The energy metabolism of growing swine in the body weight range of 10-50 kg. 2. Nitrogen and energy metabolism

Investigations were carried out about nitrogen and energy metabolism feeding rations with 17-24 and 44-47% crude protein content on maintenance and growing level to castrated male hybrid pigs of line 150. In growing periods the N deposition amounted to 10 g/animal.d (15 kg live weight), 18 g/animal.d (30 kg LW) and 21 g/animal.d (greater than 40 kg LW) on lower protein feeding level. In experiments with higher protein feeding level the corresponding results were 17, 22 and 22 g N deposition/animal.d. The partial utilization of metabolizable energy for deposition amounted to 70% for the rations with 17-24% protein content and to 59% for the rations with 44-47% protein content, without correlation to the animals development and the alternation in the protein feeding level. The results of regression analysis about maintenance requirement were 814, 775 and 806 kJ metabolizable energy/kg LW0.62.d in trials feeding rations with 17-24% crude protein content as well as 764, 846 and 818 kJ metabolizable energy/kg LW0,62.d in trials feeding rations with 44-47% crude protein content. 1,5-1,8 MJ metabolizable energy were used per MJ protein energy deposition and 1,3-1,4 MJ per MJ fat energy deposition respectively. The energy deposition per kg live weight gain amounted to values between 9 (10 kg LW) and 18 MJ (60 kg LW).     

The energy maintenance requirement of growing pigs of different sexes give normal and high protein diets. 2. Experiments in sows

Six animals each out of 12 female fattening hybrids (150 X (L X E] were given rations containing 17 or 45% crude protein resp. 4 periods of growth feeding alternated with 5 periods of maintenance feeding in the live weight range between 33 and 146 kg. The feeding level did not have an influence on the level of digestibility. From the experiments with 17% crude protein in the ration 1004 and from those with 45% crude protein 947, on average 977 kJ metabolizable energy per kg LW0.62 in the maintenance periods and 980 in the growth periods were derived as maintenance requirement of metabolizable energy. These values for maintenance requirement are by 50% higher than those in previous experiments of our work team. In contrast to expectations, energy maintenance requirement did not grow due to the increase of the protein content of the rations. The utilization of metabolizable energy for retention was 73% for rations with a normal protein content and 66% for those with a high protein content. The partial utilization of metabolizable energy for fat retention was ascertained as 83% and as 49% for protein retention by means of multiply regressive evaluation.     

The energy maintenance requirement of growing pigs of different sexes given normal and high protein diets. 3. Experiments in boars

Six fattening boars each, hybrids of line 150(150 X (L X E] received rations with 17 and 45% crude protein. In the live weight range of 36 to 167 kg, 5 periods of growth feeding alternated with 4 periods of maintenance feeding. Compared with maintenance level the nutrition level of 2.7 did not have an influence on digestibility. Nitrogen retention was only insignificantly influenced by the level of protein supply. The maintenance requirement of the animals used was by 50% higher than in previous experiments made by our work team. On average it amounted to 1,017 KJ metabolizable energy per kg LW0.62, i.e. to 1,063 for those animals fed with rations containing 17% crude protein and to 986 for those animals receiving 45% crude protein in their rations. The utilization of metabolizable energy for energy retention amounted to 75% for rations with 17% crude protein and to 70% for rations with 45% crude protein. The partial utilization of metabolizable energy for fat retention was ascertained as 90% and for protein retention as 53% by means of multiply regressive assessment.     

Joint research on the precise determination of the energy and protein requirements of fattening pigs. 5. The effect of the crude protein concentration in the isocaloric diet on the fattening performance of swine of the Bulgarian Landrace

Live weight development and feed expenditure on 3 levels of crude protein supply and with isocaloric rations were investigated in scientific feeding experiments with 7 castrated male pigs each of the Bulgarian land race in the live weight range between 30 and 100 kg with a subdivision at 60 kg. The crude protein concentrations in the rations for the 3 groups were 17%, 15% and 13% in the first fattening period and 15% 13% and 11% in the second fattening period. In the two fattening periods the digestibility of the feed mixtures used was ascertained in experiments. The daily live weight gain in the three groups over the whole fattening period reached a high level of performance (836 g, 778 g and 757 g). The feed expenditure values were 3.3, 3.7 and 3.7 kg mixed feed (88% dry matter) per kg live weight gain. The highest protein supply resulted in the best weight gain performance and the lowest feed expenditure.     

