Output In Sheep Research Articles

Purified and enriched lignin as a marker to estimate faecal output of sheep fed temperate and tropical grasses

A series of trials were conducted in different experimental and feeding conditions to evaluate a purified and enriched lignin extracted from Eucalyptus grandis (LIPE®) as a marker to estimate faecal output in sheep fed temperate and tropical grasses. Two indoor trials were conducted in metabolism cages: the first one (Trial I) was conducted with sheep fed Italian ryegrass (Lolium multiflorum Lam.) pastures, which was evaluated in two different periods [Period I (n = 14), and Period II (n = 15)], and the second one (Trial II) was performed with sheep fed pearl millet [Pennisetum americanum (L.) Leeke] pastures (n = 16). Grazing trials were performed with sheep grazing Italian ryegrass [Trial III (n = 62)] and pearl millet [Trial IV (n = 34)]. According to the manufacturer's statements, sheep were dosed once a day with capsules containing 250 mg of LIPE® for a period of seven days, beginning two days before total faecal collections started and finishing on the last faecal collection day. To measure the observed daily faecal output, sheep were harnessed with faecal bags that were emptied once a day at 0800 h for five days. Faecal subsamples from indoor and grazing trials were taken to determine the LIPE® content by infrared spectroscopy. Regression analyses performed between estimated and observed faecal output (g DM/kg LW/day) by sheep were not significant (p > 0.05) in three of the four evaluated trials. Faecal LIPE® recovery from the total data of the four trials showed a statistical difference when compared to the reference value (100%). In conclusion, our results show that the LIPE® marker presents low accuracy to estimate the daily faecal output of sheep fed temperate (Italian ryegrass) and tropical (pearl millet) grasses.

34. Using urinary creatinine to predict daily urine output in sheep fed fresh forages

34. Using urinary creatinine to predict daily urine output in sheep fed fresh forages

Immunopathological Response, Histological Changes, Parasitic Burden, and Egg Output in Sheep Naturally Infected by Dicrocoelium dendriticum.

Simple SummaryDicrocoelium dendriticum, commonly known as the lancet liver fluke, is a liver parasite that affects ruminants and occasionally other species, including humans. The aim of this study was to investigate the histological modification and the phenotype of inflammatory cells in the livers of sheep naturally infected with D.dendriticum and the correlation of these variables with the parasitic burden, egg output, and gross appearance of the liver. We studied twenty-four sheep selected on the basis of positive D. dendriticum fecal egg counts. Gross and histological modifications of the liver and the number of adult D. dendriticum worms were examined. Macroscopically, the livers were swollen with thickened bile ducts, cholangitis, and fibrosis. Histologically, we observed leucocyte infiltration, bile duct hyperplasia, and fibrosis. Lesions were present in different degrees of severity and were scored. A significant positive association was observed between the number of adult worms recovered from the liver, egg per gram, macroscopic lesions, fibrosis, and bile duct hyperplasia. A significant negative association was observed among these variables and the degree of leukocyte infiltration. The immunohistochemical examination showed a CD3+ predominant cell population in all assessed animals. These findings allow us to better understand the complex mechanism of the host–parasite interaction, in relation to the egg output and parasitic burden in dicrocoeliosis.The aim of this study was to investigate the correlation between infection by Dicrocoelium dendriticum (class Trematoda) and the animal host response in terms of macroscopic lesions, the immunopathological response, and histological changes in the livers of naturally infected sheep. Twenty-four sheep were selected on the basis of positive D. dendriticum fecal egg counts (FECs). Gross and histological injuries were scored. A positive significant association was observed between the number of adult worms recovered from the liver, FEC, macroscopic lesions, fibrosis, and bile duct hyperplasia. A significant negative association was observed among these variables and the degree of leukocyte infiltration. In addition, immunophenotyping of the inflammatory cells was carried out using primary antibodies against T cell epitopes (CD3+, CD4+, and CD8+), B cell epitopes (CD79α), and the ionized calcium-binding adapter molecule 1 (IBA-1) antigen. Independently of the severity of the D. dendriticum infection, the predominant cell population was CD3-positive and associated with lesser numbers of CD79α- and Iba-I-positive cells. An increase in Iba-1-positive cells was observed in the livers of animals with a high worm burden. Our results provide a reference basis to better understand the local immune response in sheep naturally infected by D. dendriticum in relation to the FEC and parasitic burden.

