Utilization of energy for growth in lambs of the breed german merino landsheep

Based on energy deposition and energy intake the utilization of energy for fat and protein deposition and the mean energy utilization for growth as well as the energy requirement for maintenance were estimated in this study. Fifty-four male and 54 female lambs were fed at three feeding levels and slaughtered at various body weights (BW): 18, 30, 45, and 55 kg. Based on the method of the comparative slaughter technique the total body of each animal was analysed. From the data of empty-body gain, fat, protein and energy deposition in the different fattening periods was calculated. The utilization of metabolizable energy for growth and maintenance was estimated by a multiple linear regression model. In this regression model, a utilization of energy for fat deposition of 71% and for protein deposition of 30% was determined (R² = 0.869). The requirement for maintenance was 520 kJ·kg BW ^{? 0.75}·d ^{? 1}. A slightly higher requirement for maintenance was determined for female lambs. The study indicated that the used regression model can be recommended to estimate the utilization of energy and the requirement for maintenance in growing lambs.     

Energy and protein requirements of Santa Ines lambs,a breed of hair sheep

An experiment was carried to evaluate the energy and protein requirements for the growth and maintenance of lambs of different sex classes. In all, 38 hair lambs (13.0±1.49 kg initial BW and 2 months old) were allocated in a factorial design with diet restriction levels (ad libitum, 30% and 60% feed restriction) and sex classes (castrated and non-castrated males). Four animals from each sex class were slaughtered at the beginning of the trial as a reference group to estimate the initial empty BW and body composition. The remaining lambs were weighed weekly to calculate BW gain (BWG), and when the animals fed ad libitum reached an average BW of 30 kg, all of the experimental animals were slaughtered. Before slaughter, fasted BW (FBW) was determined after 18 h without feed and water. Feed restriction induced reductions in body fat and energy concentration, whereas water restriction showed the opposite effect, and the protein concentration was not affected. The increase in BW promoted increases in body fat and energy content, and these increases were greater in castrated lambs, whereas the protein content was similar between classes tending to stabilize. The net energy required for gain (NE_g) and the net protein required for gain (NP_g) were not affected by sex class; therefore, an equation was generated for the combined results of both castrated and non-castrated lambs. The NE_g varied from 1.13 to 2.01 MJ/day for lambs with BW of 15 and 30 kg and BWG of 200 g. The NP_g varied from 24.57 to 16.33 g/day for lambs with BW of 15 and 30 kg and BWG of 200 g. The metabolizable energy efficiency for gain (k_g) was 0.37, and the metabolizable protein efficiency for gain (k_pg) was 0.28. The net energy required for maintenance (NE_m) and the net requirement of protein for maintenance (NP_m) did not differ between castrated and non-castrated lambs, with values of 0.241 MJ/kg FBW^0.75 per day and 1.30 g/kg FBW^0.75 per day, respectively. The metabolizable energy efficiency for maintenance (k_m) was 0.60, and the efficiency of metabolizable protein use for maintenance (k_pm) was 0.57. Nutritional requirements for growth and maintenance did not differ between castrated and non-castrated lambs. This study emphasizes the importance of updating the tables of international committees and of including data obtained from studies with sheep breeds raised in tropical conditions, with the purpose of improving the productive efficiency of the animals     

Estimates of individual factors of the tryptophan requirement based on protein and tryptophan accretion responses to increasing tryptophan supply in broiler chickens 8-21 days of age

Ten diets (196 g CP and 13.0 MJ ME(N)/kg) with graded levels of tryptophan (Trp) between 0.9 and 2.7 g/kg were offered ad libitum to Ross broilers from day 8-21 post-hatch. Each diet was allocated to three pens of ten birds each. In addition to growth and feed conversion, the accretions of protein, Trp, fat, and energy were determined by comparative whole body analyses. A sigmoidal function was fitted to the data. Responses to Trp supply were nonlinear and attained plateau values (y(max)) within the studied range of Trp supply. The Y(max) values estimated for BW gain, whole body protein gain, and Trp gain during the 14 days under study were 615, 104, and 0.87 g/bird, respectively. Based on the response in whole body protein gain, the estimated requirement was 1.9 g Trp/kg of diet or 0.15 g Trp/MJ of MEN. Estimates made from the other response criteria were similar to this value. While the protein concentration in gained BW was unaffected by Trp intake (169 g of protein per kg of gained BW), fat and energy concentrations of gained BW increased with increasing Trp supply, approaching plateau values of 146 g fat and 9.8 MJ energy per kg of gained BW. This is supposed to result from feed intake increasing with Trp supplementation. The Trp concentration in gained whole body protein (0.84 g Trp/ 16 g of gained N) was not significantly affected by Trp intake. As long as Trp intake was the limiting factor, 59% of supplemented Trp was transferred to gained whole body protein. During the 14 days of the study, broilers inevitably lost 87 mg Trp. This is equivalent to a daily loss of 30 mg/kg BW or a maintenance requirement of 52 mg/kg BW per day. Data determined for the individual factors may be used for future modelling of broilers' Trp requirement.     

