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Biomedical subjects

W H Hendriks

Publications and source records attributed to W H Hendriks.

16 recordsLinked to original sources
PubMed2004

Use of capillary (zone) electrophoresis for determining felinine and it's application to investigate the stability of felinine.

A rapid capillary electrophoresis method was established to quantify felinine (2-amino-7-hydroxy-5,5-dimethyl-4-thiaheptanoic acid) in cat urine and used to investigate felinine stability. Synthetic felinine was stable in the presence of oxygen while 11% of the natural felinine in urine disappeared after 4 days exposure to air. Both synthetic felinine and the natural felinine (in urine) were stable for up to 3 months when stored at -5 degrees C and 20 degrees C. Thirty percent of the synthetic felinine was lost after 5 hours at 100 degrees C while 95% of the natural felinine disappeared after only 2 hours at the same temperature. The recovery of felinine under certain conditions was greater than 100%. It is possible that acetyl-felinine may be present in the urine and that it is deacetylated during incubation. Overall synthetic felinine was found to be stable but the felinine in cat urine much less so. Other compounds present in the urine may contribute to the decomposition of felinine.

Animals↗
PubMed2004

Influence of phytase and xylanase, individually or in combination, on performance, apparent metabolisable energy, digestive tract measurements and gut morphology in broilers fed wheat-based diets containing adequate level of phosphorus.

1. The aim of the present study was to examine the influence of microbial phytase and xylanase, individually or in combination, on performance, apparent metabolisable energy, digesta viscosity, digestive tract measurements and gut morphology in broilers fed on wheat-soy diets containing adequate phosphorus (P). The wheat-soy basal diet was formulated to contain 4.5 g/kg non-phytate P and the experimental diets were formulated by supplementing the basal diet with xylanase (1000 xylanase units/kg diet), phytase (500 phytase units/kg diet) or a combination of phytase and xylanase. 2. Supplemental phytase improved the weight gains and feed efficiency by 17.5 and 2.9%, respectively. Corresponding improvements due to the addition of xylanase were 16.5 and 4.9%, respectively. The combination of phytase and xylanase caused no further improvements in broiler performance. 3. Individual additions of xylanase or phytase resulted in numerical improvements in apparent metabolisable energy (AME), but the differences were not significant. The combination of the two enzymes significantly increased AME. Addition of xylanase and the combination of the two enzymes reduced the viscosity of digesta in all sections of the intestine. Phytase supplementation reduced digesta viscosity in the duodenum and ileum, but not in the jejunum. 4. Enzyme supplementation lowered the relative weight and length of the small intestine. Additions of xylanase and phytase reduced the relative weight of the small intestine by 15.5 and 11.4%, respectively, while the corresponding reductions in the relative length of the small intestine were 16.5 and 14.1%, respectively. The combination of phytase and xylanase had no further effects on the relative weight and length of the small intestine compared with the xylanase group. 5. The addition of phytase increased villus height in the duodenum and decreased the number of goblet cells in the jejunum compared with those on the unsupplemented basal diet. Xylanase supplementation tended to increase goblet cell numbers in the duodenum and decreased crypt depth in thejejunum. The combination of phytase and xylanase increased villus height in the ileum and crypt depth in thejejunum and ileum. 6. In summary, the present results showed that the addition of a microbial phytase, produced by solid state fermentation and containing significant activities of beta-glucanase and xylanase, was as effective as xylanase in improving the performance of broiler chickens fed on wheat-based diets containing adequate levels of P. Improved performance with enzyme supplementation was generally associated with reduced digesta viscosity, increased AME, and reduced relative weight and length of small intestine.

6-Phytase↗
PubMed2004

Influence of method of whole wheat inclusion and xylanase supplementation on the performance, apparent metabolisable energy, digestive tract measurements and gut morphology of broilers.

