Enteric function in cats after subtotal colectomy for treatment of megacolon

The enteric function of four cats that had undergone subtotal colectomy for megacolon was compared with that of four normal cats. All cats were fed the same diet before and during the study. History, physical condition, body weight, blood chemistry panel, fasting and postprandial serum bile acids, serum cobalamin concentration, serum folate concentration, fecal weight, fecal water content, fecal fat content, fecal osmolality and electrolyte concentration, quantitative anaerobic fecal bacterial culture, partial thromboplastin time, prothrombin time, breath hydrogen concentration, urinary calcium, phosphorus and electrolyte concentrations, and abdominal radiographic examination with air contrast studies (pneumocolon) were examined. The four cats treated surgically were healthy and thriving and, in general, enteric function was similar to the controls. Bowel movements occurred only slightly more frequently with no significant differences in fecal volume or water content. Serum cobalamin concentrations were significantly higher in cats treated surgically. Fecal sodium concentrations were high and fecal potassium concentrations were low. Results of this study did not show any significant subclinical evidence of abnormal bowel function in cats after subtotal colectomy.

Repeated noninvasive measurement of gastrointestinal transit in rats

A technique for repeated and noninvasive measurement of oro-cecal transit time in rats and other small animals is described. It is based on the incomplete digestion of carbohydrates such as lactose fed orally to the animals. Since the activity of the enzyme lactase is low in almost all species, lactose is fermented by colonic bacteria after it arrived in the cecum, thus producing hydrogen. Hydrogen is delivered to the lungs via the circulation and exhaled by the animal. An increase in breath hydrogen measured by means of an electrochemical cell or a gas-chromatograph indicates the arrival of the nutrient bolus in the cecum. The method can be used repeatedly in individual animals under various experimental conditions such as investigations of stress effects on gastrointestinal transit.

A method for direct measurement of systemic uptake and elimination of volatile organics in small animals

A method was developed which was suitable for toxicokinetic studies requiring direct, repetitive sampling of blood and breath during exposures of small animals to volatile chemicals. Anesthetized male Sprague-Dawley rats were tracheostomized, and a specially fabricated one-way breathing valve was inserted directly into the trachea, in order that the inhaled and exhaled breath streams could be separated and independently sampled. The desired concentration of 1,1,1-trichloroethane was generated in a gas sampling bag, which was connected to the inlet side of the valve for inhalation exposures. Rats dosed with 1,1,1-trichloroethane by gavage inhaled ambient air through the valve. A pneumotachograph was positioned in the influent air stream to measure respiration. Respiratory rate, minute volume, and core temperature were continuously recorded on a physiograph. Samples of inspired and expired air were periodically collected from sampling ports immediately adjacent to the breathing valve and were analyzed for their 1,1,1-trichloroethane content by gas chromatography. Using this system, it was possible to determine percentage systemic uptake at any given time and to monitor cumulative uptake (i.e., total dose received) over the course of inhalation exposures. Alveolar concentrations were calculated by taking into account the respiratory indexes and dead space volume. A femoral vein was cannulated, so that concentrations of the chemical in the blood and breath could be measured concurrently. Data from rats dosed orally and by inhalation with 1,1,1-trichloroethane are presented to illustrate the applicability of the method in kinetics studies of volatile chemicals.

Pulmonary excretion of H2 in calves with Cryptosporidium-induced malabsorption

Pulmonary hydrogen gas (H2) concentrations were used to assess the malabsorption of dietary nutrients in preruminating calves inoculated with Cryptosporidium sp. Normal values were established in five control calves and seven calves (principals) were inoculated with 1.0 x 10(8) Cryptosporidium sp. oocysts. Hydrogen concentrations and wet fecal weights were measured at three stages: before Cryptosporidium sp. inoculation (stage 1), three days after the onset of diarrhea (stage 2), and after the resolution of diarrhea (stage 3). Mean end-breath and total-breath H2 concentrations in the principal calves were higher (P less than 0.025 and P less than 0.05) for stage 2, when compared to control values. Both end-breath and total-breath H2 concentrations were increased (P less than 0.001 and P less than 0.025, respectively) in the principal calves during stage 2 when compared to values obtained for stages 1 and 3. Concurrently, Cryptosporidium sp. infection was associated with increased (P = 0.06) fecal output during stage 2, only. The increased H2 concentrations and cumulative fecal output show that Cryptosporidium sp. caused malabsorption of fermentable nutrients.