Titanium dioxide (TiO2) as a marker to estimate fecal output in sheep

ABSTRACT: Titanium dioxide (TiO2) is an external marker used to estimate fecal output based on forage intake of grazing ruminants; however, its use as marker for grazing sheep still needs attention. In the present study the TiO2 role to estimate fecal output of sheep grazing annual ryegrass was tested. Two essays were conducted in sequence using the same forage and animals. Six lacaune lambs were housed in metabolic cages. Lambs were administered 1 g TiO2 in a single (at 8:30 am, essay 1), or in two daily doses (at 8:30 am and 4:30 pm, essay 2). In both essays the TiO2 administration was followed by a 7-day period to stabilize the fecal excretion of the marker and then by a 5-day period for total collection of feces. Observed and TiO2-based estimated fecal outputs were compared, with or without correction for TiO2 fecal recovery rate (kTiO2). The kTiO2 was around 1.0 and the estimated fecal outputs were similar to the observed ones (p>0.05), regardless the number of daily doses. These results suggested that TiO2, administered in single or two daily doses, can be used as an external marker in grazing sheep.

Polyethylene glycol determined by near-infrared reflectance spectroscopy to estimate faecal output in sheep fed fresh permanent grassland forage

This study evaluated the feasibility of using different doses of polyethylene glycol (PEG) as an external marker of faecal output in sheep fed permanent grasslands fodder and compared two near-infrared reflectance spectroscopy (NIRS) calibration strategies for determining faecal PEG content. Three levels of PEG (0.25%, 0.75% and 1.5% of total daily intake) were administered to eight wethers, with each level dosed twice daily. Animals were fed forage obtained from two permanent grasslands cut at two dates during the first cycle of growth. Polyethylene glycol recovery rate was higher (P<0.001) at the highest dose (0.78) and decreased as dose level decreased (0.61 and 0.30 for PEG levels of 0.75% and 0.25% of total daily intake, respectively). NIRS calibration equations established on PEG data dosed directly on the faecal samples (0.61) gave higher (P<0.001) PEG recovery rates than NIRS calibration equations performed on mixtures of faeces with different PEG concentrations (0.49). Finally, faecal output estimates were more accurate (P<0.001) when faeces were sampled at 8:00 (0.61) than at 16:00 (0.51). The highest PEG recovery rate (0.88) was achieved using the highest dose on morning samples when PEG content was estimated by NIRS using turbidimetric results as reference values. We conclude that the usefulness of PEG as an external marker for estimating faecal output on permanent grasslands is limited at PEG doses lower than 1.5% of intake.

Recovery of COCs from ovaries with high follicle numbers enhances in vitro embryo yield in sheep