The energy maintenance requirement of growing pigs of different sexes given normal and high protein diets. 1. Experiments in castrates

Energy retention was measured alternately at 12 barrows, fattening hybrids of line 150 (150 X (L X E], at maintenance level (4 periods) and growth feeding (5 periods) in the live weight range between 32 and 134 kg, 6 animals each received rations with 17 and 45% crude protein resp. during the complete experimental period. The nutrition level did not have a significant influence on the digestibility level of the feed. The experiments carried out at maintenance level showed that the maintenance requirement of metabolizable energy in the experiments with 17% crude protein in the ration was 941, in the experiments with 45% crude protein in the ration 913kJ ME/kg LW0.62 and on average 927 kJ ME/kg LW0.62. Including the experiments with growth feeding one can conclude from a regression analysis, largely in agreement with the measured values, that 955 kJ ME/kg LW0.62 is the energy maintenance requirement. These values of maintenance requirement are by 50% higher than those derived from previous measurings. In contrast to expectations, the increase of protein concentration in the ration did not result in a higher energy maintenance requirement. The utilization of metabolizable energy for retention amounted to 74% for rations with a normal protein content and to 65% for those with a high protein content. The multiply regressive evaluation showed a utilization of metabolizable energy for fat retention of 79% and for protein retention of 53%.     

The energy requirement of heifers. 4. Comparison of the digestibility and rumen physiologic parameters in heifers and full-grown sheep

In 159 comparative studies with fully grown sheep and heifers of the digestibility and of rumen physiologic values at a variation of the feed ration in the crude fibre content between 112 and 318 g, in the crude protein content between 94 and 194 g and in the content of nitrogen free extractive between 484 and 641 g/kg DM is provided that the digestibility of energy in heifers was, on average, 4 digestibility units lower than in sheep. The corresponding values for the digestibility of crude protein and crude fibre are 12 and 3.5 digestibility units. Due to the lower methane energy excretion of the heifers the difference at the level of metabolizable energy is reduced to 1.5% of the gross energy. The level of the differences in digestibility is influenced by the development of the young cattle and the composition of the rations. In young cattle of the live weight range between 100 and 150 kg the digestibility of the energy is 6-8 units lower than in sheep. A higher crude fibre content in the ration diminishes the difference in the digestibility of energy and the nutrients between the two animal species.     

Joint research on the precise determination of the energy and protein requirements of fattening pigs. 8. The effect of various protein levels on the performance and feed expenditure of fattening pigs

Live weight development and feed expenditure were investigated on 3 levels of protein supply and isocaloric rations in scientific feeding experiments with 10 castrated male pigs each of the genetic origin land race pig X large white fed individually in the live weight range between 30 and 100 kg with a subdivision at 60 kg. In the air-dried matter the crude protein content of the feed mixtures used in the first fattening period was 17.6; 15.7 and 13.7% resp. and in the second fattening period from 60 kg live weight onwards 14.9; 12.8 and 11.4% resp. for the 3 test groups. In both fattening periods the digestibility of the rations and the N-balance were determined at 3 representative animals from each of the 3 groups. The following average live weight gains were achieved in the 3 test groups: 1st fattening period: 662; 592 and 539 g resp.; 2nd X fattening period: 709; 676 and 644 g resp. Feed expenditure over the complete fattening period was 4.2; 4.5 and 5.2 kg air-dried matter per kg live weight gain. The highest protein supply resulted in the best live weight gain performance and the lowest expenditure.     

