Effect of feed intake on endogenous losses and amino acid and energy digestibility by growing pigs

An experiment was conducted to determine the effect of feed intake (FI) on endogenous losses and the digestibility of CP and AA by growing pigs. Six growing barrows (initial BW = 70.3 kg) had a T-cannula installed in the distal ileum and were used in a 6 x 6 Latin square design. A soybean meal cornstarch-based diet and a N-free diet were formulated. Chromic oxide (0.25%; as-fed basis) was included in both diets as an inert marker. Each diet was provided at three different levels of FI. Feed intake level 1 was equal to the estimated energy requirement for maintenance of the pigs, whereas levels 2 and 3 were two or three times this amount, respectively. Each experimental period lasted 7 d. The initial 4 d of each period comprised an adaptation period to the experimental diets. On d 5, fecal samples were collected, while ileal digesta were collected during two 10-h periods on d 6 and 7. Between each experimental period, a corn-soybean meal-based diet (16% CP) was fed to all pigs for 7 d. The basal ileal endogenous losses (IAA(end)) of CP and AA were measured for each level of FI from pigs fed the N-free diet. Likewise, the apparent (AID) and standardized (SID) ileal digestibility coefficients for CP and AA in soybean meal were calculated for each level of FI. The total-tract digestibility coefficient of energy in the soybean meal-based diet also was calculated. The AID for CP and all indispensable AA except Lys, Met, and Thr increased (P < or =0.055) as FI increased. The IAA(end) of CP and all AA except Pro decreased linearly (P < 0.05) as FI increased when expressed as g/kg of DMI; however, the total daily IAA(end) increased as FI increased (linear, P < or =0.056) for all AA, except for Phe, Thr, Trp, Val, Cys, Gly, and Ser. The AA composition (% of CP) of endogenous protein was not affected by the level of FI, except for Arg, Thr, Pro, and Ser. As FI increased, the SID decreased linearly (P < 0.04) for CP and all AA, except Arg, Trp, Asp, Pro, and Tyr. The total-tract digestibility of energy was not influenced by the FI level. These results demonstrate that the FI level significantly influenced AID, SID, and IAA(end) for CP and AA. Therefore, pigs used to measure AA digestibility coefficients and IAA(end) should be fed at a level that is close to what is used under commercial conditions.     

Measurement of endogenous amino acid losses in poultry

1. Ileal endogenous amino acid losses were determined in broiler chickens and in cannulated cross‐bred layer strain cockerels using either a nitrogen‐free diet, regression analysis or a 48 h fast.

2. Endogenous amino acid flows to the ileum in fasted cockerels were significantly lower than those obtained both by feeding the nitrogen‐free diet, and from regression analysis in either broilers or cockerels. Regression analysis gave the highest flows.

3. The apparent digestibility coefficients of amino acids in a diet containing 200 g/kg crude protein were lower in broilers (0.84) than in cockerels (0.88). When corrected, by regression analysis, for the contribution of endogenous amino acids, the true digestibility coefficients became 0.90 and 0.92 respectively.     

A calorimetric estimate of the efficiency of utilisation of dietary energy by the growing cockerel

The metabolic rates of four growing cockerels, aged between 10 and 18 weeks, were measured using respiration calorimetry. Measurements were made when the birds had been fasted for 48–72 h and when they had been given a cereal‐type diet at maintenance and production levels.

The mean fasting heat production (±SE) was 92.3 (±5.0) kcal/kg d or 113.4 (±5.7) kcal/kg3/4 d. The relationship between energy balance (T) and ME intake (X) was calculated to be Y = 0.851X—92.9 indicating that the maintenance ME requirement was 109.1 kcal/kg d and that the net availability of the ME was 85.1 per cent. The efficiency of energy utilisation in relation to plane of nutrition and to the amount of protein and fat deposited is discussed.     

Estimating energy losses with urine in the cat

Urinary energy losses in cats have to be determined in energy balance trials as well as for the calculation of the metabolizable energy (ME) content of cat food. The aim of the present study was: first, to assess whether the energy content of cat urine quantified by bomb calorimetry differs from that quantified using GE (kJ) urine = 33 kJ × g C urine + 9 kJ × g N urine and investigate whether this difference could be attributed to influences of diets. Second, to assess whether the subtraction of 3.1 kJ/g of protein intake used for estimation of metabolizable energy content of cat foods is confirmed as usable. Data from 27 energy and protein balance trials from different studies with complete sampling of urine and faeces (29 cats in part A and 35 cats in part B) were used. Gross energy, carbon and nitrogen were determined in food, faeces and urine. Gross energy values in urine tended to be higher when determined with the formula of Hoffman and Klein compared to bomb calorimetry. The average relative difference of gross energy values between the methods was 18.8%. The mean energy loss in kJ/g of protein intake resulted in 3.7 kJ/g protein intake, which was not statistically significantly different (p = 0.12) from the tested value of 3.1 kJ/g of protein intake. In conclusion, the formula of Hoffman and Klein is not appropriate for the estimation of energy in cat urine. In balance studies, it is advisable to quantify the urinary energy content by bomb calorimetry. In the second part of the study, the protein correction factor to determine ME of 3.1 kJ/g protein intake for urinary energy losses of Kienzle et al. could be confirmed.     

