The quantification of faecal nitrogen (FN) and of urinary urea-N (UUN) and urinary non-urea-N (UNUN) excretion at varying N contents in ruminant rations is an important tool in assessing endogenous N turnover via the rumino-hepatic cycle. Using a statistical analysis based on an extensive database, the aim of this metaanalysis was to evaluate correlations derived previously by deduction. The data were categorised into dairy cattle, growing cattle (bulls and heifers), sheep and goats. Data from 50 publications were considered. The independent variable was the daily N intake (NI, g/day). The dependent variables were the daily quantities (g/ day) of FN, urinary N (UN) , UUN, UNUN and N retention. The NI influenced FN to differing extents in goats, dairy cattle, growing cattle and sheep (listed in descending order of influence). Except in sheep, the effect was statistically significant. The influence on UN varied in the order goats, growing cattle, dairy cattle and sheep; the effect was statistically significant only for dairy cattle and growing cattle (P < 0.001). The UUN was influenced in the order sheep, goats, dairy cattle and growing cattle (P < 0.05). The UNUN could be assessed only in dairy cattle, growing cattle and sheep and was not influenced by NI. The UUN is therefore more strongly dependent on NI than is UNUN and the latter can therefore continue to be seen as obligatory. The FN is indeed influenced by NI but, as a result of higher digestibility of the total ration with increasing crude protein content, an improvement in microbial crude protein synthesis can also be assumed, which is reflected in higher FN levels.

Insulin-like growth factor-1 (IGF-1), somatolactin and leptin are involved in growth regulation and energy metabolism in fish. We herein focused on serum IGF-1 concentration analysed by enzyme-linked immunosorbent assay in restrictively fed rainbow trout (Oncorhynchus mykiss). The animals were fed a high-fat/low-protein diet at daily feed increases (DFI) ranging from 0.5% to 2% of initial body weight (IBW), starting either at 62 or 176 g IBW. In selected groups, growth hormone receptor 1 (GHR1) and leptin mRNA were quantified in liver, and GHR1 mRNA also in visceral adipose tissue. Serum IGF-1 concentrations in both IBW groups were highest at 2% and 1% DFI and were nonlinearly decreasing with reduced DFI. The low-IBW groups had mostly lower IGF-1 concentrations than the high-IBW groups. Leptin and GHR1 mRNA decreased with feeding intensity in liver, but GHR1 mRNA increased in adipose tissue. IGF-1 is related to growth and may help to mitigate oxidative stress in consequence of lipid mobilization during restrictive feeding. IGF-1 secretion associated with stress response in addition to its function in growth and energy metabolism seemed to reach a point of inflection at DFI 1%. Leptin and GHR1 might be linked to lipid metabolism and free fatty acid partitioning towards liver.

32 Simmental heifers of about 250 kg body weight were fed mixed rations containing, on dry matter basis: 60% maize silage, 10% straw and 30% concentrates. The experiment followed a two-factorial design (2 feeding levels x 4 dietary crude protein concentrations) with 4 repetitions per treatment. Animals were given daily either 68 or 81 g dry matter per kg BW(0.75). Because the concentrates contained one of four different levels of crude protein, dietary crude protein concentrations were 76, 94, 112 or 130 g per kg dry matter, respectively.Following a period from adaptation of 3 weeks, faeces and urine were collected quantitatively for five days. Total N was analyzed in feeds, faeces and urine. Urea was determined in urine as well and the difference between total N and urea-N is defined as non-urea-N.No significant dietary influences were found on faecal N or non-urea-N. A highly significant influence existed, however, of N intake on renal excretion of urea. When N intake exceeded the sum of faecal N plus urinary non-urea-N by up to 20 g daily, then 2.3 +/- 0.13 g N were excreted as urinary urea. With further increase of N intake, 53% of the additional N ingested were excreted as urinary urea and 47% were retained in the body.Calculated efficiencies of utilization of total dietary N for N accretion in the body at growth rates between 400 and 800 g per day were between 17 and 24%, respectively.

