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Biomedical subjects

W Jentsch

Publications and source records attributed to W Jentsch.

At least 73 records · Page 4Linked to original sources
PubMed1987

[The energy requirement of young female cattle. 1. Research overview and body weight development of the animals].

In the period of 1975-1982 6 experiments with young female cattle of various rearing intensities were carried out. The respiration trial technique for the measuring of energy and protein metabolization in connection with the registration of a number of rumen physiologic data were applied together with comparative studies of the digestibility and the rumen fermentation of the rations used with young cattle and with fully grown sheep. The extent of the experiment was characterized by 695 metabolism periods in calves and young cattle as well as by 149 comparative studies of the digestibility and the rumen metabolism of the fully grown sheep. The results ascertained are the basis of the derivation of the energy requirement for the rearing of young female cattle according to factorial criteria. This first out of six papers on these experiments comprises an outline of the experiment arrangement, the material and the methods as well as of the live weight development of the animals. In four of the six experiments there was a continuous monthly registration of the measured values over the complete period of the rearing of the weaned calves up to their calving with four animals each under conditions of extremely high (experiment 1), medium (experiments 5 and 6) and low (experiment 3) rearing intensity. Experiments 2 and 4 provide additional information on rearing periods under special consideration of the gestation period. In experiment 1 the cows were not milked after the first calving, and measuring was continued to the second calving of the animals.

Animal Feed↗
PubMed1987

[The energy requirement of young female cattle. 2. Substance and energy metabolism].

The second installment of information on studies over several years of the energy requirement of young female cattle comprises data of the feed intake, the digestibility and metabolizability of the rations used as well as the nitrogen and energy balances of the test animals in six experiments with varying rearing intensities, in which the N, C and energy balances as well as rumen physiologic values were measured monthly using the respiration test technique. Of four experiments, measured values are available over the whole rearing period from calf to calving. The results received from 680 interpretable test periods are-separated for the six experiments--arranged in aggregate form according to live weight range in order to characterize the development of nutrient and energy metabolization processes at various rearing intensities. The results form an essential basis for the derivation of the energy requirement of young female cattle according to factorial criteria.

Animal Feed↗
PubMed1987

[Energy requirement of young female cattle. 3. Reproduction and products of conception].

The results with regard to reproduction obtained from a study lasting several years of the energy requirement of young female cattle reared with different intensity are described. It becomes apparent that there are relations between feeding, rearing intensity and insemination expenditure. Age and weight at the time of conception in the individual test series averaged between 290 and 630 days and 270 and 430 kg respectively. The weight of the conceptional products of 31 calvings was registered and, according to Jakobsen (1956, 1957), the energy and N content of the conceptional products was proportionally assigned to the prenatal test periods. In the last 140 days of gravidity the N balance per animal and day increases from 16 to 23 g. N retention of the cows is low in the last days of gravidity. The utilization of metabolizable energy for the development of conceptional products is calculated as a conventional comparative value provided the maintenance requirement per unit metabolic body weight of the cows and the utilization of metabolizable energy for energy retention in the cows on an average of 156 individual values of 12 +/- 8% are the same and correspond in their magnitude to analogous findings of other authors, mainly compiled from dairy cows.

Animals↗
PubMed1981

[Energy requirement of growing bulls].

The series of experiments concerning the utilisation of feed energy by growing bulls (482 total metabolism periods) as described in this periodical in four articles (Schiemann and others 1976; Jentsch and Schiemann 1976; Jentsch and others, 1976; Hoffmann and others, 1977), has undergone further statistical processing in order to test possibilities of factorial analysis for the derivation of values for the energy requirement of growing bulls. Square equations for the characterisation of the maintenance requirement of metabolisable energy and net-energy-fat in kJ/kg live weight 0.75 and day were derived for the live weight range between 50 and 335 kg (see equations (2) and (4)). Beyond this live weight range the maintenance requirement of growing bulls-- related to the metabolic body weight -- corresponds to that of fullgrown oxen (410--420 kJ metabolisable energy/kg live weight 0,75 and day). The analysis of the energy content for the live weight increase in dependence on the live weight resulted in the statistical generalisation characterised by equation (5) for live weights above 200 kg. Up to 200 kg live weight the energy content of the live weight gain is between 8 and 10 MJ/kg live weight gain. Above that, equations for the characterisation of the energy requirement of fattening bulls in ad libitum feeding were derived for the live weight ranges between 200 and 335 kg as well as 335 and 550 kg (cf. equations (2) and (3)). The significance of the factorial analysis of the energy metabolism of growing animals is discussed comparatively to previous assessments.

