Giacomo Biagi

A new in vitro method to evaluate digestibility of commercial diets for dogs

Abstract The aim of the present study was to develop a new in vitro method for evaluating the digestibility of commercial diets for dogs. First, in order to develop the in vitro method, the digestibility of four commercial diets for dogs was evaluated through several in vitro trials and results were compared with those that were retrieved from the literature. The in vitro method that was developed consists of two incubation phases, a first lasting 2h and taking place in the presence of pepsin, gastric lipase and HCl (gastric phase) and a second 4h one with pancreatin and bile salts (intestinal phase). Later, digestibility of 16 extruded diets for dogs was evaluated both in vivo with adult dogs and in vitro. There was a close linear relationship between in vivo total tract and in vitro dry matter digestibility (r2u2009=u2009.81), whereas accuracy of crude protein digestibility using the in vitro method was lower (r2u2009=u2009.51). Linear regression accuracy for ether extract and starch digestibility was low, but the digestibility results obtained with the in vitro method (95.3 and 98.7% for ether extract and starch, respectively) were very close to those from the in vivo trial (average digestibility of ether extract and starch was 94.8 and 99.1%, respectively). The present in vitro method has proved to be a relatively simple, quick procedure for predicting the digestibility of commercial diets for dogs. The utilisation of such a method may significantly reduce the need for in vivo digestion trials with dogs.

In vitro influence of dietary protein and fructooligosaccharides on metabolism of canine fecal microbiota

BackgroundThe present in vitro study investigated whether the utilization of fructooligosaccharides (FOS) may influence canine fecal microbial population in presence of diets differing in their protein content and digestibility. Fresh fecal samples were collected from five adult dogs, pooled, and incubated for 24xa0h with the undigested residue of three diets: 1, Low protein high digestibility diet (LP HD, crude protein (CP) 229xa0g/kg); 2, High protein high digestibility diet (HP HD, CP 304xa0g/kg); 3, High protein low digestibility diet (HP LD, CP 303xa0g/kg) that had been previously subjected to enzymatic digestion. In the in vitro fermentation study, there were six treatments: 1) LP HD; 2) HP HD 3) HP LD; 4) LP HDu2009+u2009FOS; 5) HP HDu2009+u2009FOS; 6) HP LDu2009+u2009FOS. Fructooligosaccharides were added at the final concentration of 1.5xa0g/L. Samples of fermentation fluid were collected at 6 and 24xa0h of incubation.ResultsValues of pH were reduced by FOS at 6 and 24xa0h (Pu2009<u20090.001); conversely, low protein digestibility and high dietary protein level resulted in higher pH at both sampling times (Pu2009<u20090.001). At 24xa0h, FOS lowered ammonia (−10xa0%; Pu2009<u20090.001) and resulted (Pu2009<u20090.05) in higher concentrations of total volatile fatty acids (VFA) (+43xa0%), acetic acid (+14xa0%), propionic acid (+75xa0%) and n-butyric acid (+372xa0%). Conversely, at 24xa0h, low protein digestibility resulted (Pu2009<u20090.01) in lower concentrations of acetic acid (−26xa0%), propionic acid (−37xa0%) and total VFA (−21xa0%). Putrescine concentrations were increased at 6 and 24xa0h of fermentation by low protein digestibility (+21 and 22xa0%, respectively; Pu2009<u20090.05) and FOS (+18 and 24xa0%, respectively; Pu2009<u20090.01). After 24xa0h of fermentation, high dietary protein level resulted in lower counts of lactobacilli and enterococci (−0.5 and −0.7 log cells/mL, respectively; Pu2009<u20090.05) whereas low protein digestibility tended to increase counts of C. perfringens (+0.2 log cells/mL; Pu2009=u20090.07).ConclusionsResults from the present study showed that diets rich in protein may exert negative influences on the canine intestinal ecosystem, slightly increasing the presence of ammonia and reducing counts of lactobacilli and enterococci. Moreover, the presence of poorly digestible protein resulted in lower concentrations of VFA. Conversely, administration of FOS may improve metabolism of canine intestinal microbiota, reducing ammonia concentrations and enhancing VFA production.

The combined effect of Sango sprout juice and caloric restriction on metabolic disorders and gut microbiota composition in an obesity model

Abstract The main purpose of this study was to compare the benefits of SSJ supplementation in obese rats with those achieved only by switching the alimentary regimen from high-fat (HFD) to the regular one (RD) in liver, ileum and prostate. Furthermore, changings in caecal chime microbiota were investigated. SSJ was administered to rats in combination with a RD (HFD-RDu2009+u2009SSJ). The switch from HFD to RD led to a weight loss of almost 9.8u2009g, and the total cholesterol was found to be significantly lower. In the HFD-RDu2009+u2009SSJ group, all values were improved compared with the HFD control, and the weight decrement was higher (−23.29u2009g) with respect to HFD-RD. HFD led to a widespread increment of oxidative stress (OS) markers in liver, ileum and prostate. SSJ has shown to improve the results achieved by the suspension of HFD and it has proven effective wherever the only switch in diet regimen failed.