From 3 experiments with broiler chicks concerning the effect of a varying supply with nonessential amino acids on the accretion of protein and fat, whole bodies (including feathers) of 135 chicks were analysed (ICP) for the concentration of Ca, P, Mg, Na, K, S, Fe, Cu, Zn und Mn. The mean live weight of 16 three weeks old birds was 630 g, that of 36 five weeks old birds 1740 g, and that of 83 six weeks old birds 1930 g. During the first 3 weeks of life they were a fed commercial starter feed. The diets fed from the 15th day onward consisted of maize, soybean meal, maize-starch, cellulose, soybean oil, a mineral-vitamin-premix and crystalline amino acids. The analysed concentrations of minerals and trace elements were in all diets higher than the recommendations of GFE (1999). Statistical calculations of the data show that the concentrations of the elements in whole body fresh matter as well as in fat free matter differed only slightly in a few cases between the 21 groups of analysed chicks. Analysis of regression showed no influence of the body weight of the birds on the concentration of the elements. Therefore the overall means were calculated from all the analysed chicks. The following means and standard deviations were calculated: in g/kg whole body fresh matter: Ca 6.9 +/- 1.43, P 5.1 +/- 0.74, Mg 0.33 +/- 0.032, Na 1.3 +/- 0.11, K 2.8 +/- 0.14, S 2.7 +/- 0.18, in mg/kg whole body fresh matter: Fe 44 +/- 8.5, Cu 2.0 +/- 0.75, Zn 30 +/- 3.2, Mn 1.2 +/- 0.39.

Bambara groundnut (Vigna subterranea) was analysed for its nutrients content, and subsequently included into standard wheat-soyabean meal diets at the expense of wheat and soyabean meal. All diets had similar crude protein and total lipids contents and met the amino acids, minerals and vitamins requirements according to NRC (1994). In the 1st experiment broiler chickens, kept in individual metabolic cages, were allotted to either a control, or one of 4 test groups, ten birds per treatment. The experiment lasted from 12th to 27th day of life. Growth performance, nutrient balance and energy metabolizability were determined. In a 2nd experiment 35-weeks old Lohmann laying hens were allotted into 4 deep litter pens of 5 layers each. Birds received either a control diet or a test diet containing 451 g Bambara /kg feed. During 10 weeks, egg production and quality were determined. Bambara groundnut inclusion in growing broiler diets had no effect on the feed intake; it contains 12.6 MJ AME /kg DM. There was a progressive decrease in weight gain of the chickens, signifi cant at and above 571 g/kg inclusion. Inclusion of 451g Bambara/kg layers feed had no signifi cant effect on egg production and the quality of eggs fell within an acceptable range.

Lowering the crude protein (CP) concentration in broiler feed while maintaining the essential amino acid (EAA) concentration at the requirement level by supplementing diets with free amino acids is an effective strategy for decreasing the emission of nitrogen. It causes, however, an undesired increase in the deposition of lipids in the broiler. As possible causes the following were investigated: a deficiency of nonessential amino acids (NEAA), a special effect of intact protein, substitution of NEAA by a non-protein energy source. In the first experiment broiler chicks at the age from 3 to 6 weeks kept in single cages besides maize and soybean-meal were fed soy-protein-isolate in diet 1 (223 g CP/kg). In diet 2 (177 g CP/kg) the soy-protein-isolate was substituted mainly by starch and its EAA by free EAA. Diet 3 corresponded to diet 2 except that the CP concentration was increased to that of diet I by supplementation with NEAA at the expense of starch. Compared to diet I the reduction of the CP concentration in diet 2 increased the deposition of lipids by about 30%, whereas weight gain and deposition of protein was unchanged. Increasing the CP concentration by supplementation of NEAA (diet 3) reduced the deposition of lipids to that of diet 1. A specific effect of intact protein was not confirmed.In experiment 2 it was tested, whether the effect of decreasing deposition of lipids can also be obtained by a slight reduction of energy intake. A basal diet was fed ad libitum either with addition of 100 g NEAA (treatment 1) or with addition of 100 g corn starch (treatment 2). In treatment 3 the basal diet was fed without any addition in an amount of 90% of the daily feed intake from treatment 2. The diets contained 251, 180 and 204 g CP/kg, respectively. The reduction of the dietary CP concentration in treatment 2 increased lipid deposition again significantly, whereas weight gain and protein deposition were almost unchanged. The slight reduction of energy intake caused a remarkable reduction of lipid deposition with only a slight decrease in weight gain.The following conclusions can be drawn: Lowering the CP concentration in broiler feed while maintaining the EAA concentration causes an increased deposition of lipids in the broiler, whereas live weight gain and deposition of protein is almost unchanged. An increase of the CP concentration solely by supplementation of NEAA prevents the enhanced deposition of lipids. A direct effect of the CP concentration of the feed on the deposition of lipids in the broiler can be assumed. The increased deposition of lipids due to the reduction of the dietary protein concentration can also be prevented with a slight reduction of energy intake by restricted feeding. A specific effect of an intact protein was not confirmed.