Aging↗
PubMed1980

[Influence of various physical forms of the feed on the energy metabolism of ruminants. 2. The influence of the mechanical treatment of the feed on rumen fermentation].

The influence of various physical forms of the feed on energy utilisation was comparatively investigated in a total of 170 experiments with the complete metabolism and 28 digestibility experiments with fullgrown sheep. The roughage feedstuffs dried green fodder of vetch/grass, lucerne and rye grass and straw were fed in 9 rations with different quotas of concentrates (0 to 60%) to 4 parallel animals. The roughage underwent the following 5 methods of mechanical treatment: 1) chopping; 2) chopping and pelleting; 3)grinding; 4) grinding and pelleting; 5) chopping and pelleting with concentrates. On the whole, no significant influence of the different methods of mechanical treatment on rumen on the basis of the characteristic data acetic acid, propionic acid, butyric acid, acid total, pH-value and NH3-content during the course of the day (sampling 2.5 to 3, 4 to 4.5, 5.5 to 6, 7 to 7.5, 15.5 to 16 hours after feeding). On an average of the 9 rations the rumen fluid sampled 2.5 to 3 hours after feeding merely showed a growing tendency of the quota of acetic acid and a corresponding decrease of the quota of propionic acid according to the degree of fineness of the roughage.

Animal Feed↗
PubMed1980

[Influence of various physical forms of the feed on the energy metabolism of ruminants. 3. Investigation of the energetic utilisation of rations with roughage treated with various mechanical methods].

In a total of 170 experiments with the complete metabolism of fullgrown sheep the energy utilisation of rations with roughage treated with different mechanical methods was investigated. The roughage feedstuffs dried green fodder of vetch/grass, lucerne and rye grass and straw were given to 4 parallel animals in 9 rations with differing quotas of concentrates (0 to 60%). The roughage underwent the following 5 methods of treatment: 1) chopping; 2) chopping and pelleting; 3) grinding; 4) grinding and pelleting; 5) grinding and pelleting with concentrates. The results show that the bases given in the GDR system of feedstuff evaluation concerning the energetic evaluation of feedstuffs are to be applied to mechanically treated roughage too. In order to avoid negative effects on the energy metabolism one has to take care that the use of mechanically treated roughage does not cause dysfunctions of the rumen.

Animal Feed↗
PubMed1979

[Utilization of feed energy by growing pigs. 3. Energy requirement for the growth and fattening of pigs].

The test series for the investigation of the energy consumption of growing pigs of the breeds large white and improved land race pig as well as cross breeds of the two breeds in a total of 369 metabolism periods (as described in the first two pieces of information of this publication series -- Hoffmann and others, 1977 and Jentsch and Hoffmann, 1977) were statistically analysed for the purpose of the derivation of the energy requirement for maintenance and the partial energy requirement for growth in order to test the possibilities of the factorial analysis for the derivation of energy requirement values of growing pigs. The dependence of the maintenance requirement of growing pigs (investigations in the live weight range of 10 to 40 kg -- see 1st information--were made with boars those in the live weight range of 30 to 120 kg were made with gelded boars, 2nd information) on the live weight can best be characterised by applying a power exponent of 0,61 or 0,62 for the live weight. A definition is offered to be discussed for the energetic maintenance requirement of productive live stock and laboratory animals as a conventional value. The energy requirement values derived from the doubly-factorial statistical analysis show a satisfactory adaptation to the measured values as such concerning energy intake and observed growth performance of the test animals. The conclusion is drawn that the factorial analysis of the energy requirement (maintenance plus partial performances) results in a better estimate of the requirement of growing animals than the assessment according only to live weight and live weight increase without characterising the energy requirement for partial performances. This is important for the further working on and more exact definition of requirement norms.

Animal Feed↗
PubMed1978

[Energy metabolism and energy requirements of growing boars].

