Carne ed il pesce constitute un'importante source proteica nella dieta dei piccoli animali domestici, ma la loro digeribilità non è semper connoisseur in modo easustivo. This study has evaluated the protein digestibility and biodisponibility of the amino acids (AA) of various animal protein sources comparing 3 different methods in vitro and in vivo.
Negli ultimi anni stiamo asistendo ad un crescente interesso da parte dei proprietari di animali alla qualità del cibo ad essi destinato; The process of humanizing animals and the greater interest in their health have contributed to shifting the demand for always more products of good quality and from which they can easily understand the origin.
In the literature, some works related to the composition of different protein sources of animal origin have been published, while the publications relative to the digestibility of the same are scarce: in particular, at the moment when the study in question was conducted, there were no comparative studies on the digestibility of animal protein sources of mammalian, avian and fish origin.
In this study, the differences in composition and protein digestibility of three meat sources (beef loin, pork loin, chicken breast) and two fish sources (hake filet and salmon filet) were analyzed. It is chosen to analyze the nutritional composition and the digestibility of protein matrices in detail using three methods:
- IDEA kit (enzyme kit)
- utilizzo di galli tiflectomizzati
- utilizzo di cani incannulati a livello ileale.
Sono stati selecti di carne di buona qualità e con un contenuto di fatsi relatively low, e filletti di luzzo e filletti di salmone rosa private della pelle. All the substrates once obtained were frozen, without the use of preservatives, and subsequently they were dried in a desiccator at a low temperature (6 hours at 71 °C), then they were refrigerated and sent to the University of Illinois (Urbana), where they underwent a fine grinding to obtain particles of 2 mm.
Tutti i substrati sono stati analizati per ottenere il loro valore in sostanza secca, sostanza organica e ceneri, mediante methodiche approvate AOAC (2006). Sono stati rilevati per ciascuno di essi: proteine grezze, fatsi grezze, fibra totale, energia lorda, le concentrazioni di amine biogene, fatty acids a catena lunga, aminoacidi e collagene.
Sistema IDEA: each substrate has been hydrolyzed by a mixture of enzymes present in the IDEA commercial enzyme kit. Il contenuto proteico hydrolizzato has liberated gli alfa-AA, che loro volta sono stati miscelati e legati a un marker (ortophthaldeialdeide - OPA). Attraverso l'uso di uno spectrofotometro è stata valutata l'absorbanza di OPA, ed in questo modo indirectly si è ottenuta la quantita di AA liberated dall'idrolisi enzimatica.
Sistema del saggio da galli tiflectomizzati: following the method described by Sibbald (1979), 20 roosters were subjected to tiflectomia at the age of 25 weeks, after a few weeks of healing, the roosters were subjected to 24 hours of fasting and then intubation of the gozzo, and each one received 30 g of each of the protein substrates (4 roosters were used for each of the 5 substrates in the studio). I galli successively sono stati sottoposti a digiuno per 48 ore, e in questo lasso di tempo le deiezioni da essi produced sono state raccolte su un trayo di plastica posto sotto ciascansa gabbia. The obtained samples were lyophilizati, pesati, macinati a 0.25 mm e per ognuno di essi si è quantificato il contenuto in AA.
Sistema con cani incannulati a livello ileale: sono stati movistais 5 canni da caccia, incannulate a livello ileale secondo la procedure di Walker et al. (1994), ognuna aveva un box individuale con condizioni ambientali controlled ed uguali per tutte.
Sono state formulated 5 estrus diets with a typical formulation of a food of good quality (30% protein, 20% fat, integration of minerals and vitamins), each containing the primary protein source, only one of the 5 sources in the studio. The diet was administered to each dog in the following way: water at will and twice a day 150 gr of food, to which chromic oxide (0.2 %) was added as a marker of digestibility.
Following a regular collection schedule for each dog, samples of ileal content and fecal samples were collected 3 times a day for 4 days. These samples have been conserved and processed in order to obtain information on the digestibility of the protein content, the presence of biogenic amines, and other characteristics found in previous methods.
The results of the analysis of this work indicated that:
- le concentrazioni dei singoli AA erano simili in tutti i substrati proteici, tuttiva la lisina era superiore del 26% nel filletto di merluzzo rispetto alla lonza di maiale e alla lombata di manzo;
- the concentrations of AA essential and AA non essential in the filet of cod were superior respectively of 15% and 22% compared to those of the lonza di maiale;
- la concentración di grasso idrolizzato era maggiore nella lombata di manzo e in quella di maiale;
- le concentrations of acidi grassi polynsaturi and acidi grassi-3 erano maggiori nei filetti di merluzzo e salmone;
- the total alimentary fiber, una misura della concentrato di tessuto connettivo, was low for all the substrates, indicating the good quality of the carne and pesce tags utilized;
- The values of digestibility of the AA of the substrates with the IDEA kit and those obtained with the digestion in galli tiflectomizzati were consistent between them, in general the digestibility was similar between all the substrates, but the cod filet showed the greatest digestibility (71%).
- nel saggio sui cani incannulati a livello ileale, the digestibility of raw protein has obtained high values for all substrates, probably because the cuts of meat and fish were all of good quality, and this has minimized the effect of the difference in the content of connective tissue between the substrates (a factor that normally negatively influences digestibility).
In conclusion, i results of this work demonstrated that the substrates in analysis were different between them per composition, but the digestibility instead was similar for all protein fonts used. In particolare, nelle prove sui cani, i valori di digestibilità ileale non hanno riportato differenze sigificante tra le varie fonti proteiche con valori compresi tra 88,9% del petto di pollo al 90,5% del filetto di luzzo e lonza di maiale. Anche i valori di digestibilità totale nel cane non hanno dimosto differenze tra le diverse fonti proteiche, con valori compresi tra 94.4% e 94.8%.