Estimation of endogenous protein and amino acid ileal losses in weaned piglets by regression analysis using diets with graded levels of casein

Background： Many studies have investigated endogenous loss of proteins and amino acids （AAs） at the ileal level in growing pigs. However, only a few studies have researched this subject in piglets. Knowledge regarding AA ileal digestibility in piglets would be helpful during the formulation of diets for weaning piglets, rather than just using coefficients obtained in growing pigs. Therefore, in this study, we sought to estimate endogenous protein and AA ileal losses in piglets. Furthermore, apparent and true ileal digestibility （AID and TID） of protein and AAs from casein were measured. Results： The average flow of protein was 20.8 g/kg of dry matter intake （DMI）. Basal protein loss, as estimated by regression, was 16.9 g/kg DMI. Glutamic acid, arginine, and aspartic acid （2.2, 1.4, and 1.2 g/kg DMI, respectively） were the AAs for which greater losses were seen. The AID of protein and AAs increased as the protein level in the diet increased. A higher increment in AID was observed between diets with 80 and160 g CP/kg of feed; this finding was mainly attributable to increases in glycine and arginine （46.1% and 18%, respectively）. The TID of protein was 97.8, and the TID of AAs varied from 93.9 for histidine to 100.2 for phenylalanine. Conclusions： The basal endogenous protein loss in piglets was 16.9 g/kg DMI. Endogenous protein was rich in glutamic acid, aspartic acid, and arginine, which represented 32.7% of endogenous protein loss in weaning piglets. The TID of casein was high and varied from 93.0 for histidine to 100.2 for phenylalanine.     

Estimation of endogenous protein and amino acid ileal losses in weaned piglets by regression analysis using diets with graded levels of casein

Background

Many studies have investigated endogenous loss of proteins and amino acids (AAs) at the ileal level in growing pigs. However, only a few studies have researched this subject in piglets. Knowledge regarding AA ileal digestibility in piglets would be helpful during the formulation of diets for weaning piglets, rather than just using coefficients obtained in growing pigs. Therefore, in this study, we sought to estimate endogenous protein and AA ileal losses in piglets. Furthermore, apparent and true ileal digestibility (AID and TID) of protein and AAs from casein were measured.

Results

The average flow of protein was 20.8 g/kg of dry matter intake (DMI). Basal protein loss, as estimated by regression, was 16.9 g/kg DMI. Glutamic acid, arginine, and aspartic acid (2.2, 1.4, and 1.2 g/kg DMI, respectively) were the AAs for which greater losses were seen. The AID of protein and AAs increased as the protein level in the diet increased. A higher increment in AID was observed between diets with 80 and160 g CP/kg of feed; this finding was mainly attributable to increases in glycine and arginine (46.1% and 18%, respectively). The TID of protein was 97.8, and the TID of AAs varied from 93.9 for histidine to 100.2 for phenylalanine.

Conclusions

The basal endogenous protein loss in piglets was 16.9 g/kg DMI. Endogenous protein was rich in glutamic acid, aspartic acid, and arginine, which represented 32.7% of endogenous protein loss in weaning piglets. The TID of casein was high and varied from 93.0 for histidine to 100.2 for phenylalanine.     

The effect of supplementary bacterial phytase on dietary metabolisable energy, nutrient retention and endogenous losses in precision fed broiler chickens