The nitrogen and energy metabolism and the energy consumption of growing boars were measured in 2 metabolic and feeding trials using 8 parallel animals each. The studies covered the 30 to 150 kg live weight range. The growth intensity of the boars was found strongly influenced by the protein level of the ration. At a crude protein level of 18% in the ration, the boars gained, on the average, 780 g per day during the fattening period under study. Energy conversion was found to decline as the protein amount went up. The energy expediture for protein deposition was estimated at 1.8 to 2.0 kcal metabolizable energy per kg deposited. The energy and feed expenditures were calculated to be 7.1 Mcal net energy--fat retention for the whole development period or 3.0 kg dry matter per kg live weight. Boars proved to have an energy requirement differing from that of barrows and gilts; equations are presented for derivation.

Animals↗
PubMed1978

[Digestibility and utilization of rations containing differently treated straw. I. Digestibility by sheep of rations containing differently treated straw].

During 63 digestibility periods of adult sheep, the digestibility of wheat and oat straw sujected to different kinds of treatment was compared. The straw was fed in the following forms: chopped, chopped and treated with 6% sodium hydroxide, pelleted without and with NPN-addition (ammonium bicarbonate and/or urea) during pelleting. Notwithstanding pressing temperatures over 90 degrees C and light moistening of the straw during pellet production, the addition of the two NPN-components did not allow to increase digestibility and energetic feed value. Two replications averaged an increase in energetic feed value by 42% due to NaOH-treatment. Energy digestibility went up by 39 to 55%, and energy concentration increased from 322 to 457 energetic feed equivalents (cattle) per kg DM. In addition, a number of rumen-physiological indices were obtained.

Animal Feed↗
PubMed1978

[Digestibility and utilization of rations containing differently treated straw. 2. Energetic utilization by sheep of rations containing differently treated straw].

A total of 59 complete metabolic periods of adult sheep were used to compare energy balance and energy utilization of rations containing 45, 60 and 99% of straw previously subjected to different treatments. In addition, some indices of rumen physiology were determined. The straw was fed in the following forms: chopped, chopped and treated with 6% sodium hydroxide, pelleted with and without NPN-addition (ammonium bicarbonate and/or urea) during the pelleting process. Notwithstanding pressing temperatures above 90 degrees C during compaction, the addition of NPN-compounds did not result in increased digestibility. The NaOH-treatment of the straw increased the energy digestibility of the ration containing 45% straw by 5 to 6 digestibility units. All experiments revealed a higher energy balance and, consequently, a higher energy utilization than could be expected from calculations on the basis of equations derived from earlier experiments with adult sheep. The variations are discussed under the aspect of energetic feed evaluation and with regard to consequence for the efficient use of straw in rations for ruminants.

Animal Feed↗
PubMed1978

[Digestibility and utilization of rations containing differently treated straw. 3. Energetic utilization by fattening bulls of rations containing differently treated straw].

In 136 complete metabolic periods of fattening bulls (live weight range 250 to 440 kg) comparative studies were performed on rations containing 30 to 40% straw previously subjected to different treatments. In addition, several rumen-physiological and blood indices were determined. Chopped straw without and with NaOH (6%) treatment and straw pellets without and with NPN-addition (ammonium bicarbonate and/or urea) during the pelleting process were used. No significant differences were found between comparable rations as to energy digestibility. The rations containing 60% straw revealed a higher evergy balance and, consequently, a higher energy utilization than could be expected from calculations on the basis of equations derived from previous experiments with adult steers. The importance of straw as energy source for ruminant feeding is highlighted.

Animal Feed↗
PubMed1976

[The effect of addition of formic acid to the rations on the energy metabolism of sheep and young bulls].

Total metabolism trials were carried out with 8 fattening bulls and 4 male sheep receiving rations supplemented with formic acid. Comparative trials were performed with lucerne conservates. The following results were obtained: Formic acid supplements of up to 0.7 gm/kg liveweight per animal/day did not influence the ruminal fermentation and the digestibility of the food beyond ordinary dissimilation processes nor did they influence the energy turnover in the animals. Already in the rumen, the added HCOOH was largely broken down into CO2 and CH4. Higher levels of N retention were observed if the animals were fed fresh lucerne silage supplemented with formic acid as compared with dried green feed and the other types of silage.

Animal Feed↗