1. The aim of the present study was to examine the influence of whole wheat inclusion and xylanase supplementation on the performance, apparent metabolisable energy (AME), digesta viscosity, and digestive tract measurements of broilers fed on wheat-based diets. The influence of the method of whole wheat inclusion (pre- or post-pelleting) was also compared. A 3 x 2 factorial arrangement of treatments was used with three diet forms (648 g/kg ground wheat [GW], GW replaced by 200 g/kg of whole wheat before [WW1] or after cold-pelleting [WW2]) and two xylanase levels (0 and 1000 XU/kg diet). 2. Birds given diets containing whole wheat had improved weight gains, feed efficiency and AME compared to those fed on diets containing ground wheat. The relative gizzard weight of birds fed WW2 diets was higher than in those fed GW and WW1 diets. Pre-pelleting inclusion of whole wheat had no effect on relative gizzard weight. Post-pelleting inclusion of whole wheat resulted in greater improvements in feed efficiency and AME than the pre-pelleting treatment. 3. Xylanase supplementation significantly improved weight gain, feed efficiency and AME, irrespective of the wheat form used. Viscosity of the digesta in the duodenum, jejunum and ileum were reduced by xylanase addition. Xylanase supplementation reduced the relative weight of the pancreas. 4. Neither xylanase supplementation nor whole wheat inclusion influenced the relative weight and length of the small intestine. 5. Xylanase supplementation increased ileal villus height. A significant interaction between diet form and xylanase was observed for ileal crypt depth. Xylanase supplementation had no effect on crypt depth in birds fed on diets containing GW, but increased the crypt depth in WW2 diets. No significant effects of diet form and xylanase supplementation were observed for the thickness of the tunica muscularis layer of gizzard or villus height, crypt depth, goblet cell numbers or epithelial thickness in the ileum. 6. Improved performance observed with post-pelleting inclusion of whole wheat was associated with increased size of the gizzard and improved AME. The gizzard development hypothesis, however, will not explain the improvements observed with pre-pelleting inclusion of whole wheat, suggesting the involvement of other factors.

Animal Nutritional Physiological Phenomena↗
PubMed2003

Effects of microbial phytase, produced by solid-state fermentation, on the performance and nutrient utilisation of broilers fed maize- and wheat-based diets.

1. The influence of a microbial phytase on the performance, toe ash contents and nutrient utilisation of male broilers fed diets based on maize and wheat was investigated. The experiment was conducted as 2 x 2 x 2 factorial arrangement of treatments. Within the factorial, two diet types (maize-soy or wheat-soy) containing two levels of non-phytate phosphorus (3.0 or 4.5 g/kg) were evaluated and each level of non-phytate phosphorus was supplemented with 0 or 500 PU phytase/kg diet. Each of the 8 dietary treatments were fed to 6 pens of 8 birds from d 1 to 21 post-hatching. 2. Main effects of diet type and phytase were observed for all parameters. Main effect of non-phytate phosphorus was significant only for feed/gain and toe ash contents. Phytase addition improved weight gains irrespective of diet type or non-phytate phosphorus level, but the magnitude of improvement in the phosphorus-deficient wheat-soy diet was greater, resulting in a diet type x non-phytate phosphorus interaction. Responses in toe ash contents were noted only in phosphorus-deficient diets, as indicated by a non-phytate phosphorus x phytase interaction. 3. Phytase addition improved apparent metabolisable energy values of wheat-based diets, but had little effect on the apparent metabolisable energy of maize-based diets as shown by a diet type x phytase interaction. The apparent metabolisable energy was not influenced by dietary non-phytate P. 4. Phytase improved ileal nitrogen digestibility in both diet types, but the responses to added phytase tended to be higher in wheat-based diets, as shown by a diet type x phytase interaction. 5. Increasing the dietary non-phytate phosphorus level reduced phosphorus digestibility and increased excreta phosphorus content. Addition of phytase improved phosphorus digestibility, but the increments were higher in low phosphorus diets resulting in a non-phytate phosphorus x phytase interaction. Phytase addition tended to lower the excreta phosphorus content, but the effects were greater in birds fed low phosphorus diets, as shown by a non-phytate phosphorus x phytase interaction.

6-Phytase↗
PubMed2002

Comparison of the endogenous ileal and faecal amino acid excretion in the dog (Canis familiaris) and the rat (Rattus rattus) determined under protein-free feeding and peptide alimentation.

The aim of the study was to determine and compare the endogenous ileal excretions of nitrogen and amino acids under protein-free and peptide alimentation by the dog and rat. Two diets were prepared, one that was devoid of protein and the other containing 23% enzyme hydrolysed casein. Chromic oxide was included in the diets as an indigestible marker. A total of 10 mixed breed dogs were fed hourly either a protein-free or enzymatically hydrolysed casein diet for a total of 10 days. A faecal sample was obtained from each dog on day 9 while digesta was obtained from the terminal 20 cm of the ileum directly after euthanasia on day 10. A total of 12 8-week-old Sprague-Dawley rats received the same diets as the dogs. A faecal sample from each rat was obtained on day 7 while ileal digesta samples were obtained on day 8. The endogenous ileal excretions of most amino acids were greater in the dogs and rats that received the enzymatically hydrolysed casein diet compared with those receiving the protein free diet. Whereas the pattern of endogenous amino acid excretion was similar in the rats and dogs, the dogs excreted a significantly greater amount of nitrogen (1.91 vs. 2.27 and 1.63 vs. 4.12 g/kg dry matter intake for the protein-free and peptide alimentation method, respectively) and all amino acids except for glycine, isoleucine and leucine. Endogenous ileal amino acid excretions are higher in dogs compared to omnivorous animals such as rats and pigs but similar to the carnivorous cat.