Estimates of individual factors of the tryptophan requirement based on protein and tryptophan accretion responses to increasing tryptophan supply in broiler chickens 8 – 21 days of age

Ten diets (196?g CP and 13.0 MJ ME_N/kg) with graded levels of tryptophan (Trp) between 0.9 and 2.7?g/kg were offered ad libitum to Ross broilers from day 8?–?21 post-hatch. Each diet was allocated to three pens of ten birds each. In addition to growth and feed conversion, the accretions of protein, Trp, fat, and energy were determined by comparative whole body analyses. A sigmoidal function was fitted to the data. Responses to Trp supply were nonlinear and attained plateau values (y_max) within the studied range of Trp supply. The y_max values estimated for BW gain, whole body protein gain, and Trp gain during the 14 days under study were 615, 104, and 0.87?g/bird, respectively. Based on the response in whole body protein gain, the estimated requirement was 1.9?g Trp/kg of diet or 0.15?g Trp/MJ of ME_N. Estimates made from the other response criteria were similar to this value. While the protein concentration in gained BW was unaffected by Trp intake (169?g of protein per kg of gained BW), fat and energy concentrations of gained BW increased with increasing Trp supply, approaching plateau values of 146?g fat and 9.8 MJ energy per kg of gained BW. This is supposed to result from feed intake increasing with Trp supplementation. The Trp concentration in gained whole body protein (0.84?g Trp/16?g of gained N) was not significantly affected by Trp intake. As long as Trp intake was the limiting factor, 59% of supplemented Trp was transferred to gained whole body protein. During the 14 days of the study, broilers inevitably lost 87?mg Trp. This is equivalent to a daily loss of 30?mg/kg BW or a maintenance requirement of 52?mg/kg BW per day. Data determined for the individual factors may be used for future modelling of broilers' Trp requirement.     

Metabolizable energy requirements for maintenance and growth of Awassi lambs

Twenty four Awassi lambs (mean BW 24.4 kg) were used in a two periods experiment to measure maintenance (zero growth) and growth requirements of metabolizable energy (ME). During the pre-treatment period (period 1, 3 weeks) all lambs were maintained at a constant level of feed intake (2% BW). During the treatment period (period 2, 10 weeks) the lambs were divided into four equal groups and fed different amounts (2, 3, 4 and 5% of BW). Six additional lambs of similar BW and age were killed at the beginning of the experiment to compare final empty body weight (FEBW) with initial body weight (IBW). Twelve lambs, divided into four equal groups were fed the experimental diet in the same amounts as in the growth experiment (period 2) to determine the digestibility of energy.

Energy requirement for maintenance (EM) was measured by both constant weight technique, using data collected during period 1, and regression technique by regressing ME intake on body weight gain (BWG) and empty body weight gain (EBWG). EM measured during the constant weight period (pre-treatment) and overall experimental period (pre-treatment plus treatment periods) were 0.482 and 0.466 MJ of ME per kg M^0.75 per day. Predicted energy requirements for growth (Eg) calculated from equations derived during the treatment period were 0.433, 0.623, 0.782, 0.910 and 1.007 (MJ per kg M^0.75 per day) for the growth rates 50, 100, 150, 200, and 250 (g per day) respectively. It is concluded to be more appropriate to use the values derived during the overall experimental period for maintenance and the overall treatment period for growth as they are most applicable to production situations.     

