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 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 preservation requirements of growing pigs of different sexes fed normal and high protein diets. 5. Comparison with the results obtained from castrated pigs, sows and boars

In one experiment each with castrated pigs, sows and boars (hybrid pigs of line 150), two groups of six animals received rations containing 17 and 45% crude protein resp. over the complete test period from 35 to 130 kg (castrated pigs), 150 kg (sows), 170 kg live weight (boars) and passed alternatively through a total of 60 metabolism periods on growth and 48 on maintenance level. There were significant differences between the 3 categories of animals with regard to energy maintenance requirement in the relation of 100:105:110 for castrated pigs less than sows less than boars. In contrast to the estimated values derived from previous studies for energetic maintenance requirement of 650 kJ/kg LW0.62.d the measured values for all 3 animal categories are by approximately 50% higher. The protein content did not have an influence on the maintenance requirement of metabolizable energy of the animals. The utilization of metabolizable energy of the two rations for body energy retention corresponds to the expectations with regard to its dependence on nutrients. The requirement of metabolizable energy for protein and fat retention is 1.7:1.0. The energy content of the weight gain of boars was, on average, 85% of that of castrated pigs and sows. The studies of blood parameters did not show any deviations in the parameters tested.     

Energy requirements of pregnant and lactating sows

The energy requirement of pregnant and lactating sows is derived on the basis of extensive experimental studies of the energy metabolism (indirect calorimetry, slaughtering) according to the factorial method. For the first reproduction cycle (RC) 0.41 MJ metabolizable energy (ME) or 0.29 MJ net energy fat, pig (NEFpig) resp. were necessary for energy maintenance requirement for pregnant and lactating sows and, depending on age, 0.44 MJ ME or 0.31 MJNEFpig in the second or third RC and 0.47 MJ ME/kg LW0.75.d or 0.33 MJ NEFpig/kg LW0.75.d in the 4th-8th RC. A linear increase of up to 6% of the energy requirement caused by pregnancy between the 85th and 115th day of pregnancy is taken into consideration. Energy requirement per 1 MJ retention both in pregnancy and lactation is 1.45 MJ ME or 1.03 MJ NEFpig, per 1 MJ milk yield it is 1.33 MJ ME or 0.91 MJ NEFpig. 1 MJ body energy for milk yield corresponds to 1.20 MJ ME or 0.82 MJ NEFpig. Equations describing energy retention in the products of conception, uterus and udder are established as well as equations characterizing the connections between live weight gain or loss and energy content of the gain or loss.     

Energy requirements of young female cattle. 6. Energy requirements

Results taken from 6 experiments with young female cattle comprising 477 metabolism periods served the derivation of the animals energy requirement in the development range greater than 125 kg live weight according to the factorial method. The energy requirement per kg LW0.75 and day, calculated from metabolism data, was independent of the stage of development and the intensity of feeding. It averaged 455 +/- 66 kJ metabolizable energy/kg LW0.75.d and 250 +/- 37 kJ NEFcattle/kg LW0.75.d respectively. The partial energy requirement for live weight gain, expressed in net energy fat, was equivalent to the energy content of the live weight gain. Energy retention and thus energy requirement per kg live weight gain increased with the live weight and reached a maximum of 26 MJ. Energy retention per kg live weight gain largely depended on the intensity of feeding and the stage of gravidity. Restrictive energy supply and progressing gravidity decreased energy content in the weight gain. The influences mentioned were taken into consideration on the derivation of the partial requirement for live weight gain. Equations were developed for the estimation of the energy requirement of young female cattle, which can be applied to both gravid and non-gravid cattle.     

Energy metabolism of growing broilers in relation to the environmental temperature

7 experiments with 6 chickens each (origin Tetra B) in the live weight range between greater than 100 and less than 300 g and up to 1800 g were carried out at environmental temperatures (ET) of 35, 30, 25 (2 experiments) 20 (2 experiments) and 15 degrees C. In the course of each experiment the chickens alternatively received feed mixtures containing 20 and 40% crude protein (3 animals/variant) for maintenance and weight gain (semi ad libitum). Energy metabolism was measured according to indirect calorimetry over a total of 645 metabolism periods. In the temperature range studied there was no compensation between thermoregulatory heat and heat from other metabolic processes. The partial utilization of metabolizable energy for energy retention in the body was independent of ET and remained in the limits between 71 and 73%. Energy utilization was dependent on the protein content of the feed. It decreased from 75 to 69% with the increase of the protein content from 20 to 40%. Energy requirement for protein retention varied between 1.67 and 1.89 kJ metabolizable energy/kJ and was independent of ET. Energy requirement (metabolizable energy) for the maintenance of the energy balance was independent of the protein content of the feed. It increased from 433 kJ/kg LW0.75.d at 35 degrees C to 693 kJ/kg LW0.75.d at 15 degrees C ET. The relationship between heat production and ET is parabolic. The thermoneutral temperature decreased from 35 to 25 degrees C in the course of development. In the live weight range of 300-500 g thermoregulatory heat production had its maximum with 19 kJ/kg LW0.75.d.K and decreased in the further development to 10-13 kJ/kg LW0.75.d.K.     