Thirty-two Ross 308 male broiler chickens were used in a precision feeding assay to investigate the effect of exogenous phytase (EC 3.1.3.26) on dietary apparent metabolisable energy (AME), dry matter digestibility (DMD) coefficient, nitrogen (NR), amino acid and mineral retentions. The excretion of endogenous losses measured as sialic acid (SA) was also determined. Four dietary treatments (control (C), C + 250 FTU (phytase units per kg feed), C + 500 FTU, and C + 2500 FTU) were studied with each treatment replicated eight times in randomised complete block design. Diets were formulated to be nutritionally adequate with the exception of available P content (2.3 g/kg non-phytate P). Over the 48-h collection period, the phytase fed birds retained 29.3 mg more Na and 2.3 mg more Zn (p < 0.05) than the control fed birds, with the relationship between phytase dose and Na and Zn retention being best described by a linear function (p < 0.05 and p < 0.001, for Na and Zn, respectively). Phytase supplementation did not have an effect on dietary AME, DMD and NR. However, increasing the dose of phytase led to a linear increase in dietary amino acid retention (p < 0.05). Dietary phytase decreased total sialic acid excretion in a linear fashion (p < 0.05). It can be concluded that supplementary phytase increases the retention (reduces the excretion) of dietary Zn and Na in broiler chickens. The beneficial effects of the addition of exogenous phytases to poultry diets seems to be mediated through improved dietary nutrients absorption and reduced endogenous losses.     

The effects of supplementary bacterial phytase on dietary true metabolisable energy, nutrient digestibility and endogenous losses in precision fed turkeys

1. A total of 40 female BUT9 turkeys were used in a precision-feeding assay to investigate the effect of dietary phytase on true metabolisable energy corrected for N retention (TME(N)), coefficients of true dry matter (TDMD), mineral, amino acid and nitrogen (TND) digestibilities and the excretion of endogenous mucin, measured as sialic acid (SA). 2. Five treatments were used in this study: control (C), C + 250 phytase units (FTU) per kg feed, C + 500 FTU, C + 2500 FTU, and glucose only for endogenous losses estimation. Diets were formulated to be nutritionally adequate with the exception that the P content was relatively low (3·6 g/kg non-phytate P). 3. Inclusion of phytase increased TND in a quadratic manner with the optimum being achieved at approximately 500 FTU, at which TND was 37 % greater than in the control. The concentration of SA in the excreta decreased linearly with increased phytase supplementation. Dietary TME(N), TDMD and true mineral digestibility coefficients were not significantly affected by phytase supplementation. 4. Phytase inclusion increased digestibility coefficients for indispensable, dispensable and total amino acids in a linear manner. The scale of the response to phytase was greatest with threonine and least with lysine digestibility, suggesting a specific mechanism of action that benefits gut health. 5. The strong negative relationship between secretion of SA and threonine digestibility suggests that a large part of the threonine benefit may be from reduced mucin synthesis. This supports the hypothesis that dietary phytase may play a role in improving the health status of the intestine and, as a result, reduces the maintenance energy requirements of turkeys.     

Determination of endogenous nitrogen in feces using the isotope technic

A ration consisting of wheat gluten and N-free components was supplemented with L-lysine and L-leucine and fed to two groups of growing Wistar rats. Group 1 received 15N Lys and unlabelled Leu, group 2 received unlabelled Lys and 15N Leu in order to study the influence of the utilization of the 15N marker on the labelling quota of faeces and urine as well as various fractions of the body. The good utilization of Lys in group 1 results in a higher 15N excess in faeces and a reduced 15N abundance in urine in comparison to group 2 with a lower utilization of 15N Leu. The results show that the 15N abundance in urine is unsuitable as an indicator of the 15N labelling quota of endogenous metabolic faecal nitrogen.     

Carbon and nitrogen losses through moulting in the Cape rock lobster Jasus lalandii

Moulting data were collected from a size range of J. lalandii in an aquarium where field conditions of light intensity and temperature were simulated. Elemental analysis was carried out on intermoult exoskeleton, exuviae and whole lobsters. Lobsters lose a mean of 27% of their dry mass per year at ecdysis. Exuviae contained a higher ash content, a 28,1 % lower organic carbon content indicating reabsorption, and a similar inorganic carbon content when compared with intermoult exoskeleton. Estimates for a lobster population occupying 100 m² at Robben Island are that 228 g organic carbon and 57,3 g nitrogen are lost annually. However, the annual cost of moulting to J. lalandii in terms of exuvial mass, which includes carbon and nitrogen, is considerable when viewed in terms of lost production.     