Histidine maintenance requirement and efficiency of its utilization in young pigs

An experiment was conducted in young pigs (initial BW 10.1 kg) to estimate the maintenance requirement for histidine and its efficiency of utilization for protein accretion using a comparative slaughter technique. Three groups of six pigs each were fed a purified diet supplying 0, 14 or 56 mg histidine per kg BW0.75. Following 21 d of feeding, pigs were killed for whole body compositional analysis. A representative group of six pigs was killed at the beginning of the experiment. Retention of histidine and total N were the main criteria of response. Histidine retention (R2 = 0.73) and N retention (R2 = 0.78) were linear functions of histidine intake (p < 0.001). Histidine requirement for zero histidine retention was 15.5 mg/kg BW0.7, whereas histidine required for zero N retention was 4.1 mg/kg BW0.75. At zero histidine retention, the pigs retained daily 82 mg N/kg BW0.75, presumably due to the degradation of histidine-rich compounds such as haemoglobin and/or carnosine. The slope of the regression line relating histidine retention to N retention indicated that 105 mg of histidine was deposited per gram of total N which was considerably less than the estimated histidine concentration in body protein (179 mg/g N). Based on the slopes of regression equations for histidine and N retention, marginal efficiency of histidine utilization was calculated to be 0.94 and 1.34, respectively.     

Effect of feed intake on heat production and protein and fat deposition in milk-fed veal calves

Energy requirements for veal calves have not been updated recently despite the increased age at slaughter and the predominance of the Prim'Holstein breed in Europe. The objectives of this study were to determine the effects of four feeding levels (FLs) on protein and fat deposition and heat production in milk-fed calves at three stages of fattening and to determine energy requirements of calves. At each stage, 16 Prim'Holstein male calves (mean body weight (BW): 73.4, 151.6 and 237.4 kg) were fed a milk replacer at 79%, 87%, 95% or 103% of a reference FL. Measurements for one stage were conducted over 4 successive weeks in two open-circuit respiration chambers and consisted of a 6-day nitrogen and energy balance followed by a fasting day for estimating fasting heat production (FHP) of the calves. Heat production (HP) measurements were analyzed using a modeling approach to partition it between HP due to physical activity (AHP), feed intake (thermic effect of feeding (TEF)) and FHP. There was no effect of FL and stage on apparent digestibility coefficients, except for a tendency for increased digestibility coefficient of fat as animals got older. The metabolizable energy (ME)/digestible energy (DE) ratio did not depend on FL but decreased (P < 0.01) as animals got older in connection with marked increases in urinary glucose and urea excretion. The AHP and TEF components of HP were not affected by stage or FL and averaged 8.4% and 7.8% of ME intake, respectively. The FHP, expressed per kg BW0.85, increased with increasing FL, suggesting that also ME requirement for maintenance (MEm) may depend on FL. For an average intake of 625 kJ ME/kg BW0.85 per day (95% of the reference FL), FHP was 298 kJ/kg BW0.85 per day. Energy retention as protein and fat increased with increasing FL resulted in higher BW gain. But the rate of increase depended on stage of growth. The slope relating protein deposition to FL was lower in the finishing phase than in the growing phase, while the slope for lipid deposition was greater. Protein and fat contents of BW gain were not affected by FL but increased as animals got older. From these results, the energy requirements of veal calves are proposed according to a new approach, which considers that MEm (expressed per kg BW0.85) depends on ME intake (kJ/kg BW0.85) according to the following relationship: MEm = 197 + 0.25 × ME intake. The corresponding marginal efficiencies of ME utilization for protein and fat deposition are then 82% and 87%, respectively.     

Apportioning protein requirements for maintenance v. growth for blue-breasted quail (Excalfactoria chinensis) from 7 to 21 days of age

