Effects on chick growth of adding glycine, proline, glutamic acid or diammonium citrate to diets containing crystalline essential amino acids

Purified diets, designed to supply a balanced sufficiency but not excess of essential amino acids, were supplemented with glycine, glutamic acid, proline or diammonium citrate (DAC) and fed to broiler chicks from the 7 d stage. Slow growth was obtained unless the diet was supplemented with 1 % L‐proline, confirming other work which suggests that proline should be reclassified as an essential amino acid for the chick. Increasing the level of glycine in the diet from 1 ‐o to 1 ‐6% did not result in a marked growth response.

Adding 11–07% DAC to the diet gave a significant growth response and a significant increase in the plasma level of amino acids. The utilisation of DAC was equivalent to that of an isonitrogenous supplement of glutamic acid in one experiment, but was significantly poorer than that of glutamic acid in another.

A significant linear regression of live‐weight gain on nitrogen intake was derived (r = 0–8582): growth was better on a practical than on any of the purified diets used but was in close accordance with this relationship. Partition of the nitrogen intake into intakes of the various nitrogenous components gave more precise correlations. Use of intakes of essential amino acids, DAC, glutamic acid, proline and added glycine explained over 90% of the variance; use of essential amino acids, glutamic acid and proline explained over 83% of the variance.     

Growth of broilers fed on diets containing dried poultry manure

Sixty 7‐d‐old male broiler chicks were housed in individual metabolism cages and offered one of six purified diets for 14 d. The diets were formulated to have the same ME contents but had different nitrogenous supplements: diet A, was the basal diet, containing PRG essential amino acid (EAA) mixture equivalent to 15 g N/kg; B, basal+12% glutamic acid (GA); C, basal plus EAA mixture equivalent to EAA content of 20.09% DPM; D, basal + EAA+12% GA; E, basal + 20.09% autoclaved DPM; F, basal + 20.09% unautoclaved DPM. The rank order of final body weights at 21 d of chicks fed on these diets were D(292 g) > B(258 g), (F254 g), E(253 g) > C(206 g) > A(180 g), (P<0.05). Chicks fed on diet C had better food conversion efficiencies (FCE) than those fed on diet A (0.449 and 0.374 respectively) and D was better than B (0.592 and 0.533 respectively).

In a second experiment, carried out under field trial conditions using commercial‐type diets formulated to contain DPM, 24 groups, each of about 40 male or female broiler chicks, were given diets containing 0% (P) or 5% (Q) DPM from 1 d of age for 4 weeks. From 4 to 8 weeks one of three diets with 0% (R), 5% (S) or 10% (T) DPM was fed according to a 2 (sexes) x 2 x 3 factorial design. Between o and 4 weeks feeding DPM had no significant effect on body weight or food consumption, but birds fed diet Q had an improved FCE (P<0.05). Between 4 and 8 weeks birds fed on S and T were heavier than the controls at 6 weeks, but this increase was not significant at 8 weeks (P> 0.05). Food consumption was not affected, but the FCE improved with increasing inclusion of DPM. At 8 weeks of age birds fed on Q, were heavier than birds fed on diet P.     

The growth of broiler chickens fed low-protein diets containing triammonium citrate, diammonium hydrogen citrate and autoclaved dried poultry manure

Three experiments were carried out using male broiler chicks from 1 to 3 weeks of age. The birds were housed in individual metabolism cages at 1 week of age, having previously been in tiered brooders.

In experiment 1, 36 birds were offered one of six experimental diets based on glucose‐ and cellulose‐diluted commercial broiler mash. The six diets were supplemented with graded levels of triammonium citrate (TAC) at the expense of cellulose such that diet 1B contained no TAC and diet 1F contained 6.4% TAC. In experiment 2, 72 birds were offered one of six diets, similar to those used in experiment 1 with the exception that they were supplemented with graded levels of diammonium hydrogen citrate (DAHC). In experiment 3, 72 birds were offered one of six diets which were based on the same diluted broiler mash but which had been supplemented with graded levels of autoclaved dried poultry manure (ADPM) at the expense of glucose. Diet 3B contained no ADPM whereas diet 3F contained 20% ADPM.

All birds were weighed at 2 and 3 weeks of age and their food consumptions over these periods were recorded. Their growth was compared with that of birds fed the undiluted commercial broiler food.