The aim of the present study was to investigate the correlation between the number of ovarian follicles and in vitro embryo development and quality in sheep. Sarda ewe ovaries were classified according to the number of follicles: ≤4 (Low), 5–7 (Intermediate), and ≥8 (High). IVM, IVF and IVC were performed under standard conditions. Cleavage rate and blastocyst development were assessed 48 h after fertilization and on Days 6, 7 and 8 of culture, respectively. Expanded blastocysts were vitrified; blastocoel re-expansion and hatching rates were assessed at 8, 16 and 72 h post-thawing and hatched blastocysts were analyzed with the TUNEL assay. In a subset of thawed blastocysts the incorporation of amino acids was evaluated. The proportion of ovaries varied significantly among the three groups (ANOVA F = 12.20, P = 0), and more ovaries (59%) were assigned to the Low group than to the Intermediate (28%; ANOVA F = 8.19, P = 0.009) and High group (13%; ANOVA F = 18.63, P = 0), (High vs. Intermediate F = 6.31, P = 0.020). The three groups statistically differed in the proportion of total blastocysts ( χ 2 2 = 22.616, P = 0.00), of blastocysts produced on Days 6 ( χ 2 2 = 6.829, P = 0.033) and 7 ( χ 2 2 = 6.810, P = 0.033), while no difference was found in the proportion of blastocysts obtained on Day 8 ( χ 2 2 = 3.874, P = 0.144) of culture after fertilization. A higher proportion of total blastocysts was obtained from the High (44%) compared with the other two groups (Low: 28%, χ 2 2 = 22.629, P = 0; Intermediate: 33%, χ 2 2 = 7.266, P = 0.007), while the Low and Intermediate groups did not statistically differ either in the total blastocyst output ( χ 2 2 = 3.384, P = 0.066), nor in the number of blastocysts produced on Days 6 (Low: 7%, Intermediate: 9%; χ 2 2 = 0.874, P = 0.35), 7 (Low: 14%, Intermediate: 16%, χ 2 2 = 1.256, P = 0.26) and 8 (Low: 6%, Intermediate: 7% χ 2 2 = 0.554, P = 0.45) of culture. The High group produced a significantly higher percentage of embryos on Days 6 (High: 13%, Low: 7%; χ 2 2 = 6.840, P = 0.009) and 7 (High: 21%, Low: 14%; χ 2 2 = 6.806, P = 0.009) of culture post-insemination than the Low group. The three categories did not differ in the blastocoel re-expansion ( χ 2 2 = 0.095, P = 0.95) and hatching rates ( χ 2 2 = 0.754, P = 0.68) after 72 h post-warming, in the total number of cells per blastocyst (ANOVA F = 1.12, P = 0.337) and in the ( F = 0.46, P = 0.639) incorporation of amino acids. The number of TUNEL-positive cells per embryo was higher (ANOVA F = 4.32, P = 0.022) in the Low group compared to the other groups. In conclusion, high ovarian follicle number enhances in vitro embryo output in sheep, but has no effect on blastocyst quality.

Induction of the presence of corpus luteum during superovulatory treatments enhances in vivo and in vitro blastocysts output in sheep

This report offers the results of two experiments developed to test possible benefitial effects of the presence of corpus luteum (CL) on in vivo and in vitro sheep embryo production; using two different breeds treated with two different protocols by two different teams at two different centres. In the first trial, estrus was synchronized in 11 ewes with two doses of cloprostenol, 10 days apart. On day 1 after estimated ovulation, sheep were treated with progestagen sponges and superovulated with eight decreasing doses (26.4 units NIH-FSH-S1 × 3, 22.0 units × 2, and 17.6 units × 3) of ovine FSH injected twice daily. Ovulation rate and number of embryos obtained in vivo were compared to those from 12 control ewes without cloprostenol treatment. Presence of a CL improves the number of transferable embryos (7.4 ± 0.6 versus 4.1 ± 0.6 in control ewes, P < 0.05). The second trial investigated the effects of the presence of CL on embryos produced in vitro from six ewes bearing CL and six ewes without CL at start a superovulatory treatment consisting of 96 units of ovine FSH administered in four equal doses given every 12 h. There were not detected effects of the CL on the number and size of follicles or in the number, morphology and ability to resume meiosis of their oocytes. However, oocytes from ewes with CL showed higher rates of fertilization (73.5 versus 45.5%, P < 0.005), higher development to blastocyst (35.8 versus 19.3%, P < 0.01) and higher hatching rates after vitrification (80.0 versus 25.0%, P < 0.05).

