Full text
| |
| Author(s): |
Cláudia Caroline Barbosa Amadeu
Total Authors: 1
|
| Document type: | Master's Dissertation |
| Press: | Pirassununga. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Zootecnica e Engenharia de Alimentos (FZE/BT) |
| Defense date: | 2012-02-28 |
| Examining board members: |
Evaldo Antônio Lencioni Titto;
Marcos Chiquitelli Neto;
Luciandra Macedo de Toledo
|
| Advisor: | Evaldo Antônio Lencioni Titto |
| Abstract | |
The aim of this study was to evaluate the heat tolerance of three meat sheep breeds, Santa Ines, Dorper and White Merino using Thermolysis capacity test. 97 non pregnant females (3 years old) were used in the study that took place in the summer. Physiological variables as rectal temperature (RT), surface temperature (ST), respiratory rate (RR) were measured after two hours under the shade (1), after one hour under the sun (2), fifteen (3) and thirty (4) minutes after sun exposure, and sweating rate (SR) on time 2. Were also collected behavioral data during three days in the period from 11:00 to 14:00 hours: say in the sun, standing posture, eating, ruminating and idling. RT1 means were equal Santa Ines and Dorper, and greater for White Merino (P<0.05). White Merino also had greater values for RT2, RT3 e RT4, followed by Santa Ines and Dorper (P<0.05). These results reflected the thermolysis capacity, being lower for Santa Ines breed (P<0.05). After sun exposure differences between ST were observed, and greater values were found for White Merino, followed by Dorper and Santa Ines breeds (P<0.05). In the same way, White Merino had the highest RR, followed by Dorper, which had higher RR compared to Santa Ines (P<0.05). All animals exposed to the sun for an hour showed increased RT, ST, RR values (P<0.05), and approached the levels found before exposure to the sun after thirty minutes of rest in the shade (Santa Ines and Dorper P<0.05; White Merino P>0.05). Sweating rate for Santa Ines breed was higher than those found for Dorper breed (P<0.05). There were differences among animals within each race (P<0.05), confirming the hypothesis of great variability among individuals and differences between the breeds. With respect to behavior, Santa Ines ewe grazed even during the hottest hours of the day, and a positive correlation of 0.64 between the individual thermolysis capacity and grazing in the sun was found, while the Dorper ewes remained preferentially under the shade due to the semi-confined management. In the present study, feedin management influenced the time under the shade. Under experimental climatic conditions, the studied ewes had theirs physiological parameters increased due to sun exposure, and Dorper and White Merino breeds showed a greater thermolisys capacity than the animals of the Santa Ines breed, which is a factor that can influence individual heat tolerance. (AU) | |
| FAPESP's process: | 09/04712-0 - HEAT TOLERANCE OF SANTA INES, DORPER AND MERINO OVINE BREDS |
| Grantee: | Cláudia Caroline Barbosa Amadeu |
| Support Opportunities: | Scholarships in Brazil - Master |