All birds of experiment 1 (TAC‐supplemented diets) and experiment 2 (DAHC‐supplemented diets) showed significantly poorer growth rates than the control birds. However, birds of experiment 3 (ADPM‐supplemented diets) grew as well as the control birds.     

The effects on egg production and egg composition of adding supplements of amino acids and/or urea or dried auto‐claved poultry manure to a low‐protein layer diet

Thirty‐five laying hens of a medium‐weight hybrid strain, aged 10 months, were given a basal diet containing 11.5% protein or the same diet supplemented with 1.54% essential amino acids and/or with two sources of nitrogen for the synthesis of non‐essential amino acids (1.15% urea or 9.7% dried autoclaved poultry manure) for an 8‐week period.

Egg production, food intake, food conversion efficiency, the gross efficiency of nitrogen conversion and the ability of hens to maintain body weight were improved by supplementation with essential amino acids (P < 0.05 or P < 0.01). Supplementation with dried autoclaved poultry manure raised food intake, total egg mass and mean egg weight (P < 0.05), but supplementation with urea alone did not result in significantly higher egg production, perhaps because it failed to increase food intake. Supplementation with essential amino acids and urea to give the equivalent of 16% protein did not result in significantly higher egg production than that obtained with urea alone. The smallest eggs were produced by hens fed on the diet supplemented with urea, and the largest by those fed on the diet supplemented with dried manure (P < 0.001).

The gross composition of eggs was not influenced significantly by dietary treatment but albumen quality was significantly lower on the basal diet and higher on the supplemented diets (P < 0.001). It was highest in eggs from hens fed on the diet supplemented with urea alone.     

The effects on rearing and subsequent laying performance of rearer diets containing two levels of protein and dried poultry manure or urea

1. Six hundred and seventy‐two light‐hybrid pullets aged 6 weeks were allocated to eight experimental treatments and cage‐reared to 18 weeks of age when they were transferred to single‐bird battery cages and fed on a common layer diet.

2. In the 6‐ to 12‐week period four dietary treatments were applied: a diet containing about 160 g crude protein (CP)/kg with or without 50 g dried poultry manure (DPM)/kg (diets 2 and 1 respectively) and a diet containing about 140 g CP/kg with or without 50 g DPM/kg (diets 4 and 3). In the 12‐ to 18‐week period two additional diets were fed: diets 1 and 3 supplemented with 10 g urea/kg (diets 5 and 6 respectively). Diets containing DPM were formulated to utilise the CP, energy, calcium and 50% of the phosphorus content of DPM.

3. Pullets fed on diets 1, 2 and 5 (high‐protein) were significantly heavier at 18 weeks than those fed on diets 3, 4 and 6 (low‐protein). In the laying period total estimated egg weight, food intake and conversion were significantly greater, and the age at first egg was significantly less (2.4 d).

4. Dietary DPM had no significant effect on the 18‐week body weight but food consumption was significantly less and conversion was significantly improved. There were no significant effects on subsequent laying performance. Dietary urea caused no significant effects on rearing or laying performance.     

Effects of battery gage shape and dietary energy regulation on the performance of laying hens offered diets containing dried poultry manure

1. About 3000 medium‐weight hybrid chicks were used in a factorial experiment involving two “chick” treatments: diets containing 0 and 50 g dried poultry manure (DPM)/kg; three “grower” treatments, diets with and without 50 g DPM/kg given ad libitum and regulated amounts of the diet with DPM; five “layer” treatments: diets with 0, 100 or 200 g DPM/kg given ad libitum and regulated amounts of diets containing 110 and 220 g DPM/kg and two shapes of layer cages: deep (conventional) and shallow.

2. Chick diets had no significant effects on rearing or subsequent laying performance.

3. Food‐regulated pullets were 7% lighter than pullets given the DPM diet ad libitum at 18 weeks but consumed 12.5% less food; growing treatments had no significant effect on subsequent egg production.

4. Hens housed in shallow cages laid 10.3 eggs/bird‐housed more than those in deep cages, produced 3.8% greater egg mass, consumed 2.7% less food and produced fewer damaged (cracked, broken and hair‐cracked) eggs (P< 0.001).

5. DPM‐containing layer diets had no adverse effects on egg production, or mortality; with 100 g DPM/kg efficiency of food conversion (EFC) was better than with 0 or 200 g/kg (P< 0.001).