219EFFECTS OF GROWTH HORMONE AND GNRH ANTAGONISTS ON FOLLICULAR AND OOCYTE DEVELOPMENT IN SHEEP

Embryo output in sheep is increased when superovulatory FSH treatments are started in the presence of a high number of small follicles (2–3mm in size) and in absence of large follicles (&amp;gt;6mm, Gonzalez-Bulnes et al., 2002. Theriogenology, 57, 1263–1272). Administration of GnRH antagonists (GnRHa) suppresses large follicles (Cognie et al., 2003. Theriogenology, 59, 171–188), whereas the use of growth hormone (GH) would increase the number of small follicles (Campbell et al., 1995. J Reprod Fertil Suppl, 49, 335–350). Our aim was to evaluate the usefulness of pre-treatments with GH or GH plus GnRH antagonists for sheep embryo production. First, we studied the effects on follicular population by serial ultrasonographies. Thereafter, we determined whether such treatments can affect oocyte developmental competence. In a first trial, a total of 18 Manchega ewes were treated with intravaginal FGA sponges (Chronogest®, Intervet Int., H) during breeding season (beginning of April). Six animals received daily i.m. doses of 15mg of ovine GH (Tuenre, GA) for 6 days, while six females received GH plus two s.c. doses of 1.5mg of GnRHa (Antarelix™, Zentaris, G) on Days 0 and 3 of GH treatment, and six ewes acted as controls receiving saline. Number of follicles &amp;gt;2mm, determined by daily transrectal ultrasonography, increased to reach significant differences on Day 4 in sheep treated with GH/GnRHa (22.7±0.8 v. 16.7±0.5, P&amp;lt;0.001) and on Day 5 in ewes injected with GH (20.3±0.4 v. 17.0±0.6, P&amp;lt;0.05). The second trial involved 18 Manchega ewes treated with progestagen sponges on Day 0 and distributed in three groups at the beginning of breeding season (end of July). In the first group (n=7), sheep were treated with two doses of GnRHa on Days 0 and 3 after sponge insertion and with three doses of 15mg of GH on Days 3, 4, and 5. Thereafter, ewes from this group and from a second experimental group (n=7) were treated with 3 doses of 1.5mL of FSH (Ovagen™, ICP, NZ) every 12h, starting on the afternoon of Day 5. A third group of sheep (n=4) did not receive GH/GnRHa or FSH, acting as controls. On Day 7, follicles were aspirated and the cumulus-oocyte complexes (COC) were cultured for 24h at 38.5°C, 5% CO2, in TCM-199 supplemented with ovine FSH (Ovagen), LH, FCS, 17-βoestradiol, cysteamine, and sodium pyruvate (Sigma Chemical Co., MO, USA). Nuclear maturation was measured by Hoechst 33342 fluorescence. Mean number of COC was higher in GH/GnRHa+FSH group (8.7±0.9 v. 6.8±1.3 in FSH group, NS and 4.5±0.8 in control, P&amp;lt;0.05) due to higher number of follicles with similar recovery rates (45.0±4.5, 40.3±1.4, and 39.1±7.1%, respectively). There were no significant differences on the ability of COC to resume meiosis, although this was higher in FSH group (63.1±9.5% for GH/GnRHa+FSH, 79.5±6.3% for FSH and 60.0±8.8% for control group), which can indicate the necessity of a higher FSH supply to induce final development in follicles/oocytes from ewes treated with GH and GnRHa. In conclusion, the use of GH and GnRHa would help to increase the number of gonadotrophin-responsive follicles prior to gonadotrophin injections;; also, adjustment of FSH treatments improved embryo yields in superovulatory protocols.