Applying the indicator amino acid oxidation technique in the domestic cat: results of a pilot study and development of a non-steady state prediction model

The aim of this study was to evaluate whether the indicator amino acid oxidation (IAAO) method could be applied in the domestic cat. Six adult male cats were used in a replicated 3 × 3 Latin square design. Three semi-synthetic diets were developed: a methionine (Met) and total sulfur AA (TSAA) deficient diet (T-BASAL; 0.24% Met+Cys - DM basis) and two Met and TSAA-sufficient diets in which either dl-Met (T-DLM) or 2-hydroxy-4-(methylthio)-butanoic acid (T-MHA) were supplemented, respectively, on an equimolar basis to meet the TSAA requirement (0.34%). After a 2-d diet adaptation, IAAO studies were performed. Cats were offered 13 small meals. The sixth meal contained a priming dose (4.8 mg/kg-BW) of l-[1-13C]-Phe and the remaining meals a constant dose (1.04 mg/kg-BW). Breath samples were collected every 25 min to measure 13CO2 enrichment. The following morning, fasted blood samples were collected. Cats returned to the T-BASAL top dressed with a dl-Met solution for 4 d prior to being fed a new dietary treatment. Isotopic steady state was evaluated through visual inspection. Data were analyzed using PROC GLIMMIX procedure in SAS 9.4. While 13CO2 enrichment was successfully captured in breath samples, cats failed to reach 13CO2 steady state. Thus, a non-steady state isotope model was developed and coded in ACSLX (V3.1.4.2) individually for each cat on each study day to predict 13CO2 enrichment, and then, calculate oxidation of l-[1-13C]-Phe (F13CO2). A higher predicted F13CO2 was observed for cats fed T-BASAL compared to the others (P < 0.05), while no differences were observed between T-DLM and T-MHA (P > 0.05). Cats fed T-DLM tended to have higher plasma Met concentrations compared to those fed T-BASAL with cats fed T-MHA intermediate (P = 0.0867). Plasma homocysteine concentrations were higher in cats fed T-BASAL compared to the others (P < 0.05), while threonine concentrations tended to be higher in cats fed T-BASAL compared to those fed T-MHA (P = 0.0750). In conclusion, short-term provision of a semi-synthetic diet deficient in Met may elicit a metabolic response aiming to conserve Met. The successful quantification of 13CO2 enrichment in breath and the higher predicted F13CO2 in cats fed a Met deficient diet suggest that the IAAO technique may be used in cats. Adaptations in the isotope protocol should be made to achieve 13CO2 steady state in breath and avoid mathematical modeling to predict F13CO2.

An easily assembled and inexpensive apparatus for continuous monitoring of expired carbon dioxide concentrations in artificially ventilated animals

An inexpensive and simple apparatus for monitoring expired carbon dioxide concentrations in artificially ventilated animal preparations is described. The system may be rapidly and easily constructed using a standard recording pH electrometer and a commercially available Pco2 electrode. This assembly has been proven to be an effective and sensitive means of monitoring CO2 levels, detecting changes in this gas within one-half percentage.