6. Reduction of the energy intake of L110R and L220R hens with diets containing 110 and 220 g DPM/kg by 8.2 and 9.0% respectively, reduced the number of eggs laid/hen‐housed by 6 and 10.7 but improved the EFG (P< 0.001); there was no significant interaction between cage shape and energy regulation.     

Effects of adding fiber sources to reduced-crude protein,amino acid-supplemented diets on nitrogen excretion,growth performance,and carcass traits of finishing pigs

Two experiments were conducted to evaluate the effects of adding fiber sources to reduced-crude protein (CP), amino acid-supplemented diets on N excretion, growth performance, and carcass traits of growing-finishing pigs. In Exp. 1, six sets of four littermate barrows (initial weight = 36.3 kg) were allotted randomly to four dietary treatments to determine N balance and slurry composition. Dietary treatments were: 1) fortified corn-soybean meal, control, 2) as fortified corn-soybean meal with CP lowered by 4 percentage units and supplemented with lysine, threonine, methionine, tryptophan, isoleucine, and valine (LPAA), 3) same as Diet 2 plus 10% soybean hulls, and 4) same as Diet 2 with 10% dried beet pulp. Nitrogen intake, absorption, and retention (g/d) were reduced (P < 0.04) in pigs fed the low- protein diets, but they were not affected (P > 0.10) by addition of fiber sources to the LPAA diet. However, N absorption, as a percentage of intake, was not affected (P > 0.10) by dietary treatment. Nitrogen retention, expressed as a percentage of N intake, was increased (P < 0.02) in pigs fed the low-protein diets, but it was not affected by fiber addition to the LPAA diet. Urinary and total N excretion was reduced (P < 0.01) by 50 and 40%, respectively, in pigs fed the low- protein diets, but it was not affected (P > 0.10) by fiber addition. However, fiber addition to the LPAA diet tended to result in a greater proportion of N excreted in the feces than in the urine. Slurry pH, ammonium N content, and urinary urea N excretion were reduced (P < 0.10) in pigs fed LPAA, and a further reduction (P < 0.06) in slurry ammonium N content and urinary urea N was observed with fiber addition. Also, fiber addition to the LPAA diet increased (P < 0.02) slurry VFA concentrations. In Exp. 2, 72 pigs were blocked by body weight and sex and allotted randomly to three dietary treatments that were similar to those in Exp. 1, with a corn-soybean meal control diet, LPAA diet, and a LPAA diet with 10% soybean hulls. Pigs were fed the diets from 28.6 to 115 kg, and all pigs were killed for collection of carcass data. Growth performance and most carcass traits were not affected (P > 0.10) by dietary treatment. These data suggest that reducing CP with amino acid supplementation markedly decreased N excretion without influencing growth performance. Fiber addition to a LPAA diet had little effect on overall N balance or growth performance, but tended to further reduce slurry ammonium N concentration and increase volatile fatty acid concentrations.     

The laying performance of two strains of hens offered diets containing dried poultry manure during the laying stage

1. Light‐weight (Babcock B300) and medium‐weight (Warren‐SSL) hens were offered diets, containing 0, 100 or 200 g dried poultry manure (DPM) and 11.49, 11.12 or 10.83 MJ metabolisable energy/kg respectively, between 18 and 70 weeks of age. The true protein, metabolisable energy, calcium and phosphorus contents of the DPM, from caged layer hens, were used in the diet formulation.

2. The hen‐housed laying performance of hens offered the DPM‐containing diets was significantly better for number of eggs laid and total egg mass produced but the performance of the control groups was lower than would normally be expected of those stocks. The reason for the lower rate of lay and higher mortality of hens fed on the control diet was not identified. The amount of food consumed increased as the energy content of the diet decreased and the efficiency of food conversion (EFC) of the lightweight strain was reduced; there was no significant effect on the EFC of the medium‐weight hens.

3. The inclusion of DPM in the diets had no effect on albumen quality or on the incidence of hair‐cracked, cracked or broken eggs. However, with both strains of hens, shell weight and shell thickness were poorer when 100 or 200 g DPM/kg diets were fed.     

The effect of carbohydrate source and energy-to-amino acid ratio on the growth of chicks given diets containing crystalline amino acids

In each of two experiments chicks aged 7 d were housed individually and given purified diets containing crystalline amino acids for a period of 13 or 14 d.