Influence of dietary protein and fructooligosaccharides on fecal fermentative end-products, fecal bacterial populations and apparent total tract digestibility in dogs

BackgroundFeeding dogs with diets rich in protein may favor putrefactive fermentations in the hindgut, negatively affecting the animal’s intestinal environment. Conversely, prebiotics may improve the activity of health-promoting bacteria and prevent bacterial proteolysis in the colon. The aim of this study was to evaluate the effects of dietary supplementation with fructooligosaccharides (FOS) on fecal microbiota and apparent total tract digestibility (ATTD) in dogs fed kibbles differing in protein content. Twelve healthy adult dogs were used in a 4u2009×u20094 replicated Latin Square design to determine the effects of four diets: 1) Low protein diet (LP, crude protein (CP) 229xa0g/kg dry matter (DM)); 2) High protein diet (HP, CP 304xa0g/kg DM); 3) Diet 1u2009+u20091.5xa0g of FOS/kg; 4) Diet 2u2009+u20091.5xa0g of FOS/kg. The diets contained silica at 5xa0g/kg as a digestion marker. Differences in protein content were obtained using different amounts of a highly digestible swine greaves meal. Each feeding period lasted 28 d, with a 12 d wash-out in between periods. Fecal samples were collected from dogs at 0, 21 and 28 d of each feeding period. Feces excreted during the last five days of each feeding period were collected and pooled in order to evaluate ATTD.ResultsHigher fecal ammonia concentrations were observed both when dogs received the HP diets (pu2009<u20090.001) and the supplementation with FOS (pu2009<u20090.05). The diets containing FOS resulted in greater ATTD of DM, Ca, Mg, Na, Zn, and Fe (pu2009<u20090.05) while HP diets were characterized by lower crude ash ATTD (pu2009<u20090.05). Significant interactions were observed between FOS and protein concentration in regards to fecal pH (pu2009<u20090.05), propionic acid (pu2009<u20090.05), acetic to propionic acid and acetic + n-butyric to propionic acid ratios (pu2009<u20090.01), bifidobacteria (pu2009<u20090.05) and ATTD of CP (pu2009<u20090.05) and Mn (pu2009<u20090.001).ConclusionsA relatively moderate increase of dietary protein resulted in higher concentrations of ammonia in canine feces. Fructooligosaccharides displayed beneficial counteracting effects (such as increased bifidobacteria) when supplemented in HP diets, compared to those observed in LP diets and, in general, improved the ATTD of several minerals.

Digestibility, toxicity and metabolic effects of rapeseed and sunflower protein hydrolysates in mice

Abstract The digestibility (in vitro), toxicity and metabolic effects of rapeseed (RPH) and sunflower (SPH) protein hydrolysates have been evaluated in a murine animal model. The enzyme Alcalase® was employed to obtain a mild enzymatic hydrolysis of rapeseed and sunflower defatted seed meals (DSM) protein isolates. Both hydrolysates showed higher in vitro digestibility than the respective DSM, presumably as a consequence of the hydrolysis process that they had undergone. In vivo, RPH and SPH were well tolerated. Body and organ weights, biochemical blood parameters from treated male mice were comparable to controls. Food intake was regular in RPH and SPH animals, suggesting a good palatability of the hydrolysates. Not relevant perturbations of the principal hepatic and renal drug metabolism enzymes were observed in RPH or SPH mice. In conclusion, protein hydrolysates from sunflower and rapeseed DSM did not determine relevant toxicological effects; therefore, they could be considered as alternative protein sources and/or food ingredients.

An in vitro evaluation of the effects of a Yucca schidigera extract and chestnut tannins on composition and metabolic profiles of canine and feline faecal microbiota

ABSTRACT The in vitro effect of a Yucca schidigera extract (YSE) and tannins from chestnut wood on composition and metabolic activity of canine and feline faecal microbiota was evaluated. Four treatments were carried out: control diet, chestnut tannins (CT), YSE and CT + YSE. The YSE was added to canine and feline faecal cultures at 0.1 g/l, while CT were added at 0.3 g/l for a 24-h incubation. A total of 130 volatile compounds were detected by means of headspace-solid phase microextraction gas-chromatography/mass spectrometry analyses. Several changes in the metabolite profiles of fermentation fluids were found, including a decrease of alcohols (−19%) and esters (−42%) in feline and canine inoculum, respectively, which was due to the antibacterial properties of tannins. In canine inoculum, after 6 h, YSE + CT caused lower cadaverine concentrations (−37%), while ammonia (−4%) and quinolone (−27%) were reduced by addition of CT. After 24 h, the presence of CT resulted in a decrease of sulphur compounds, such as dimethyl sulphide (−69%) and dimethyl disulphide (−20%). In feline faecal cultures, after 6 h, CT lowered the amount of indole (−48%), whereas YSE tended to decrease trimethylamine levels (−16%). Both in canine and feline inoculum, addition of CT and, to a minor extent, YSE affected volatile fatty acids patterns. In canine faecal cultures, CT exerted a marginal inhibitory effect on Escherichia coli population (−0.45 log 10 numbers of DNA copies/ml), while enterococci were increased (+2.06 log 10 numbers of DNA copies/ml) by YSE. The results from the present study show that YSE and tannins from chestnut wood exert different effects on the composition and metabolism of canine and feline faecal microbiota. In particular, the supplementation of YSE and tannins to diets for dogs and cats may be beneficial due to the reduction of the presence of some potentially toxic volatile metabolites in the animals’ intestine.