SummaryElevated ambient temperatures affect animal production and welfare. Animal's reduced production performances during heat stress were traditionally thought to result from the decreased feed intake. However, it has recently been shown that heat stress disturbs the steady state concentrations of free radicals, resulting in both cellular and mitochondrial oxidative damage. Indeed, heat stress reorganizes the use of the body resources including fat, protein and energy. Heat stress reduces the metabolic rates and alters post-absorptive metabolism, regardless of the decreased feed intake. Consequently, growth, production, reproduction and health are not priorities any more in the metabolism of heat-stressed animals. The drastic effects of heat stress depend on its duration and severity. This review clearly describes about biochemical, cellular and metabolic changes that occur during thermal stress in farm animals.
In recent years there has been enormous interest in researching oxidative stress. Reactive oxygen species (ROS) are derived from the metabolism of oxygen as by-products of cell respiration, and are continuously produced in all aerobic organisms. Oxidative stress occurs as a consequence of an imbalance between ROS production and the available antioxidant defence against them. Nowadays, a variety of diseases and degenerative processes such as cancer, Alzheimer's and autoimmune diseases are mediated by oxidative stress. Heat stress was suggested to be an environmental factor responsible for stimulating ROS production because of similarities in responses observed following heat stress compared with that occurring following exposure to oxidative stress. This manuscript describes the main mitochondrial sources of ROS and the antioxidant defences involved to prevent oxidative damage in all the mitochondrial compartments. It also deals with discussions concerning the cytotoxic effect of heat stress, mitochondrial heat-induced alterations, as well as heat shock protein (HSP) expression as a defence mechanism.
are vacuolar pigments composed of a nitrogenous core structure, betalamic
acid. Betalamic acid condenses with imino compounds (cyclo-DOPA/its glucosyl derivates) or amino acids/derivates to form violet
betacyanins and yellow betaxanthins. These pigments have gained the
curiosity of scientific researchers in recent decades. Their importance
was increased not only by market orientation toward natural colorants
and antioxidants but also by their safety and health promoting properties.
To date, about 78 betalains have been identified from plants of about
17 families. In this review, all of the identified pigments are presented,
followed by a comprehensive discussion of their structure–activity
Upper limit of thermal stability and subsequent rise of thermoregulatory functions are affected by body temperature. This study was designed to determine the effects of rectal temperature (RT) on dairy cows' performance (heart rates (HR), respiratory rates (RR), milk yield (MY), dry matter intake (DMI), digestibility, plasma concentration of vitamin C under hot climate. This study was carried out in 2009, in northwest of Tunisia using 30 Holstein cows in mid lactation. The experiment was performed in spring (15th of February-15th of March: P1) and summer (1st-30th of August: P2). On each test day, temperature-humidity index (THI), RT, HR, RR, MY, DMI, digestibility and plasma VC concentration were determined. All this parameters were affected (P < 0.001) when the THI increased from 65.62 (P1) to 83.27 (P2). Regression analyses were carried out between THI index and some parameters (HR, RR, MY, DMI, digestibility, plasma concentration of vitamin C) and between RT and same parameters (HR, RR, MY, DMI, digestibility, plasma concentration of vitamin C). Characteristics of regression analyses in the two modes were different as also were R2 and r (correlation coefficient) of the regressions. R 2 in regressions on RT (R 2 (RT, DMI) = 0.92 (P < 0.01); R 2 (RT, MY) = 0.91 (P < 0.001)) was markedly higher relative to R 2 in regressions on THI (R 2 (THI, DMI) = 0.76 (P < 0.001); R 2 (THI, MY) = 0.63 (P < 0.001)). The two regressions modes suggest that increasing R 2 in regressions on RT confirms that rectal temperature constitutes a larger component of total variance of responses in dairy cows to hot environmental temperature.
Egg storage duration and breeder age are probably interacting to influence egg quality, hatchability, and hatchling quality. To evaluate this interaction, the impact of breeder age (31, 42, 66 weeks) and storage duration (2, 5, 12, 19 days) was investigated on broiler breeder eggs (Arbor Acres). Thick albumen diameter and pH increased, and yolk dry matter decreased between 2 and 19 days of storage. With the increase of breeder age from 31 to 66 weeks, albumen height, percentage and dry matter and shell percentage decreased and the egg weight and yolk percentage, dry matter and diameter increased. Prolonged egg storage increased the yolk pH in all breeder ages, but earlier and steeper in the oldest breeders. Prolonged egg storage resulted in a lower hatchability of set and fertile eggs due to a higher percentage of embryonic mortality. Early mortality increased earlier and steeper with prolonged egg storage in the oldest compared to younger breeders. Between 5 and 19 days of storage, yolk free body mass, liver and proventriculus + gizzard percentages decreased, as well as hatchling length and yolk efficiency (yolk absorption per initial yolk weight). The latter effects were most pronounced in the younger than in the older breeders. Therefore, eggs are preferably stored shorter than 7 d, but if long storage (≥12 days) cannot be avoided, we recommend to store eggs of older breeders when egg quality and hatchability are most important. In case hatchling quality is most important, it would be better to store eggs of younger breeders (31 weeks) for a prolonged period.
Cacti are known for their minimum water requirement. They grow extensively in arid lands, where they were traditionally used for both human and animal food. Opuntia ficus-indica, commonly referred to as prickly pear or nopal cactus, was known as a medicinal plant, owing to its rich composition in polyphenols, vitamins, polyunsaturated fatty acids and amino acids. This makes cactus pear a promising crop for commercial food applications. Recent scientific investigations showed thatcactus products may be efficiently used as a source of foods additives, mainly fibre, colorants and antioxidants. Tablets, cookies and other forms of fibre derived from cactus cladodes are currently marketed in severalAmerican countries. This review details the main functional phytochemicals characterizing different tissues of Opuntia ficus-indica.
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