Effect of feeding a high-carbohydrate or a high-fat diet on subsequent food intake and blood concentration of satiety-related hormones in dogs.

Although studies in rodents and humans have evidenced a weaker effect of fat in comparison to carbohydrates on the suppression of food intake, very few studies have been carried out in this field in dogs. This study investigates the effects of a high-carbohydrate (HC) and a high-fat (HF) diets on subsequent food intake and blood satiety-related hormones in dogs. Diets differed mainly in their starch (442 vs. 271 g/kg dry matter) and fat (99.3 vs. 214 g/kg dry matter) contents. Twelve Beagle dogs received the experimental diets at maintenance energy requirements in two experimental periods, following a cross-over arrangement. In week 7 of each period, blood concentrations of active ghrelin, glucagon-like peptide (GLP-1), peptide YY, insulin, and glucose were determined before and at 30, 60, 120, 180, and 360 min post-feeding. The following week, intake of a challenge food offered 180 min after the HC and HF diets was recorded over two days. In comparison to the dogs on the HC diet, those on the HF diet had a higher basal concentration of GLP-1 (p = .010) and a higher total area under the curve over 180 min post-prandial (tAUC0-180 ) (p = .031). Dogs on the HC diet showed a higher elevation of ghrelin at 180 min (p = .033) and of insulin at 360 min (p = .041), although ghrelin and insulin tAUC0-180 did not differ between the two diets (p Ëƒ .10). Diet had no effect on challenge food intake (p Ëƒ .10), which correlated with the tAUC0-180 of ghrelin (r = .514, p = .010), insulin (r = -.595, p = .002), and glucose (r = -.516, p = .010). Feeding a diet high in carbohydrate or fat at these inclusion levels does not affect the feeding response at 180 min post-prandial, suggesting a similar short-term satiating capacity.

Effect of sterilization and of dietary fat and carbohydrate content on food intake, activity level, and blood satiety-related hormones in female dogs.

Animal sterilization is suggested to promote food overconsumption, although it is unknown whether this effect is mediated by variations in satiety-related hormones, which are released in response to food intake. The aim of this study was to evaluate the effect of sterilization and of the main energy-delivery nutrients, fat and nonstructural carbohydrates, on food intake, blood concentration of satiety-related hormones, and activity level in dogs. In a 2-phase experiment (phase I [Ph.I], 74 d, and Ph.II, 84 d), 12 female Beagle dogs were assigned to a control group (intact in both phases) and a sterilization group (spayed 20 d before Ph.II). In each phase, dogs received a high-carbohydrate (HC) diet (313 and 105 g/kg DM starch and fat, respectively) and a high-fat (HF) diet (191 and 213 g/kg DM starch and fat, respectively), both high in total dietary fiber (>200 g/kg DM) and providing 27% ME as protein, in 2 consecutive periods following a crossover arrangement. During each period, dogs' voluntary DMI and activity level were recorded during 5 d. Then, energy allowance was restricted to 0.7 maintenance and the level of intake of a common challenge food offered 4 h after feeding the experimental diets (challenge food intake [ChFI]) was used as an index of the satiety state of dogs. Blood concentration of active ghrelin, cholecystokinin (CCK), total peptide YY (PYY), and insulin were determined before and 15, 60, 120, 240, and 360 min after feeding. Voluntary DMI was greater ( < 0.05) in HF-fed dogs, but ChFI did not differ between diets ( > 0.10). Dogs fed the HF diet showed a lower increase of CCK at 120 ( < 0.01) and 240 min ( < 0.05), resulting in a lower ( < 0.001) total area under the curve from 0 to 240 min (tAUC). A lower PYY elevation ( < 0.05) was also found in HF-fed dogs at 120 min. Only active ghrelin concentration at 240 min and insulin tAUC correlated ( < 0.05) with ChFI (r = 0.357 and r = -0.364, respectively), suggesting a role of these hormones in appetite. Dog sterilization did not affect voluntary DMI, ChFI, or blood hormones ( > 0.10) but led to a reduced activity level compared with control dogs ( < 0.05). In summary, dog sterilization was not associated with an impaired appetite control. Feeding dogs the HF diet led to energy overconsumption and to a lower blood elevation of CCK and PYY but was not associated with a weaker satiating effect 4 h later compared with the HC diet.

