Respostas fisiológicas, hematológicas e produtivas de diferentes genótipos ovinos em função do ambiente e da dieta.

Abstract

The aim was to evaluate and compare the physiological, hematological and performance variables of three genetic groups of sheep: Morada Nova, Somalis and crossbreed Dorper x Somalis in the Brazilian semiarid region submitted to diets with and without inclusion of jitirana. The research was carried out at Sheep sector of Research Center for the development of semi-arid, in the Center for Health and Rural Technology, Federal University of Campina Grande, Campus of Patos- PB. Thirty male uncastrated animals with approximately 150 days of age and mean initial live weight of 22.5 ± 2 kg, 10 of each genotype were used, a half of which had 30% of the tifton hay replaced by jitirana hay. The temperature and relative humidity of the air were calculated, calculated the ITGU and measured the rectal temperature (RT), respiratory rate (RR) and heart rate (HR) and surface temperature (ST) in the morning and afternoon shifts. Four blood samples were collected in all animals to evaluate the hematological profile. Were analyzed daily dry matter intake (DMI), total weight gain (TWG), daily average weight gain (DAWG), feed conversion (FC), feed efficiency (FE) and daily water consumption (DWC). The design was completely randomized (DCR), and the factorial scheme 3x2x2, being three genotypes and two diets and two shifts, with five replicates each. The values for ITGU were 81 in the shade and 90 in the sun and there was a significant difference for the studied variables in relation to the shifts, being higher in the afternoon. The mean ST of the sheep was 35.48 in the morning and 38.11 in the afternoon, and Morada Nova presented lower RT among the genetic groups, demonstrating greater heat tolerance. Morada Nova sheep presented lower numbers of red blood cells, leukocytes and lymphocytes and higher values for mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and platelet anisocyte index (PAI). The inclusion of jitirana hay did not promote changes in any haematological or performance variables analyzed. There was a genotypic difference for all the performance variables evaluated and the crossbreed animals presented the highest mean values for DMI, TWG, DAWG, FC and DWC. The genetic groups studied were adapted and tolerant to the climatic conditions of the Brazilian semi-arid region. The substitution of 30% of tifton hay by Jitirana hay did not negatively affect the thermoregulatory capacity and did not influence the hematological profile and could be included in the sheep diet. Thermal stress can influence the values of the hemogram of ovine by modifying the concentration of some constituents of the blood. Different ovine races can present different values in the hemogram according to the adaptability to the environment in which they live and due to inherent characteristics of each breed. The Dorper x Somalis crossbred sheep are recommended for intensive husbandry in the northeastern semiarid conditions due to their rusticity and good productive indexes. Further studies should be developed to establish hematological reference values for the different sheep races and to evaluate higher percentages of inclusion of Jitirana hay in the sheep diet.