Amino Acids↗
PubMed2001

Importance of sulfate, cysteine and methionine as precursors to felinine synthesis by domestic cats (Felis catus).

There is conflicting evidence in the literature on the utilization of cysteine and methionine as precursors to the urinary sulfur-containing amino acid felinine in cats. Three entire domestic short-haired male cats, housed individually in metabolism cages, were injected intraperitoneally with either [35S]-sulfate, [35S]-cysteine, or [35S]-methionine. Daily urine samples were collected quantitatively for up to 9 days after injection. Each cat was injected once with each compound after observing an appropriate interval for [35S] to be depleted between injections. All the urine samples were analysed for felinine content and total radioactivity. Felinine was isolated from each urine sample and analysed for radioactivity. No radioactivity was found in felinine from cats injected with [35S]-sulfate. The mean (+/-S.E.M.) cumulative recovery of radioactivity in the urine of the [35S]-sulfate injected cats was 90.6+/-6.1% after 4 days. The mean (+/-S.E.M.) cumulative incorporation rate of radioactivity into felinine by the cats receiving the [35S]-cysteine and [35S]-methionine were 11.6+/-1.6 and 8.6+/-0.6%, respectively, after 9 days. The mean (+/-S.E.M.) cumulative recoveries of radioactivity in the urine were 58.1+/-3.7 and 36.0+/-8.0%, respectively. Cysteine and methionine, but not sulfate, are precursors to felinine, with cysteine being a more quantitatively important precursor compared to methionine.

Animals↗
PubMed2000

Milk intake of suckling kittens remains relatively constant from one to four weeks of age.

The daily milk intake of 14 domestic short-haired kittens (Felis catus) from five litters was estimated during wk 1-4 postpartum using the isotope dilution technique. Kittens received a single intraperitoneal injection of tritiated water, and blood samples were obtained from the jugular vein for radioactivity measurements at 2 and 96 h after injection. One kitten in each litter was used as a control to allow calculation of recycling of tritiated water. The mean (+/- SEM) biological half-life of tritiated water in the kittens increased from 2.4 +/- 0.1 d in wk 1 to 4.9 +/- 0.2 d in wk 4 postpartum. Recycling of tritiated water accounted for (mean +/- SEM) 5.9 +/- 0.8, 12.0 +/- 0.5, 7.7 +/- 1.3 and 10.0 +/- 1.3% of the kittens' daily water intake during postnatal wk 1-4, respectively. Daily milk intake of the kittens during wk 1-4 postpartum was 47.3 +/- 0.8, 47.4 +/- 1.5, 48.7 +/- 1.6 and 43.7 +/- 2.0 g, respectively. There was no effect of gender on milk intake. The daily metabolizable energy requirement of suckling kittens, estimated by multiple regression analysis, was 356 kJ/kg(0.75), whereas the metabolizable energy required per gram of gain was estimated to be 7. 8 kJ/d. The milk intake of suckling kittens remained relatively constant throughout the first 4 wk of lactation, and during this period, they seemed to have a lower energy requirement for maintenance.

Aging↗
PubMed1999

Heat processing changes the protein quality of canned cat foods as measured with a rat bioassay.

The purpose of this study was to determine the influence of increasing heat treatment on the protein quality of a canned cat food. A standard recipe cat food was canned and heat-treated for different times in a standard laboratory autoclave to obtain experimental diets containing different lethality values. Estimates of the lethality value of the different diets were calculated using the temperature-time relationship recorded with a data logger positioned at the center of the can. The experimental diets were analyzed for crude protein, amino acids, and reactive lysine (fluorodinitrobenzene and O-methylisourea) and were used in a rat bioassay for the determination of the true ileal digestibility of amino acids. The heat treatment of the cat food resulted in experimental diets with lethality values of 5.3, 8.6, 17.2, and 24.3 min. There was no decrease in the amino acid content of diet with increasing heat treatment. The reactive lysine content of the diets also showed no change with heat treatment. There were significant (P < .05) changes in the true ileal digestibility of all amino acids and amino acid nitrogen, and the digestibility of most amino acids decreased with increasing heat treatment.