ORIGINAL ARTICLE: Impact of feeding level on digestibility of a haylage‐only diet in Icelandic horses

Eight mature Icelandic geldings were used in an experiment arranged as a change‐over design to evaluate the effect of feeding level on the digestibility of a high‐energy haylage‐only diet. The horses were fed a low feeding level 10.7 g dry matter (DM)/kg body weight (BW) (maintenance) and a high feeding level 18.1 g DM/kg BW (1.5 × maintenance) during two 23 days experimental periods. Total collection of faeces was performed for 6 days at the end of each period to determine the coefficient of total tract apparent digestibility (CTTAD). The CTTAD for DM, organic matter, neutral detergent fibre (NDF), acid detergent fibre and energy was higher in horses fed at the low level of feed intake, while feeding level did not affect the CTTAD of crude protein. The largest difference in CTTAD between feeding levels was found for NDF. The content (/kg DM) of digestible energy in the haylage was 11.3 MJ at the low level of feed intake and 10.6 MJ at the high level of feed intake. It can be concluded that feeding level has a large impact on the digestibility and energy value of early cut haylage in Icelandic horses.     

Joint research on the precise determination of the energy and protein requirements of fattening pigs. 2. Energy and nitrogen metabolism of fattening hybrids in the fattening range of 30 to 120 kg

In 3 experiments a total of 242 total metabolism experiments with ad libitum feeding (experiment 1), 75% (experiment 2) and 62% (experiment 3) of the energy level of the 1st experiment and approximately equal protein and amino acid doses in experiments 1-3 were carried out with 8 castrated male fattening hybrids each (large white X land race pig) X line 150) in the live weight range between 30 and 120 kg. On average, feed intake over the whole live weight range was 2.24; 1.79 and 1.50 kg/animal and day, the corresponding daily live weight gain was 729, 533 and 396 g. With regard to the digestibility of the energy and the nutrients and the metabolisable energy in % of the gross energy there was no relation to the development of the animals. The intake of metabolisable energy per kg live weight decreased with ad libitum feeding and with the advancing development at the end of the experiment in contrast to the beginning of the experiment to 53%, energy retention to 56%. The utilisation of metabolisable energy for body energy retention, taking account of a maintenance requirement of 450 kJ/kg live weight 0,62 on the average of the 3 experiments was 68.4 +/- 1.9, 70.3 +/- 2.0 and 64.3 +/- 2.6%. Energy retention in experiments 1 to 3 amounted to 8.6, 6.8 and 5.3 MJ at the beginning and to 18.1, 12.2 and 8.0 MJ per animal and day at the end of the experiment. Protein energy retention of the pigs (live weight 40 kg) was 26% of the total energy retention in experiments 1 and 2 and 49% in experiment 3. In experiments 1 and 3 protein retention decreased to 15% of the total energy retention, in experiment 2 protein retention remained constantly at 22% between 60 and 110 kg live weight and then decreased to 18%. Consequently, the N-balances were 23-16 g, 16-20 g and 16-9 g/animal and day. The chemical composition of the carcasses was strongly influenced by the level of nutrition. At the beginning of the experiment the protein content averaged between 49 and 57% and the total fat content between 31 and 38% of the dry matter. At the end of the experiment the carcasses of the animals from experiments 1-3 had crude protein contents of 28, 33 and 42% and total fat contents of 66, 61 and 50% of the dry matter.     

Joint research on the precise determination of the energy and protein requirements of fattening pigs. 7. The effect of various energy levels on the performance and feed expenditure of fattening pigs

Scientific feeding experiments were carried out with 7 male castrated pigs of the genetic origin land race pig X large white with the test animals fed individually and the rations containing approximately the same amounts of protein, amino acids, minerals and vitamins but varied amounts of energy. Energy intake was adjusted to three levels: 100%, 85% and 70% of semi-ad-libitum intake (group 1 = 100%). With regard to protein supply there was a subdivision into 30-60 and 60-100 kg live weight. In addition to this, the digestibility of the feed mixture used and the N-balance were determined in both fattening periods. Having reached 100 kg live weight, the animals were slaughtered and a number of slaughtering parameters was determined. The average daily live weight gain in the three test groups was 749, 664 and 540 g over the whole fattening period. The feed expenditure was 3.7, 3.9 and 4.3 kg mixed feed per kg live weight gain so that, with regard to live weight performance and feed expenditure the group with the highest energy supply showed the best results. The level of energy supply had a remarkable influence on the composition of weight gain; thus the amount of fat in the carcass of the animals of groups 3 was by 1.8 kg and 2.5 kg resp. lower than of the animals in groups 2 and 1.     

