Dietary Crude Protein Reduction Research Articles

Effect of Dietary Crude Protein Reduction Levels on Performance, Nutrient Digestibility, Nitrogen Utilization, Blood Parameters, Meat Quality, and Welfare Index of Broilers in Welfare-Friendly Environments

We investigated the effects of feeding different levels of crude protein (CP) on broiler performance, blood characteristics, meat quality, nutrient and nitrogen (N) availability, stress levels, and welfare indicators in a welfare environment. A total of 625 eight-day-old male broilers were assigned to five dietary CP levels (control (CON) and 1–4% CP reductions) during the grower (8–21 days) and finisher (22–35 days) periods. The CON diet contained 20% CP in the grower phase and 19% in the finisher phase, while all birds received a 22% CP diet during the starter period (1–7 days). Intriguingly, reducing CP levels in the diet did not significantly affect growth performance. These results may be due to the adequate supplementation of essential amino acids in the diets of all treatments and the compensatory growth observed in the finisher phase. Low-CP diets reduced CP digestibility, N intake, and N excretion, while N retention efficiency improved (p < 0.001). Serum total protein (TP) levels decreased equally with decreasing CP in the diet, and the crude fat content in meat increased linearly (p < 0.01). The litter moisture content and pH decreased with lower CP levels, and the welfare indices (footpad dermatitis (FPD), serum corticosterone, etc.) improved (p < 0.01). In conclusion, an appropriate reduction in CP levels in their diet can enhance broiler welfare by reducing N excretion and improving litter quality without adversely affecting performance.

Productive, Physiological, and Environmental Implications of Reducing Crude Protein Content in Swine Diets: A Review

Pig production is one of the most important providers of high-quality proteins and amino acids (AAs) to human nutrition. In this sector, feeding has an important economic and environmental impact. A strategy to reduce production costs and negative sustainability effects is reducing dietary crude protein (CP) contents with or without AA supplementation. This review addresses the different aspects related to this strategy, particularly the effects on growth performance and pork traits in piglets and growing and finishing pigs, as well as the physiological molecular mechanisms’ underlying effects. Insight is also provided into the effects of dietary CP reduction on the productive performances of alternative pig production systems and breeding boars and sows. Finally, an overview is conducted on the effects of dietary CP reduction on ammonia, odor, and greenhouse gas emissions arising from pig production systems. Overall, CP reduction may lead to production losses, albeit they can be, to some extent, hindered by adequate AA supplementation. Losses are particularly relevant during the post-weaning phase, whereas in finishing pigs, it may bring additional benefits, such as high intramuscular fat contents in some markets or improved gut barrier function with benefits to the animals’ health and welfare, as well as decreased ammonia emissions to the environment.

Assessment of two diet types in reduced-crude protein diets with or without phytase supplementation – implications on key phenotypic responses in 21-day-old broiler chickens

ABSTRACT 1. Two concurrent experiments were conducted to investigate the effect of using the crude protein (CP) value of supplemental amino acids (AA) in formulating reduced-crude protein (RCP) diets. The RCP diets formulated without accounting for CP values of supplemental AA (RCPN) or otherwise (RCPY) or a positive control (PC) diet were fed without (Experiment 1) or with (Experiment 2) phytase. 2. Each experiment utilised 105 male broiler chicks. Birds were provided a common starter diet from d 0–7. On d 21, ileal digesta were collected from the distal half of the ileum. For mRNA expression analysis, tissues were collected from the mid-jejunum and the liver. Excreta grab samples were collected for analysis for N content. 3. In Experiment 1, there was a stepwise decrease (p < 0.01) in weight gain and excreta N for birds receiving PC, RCPN and RCPY diets. The coefficients of ileal digestibility of His, Leu, Phe and Trp were greater (p < 0.05) in birds that received RCPY rather than the PC diets. The relative mRNA expression of CAT1 was greater (p < 0.05) for birds that received the PC diet. 4. In Experiment 2, growth performance and excreta N were not different between the PC and RCPN diets, but weight gain, feed intake and excreta N were greater (p < 0.01) in birds receiving PC or RCPN diets. The coefficients of digestibility were greater (p < 0.01) in RCP than PC diets for Lys, Thr, Cys, Gly and Ser. The mRNA expression for S6kinase and PRKAβ2 was greater (p < 0.05) for birds fed RCPN compared to PC. 5. In conclusion, accounting for the N content of supplemental AA during feed formulation for RCP diets will influence the effect of CP reduction on growth performance and ileal amino acid digestibility.

Growth performance of pigs fed low-protein diets supplemented with crystalline amino acids at different growth stages.

This study aimed to investigate the impact of reducing dietary crude protein (CP) coupled with supplementation of indispensable amino acids (AA) on growth performance of pigs at different growth stages. A total of 126 (63 barrows and 63 gilts), 90 (45 barrows and gilts), and 72 (36 barrows and 36 gilts) pigs with average weights of 9.8 ± 1.62, 30.6 ± 2.31, and 58.3 ± 2.95 kg in the nursery, growing, and finishing stages, respectively, were assigned to three dietary treatments with six replicates in a randomized complete block design. The pigs had ad libitum access to water and fed three experimental diets, each supplemented with all indispensable AA and subjected to a 2% reduction in CP from the upper limits of 18%, 16%, and 16% established for the nursery, growing, and finishing stages, respectively. In the nursery stage, from 0 to 2 weeks, reducing dietary CP concentrations decreased average daily feed intake (ADFI; linear, p = 0.04). From 2 to 4 weeks, dietary CP reduction decreased average daily gain (ADG; linear, p < 0.01; quadratic, p = 0.02), ADFI (linear, p = 0.04), and gain-to-feed ratio (G:F; linear, p = 0.01). From 0 to 4 weeks, reduction in dietary CP concentrations decreased ADG (linear p < 0.01), and G:F (linear, p = 0.01). In the growing stage, the dietary CP reduction did not affect growth performance. During the finishing stage, decrease in dietary CP concentrations decreased ADFI from 3 to 6 weeks (quadratic, p < 0.01) and 0 to 6 weeks (quadratic, p = 0.01). Dietary CP reduction with indispensable AA supplementation potentially decreases the growth performance of nursery pigs but may not decrease the growth performance of growing and finishing pigs.

