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Thyroid hormones in small ruminants: effects of endogenous, environmental and nutritional factors

Todini

2007

Animal

197

142

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Appropriate thyroid gland function and thyroid hormone activity are considered crucial to sustain the productive performance in domestic animals (growth, milk or hair fibre production). Changes of blood thyroid hormone concentrations are an indirect measure of the changes in thyroid gland activity and circulating thyroid hormones can be considered as indicators of the metabolic and nutritional status of the animals. Thyroid hormones play a pivotal role in the mechanisms permitting the animals to live and breed in the surrounding environment. Variations in hormone bioactivity allow the animals to adapt their metabolic balance to different environmental conditions, changes in nutrient requirements and availability, and to homeorhetic changes during different physiological stages. This is particularly important in the free-ranging and grazing animals, such as traditionally reared small ruminants, whose main physiological functions (feed intake, reproduction, hair growth) are markedly seasonal. Many investigations dealt with the involvement of thyroid hormones in the expression of endogenous seasonal rhythms, such as reproduction and hair growth cycles in fibre-producing (wool, mohair, cashmere) sheep and goats. Important knowledge about the pattern of thyroid hormone metabolism and their role in ontogenetic development has been obtained from studies in the ovine foetus and in the newborn. Many endogenous (breed, age, gender, physiological state) and environmental factors (climate, season, with a primary role of nutrition) are able to affect thyroid activity and hormone concentrations in blood, acting at the level of hypothalamus, pituitary and/or thyroid gland, as well as on peripheral monodeiodination. Knowledge on such topics mirror physiological changes and possibly allows the monitoring and manipulation of thyroid physiology, in order to improve animal health, welfare and production.Keywords: goats, nutrition, seasons, sheep, thyroid hormones IntroductionAppropriate thyroid gland function and activity of thyroid hormones (TH) are considered crucial to sustain the productive performance in domestic animals (growth, milk, hair fibre production) and circulating TH can be considered as indicators of the metabolic and nutritional status of the animals (Riis and Madsen, 1985;Todini et al., 2007). Changes of blood TH concentrations are an indirect measure of the changes in thyroid gland activity. Many papers report marked seasonal variation in thyroid activity and in blood TH concentration. These hormone variations are particularly important in the free-ranging and grazing animals, whose main physiological functions (feed intake, reproduction, hair growth) are markedly seasonal. This is the case of small ruminants traditionally reared. Such variations in hormone concentration, in fact, allow the animals to adapt their metabolic balance to different environmental conditions, variations in nutrient requirements and availability, and to homeoretic changes during different physiological stages.The present paper aims to re...

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Section: Season Effectsmentioning

confidence: 98%

mentioning

confidence: 93%

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confidence: 98%

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Thyroid hormones in small ruminants: effects of endogenous, environmental and nutritional factors

Todini

2007

Animal

197

142

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“…2). This T4 circadian rhythm is present in other ruminant [Souza et al, 2002] and nonruminant [Selmaoui et al, 1997;Oki and Atkinson, 2004] species.…”

Section: Discussionmentioning

confidence: 70%

Plasma concentrations of thyroxine in dairy cows exposed to 60 Hz electric and magnetic fields

Burchard

Nguyen

Rodríguez

2006

Bioelectromagnetics

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Two experiments were carried out to assess the effects of electric and magnetic fields (EMF) on blood thyroxine (T4) in dairy cattle. In experiment 1, 16 lactating pregnant Holstein cows were exposed to 10 kV/m, 30 microTesla (microT) EMF. The animals were divided into two groups of eight animals each. Each group was exposed to EMF according to one of two treatment sequences of three periods of 28 days each. Sequence 1 was EMF OFF-ON-OFF and sequence 2 was EMF ON-OFF-ON. During the last day of each treatment period, blood samples were collected every 4 h for 24 h to estimate T4 plasma concentrations. In experiment 2, 16 nonlactating, nonpregnant, multiparous Holsteins were exposed to 10 kV/m, 30 microT EMF. The animals were divided into two groups of eight animals each. Each group was exposed to EMF according to one of the two treatment sequences described above, except that each period amounted to the number of days corresponding to one estrous cycle. During treatment, blood samples were collected every other day for T4 analysis. In both experiments, the light cycle emulated a short photoperiod (8 h light/16 h dark). During the ON periods, the animals were exposed to EMF for 16 h, 8 h of the light period plus the first 8 h of during the dark period. In experiment 1, exposed animals did not have any change in T4 plasma concentrations due to treatment (P = .0968), but, the time of sample collection revealed a significant difference (P = .0012). In experiment 2, the effect of period (P = .0009) and the treatment by days interaction (P = .0003) were statistically significant. We conclude that a worst case scenario exposure of dairy cattle to 10 kV/m, 30 microT EMF influences, in a moderate fashion, the blood levels of thyroxine.

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“…Godfrey et al (1991) observed significant (P < 0.05) increase in thyroid levels of Brahman calves after birth when they were exposed to cold treatment. Similarly, Souza et al (2002) also reported increased thyroid levels in rams exposed to cold weather.…”

Section: Cortisolmentioning

confidence: 80%

Role of Infrared lamps in cold stress alleviation during winter in Murrah calves

Bhat

Bhushan

Kumar

et al. 2016

IJAR

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The main aim of this study was to determine the role of Infrared lamps in cold stress alleviation during winter in Murrah calves. Ten newborn calves were randomly divided into two groups (G 1 and G 2 ) of five each. The calves of G 1 were provided with no additional protection; however calves of G 2 were protected against cold weather by using Infrared lamps. The body weight (kg) of calves was recorded at weekly interval. The blood samples collected at fortnightly interval were analyzed for Packed Cell volume (PCV, %), hemoglobin (Hb, g/dl), Total Serum Protein (TSP, g/l), albumin (g/l), globulin (g/l) and albumin globulin (A:G) ratio and hormones viz., triiodothyronine (T 3 , ng/ml), thyroxine (T 4 , ng/ml) and cortisol (ng/ml). The total body weight gain and average daily gain (ADG) was significantly (P<0.01) higher in G 2 as compared to G 1 . The PCV values were significantly (P<0.05) higher on day 15 and day 45 in G 1 than G 2 . The albumin and A:G Ratio were significantly (P<0.05) higher on day 60 and 45, respectively in G 1 than G 2 . The cortisol levels were higher in G 1 than G 2 and differences were highly significant (P<0.01) on 15 th day and significant (P<0.05) on 45 th day. Significantly (P<0.01) higher values of T 3 and T 4 were observed on 15 th and 45 th day in G 1 as compared to G 2 . On the basis of the results, it may be concluded that Infrared lamps can be effectively used to protect newborn calves from adverse conditions of winter and to improve their body growth performance.

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Circadian and circannual rhythms of T3 and T4 secretions in Polwarth–Ideal rams

Cited by 20 publications

References 6 publications

Thyroid hormones in small ruminants: effects of endogenous, environmental and nutritional factors

Thyroid hormones in small ruminants: effects of endogenous, environmental and nutritional factors

Plasma concentrations of thyroxine in dairy cows exposed to 60 Hz electric and magnetic fields

Role of Infrared lamps in cold stress alleviation during winter in Murrah calves

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