The energy metabolism of growing swine in the liveweight range of 10-50 kg. I. Study design, feed intake and digestibility

Studies of the energy metabolism at maintenance and growth levels after the feeding of rations with a crude protein content of 17-24% and 44-47% resp. were carried out with hybrid pigs of line 150 in the live weight range between 10 and approximately 50 kg. This paper gives information on the methods and the outlay of the experiment and presents results concerning feed intake, live weight development and digestibility. Feed intake increased on average with growing live weight by 30-35 g DM/kg live weight. Feed conversion ranged from 1.2 to 1.8 kg DM/kg live weight gain in the first period and from 2.3 to 3.2 kg DM/kg live weight gain in the last period. The digestibility of the energy in the rations with a crude protein content of between 17 and 24% averaged 80% and that of the rations with a crude protein content of 44-47% averaged 86%. In the course of ontogenetic development the digestibility increased up to about 30 kg LW. The influence of the nutritional level on the level of digestibility was unequal in the experiments. In one experiment a decrease (1% unit) and in two experiments an increase (1-3% units) of the digestibility after the feeding of growth level in contrast to maintenance level could be observed. The change of rations with a varying protein content did not result in an influence on the digestibility level in comparison with the constant feeding of one ration.     

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.     

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.     

Performance and body composition of fatteningpigs of two strains during protein deficiency and subsequent realimentation

The influence of protein restriction and subsequent realimentation on protein and lipid depositionas studied. Between 28 kg and 65 kg live weight (LW ), entire male pigs of two strains (a commercial and a sire strain) were given diets either deficient or adequate in protein content. From 65 to 105 kg LW all pigs were fed a protein-adequate ration. Animals were slaughtered and dissected at start, 65 and 105 kg LW. Body composition and deposition rates of protein, lipid, lean and fatty tissue for both the restriction period (28–65 kg LW) and the realimentation period (65–105 kg LW) were calculated. Protein restriction reduced feed intake (28%), live weight gain (60%), and rate of protein (75%) and lipid deposition (15%) between 28 and 65 kg live weight. A165 kg, restricted animals had twice as much lipid and were 60 days older than controls. During realimentation, previously restricted pigs (compared to controls) had slightly (7%) reduced feed intake and 15% increased weight gain and efficiency. Protein deposition rate beyond 65 kg LW was increased by 13% and ratio of lipid to protein deposition was decreased from 1.69 to 1.23. At 105 kg, the previously restricted pigs still were older and fatter than controls, so compensation was not complete. Strains of pigs responded similarly to both restriction and realimentation. Dissection at 105 kg LW was not sensitive enough to show the effects revealed by chemical analysis. The experiment revealed that nutritional history may influence the relation between lipid deposition rate and protein deposition rate.     

Energy metabolism of growing rats in relation to the environmental temperature

8 experiments were carried out with 9 albino rats each (Wistar line, bred at the institute) in the live weight range between 70 and 200 g and at environmental temperatures (ET) of 34, 32, 30, 28, 26, 24, 22 and 20 degrees C. In the course of each individual experiment the rats were alternatively fed for maintenance and weight gain (semi ad libitum) with feed mixtures containing 10, 25 and 40% crude protein (3 animals/variant). Energy metabolism was measured according to the method of indirect calorimetry over a total of 780 metabolism periods. In the temperature range studied there was no compensation between thermoregulatory heat and heat from other processes of the metabolism. The partial utilization of metabolizable energy for energy retention in the body was independent of ET and ranged between 73 and 80% for the 7 experiments with ET between 32 and 20 degrees C. Energy utilization depended on the protein content of the feed and decreased from 81 to 79 or 73 resp. when the protein content increased from 10 to 25% or to 40% resp. Energy requirement for protein retention varied between 1.61 and 2.09 kJ metabolizable energy/kJ and was independent of ET. Energy maintenance requirement (measured at 28, 30 and 32 degrees C) increased with the growing protein content from 415 to 439 and 447 kJ/kg LW0.75.d resp. (regression analysis) and from 411 to 420 and 432 kJ/kg LW0.75.d (measuring at maintenance level). The relative weight gain with the increased protein content of the feed largely corresponds to the expected values according to the efficiency of ATP synthesis in the oxidative degradation of nutrients. The relationship between heat production and ET is parabolic. In the live weight range studied the average thermoneutral temperature (TNT) was 32 degrees C. It decreased during the course of development from 34 to 30 degrees C. TNT decreased with the growing protein content of the feed. Thermoregulatory heat production depended on both environmental temperature and the stage of development. Its average value in the development range studied decreased with an increase of the environmental temperature by 2 K each, starting from 20 degrees C and rising to 32 degrees C, in the following linear sequence: 23.3, 21.0, 16.8, 12.5, 8.3, 4.0 and 0.3 kJ/kg LW0.75.d.K.     