Amino Acids↗
PubMed1998

Relationship between plasma testosterone and urinary felinine in the growing kitten.

Felinine, a unique amino acid the functions of which are not well understood, is found in large quantities in male cat urine. Our study ran for 13 calendar months and involved taking monthly samples of blood and urine from 10 male and 10 female kittens starting at 6 months of age and measuring urinary felinine and plasma testosterone concentrations. Felinine was detectable at 6 months of age in all cats (range, mean +/- SEM, nmol/mL, 13.8-801.1, 432.3+/-112.2, males and 34.3-393.0, 140.4+/-45.0 females). In entire males, felinine showed a biphasic pattern, peaking (2550 nmol/mL) between 11-13 months of age toward the end of the attainment of puberty then falling to a low (1048 nmol/mL) at 15 months of age then climbing to a peak (3661 nmol/mL) at 17 months of age. Natural plasma testosterone levels in entire males showed a similar biphasic pattern peaking (6.8 pmol/mL) at 12 months of age, falling (1.3 pmol/mL) at 15 months, and finally rising again (12.6 pmol/ml) at 16 months of age. Castration of half the male cats induced a parallel fall in both testosterone and felinine that was reversed following testosterone supplementation. Urinary felinine levels in entire females rose slowly throughout the study and reached 795 nmol/mL at 18 months of age compared to the level of 365 nmol/mL reached by the spayed females: these levels were not significantly different when expressed as felinine/creatinine ratios. We could not detect testosterone in either entire or spayed females and so concluded that felinine was unrelated to testosterone in these groups. There was strong evidence that plasma testosterone levels are positively correlated with urinary felinine levels in male cats. The control of felinine might be sex-linked and may be part of a pheromonal signaling process of the male cat.

Aging↗
PubMed1997

Urinary excretion of endogenous nitrogen metabolites in adult domestic cats using a protein-free diet and the regression technique.

The study was designed to determine urinary excretions of endogenous total, urea, ammonia and creatinine nitrogen in adult domestic cats. Endogenous urinary nitrogen metabolite excretions were determined by feeding adult cats a protein-free diet for 10 d or by regression to zero protein intake of the urinary nitrogen metabolite excretions of adult cats fed four levels of dietary protein. The mean (+/- SEM) endogenous total, urea and ammonia nitrogen excretions for the cats fed the protein-free diet were 360 (+/- 11.3), 243 (+/- 8.8) and 27.6 (+/- 1.06) mg x kg body weight(-0.75) x d(-1), respectively. Estimates of 316 (+/- 53.9), 232 (+/- 43.4) and 33.7 (+/- 5.68) mg x kg body weight(-0.75) x d(-1), respectively, were obtained using the regression technique. The differences in results between the two techniques were not statistically significant. Daily excretions of creatinine nitrogen were not significantly (P = 0.64) different between the protein-free and regression technique (mean +/- SEM, 14.4 +/- 0.49 and 15.9 +/- 1.05 mg/kg body weight(0.75), respectively). The endogenous urinary total and urea nitrogen excretion of adult domestic cats is higher than values for other mammals such as humans, dogs, rats and pigs.

Ammonia↗
PubMed1996

Correction for amino acid loss during acid hydrolysis of a purified protein.

Hydrolyzing a protein in acid for a single hydrolysis interval, normally 24 h, will lead to inaccurate estimates of the amino acid composition of that protein due to an effect of the time of hydrolysis on peptide bond cleavage and amino acid degradation. The simultaneous yield and decay of amino acids during the hydrolysis of a protein can be described by a compartmental model with parameters for the hydrolysis and loss rates specific to each amino acid in a protein. The amino acid composition of the protein prior to hydrolysis can be determined by nonlinear regression of data derived from multiple hydrolysis intervals. In the present study egg-white lysozyme was hydrolyzed in 6 M HCl using 18 hydrolysis intervals (range, 2-141 h) using the conventional duplicate hydrolyses/interval system. Hydrolysis and loss rates were determined for each amino acid. Increasing the number of hydrolysis intervals prior to the maximum point on the hydrolysis curve, and including an hydrolysis interval greater than 100 h increased the accuracy with which the hydrolysis and loss rates were estimated. Most of the amino acids underwent some degree of loss during hydrolysis. Of particular note was the loss rate for cysteic acid, which was greater than that found for serine which is commonly regarded as an acid-labile amino acid. The determined amino acid composition of the protein, based on the nonlinear regression of the data from four different series of hydrolysis intervals, was compared with the known amino acid composition (sequencing). Using the routine duplicate sampling system, a nonlinear regression including 10 hydrolysis intervals (2, 6, 10, 14, 18, 22, 26, 30, 60, and 141 h) resulted in a mean amino acid recovery of 100% (range, 94-110%) and provided an acceptable compromise between accuracy and the cost of analysis.