Use of near-infrared spectroscopy to predict energy content of commercial dog food.

Near-infrared spectroscopy (NIRS) is used in the pet food industry for rapid assessment of several macronutrients and GE content, but there is little published data on its usefulness for evaluating GE and GE digestibility (GED) of commercial pet food. Using NIRS spectra of 71 commercial extruded dog foods and reference values determined with calorimetry and in vivo feeding trials, chemometric models were developed for GE, GED, and DE prediction. The SE and R(2) of cross-validation were 0.30 MJ/kg DM and 0.93 for GE, 2.10% and 0.82 for GED, and 0.53 MJ/kg DM and 0.92 for DE. The results indicated that NIRS provides GE, GED, and DE estimation values for dog food with an accuracy similar to that of the 2006 NRC proposed equations for use in pet food. Near-infrared spectroscopy is a fast and accurate method for predicting energy content in commercial extruded dog food, and is a useful and reliable tool to be used by the pet food industry when a wide enough calibration set is available.

Study of the effect of presence or absence of protozoa on rumen fermentation and microbial protein contribution to the chyme.

The aim of this study was to investigate the effect of presence or absence of protozoa on rumen fermentation and efficiency of microbial protein synthesis under different diets. Of 20 twin paired lambs, 1 lamb of each pair was isolated from the ewe within 24 h after birth and reared in a protozoa-free environment (n = 10), whereas their respective twin-siblings remained with the ewe (faunated, n = 10). When lambs reached 6 mo of age, 5 animals of each group were randomly allocated to 1 of 2 experimental diets consisting of either alfalfa hay as the sole diet, or 50:50 mixed with ground barley grain according to a 2 × 2 factorial arrangement of treatments. After 15 d of adaptation to the diet, the animals were euthanized and total rumen and abomasal contents were sampled to estimate rumen microbial synthesis using C(31) alkane as flow marker. Different ((15)N and purine bases) and a novel (recombinant DNA sequences) microbial markers, combined with several microbial reference extracts (rumen protozoa, liquid and solid associated bacteria) were evaluated. Absence of rumen protozoa modified the rumen fermentation pattern and decreased total tract OM and NDF digestibility in 2.0 and 5.1 percentage points, respectively. The effect of defaunation on microbial N flow was weak, however, and was dependent on the microbial marker and microbial reference extract considered. Faunated lambs fed with mixed diet showed the greatest rumen protozoal concentration and the least efficient microbial protein synthesis (29% less than the other treatments), whereas protozoa-free lambs fed with mixed diet presented the smallest ammonia concentration and 34% greater efficiency of N utilization than the other treatments. Although (15)N gave the most precise estimates of microbial synthesis, the use of recombinant DNA sequences represents an alternative that allows separate quantification of the bacteria and protozoa contributions. This marker showed that presence of protozoa decrease the bacterial-N flow through the abomasum by 33%, whereas the protozoa-N contribution to the microbial N flow increased from 1.9 to 14.1% when barley grain was added to the alfalfa hay. Absolute data related to intestinal flow must be treated with caution because the limitations of the sampling and maker system employed.

Effect of rendering on protein and fat quality of animal by-products.