Epinephrine causes a reduction in lymph node cell output in sheep

The lymphatic system has a critical role in the return of fluids, proteins, and cells to the circulatory system. However, the effects of stress, including exercise, on this system have not been adequately studied. We investigated the effect of a physiological dose (1 mg) of epinephrine (Epi) on lymph flow, cell concentration, and lymphocyte subsets in efferent subcutaneous lymph in sheep. Blood leukocyte numbers, differential, lymphocyte subsets, and blood and lymph pools of lymphocytes were determined simultaneously. A significant acute increase in lymph flow was followed by a post-injection decrease in flow and cellular output. No changes in lymphocyte subsets or pools of lymphocytes were seen in either blood or lymph. The timing of elevated plasma and lymph concentrations of Epi and norepinephrine (NE) corresponded with the increased lymph flow. In conclusion, Epi injection caused no change in lymphocyte subset distribution, leukocyte concentration, or pools of lymphocytes. A decrease in lymph flow and cellularity was documented post-injection, indicating that lymphatic tissue has no role in the leukocytosis seen after Epi injection. Lymphocyte retention by lymph nodes, however, may contribute to post-injection lymphopenia.

Nitric Oxide and Septic Vascular Dysfunction

Nitric Oxide and Septic Vascular Dysfunction

Comparison of diet and faecal collection methods for assessment of seasonal variation in dry matter intake by sheep maintained on a Cenchrus ciliaris pasture

Four diet collection methods: clipping(C), mouth grab (MG), plucking (P) and oesophageal extrusa (OE) and two faecal output estimation methods: faecal bag (FB) and Cr 2O 3 marker (I) were compared to assess seasonal changes in nutrient composition of diet and dry matter intake of sheep on Cenchrus ciliaris pasture. Crude protein (CP) and lignin contents of OE were higher than C, MG and P during all the seasons. Fiber fractions were lowest in MG, highest in C and intermediate in OE and P methods. Pooled CP contents of diet samples declined ( P < 0.01) from 12.7% in monsoon to 9.3 and 7.9% in winter and summer while ADF, cellulose and lignin increased from monsoon to summer. Clipped samples had lower NDF, ADF, cellulose, hemicellulose and gross energy digestibility compared to P, MG and OE methods in all the seasons. Nutrient digestibility declined from monsoon to winter and summer in all the diet samples collected by the four techniques. CP digestibility showed marked depression from 63.1% in monsoon to 44.1 and 14.4% in winter and summer. Faecal collection bag and Cr 2O 3 marker methods estimated similar faecal outputs in all the seasons. The OE method estimated a lower DM intake of the animals (mean 960 g/day) compared to C, P and MG methods (mean 1381 g/day). Animals consumed more dry matter during winter (mean 1706 g/day) than during monsoon and summer (mean 1030 g/day) seasons. It is concluded that diet sampling method and season had an influence on the estimated diet composition and DMI of sheep on semi-arid pastures. Both methods of faecal collection, however, estimated similar daily faecal output in sheep.

Effects of bacterial inoculation of unwilted and wilted grass silages. 1. Rumen microbial activity, silage nutrient degradability and digestibility

A set of four silages, comprising unwilted and wilted silages, both with and without bacterial inoculation, was prepared from perennial ryegrass swards on each of eight harvesting occasions during the 1994 growing season. The four silages, within a single harvest, were offered as the total diet at the maintenance level of feeding to 16 wether sheep in an 8-period change-over study with experimental periods of 3 weeks duration, in order to determine whole tract digestibility and urinary excretion of purine derivatives (PD). Silage dry matter (DM) and nitrogen (N) degradabilities were also examined in the rumen of four rumen-fistulated steers offered a medium quality silage and a concentrate supplement at a ratio of 60[ratio ]40 (silage[ratio ]concentrate) on a DM basis. The data presented are the mean results obtained across the eight harvests.There were no significant effects of inoculation on silage pH and ammonia-N/total-N across the unwilted and wilted materials. Inoculation of either the unwilted or wilted silages had no significant effect on microbial activity in the rumen of sheep, as indicated from excretion of urinary PD, or on silage DM or N degradability assessed with rumen-fistulated steers. However, inoculation significantly increased the digestibility of organic matter (1·7%, P&lt;0·01), N (4·6%, P&lt;0·001), energy (2·3%, P&lt;0·01), neutral detergent fibre (1·5%, P&lt;0·05) and acid detergent fibre (2·8%, P&lt;0·001) in the silage. These increases in digestibility following inoculation, in general derived equally from both the unwilted and wilted silages. The results indicate that the increase in silage nutrient digestibility following inoculation probably reflects a more extensive digestion in the abomasum and intestine, rather than in the rumen.Wilting of grass prior to ensiling resulted in silages with significantly lower pH (5·4%, P&lt;0·05) and ammonia-N/total-N (42·7%, P&lt;0·001) across the untreated and inoculant-treated materials. Wilting also significantly increased (P&lt;0·05) urinary PD-N output of sheep by 6·9% and silage DM degradability by steers by 1·6–2·4% across the untreated and inoculant-treated silages. However, there were no significant effects of wilting on silage N degradability and silage nutrient digestibility.