In the first experiment a comparison was made of four amino acid mixtures and of starch plus sucrose as a carbohydrate source. It was found that an amino acid mixture formulated on the basis of current recommendations for overall amino acid balance and for the high ME value of purified diets (diet G), gave superior growth and efficiency of food conversion. The amount of food eaten was greater with diets containing starch plus sucrose than with starch alone and as a result growth was improved. Carbohydrate source had no significant influence on the efficiency of food conversion.

In the second experiment diet G was modified by reducing the level of ME with a concomitant reduction in the level of all amino acids. The effect of modifying a comparable diet developed at the University of Illinois by lowering the ME level while keeping the level of all amino acids constant was also tested. It was found that diet G modified by the incorporation of 10% extracted sawdust gave the best growth performance and it is suggested as an amino acid reference diet. The growth rate achieved with it was 16 g/d from 7 to 14 d which surpassed that obtained with a practical broiler diet. Modification of the Illinois diet did not improve the growth performance.     

Effect of glycine supplementation in low protein diets with amino acids from soy protein isolate or free amino acids on broiler growth and nitrogen utilisation

1. Here, it was investigated whether substitution of amino acids (AA) from soy protein isolate with free AA in low crude protein diets influences the growth performance and N utilisation in broilers, and whether interactions with dietary glycine equivalent (Gly_equi) concentration exist.

2. Birds were distributed in two 2 × 2 factorial arrangements of 48 floor pens containing 10 birds each, plus 48 metabolism cages containing two birds each. Experimental feed was provided for ad libitum consumption from d 7 to 22. Diets contained either a soy protein isolate at 79 g/kg or a mix of free AA, which supplied the same amount of 18 proteinogenic AA. A mix of free glycine and l-serine was used to obtain low and high (12.0 and 20.5 g/kg dry matter) levels of dietary Gly_equi.

3. Substitution of soy protein isolate with free AA reduced the average daily gain and feed efficiency, mainly due to reduced feed intake. Efficiency of N accretion was not influenced by the AA source or Gly_equi concentration on d 21, possibly due to the lower AA digestibility of soy protein isolate and higher urinary excretion of nitrogenous substances in the treatments with the AA mix.

4. The average daily weight gain of the treatments with high Gly_equi concentration was higher for both AA sources. This increase was due to higher average daily feed intake by broilers in the treatments with soy protein isolate and due to the increased feed efficiency in the treatments with the AA mix. Broilers exhibited different growth responses to dietary Gly_equi between the AA sources; however, these responses could not be attributed to the different utilisation of Gly_equi for uric acid synthesis.

     

低蛋白补充合成氨基酸日粮对仔猪氮排泄的影响

试验选用32头断奶仔猪,初始体重为6.8kg,共进行14d,其中适应期9d,正式收粪尿期为5d。试验全面研究了不同蛋白水平补充合成氨基酸对仔猪氮排泄的影响。研究发现,降低蛋白水平并按照理想蛋白模式补充合成氨基酸,显著降低了粪尿排放量(P=0.01),线性降低了氮排泄(P<0.001),同时日氮沉积绝对量也呈现线性下降(P<0.001);平均每降低一个百分点的仔猪日粮蛋白水平,可减少8.4%的氮排泄量。     

The fate of recycled urate in hens fed on a diet containing dried poultry manure.

1. Seven colostomised hens were fed on a control diet free of dried poultry manure (DPM) or one including 20% DPM. 2. Urate excretion was greater during DPM feeding by approximately the amount consumed: little urate was present in faeces. 3. Doses of 10-6 muCi of 14C-urate introduced into the crop were quantitatively excreted in the urine within 24 h. 4. The results show that none of the urate present in DPM is utilised by the laying hen.     