The effect of previous exposure to dietary microbial phytase on the endogenous excretions of energy, nitrogen and minerals from turkeys

1. A precision feeding experiment was conducted with turkeys, which had previously been fed diets with or without phytase, to study the effects on the excretions of endogenous energy (EEL), nitrogen (ENL), amino acids (EAAL) and minerals. 2. Female turkeys (BUT 6) which had been fed one of 4 experimental diets (low P maize-soya diets (control, C), C + 250 international units of phytase/kg diet (FTU), C + 500 FTU and C + 2500 FTU) were used in this study. All birds were fasted and then given 50 mL of glucose solution at 46 d of age. Birds were allocated to individual metabolism cages in a randomised block design with 8 replicates for each of the 4 previously-fed diets. 3. The response of EEL and ENL to phytase pre-exposure was linear. An increase of 100 FTU reduced the EEL and ENL by approximately 1·6 kJ and 20 mg respectively. The results suggest that a minimum activity of phytase of 500 FTU is needed to initiate the reduction of these losses. 4. Pre-exposure to phytase reduced the EAAL, which was best described as a linear response with increasing phytase dose in the pre-study period. An increase of 100 FTU reduced the losses of total endogenous amino acids by approximately 225 mg. 5. In contrast to the results for endogenous energy losses, turkeys pre-exposed to phytase linearly increased their excretions of Ca and Mg with increasing phytase activity in the pre-study period. 6. The effects of feeding turkeys with supplementary phytase continued for at least 4 d after the diets were withdrawn. This suggests that exposure to phytase alters the functionality and secretions of the gastrointestinal tract, which may influence the nutritive value of diets fed immediately after.     

妊娠前期黔北麻羊能量和蛋白需要的估算

为明确妊娠前期黔北麻羊能量和蛋白的营养需要量,本研究挑选36只体重相近[(27.45?±?0.29)?kg]、妊娠期邻近[(30?±?3)?d]、健康的二胎黔北麻羊母羊,完全随机分成4组,每组3个重复,每个重复3只羊.以妊娠前期母羊营养需要的60％、80％、100％和120％进行饲喂,预试期10?d,正试期30?d,在正试期的最后7?d用全收粪法收集粪尿.建立能量和蛋白摄入量与体重及日增重的回归方程,得到妊娠前期黔北麻羊母羊维持与生长的能量和蛋白需要量.结果表明:随着营养水平的增加,黔北麻羊总能摄入量、消化能摄入量、代谢能摄入量、粗蛋白摄入量、可消化蛋白摄入量和可代谢蛋白摄入量增加,黔北麻羊平均日增重也随之增加.妊娠期前期黔北麻羊母羊维持代谢能需要量为447.10?kJ·kg?1?BW0.75,增重所需代谢能为29.80?kJ·g?1;维持所需可消化蛋白量为2.75?g·kg?1?BW0.75,增重所需可消化蛋白量为0.22?g·g?1.综上,提高营养水平可增加山羊养分摄入量和增重,山羊的能量和蛋白的维持和增长需要均与美国国家科学研究委员会(United?States?National?Research?Council,?NRC)山羊营养需要相近.     

内源异黄酮对紫花苜蓿结瘤固氮及氮效率的调控研究北大核心CSCD

为探究紫花苜蓿体内异黄酮与结瘤固氮及氮效率的关系,以紫花苜蓿品种中氮高效的"LW6010"和氮低效的陇东苜蓿为材料,采用室内营养液砂培,设5个氮素水平,研究了不同氮效率紫花苜蓿的异黄酮含量和固氮特性以及异黄酮合酶(IFS)和结瘤信号传递通路基因(nod)的表达。结果表明:紫花苜蓿的异黄酮含量与根瘤数、单株总根瘤重以及单株固氮潜力的相关性显著,并且在低氮胁迫时紫花苜蓿的异黄酮含量以及根瘤数、单株总根瘤重和单株固氮潜力均显著上升。另外,还发现:氮高效的"LW6010"紫花苜蓿在氮胁迫时,茎叶和根系中上调的IFS基因数量和上调幅度均大于氮低效的陇东苜蓿,因此促进了nod基因的高表达,最终提高了氮效率。综上所述,1)紫花苜蓿的结瘤固氮与异黄酮含量显著正相关,在外源氮素浓度改变时,紫花苜蓿能通过茎叶和根系中不同IFS基因的表达提高体内异黄酮含量,从而刺激nod基因表达来促进结瘤和提高单株固氮潜力;2)紫花苜蓿体内异黄酮含量的差异是决定其氮效率高低的重要原因,氮高效紫花苜蓿在氮胁迫时通过多个IFS基因的高表达促进异黄酮合成,进而刺激结瘤固氮,从而表现出氮高效。     

Urinary energy losses in dogs fed commercial extruded foods

Energy and nitrogen losses in the urine were recorded in 134 individual balances with adult (1- to 2-year-old) female Beagles that were fed 23 dry extruded dog foods ranging in crude protein (CP) content from 242 to 360 g/kg dry matter. The energy equivalent of urinary nitrogen was estimated as 33.9 kJ/g N. Both energy losses in the urine corrected for the nitrogen balance, and the metabolizable energy (MEn): digestible energy (DE) ratio were found to be closely related to diet CP content (r : 0.851 and 0.820). The MEn content of extruded dog foods can be accurately calculated from the DE content, either by subtracting 4.59 MJ/kg CP or estimating the MEn/DE ratio from the food CP content by the following equation: MEn/DE=0.98 – 3.44 ± 0.517 × CP (kg/MJ DE).     