The aim of this study was to investigate protein requirements for the maintenance and growth of blue-breasted quail (Excalfactoria chinensis) from 7 to 21 days of age. A total of 180 quails, 7 days old, were randomly assigned to 36 cages and for 2 weeks were fed diets with a metabolisable energy concentration of 12.13 MJ/kg and a dietary CP concentration of 125, 150, 175, 200, 225 or 250 g/kg. The average BW per cage and the feed intake per cage were recorded daily. The results showed that quails fed 125 g/kg CP could not maintain their BW and had negative feed efficiency. There were linear and quadratic relationships between CP level and response criteria, including BW, weight gain, feed intake, feed efficiency, final body nitrogen mass and body nitrogen accretion (P<0.05). The dietary CP requirements, as calculated using a one-slope quadratic broken-line model, were 211 and 202 g/kg according to weight gain and feed efficiency, respectively. The regression equations, on the basis of metabolic BW, of daily weight gain on daily protein intake according to the model were Y=0.137-2.128(0.113-X) if X<0.113 and Y=0.137 if X>or=0.113 (R2=0.96, P<0.001), which meant that the protein requirement for maintenance was 0.049 times the metabolic BW and that to gain 1 g weight quails needed to ingest an extra 0.47 g protein after the maintenance requirement was satisfied. The regression equations, on the basis of metabolic BW, of daily body nitrogen accretion on daily protein intake according to the model were Y=5.667-76.700(0.119-X) if X<0.119 and Y=5.667 if X>or=0.119 (R2=0.95, P<0.001), which meant that quails had to receive an amount of protein equal to their metabolic BW multiplied by 0.045 to satisfy the requirement for maintenance and then ingest an extra 13 g protein to accrete 1 g body nitrogen. In conclusion, growth or protein accretion rates should be regulated according to dietary CP for specific experimental purposes via apportioning protein requirements for maintenance v. growth.     

Net mineral requirements for the growth and maintenance of Somali lambs

Minerals are limiting factors in animal production, and the knowledge of mineral requirements for livestock is crucial to the success of a commercial enterprise. Hair sheep may have different mineral requirements than those presents by the international committees. A study was carried to evaluate the net calcium (Ca), phosphorus (P), magnesium (Mg), sodium (Na), potassium (K), zinc (Zn), iron (Fe), manganese (Mn) and copper (Cu) requirements for the growth and maintenance of Brazilian Somali lambs. A total of 48 hair lambs (13.5±1.8 kg) aged 60±15 days were allocated to individual pens. Eight animals were slaughtered at the beginning of the experiment to serve as a reference group to estimate initial empty BW (EBW) and initial body composition. The remaining lambs (n=40) were assigned to a completely randomized design with eight replications in five levels of metabolizable energy (ME; 4.93, 8.65, 9.41, 10.12 and 11.24 MJ/kg DM). When the lambs of a given treatment reached an average BW of 28 kg, they were slaughtered. Initial body composition was used to calculate the retention of minerals. Mineral body composition was fit using a logarithmic equation in the form of a nonlinear model. The maintenance requirements were estimated from regressions of mineral retention in the empty body on mineral intake. The body mineral concentration decreased in lambs with a BW ranging from 15 to 30 kg. The net mineral requirements (100 g/day of average daily gain (ADG)) decreased from 0.52 to 0.51 g for Ca, 0.28 to 0.23 g for P, 0.02 to 0.02 g for Mg, 0.09 to 0.08 g for Na, 0.11 to 0.09 g for K, 1.30 to 1.08 mg for Zn, 3.77 to 3.22 mg for Fe, 0.08 to 0.06 mg for Mn and 0.09 to 0.08 mg for Cu when BW increased from 15 to 30 kg. The daily net requirements for maintenance per kilogram of BW were 30.13 mg of Ca, 27.58 mg of P, 1.26 mg of Mg, 4.12 mg of Na, 8.11 mg of K, 0.133 mg of Zn, 0.271 mg of Fe, 0.002 mg of Mn and 0.014 mg of Cu. The results of this study indicate that the net mineral requirements for weight gain and maintenance in Brazilian Somali lambs are different than the values that are commonly recommended by the main evaluation systems for feed and nutritional requirements for sheep. These results for the nutritional requirements of minerals may help to optimize mineral supply for hair sheep.     