Amino Acids↗
PubMed1996

Gut endogenous nitrogen and amino acid excretions in adult domestic cats fed a protein-free diet or an enzymatically hydrolyzed casein-based diet.

Ileal and fecal gut endogenous nitrogen and amino acid excretions in adult domestic cats were determined. Ileal digesta were collected (10 cm of terminal ileum) from the cats fed either a protein-free diet or an enzymatically hydrolyzed casein-based diet (free amino acids and peptides < 10,000 Da) for 1 wk. Chromic oxide was included in each diet as an indigestible marker. The relative contribution of the hindgut to total endogenous gut excretion was investigated in a separate study by feeding cats a protein-free diet with or without added antibiotics for 10 d. Endogenous ileal nitrogen and amino acid nitrogen excretions of (mean +/- SEM 2.4 +/- 0.27 and 1.9 +/- 0.13 mg/g food dry matter intake, respectively, were found for the cats fed the protein-free diet, whereas higher excretions of 3.6 +/- 0.73 (P = 0.12) and 3.6 +/- 0.76 (P = 0.03) mg/g food dry matter intake were obtained in cats fed the enzymatically hydrolyzed casein. Significantly (P < 0.05) higher endogenous ileal amino acid excretions, for the enzymatically hydrolyzed casein-fed cats compared with those fed the protein-free diet, were found for methionine, aspartic acid, serine, glutamic acid, proline, valine and isoleucine, with the differences in excretions of glycine, alanine, leucine and histidine being significant at the 6% level. Most of the endogenous fecal amino acid excretions were unaffected by the inclusion of the antibiotics in the protein-free diet, although bacterial numbers were significantly lower (69%). Antibiotics addition led to significantly higher fecal endogenous excretions of nitrogen, taurine, threonine, serine and histidine but significantly lower excretions of methionine and lysine. Cats, like other simple-stomached mammals, excrete higher amounts of endogenous amino acids at the terminal ileum when the diet contains peptides.

Amino Acids↗
PubMed1995

Twenty-four hour felinine [corrected] excretion patterns in entire and castrated cats.

The purpose of this study was to determine the 24 h urinary excretion of a sulphur containing amino acid called felinine in entire and castrated cats of both sexes. Entire male cats excreted (mean +/- SEM) 122 +/- 23.6 mmol of felinine per kg bodyweight per day with castrated males, entire females and spayed females excreting 41 +/- 8.4, 36 +/- 7.3 and 20 +/- 3.8 mmol, respectively. There was an overall significant difference between groups in the amounts of felinine excreted in 24 h [F(3, 24) = 11.8, p < 0.0001] with there being significant differences between entire males and castrated males (p < 0.001) and castrated males and spayed females (p < 0.05). There was no difference in excretion between entire and spayed females. Urine volumes were not significantly different for the 24 h period. The differences in excretion levels were caused by different concentrations of felinine in the urine with entire male cats excreting (mean +/- SEM) 2.0 +/- 0.55 g of felinine per litre of urine. The data obtained in the present study support the concept that felinine, which has been found in Felidae species only, may be testosterone dependent. Felinine may be involved in territorial marking.

Amino Acids, Sulfur↗
PubMed1995

Felinine: a urinary amino acid of Felidae.

Felinine (2-amino-7-hydroxy-5,5-dimethyl-4-thiaheptanoic acid) has been identified in the urine of several members of the Felidae family including the cat (Felis catus). Rates of excretion of 95 mg/day have been recorded for entire male cats with entire female cats excreting around 19 mg/day. These high excretion rates in entire male cats may have a significant effect on the daily sulphur amino acid requirement. The isoamyl moiety of felinine seems to originate from the same isoprenoid pool as used for the synthesis of cholesterol in the cat. The sulphur in the felinine molecule appears to originate from cysteine, although some contradictory evidence exists. The site of synthesis and the method of transportation in the blood remain largely unknown. The biological significance of felinine to the animal is still a matter for speculation, but its function as a precursor to a pheromone seems likely. Recently, an accurate chemical assay for felinine has been developed that will allow investigation of felinine in different tissues and excretions and from a wider range of mammals.

Animals↗