Ultrastructure of fibroblasts from the comb of the cockerel

1. Fibroblasts in the intermediate layer of comb dermis of intact single‐combed White Leghorn cocks and testosterone‐injected capons, all 82 days of age, were divided into three types, namely A, B and C, according to the ultrastructure of these cells. All the fibroblasts in the same tissue from capons were type C.

2. The Golgi complex and the rough endoplasmic reticulum were well developed in type A and type B fibroblasts. The latter organelle in type A fibroblasts was in the form of long parallel cisternae spaced a uniform distance apart, while that in type B fibroblasts was extremely distended, branched and anastomosed, containing flocculent material in the cisternae. In type C fibroblasts, both the Golgi complex and the rough endoplasmic reticulum were poor.     

同位素标记内源氮法测定回肠内源氨基酸排泄量研究进展

内源氨基酸排泄量(LEAA)是测定饲料氨基酸真消化率的重要指标,而同位素标记内源氮法是直接测定内源氨基酸排泄量的有效方法之一。本文综述了同位素标记内源氮法测定回肠内源氨基酸排泄量的基本原理、假设条件和影响因素。     

玉米秸青贮损失及其评估

通过对不同品种不同收获期玉米秸青贮期间重量变化测定 ,得出青贮重量损失率。结果表明 :品种不同 ,7个收获期玉米秸青贮损失率平均值变化是 1 6 5 %～ 2 2 6 % (P >0 0 5 ) ;收获时期不同 ,8个品种玉米秸青贮损失率平均值变化是 1 2 2 %～ 3 75 % (P <0 0 5 )。说明 :收获时间 ,特别是收获后期 ,对玉米秸青贮损失影响很大 ,线性评估说明以生长期来评估青贮损失是可取的。     

Comparative apparent metabolisable energy values of high, medium and low tannin varieties of sorghum in cockerel, guinea fowl and quail

1. Nitrogen-corrected apparent metabolisable energy values (AMEN) of three varieties of sorghum (white-low tannin, brown-medium tannin and red-high tannin) were measured in three species of poultry (cockerel, guinea fowl and Japanese quail) by a practical diet replacement (total collection) method. 2. Each variety of sorghum was tested at two concentrations (200 and 400 g/kg of reference diet) in 6 replications with one cockerel or guinea fowl or two quails per replication. The duration of the trial included a 10 d preliminary feeding period (on conventional grower diet) followed by a 12 d adaptation period (on reference and test diets) and a 3 d balance period (with recording of feed intake and excreta output). 3. The calculated AMEN values of different sorghum varieties were: white--12.9, 12.8 and 12.7; brown--12.7, 12.3 and 12.6; and red--11.4, 11.1 and 11.6 MJ/kg for cockerels, guinea fowls and quails, respectively. The mean AMEN value of red sorghum (11.3 MJ/kg) was significantly lower than those of brown (12.5 MJ/kg) or white sorghum (12.8 MJ/kg). A negative correlation was observed between tannin concentration and AMEN. 4. There was no significant difference in the AMEN values of white, brown and red sorghum varieties to the different poultry species. AMEN values of sorghum for the cockerel could, therefore, be used in practical feed formulation for guinea fowl and quail.     

Sexual development and levels of plasma testosterone in the light type of cockerel

The concentration of testosterone in blood plasma during the ontogenetic development of cockerels was studied in relation to the development of spermatogenic part of gonads. On the basis of the results, sexual development of cockerels can be divided into three stages. The first stage (from hatching to the age of eight to nine weeks) was characterized by a slow increase in gonad weight, by low concentration of plasma testosterone (0.4-2.0 nmol/l) and by the occurrence of spermatogonia in testes. In the course of the second stage (from the age of nine to 16 weeks) a rapid increase in the weight of testes and testosterone concentration was observed. At the end of this stage all phases of spermatogenic cycle were observed in gonads; the testosterone levels averaged to 10 nmol/l. In the course of this stage all cockerels reached sexual maturity; large individual differences in spermatogenesis development were observed. The third stage (16 weeks of age and more) was characterized by an intensive spermatogenesis, further increase in gonad weight and by typical variations of the plasma testosterone levels. The concentration of the circulating testosterone increased before the onset of the final stages of the spermatogenic cycle.