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W Velle

Publications and source records attributed to W Velle.

At least 19 recordsLinked to original sources
PubMed1998

Apparent ruminal degradation and rumen escape of lysine, methionine, and threonine administered intraruminally in mixtures to high-yielding cows.

We studied the kinetics of lysine, methionine, and threonine in six high-yielding dairy cows at peak lactation (stage 1) and 6 mo later (stage 2). The cows were fitted with cannulas in the rumen and duodenum and were automatically fed every 4th h. The three amino acids (AA) were administered intraruminally in mixtures at dosages of 100, 200, 300, and 400 mmol of each, together with polyethylene glycol (PEG) as a liquid marker. Mean rumen liquid pools at stages 1 and 2 were not significantly different. The mean liquid outflow decreased from 13.6 to 9.5 L/h, and there was a significant linear increase in the liquid outflow with increasing dosages of AA. No significant interaction was found between feeding levels and AA dosages on rates of apparent degradation and rumen escape values. Expressed as percentages of the dosage, all three AA studied showed a significant linear decrease in degradation and a significant increase in rumen escape values with increasing dosage. At the feeding levels in stages 1 and 2, the highest relative degradation rates (percentage of dosage) were observed for threonine. The relative degradation rate of methionine was significantly lower than of lysine at the high feeding level but significantly higher at the low feeding level. The mean rumen escape values of threonine, methionine, and lysine across dosages and feeding levels were 16.7, 22.1, and 20.5%, respectively. The flow of the administered AA into the duodenum during an 8-h period after administration increased with increasing dosages, with peak concentrations after 1 h. Thus, the amounts of rumen escape of the three AA were considerable at all dosages, even when the AA were administered in unprotected form.

Animals↗
PubMed1998

Ruminal escape and apparent degradation of amino acids administered intraruminally in mixtures to cows.

The apparent ruminal degradation and escape of amino acids (AA) administered in 9 different mixtures of essential AA and 8 different mixtures of nonessential AA were studied using two cows fitted with ruminal cannulas. The 600-mmol AA mixtures, which were administered intraruminally using polyethylene glycol as a liquid marker, contained equal amounts of two, four, or eight AA. The amounts of each of the AA in the mixtures were 300, 150, and 75 mmol, respectively. Ruminal degradation and escape were compared with values previously reported for AA administered individually. Across doses, the mean rate of initial degradation (degradation during the 1st h after administration) of essential AA was 26% when the AA were administered in mixtures and 45% when the AA were administered individually. For nonessential AA, the corresponding values were 34 and 54%. Across doses, mean ruminal escape during the first 8 h after essential AA administration was 22% when the AA were administered in mixtures and 16% when the AA were administered individually. For nonessential AA, the corresponding values were 13 and 11%. After intraruminal administration of AA, both individually and in mixtures, significant negative correlations were found between rates of degradation during the 1st h and ruminal escape during an 8-h period. Some AA mixtures caused a net increase in the concentration of other AA in ruminal fluid 1 h after administration. Twelve of the mixtures that did not contain Ala caused a considerable net increase in the concentration of this AA, and 3 AA mixtures containing Arg and Ala caused a marked net increase in the concentration of Trp.

Alanine↗
PubMed1997

Rumen escape and apparent degradation of amino acids after individual intraruminal administration to cows.

Apparent rumen degradation and escape of 18 amino acids (AA) after individual administration intraruminally were studied using two nonpregnant, nonlactating, rumen-cannulated cows fed a ration containing hay and concentrate twice daily. The pulse-dosages of AA were 75, 150, 300, and 600 mmol. Polyethylene glycol was used as the liquid marker. Rates of apparent degradation during the first 60 min (initial degradation) varied markedly among the AA; rates were highest for Ser, Asn, Glu, and Gln and lowest for Tyr, Val, Arg, and His. At the 75-mmol dosage, which corresponded to an initial substrate concentration of about 1 mM of rumen fluid, initial degradation varied between 95 and 40% of the dosage, depending on the AA. Rates, expressed as percentages of the dosage, decreased as dosages increased. During the first 8 h after administration, escape of the AA increased from a mean of 9% at the lowest dosage to a mean of 21% at the highest dosage. At the highest dosage, Met caused a net increase in the concentration of 11 of the other AA in rumen fluid. Twelve of the AA administered caused a net increase in the concentration of Ala in rumen fluid. Methionine and Lys are among the AA considered to be limiting to milk yield. These AA showed relatively high rumen escape values and may be useful as feed supplements even in an unprotected form.

Amino Acids↗
PubMed1990

Androgens in fetal pigs in relation to sex of neighbour(s).

