To evaluate the effect of decreasing dietary protein on growth performance, carcass traits, and intestinal mucosal morphometry, 180 female Hubbard strain broiler chickens were divided into 3 groups and fed 3 isoenergetic diets ad libitum from 14 d of age until slaughter age (49 d). The treatments varied according to 3 protein levels: high-protein diet (HiP, 22.5% CP, DM basis), medium-protein diet (MedP, 20.5% CP), and low-protein diet (LowP, 18.5%). Diets were obtained by replacing wheat middlings with soybean meal and were formulated to meet or exceed broiler amino acid requirements of the NRC. Morphometric indices of duodenum, jejunum, and ileum were measured at the end of the feeding period and included villus height, crypt depth, villus-to-crypt ratio, and apparent villus surface area. The dietary protein level had a significant effect on final BW of birds, whereas ADG, ADFI, and feed efficiency remained unaffected by dietary treatment. The muscle (breast and drumstick) yields were significantly higher in birds fed the HiP diet compared with those of the MedP and LowP diets. Meat quality traits were not affected by the protein level. The villus surface area of all intestinal segments did not change among groups. Instead, reducing the dietary protein level to 20.5% resulted in a higher villus height and villus height to crypt depth ratio in the duodenum and ileum. On the basis of our findings, even if the high-protein diet promoted meat yield, a medium-protein diet could positively support broiler growth performance, as confirmed by favorable morphometric features of the intestine.

Melanomacrophage centres (MMCs), located in different organs of non-mammalian vertebrates, play a role in the destruction, detoxification or recycling of endogenous and exogenous materials. Cytochrome P450 monoxygenase 1A (CYP1A) is involved in xenobiotics biotransformation, and its liver expression is considered as a biomarker for detecting exposure to environmental pollutants. Atlantic bluefin tuna (ABFT), Thunnus thynnus L., liver samples were collected from: wild animals caught in the eastern Atlantic; juveniles reared in the central Adriatic; juveniles reared in the northern Adriatic; adults reared in the western Mediterranean. The samples were processed for basic histology, histochemistry and for CYP1A immunodetection. An unexpected high density of MMCs, containing ferric iron and lipofuscin-ceroids, was detected in the juveniles sampled in the northern Adriatic Sea. These individuals showed also a strong anti-CYP1A immunopositivity in hepatocytes and in the epithelium of bile ducts. This study supports the utility of MMCs as biomarkers of fish 'health status' and gives concern for a potential contaminant accumulation in ABFT.

The greater amberjack, (Risso, 1810), is a promising candidate for the diversification of European aquaculture production, but inconsistent reproduction in captivity prevents commercial production. Recent studies showed that greater amberjack confined in sea cages exhibited scarce gonad development and early interruption of gametogenic activity during the reproductive season. The aim of the present study was to improve our understanding of the observed impairment of spermatogenesis. Adult wild and captive-reared males were sampled during 3 different phases of the reproductive cycle: early gametogenesis (EARLY; late April to early May), advanced gametogenesis (ADVANCED; late May to early June), and spawning (SPAWNING; late June to July). Spermatogonial stem cells and proliferating germ cells were identified through the immunohistochemical localization of and proliferating cell nuclear antigen, respectively. Apoptotic germ cells were identified throughout the terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end labeling method. Sperm quality of captive-reared fish was evaluated using computer-assisted sperm analysis. Captive-reared males exhibited seminiferous lobules of a smaller diameter, a precocious and progressive decrease of spermatogonial mitosis, and a high level of apoptosis at the beginning of the reproductive season, concomitant with a many-fold higher 17β-estradiol plasma concentration. The motile spermatozoa percentage of captive greater amberjack was lower than in other teleosts, and a drastic decrease of spermatozoa motility duration, velocity, and ATP content occurred along the reproductive season. An abnormal increase of sperm concentration as well as an increase of dead spermatozoa occurred during the SPAWNING phase, probably because of lack of sperm hydration and ejaculation and consequent sperm ageing. The present study demonstrates the extreme susceptibility of greater amberjack to rearing stress and underscores the need for improvement of the rearing and handling procedures to ameliorate gametogenesis dysfunctions in commercial aquaculture production.

No abstract

The role of fish erythrocytes (FE) as phagocytic cells has poorly been investigated, until now. Here, we have focussed our attention on the interplay between rainbow trout (Salmo gairdneri Richardson) erythrocytes and Candida albicans (CA). At the same time, the intervention of autologous head kidney macrophages (MO) in the CA processing by FE has been studied. Data show that CA particles bind to FE, which, in turn, are able to engulf but not kill them. In the presence of MO, a decrease of FE with bound CA occurs and, in some microscopic images, FE form rosettes with MO. Phagocytosis of CA is higher in rosetting MO than in non-rosetting ones. According to our findings, it appears that FE represent a reservoir of engulfed CA and rosetting is an efficacious phenomenon of presentation of pathogens to MO, where an effective clearance of them can take place.