Energy requirements and efficiency of Alpine goats in early lactation

Dairy goats may rely heavily on body fat and protein reserves in early lactation. Therefore, we aimed to determine the energy requirement and estimate the efficiency of utilization the nutrients of tissues mobilized in the first 8 weeks of lactation for milk production using the comparative slaughter technique. The average initial body mass of 51 multiparous goats was 57.19 ± 8.38 kg and a body condition score of 3.0 ± 0.5. Three goats were slaughtered at the beginning of the experiment to serve as baseline animals to estimate initial empty BW and initial body composition. We used a complete randomized design in which the factor was the day of lactation for slaughtering (the 7th, 14th, 21st, 28th, 35th, 42nd, 49th and 56th day), with six repeats, totalling 48 goats. No fasting before slaughtering. All animals received a single experimental diet. The efficiency of transferring energy from body reserves to milk was estimated using a multiple linear regression equation yielding a value of 0.76. The total energy stored in the empty body decreased over the eight lactation weeks, from 726.47 ± 26.19 to 316.18 ± 49.21 MJ, a 56.47% reduction, mainly because of a reduction in the energy from internal fat of 3.96 ± 1.98 MJ/day. In conclusion, the net energy required for maintenance is 60 ± 30 kJ/BW^0.75 per day, and the net energy required for lactation decreases 70 ± 30 kJ/day during the first eight lactation weeks.     

Fat mass deposition during pregnancy using a four-component model.

Estimates of body fat mass gained during human pregnancy are necessary to assess the composition of gestational weight gained and in studying energy requirements of reproduction. However, commonly used methods of measuring body composition are not valid during pregnancy. We used measurements of total body water (TBW), body density, and bone mineral content (BMC) to apply a four-component model to measure body fat gained in nine pregnant women. Measurements were made longitudinally from before conception; at 8-10, 24-26, and 34-36 wk gestation; and at 4-6 wk postpartum. TBW was measured by deuterium dilution, body density by hydrodensitometry, and BMC by dual-energy X-ray absorptiometry. Body protein was estimated by subtracting TBW and BMC from fat-free mass. By 36 wk of gestation, body weight increased 11.2 +/- 4.4 kg, TBW increased 5.6 +/- 3.3 kg, fat-free mass increased 6.5 +/- 3.4 kg, and fat mass increased 4.1 +/- 3.5 kg. The estimated energy cost of fat mass gained averaged 44,608 kcal (95% confidence interval, -31, 552-120,768 kcal). The large variability in the composition of gestational weight gained among the women was not explained by prepregnancy body composition or by energy intake. This variability makes it impossible to derive a single value for the energy cost of fat deposition to use in estimating the energy requirement of pregnancy.     

Low sanitary conditions increase energy expenditure for maintenance and decrease incremental protein efficiency in growing pigs

Requirements for energy and particular amino acids (AAs) are known to be influenced by the extent of immune system stimulation. Most studies on this topic use models for immune system stimulation mimicking clinical conditions. Extrapolation to conditions of chronic, low-grade immune system stimulation is difficult. We aimed to quantify differences in maintenance energy requirements and efficiency of energy and protein used for growth (incremental energy and protein efficiency) of pigs kept under low (LSC) or high sanitary conditions (HSC) that were fed either a basal diet or a diet with supplemented AA. Twenty-four groups of six 10-week-old female pigs were kept under either LSC or HSC conditions for 2 weeks and fed a diet supplemented or not with 20% extra methionine, threonine and tryptophan. In week 1, feed was available ad libitum. In week 2, feed supply was restricted to 70% of the realized feed intake (kJ/(kg BW)^0.6 per day) in week 1. After week 2, fasting heat production (FHP) was measured. Energy balances and incremental energy and protein efficiencies were measured and analyzed using a GLM. Low sanitary condition increased FHP of pigs by 55 kJ/(kg BW)^0.6 per day, regardless of diet. Low sanitary condition did not alter the response of faecal energy output to incremental gross energy (GE) intake, but it reduced the incremental response of metabolizable energy intake (12% units), heat production (6% units) and energy retained as protein (6% units) to GE intake, leaving energy retained as fat unaltered. Incremental protein efficiency was reduced in LSC pigs by 20% units. Incremental efficiencies for energy and protein were not affected by dietary AA supplementation. Chronic, low-grade immune stimulation by LSC treatment increases FHP in pigs. Under such conditions, the incremental efficiency of nitrogen utilization for body protein deposition is reduced, but the incremental efficiency of absorbed energy for energy or fat deposition is unaffected.     