It was the aim of this study to examine the potential regulatory effects of a long-term low dietary protein supply on the transport capacity of the jejunal brush-border membrane for amino acids. For this purpose, we used the neutral amino acids l-alanine (representative for nonessential amino acids) and l-leucine (representative for essential amino acids) as model substances. Ten sheep lambs, 8 weeks of age and 19–27 kg body weight, were allotted to two dietary regimes with either adequate or reduced protein supply which was achieved by 17.9% and 9.7% of crude protein in the concentrated feed, respectively. The feeding periods were 4–6 weeks in length. Similarly, eight goat kids of 5–7 weeks of age and 8–14 kg body weight were allotted to either adequate (crude protein 20.1%, feeding period 9–12 weeks) or reduced protein supply (10.1%, feeding period 17–18 weeks). Dietary protein reduction in lambs caused a significant body weight loss of 0.6±0.7 kg, whereas the body weight in control animals increased by 1.9±0.7 kg (P<0.05). Plasma urea concentrations decreased significantly by 60% (low protein 2.3±0.1 versus control 5.7±0.2 mmol l−1, P<0.001). In kids, reduction of dietary protein intake led to significant decreases of the daily weight gain by 48% from 181±8 g to 94±3 g (P<0.001) and daily dry matter intake by 27% from 568±13 g to 417±6 g (P<0.01). Respective urea concentrations in plasma were reduced by 77% from 5.2±0.4 to 1.2±0.2 mmol l−1 (P<0.01). Kinetic analyses of the initial rates of alanine uptake into isolated jejunal brush-border membrane vesicles from sheep and goats as affected by low dietary protein supply yielded that the apparent Km was neither significantly different between the species nor significantly affected by the feeding regime thus ranging between 0.12 and 0.16 mmol.l−1. Reduction of dietary protein, however, resulted in significantly decreased Vmax values of the transport system by 25–30%, irrespective of the species. Kinetic analyses of the initial rates of leucine uptake into jejunal brush-border membrane vesicles from sheep and goats yielded that leucine uptake was mediated by Na+-dependent as well as Na+-independent processes. Similar to alanine, apparent Km values of leucine uptake were neither different between the species nor affected due to low dietary protein and ranged between 0.08 and 0.15 mmol l−1. In contrast to the alanine transport mechanism, dietary protein reduction resulted in increased Vmax values of Na+-dependent leucine transport by 53% in sheep and 230% in goats. Similarly, Na+-independent leucine uptake was stimulated by 85% and 200% in sheep and in goats, respectively. This study shows adaptation of amino acid absorption at the brush-border membrane level of jejunal enterocytes of small ruminants due to dietary protein reduction. Whereas the transport capacity for the nonessential amino acid alanine was reduced due to low dietary protein, the transport capacity for the essential amino acid leucine was markedly stimulated. From this, the involvement of rather different feedback mechanisms in adaptation of intestinal amino acid transport mechanisms has to be discussed.

Bambara groundnut (Vigna subterannea)--a leguminous root nut, which grows in the tropics and subtropics--was used in an experiment to test its effect on the performance of growing broiler chicks. Performance was measured by monitoring growth, measuring nutrients and energy balances and also by determining nutrient accretion. Twelve-day old broiler chicks, kept in individual metabolic cages, were used in an experiment in which birds were equally allotted (n = 10) into a control (fed high performance diet made up principally of wheat and soybean meal) and 6 test groups fed diets containing 19, 76 and 95% raw or autoclaved bambara groundnuts. All diets were similar in energy, nitrogen and total lipid contents. Diets were also balanced for amino acids, vitamins and minerals in accordance to the specific requirements of the birds. Feed and water were provided ad libitum. Growth performance was monitored over 15 days. Nutrient and energy balances were measured by use of TiO2 as marker. The comparative slaughter technique was implored for the determination of energy and nutrient accretion. The results showed that the level of raw or autoclaved bambara had no significant influence on feed intake. Increasing the bambara level in the diets caused a general linear drop in the performance of the broilers. However, with up to 95% bambara in the diet, the general performance was still above 75% compared to the control. Increasing levels of bambara groundnut caused a decrease in the metabolizability of energy and efficiency of utilisation of ME for BWG. The animals retained more water with increasing levels of raw bambara in the diets while autoclaving increased their DM content to levels comparable to the control. The protein composition of gain was comparable at all levels of inclusion. In general autoclaving improved the performance of bambara.

