Laura Rizzi

Selenium interactions with essential and toxic elements in egg yolk from commercial and fortified eggs

The main objective of this work was to evaluate the interaction between selenium concentration in both commercial and Se-enriched eggs and other essential/toxic elements (Ca, Mg, Fe, Zn, Pb, and Cd), taking into account a possible synergic action of iodine. Commercial eggs were purchased from several sale points or directly from the producers (farmyard eggs). Fortified eggs were obtained by supplementing chickenfeed for 6 weeks with Se as sodium selenite (1.0 microg/g Se) or Se plus iodine (1.0 microg/g Se+3.7 microg/g I). Se in experimental egg yolks significantly increased over the basic value by 39% in the Se group and 61% in the Se+I group, suggesting that I addition may enhance Se absorption. Levels of Se in commercial yolks were identical in free-range, barn or battery eggs, but significantly lower in farmyard and higher in organic eggs where the Se content approximated that found in Se fortified eggs. A significant reduction in Cd was observed in Se+I treated yolks compared to both control and Se alone diet, thus suggesting a high sensitivity of Cd to the detoxifying effect of Se combined with I. Furthermore, Se+I supplementation was associated with a significant Zn reduction, a finding which needs clarification to avoid attempts to maximize one component affecting the levels of other essential elements.

Growth response and body composition of sharpsnout sea bream (Diplodus puntazzo) fed a high energy diet with different protein levels

Abstract A study was undertaken to determine the effect of a high energy diet with two different protein levels on growth, feed efficiency and whole body composition of sharpsnout sea bream (Diplodus puntazzo). Two isoenergetic diets (24.1–24.7 MJ Kg-1 dry weight) with two different protein levels (46.7 and 52.5% dry weight) were fed to satiety to duplicate groups of 300 fish (initial body weight 27.7 ± 0.2 g) for 94 days. At the end of the experiment, the fish fed 52.5% protein showed a statistically higher (P < 0.05) daily intake rate (DIR) of feed. Feed conversion rate (FCR) was similar among groups. Whole body composition was similar among treatments while the high energy level of the diets significantly modified lipid and moisture content in comparison with fish at the beginning of the experiment. Protein efficiency ratio (PER) and gross protein efficiency (GPE) of fish fed 46.7% protein diet were statistically higher than those for the other diet. It may be concluded that the diet with a lower protein level has given better protein utilization and a protein sparing effect but tended to result in reduced weight gain and feed intake, when compared with diet containing higher protein levels.

Digestibility and nitrogen balance of diets containing non conventional vegetable proteins fed to pigs of genetic strains suitable for outdoor systems

Abstract The study was carried out to evaluate on growing pigs kept in metabolism crates, either belonging to a “traditional” cross-breed (Duroc x Large White – DLW) or a local breed (Cinta Senese – CS), the digestibility and the nitrogen balance of non-conventional vegetable protein sources (field beans, pea and sunflower cake) when compared to soybean meal. The four diets were formulated so as to supply the same crude protein amount. CS pigs showed lower apparent digestibility coefficients (ADCs) for crude protein (81,38% vs 82,65%) and crude fibre (35,97% vs 40,65%). Nitrogen balance was more favourable in DLW pigs (32,12% vs 19,67%) which showed a higher nitrogen retention (+69%). With respect to the protein source, no differences were observed for nitrogen balance. Sunflower diet showed the higher ADC for ether extract (+20% compared with soybean diet). Crude fibre digestibility was lowered in sunflower (-33%) and field beans (-13%) diets. Sunflower and field beans diets showed the lowest gross energy digestibility coefficients. Field pea diet had the highest ADC for crude fibre (+ 12%) leading to ADCs for organic matter and gross energy comparable to those of soybean meal. It is concluded that field bean, sunflower cake and field pea could be considered as valuable non-conventional protein sources in swine nutrition.

Residues of aflatoxins B1 and M1 in different biological matrices of swine orally administered aflatoxin B1 and Saccharomyces cerevisiae

Riassunto Residui di aflatossine B1 e M1 in differenti matrici biologiche di suino alimentato con diete contenenti aflatossina B1 e Saccharomyces cerevisiae. – Le micotossine, e la aflatossina B1 (AFB1) in particolare, rappresentano da sempre un problema di sanità pubblica a livello mondiale di difficile risoluzione. Scopo del presente lavoro è stato quello di valutare le quantità di aflatossine B1 e M1, in fegato, rene, muscolo e grasso di suini che hanno assunto per 5 settimane diete sperimentalmente contaminate con 280 µg/kg di AFB1. E’ stata valutata anche la capacità adsorbente del Saccharomyces cerevisiae nei confronti di AFB1, somministrando la micotossina (280 ppb) insieme ad una dieta contenente lo 0.2% del lievito. Le quote residuali delle due aflatossine sono state determinate con metodo HPLC in fluorescenza, previa purificazione con estrazione solida (SPE). Muscolo e grasso sono risultati costantemente negativi per entrambe le micotossine, mentre i livelli rilevati in fegato e rene appaiono molto bassi per la AFB1 (valori compresi tra 0.03-0.12 ppb) e leggermente superiori per la AFM1 (valori compresi tra 0.39-0.72 ppb).

