Effect of dietary replacement of soybean meal protein with cotton seed meal protein on biochemical and histological features of Nile tilapia muscle

الملخص EN

This experiment intended to assess the effect of cottonseed meal (CSM) as a partial and complete replacement of soybean meal on biochemical analysis, histological features, the carcass characteristics and meat quality traits of Nile tilapia (Oreochromis niloticus) after 22 weeks of feeding period.

Fish with an average initial body weight of 46.4±1.8 g were stocked in 15 glass aquarium (90 L each) of 20 fish each.

CSM was incorporated at levels of 0, 25, 50, 75, and 100% with soybean meal protein.

Diets were fed to fish twice daily at a rate of 3% of body weight during 22 weeks the experimental period.

The results of the present study revealed that groups of fish fed diet containing 50% CSM had significant highest final weight (189 g/fish), body weight gain percent (297.2%), carcass weight (96 g fish-1), fillet weight (49.0 g fish-1) and dressing % (50.5 %) compared with fish fed control and other diets.

The lowest values of final body weight, body weight gain percent, carcass weight, fillet weight and dressing % were significantly obtained with fish fed diet containing 100% CSM.

Biochemical analysis of muscles indicated that the maximum dry matter, crude protein crude lipid and ash contents were obtained with groups of fish fed on the diet containing 50% CSM, while the lowest values were obtained with groups of fish fed on the diet containing 100% CSM.

Fish fed control diet and 50% CSM diet had significantly the highest values of water holding capacity (W.H.C.), 7.41 and 7.18, respectively, compared with others.

The muscles showed histological alterations in fish included degeneration in muscle bundles accompanied with fat vacuole in muscle bundles.

Splitting of muscle fibers and atrophy of muscle bundles were seen with increasing CSM concentration more than 50%.

Therefore, these findings suggest that up to 50% of soybean meal protein can be replaced by cotton seed meal protein in Nile tilapia diets without any adverse effects on biochemical analysis, histological features, the carcass characteristics and meat quality traits of Nile tilapia