Two groups of breeding sows were fed rations with differing in their respective levels of digestible phosphorus. The two groups received digestible phosphorus levels of about 75 % vs. 100 %, of the recommended level. Two rations were calculated for each group, i.e. for gestation and lactation, respectively, differing between the groups only in further supplementation of monocalciumphosphate. Sows stayed on the same level of digestible phosphorus during the whole trial. Over two years data from 205 or 206 titters per treatment were analysed. No significant difference in sow performance between the two groups occurred. Even long-term analysis of several following litters showed no negative effect of supply of digestible phosphorus at only 75 % of the recommended level on sow performance. In practice there is no need for safety margins in the feeding of breeding sows based on digestible phosphorus. The potential to reduce phosphorus excretion offered from the new evaluation system "digestible phosphorus" should be used in pig breeding.

The effects of increasing dietary levels of crude protein on growth, feed intake, feed efficiency and composition of gain in male Saanen kids were studied. Four groups of four kids each initially weighing 12.1+/-0.18kg and having a weight gain of 195+/-16g/d were penned individually and fed for 73 to 124 days up to 25kg of BW. They were fed chaffed wheat straw (45g CP/kg DM) which had been molasses sprayed (10%) and pelleted concentrates containing 8.7, 11.7, 14.4 and 17.6% crude protein (CP) on DM basis, the ratio of straw to concentrate being 1:5. Kids were fed controlled to satiation in which case small amounts of the feeds were offered about five times a day as long as the kids wanted to eat. Retention of protein, fat and energy were calculated from their initial and final concentrations in the empty body homogenates of the slaughtered kids. With increasing CP level in the diet, feed intake increased from 448 to 608g DM/d, weight gain from 94 to 181g/d, retention of protein from 9.7 to 27.8g/d, retention of fat from 9.6 to 19.1g/d and feed efficiency improved from 4.79 to 3.39kg DM/kg weight gain. Protein composition of gain increased from 103 to 154g/kg BWG while fat (103-105g/kg BWG) remained constant. Regression analyses showed that BWG can be optimized at 136g CP/kg DM and protein retention at 180g CP/kg DM, whereas, dietary nitrogen was utilized most efficiently at 120g CP/kg DM. Extrapolated from the regression equations, maintenance N requirement of the kids at zero N-retention and at zero BWG were 0.38 and 0.16g N/kg W(0.75), respectively. Recommended dietary CP concentrations and maintenance N requirements depend on the traits desired.

Mpe-ineal frorn SI)irulina 1)[atensis harwested froill lake Chad was evaluated as a poultry feed ingredient in an experinient with broiler-chicks. The algae-ineal contained 344 total ash and 423 g crude protein per k- dry rnatter. Arnino'acid composition was analysed and showed a lower con6lentration of lysine, histidine and phenylalanine in proteins of the Spirulina-rneal than in protein of soybeanineal, whereas the other essential arnino acids were present in hiLher concentrations. Four diets A 50, 100 and 150) containina 0, 50, 100 and 150 g algae-ineal per k- diet were fed to inale broiler chick's frorn 6"' to 34t" day of lil'e, Eight birds per treativient were individually housed in cages and fed ad libiturn with free access to water. Feed intake ",as reduced in birds fed diets 100 and t50. Weight gains 1 'ere decreased in birds fed diets 100 and t50 to less than 80% or the control group, Feed intake per weight uain for diets 0. 50 and 100 was within the range of good cornmercial production, birds fed diet 150 consurned sicnificantly rnore feed per unit ",eight gain than birds fed the oth i er dicts. Metabolisability of gross energy of diets was deterinined by calorinietry and HCI-insoluble ash Lis inarken, There was no difference between the 4 diets, which shoals that the ME-concentration in the Spirulinaineal was not inuch different froin the inixture of tnaize, soybearl-ineal, and whcat-starch.