This work studies the effect of rendering on quality of meat and bone meals (MBM) processed in two Spanish rendering plants according to the standard procedure recommended by 96/499/EC Directive for MBM category III. Twelve samples of raw animal by-products and their corresponding meals were analysed for chemical composition, amino acids (AA) content, FDNB-reactive lysine content, pepsin digestibility, protein dispersibility index (PDI) and fatty acids (FA) content. There was a high variation in MBM composition between and within plants, mainly in the ash and fat content. Rendering caused a decrease in the total (p < 0.05) and the essential (p < 0.01) AA content (in crude protein basis) in both plants, because of a decrease in lysine (p < 0.001), methionine (p < 0.05), threonine (p < 0.01), leucine (p < 0.01), valine (p < 0.01) and phenylalanine (p < 0.01). Besides, there was a reduction in the cystine (p < 0.001), serine (p < 0.01) and aspartic acid (p < 0.01) content. The FDNB-reactive lysine to total lysine ratio and pepsin digestibility only decreased (p < 0.001) in the plant with more severe treatment conditions, whereas the PDI increased (p < 0.05) by the process in both plants. The saturated to unsaturated FA ratio increase on average from 0.73 to 0.88 after rendering, because of the decrease in both linoleic and linolenic acids content and the increase in palmitic and stearic acids content. The results indicate that rendering has negative effects on protein and fat quality of MBM. Variability between and within plants is attributed to differences in raw material, processing conditions and fat removing efficiency. Therefore, a continuous monitoring is recommended to assure the quality of each batch before use.

In vitro rumen fermentation of the tropical grass Pennisetum purpureum and mixtures with browse legumes: effects of tannin contents.

The fermentation of Pennisetum purpureum, alone (PP) or substituted with 0.30 of the tanniferous legumes Acacia cornigera (AC), Albizia lebbekoides (AL), Leucaena leucocephala (LL) and the saponin-rich Enterolobium cyclocarpum (EC) was studied in vitro, in presence or absence of polyethylene glycol (PEG) as tannin binder. Inactivation of tannins with PEG increased (p < 0.05) gas production with AL and LL from 8 and 12 h to the end of the incubation period respectively. When PEG was added, LL and AC promoted a higher (p < 0.05) gas volume than PP in the first 12 h incubation, and there were not differences between PP and AL. Substrate mixtures reduced (p < 0.05) methane volume produced compared with PP, but this was not related to PEG inclusion (p > 0.10). There was a trend (p = 0.06) for a higher 48 h bacterial attachment to the substrate when incubated without PEG. The decrease in fermentation of EC from 12 h incubation onwards could be associated with a negative mid-term effect of saponins over cellulolytic bacterial activity. It is concluded that the effects of tannins on microbial fermentation of mixed forage substrates are variable, depending on their nature, but do not have a marked impact on bacterial adhesion or methane production.

Prediction of digestible protein content of dry extruded dog foods: comparison of methods.

The aim of this study was to check the accuracy of laboratory methods to predict the apparent protein digestibility (CPd, %) and digestible protein content (DP, g/kgDM) of dog foods, avoiding the use of experimental animals in digestion trials. Twenty-eight commercial dry extruded dog foods were tested by three different methodologies: an adaptation of the in vitro incubation method described by Hervera et al. (J Anim Physiol Anim Nutr 2007, 91: 205) for estimation of digestible energy of commercial dog foods, a modification of the pH drop methodology proposed by Hsu et al. (J Food Sci 1977, 42: 1269) for protein evaluation of human foods and the Near Infra Red Spectroscopy (NIRS) technology. All the methods assessed revealed very good, similar accuracy in the prediction of DP content either using the in vitro method (r = 0.99; RSD = 6.76; CV = 2.31%), the pH drop method (r = 0.99; RSD = 6.94; CV = 3.02%) or the NIRS (R2 = 0.96; SECV = 10.50) method, although the in vitro digestion method showed the highest accuracy approach of in vivo crude protein apparent digestibility: CPd in vitro (r = 0.81; RSD = 2.01; CV = 2.41%); CPd pH-drop (r = 0.78; RSD = 2.48; CV = 2.98%) and NIRS (r(2)cv = 0.53; SECV = 2.37).

Prediction of digestible energy value of extruded dog food: comparison of methods.