Effect of Saccharomyces cerevisiae and esterified glucomannan on residues of Ochratoxin A in kidney, muscle and blood of laying hens

Abstract The in vivo capability of Saccharomyces cerevisiae (SC), and of an esterified glucomannan (EGM) to reduce the oral bioavailability of ochratoxin A (OTA) added to a basal diet for laying hens was checked over a 12 week period. The residues of OTA in kidney, muscle and blood were studied. Eighty-four Isa Brown laying hens were divided into 6 experimental groups, fed 6 different diets: 0-0: basal diet; EGM-0: diet supplemented with 0.2% EGM; SC-0: diet supplemented with 0.2% SC; 0-OTA: diet supplemented with 0.2 ppm OTA; EGM-OTA: diet supplemented with 0.2% EGM and 0.2 ppm OTA; SC-OTA: diet supplemented with 0.2% SC and 0.2 ppm OTA. During the trial feed and water were provided ad libitum and all the animals were clinically observed. At the end of the experimental period and immediately before the hens were euthanized, blood samples were collected; kidneys, and muscle were sampled. The ochratoxin A was checked using a HPLC flourometric method. During the trial all the hens were healthy. All the biological matrices of the OTA administered hens were positive to the mycotoxin; the recorded levels were very low and decreased in the order: kidneys < blood < muscle.

Headspace analysis of volatile metabolites of Aspergillus ochraceus and Aspergillus parasiticus

Abstract Microbial spoilage is a major problem in grains or feedstuffs because it induces nutritional losses, formation of mycotoxins or potentially allergenic spores and in the end production of off-flavours. There is the need to find a method to conveniently assess the fungal growth in food and feed at every stage and after every technological process, as the detection of volatile compounds of fungi produced during primary and secondary metabolism. This paper presents the results of the analyses of some volatile compounds produced by Aspergillus ochraceus and Aspergillus parasiticus grown on maize. Moulds were cultivated on Czapek agar and on maize, previously sterilized by ultraviolet rays, in Erlenmeyer flasks closed with a Whatman bug stopper. Four samples for every substrate and mould were incubated at 26°C (A. ochraceus ) and 24°C (A. parasitucus) during 16 days. On day 8 and on day 16 of the trial, the headspace of the flasks containing the volatile metabolites was sampled with a Solid Phase-Microextration (SPME) equipped with adsorbent Carbowax PDMS fibre (Supelco, USA). Headspace samples were analysed using a gas-chromatograph HRGC- Mega 2 series 8560 (Fison Instruments, Italy) equipped with a splitsplitless injector and a flame ionisation detector (FID). Separation of compounds of interest were done using a 30m x 0.25mm I.D. mm df capillary column TR-WAX with the following parameters: injection mode was splitless for 300 sec, injector temperature was 250°C, initial oven temperature 45° C, then raised at 3° C/min to 80°C, and kept for 20 min, then it was programmed at 2°C/min to 176° C followed by the raise al 10°C/min to 240°C and then kept for 20 min. The detector temperature was 260°C. The carrier gas was helium. Volatile compounds were identified by comparing their retention times to those of pure standards. The metabolites produced on Czapek agar by A. ochraceus were 3-Octanone, 1-Hexanol, 1-Octen-3-ol and 1-Butanol, by A. parasiticus only 3-Octanone and 1-Hexanol, while the metabolites on maize were 3-Octanone and 1-Hexanol by A. ochraceus and 3-Octanone, 1-Hexanol and 1-Octen-3-ol by A. parasiticus. The incubation time did not affect off flavour production in disagreement with the results from other authors (Börjesson, 1993; Magan and Evans, 2000). The two Aspergillus species did not show different volatile metabolites when cultivated on Czapek agar. Conversely, 1-Octen-3-ol was observed on maize substrate contaminated by A. parasiticus. The results of this analytical method open many possibilities to the employment of instruments, as electronic noses, for mould control in food and feed.

Grains colonised by moulds: fungal identification and headspace analysis of produced volatile metabolites

Abstract The aim of this work was to verify if the headspace analysis of fungal volatile compounds produced by some species of Fusarium can be used as a marker of mould presence on maize. Eight samples of maize (four yellow maize from North Italy and four white maize from Hungary), naturally contaminated by Fusarium and positive for the presence of fumonisins, were analyzed to detect moisture content, Aw, volatile metabolites and an enumeration of viable moulds was performed by means of a colony count technique. Headspace samples were analysed using a gas-chromatograph equipped with a capillary column TR-WAX to detect volatile metabolites of moulds. Furthermore mac ro- and microscopic examination of the colonies was performed in order to distinguish, according to their morphology, the genera of the prevalent present moulds. Prevalent mould of eight samples was Fusarium, but other fungi, like Aspergillus, Penicillum and Mucora were observed. The metabo-ceae, lites produced by F. graminearum and F. moniliforme were Isobutyl-acetate, 3-Methyl-1-butanol and, only at 8 days, 3-Octanone. The incubation time can affect off flavour production in consequence of the presence of other moulds. Further studies on maize samples under different conditions are needed in order to establish the presence of moulds using the count technique and through the identification of volatile compounds.

The role of selenium and iodine in controlling some egg minerals

Riassunto Il ruolo del selenio e dello iodio nel controllo di alcuni minerali nell’uovo. Una prova è stata condotta su sette gruppi di galline ovaiole, alimentate con un mangime di controllo (C) o contenente: olio di lino (L), olio di pesce (F), olio ricco di DHA derivante dalla micro-alga Schizochytrium sp in presenza o meno (A) di 5 ppm di ioduro di potassio (AI) o di selenito di sodio (ASe) oppure di entrambi i sali (AISe). I contenuti di selenio e di zinco e di altri minerali sono stati valutati nei tuorli delle uova. A fine prova la concentrazione di selenio era aumentata in modo significativo (P<0,001), mentre quella dello zinco si era ridotta (P<0,05) nei tuorli dei gruppi ASe e AISe. I valori di Ca, Mn, Fe, Cu, Cd e Pb, non differirono tra i tuorli dei vari gruppi, a parte il cadmio, la cui concentrazione si era ridotta nel gruppo AISe, attestando una influenza di iodio e selenio sulla deposizione di questo metallo.