Studies on nitrogen retention in growing pigs

Nitrogen retention (RN) was measured in 60 barrows of Danish Landrace and a total of 470 balance periods was carried out during the growth period from 20 to 85 kg live weight. In the first serie (Expt A) six different feed compounds of high biological value (HBV) were fed to 48 barrows, while in the second serie (Expt B) 12 barrows were measured on feed compounds of HBV or low biological value (LBV). Three different levels of gross energy were used in Expt B. Individual differences of 10-20% in the pigs capability for nitrogen retention were observed. Nitrogen retention increased from 12 to 21 g N/d on the HBV-compounds and was not influenced by increasing nitrogen or energy intake. Nitrogen retention was curvilinear in relation to metabolic live weight (kg0.75) in both series. A parabolic function on kg0.75 gave the best fit to the data with the following regression equations: Expt A + B: RN, g/d = 1.48 LW, kg0.75 - 0.027 LW, kg1.50 (HBV) Maximum = 20.5 g RN/d at 84 kg LW Expt B: RN, g/d = 1.03 LW, kg0.75 - 0.013 LW, kg1.50 (LBV) Maximum = 20.4 g RN/d at 133 kg LW     

The net energy value of crude (catabolized) protein for growth in pigsValeur énergétique nette des matières grasses pour la croissance du porcDer nettoenergiewert von rohprotein (katabolisiert) für das wachstum bei schweinen

An experiment was performed with 36 growing pigs of Danish Landrace, to study the influence of digestible crude protein on the energy excretion with the urine and on the efficiency of utilization of metabolizable energy.The pigs (3 litters of females and 3 litters of male castrates) were distributed on six dietary treatments on a within-litter basis, taking into account the live weight of the pigs. The daily intake of the different diets was adjusted in such a way that the daily gain in the different treatment groups was almost identical through the entire experimental period from 20–90 kg.Three digestibility and nitrogen balance experiments were performed with each pig. At approximately 90 kg live weight the pigs were killed, dissected, ground, mixed and chemically analysed. The energy loss in urine increased by 4.9 kJ and the efficiency of utilization of metabolizable energy was decreased by approximately 6.6 kJ/g of catabolized protein.Digestibility experiments with ileo-caecal cannulated pigs indicated that the proportion of the digested energy disappearing in the caecum-colon increased with increasing dietary concentration of crude protein.     

Effect of a bran diet on the total passage rate and tract measurements in weanling swine

88 piglets of a live weight of 9.5 kg were fed rations with 0, 2.1, 3.1 or 5.5% crude fibre over a period of 4 weeks in four groups, during which time the total passage rate per week and the volume of the tract segments on the 42nd and 63rd day of life were determined. After the weaning-conditioned constipation of all animals, the passage rates could be significantly raised from the first keeping week onwards by crude fibre admixtures in the shape of bran and thus reached the customary values of older animals in their fourth week of keeping. Crude fibre admixtures significantly increased the volume of the colon. The recommended content of crude fibre in the piglet starter feed is 5-6% in the shape of bran.     

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.     

Relation between 15N excretion in feces following oral 15N urea administration and blood urea concentration in relation to raw fiber intake in swine

9 pigs of a live weight at the beginning of the experiment of 33 kg received in 3 consecutive series of experiments (3 animals/group) a basic barley ration of 1.0-1.2 kg per animal and day. In groups 1 to 9 the following supplements were given: 1 = without N-supplement, 2 = 10.5 g urea, 3 = 79 g dried skim milk, 4 = 11 g urea, 5 = without N-supplement, 6 = 110 g horse bean coarse meal, 7 = without N-supplement, 8 = 95 g dried skim milk, 9 = 120 g horse bean coarse meal. In groups 1-6 the ration was supplemented with 150-165 g DM partly hydrolysed straw meal per animal and day. After 20 days the animals received a single dosis of 0.5 g/kg0.75 15N-urea (72.1 atom-% 15N-excess) with the morning meal of the first day of the experiment. During the four days of the experiment groups 1-6, due to the straw meal supplement, excreted significantly higher N-amounts than the corresponding groups 7-9. In comparison with the first day of the experiment (1 h after the morning meal) urea concentration in the blood decreased to the following percentage in the sequence 1-9: 64; 65; 77; 54; 64; 73; 82; 88; 84 on the second day of the experiment (1 h before the evening meal. Between the excretion of 15N-excess in faeces (y = mg) during the four days of the experiment and the concentration of urea in the blood (x = mmol/l) there was the following significant negative correlation: y = -40.1 X +340.(ABSTRACT TRUNCATED AT 250 WORDS)     

Energy intake and milk production in mink (Mustela vison)--effect of litter size.