Two concurrent trials were conducted to investigate the influence of low-protein amino acid-supplemented diets on the performance, carcass characteristics, whole-body composition and efficiencies of nutrient utilisation by the male broiler chicken from age 3 to 6 weeks. The first trial comprised five isoenergetic (13.0 MJ kg(-1)) diets containing 225 (control), 210, 190, 172 or 153 g kg(-1) crude protein (CP) supplemented with essential amino acids (EAAs) to meet the minimum National Research Council recommendations. in the second trial a composite mixture of non-essential amino acids (NEAAs) was added to the lower-CP diets (ie 210-153 g kg(-1)) such that they became isoproteinous (N x 6.25) with the 225 g kg(-1) central. Neither the lowering of dietary CP nor NEAA supplementation had any significant influence on weight gain or the relative weights of the various carcass cuts. However, chicks fed the lowest-CP diets consumed more feed (P less than or equal to 0.05) and had poorer (P less than or equal to 0.05) feed conversion efficiency (FCE). NEAA supplementation enhanced FCE to the control levels. Whole-body compositional analysis showed that lowering dietary CP increased (P less than or equal to 0.01) total body fat in a linear fashion (P less than or equal to 0.001; r = -0.72). Equalising dietary GP with the control (ie maintaining identical energy/protein ratio) by NEAA supplementation did not correct for the fat deposition. Total body protein (g kg(-1)) was identical with the control with or without NEAA supplementation. Dietary energy, protein retention efficiency (PRE) and protein efficiency Patio (FER) were more efficient (P less than or equal to 0.01) in the lower-protein diets, while NEAA supplementation significantly (P less than or equal to 0.01) decreased the efficiency of N utilisation. Reducing dietary CP from 225 to 153 g kg(-1) decreased N excretion in a highly significant linear fashion (P less than or equal to 0.001; r = 0.73). The nutritional and environmental implications of the increased body fat deposition on the one hand and the decreased N excretion on the other in the low-protein-fed chickens are discussed and the need to harmonise these apparently conflicting interests is emphasised. (C) 2000 Society of Chemical Industry.

3 Groups of 24 crossbreed heifers intially weighing on average 295 kg were fed rations based on maize silage, soya bean oil and hay until weighing 450 kg. Each heifer was given 50 g daily of an almost Ca- and P-free mineralmix. This mineral feed was given to heifers of group 1 without further supplement, to heifers of group 2 in combination with 50 g ground limestone, and to heifers of group 3 in combination with 100 g ground limestone. Thus, all animals received equal amounts of all nutrients, except Ca. All heifers performed well and showed daily weight gains of about 1000 g, without significant differences in any of the usual performance traits. Neither concentrations of Ca or inorganic P in blood plasma nor concentrations of Ca, P or Mg in the candal vertebra were significantly affected by the level of Ca intake. Relative consumptions of Ca per kg weight gain were 16, 35 and 54 g, respectively. It is concluded that official recommendations for Ca supply during final fattening include large safety margins which could be reduced.

The effect of body weight on P digestibility and on efficacy of supplemental Aspergillus niger phytase was studied in two experiments with young growing pigs. Excreta were collected quantitatively. All diets contained 2.0 g digestible P per kg dry matter at a maximum and renal P excretion never exceeded 15 mg/d. When dietary P mainly originated from monocalcium-phosphate, both P digestibility and Ca net absorption linearly increased by 3.6 and 5.6 percentage units, respectively, when BW increased from 15 to 35 kg. With a similar range in BW, P digestibility and Ca net absorption were unaffected by BW when P mainly originated from maize, barley and soybean meal. In both types of diet, crude protein digestibility increased with increasing body weight, whereas organic matter digestibility was effected by BW only in the diet containing maize, barley and soybean meal. Phytase (400 U/kg) almost doubled P digestibility when supplemented to a diet with P mainly originating from maize, soybean meal and barley. This effect of phytase supplementation was equal in pigs at 15.7 kg BW (33 vs. 55%) and at 39.1 kg BW (32 vs. 56%). Digestibility of any organic fraction was unaffected by supplemental phytase. With regard to on-farm conditions, it appears eligible from this results to apply digestibility coefficients for P determined in growing-finishing pigs for piglets as well.