Energy and protein requirements for maintenance of Texel lambs

It can be hypothesized that the body composition characteristics of different sheep breeds affect their nutritional requirements. However, no study has yet been carried out to determine the nutritional requirements for maintenance of Texel purebred lambs, despite their growing importance in sheep meat production globally. Our objective was therefore to determine the energy and protein requirements for maintenance of Texel lambs. Thirty-four Texel lambs were used, all intact males that were weaned at 50 days old, and confined in individual pens. Two experiments were conducted, as follows. In Experiment 1, a digestibility assay was performed to determine the dietary energy value, in a 3×3 double Latin square design, in which lambs were submitted to three levels of feed restriction (0%, 55% and 70% of ad libitum feed intake). In Experiment 2, the energy and protein requirements for maintenance of Texel lambs from 21 to 40 kg BW were determined using a randomized block design, in which lambs were also submitted to three levels of feed restriction (0%, 55% and 70% of ad libitum feed intake). The requirements for net energy for maintenance (NE_m), metabolizable energy for maintenance (ME_m), net protein for maintenance (NP_m) and metabolizable protein for maintenance (MP_m) were determined. The digestibility of dry matter, energy, protein and metabolizability were similar between food restriction levels, averaging 74.4%, 75.5%, 80.3% and 0.636, respectively. The NE_m determined for growing Texel lambs was 263 kJ/kg of the metabolic fasting BW (FBW), the ME_m was 417 kJ/kg^0.75 FBW and the efficiency of use of ME_m was 0.63. In addition, the NP_m was 1.24 g/day per kg^0.75 FBW and the MP_m was 2.98 g/day per kg^0.75 FBW. The energy requirements of Texel lambs are different from those reported in the literature, possibly due to differences between breeds, diets and environmental effects, whereas the protein requirements are different from literature mainly due to methodological differences; further studies are need to address these aspects that affects the nutritional requirements for raising sheep from different breeds in different environments.     

Amino acid requirement of growing pigs depending on amino acid efficiency and level of protein deposition. 2nd communication: threonine

This study was conducted to evaluate the variability of the efficiency of threonine in different feed proteins for growing pigs. This information is of importance for actual conclusions about threonine requirement within the exponential N-utilization model (Liebert and Gebhardt, 1986) used in our investigations. Wheat (as basal protein), high-protein soybean meal, low-protein soybean meal, rapeseed meal, field bean (Vicia faba), peas (Pisum sativum), corn gluten meal and soybean protein concentrate were used as protein sources. Fifty-six growing barrows (40-65 kg BW) of the genotype Piétrain x (Duroc x Landrace) were randomly allotted to eight N-balance experiments (n = 7). Diets were formulated with two main ingredients (wheat + one feed protein) with threonine as the first limiting amino acid in the mixture which was partly supplemented with crystalline amino acids. Based on N-balance data, the efficiency of threonine was determined in protein mixtures and individual feed proteins. Threonine requirement was calculated depending on efficiency of threonine and level of daily protein deposition. The results from the present studies indicate that the efficiency of threonine in different feed proteins varied in a wide range. Consequently, this factor has to be taken into account for requirement calculations. The threonine requirement depending on daily protein deposition (130, 145 and 160 g) and the efficiency of threonine according to different reference units (g/BW(kg)(-0.67)/d, g/d and % of threonine in the diet) were calculated. The threonine requirement of growing barrows (50 kg BW) corresponding to an average threonine efficiency was 8.52, 9.92 and 11.61 g/d for a daily protein deposition of 130, 145 and 160 g, respectively. The results for a daily protein deposition of 145 or 160 g are in agreement with actual studies and recommendations for threonine supply.     

The effect of lysine intake on energy partitioning and utilization in growing pigs

An experiment utilizing 12 castrated male pigs within a body weight range of 23 - 147 kg was conducted to ascertain whether the alteration of protein quality by varying the level of lysine intake is influencing total energy retention, heat production and therewith efficiency of energy utilization for growth. The animals were allotted to two treatments of a constant medium (11.5 g/d) or high lysine intake (13.5 g/d) level on the basis of an isonitrogenous diet at an energy intake level of 1.3 MJ ME/kg BW0.75. Representing a tool for determining body composition, at target body weights of 35, 55, 80, 115 and 145 kg measurements of deuterium dilution space were undertaken. Protein and lipid accretion were calculated by difference, assuming accretion to contain 23.8 and 39.0 kJ/g, respectively. The results show a significant effect (p < 0.05) between treatment groups for the values of energy retained in protein, thus ensuring the intended alteration by protein quality. Furthermore total energy retention, heat production (difference between ME intake and energy retention) and therewith energy utilization demonstrate independence from the composition of body weight (BW) gain. These observations confirm earlier results, but however, seem to be in contrast to the supposition of a constant efficiency for protein (kp) and fat (kf) accretion, respectively. This may be attributed to a variable kp, in fact to a smaller kp at minor values for protein accretion due to an increased whole body protein turnover. Lacking evidence from experimental data for advantages in using constant values for kp and kf to determine the accurate energy requirement for growth, a uniform value for the efficiency of total energy retention seems to be more adequate.     