Concentrations of androgens in blood and/or fetal fluids were determined in pig fetuses 35, 56/58 and 115 days of age. For each fetus the sex of its neighbour(s) in utero was determined. Irrespective of the sex of neighbour(s), no significant differences in testosterone levels were found between the different groups of females, or between the different groups of males. When females and males were compared, significant differences were found. At a fetal age of 35 days testosterone concentrations (mean and SD) in amniotic fluid were 0.17 +/- 0.06 and 0.26 +/- 0.05 nmol/l in females and males, respectively (p less than 0.01). At a fetal age of 56/58 days, the corresponding values were 0.14 +/- 0.04 and 0.21 +/- 0.07 nmol/l (p less than 0.01). At this age testosterone concentrations in mixed umbilical blood plasma were 0.22 +/- 0.08 in females and 1.12 +/- 0.64 nmol/l in males (p less than 0.001). At term the mean concentrations of testosterone were 2.4 and 2.5 nmol/l in mixed umbilical blood plasma and 1.6 and 1.7 nmol/l in fetal fluid in females and males, respectively. The levels of dehydroepiandrosterone in fetal fluid at this stage were 1.6 nmol/l in females and 1.7 nmol/l in males. Concentrations of dihydrotestosterone were below the sensitivity level of the method (less than 0.09 nmol/l) in all samples tested. It is concluded that male neighbours do not influence the androgen levels in blood plasma and fetal fluids of the females.

Amniotic Fluid↗
PubMed1989

Effect of ovine urine and some of its components on viability of nematode eggs and larvae in sheep faeces.

Sheep faeces incubated for 7 days at 27 degrees C for cultivation of third-stage nematode larvae were sprinkled daily with urine from sheep or with solutions of components normally occurring in sheep urine. Larval development was completely blocked in cultures sprinkled either with sheep urine, with solutions of 2 or 4% urea, or with urine from which urea or the phenol components had been extracted. Only a few third-stage larvae developed in cultures sprinkled with 1% urea. Normal larval development occurred in cultures sprinkled with either the phenol component from urine, or with solutions of 0.035% phenol, 0.035% p-cresol, 0.3% allantoin, 0.3% hippuric acid or 2.8% NaCl. Normal larval development also occurred in all control cultures sprinkled with water, including one culture where there was urine in the space between the outer and inner beaker used for cultivation. It is suggested that the inhibitory effect of urine on larval development is mainly caused by ammonia produced when urinary urea is brought into contact with urease of faecal origin. It is, however, an unsolved question why urine, from which urea had been removed, also inhibited larval development.

Animals↗
PubMed1989

Degradation and outflow of amino acids from the rumen of sheep.

1. In hay-fed, cannulated sheep the apparent degradation in and outflow from the rumen were determined for graded doses of mixtures of the amino acids lysine, threonine and methionine, administered intraruminally and using polyethylene glycol (PEG) as a liquid marker. The doses ranged between 2.5 and 15 g for each amino acid in the mixtures. 2. Relative rate of apparent degradation in the first 4 h was highest for lysine, and lowest for methionine. The apparent degradation in 24 h was highest for lysine and lowest for threonine. Conversely the fraction flowing out of the rumen in intact form in 24 h was highest for threonine and lowest for lysine. Rates of apparent degradation as well as outflow were dose-dependent. 3. The validity of the estimated outflow of amino acids from the rumen was corroborated by measurements of concentrations of the amino acids in duodenal contents and in blood plasma which were also dose-dependent. 4. It was concluded that part of the requirement for the essential amino acids threonine and methionine may be met, even when these amino acids are delivered in unprotected form, given as a feed supplement.

Amino Acids↗
PubMed1989

Ruminal degradation and outflow of amino acids in cows.

Two rumen- and duodenum-cannulated cows were used to study the disappearance rate, degradation in, and outflow from the rumen of four amino acids administered individually into the rumen at the following dose levels (mmol): lysine 273-547-820, tyrosine 276-496-828, isoleucine 381-762-1143 methionine 335. Calculations were based on the use of PEG (polyethylene glycol, 4000) as liquid marker for determination of the volume and dilution rate of rumen fluid. At the same dry matter intake a comparison was made between the influence of a high-forage and a low-forage diet. At the lowest dose level, the initial rates of disappearance (mmol/l per h) were 0.52 for lysine, 0.48 for tyrosine, 0.55 for isoleucine and 0.58 for methionine. The rates increased with increasing dose levels. The fractions of administered amino acids flowing out of the rumen and the fractions degraded in the rumen were studied over an 11 h period. At the lowest dose level, outflow (mmol/11 h) amounted to 42 and 54 for lysine, 36 and 29 for tyrosine, 93 and 48 for isoleucine, 104 and 75 for methionine on the high and low forage diet, respectively. The corresponding figures for degradation were 232 and 209, 239 and 247, 287 and 333, 226 and 259 mmol/11 h. The fractions of an administered amino acid flowing intact out of the rumen increased, and the fractions degraded in the rumen decreased, with increasing doses.

Amino Acids↗
PubMed1983

Relationship between growth rate in bulls and human chorionic gonadotropin-induced plasma testosterone concentrations.