A balance study was performed in order to quantify the effect of continuously increased phosphorus (P) intake on faecal and urinary P excretion. The aim was to quantify the level of intake where regulatory P excretion becomes relevant for comparative digestibility measurements on P, and when the pig adapts its urinary P excretion to increased P intake. Phosphorus intake of growing pigs was continuously increased on a daily basis starting at a marginal level and P excretion via faeces and urine was continuously followed for 92 days. Two semi-synthetic diets were prepared with different proportions of Na2HPO4 resulting in 2.4 (diet 1) and 6.3 (diet 2) g P/kg DM. Concentration of Ca was adapted to achieve a Ca supply approximately 3.1 fold the digestible P supply. Six castrated male crossbred pigs (31 kg BW) were kept individually in metabolism crates after they had undergone a 14 d P depletion period during which they were fed diet 1 solely. Pigs received 1.04kg of diet 1 per day throughout the experiment, and each day the amount of feed and P supplied to pigs from diet 2 was increased by 12 g and 69 mg, respectively. ME supply was approximately 2.4 fold maintenance and average daily BW gain of pigs during the entire experiment was 690 +/- 30 g. While intake increased linearly, faecal excretion of P and Ca increased non-linearly and could be best described by third order polynomial functions. The proportion of ingested P not excreted via faeces followed a quadratic type of curve with a maximum of 81% at 25 days on experiment and P intake of 4.0 g/d. Thereafter, the proportion decreased continuously. The digestibility of P from diet 2, determined by the slope ratio technique, was constant and not affected by P intake up to a P intake of 5 g/d. Renal P excretion did not exceed inevitable losses until day 60 and increased exponentially thereafter when body P reserves were restored. It is concluded, that an adaptation to surplus P supply occurred earlier on the intestinal than on the renal level. While faecal P excretion appeared regulated depending on the actual requirement for P retention, the regulation via urine depended on the P status of the pig. Once the renal P excretion of growing pigs exceeds a level of 25 mg/d, intake of digestible P cannot be regarded sufficiently low to measure P digestibility as a capacity of the feedstuff.

Of 41 male kids, 14 were killed immediately after birth (3·3 kg BW); the remainder were either fed on goat milk to satiation or weaned at 10 kg BW. After achieving 15·7 kg BW, weaned kids were fed on complete diets including either 20 or 40% straw. Milk-fed kids were slaughtered at 16·8 or 26·7 kg BW, weaned kids at 15·7 or 29–30 kg BW, respectively (at least four kids per treatment). Empty BW as a proportion of final live BW was 0·91±0·02 in milk-fed kids compared to 0·85±0·04 and 0·76±0·04 in kids given complete feeds including 20 or 40% straw, respectively. Empty BW of kids in the heaviest groups were c . 24 kg for milk-fed or weaned kids. Energy and crude protein contents per kg empty BW increased from 4·5 MJ and 158 g in newborn kids to 12·2 MJ and 163 g in milk-fed kids or 10·4 MJ and 194 g in weaned kids, respectively. No influence of the feeding system was found on mineral contents of empty BW. Ca, P and K remained constant at 12·6, 7·7 and 1·9 g/kg, Mg increased from 0·32 to 0·46 g/kg and Na decreased from 2·0 to 1·3 g/kg. Differences in composition of live BW gain are mainly caused by differences in gut-fill. Efficiency of utilization of ME for growth was c . 0·75 in milk-fed kids even at high BW, but only 0·31 in weaned kids. Proportions retained of dietary N, Ca, P, Mg, Na and K were highest in milk-fed kids between birth and 16·8 kg BW: 0·57, 0·88, 0·78, 0·40, 0·37 and 0·10, respectively. They were lowest in kids fed on complete feed including 40% straw from 15·7 to 30·3 kg BW: 0·25, 0·26, 0·32, 0·04, 0·11 and 0·04, respectively. Weaning seems to be of greater influence on composition of BW gain and efficiency of utilization than the increase in empty BW.