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Biomedical subjects

E Teller

Publications and source records attributed to E Teller.

At least 19 recordsLinked to original sources
PubMed1992

Nitrogen metabolism in rumen and whole digestive tract of lactating dairy cows fed grass silage.

Effects of wilting of grass prior to ensiling on OM intake, ruminal digestibility, efficiency of bacterial protein synthesis, and amount and composition of duodenal N fraction were examined using four lactating Holstein cows. Direct-cut or wilted grass silages were fed for ad libitum intake and supplemented with 5.0 or 5.3 kg of concentrate, respectively. Milk yield was 18.1 and 21.2 kg/d with direct-cut versus wilted silage, and milk protein and fat contents were 2.63 and 4.60% with direct-cut versus 2.75 and 4.27% with wilted silage, respectively. Wilting of the grass (from 17 to 38% DM) increased OM intake but had no effect on ruminal digestibility. Total N flow and amounts of different AA in proximal duodenum were increased, and the difference was principally of bacterial origin. The efficiency of bacterial protein synthesis in rumen was related to dilution rate of liquid phase and to the time devoted to ruminating. These results indicate that the passage of bacterial protein to the lower digestive tract is a key factor for improving the assimilation of the soluble N fraction of grass silage and that this phenomenon is related to chewing activity.

Ammonia↗
PubMed1990

Probiotics in animal nutrition: a review.

The normal microflora colonizing the digestive tract in livestock species at five to six days after birth can be summarized as following: 400 to 500 different bacterial strains for a total count of 10(14) bacteriae. The role of the gut flora is multifarious: fermentation of feed compounds, induction of anatomical and physiological changes in the intestinal cell wall structure, increase in animal resistance against enteropathogenic bacteriae, etc. In the present review, the numerous hypotheses for explaining the beneficial effects of probiotics on zootechnical performances and also the healthy aspects for men and animals are summarized, and the possible mechanisms of bacterial attachment are enumerated. The different assumptions on mode of action and fixation mechanisms of probiotics in the gut are critically discussed, and the required characteristics of the ideal probiotic are listed. Finally, some zootechnical results obtained with lactic acid bacteria are shown for calves, piglets and broilers.

Animal Nutritional Physiological Phenomena↗
PubMed1990

Effects of chewing behavior and ruminal digestion processes on voluntary intake of grass silages by lactating dairy cows.

Four primiparous Holstein-Friesian cows (518 kg average BW) with ruminal and duodenal cannulas were used to examine voluntary intake of direct cut (DC) or wilted (W) grass silage in relation to ruminal characteristics and chewing behavior. Dry matter content of the silages was 17.0 and 38.1%, concentrate DM intake was restricted to 5.0 and 5.3 kg/d, and voluntary DM intake from silages averaged 7.4 and 9.5 kg/d (P = .008), respectively. The acetate/propionate ratio in ruminal fluid decreased from 4.0 on DC to 3.3 on W silage (P = .021). The protein content in milk increased from 26.3 to 27.5 g/liter (P = .042) and the protein yield from 469 to 574 g/d (P = .038). The distribution of concentrates (38% of DM intake) with a mean particle size of .04 cm reduced differences in fecal mean particle size between diets. There was a shift from eating to ruminating on W silage with regard to daily duration (min/d) and number of jaw movements (no./d). However, ruminating index (no./kg DM intake) remained unchanged, irrespective of wilting and chop length of the silages or physiological state of the animals. These results are interpreted to indicate that the time lag for functional density of feed particles in the reticulorumen to increase, as affected by ruminating activity, not rate of reduction of the particle size, limits voluntary intake of grass silage by cattle.

Animals↗
PubMed1990

[In sacco degradability of grass silage and bacterial contamination of residues].

The in sacco degradability of wilted grass silage, harvested at 2 stages of maturity, and of direct cut silage was determined in 6 heifers. The date of cutting had a pronounced effect on ruminal degradation and bacterial contamination of the feed residues. On the contrary, wilting of the grass prior to ensiling did not influence these parameters.

Animals↗
PubMed1989

Protein and energy relationships in dairy cattle. 1. Dry cows.

Nitrogen metabolism in ruminants is a dynamic process depending on level of intake and composition of dietary dry matter and on the physiological state of the animals. These parameters were analysed in a regression model for the requirements of nitrogen absorbed in the small intestine in relation to nitrogen balance of dry cows fed at maintenance level. The amount of total dietary nitrogen and the apparent nitrogen digestibility vary notably according to energy intake and energy concentration in dietary dry matter. On the contrary, the amount of nitrogen absorbed in the small intestine is only slightly affected by these parameters. The discrepancy between these statements lies mainly in differences in intestinal nitrogen absorption and in altered fermentation processes of the large intestine in response to changes in energy supply and ME concentration in dietary dry matter.

