ObjectiveThis study was conducted to investigate the effects of probiotic, prebiotic and synbiotic with and without feed restriction on broilers performance, blood parameters, carcass characteristics, and feed cost of production from 1 to 56 days of age.MethodsTwo hundred and forty unsexed one day-old chicks of Arbor Acres breed were used. Two trials, I and II, were conducted, with 120 birds in both. Each trial was divided into 4 equal groups. The birds in trial I were fed ad libitum throughout the experiment, while the chicks in trial II were fed ad libitum during the first week of age, then subjected to 5 hours/d of feed restriction from the beginning of the second week up to the end of the experiment. In both trials, the birds in group 1 were fed on a control diet while the other groups were given the same control diet supplemented either with a probiotic in group 2, prebiotic in group 3, or synbiotic in group 4.ResultsIt was found that chicks fed diets supplemented with probiotic, prebiotic and synbiotic (with and without feed restriction) exhibited higher body weight and feed efficiency than chicks fed the control diets. The feed additives in both trials did not affect hemoglobin, serum total protein, albumin, globulin, glucose, and total cholesterol, except the packed cell volume which was increased in the additive treatments with restriction at the end of the experiment. Moreover, the dietary treatments did not influence the carcass yield. However, the relative weights of liver, gizzard and proventriculus, small intestine and bursa of fabricius were found to be increased. The additives decreased the visible fat in the carcass, with more decreasing effect in the additive groups with restriction. The lowest feed cost per kg of weight gain was observed in the birds fed diets supplemented with synbiotic, probiotic and prebiotic. Feed restriction improved the feed conversion ratio, economic return, but decreased the feed intake, serum total cholesterol and visible fat in comparison with non-restricted groups.ConclusionThe biological feed additives could be routinely added to broiler diets, especially when a feed restriction program is followed. Finally, it can be recommended to restrict feed, and add probiotic or synbiotic to increase weight, improve feed conversion rate and reduce feed cost of production.

This study was conducted to investigate the effects of including potato peels (PP) and sugar beet pulp (SBP), as unconventional feeds, with and without enzyme in broiler diets from 1 to 42 days of age by observing the growth performance, blood parameters and carcass characteristics. A total of 150, 1-day old, chicks were randomly assigned into five groups, each with 30 chicks. Birds in group 1 were fed on the control diet. Chicks in groups 2 and 3 were offered diets containing PP and SBP at the rate of 15% and 7.5%, respectively, while those in groups 4 and 5 were fed the same diets but with adding an enzyme mixture. Using the unconventional feeds in the diets was found to decrease the body weight (BW). However, the feed intake, weight gain and feed conversion did not differ from the control in PP at the grower period, but decreased in SBP throughout the experiment. Addition of enzyme greatly improved the BW in PP and SBP to a degree that it surpasses the control and also increased the feed intake and conversion. The total cholesterol and low-density lipoprotein cholesterol serum levels were decreased in all tested groups. Carcass yield was not affected by treatments, but the carcass fat content was reduced using the unconventional feeds with or without enzyme. In conclusion, PP can be used at a rate of 15% in the grower diets of broilers. Furthermore, 15% PP or 7.5% SBP can be included in starter and grower diets, but with the addition of enzymes. This can help in solving the problem of current shortage and rising costs of conventional feeds.

This study was conducted to evaluate the effect of using protease in diets of Nile tilapia on growth performance, water quality, blood parameters and intestinal morphology. The cost of these diets and their return on fish performance was calculated. A total of 360 fish were randomly allocated into four groups with triplicates (30 fish per replicate). Four diets were formulated; two controls (without protease supplementation) and two experimental diets (supplemented with protease). The first control diet contained the normal protein requirement (30% CP; control +ve), while the second control had a low protein content (29% CP; control −ve). The third diet was supplemented with protease at a dose of 500 g/ton, and its CP content was reduced to 29.0%, by reducing the fish meal content. The fourth diet contained the same CP level as the first control (30%) and supplemented with 250 g protease per ton feed. The experiment lasted for 14 weeks. The results showed that body weight and length, weight gain, specific growth rate, feed intake and feed conversion efficiency in the control −ve group (low CP) supplemented with protease were similar (p > 0.05) to that of the control +ve with normal CP content. However, these performance parameters were lower (p < 0.05) in fish fed low CP diet without protease supplementation. Providing protease to the control +ve diet improved all measured performance indices. The ammonia and nitrite concentrations of the water were reduced (p < 0.05) in control −ve and protease‐supplemented groups. The height and width of intestinal villi were increased (p < 0.05) in fish fed diets containing protease. The inclusion of protease reduced the diet cost and also the feed cost of fish weight gain. In conclusion, supplementation of protease can improve the productive performance of fish, spare dietary protein and produce economical diets. Moreover, it can help in improving the water quality of fish via lowering the ammonia and nitrite contents, or through increasing the degradation of dietary protein.

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This study was conducted to evaluate the effects of Spirulina platensis in Nile tilapia diets on growth performance, blood hematological and biochemical parameters, immunological status, and intestinal histomorphometry. A total of 228 fish were randomly allocated into four groups with triplicates (19 fish per replicate). The first group was fed the control diet, which contained no Spirulina supplementation. The other three groups were fed diets containing graded levels of powdered Spirulina: 2.5%, 5.0%, and 10.0% in the second, third, and fourth group, respectively. S. platensis was added to the diets partially substituting the fish meal content. The experiment lasted for 8 weeks. The results showed that dietary Spirulina supplementation improved (P < 0.05) the body weight and length, weight gain, specific growth rate, condition factor, and feed conversion efficiency. Moreover, Spirulina increased significantly (P < 0.05) the hemoglobin, PCV, RBCs, and WBCs count. Also, it increased the lymphocytes, eosinophils, IgM level, lysozyme activity, and phagocytic activity in the blood. Additionally, the Spirulina raised (P < 0.05) the serum albumin level but reduced (P < 0.05) the creatinine and urea levels. The addition of Spirulina increased (P < 0.05) the height and width of intestinal villi and the lymphocytes and goblet cells count in the intestine. The obtained results were increased by increasing the inclusion level of Spirulina, especially for body weight and length, weight gain, FCR, phagocytic activity, and intestinal parameters. In conclusion, supplementing S. platensis can improve the growth performance of fish. Moreover, it can stimulate the immunity of fish through increasing the level of immunological blood indicators (IgM, lysozyme, phagocytic activity, lymphocytes, and eosinophils) as well as the local intestinal immunity (lymphocytes and goblet cells). So, it can be recommended to use S. platensis in fish diets not only to improve the growth performance but also to enhance the immune status.