الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 273 |  |  |
| | | from | 273 | | |
Abstract
The heat stress is considered the most potent environmental stressor for livestock in tropical and subtropical (e.g. Egypt) regions, which affects the animal health as well as the productive and reproductive performances. It may cause a tremendous worldwide economic loss in livestock and dairy animals in the future if the climate of the Earth continues to warm as most predict. In addition, the decrease in the animal splanchnic blood flow during the heat stress in order to dissipate the excess of heat through periphery (skin) may cause cellular hypoxia and excessive production of free radicals in the internal organs leading to an oxidative damage of such organs including intestine, and hence endotoxemia due to bacterial translocation from the intestinal lumen into the bloodstream through the damaged intestinal mucosa.
Recently, many reports suggested the beneficial effects of marine macroalgae, especially the edible brown seaweeds, on animal health. Red sea is rich in brown seaweeds especially genus Sargassum that contains a large amount of the phenolic compounds (the most effective antioxidants) and polysaccharides (which showed excellent anti-inflammatory activity). Among all the collected brown seaweeds (Cystosira myrica, Padina gymnospora, Sargassum aspirofolium, Sargassum latifolium, Sargassum muticum and Turbinaria sp.) from the Red Sea at Hurghada coast during the spring season, Sargassum latifolium was selected to achieve the aim of the present study, because it was the easiest species to harvest and the most abundant one. In addition, Sargassum latifolium had a considerable content of carbohydrates, proteins and minerals, and also was rich in the most active antioxidant and anti-inflammatory components such as alkaloids, flavonoids, carotenoids and vitamins.
The present study aimed to evaluate and compare the alleviative effects of two different doses (2% and 4% of the diet) of Sargassum latifolium (family: Sargassaceae) every 10 days for 40 consecutive days on some physiological and immunological alterations in Barki male sheep (Ovis aries) that were exposed to the environmental heat stress (temperature-humidity index, THI > 25.6) or were challenged twice with the commercially prepared bacterial endotoxins (Escherichia coli lipopolysaccharides, LPS, 1.25 μg/kg body weight, injected intravenously) on the 28th day and the 35th day of the experimental period. Furthermore, the study extended to detect any deleterious effects caused by consuming Sargassum latifolium on the animal health.
The results of the present study showed that the environmental heat stress increased significantly (P<0.01-0.001) the thermo-respiratory response (coat, skin and rectal temperatures and respiration rate) of the animals (especially at 2:00 pm) and induced normochromic normocytic anemia, which then developed to hypochromic normocytic anemia at the end of the experiment. Also, it induced hyperglycemia and dyslipidemia, as well as increased significantly (P<0.05-0.01) the risk of atherosclerosis. In addition, it altered significantly (P<0.01-0.001) the kidney functions and blood antioxidant defense system (catalase and superoxide dismutase activities and total antioxidant capacity), as well as increased significantly (P<0.05-0.001) the serum markers for tissue damage (malondialdehyde concentration and alanine aminotransferase and lactate dehydrogenase activities). Moreover, it induced blood leukocytosis (mainly due to lymphocytosis), and a significant increase (P<0.05-0.001) in the erythrocyte sedimentation rate (ESR) and the concentration of serum IgM and serum inflammatory markers: interleukin (IL)-6, tumor necrosis factor (TNF)- and heat shock protein-70 (HSP-70).
However, challenge animals with the LPS increased significantly (P<0.05-0.001) the thermo-respiratory response except the coat temperature, since this group of animals was lived in comfortable environmental conditions (THI < 22.2), and induced normochromic normocytic anemia and hypercholesterolemia after the second challenge on the 40th day. Also, it altered significantly (P<0.05-0.001) the blood antioxidant defense system (catalase and superoxide dismutase activities), increased significantly (P<0.001) the serum markers for tissue damage (malondialdehyde concentration and lactate dehydrogenase activity) and ESR, as well as induced blood leukocytosis (mainly due to lymphocytosis and monocytosis) after the 1st and 2nd challenge with the LPS. In addition, it induced a significant increase (P<0.001) in the concentration of serum IgM and serum inflammatory markers (IL-6, TNF- and HSP-70) after the second challenge on the 40th day.
On the other hand, the diet containing Sargassum latifolium (especially 4%) modulated significantly almost all changes shown in the heat-stressed (HS) and LPS-challenged Barki male sheep as follows: (1) It modulated significantly (P<0.05-0.001) the increase in the thermo-respiratory response (except the coat temperature in the HS sheep), as well as the resulted anemia, systemic inflammation, hyperglycemia, and dyslipidemia in both HS and LPS-challenged sheep. (2) It improved significantly (P<0.05-0.001) the body-weight gain and kidney functions (only in the HS sheep), as well as the antioxidant defense system, and protected the animals from the the risk of atherosclerosis, oxidative stress, and tissue damage in both HS and LPS-challenged sheep.
In conclusion, the results obtained in this study affirmed that feeding sheep with diet containing 2-4% Sargassum latifolium (collected from the Red Sea at Hurghada coast) was suitable for animal nutrition and did not induce any deleterious effects, as well as efficiently protected Barki male sheep from the harmful effects of the environmental heat stress and the challenge with the bacterial endotoxin through improving the animal antioxidant defense system and regulating the inflammatory responses.