Animals↗
PubMed1989

Protein and energy relationships in dairy cattle. 2. Lactating cows.

Nitrogen requirements of lactating cows were calculated by means of statistical relationships established for nitrogen excretion in faeces and urine, for nitrogen balance, and for nitrogen flow in proximal duodenum and terminal ileum. The data used for elaboration of the relationships came from simultaneous measurements of nitrogen and energy balances. It appears that an increase in dietary nitrogen solubility augments total nitrogen and apparently digestible nitrogen requirements of the animals because of higher urinary nitrogen losses. This effect can be off-set by an increased metabolizable energy intake. High proportions of concentrates in the diets cause a shift in nitrogen excretion from faeces to urine. Requirements of intestinal absorbed nitrogen and its conversion into milk protein are dependant of dietary nitrogen solubility and metabolizable energy concentration, while they are favourably influenced by energy supply. Crude protein concentration is not an adequate way for expressing optimal protein supply in lactating cows because it may vary between 11.2% and 20.0% according to dietary characteristics for the same animal.

Animals↗
PubMed1989

Intake of direct cut or wilted grass silage as related to chewing behavior, ruminal characteristics and site and extent of digestion by heifers.

Six nonpregnant Friesian heifers (516 kg avg BW) with ruminal and duodenal cannulas were used to examine intake of direct cut (DC) or wilted (W) grass silage in relation to chewing behavior, ruminal characteristics and site and extent of digestion. Dry matter content of the silages was 20.3% and 40.3%, and feed intake averaged 1.88% and 2.17% of BW (P less than .01), respectively. Mean ruminal osmolality was 291 mosm/liter for the DC and 318 mosm/liter for the W silage (P less than .05), with extreme values exceeding 350 mosm/liter for the W silage at 1 h to 2 h postfeeding. There was a shift from eating to ruminating on W silage associated with a longer duration of the average rumination bolus cycle (P less than .01). Duration of chewing time per kilogram of DM intake was 103.5 min and 91.7 min (P less than .05) for the DC and W silages, respectively. Fecal mean particle length was 2.2 times greater (P less than .01), accompanied by higher spread coefficients (P less than .001), for the W silage. No differences occurred between silages in ruminal digestibility of OM and NDF. In the total digestive tract, apparent digestibilities of OM and NDF were depressed after wilting grass prior to ensiling (P less than .01), but the proportion of digestible OM apparently digested in the rumen was .74 for both silages.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1989

Apparent digestibility of nitrogen in rumen and whole tract of Friesian cattle fed direct-cut and wilted grass silages.

Spring grass consisting of Lolium perene L. (81%), Poa pratensis L. (9%), and annual weeds (5%) was stored as direct-cut or as wilted silage and used in feeding trials to determine the effects of wilting on N utilization. Six mature Friesian cattle, fitted with rumen and simple duodenal cannulae, were fed the silages for ad libitum intake in a crossover design consisting of two 49-d periods. Wilting increased intake of organic matter and decreased ruminal apparent digestibility or organic matter and whole tract apparent digestibilities of organic matter, NDF, and total N. Rumen degradability of silage N was increased by wilting (.7 vs. .67). Direct-cut silage, in comparison with wilted silage, provide (g/d) less N intake (232 vs. 286) and lower duodenal flows of total N (215 vs. 293), non-NH3 N (202 vs. 280), microbial N (111 vs. 177), and total amino acids (1056.8 vs. 1342.7). Duodenal flows of NH3 N and undegraded N were not different between silages. Efficiency of bacterial N synthesis in rumen was higher for wilted than for direct-cut silage (32.3 vs. 21.4 g N/kg organic matter apparently digested in rumen). It was concluded that wilting increase silage intake, rumen bacterial synthetic efficiency, and duodenal flow of non-NH3 N in cattle.

Animals↗
PubMed1986

Some attempts to improve the nutritive value of urea for dairy cows. 3. Its adjunction to fermentable carbohydrates: starea.