The proposal of National Research Council (NRC), based on the use of modified Atwater factors, is nowadays the widely used method to estimate digestible energy (DE) content of pet foods. Recently, alternative methods have been suggested for predicting energy content of commercial canine dry food. Factorial equations including food fibre content as estimator, in vitro digestions methods or near-infrared spectroscopy (NIRS) techniques have been considered as good approaches to predict the energy content of dog foods. The aim of this study was to compare the accuracy of some of those estimation methods. Seventeen samples of commercial extruded dog food were used to validate and compare some estimation methods of energy digestibility (Ed, %) and DE value [MJ/kg dry matter (DM)]. The apparent Ed and DE of each food were previously determined by in vivo trials. In vivo Ed and DE of foods ranged from 79.30% to 91.05% and from 16.25 to 21.82 MJ/kg DM, respectively, and their crude fibre (CF) content ranged from 0.72% to 3.28% (in DM base). The % Ed of each sample was estimated by the factorial equation (% Ed = 91.2 - 1.43 x CF %) and by the in vitro digestion method [% Ed(in vitro) = -2.45 + 0.98 organic matter (OM) disappearance(in vitro)%]. The set of samples also was analysed by NIRS, using a calibration equation developed from a set of 69 samples of commercial extruded dog food (0.76 and 0.89 cross-validation r(2) and 2.33 and 0.61 cross-validation SE for Ed and DE respectively). The in vitro method gave better estimations of Ed in vivo than NIRS and factorial methods, although all the methods assessed showed a very good and similar accuracy in the prediction of DE value. These three methods showed a slight better accuracy than that previously proposed by the NRC. To consider constant digestibility values of nutrient content of food can result in bias and error in the estimated energy values. The alternative prediction methods used in this study take into account differences of ingredient composition and availability of nutrients of different extruded dog foods thus could be better systems of valuating energy content in a wider range of different kind of foods than in use method.

Prediction of digestible energy content of extruded dog food by in vitro analyses.

The aim of this study was to develop a simple and reproducible in vitro method for predicting the apparent energy digestibility of dry extruded dog foods. The proposed method is based on the two-step multienzymatic incubation assay described by [Boisen, S., 1991: In Vitro Digestion for Pigs and Poultry, M. F. Fuller (ed.). CAB International, Wallingford, 135-146], with some modifications adapted to dogs' digestion characteristics. The method consisted in two consecutives incubations, first one during 2 h with pepsin (10 mg/g of food sample) in acid pH and second one during 4 h with pancreatin (100 mg/g of food sample). The undigested residue obtained was collected in a filtration unit and then dried and ashed. The in vitro percentage of organic matter disappearance (in vitro dOM) of 54 dry extruded commercial dog foods was determined and used as predictor of the in vivo apparent organic matter (in vivo dOM) and energy digestibility (in vivo dE) and digestible energy (DE) content. There was a close linear relationship between the in vivo dOM and dE [r(2) = 0.95, residual standard deviation (RSD) = 1.05 and coefficient of variation (CV) = 1.2%] and also between the in vitro and in vivo dOM (r(2) = 0.92, RSD = 1.38 and CV = 1.6%), even if the in vitro dOM overestimated on average by 4% the in vivo dOM. When the in vitro dOM was used to predict the in vivo dE, the relationship between both variables was defined by the equation: in vivo dE (%) = -2.45 + 0.98 +/- 0.04x in vitro dOM (%), (r(2) = 0.92, RSD = 1.25 and CV = 1.5%). In addition, a close relationship between the in vivo and predicted DE (estimated dE x gross energy determined calorimetrically) was found (r(2) = 0.97, RSD = 0.26 and CV = 1.4%). The accuracy of DE content prediction using the proposed in vitro method was higher than that obtained when the DE content of the same set of samples was predicted by the equation proposed by the NRC (1985) (r(2) = 0.76, CV = 4.5%) and also slightly higher than that obtained when using the equation proposed by NRC (2006) (r(2) = 0.95, CV = 2.1%).