Effects of crystalline amino acid supplementation to the diet on odor from pig manure

The objective of this study was to determine the effects of specific crystalline AA supplementation to a diet on odor emission, odor intensity, odor hedonic tone, and ammonia emission from pig manure, and on manure characteristics (pH; ammonia N; total nitrogen; sulfurous, indolic, and phenolic compounds; and VFA concentrations). An experiment was conducted with growing pigs (n = 18) in a randomized complete block design, with 3 treatments in 6 blocks. Treatment groups were (1) a 15%-CP basal diet with 3 times the requirement of sulfur-containing AA (14.2 g/kg of diet, as-fed basis); (2) the basal diet with 2 times the requirement of Trp and Phe+Tyr (2.9 and 20.4 g/kg of diet, respectively, as-fed basis); and (3) the basal diet with AA supplementation to levels sufficient for maximum protein gain. Pigs with an initial BW of 41.2 +/- 0.8 kg were individually penned in partly slatted floor pens and offered a daily feed allowance of 2.8 times the maintenance requirement for NE (293 kJ/kg of BW(0.75)). Feed was mixed with water at 1:2.5 (wt/wt). Feces and urine of each pig was allowed to accumulate in separate manure pits under the slatted floor. After an adaptation period of 2 wk, and after cleaning the manure pits, manure was subsequently collected. In wk 5 of the collection period, separate samples were collected directly from each manure pit for odor, ammonia, and manure composition analyses. Air samples were analyzed for odor concentration and for hedonic tone and odor intensity above the odor detection threshold. Results showed that supplementing crystalline S-containing AA in surplus of the requirement increased odor emission (P < 0.001) and odor intensity (P < 0.05) and reduced odor hedonic tone (P < 0.05) from the air above the manure pits. Supplementing crystalline Trp, Tyr, and Phe in surplus of the recommended requirements did not affect odor emission, odor intensity, or odor hedonic tone. Regardless of dietary treatment, all pigs had similar performance levels. No differences were observed in ammonia emission from manure of pigs fed different levels of AA supplementation (P = 0.20). To reduce odor from pig manure, dietary S-containing AA should be minimized to just meet the recommended requirements.     

日粮由添加甘露寡糖和香精油对仔猪生长性能的影响

本试验目的是研究日粮中添加甘露寡糖和香精油替代抗生素对仔猪生产指标的影响.25窝个体均匀的仔猪被随机分配到5个试验组中,每组50～60只.仔猪在30日龄断奶,在仔猪断奶前2d开始给仔猪饲喂教槽料,并持续饲喂39d.试验组(Ⅰ组)仔猪采食的日粮不含抗生素,试验组(Ⅱ组)仔猪采食含抗生素多黏菌素E(120mg/kg)的日粮,试验组(Ⅲ、Ⅳ、Ⅴ组)仔猪采食含添加剂(甘露寡糖和香精油)的日粮,其中,断奶前每吨日粮中分别添加4、5和6kg的添加剂(甘露寡糖和香精油),断奶后每吨日粮中分别添加2、3和4kg的添加剂(甘露寡糖和香精油).在整个试验阶段对试验仔猪的体重、日增重、采食量和饲料转化率等指标进行了测定,并着重观测了仔猪的健康状况和死亡率等指标.本试验结果表明,当日粮中不添加抗生素时,哺乳仔猪的生产指标显著下降.日粮中添加4kg/t的甘露寡糖和香精油来替代抗生素时能相对保持仔猪的体重和日增重,并能降低哺乳仔猪的死亡率.     

Enzyme studies with the livers of chicks fed semi‐synthetic diets containing crystalline amino acids and diammonium citrate

The levels of glutamate dehydrogenase [NAD(P)], (GDH), aspartate trans‐aminase (AspT) and alanine transaminase (AlT) were measured in livers from chicks fed on a semi‐synthetic diet containing crystalline essential amino acids as the sole nitrogen source (diet A). The effects of a supplement of 12.0% glutamic acid (diet H) or 11.07% diammonium citrate (DAC) (diet B) or 12.0% glutamic acid plus 1.0% proline with an additional 0.6% glycine (diet C) on these enzymes were studied and the results compared with the levels found for control chicks given a typical diet based on cereal protein (diet J). The abilities of livers from chicks given diets A, B and C to synthesise [14C] glutamic acid from [14C]2‐oxoglutaric acid and diammonium citrate (DAC) were assessed.

The levels of GDH, AspT and AlT found in the livers of chicks given the control diet were 54.1, 966 and 123.7 units/mg protein respectively. Non‐essential nitrogen added as glutamic acid or as DAC did not cause induction of the enzymes studied above control levels. Glutamic acid (diets H and B) caused a depression of GDH levels (37.4 and 38.9 units/mg protein respectively) but had no effect on AspT and AlT compared with the controls, whereas DAC caused a decrease in AlT (43.9 units/mg protein) but had no effect on AspT and GDH; diet A depressed AlT and AspT levels (64.4 and 735 units/mg protein respectively).

