Estresse calórico sobre a luteólise de vacas holandesas não lactantes

• Ano de defesa: 2015
• Autor(a) principal: Mogollón García, Henry David [UNESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: Luteólise; Corpo lúteo; Prostaglandinas; Progesterona; Vaca
• Link de acesso: http://hdl.handle.net/11449/131984

The objective was to study the main genes associated with the production, maintenance and regression of the corpus luteum (CL) and correlate the findings with the production of progesterone in non-lactating Holstein cows, besides clarifying physiological mechanisms involved in the response to heat stress. The cows were synchronized with CIDR-SYNCH protocol and randomly distributed in two environments: thermoneutral (n = 12), temperature 24 ° C, humidity 50%; heat stress (n = 12), temperature 38 ° C, humidity 70%. The D0 was defined as the day of the second application of GnRH. In each environment three different treatments were performed and in D7, for each treatment 4 cows were used. Treatment 1: 2 ml saline; Treatment 2: 25 mg Lutalyse®; and Treatment 3: 12.5 mg Lutalyse®. The degree of heat stress was determined by the temperature and humidity index. Blood samples were obtained for determining plasma concentrations of progesterone (P4) by chemiluminescence immediately before and every 6 hours after treatment with PGF2α, until 24 hours. Subsequently, the collection was performed every 12 hours up to 48 hours. The respiratory rate, heart rate and rectal temperature were measured every 12 hours for 7 days; vaginal temperature was determined over 7 days with readings every 10 minutes. The respiratory rate, rectal and vaginal temperature were higher in heat stress environment when compared to thermoneutral (P <0.05). Heart rate did not differ between the two environments (P> 0.05). There was no difference (P> 0.05) in the concentration of P4 when the environments and their respective treatments were compared. However, when evaluating individually the environments, it was observed that the cows who received the treatment with ½XPGF2α in heat stress and thermoneutral environment showed an initial P4 decrease up to 18 hours with subsequent recovery, showing a partial luteolysis. This fact demonstrates that heat stress caused no ...