Histidine maintenance requirement and efficiency of its utilization in young pigs

Abstract

An experiment was conducted in young pigs (initial BW 10.1 kg) to estimate the maintenance requirement for histidine and its efficiency of utilization for protein accretion using a comparative slaughter technique. Three groups of six pigs each were fed a purified diet supplying 0, 14 or 56 mg histidine per kg BW^0.75. Following 21 d of feeding, pigs were killed for whole body compositional analysis. A representative group of six pigs was killed at the beginning of the experiment. Retention of histidine and total N were the main criteria of response. Histidine retention (R² = 0.73) and N retention (R² = 0.78) were linear functions of histidine intake (p < 0.001). Histidine requirement for zero histidine retention was 15.5 mg/kg BW^0.75, whereas histidine required for zero N retention was 4.1 mg/kg BW^0.75. At zero histidine retention, the pigs retained daily 82 mg N/kg BW^0.75, presumably due to the degradation of histidine-rich compounds such as haemoglobin and/or carnosine. The slope of the regression line relating histidine retention to N retention indicated that 105 mg of histidine was deposited per gram of total N which was considerably less than the estimated histidine concentration in body protein (179 mg/g N). Based on the slopes of regression equations for histidine and N retention, marginal efficiency of histidine utilization was calculated to be 0.94 and 1.34, respectively.     

Deposition of copper, iron, manganese and zinc in the empty body of growing lambs of the breed German Merino Landsheep

A growth experiment with 108 lambs (breed: German Merino Landsheep) was carried out to examine the effect of gender, body weight (BW) and feeding intensity on the deposition of Fe, Zn, Cu and Mn in the empty body (whole animal minus contents of the gastrointestinal tract and bladder). The lambs (50% female and 50% male animals) were fed at three feeding levels ('low', 'medium' and 'high' by varying daily amounts of concentrate and hay) and slaughtered at different final BWs (30, 45 or 55 kg). Six male and six female animals were killed at a BW of 18 kg representing the animals' BW at the beginning of the comparative slaughter experiment. There were significant main effects for the treatments growth rate and final weight on the daily rate of accretion of the trace elements examined. Feeding intensity had a marked influence on the accretion rate for Fe (P < 0.001), Zn (P < 0.001), Cu (P < 0.001) and Mn (P = 0.003). With increasing feeding intensity (low, medium, high) the daily deposition of these trace elements increased (4.4, 5.2, 6.6 mg/day for Fe; 4.9, 5.5, 6.9 mg/day for Zn; 0.20, 0.36, 0.44 mg/day for Cu; 0.14, 0.16, 0.21 mg/day for Mn). Heavier final BW led to increased daily retention of Zn (P < 0.001) and Mn (P = 0.002). Gender had a marked influence only on the accretion rate for Zn (P < 0.001). Ram lambs had a higher daily deposition of this element than female lambs. Related to 1000 g empty body gain, the following concentrations were found for the trace elements examined: Fe 26.1 mg, Zn 30.0 mg, Cu 1.41 mg and Mn 1.04 mg. A feeding influence was given for Zn (P < 0.001) and Cu (P = 0.039). Feeding level low had higher Zn and lower Cu concentrations. Male animals showed less Fe (P < 0.001) and Zn (P = 0.034) per kg empty body gain than females.     