Starea, an intimate mixture of gelatinized wheat starch and urea, was tested again urea with regard to the ammonia release in the rumen, the amount and composition of the nitrogen fraction reaching the intestine, the nitrogen and energy balances, and the performance of lactating cows. Maize silage was the basal feed in all experiments. The ammonia concentration in the rumen liquor was measured in two cows fitted with a permanent rumen cannula. The curve of the ammonia concentration was about the same with both nitrogen supplements, and peaked at about 250 mg/l (14.7 mmol/l) two hours postfeeding. Two dry cows fitted with a re-entrant cannula at 10 cm from the pylorus were fed with maize silage supplemented with increasing amounts of either urea or starea. The duodenal nitrogen flow rapidly levelled off with both supplements and no significant difference between them could be detected. The amount of ammonia in the duodenal digesta remained very low. Nitrogen digestibility measured in lactating cows was not noticeably affected when starea instead of urea was added to maize silage. However, nitrogen excretion in the urine tended to decrease, while nitrogen secretion in milk was augmented with starea. The digestibility of the rations and their metabolizable energy supply were not significantly affected, and milk production was quite the same with both supplements, apart from the higher amount of milk protein obtained with starea compared with urea. As a general conclusion from the whole work conducted on the nutritive value of urea for lactating cows, it can be stated that the decline in performance of the animals after substitution of urea for conventional protein is mainly due to a decrease of the metabolizable energy concentration in the diets. None of the attempts tested in an effort to improve the nutritive value of urea was able to overcome this difficulty.

Ammonia↗
PubMed1984

The association of maize silage with urea: the effect on the ammonia content of the rumen fluid, the N flow in the duodenum, the nitrogen and energy balances and the milk production.

In different experiments, the nutritive value of maize silage associated with urea was compared with that of the same forage without any N supplement. The ammonia concentration in the rumen liquor was measured with two dry cows fitted with a permanent rumen cannula. Urea was rapidly hydrolysed in the rumen and gave rise to high ammonia concentrations. The control diet did not supply enough fermentable nitrogen to the ruminal flora. The duodenal N flow was measured with two dry cows fitted with a re-entrant cannula at 10 cm from the pylorus. When increasing amounts of urea were fed, the duodenal N flow initially increased to a maximum, but it leveled off with higher amounts of urea in the diet. With 13 cows in the second part of lactation, the feeding of urea increased the nitrogen balance of the animals and the metabolizable energy density of the rations. However, the milk production and the milk protein secretion were only slightly enhanced.

Ammonia↗
PubMed1984

The substitution of soybean meal for urea: the effect on the ammonia content of the rumen fluid, the N flow in the duodenum, the nitrogen and energy balances and the milk production.

In different experiments, the nutritive value of maize silage associated with urea was compared with that of the same forage associated with soybean meal. The ammonia concentration in the rumen fluid was measured with two dry cows fitted with a permanent rumen cannula. Urea gave rise to much higher NH3 concentrations compared with soybean meal. The duodenal N flow was measured with two dry cows fitted with a re-entrant cannula at 10 cm from the pylorus. Adding increasing amounts of either of the two N supplements to the maize silage showed that they were equivalent with low N intakes. However, clearly more N reached the intestine with soybean meal than with urea when the N intake increased. With 33 cows in the second part of lactation, the substitution of soybean meal for urea decreased the urinary N loss. At the same time, it significantly increased the mammary protein secretion and the milk production. The increase of the dietary metabolizable energy density noted under these feeding conditions corresponded to about two thirds of the increase of the milk production. Milk composition was only slightly affected.

Ammonia↗
PubMed1982

Intensity changes in the Doppler effect.

When a source moves in any direction, the source strength and the frequencies are altered by the Doppler effect. It is shown that the source strength divided by the cube of the frequency is a Lorentz invariant.

Journal Article↗
PubMed1978

Calcium digestibility in cows as influenced by the excess of alkaline ions over stable acid ions in their diets.

1. Statistical analyses were carried out on results obtained under strictly-controlled conditions in metabolism stalls with forty-one different rations fed to 127 adult non-pregnant dry cows, and with fourteen other different rations fed to thirty-five adult non-pregnant lactating cows that had calved 2-6 months earlier and whose daily milk production ranged from 11 to 20 kg. 2. Correlations between calcium digestibility and values for the sum of the alkaline ions sodium and potassium minus the sum of the stable acid ions chloride, sulphate and phosphate were calculated for all fifty-five experimental diets. 3. The results showed that the excess of the anions over the cations, in rations maintaining a positive Ca balance but not in rations allowing a negative Ca balance, increases the absorption of Ca from the intestine. Phosphorus, not alone but with chloride and sulphate, is the most important component of this effect.

Animals↗
PubMed1977

Electromagnetism and gravitation.

Generation of electric fields in rapidly rotating insulators is discussed and calculated. An interesting effect is expected in TlCl. A possible appearance of magnetic fields near rapidly rotating gravitating bodies is proposed. The simple suggestion made here would lead to magnetic fields of negligible magnitude.

Journal Article↗