Effects of insulin-like growth factor-1 on luteinizing hormone secretion in sheep.

Circulating insulin-like growth factor-1 (IGF-1) may be involved in nutritional modulation of reproductive status. Acute effects of IGF-1 on luteinizing hormone (LH) secretion were studied in two experiments, each using eight castrate male sheep surgically prepared with an elevated carotid artery, four with (E+) and four without (E-) subcutaneous oestradiol implants. Blood samples were taken every 12 min for 8 h at weekly intervals, with IGF-1 given at 4 h. In Experiment 1, sheep were fed to maintain live weight (maintenance) and IGF-1 doses tested were 25, 50, 100 and 150 micrograms kg-1 given via the carotid (i.c.). Plasma LH concentrations were 6.2 +/- 0.35 (E-) and 4.2 +/- 0.49 (E+) ng ml-1 pre-IGF-1, were increased after 25 micrograms kg-1 IGF-1 (E-, 15%; E+, 11%) but were either unaltered (E-) or decreased (E+, -16%) after 150 micrograms kg-1; thus, mean LH response was negatively related to IGF-1 dose (E-, b = -0.007, P < 0.01; E+, b = -0.011, P < 0.05). LH pulse frequencies (p.f.) were 4.6 +/- 0.42 (E-) and 3.9 +/- 0.35 (E+) pulses per 4 h pre-IGF-1, were unaltered after 25 micrograms kg-1 IGF-1, but were decreased after 150 micrograms kg-1 (E-, -33%; E+, -51%); thus, p.f. was also negatively related to IGF-1 dose (E-, b = -0.016, P < 0.01; E+, b = -0.019, P > 0.05). LH pulse amplitude and baseline were not significantly altered by IGF-1. Plasma glucose concentrations decreased after 100 and 150 micrograms kg-1 IGF-1 from 3.40 to 2.50 and 2.34 mmol l-1, respectively (SED 0.314, P < 0.001), but were not significantly altered after lower doses. Thus, hypoglycaemia caused LH inhibition after higher doses of IGF-1, which counteracted (E-) or overcame (E+) the stimulatory effects on LH seen after lower doses. In Experiment 2, sheep were fed 50% maintenance; saline vehicle i.c., then IGF-1 doses 25 and 50 micrograms kg-1 given i.c. or i.v. were tested. In E- and E+ sheep, respectively, mean LH pre-IGF-1 was 8.7 +/- 0.97 and 1.9 +/- 0.16 ng ml-1, p.f. was 3.8 +/- 0.44 and 0.8 +/- 0.44 pulses per 4 h, and amplitude was 3.6 +/- 0.49 and 0.4 +/- 0.08 ng ml-1. Saline vehicle had no effect on LH. IGF-1 at both doses and by both administration routes in E- sheep increased mean LH (22-29%, P < 0.001), and in E+ sheep increased mean LH (12-36%, P < 0.001), p.f. (94-219%, P < 0.001) and amplitude (125-803%, P < 0.01). Thus, low doses of peripherally-administered IGF-1 stimulated LH output in sheep, consistent with its putative physiological role as a nutritional modulator of reproduction.