Usability of volatile organic compounds from exhaled breath compared with those from ruminal fluid, serum, urine, and milk to identify diet-specific metabolite profiles in lactating dairy cows

To investigate dietary influences on the volatilome, the volatile subcategory of the metabolome, we performed a comparative untargeted volatilome analysis of exhaled breath, ruminal fluid, serum, urine, and milk from lactating Holstein cows fed different diets. Thirty-two cows (83.3 ± 31.40 DIM, 30.6 ± 5.03 kg of milk/d) were assigned to 4 diets. The experiment lasted 16 wk. Throughout the experiment, half of the animals were fed a hay-based diet (HD; n = 16), and the other half were fed a silage-based diet (SIL; n = 16). In experimental wk 5 to 12, half of the animals in each group received the control concentrate (CON), and the other half was fed with the CON supplemented with a blend of essential oils (EXP). We hypothesized that the basal diet and the essential oils influence the volatile organic compound (VOC) profiles of the cows through potential changes in ruminal fermentation, digestion, and metabolism (hypothesis 1). Furthermore, we hypothesized that the potential effects of essential oils would have a delayed onset and a carryover effect (hypothesis 2). Every 4 experimental weeks (i.e., in wk 4, wk 8, wk 12, and wk 16), samples of exhaled breath, ruminal fluid, serum, urine, milk, and feed were collected for dynamic headspace extraction and gas chromatographic analysis of VOC in their gaseous phase. Milk yield, milk composition, BW, and feed intake were recorded regularly. Linear mixed models and multivariate and univariate data analyses were performed. The total DMI and basal diet intake was similar between cows fed HD and SIL diets. However, SIL cows consumed less of the concentrate, NDF, and water-soluble carbohydrates and more starch than HD cows. The SIL cows had a higher milk production than the HD cows. No effect was found regarding the concentrate type on feed intake or milk production. Irrespective of diet, 2,957 VOC were detected in the gaseous phase of serum; 2,771 in exhaled breath; 1,016 in urine; 1,001 in milk; and 921 in ruminal fluid. Across the experimental wk 4, 8, 12, and 16, the basal diet altered the VOC profiles of ruminal fluid, urine, and exhaled breath but not those of serum and milk. The concentrate type affected only the VOC profiles of the exhaled breath. Most diet-influenced VOC in the affected biological matrices were identified as dietary components. The experimental week influenced the VOC profiles of all matrices, especially those of exhaled breath. The VOC profile of exhaled breath strongly correlated with that of urine, followed by that of ruminal fluid, milk, and serum. This study provides the first description of diet- and time-specific VOC profiles from the biological matrices of dairy cows. The identified discriminatory VOC seem suitable as markers to discriminate between HD and SIL cows. Exhaled breath may be a promising, sensitive, and less invasive tool to follow diet- and time-related metabolic changes.

Pathway mapping of exhaled volatile organic compounds associated with blood and ruminal fluid metabolites to describe the nutritional and metabolic status of lactating dairy cows

