Effect of using a mixture of Caspian Sea water and drinking water on meat quality, intestinal morphology, and histopathology of liver and kidney tissues of broiler chickens

Introduction: Studies show that sodium chloride soluble in water can be used as a source of mineral supplementation to meet part of the mineral needs of birds and that sodium water can replace the dietary sodium supplement completely. Therefore, if it is possible to exploit this ability of poultry and to provide some of the water they consume from salt water, while preserving the country's fresh water resources, the problems caused by saltwater use will be largely resolved. This study examined the effect of high salt concentration in Caspian Sea water on the quality of the meat, intestinal morphology, and histopathology of the liver and kidney tissues of broiler chickens. As the permitted limit for total dissolved solids in broilers is 1000-3000 ppm, the amount of seawater used for broiler chickens was within this range.
Materials and methods: Based on the hardness of drinking water in poultry farms at 340 ppm and the annual mean hardness of seawater at 3,700 ppm, as well as the permissible NRC hardness limit for water consumption, the study was carried out in a completely randomized design with four experimental treatments including 1. Control, 2. A mixture of seawater and drinking water with TDS equal to 1000 ppm, 3. A mixture of seawater and drinking water with TDS equal to 2000 ppm, and 4. A mixture of seawater and drinking water with TDS equal to 3000 ppm in five replications. To check the quality of the meat at the end of the incubation period, five chickens of average weight were selected and slaughtered from each of the experimental groups. To measure the meat pH, we mixed 10 grams of minced chicken meat with 90 mL of distilled water and measured the meat pH with a calibrated pH meter. For the measurement of water retention, after centrifugation and weighing, the sample was placed at 70^°C for 24 hours, and its weight was again recorded and finally calculated by the formula. To check the textural characteristics of meat, cube-shaped samples (2×2×2 cm) and rectangular cubes (4×2×2 cm) at a speed of 1 mm/s with a pressure of 50% and a penetration depth of 10 mm were prepared. They have been tested with the Texture Profile Analyzer (TPA). For the histopathological examination of the liver and kidneys, which included sampling, fixing, and molding of samples, tissue cutting, staining, and laminating of samples, the birds were completely dissected at the end of the incubation period, and after the birds had been killed and their histopathological changes recorded on slides for microscopic examination. To examine the intestinal morphology, a 3 cm long sample from the mid-joint of the small intestine was prepared and transferred to a 10% buffered formalin stability solution after washing with 0.9% saline. All the same procedures were then applied to liver and kidney tissue samples, and finally, 6-mm diameter cross-sections were prepared and stained with hematoxylin and eosin staining to investigate intestinal morphology. The length, width, depth, and the ratio of the length of the villus to the depth of the crypt of each tissue sample were then measured under a microscope and used for the study.
Results and discussion: There is no significant difference in the feed conversion rate of treatments by adding different percentages of seawater to drinking water, but water consumption and moisture content of the litter have increased. Comparing the average parameters of meat under the different TDS caused by the mixture of Caspian Sea and drinking water, no significant differences were observed in the pH, gumness, coagulation, chewing time, and chewing consistency of the examined treatments. It has shown that different TDS of water have no effect on these meat parameters and statistically they have almost the same average. The only significant difference observed was between the flexibility, water retention capacity, and hardness of the meat tissue, which indicates that meat tissue from treatment with a high TDS had a lower water retention capacity than control treatment. Concerning the length of the villus, which is one of the morphological parameters of the small intestine, it may be considered to be related to the increased capacity of the bird to absorb nutrients, as the length of the villus increases. Slow, longer villi prevent faster passage and increase conversion factor, and lower crypt depths indicate a decrease in the metabolic regeneration of the intestinal epithelium. Based on the results for the length of the blisters, the largest difference compared to the control treatment was related to the treatment with 75% Caspian Sea water, which resulted in a statistically significant difference. Based on the results concerning the width (depth) of the villa and the depth of the tomb, no significant difference was observed when using a mixture of water from the Caspian Sea and drinking water. Results from histopathological examination of the kidney and liver tissues of the treatment groups in this study showed that consumption of 1000 ppm seawater in these animals did not result in significant changes in liver and kidney tissue. There was significant tissue damage in these liver and kidney tissues, and the severity of these changes and damage was directly correlated to the increased seawater concentration in the diet.
Conclusions: Based on the results of histopathological examination of kidney and liver tissues from the treatment animals, consumption of 1000 ppm seawater in these animals did not result in significant changes in liver and kidney tissue. When 50% of the water from the Caspian Sea was used and added to drinking water, no significant differences were observed in the ability to absorb and access nutrients from the intestinal villi and finally in the morphology of the small intestine.