Energy intake and milk production were measured in 12 mink dams raising litters of 3, 6 and 9 kits one to four weeks post partum by means of balance experiments and measurements of milk intake of the kits by the water isotope dilution technique. The dams were fed ad libitum on a conventional wet mink diet (DM: 323 g/kg; CP: 173 g/kg; ME: 4.4 MJ/kg). Milk samples collected from dams with corresponding litter sizes and lactation weeks, and body composition of kits nursed by these dams, were analysed for content of DM, ash, N and fat. The ME and drinking water consumption were higher in dams nursing 9 kits than in dams nursing 3 kits. The N and water balances as well as the live weight of dams were not affected by litter size. Daily milk production was higher in dams nursing 9 kits than in dams nursing 3 kits. The DM, N and fat content of the milk increased during lactation, but were not affected by litter size. Individual kit live weight was higher in litters of 3 than in litters of 6 and 9 kits four weeks post partum. The DM and fat content of the kits were lowest in kits from litters of 9 kits, whereas these kits had the highest protein content. Daily ME for maintenance of kits and the efficiency of utilisation of ME in milk for body gain were estimated to 356 kJ/kg0.75, kp approximately 0.53 and kf approximately 0.71, respectively. In conclusion, daily milk production increased with increasing litter size, but not in proportion to the number of kits, indicating that milk production limits the growth rate of the young. In the fourth week of lactation, milk production was not different between dams nursing 6 or 9 kits, indicating a maximum capacity.     

Investigation of the feed value of straw

Two groups of four pigs each were fed ad libitum with rations containing 70.7% barley, 7.7% fish meal, 0.7% Sussopan, 0.9% mixed minerals and 20% straw meal. Group 1 received partly hydrolysed straw meal, group 2 untreated straw meal. When those rations were given, weight increase performances of 767 g per animal and day in group 1 and 537 g per animal and day in group 2 were achieved in a preliminary 30-day feeding period. On the basis ofthe weight of the feed remnants, a consumption of 19.7% dry matter of the straw meal (group 1) resp. 18,5% (group 2) of the total intake of dry matter could be ascertained. At an average live weight of 93 kg (group 1) resp. 87.5 kg (group 2) the digestibility of both rations was examined. A significant difference was only found for the crude protein fraction with an apparent digestibility of 74.6% in group 1 and of 79.1% in group 2. Those pigs which received partly hydrolysed straw meal consumed 71.4 g N per animal and day, of which 25,4% were excreted in feces and 32.4% in urine. Those animals which were fed with untreated straw meal consumed 62.9 g N per animals and day of which 20.8% were excreted in feces and 49.7% in urine. The higher N-excretion in feces could also be proved for most amino acids the feeding with partly hydrolysed straw meal. For arginine, serine, glutamic acid, proline, isoleucine and Leucine these differences were significant. Differences concerning N-retention could not be found between the groups. 25% of the organic matter of the partly hydrolysed straw meal, 9.4% of the crude fibre and 44.2% of the N-free extractives were digestible. Of the untreated straw, 12.9% of the organic matter, 5.5% ofthe crude fibres and 21.7% of the N-free extractives were digestible. 193 EFpig were calculated for partly hydrolysed and 105 EFpig for untreated straw meal per kg dry matter. The result of substracting the CaCl2 of the partly hydrolysed straw meal is 205 EFpig per kg dry matter of the straw.     

The net energy value of crude fat for growth in pigsValeur énergt́ique nette des matières grasses pour la croissance du porcDer Nettoenergiewert von Rohfett für das Wachstum bei Schweinen

An experiment with 36 growing pigs of Danish Landrace was performed to study the influence of crude (animal) fat on the digestibility of crude fat and on the efficiency of utilization of metabolizable energy.The pigs (females from 3 litters and male castrates from 3 litters) were distributed on six dietary treatments on a within-litter basis, taking into account the live weight of the pigs. The daily intake of the different diets was regulated in such a way that the daily gain in the different treatment groups was almost identical throughout the entire experimental period from 20–90 kg.Three digestibility and balance experiments were performed with each pig, and at approximately 90 kg live weight the pigs were killed, dissected, ground, mixed and chemically analysed. The digestibility of crude fat increased with increasing concentration of dietary fat and the efficiency of utilization of metabolizable energy was increased by 5.0 kJ g^?1 digestible crude fat.Digestibility experiments with ileo-caecal cannulated pigs showed that the proportion of the digested crude fat and fatty acids disappearing in the caecum—colon decreased with increasing concentration of dietary crude fat, which results in a positive contribution of digestible crude fat to net energy besides its contribution to metabolizable energy.