Effect of extruding the cereal and/or the legume protein supplement of a compound feed on in vitro ruminal nutrient digestion and nitrogen metabolism.

An experiment was performed to evaluate the effect of extruding the cereal and/or the protein supplement of a compound feed for intensively reared calves on ruminal N metabolism using an in vitro culture system. A conventional compound feed was produced without extruding [treatment non-extruded (NE)], with the cereal blend extruded (CE), with the protein blend extruded (PE) and with both cereal and protein blends extruded (CPE). Four experimental diets, consisted of 0.90 of each experimental compound feed and 0.10 barley straw were assessed using dual-flow continuous-culture fermenters. (15)N infusion as ammonia sulphate was used to label the microbial population. Average NH(3) concentration in fermenter effluents ranged from 270 mg/l with diet NE to 69 mg/l for diet CPE (p < 0.05) and volatile fatty acid concentrations ranged from 161 mm in diet PE to 130 mm in diet CPE (p < 0.05). Diets PE and CPE showed a lower true organic matter degradability (49.5% and 48.2%) than NE and CE (52.8% and 52.2%). Non-ammonia nitrogen flow in effluents was highest on diet CPE, intermediate on diets CE and PE and lowest on diet NE (p < 0.01), reflecting the differences in dietary N flow and dietary protein degradability (71.2%, 63.7%, 61.2% and 50.0%, respectively, for NE, CE, PE, CPE; p < 0.001). In contrast, microbial protein synthesis efficiency was lower for treatments including the cereal blend extruded, although the resulted differences were only significant (p < 0.001) for CPE diet.

Effect of combinations of organic acids in weaned pig diets on microbial species of digestive tract contents and their response on digestibility.

The effect of combinations of organic acids on digestive microbial population and total tract digestibility of piglets was studied. Thirty 19-21 days weaned pigs (5.4 +/- 0.23 kg, six pigs per treatment) were given a mixed feed with 10 ml water/kg (CTL) or 200 mEq/kg of formic acid (FOR), 1:1 formic:fumaric (FOFU), 1:1 formic:lactic (FOLA) or 2:1 formic:lactic (2FOLA). After 6-8 days, animals were slaughtered. In gastric contents, pH was higher (p = 0.01) with FOFU and lactobacilli tended (p = 0.08) to be lower with FOFU than CTL and FOLA, but coliform counts did not differ (p = 0.14). Acetate proportion was lower (p = 0.03), and propionate (p = 0.05) and butyrate (p = 0.01) higher, with FOFU than CTL, FOLA and 2FOLA. Intestinal coliform counts were higher (p = 0.03) with CTL than FOLA and 2FOLA, but there were no differences on lactobacilli. In intestinal contents, acetate tended (p = 0.06) to be lower with FOR than FOLA and 2FOLA, and butyrate was higher (p = 0.001) with FOR. Although not significantly, dry matter digestibility was 0.03-0.05 lower with CTL than with the other treatments. Combinations of organic acids in piglet diets modify gastric and intestinal microflora, the mixtures of formic:lactic appearing as the most interesting.

In situ ruminal degradability and intestinal digestion of raw and extruded legume seeds and soya bean meal protein.