Beneficial hemodynamic and renal effects of adrenomedullin in an ovine model of heart failure.

Adrenomedullin is a recently discovered endogenous peptide with hypotensive and natriuretic actions in normal animals. Circulating and ventricular adrenomedullin are elevated in congestive heart failure, suggesting a possible role in the pathophysiology of this disease. No studies have previously examined the effects of adrenomedullin in heart failure. Eight sheep with pacing-induced heart failure received human adrenomedullin(1-52) at 10 and 100 ng x kg(-1) x min(-1) I.V. for 90 minutes each. Compared with vehicle control data, adrenomedullin increased plasma cAMP (high dose, P<.05) in association with dose-dependent falls in calculated peripheral resistance (13 mm Hg x L(-1) x min(-1), P<.001), mean arterial pressure (9 mm Hg, P<.001), and left atrial pressure (5 mm Hg, P<.001) and increases in cardiac output (0.5 L/min, P<.001). Adrenomedullin increased urine sodium (threefold, P<.05), creatinine (P<.05) and cAMP excretion (P<.01), creatinine clearance (P<.05), and renal production of cAMP (P<.05), whereas urine output was maintained during infusion and raised after infusion (P<.05). Adrenomedullin reduced plasma aldosterone levels (P<.05), whereas plasma atrial and brain natriuretic peptide concentrations were unchanged during infusion and rose after infusion (P<.01 and P<.05, respectively). Plasma catecholamine, cortisol, renin, calcium, and glucose concentrations were not significantly altered. Adrenomedullin reduced ventricular preload and afterload and improved cardiac output in sheep with congestive heart failure. Despite the clear fall in arterial pressure, adrenomedullin increased creatinine clearance and sodium excretion and maintained urine output. These results imply an important pathophysiological role for adrenomedullin in the regulation of pressure and volume in heart failure and raise the possibility of a new therapeutic approach to this disease.

Noninvasive measurements of cardiac output in sheep: an improved thermometry method

In 25 sheep and 5 goats, which were anesthetized, intubated and mechanically ventilated a sudden decrease in the inspired gas humidity was used to cool the lungs. The dynamics of the temperature of expired gas and its relationship to ventilation rate and cardiac output measured by thermodilution were investigated. In six animals minute ventilation was changed at a stable cardiac output and in 14 animals cardiac output was changed by infusion of saline or by bleeding at a constant ventilation. The difference between the blood temperature and the expired gas temperature at a steady state is proportional to minute ventilation and is inversely proportional to the cardiac output. The inverse time constant of the decay of temperature of the expired gas is proportional to the cardiac output and does not depend on ventilation. The lungs function as a natural humidifier of the respiratory gases with an inner heat source from the pulmonary circulation and an outer heat sink to the expired gas. A simple lumped heat capacity model of non-steady state heat exchange in the lungs was developed, which may be used as a basis for the non-invasive method for determining cardiac output. The coefficient of the lung thermal conductivity ( K T/( ρ W C pW)=0.156±0.056) was determined and applied to measure cardiac output in a separate group, designed as a prospective study. When calculations of cardiac output were done based on the lung mass, estimated from the body weight (12 g/kg), bias and precision compared with thermodilution were −0.27 l/min and 0.38 l/min, respectively in 15 animals. Measurements of blood flow by the air thermometry correlated very well with thermodilution cardiac output ( r=0.92). Thermometry of the expired gas is a promising approach to measure the cardiac output non-invasively.