Urea utilization of growing lambs. 2. Growth experiments

In two growth experiments with 30 lambs per group the influence of urea (1-2% of the ration) and straw (20-30% of the ration) on the performance was studied under conditions of intensive fattening. The content of native crude protein in the rations varied between 10.1 and 18.4% of the DM. In experiment 1 the lambs of the two groups which received mixed feed for fattening lambs without urea on average consumed with 1.02 and 1.11 kg DM resp., 696 and 757 EFUcattle resp. and 173 and 189 g crude protein resp. per animal and day. The groups with wheat or barley and urea consumed 1.06 and 0.96 kg DM resp., 714 and 627 EFUcattle resp. and 209 and 155 g crude protein resp. Their weight gain of 247 g/animal and day was 24% and that of 230 g resp. 26% higher than that in the control groups without urea. The lowest dry matter intake (0.91 and 0.82 kg resp.) was shown by the animals of the groups which received wheat or barley without urea. In the second experiment the control group achieved an average daily weight gain of 327 g at an expenditure of 2.24 kEFUcattle/kg weight gain. Despite a partly higher dry matter intake, the daily EFUcattle intake was between 12.2 and 24.5% lower in the straw groups and energy expenditure increased between 12.0 and 27.8%. Urea supplements of between 1 and 2% improved dry matter, EFUcattle and crude protein intake and thus weight gain.     

Protein and amino acid metabolism in the digestive tract growing young bulls. 1. Flow of bacterial raw protein in the duodenum determined by 2,6-diaminopimelic acid as a marker

The influence of the composition of the rations on the content of diamino pimelic acid (DAP) and N in the bacteria dry matter and on the flow of bacteria crude protein into the duodenum, determined with DAP as marker, was determined on the basis of experimental investigations with young bulls provided with duodenal cannulae and with 28 different rations whose details are described. At a production level corresponding to dry matter intake and a variation range of the crude fibre content of between 11.3 and 29.1% in the DM, a content of N-free extractives between 50.9 and 77.4% in the DM, a content of soluble carbohydrates ibetween 5.3 and 6.4% in the DM, a crude protein content of between 6.4 and 17.1% in the DM and a pure protein content of between 4.9 and 15.5% in the DM, the DAP content of the bacteria DM amounts the 0.350 g 100 g DM +/- 0.090 the N-content of the bacteria DM amounts to 7.37 +/- 1.08 g/100 g DM, there are no relations between DAP- and N-content in the bacteria DM and the content of the individual carbohydrate fractions of the ration, there are positive relations between DAP- and N-content of the bacteria DM, the flow of bacterial crude protein into the duodenum amounts to 133 +/- 14 g/kg truly fermentable organic matter or 130 +/- 14 g/kg apparently digestible organic matter, there is a negative relation between bacteria crude protein at the duodenum (BCPD)/kg truly fermentable organic matter and the crude fibre content of the ration, there is a positive relation between BCPD/kg truly fermentable organic matter and N-free extractives and soluble carbohydrate content as well as the digestibility of the organic matter of the ration, there is no specific influence of the flow rate (kg digesta/kg intake of org. matter) or the dilution rate (g bacteriafree org. matter D/kg LW075/b) on BCPD/kg truly fermentable org. matter, there is a dependence of BCPD/kg truly fermentable org. matter on crude protein concentration in the ration in the concentration range of 6.4-9.0% crude protein in the ration (provided endogenous CP equivalents are used).     

The energetic utilization of rations with steamed potatoes in growing swine]

The energetic utilization of rations with steamed potatoes (40 and 50% of DM of ration) was measured in 8 growing pigs, live weight 30-70 kg by means of respiration experimental techniques. The experiments were carried out using the difference method (3 periods feeding basal diet and 3 periods feeding basal diet plus potatoes). The digestibility of energy of the steamed potatoes amounted to 94%, that of organic substances 96% and that of crude protein 77%. The metabolizable energy amounted to 16.1 and the energy deposition to 12.0 MJ/kg DM of steamed potatoes, 74.5% utilization respectively. The results in growing pigs are very similar to the results in adult pigs.     

