The aim of this review was to understand the role of physiological, hematological, biochemical and hormonal variables of the blood of goats raised in adverse environments. Scientific work in recent years has allowed for the evaluation of how goats of various breeds respond to edaphoclimatic effects to maintain homeothermy according to adaptability to the environment. The exposure of goats to heat stress causes changes in the physiological functions with impact on production and productivity of the animals. There is evidence that the central nervous system is sensitive to temperature changes, and some cells are agiler in the cold than in heat. In conclusion, we say that regardless of the breed, the raising environment and its climatic variables can trigger physiological, biochemical, hematological and hormonal alterations that result in a reduction of the heat production for maintenance of homeothermy. All these changes have a substantial impact on production and productivity.

This study investigated the effect of season on the endocrine and adaptive profiles of a Brazilian Creole goat population in a semi-arid region of Brazil during the dry and the rainy season. We considered physiological, morphological, biochemical, haematological, hormonal and anatomical profiles. The experiment used 80 adult goats (2-to 5-year-old) and lactating (160 ± 14 days of lactation length) goats, with an average daily milk yield of 500.9 ± 13 g. Physiological parameters (rectal temperature, RT; respiratory rate, RR; heart rate, HR; skin temperature, ST) were high (p < .05) in the afternoon in both seasons. There was a significant effect of season (p < .05) on anatomical parameters (hair diameter, HD; hair length, HL; coat thickness, CT). Haematological, biochemical and hormonal parameters were also significantly affected by season (p < .05). We measured the biochemical and hormonal characteristics changes during different seasons; metabolism was reduced during heat stress and accelerated during cold stress. These hormones facilitate the physiological parameters involved in the adaptation process. Our results confirm that the adaptive capacity of the animals cannot be described solely by RT and RR.ARTICLE HISTORY

RESUMO:Esta pesquisa teve o objetivo de determinar os índices de conforto térmico em instalações para ovinos, analisar os parâmetros fisiológicos e o gradiente térmico de quatro grupos genéticos, na região semiárida paraibana. Foram utilizados 40 animais, dez por grupo genético, que foram: Cariri, Morada Nova, Barriga Negra e Cara Curta, todas fêmeas, alojadas aleatoriamente em quatro apriscos. Os índices ambientais dentro das instalações, principalmente das 11 às 15 h, ficaram acima da zona de conforto térmico para ovinos adultos, com exceção da umidade relativa do ar, que ficou com média diária de 67,5%. A temperatura retal dos animais esteve dentro da faixa normal, sendo o grupo genético Morada Nova o que apresentou menor valor (38,6 ºC). A frequência respiratória dos animais em cada grupo genético ficou acima do valor recomendado, porém o Morada Nova apresentou o menor valor (43,5 mov min -1 ); em contrapartida, o Cariri e o Barriga Negra apresentaram os maiores valores (48,0 e 47,3 mov min -1 , respectivamente). Os animais com pelagem mais escura e de maior porte, como os da raça Cariri, apresentaram maior gradiente térmico entre a temperatura do ar e a temperatura superficial. Os animais apresentaram alto índice de tolerância ao calor, ou seja, bem adaptados ao ambiente tropical, podendo o grupo genético Cariri ser caracterizado como o menos adaptado e o Morada Nova considerado o mais bem adaptado às condições experimentais. PALAVRAS-CHAVE:ambiência, conforto térmico, animais nativos.

This study was conducted to investigate the adaptive profile of the Garfagnina goat breed in two different seasons (spring and summer) through physiological, biochemical, haematological, and hormonal parameters. Fifty adult lactating females were studied twice a day (morning and afternoon) in each season. The air temperature, black globe temperature and air relative humidity was recorded using an automatic weather station. Physiological parameters recorded were rectal temperature, respiratory rate, heart rate, skin temperature and rectalskin temperature gradient. The results of this study showed that there was a significant effect of season and period on all environmental variables. Physiological variables, rectal temperature, respiratory rate, heart rate and skin temperature showed higher values in the afternoon in both seasons. Both biochemical and hormonal parameters were significantly affected by season of the year. Biochemical and hormonal characteristics undergo changes during different seasons such that metabolism is reduced during heat stress and accelerated during cold stress; these metabolic changes are controlled by the thyroid hormones and cortisol. It has been shown from this study that these hormones facilitates the physiological parameters involved with the adaptation process confirming that adaptive capacity of animals cannot be described solely by rectal temperature and respiratory rate.

The Garfagnina goat is an endangered native goat population from Italy. This study aims to give a contribution to the milk quality assessment of the native goat during the two productive seasons, spring and summer, and to verify the relationships between some meteorological data and physiological and milk quality parameters. Individual milk samples were taken in the two seasons. Physiological parameters and meteorological data were also registered. All the milk samples were measured for volume and analysed for: dry matter, total nitrogen, casein, ash, lactose, fat, milk fatty acid (FA) composition, number and diameter of the fat globules, and rheological parameters. There were not differences in the average diameter of the milk fat globules (2.27 ± 0.28 lm) and in milk gross composition between the two seasons, except for lactose which was significantly lower in summer. During summer a significant increase in some longchain FAs such as CLA c9,t11, C18:1 t11, C18:0, C18:3 n3, C20:0, C22:0, C22:2 was observed, whereas short-chain FAs (C6:0, C8:0, C10:0), which are responsible for the development of unpleasant aromas, as well as monounsaturated C16:1, C17:1 c9, C20:1, C22:1 and polyunsaturated FAs C20:2, C20:3 n3 decreased. The average PUFA n6/PUFA n3 ratio was 1.7 and the lowest values were recorded in summer. In summer a worsening of the clot, which was less firm, was found. Environmental parameters were found to be linked to the milk FAs, while heart rate and skin temperature were negatively linked to milk yield and lactose, respectively. ARTICLE HISTORY