Características termorreguladoras e desempenho de cabras leiteiras no terço inicial da lactação em clima tropical.

Resumo: Teve-se como objectivo avaliar o comportamento de caracteristicas termorreguladoras, a condicao corporal e a producao de leite no inicio da lactacao de 45 cabras de diferentes tipos raciais (15 da raca Saanen, 15 cruzadas Sem Padrao Racial Definido (SPRD) x Murciana e 15 Alpinas Americanas). Foram tomadas a temperatura retal, a frequencia respiratoria, o escore da condicao corporal a producao diaria de leite e as concentracoes plasmaticas de triiodotironina (T3) e tiroxina (T4) avaliados ate os 36 dias da lactacao. As concentracoes de T3 e T4 foram obtidas pelo metodo de radioimunoensaio. As variaveis meteorologicas foram registradas as 15 h, no mesmo horario da coleta dos dados fisiologicos. Os resultados obtidos indicaram que as cabras da raca Alpina Americana tiveram as maiores temperaturas retais e frequencias respiratorias, alem de menores concentracoes de triiodotironina e tiroxina, associados a menor producao de leite e condicao corporal possivelmente como reflexo de menor adaptacao ao clima. As cabras Saanen e _ Murciana SPRD apresentaram menores temperaturas retais e frequencias respiratorias, maior escore da condicao corporal e concentracoes sericas de triiodotironina e tiroxina. As temperaturas retais foram iguais entre os grupos geneticos _ SPRD x _ Murciana e diferente para as cabras saanen. No terco inicial de lactacao animais mesticos leiteiros juntamente com as cabras Saanen, demonstraram maior adaptabilidade, bom desenvolvimento corporal e melhor desempenho lactacional. As cabras Alpinas Americanas mostraram menores respostas adaptativas e produtivas o que evidencia a importância do ambiente termico na criacao desses animais. [Thermoregulatory traits and performance of dairy goats in early lactation in tropical weather]. Abstract: The objective of this study was to evaluate physiological and performance characteristics in early lactation of dairy goats of several breeds, namely thermoregulation, body condition and milk production. Forty five females were used (15 Saanen, 15 of crosses between undefined breed and _ Murciana and 15 American Alpine). Records were made of rectal temperature, respiratory rate, body condition score and daily milk production in the 36 first days of lactation. Plasma concentrations of triiodothyronine and thyroxine were obtained by radioimmunoassay method. The meteorological variables were registered at 15 pm, at the same time as the collection of physiological indicators. Results indicate that American Alpine goats had higher rectal temperatures and respiratory frequency, lower concentration of triiodothyronine and thyroxine, associated to a smaller milk production and body condition, possibly due to the worse climate adaptation. Saanen and _ Murciana crosses presented lower rectal temperatures and respiratory frequency, higher body score and triiodothyronine and thyroxine concentrations. Rectal temperatures were similar between the genetic groups undefined breed x _ Murciana and different for Saanen goats. In the initial third of lactation crossbred goats along with Saanen goats showed greater adaptability, good physical development and better milk production. The American Alpine goats showed less productive and adaptive responses which highlights the importance of the thermal environment in the management of these animals.