Nutritional physiology effect of dietary fats in the diet of growing pigs. 1. Effect of an isocaloric exchange of carbohydrate energy compared with fat energy on protein retention, in vitro synthesis of fat from glucose and on several blood parameters in piglets

Three groups of male, castrated piglets of the German Landrace breed, weight range 3-30 kg, were used to study the relation between fattening performance and blood parameters when feeding rations containing different amounts of fat. The fat content of the rations was either 5% (group I), 18% (group II) or 35% (group III). Concomitantly with the increased metabolizable energy (ME) content of the ration the content of digestible protein (DP) was increased and the amount of feed reduced in order to guarantee an equal intake of ME and DP in all three groups. The digestibility of the crude nutrients and protein retention of the subjects were determined in nine subsequent trials each lasting 7 days. At a body weight of 27 kg the blood concentrations of insulin, glucose, free fatty acids, neutral lipids and cholesterol were determined at different times after feeding. In addition, an oral glucose tolerance test was made and the in-vitro synthesis of fat from glucose was measured. The apparent digestibility of fat amounted, unexpectedly, to approximately 94% on the high rat rations II and III. In all groups a significant positive relation between body weight and digestibility of the fat was determined. Despite equal daily intakes of ME in all groups, in group III daily weight gain and protein retention were 7% (p less than 0.01) and 4% (p less than 0.01) higher than in group I, respectively. Blood urea levels of group III were 67% (p less than 0.01) lower than in group I. The mean daily nitrogen retention of the three groups rose gradually from 4 g at a body weight of 5 kg to 16-17 g at a body weight of 25 kg. The feed conversion of group I was lower by 22 and 36% as compared to groups II and III, respectively. Highly significant differences were observed among either groups (p less than 0.01). It has been calculated that in group III the consumption of ME/kg weight gain was about 8% (p less than 0.05) lower than in the two other groups. According to the increased fat percentage of the rations, body protein content diminished from 17,1% in group I to 16,5 and 16% in groups II and III, respectively. Only the difference between groups I and III proved to be significant (p less than 0.05). In group I feed intake resulted in an increase in the insulin level by 55% (p less than 0.05) whereas glucose did not change significantly.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effect of the starch sources barley, corn, potatoes and their ration fractions on the nutrient digestibility and energy utilization in ruminants. 1. Comparative studies of nutrient digestibility in cattle and sheep]

Rations with energy parts of 50, 25 and 10% from barley, maize and potatoes were investigated comparatively by means of total metabolism experiments with oxen with a view to arriving at a more precise estimation equation of net energy fat for cattle. Parallel to the investigations with oxen the energy and nutrients digestibility of the rations in wethers was measured. The crude fibre content of the rations ranged from 166 to 271 g and the starch content from 69 to 330 g/kg DM. The daily starch intake of the oxen ranged from 575 to 2739 g on nutrition level (NL) 1.7 and from 365 to 1804 g on NL 1.1. The energy digestibility of the rations in oxen with energy parts of 50% barley, maize and potatoes was on average 73.5, 73.9 and 75.3%, of the rations with energy parts of 25% on average 72.2, 71.6 and 72.4% and of the rations with energy parts of 10% on average 68.8, 69.5 and 69.8%. The digestibility of energy and nutrients in cattle and sheep was in good agreement excepted crude protein and crude fat; these were digested 4-5%-units lower from cattle than from sheep. The increase of the nutrition level by one unit lowered the digestibility of rations with energy parts of 50 and 25% from concentrates in cattle about 3-6 units and of rations with energy parts of 10% from concentrates about one %-unit. Information about rumen physiological data is given comparatively between cattle and sheep.     

