OBJECTIVE The objective of this experiment was to investigate the effects of heat stress on milk protein and blood amino acid profile in dairy cows. METHODS Twelve dairy cows with the similar parity, days in milk and milk yield were randomly divided into two groups with six cows raised in summer and others in autumn, respectively. Constant managerial conditions and diets were maintained durin...

The influence of temperature on the hemodynamic adjustments to direct passive heat stress within the leg's major arterial and venous vessels and compartments remains unclear. Fifteen healthy young males were tested during exposure to either passive whole body heat stress to levels approaching thermal tolerance [core temperature (Tc) + 2°C; study 1; n = 8] or single leg heat stress (Tc + 0°C; st...

An original method to induce heat stress was used to clarify the time course of changes in heat shock proteins (HSPs) in rat skeletal muscles during recovery after a single bout of heat stress. One hindlimb was inserted into a stainless steel can and directly heated by raising the air temperature inside the can via a flexible heater twisted around the steel can. Muscle temperature was increased...

Calcium (Ca+) may be involved in plant tolerance to heat stress by regulating antioxidant metabolism or/and water relations. This study was designed to examine whether external Ca2+ treatment would improve heat tolerance in two C3, cool-season grass species, tall fescue (Festuca arundinacea L.) and Kentucky bluegrass (Poa pratensis L.), and to determine the physiological mechanisms of Ca2+ effe...

Cells apoptosis induced by intense heat stress is the prominent feature of heat-related illness. However, little is known about the biological effects of heat stress on cells apoptosis. Herein, we presented evidence that intense heat stress could induce early apoptosis of HUVEC cells through activating mitochondrial pathway with changes in mitochondrial membrane potential(ΔΨm), release of cytoc...

The Nature of the Problem Heat stress has two major actions on physiology of the female that reduce the probability of a cow becoming pregnant. First, heat stress reduces ability to detect estrus. On one dairy in Florida, only about 18-24% of estruses in hot months were detected by herdsmen while 45-56% of estrus periods were detected in cool months (Thatcher and Collier, 1986). The reduction i...

Sertoli cells are an essential group of cells in seminiferous epithelium which provide nutritional and structural supports for spermatogenic cells via cell junctions. In this study, the gene expression of connexin-43, the most abundantly distributed gap junction protein of cells, was investigated in ram Sertoli cells under mild and severe heat stresses with real-time quantitative PCR. Sertoli c...

BACKGROUND: The effect of heat stress on physiologicalparameters has been well documented. However, there arereports of a genetic based heat tolerance in some sheep breeds.OBJECTIVES: The aim of the present study was to monitor thephysiological responses of an Iranian fat-tailed breed againstheat stress and an acute stress insult. METHODS:Atotal numberof 15 fall-born ram lambs were selected and...

Heat stress contributes to higher morbidity and mortality in humans and animals and is an agricultural economic challenge because it reduces livestock productivity. Redox balance and associated mitochondrial responses appear to play a central role in heat stress-induced skeletal muscle pathology. We have previously reported increased oxidative stress and mitochondrial content in oxidative muscl...

BACKGROUND AND AIMS Exposure to higher-than-optimal temperatures reduces crop yield and quality, mainly due to sensitivity of developing pollen grains. The mechanisms maintaining high pollen quality under heat-stress conditions are poorly understood. Our recently published data indicate high heat-stress-induced expression of ethylene-responsive genes in tomato pollen, indicating ethylene involv...