Prediction of total fecal output in sheep fed silage using the Captec chrome controlled-release capsule

Six Finnish wethers (average weight, 52.3 kg) were used to determine the effectiveness of a controlled-release Cr 2O 3 bolus and the internal marker acid insoluble ash (AIA) for predicting fecal output. Wethers were fed grass silage for ad libitum intake. Each wether was dosed orally with one continuous-release Cr 2O 3 bolus (CRC) on the first day of the experiment. Chronology of the trial was as follows: Day 0 to 14, marker adaptation period; Day 15 to 21, total fecal collection; Day 22 to 23, fecal grab sampling every 4 h; Day 25 to 35, once-daily fecal grab sampling. Accuracy of marker-estimated fecal output derived from each method was compared within a marker with total fecal collection values using a paired t-test. Concentrations of AIA and Cr varied ( P < 0.10) between sampling times. Accuracy of fecal output estimates was better with the controlled-release Cr 2O 3 bolus ( r = 0.97; P = 0.03) than with AIA ( r = −0.08; P = 0.89). Grab samples taken once produced reliable ( r = 0.96; P = 0.02) estimates of fecal output of silage-fed wethers using the controlled-release Cr 2O 3 bolus. The controlled-release Cr 2O 3 bolus is a better marker than acid-insoluble ash for predicting fecal output of silage-fed wethers.

Evaluation of a transit-time system for the chronic measurement of blood flow in conscious sheep

The accuracy of transit-time ultrasonic flow probes for measurement of regional blood flow and cardiac output was evaluated after long-term implantation in sheep. Transit-time flow probes (3, 4, 6, and 20 mm) accurately measured flow in vitro. Recalibration in vivo demonstrated that this accuracy was maintained after 1-9 mo of implantation on the left circumflex coronary (3-mm probe), cranial mesenteric (6-mm probe), left renal (4-mm probe), and left external iliac (6-mm probe) arteries of sheep. The flow probes also showed good zero stability. However, a transit-time flow probe (20 mm) chronically implanted on the pulmonary trunk significantly underestimated cardiac output compared with thermodilution or timed collection of blood. Although this flow probe underestimated flow, the response was linear. Bilateral carotid occlusion caused mesenteric, renal, and iliac vasoconstrictions, confirming that innervation of these vascular beds was undamaged. For experimental purposes, regional blood flow was measured with transit-time flow probes and cardiac output was measured with electromagnetic flow probes calibrated against thermodilution. In summary, transit-time flow probes reliably and accurately measure regional blood flow over many months in adult sheep, but, to measure cardiac output in sheep, the probes must be calibrated in vivo against another reference technique.

The effect of salt and bentonite supplementation on feed and water intake, faecal characteristics and urine output in sheep

The effects of the addition of salt (sodium chloride) and sodium bentonite to hay-based pelleted rations on feed and water intake, digestibility, the output of urine and faeces, and faecal consistency were evaluated under conditions resembling those used for the shipment of live sheep. The addition of salt to the diet had no effect on dry matter intake but increased water intake relative to controls (P<0.01), with commensurate increases in urinary output of more than 1 litre/sheep/day. The diet with bentonite plus salt resulted in a higher dry matter intake than controls (P<0.01). The addition of bentonite increased the faecal dry matter percentage (P<0.05). The effects of the additives on faecal water evaporative loss and hardness were not significant. A large variation (52.1-62.6%) between sheep in dry matter digestibility of feeds was not affected by treatment and this requires further investigation. It is recommended that salt not be added to diets used for live sheep shipments.

Effect of air temperature and feed intake on live weight and water balance in sheep

Environmental conditions (Clark &amp; Quin, 1949; Daws &amp; Squires, 1974; Degen &amp; Young, 1980) and total feed intake (Clark &amp; Quin, 1949; Forbes, 1968; Degen &amp; Young, 1980) influence the water intake of sheep. In general, high temperatures increase the requirements for water needed for evaporative cooling and high feed intakes necessitate more water for excretion of waste products. This study was designed to measure water intake and estimate the partition of water output in sheep maintained at four air temperatures and offered four levels of a ration.

Pulmonary edema in dogs, especially the sequence of fluid accumulation in lungs.

Pulmonary edema in dogs, especially the sequence of fluid accumulation in lungs.