Physiologic and nutritional studies in pigs with ileorectal anastomoses. 3. Nitrogen retention and utilization following energy an electrolyte supplementation

In order to guarantee an equally good development of ileorectostomized pigs (IRA) used for the determination of precaecal protein digestibility and the absorption of amino acids as for intact animals (INT), the supplementation of their rations with easily soluble carbohydrates and minerals is necessary. The effects of these supplements on live weight development, nitrogen balance and N utilization level were the subject of the assessment of 21 rations with 129 and 117 balance measuring resp. with growing IRA and INT pigs. Without any supplementation of the rations the N balances of the IRA pigs showed significantly lower and partly negative N balances and N utilization levels in comparison to the INT pigs. The combined supplement of easily soluble carbohydrates (100 g/kg DM intake) and 300 ... 400 ml electrolyte solution per day (approximately 1 ... 1.3 g additional Na) resulted in N balances almost equal to those of INT pigs. The supplement of both electrolyte solution and NaHCO3 (approximately 2 g Na per animal and day additionally) to a barley + lysine ration resulted in a significant increase of the N balance and N utilization in IRA pigs of a live weight between 120 and 140 kg in contrast to the control period. A supplement of carbohydrates to a ration consisting of barley + fish meal + grass meal and electrolyte supplements of 400 ml per animal and day only resulted in significantly higher N balances and N utilization levels in the live weight range up to 70 kg in comparison to the control periods, which then corresponded to those of INT pigs. There was no essential influence of carbohydrate supplementations on pigs of more than 70 kg live weight. The postileal digestibility of the crude carbohydrates (CC) of 14 rations calculated from the difference between total digestibility (faecal analysis) and precaecal digestibility (analysis of the ileal chyme of IRA pigs) showed that between 40 and 100 g (70 g on average) out of the 780 g CC per kg DM consumed disappear in the large intestine. These studies show that in the testing of concentrates and mixed feed rations the supplementation of 100 g easily soluble carbohydrates/kg DM intake should be sufficient to guarantee a normal development of IRA pigs. In addition, an oral supply of 1 to 2 g sodium in the form of electrolyte solution exceeding the requirement of INT pigs is necessary as this supplementation significantly improves the N retention of IRA pigs even heavier than 100 kg.     

Studies on the evaluation of feed protein for ruminants. 1. Passage of nitrogen fractions to the duodenum of dairy cows fed different protein and carbohydrate sources

The duodenal passages of non-ammonia nitrogen (NAN), amino acid N (AA-N) and microbial N (MN) were measured in seven duodenal fistulated dairy cows (6130 kg FCM/305 d) during lactation receiving 30 different rations similar to those used in dairy practice. The rations consisted of roughage (protein-rich silages, hay) and concentrate mixture (corn, barley, oat) in a ratio of 60:40 on a DM basis or roughage/concentrate mixture/fodder beets in the proportions 60:20:20 or 60:0:40 respectively. N supplements consisted of soya bean meal and peas meal (untreated or treated with formaldehyde in each case), rapeseed meal, fish meal and urea. DM intake varied between 9.6 and 19.1 kg/d, the crude fibre content between 166 and 270 g/kg DM, the crude protein (CP) content between 111 and 184 g/kg DM, the AA content (N basis) of the CP between 51 and 82%, the unfermentable CP content of the CP between 23 and 49% and the organic matter digestibility between 70 and 79%. The duodenal passage of NAN was 24.2 +/- 2.7 g/kg DM intake, 34.9 +/- 4.1 g/kg apparently digestible organic matter (in total tract, DOM), 43.3 +/- 5.5 g/kg apparently digestible carbohydrates or 4.2 +/- 0.5 g/MJ net energy fat, (y +/- s, n = 90). The value measured for AA-N was 16.8 +/- 2.9 g/kg DM intake, and that for RNA-labelled microbial CP was 146 +/- 26 g/kg DOM. NAN passage (g/kg DM intake) correlated more closely with the duodenal digesta flow rate (DFR) (kg digesta/kg DM intake) as an intrinsic animal factor (r = 0.78) and with the rumen content dilution rate (RDR) (passage of microbial-free organic matter at duodenum/kg BW0.75.h) as a ration dependent factor (r = 0.64) than with the UDP fraction (% of ration CP) (r = 0.50) or other ration parameters. It was concluded that the specific effect of protein concentrates in mixed rations on duodenal NAN yields in lactating dairy cows is lower than hitherto assumed. The duodenal NAN yield of a single feedstuff or ration (g/kg DM) in cows is dependent on animal and feeding factors. The DFR could represents a suitable target for breeding activities.     