The livers of chicks given diets A, C and B varied in their ability to synthesise glutamic acid, 39.3%, 31.9% and 24.0% respectively of the radioactivity being recovered as glutamic acid.     

液态或颗粒饲料添加精氨酸对21～42 d断奶仔猪生长性能和血浆氨基酸水平的影响

文章旨在研究饲喂颗粒料或液态料以及日粮添加精氨酸对断奶仔猪生长性能及血浆必需氨基酸和非必需氨基酸含量的影响。试验选择21 d断奶的健康仔猪672头,随机分为4组,每组6个重复,每个重复28头。试验日粮采用2×2多因素方差设计,2种饲料形态(液态料或颗粒料),2个精氨酸水平(0或6 g/kg精氨酸),试验共进行21 d。断奶后前10 d饲喂液态料较颗粒料显著改善了仔猪的平均日采食量、平均日增重和料比(P<0.05);在断奶后第11~13天液态料向颗粒料过渡阶段,液态料组较颗粒料组对日增重和料比具有负面影响(P<0.05);饲料形态和添加精氨酸以及饲料形态和仔猪日龄对断奶仔猪的平均日采食量的影响具有显著交互效应(P<0.05)。断奶后前10 d,饲喂液态料的仔猪较颗粒显著提高了干物质摄入量(P<0.05);断奶后前10 d饲喂添加精氨酸的液态料仔猪,由液态料向固体料过渡,显著提高了采食量和日增重(P<0.05)。液态或颗粒饲料添加精氨酸显著降低了断奶仔猪血浆尿素氮含量(P<0.05);饲喂液态料的断奶仔猪在28和37 d较颗粒料组显著降低了血浆尿素氮含量(P<0.05)。除了色氨酸、组氨酸、谷氨酸和甘氨酸外,液态料较颗粒料均显著提高了断奶仔猪血浆氨基酸水平(P<0.05);颗粒料或液态料添加精氨酸显著提高了断奶仔猪血浆亮氨酸、异亮氨酸、精氨酸和甘氨酸水平(P<0.05)。综上所述,断奶后仔猪饲喂液态料可以提高生长性能,但无论颗粒料还是液态料添加精氨酸均可以显著提高血浆精氨酸水平,降低尿素氮含量。     

Influence of the ratio of essential to non essential amino acids on performance and carcase composition of the broiler chick

Male broilers were fed on isocaloric diets containing 140, 180 or 220 g/kg crude protein from 1 to 3 weeks of age. Four diets were formulated for each protein concentration so that essential amino acids (EAA), all balanced in proportion to requirement, supplied 350, 450, 550 or 650 g/kg crude protein. Weight gain, efficiency of food utilisation and total carcase protein reached plateaux at 550 g EAA/kg protein irrespective of the dietary protein content, whereas the proportion of carcase fat decreased and that of carcase protein increased as the proportion of EAA in the dietary protein increased. All EAA in the diet containing 550 g EAA/kg protein were supplied at 125% of requirement, suggesting that the amino acid requirements as reported are inaccurate. Weight gain and carcase protein were shown to be significantly (P less than 0.001) dependent on total intake of EAA rather than on the proportion of EAA in the diet per se. In order to supply sufficient EAA for maximum gains, the diet had to contain more than 140 g crude protein/kg and 450 g EAA/kg protein.     

Effects on performance of growing pigs fed diets containing different levels of dried cashew pulp

The purpose was to investigate the use of dried cashew pulp (DrCP), the sun-dried residue after juice has been extracted from the cashew apple, as a feed ingredient in growing pig diets. The growth rate, feed intake, feed to gain ratio and cost of gain of grower pigs fed diets containing 0 (0DrCP), 100 (100DrCP), 150 (150DrCP) or 200 (200DrCP) g kg⁻¹ of dried cashew pulp was investigated in a feeding trial set up as a Completely randomized design with 4 treatments replicated 3 times and lasting 112 days. There were no significant differences (P > 0.05) among treatments in the parameters measured. It was concluded that dried cashew pulp could be used in growing pig diets up to a level of 200 g kg⁻¹ without any deleterious effects. Future work will look at higher levels of DrCP inclusion in the diets of growing pigs.