Effect of temperature humidity index on the onset of post- partum ovarian activity and reproductive behavior in Bos indicus cows

Abstract

The effect of climatic factors on ovarian activity and reproductive behavior (RB) was evaluated in 46 Bos indicus cows kept under grazing conditions. Temperature-humidity index (THI) was used as an indicator of stress and divided in alert, damage and emergency levels. Fat thickness (FAT) was taken during the last trimester of gestation (LTG) to approximately 90d postpartum (PP). At 30d PP animals received a progesterone (P4)-releasing device (CIDR) which was withdrawn 9d later. Ovarian activity was assessed by blood progesterone on days 21, 24, 27, 30, 49, 51, and 54 PP. Animals were divided into three groups, higher, and moderate RB and non-behavior. Sixty percent presented a THI >74 increasing dramatically from June to September up to >78. During LTG, animals lost 27% of their body reserves contrasting to PP where an increase of 2.6% (P=0.002) was observed. The percentages of cyclic and non-cyclic animals were 57 and 43%, respectively (P> 0.05). Seventy-two percent displayed RB and 28% were non-behavior (P<0.05). A negative correlation (r =-0.307; P = 0.038) between THI and RB, and a positive correlation (r = 0.427; P = 0.003) between the onset of ovarian activity and RB were observed. Differences in THI during the LTG (P<0.01) were observed between cyclic and non-cyclic animals. Non-behavior cows in the LTG had a higher THI (P <0.05). High levels of THI have a negative effect on the resumption of ovarian activity and RB in Bos indicus especially if high THI occurs during the last trimester of gestation.

Bioclimatic zoning for dairy cows in Brazil by statistical modeling

“…4(c)). Mato Grosso showed a mean similar to that of Mato Grosso do Sul during the winter, with a value of 19.86 ± 0.90 °C 29 …”

“…26,27 Several indices have been used to evaluate the level of cattle stress caused by climate conditions but the Temperature and Humidity Index (THI) is used the most. [28][29][30][31][32][33] The THI provides a single value that shows the influence of air temperature and relative humidity on animal performance. 11,34,35 This index is used as a tool to identify the timing and intensity of the effects of climate conditions.…”

Factores que afectan la tasa de preñez mediante transferencias de embriones por fertilización in vitro en novillas multirraciales en condiciones de trópico colombiano

“…Cordeiro et al (19) en su estudio demostraron que el estrés por calor afecta negativamente las tasas de concepción de vacas cruzadas (Bos taurus × Bos indicus) transferidas al norte de Brasil, donde tuvieron una disminución en las tasas de concepción cuando ITH alcanzó 75.7; en contraste, el mes que obtuvo la tasa de concepción más alta presentó el clima más favorable durante el experimento (ITH 73.1). Se ha mencionado (20) que los niveles altos de THI tienen un efecto negativo sobre la reanudación de la actividad ovárica y el comportamiento reproductivo en vacas Bos indicus mantenidas en pastoreo, especialmente si se produce un THI alto durante el último trimestre de gestación.…”

Factors affecting the in vitro embryo production in buffalo (Bubalus bubalis): A review

“…These results might be due to the increased daylight length with higher environmental temperature leading to hyperprolactinemia, the decreased secretion of gonadotropins and steroids. These factors affect the folliculogenesis, oocyte quality and embryonic development (Diaz et al 2020). The degeneration rate of the cumulus cells and ooplasm are also higher in the hot than in the cold season without affecting the expansion of the cumulus cells during in vitro maturation.…”