An experiment was performed to evaluate the effect of extrusion and carbohydrate addition on rumen degradation and intestinal digestion of raw legume seeds and solvent extracted soya bean meal (SBM) protein. Whole soya beans (WSB) without or with maize added (75:25) (WSB-M), peas, lupins and SBM were extruded at 140 degrees C. Protein rumen degradation and intestinal digestibility of unprocessed and extruded protein sources were measured by in sacco and mobile bag procedures, respectively, in two dairy cows cannulated in rumen and duodenum. Between 12 and 15 polyester bags with 4 g of each protein source were incubated in rumen for 12 h and the residues, pooled by feed, were introduced into the duodenum in small nylon bags after pre-incubation in a pepsin solution, and recovered from faeces the day after. Extrusion significantly (p < 0.001) reduced N degradation of all protein sources, from 98.1%, 91.6%, 90.5% and 64.8% to 53.1%, 73.8%, 70.3% and 44.2% for peas, lupins, WSB and SBM respectively. The addition of maize to WSB strengthened the effect of extrusion on rumen N degradation, from 88.2% to 52.6%. Residues from rumen incubation of extruded feeds showed a higher (p < 0.001) intestinal N digestibility except for SBM (87.0%, 82.9%, 66.3%, 85.0% and 97.2%, and 99.1%, 95.8%, 96.8%, 97.8% and 98.7%, respectively, for non-extruded and extruded, peas, lupins, WSB, WSB-M and SBM). In conclusion, the extrusion of studied legume seeds and SBM promotes a clear and significant increase of their metabolizable protein value, particularly in peas, and the inclusion of a source of carbohydrates before extrusion increase this response.

Energy evaluation of extruded compound foods for dogs by near-infrared spectroscopy.

Near-infrared reflectance spectroscopy (NIRS) was used to predict the chemical composition, apparent digestibility and digestible nutrients and energy content of commercial extruded compound foods for dogs. Fifty-six foods of known chemical composition and in vivo apparent digestibility were analysed overall and 51 foods were used to predict gross energy digestibility and digestible energy content. Modified partial least square calibration models were developed for organic matter (OM), crude protein (CP), ether extract (EE), crude fibre (CF), nitrogen free extracts (NFE) and gross energy (GE) content, the apparent digestibility (OMD, CPD, EED, NFED and GED) and the digestible nutrient and energy content (DOM, DCP, DEE, DNFE and DE) of foods. The calibration equations obtained were evaluated by the standard error and the determination coefficient of cross-validation. The cross-validation coefficients of determination (R) were 0.61, 0.99, 0.91, 0.96, 0.94 and 0.92 for OM, CP, EE, CF, NFE and GE, the corresponding standard error of cross-validation (SECV) being 5.80, 3.51, 13.35, 3.64 and 16.95 g/kg dry matter (DM) and 0.29 MJ/kg DM respectively. The prediction of apparent digestibility was slightly less accurate, but NIRS prediction of digestible nutrient (g/kg DM) and DE (MJ/kg DM) gave satisfactory results, with high R (0.93, 0.97, 0.93, 0.83 and 0.93 for DOM, DCP, DEE, DNFE and DE respectively) and relatively low SECV (11.55, 6.85, 12.14 and 22.98 g/kg DM and 0.47 MJ/kg DM). It is concluded that the precision of NIRS in predicting the energy value of compound extruded foods for dogs is similar or better than by proximate analysis, as well as being faster and more accurate.

A comparison of purine derivatives excretion with conventional methods as indices of microbial yield in dairy cows.

Three multiparous, ruminally and duodenally cannulated Holstein-Friesian milking cows (558 +/- 14 kg BW) with a mean milk yield of 19.9 +/- 1.4 kg/d in their 4th mo of lactation were fed a mixed diet of forage and concentrate at 100, 85, and 75% of ad libitum intake in a 3 x 3 Latin square design. Duodenal digesta flow was estimated using the dual-phase technique in which Cr-EDTA and Yb-acetate were used as liquid and solid markers, respectively. Microbial N (MN) was estimated using the duodenal flow of purine bases (PB); bacterial isolates from the rumen liquid and solid phases were used as references. Additionally, duodenal flow of PB and MN were estimated indirectly using the excretion of purine derivatives (PD) in urine and milk. Duodenal flow of PB and derived MN tended to decrease with feed restriction (from 258 to 154 mmol/d and 123.5 to 74.4 g/d, respectively). Estimates of PB and MN based on urinary PD showed the same trend, and decreases in PB (from 314 to 266 mmol/d, using LAB) were statistically significant. Using LAB, efficiencies of microbial protein synthesis in the ad libitum treatment were 12.9 and 17.0 g of MN/g of organic matter apparently digested in the rumen when estimated using duodenal PB and urinary excretion of PD, respectively. Urinary excretion of PD closely reflected changes in duodenal flow of PB as a result of feed restriction.