The energy metabolism of swine at a feed level of "live weight equilibrium"

10 castrated pigs each of a live weight (LW) of 35 kg and 115 kg were fed over 28 and 40 days resp. in a way that a live weight equilibrium was achieved. The pigs were kept individually and at a low mobility on perforated floors of zinc-plated sheet iron at an air temperature of 19 degrees C. The weighing 35 kg received 668 kJ ME/kg LW 0.75 per day and one half of the animals weighing 115 kg 635 kJ ME/kg LW 0.75 in a diet consisting of barley and bran. The other half of the animals weighing 115 kg received 514 kJ ME/kg LW 0.75 per day in a ration consisting barley, bran and dried skim milk. The crude protein content of the rations was 12.6 and 17.1% resp. of the DM, the crude fibre content amounted to 8-10% of the DM. Energy excretion in faeces and urine was calorimetrically measured. Up to the end of the experiment LW and the weight of the empty body (without ingesta) remained unchanged. For the measuring of energy retention, 4-5 zero animals each were analysed before the experiments. The pigs weighing 35 kg showed a daily loss of 39 g fat in the course of the 40-day experiment. The calculation of the energy balance showed that an intake of 790 kJ ME/kg LW 0.75 was necessary. This maintenance requirement, rather high in comparison with values from literature, can be explained with the emission of body heat on sheet iron floors and a crude fibre content of 9% in the rations. The pigs of the two groups of 115 kg LW were at an energy equilibrium at both nutrition levels. The lower maintenance requirement of the group fed with dried skim milk cannot exclusively be explained by the higher energetic utilization of the milk protein in the ration. The reason should be the more advanced age of the animals of the milk group. Although they had nearly the same live weight, their empty bodies contained 41% fat, the pigs of the barley/bran group, however, only 34%, both before and after the experiment.     

Protein and amino acid metabolism in the gastrointestinal tract of young bulls. 3. Flow of NH3-free raw protein into the duodenum

The amount of NH3-free crude protein getting into the duodenum corrected by the endogenous crude protein quota was determined on the basis of 28 differently composed rations for growing bulls in the live weight range of 140-460 kg provided with duodenal re-entrant cannulae. The experimental results were generalized by means of regression analysis and can be summarized as follows: The amount of NH3-free crude protein getting into the duodenum can partially be calculated with the regression equation (Formula: see text) resp. NH3-free crude protein D = 155 app. dig. org. matter + 0.262 pure protein +/- 42. The remaining dispersion amounts to +/- 6% of the mean value. The coincidence between the values calculated with these equations and those measured experimentally is very good. There is an interaction between the pure protein of feed getting into the duodenum in % of pure protein intake (y) and the bacteria crude protein D/kg app. dig. org. matter (x) characterized by the equation y = 116.8-0.52 x +/- 12.9. The amount of NH3-free crude protein duod. is not influenced by the flow rate (kg digesta/kg intake of org. matter) and not by the "dilution rate' (g bacteria free org. matter duod./kg live weight 0.75/h) either at a DM intake adequate to the production level. Apart from the partial estimation of the NH3-free crude protein duod. a evaluation based on the crude protein and pure protein concentration in app. dig. org. matter of the ration is possible.     

The digestibility of crude nutrients in horses. 2. Comparative studies on the digestive capacity of a thoroughbred horse, pony and wether

The digestibility of the crude nutrients of 6 rations on the basis of oat, hay and wheat straw (in one case a straw-concentrate mixture as sole feed) was compared at a nutrition level of 1.0 and 1.3 resp. with adult geldings of the species "Noble Crossbreed", adult pony geldings and wethers The energy concentration of the rations varied between 424 and 585 EFUcattle/kg DM, the crude fibre content between 17 and 25% of the DM. In the studied field, a good agreement between horse and pony could be ascertained as to the digestibility of the organic matter and NFE. There are partly considerable differences between the apparent digestibility of crude protein and crude fibre. The differences in the digestibility of crude fibre between horse and sheep increase with a growing crude fibre content. The differences of the apparent digestibility between horse and pony on the one hand and sheep on the other were highly significant in all cases.