Hameeda Kalhoro

SUMMARY Nutraceuticals, including amino acids, carbohydrates, minerals and vitamins, have gained more attention, owing to multiple nutritional and health benefits, including maintaining the normal physiological status and disease prevention, thereby improving production performance of poultry birds. In commercial poultry production systems, chicks do not have access to feed and water for about 24–48 h during transportation between hatchery and production farm. This delay time poses negative effects on early feed intake, organ development, natural exposure to microbiota and immune sensitisation of chicks. Early feeding via in ovo inoculation of nutrients and feed additives to the developing embryo during 12th or 17th to 18th days of incubation significantly mitigates the adverse effects of starvation and enhances post-hatch performance and health of poultry birds during pre-andpost-hatch periods. The direct administration of various supplements, nutrients, drugs, vaccines, immunostimulants and biological substances through an in ovo route has diverse advantages including boosted health status, immunity and production performance of post-hatch poultry birds. Early feeding of nutrients during embryonic life has numerous benefits, such as improvements in weight gain, feed efficiency, growth rate and digestive organ development; decrease in morbidity and mortality of embryo; reduction in skeletal disorder; and boosted immunity, muscular development and meat yield of poultry birds. Furthermore, early in ovo feeding of nutraceuticals has provided better protection against a number of infectious pathogens than post-hatch supplementation. The current review aimed to provide a promising insight for the promotion of in ovo technology in order to supply different nutraceuticals (amino acid, vitamins, minerals and carbohydrates) directly into the developing embryo to achieve an improvement in post-hatch growth, immune responses and antioxidant defence along with the development of gastrointestinal tract. Additionally, this review highlights the future of in ovo technology as a strategy to improve the productive performance of poultry birds.

The present study aimed to investigate the macroscopic and histological structure of the gastrointestinal tract (GIT) of Larimichthyscrocea (Richardson, 1846). It consists of esophagus, stomach regions, pyloric caeca, intestinal regions, and rectum. Sixteen tubular light yellowish pyloric caeca of similar sizes were observed in all individuals. The digestive wall consists of mucosa, submucosa, muscularis, and adventitia. No major differences appeared in the structure of the tunica, epithelial cell types, connective tissues and musculature glands of L.crocea GIT. The mucosal epithelia in the oesophagus has longitudinal branched folds with frontward and hindmost zones. The gastric tunica mucosa has a characteristic folded structure and can be divided into three regions. The intestinal tunica mucosa is characterized by villi structures and numerous mucus-secreting cells. Mucus-secreting goblet cells were strongly positive to AB at pH 2.5 in the oesophagus (excluding gastro-oesophageal junction) and intestine mucosal regions, which indicates an abundance of carboxylate mucins. The surface epithelia of the gastric mucosa is PAS-positive and AB-negative. SEM examination revealed that cells in the epithelium of the esophagus have an unbroken apical layer and goblet cells. The intestinal coefficient (IC) of L.crocea was 0.80 ± 0.21, consistent with a carnivorous or omnivorous habit. Our study adds the knowledge of the digestive system of L.crocea and might be useful in the management of L.crocea stocks.

Acanthopagrus schlegelii is an autochthonous teleost species concerning the remarkable economic importance and prevalent fish cultivated in China as well as in different nations of South‐East Asia. Little is known about the digestive tract (DT) morphology of A. schlegelii. Therefore, anatomical and histomorphological aspects of A. schlegelii DT were examined by light and scanning electron microscope (SEM). Anatomically, DT of A. schlegelii was mainly formed of oesophagus, well‐developed stomach and fingers like pyloric caeca (four in number), intestinal regions and rectum. Histomorphologically, oesophagus occurred as a shorter tube‐like organ presenting a longitudinal folded mucosa that connects oropharynx cavity to stomach. Stomach was a muscular thick‐wall organ that included three regions, thickly longitudinal folds were observed in the first (cardiac) and last (pyloric) regions, whereas the second (fundic) region showed folds in different directions. Long villi were observed within pyloric caeca and anterior intestine. Tunica muscularis appeared narrow in the anterior intestine, whereas thicker in the posterior part of the intestine. Collectively, anatomical and histomorphological aspects of A. schlegelii DT are consistent with the carnivorous habit of this species. These data could be a potential source to modify better methods of nutrition and identify the DT pathogenic conditions in farming of this fish.