Prevalence of herpesvirus DNA in MS patients and healthy blood donors.

OBJECTIVES: The aim of this study is to determine the DNA prevalence of different members of Herpesviridae in multiple sclerosis (MS) patients and to describe the possible effect of beta-interferon treatment on such prevalence. MATERIAL AND METHODS: With a nested polymerase chain reaction (PCR) assay we have studied the DNA of the peripheral blood mononuclear cells (PBMCs) of 204 whole blood samples, [102 from patients with relapsing-remitting MS (RRMS), of which 62 were treated with beta-interferon, and 102 from healthy blood donors]. RESULTS: We only found a statistically significant difference for human herpesvirus type 6 (HHV-6) DNA prevalence (P < 0.0001): HHV-6 is 2.26 times more frequent in MS patients than in healthy donors. There was no difference in the HHV-6 prevalence between beta-interferon treated and untreated patients. CONCLUSION: 1. Among the herpesviruses, HHV-6 was the only one showing altered prevalence. This either indicates that HHV-6 is involved in the pathogenesis of MS, or it simply indicates that MS influences latency or reactivation of HHV-6 without any direct involvement of HHV-6 in the disease process of MS. 2. Treatment with beta-interferon does not make a difference on the DNA prevalence of the herpesviruses studied in our MS patients.

The effect of crude fibre on apparent digestibility and digestible energy content of extruded dog foods.

The apparent digestibility of nutrients and energy of 38 commercial dry extruded dog foods was measured using six adult (2 to 3 year-old) female Beagles. Diets contained [in g/kg dry matter (DM)]: 164-360 crude protein (CP); 79-261 ether extracts (EE); 8-33 crude fibre (CF) and 318-585 nitrogen free extracts (NFE). Apparent energy digestibility ranged from 77.3 to 91.6%, and was closely related to CF content (r=-0.85), yielding the resultant equation: GED (%)=94.00 - 4.04 x CF (% DM). The estimation of digestible energy content of foods from digestibility coefficients predicted from the above equation and gross energy measured or estimated from the Weende fractions, provides a more accurate prediction of experimental values than the Atwater approach followed by the National Research Council and the Association of American Feed Control Officials.

Urinary energy losses in dogs fed commercial extruded foods.

Energy and nitrogen losses in the urine were recorded in 134 individual balances with adult (1- to 2-year-old) female Beagles that were fed 23 dry extruded dog foods ranging in crude protein (CP) content from 242 to 360 g/kg dry matter. The energy equivalent of urinary nitrogen was estimated as 33.9 kJ/g N. Both energy losses in the urine corrected for the nitrogen balance, and the metabolizable energy (MEn): digestible energy (DE) ratio were found to be closely related to diet CP content (r : 0.851 and 0.820). The MEn content of extruded dog foods can be accurately calculated from the DE content, either by subtracting 4.59 MJ/kg CP or estimating the MEn/DE ratio from the food CP content by the following equation: MEn/DE=0.98 - 3.44 +/- 0.517 x CP (kg/MJ DE).

[Deep neck infections]. / Infecciones cervicales profundas.

Deep neck infections are charts potentially dangerous though of low incidence. Few times linked to severe complications, as mediastinitis, of high morbi-mortality. They call for emergency procedures combining neck and thorax surgery, if there is a mediastinitis, with a broad-spectrum antibiotherapy within an Intensive Care Unit, with the aim of the maintain the patients's equilibrium constant till their reestablishment. We report 3 cases seen in a term lesser than one year at the Universitary Hospital of Salamanca. The 3 presented with thoracic complication because the spread of the neck's infect. Nevertheless the pending severity all three survived. We emphasize the necessity of realizing the pressing surgery and the utilitarianism of broad-spectrum antibiotherapy as key elements in order to get the patient's reestablishment. Literature review on the subject.