In the selection of bulls for breeding purposes growth rate is an important characteristic. In this study 411 bulls, 5 to 11 mo of age were subjected to a human chorionic gonadotropin (hCG) stimulation test. Plasma testosterone 7 h postinjection of hCG was related to monthly weight gain in the month of blood sampling and to daily gain from 3 to 11 mo of age. The bulls were divided into two groups according to plasma testosterone concentrations; those with values above and those with values below the average for each age group. Over all ages (5 to 11 mo), the bulls in the high testosterone group had higher monthly (P less than .001) and daily (P less than .025) weight gain than those in the low testosterone group. However, when split into two groups according to age (5 to 7 and 8 to 11 mo), only the older animals showed the relationship described above. The results indicate that determination of plasma testosterone might supplement other criteria in the selection of breeding bulls for beef production. Eight to 11 mo of age, when differences between high and low levels of testosterone were greatest, would appear to be the most suitable period for sampling.

Animals↗
PubMed1980

Plasma concentration of testosterone in young bulls in relation to age, rate of weight gain and stimulation with human chorionic gonadotrophin.

In 86 bulls ranging in age between 3 and 11 months, the maximal plasma testosterone concentration (n = 7 as well as the mean concentration (n = 7), same samples) were found to increase with age to peak values at 7-8 months with a subsequent decrease. The multiple correlation coefficient for monthly gain as a function of testosterone concentraton and age was 0.85 (P < 0.001), for monthly gain as a function of age 0.84 (P < 0.001) and for monthly gain as a function of testosterone concentration 0.44 (P < 0.001). The deviation in levels of measured plasma testosterone from the curve expressed by multiple regressiuon analyses of testosterone concentration as a function of age was correlated with the average daily weight gain during the testing period of 9 months and found to be not significant (r = 0.21). The difference between concentrations of plasma testosterone after stimulation with human chorionic gonadotrophin (HCG) and the spontaneous maximal concentration of this hormone was not signifiant. High correlation coefficients were found between maximal (r = 0.8) and mean (r = 0.6) concentratiaons of plasma testosterone before and after an injection of HCG (P < 0.001).

Aging↗
PubMed1976

Endogenous anabolic agents in farm animals.

This presentation is limited to the three groups of steroid sex hormones which alone or in combination have been shown to be anabolic when used in farm animals. It seems essential for realistic evaluation of public health aspects of use of these hormones that the discussions include naturally occurring levels of the hormones. The following topics will be dealt with for each group of hormones: 1. Types and sources; 2. Production rates; 3. Plasma levels; 4. Tissue concentrations; 5. Metabolism and excretion. Gestagens. Progesterone and 20-dihydroprogesterones are mainly produced in ovaries and placenta. Production rates are estimated to 10 and 14 mg/24 hrs in pregnant goats and sheep, respectively. Plasma levels during the luteal phase are of the order of 2--10 ng/ml, during pregnancy somewhat higher. Muscular tissue from calves contain 0.25 mg/g. In dairy cows progesterone is excreted with the milk which contains up to 30 ng/ml; butterfat up to 300 mg/g. In ruminants progesterone is metabolized mainly to androgens excreted with faeces. In pigs large parts are metabolized to pregnanediols excreted with urine. Androgens. Testosterone is mainly secreted by testes. Boar testes also produce large amounts of dehydroepiandrosterone and its sulphate. Production rates have been estimated to be 10 mg and 40--50 mg/24 hrs. in boars and bulls respectively. Plasma levels in bulls and rams are generally 2--10 ng/ml, in boars 2--25 ng/ml. Adipose tissue levels up to 22 ng/g are reported for bulls. In ruminants epitestosterone seems to be a major metabolite excreted mainly with faeces. In boars, urinary 11-deoxy-17-ketosteroids are major metabolites of testicular dehydroepiandrosterone. Castration shows elimination to be rapid. Estrogens. 17beta-Estradiol and estrone are produced in ovaries and placenta and, in large amounts, in boar and stallion testes. Production rates in late pregnancy are estimated to 10 mg oestrone/24 hrs. in goats, 2 mg estrone and up to 28 mg 17beta-estradiol/24 hrs. in sheep. In cows much higher values are found. Boars and stallions produce huge amounts daily. Plasma levels in non-pregnant animals are at the pg/ml level. In late pregnancy levels of 2--4 thousand pg/ml are encountered in sows and cows, in sheep and goats lower levels. Calf muscular tissue contains up to 410 and 610 pg/g of estrone and 17beta-estradiol respectively. In muscle from pregnant heifers corresponding values were 120 and 860 pg/g in the 4th month and 2100 and 370 pg/g in the 9th month of pregnancy. Ruminants in large measure metabolize 17 beta-estradiol and estrone to 17alpha-estradiol which possesses low estrogenic activity. In pigs estrone dominates in blood and urine. Major routes of elimination arre with faeces in ruminants, with urine in pigs and horses. Elimination rates are high. Results obtained during the last few years clearly show that all three groups of steroid sex hormones occur in considerable concentrations in plasma and tissue...

Androstenedione↗