Untersuchungen über die Qualität des Futtereiweißes bei Legehennen

Aim of the studies was to attain new scientific findings for the influence of the physiological state of sows (non‐pregnant and pregnant respectively) on energy and nitrogen metabolism. The experiments were carried out according to a 3 x 3 factorial experimental plan with 3 variants of litter number (1, 2 and 4) and 3 variants of energy supply (120, 100 and 80%). Within the variants the non‐pregnant and pregnant sows were fed equally related to the metabolic live weight. The metabolism measurements run from the 1^st to the 115^th experimental and gestation day respectively. The methods of indirect calorimetry and slaughtering technique were applied. The chemical composition of the whole bodies of the non‐pregnant sows was like that of the maternal bodies of the pregnant sows (dry matter 410 g/kg, protein 160 g/kg and fat 210 g/kg). The physiological state for the sows did not influence the nutrients digestibility (OM 77.0 and 76.7%) and the energy metabolizability. About conformable intakes of metabolizable energy (601 and 586 kJ/kg LW ^0,75·d) and of digestible nitrogen (0.77 and 0.75 g/kg LW ^0,75·d) in non‐pregnant and pregnant sows resulted in higher deposition of energy (64 and 79 kJ/kg LW ^0,75·d) and of nitrogen (0.15 and 0.19 g/kg LW ^0,75·d) in the pregnant sows due to energy and nitrogen deposition in the conception products and in the reproductive organs. The energy maintenance requirement and the partial efficiency of the energy utilization for the deposition as well as the nitrogen maintenance requirement and the partial efficiency of the nitrogen utilization for the deposition in the non‐pregnant and the pregnant sows were determined.     

Amino acid requirement of growing pigs depending on amino acid efficiency and level of protein deposition 1st communication: lysine

The study was conducted to evaluate the variability of efficiency of lysine utilisation in different feed proteins for growing pigs including wheat, unprocessed soybean flakes (SF), hydrothermal processed SF, corn gluten meal (CGM), two batches of soybean protein concentrate (SPC-1, SPC-2), different batches of peas (Pisum sativum) and field beans (Vicia faba). Data about efficiency of lysine are important for further conclusions related to lysine requirement in dependence on level of daily protein deposition. In N-balance studies 161 growing barrows (40-65 kg BW) of the genotype [Piétrain x (Duroc x Landrace)] were randomly allotted into 23 experimental treatments (n = 7) with diets in which lysine was the first limiting amino acid. Data from the N-balance trials were used to calculate efficiency of lysine and consequently lysine requirement based on an exponential N-utilisation model. Results from the present studies indicate that efficiency of lysine in different feed proteins varies in a very wide range and this variation greatly affected the calculated lysine requirement. Therefore, the variation in efficiency of lysine should be taken into account in requirement calculations and consequently in diet formulation for pigs. The results of model calculation for the lysine requirement depending on daily protein deposition (130, 145 and 160 g/d) and efficiency of lysine are given for different standards for comparison (g x kg(-0.67) x d(-1), g x d(-1) and percentage of lysine in the diet). The calculated lysine requirement of growing barrows (50 kg BW) corresponding to an average lysine efficiency was 15.5, 18.0 and 21.1 g/d for daily protein deposition of 130, 145 and 160 g, respectively. The results of the model calculation for 145 or 160 g daily protein deposition are in agreement with actual studies and recommendations of NRC (1998) and DLG (2002) for lysine supply.     

Lysine maintenance requirement and efficiency of its utilisation in young pigs as estimated by comparative slaughter technique

An experiment was carried out on weaner pigs (initial BW 10.8 kg) to estimate the maintenance requirement for lysine (Lys) and its marginal efficiency of utilisation using a comparative slaughter technique. Three groups of six pigs each were fed purified diets for 21 days supplying Lys at 19.5, 78 or 195 mg/kg W0.75, which corresponded to 50, 200 or 500% of the assumed maintenance requirement. All other essential amino acids were given at 50% excess. At the end of the experiment, pigs were killed for whole-body nitrogen (N) and amino acid analysis. A representative group of six pigs was analysed at the beginning of the experiment. Based on regression equations, relating Lys or N retention to Lys intake, Lys requirement for zero Lys retention was estimated to be 121 mg/kg W0.75, while Lys requirement corresponding to zero N retention was 41.7 mg/kg W0.75. At N equilibrium, the pigs lost 65 mg of Lys per kg W0.75 daily while at zero Lys retention, the daily N retention was 156 mg/kg W0.75 . The marginal efficiency of lysine utilisation was 0.91. It is concluded that zero lysine retention is a better criterion of lysine maintenance requirement than zero N retention.