Adaptive dynamics of dairy goats in a temperate region.

Abstract

Physiological and hematological traits and productive performance of Spanish Majorera and Palmera goats reared on the Island of Tenerife-Spain were assessed. 50 adult, clinically healthy, multiparous female goats were studied for 18 months. The data were analyzed in a two (breeds) x four (season) factorial scheme. Multivariate analysis and machine learning were used to assess the relationship between adaptive responses and climatic variables. There was no interaction effect between season of the year and breed for physiological responses (P > 0.05), except for coat surface temperature (P < 0.001). Respiratory rate and rectal temperature had no effect on breed c unlike heart rate and coat surface temperature. All thermoregulatory variables showed variations between seasons. The goats had a higher respiratory rate (P < 0.001) in summer and autumn. Rectal temperature was higher in spring (P < 0.001), but similar to winter (P > 0.05), whereas the heart rate was higher by 16.67% in winter when compared to other seasons (P < 0.001). The surface temperature of the coat presented higher values for the Majorera breed when compared to the Palmera in summer and spring. The Majorera breed showed greater productive performance (body weight; P < 0.05). In winter, the red blood series of Majorera goats showed higher values for hematocrit, hemoglobin, mean corpuscular volume and mean corpuscular hemoglobin (P < 0.05). The white blood series is similar between breeds (P > 0.05). There is a dynamic in the adaptive mechanisms used by Majorera and Palmera goats during the seasons. The temperate climate on Tenerife Island has a greater impact on Majorera goats (r² canonical = 0.76; P < 0.001) when compared to Palmera goats (P = 0.68; P < 0.001). The surface temperature of the coat is the first activated thermoregulatory mechanism for both breeds (P < 0.001). However, only Majorera goats presented secondary mechanisms which are related to heart rate for lower coat surface temperature values, possibly due to vasoconstriction in winter; and for higher values of rectal temperature when the surface temperature of the coat increases in summer. It is concluded that both breeds are adapted to the temperate climatic conditions of the Island of Tenerife, but there is a seasonal adaptive dynamic. Majorera breed animals have greater body weight, but are less tolerant to the Island's climate. In the warmer seasons, these animals increase the surface temperature of the coat to dissipate endogenous heat and in the colder seasons they increase the number of red cells, which demonstrates their adaptability to the winter climate on the Island of Tenerife.