Exhaled breath offers an interesting matrix for low invasive sampling of potentially relevant information about the organism's metabolism in the form of volatile organic compounds (VOC). The VOC can be exhaled by the ructus or pass the blood-lung barrier for expiration through the lungs. In this work, we consider exhaled breath as a mixture of VOC derived from the lungs and from the upper gastrointestinal tract. However, the informative value of exhaled breath in ruminants remains largely unstudied. The aim of this study was to identify exhaled VOC that could be used to assess the nutritional and metabolic status of dairy cows. To do so, we performed untargeted analysis of exhaled VOC from dairy cows, investigated their correlations with commonly analyzed blood and ruminal fluid metabolites and the calculated energy balance (EB), and explored the underlying pathways of correlated exhaled VOC. This was done as part of a feeding experiment in which 32 lactating Holstein dairy cows were assigned to 2 basal diets for 12 wk. Half of the cows were fed a hay-based diet, and the other half were fed a silage-based diet. During experimental wk 1 through 8, half of the cows in each basal diet group were supplemented with a control concentrate, and the other half received an experimental concentrate containing essential oils. During experimental wk 9 through 12, all cows received the control concentrate. Exhaled breath, blood, and ruminal fluid samples were collected every 4 experimental weeks (wk 4, 8, and 12) on 3 consecutive sampling days. Exhaled breath was analyzed for VOC, ruminal fluid for VFA and ammonia, and serum samples for albumin, total protein, urea, glucose, cholesterol, BHB, and nonesterified fatty acid (NEFA) concentrations. Pearson correlations were calculated to assess the associations between exhaled VOC and concentrations of blood and ruminal fluid metabolites and the calculated EB. Fifteen correlations were found between exhaled VOC (tetradecanal and γ-hydroxybutyrate [GHB], 3-penten-2-one, 4-hydroxy-4-methylpentan-2-one, 2-ethylhexanal, 2-ethylhexan-1-ol, p-cymene) and ruminal fluid (acetate, butyrate, valerate, and ammonia) and blood metabolite concentrations (BHB, NEFA, glucose, urea, and cholesterol) across the cow groups. The underlying pathways of 3-penten-2-one, GHB, and tetradecanal were mainly related to fat and protein catabolism and therefore to the actual animal metabolism. The correlations with the other 4 exhaled VOC, 4-hydroxy-4-methylpentan-2-one, p-cymene, 2-ethyl-hexan-1-ol, and 2-ethylhexanal, were diet- or time-related, specifically due to differences in feed ingredients. The results demonstrate the associations of single exhaled VOC with the nutritional and metabolic status of healthy dairy cows. Their potential as new biomarkers should be further investigated in cows in various nutritional and metabolic states.

The effect of feeding order of forage and oats on metabolic and digestive responses related to gastric emptying in horses

Feeding order of forage and concentrate might affect gastric emptying and subsequently digestion in horses. The objective of this study was to measure gastric emptying in combination with metabolic and digestive responses in the plasma and cecum, respectively, when changing the feeding order of oats (O) and hay (H) (oats first, then hay: O-H vs. hay first, then oats: H-O). Four cecum cannulated horses were used in a 2 × 2 crossover design, with two 12-d periods consisting of 10 d of diet adaptation and 2 d of data collection. Hay was fed at 0600, 1400, and 2000 hours, while oats were fed in the morning either 15 min before or 1 h after feeding hay. On days of data collection, baseline samples were collected before feeding 1.4 kg dry matter (DM) hay and 474 g DM oats (0.4 g starch/kg body weight), and data were collected until 8 h after feeding. Gastric emptying of oats was estimated using the 13C acetic acid breath test, where breath samples were analyzed for a 12C:13C ratio after administration of 13C acetic acid mixed with oats. Gastric emptying coefficient (GEC), time where half of the total cumulative recovery of 13C was excreted (t1/2), and time where the maximal amount of 13C was excreted (Tmax) were calculated. Samples of blood and cecal fluid were collected at hourly intervals. Blood plasma was analyzed for glucose and insulin, and baseline concentrations, peak concentrations, time of peaks, and area under the curves were calculated. A pH probe was placed in the cecum measuring pH every minute to find minimum pH and time to reach minimum pH. Hourly cecal samples were analyzed for pH and short-chained fatty acid (SCFA) concentrations. Results from the 13C acetic acid breath test indicated that feeding order affected gastric emptying, as Tmax was longer (P = 0.004) when feeding H-O (2.18 h) than O-H (1.09 h), but there was no effect on the GEC and T1/2. No effect of feeding order was found for plasma glucose and insulin measures. Feeding order had no effect on minimum pH, but the time to reach minimum pH increased (P = 0.014) from 170 min for O-H to 280 min for H-O, and average pH was lower in the intervals 0-170 min (P = 0.006) and 170-280 min (P = 0.006) for O-H than H-O. In general, the time of sampling had a larger effect on SCFA concentrations than feeding order. In conclusion, this study indicates that feeding order affected gastric emptying, and the digestive and metabolic responses were more clearly reflected in cecum pH than in plasma glucose and insulin.