Dietary Crude Protein Reduction with Addition of Crystalline Amino Acids in Growing Pekin Ducks Housed in Cascading Cages: Influence on Growth Performance, Carcass Traits, and Apparent Nutrient Digestibility

The intensive raising model for meat duck production has widely adopted cascading cages. However, investigations on low-protein diets for Pekin ducks under this model are scarce. Thus, a 3 × 6 factorial experiment was conducted using six dietary crude protein (CP) levels (17.61%, 16.25%, 15.34%, 14.55%, 13.38%, and 12.64%, analyzed) and three cage layers (lower, middle, and upper). The study aimed to examine the effects of dietary CP reduction with crystalline amino acid supplementation on growth performance, carcass traits, and apparent nutrient digestibility in growing Pekin ducks from 21 to 42 days of age housed at different cage layers. A total of 1620 21-day-old Pekin ducks were randomly divided into 18 groups, each with six replicates of 15 ducks per replicate. Ducks were distributed across different cage layers and were fed one of six experimental diets, respectively, each varying in dietary CP levels but maintaining similar dietary energy and amino acid profiles. The results showed that the reduction in dietary CP levels affected growth performance (p &lt; 0.05), while weight gain, feed intake, and feed/gain of Pekin ducks had no difference among 17.61%, 16.25%, and 15.34% CP groups (p &gt; 0.05). As dietary CP decreased, abdominal fat yield increased (p &lt; 0.05), but breast and leg meat yields were unaffected (p &gt; 0.05). CP intake, nitrogen intake, and nitrogen excretion decreased linearly (p &lt; 0.05) with decreasing dietary CP levels, while apparent nutrient digestibility in Pekin ducks increased proportionally (p &lt; 0.05). Additionally, body weight, weight gain, feed intake, CP intake, nitrogen intake, and nitrogen excretion of Pekin ducks decreased (p &lt; 0.05) due to different cage layers, while carcass characteristics remained unaffected by cage layer (p &gt; 0.05). In summary, it is feasible to reduce the dietary CP level with crystalline amino acid supplementation in growing Pekin ducks from 21 to 42 days of age housed in cascading cages, while the cage layers affected growth performance of ducks. Based on broken-line models, it was determined that the optimal dietary CP requirement for achieving maximum weight gain and feed efficiency in growing Pekin ducks is approximately 15%.

A reduction in dietary crude protein with amino acid balance has no negative effects in pigs.

The aim of this experiment was to evaluate the effects of low crude protein (CP) level with essential amino acids (AA) addition on growth performance, nutrient digestibility, microbiota, and volatile fatty acid composition in growing pigs. A total of 160 growing pigs (Landrace × Yorkshire × Duroc [LYD]; average initial body weight 16.68 ± 0.12 kg) were randomly allotted to one of the four treatments on the basis of initial body weight. A randomized complete block design was used to conduct this experiment in the Research Center of Animal Life Sciences at Kangwon National University. There were ten pigs/replicate with four replicates in each treatment. The treatments include; CON (Control, 17.2% dietary CP level), low protein (LP)-1.10 (15.7% dietary CP level + 1.10% lysine level), LP-1.15 (15.7% dietary CP level + 1.15% lysine level), LP1.2 (15.7% dietary CP level + 1.20% lysine level). The pigs fed CON and LP-1.2 diet showed greater final body weight than that of LP-1.1 diet (p < 0.05). Although average daily gain, average daily feed intake, and feed efficiency did not show any difference in phase 2 and 3, average daily gain and feed efficiency was significantly greater in CON and LP-1.20 in phase 1. However, the average daily feed intake did not show any difference during the experimental period. Isobutyric acid and isovaleric acid composition of LP treatments were lower than CON treatment in phase 2. Total branched chain fatty acid composition was significantly lower in LP treatment in phases 1 and 2. However, there was no significant difference among treatments in phase 3. The results of this study underscore the importance of AA supplementation when implementing a low-protein diet during the early growth phase (16-50 kg) in pigs.

Low crude protein formulation with supplemental amino acids for its impacts on intestinal health and growth performance of growing-finishing pigs

Background Low crude protein (CP) formulations with supplemental amino acids (AA) are used to enhance intestinal health, reduce costs, minimize environmental impact, and maintain growth performance of pigs. However, extensive reduction of dietary CP can compromise growth performance due to limited synthesis of non-essential AA and limited availability of bioactive compounds from protein supplements even when AA requirements are met. Moreover, implementing a low CP formulation can increase the net energy (NE) content in feeds causing excessive fat deposition. Additional supplementation of functional AA, coupled with low CP formulation could further enhance intestinal health and glucose metabolism, improving nitrogen utilization, and growth performance. Three experiments were conducted to evaluate the effects of low CP formulations with supplemental AA on the intestinal health and growth performance of growing-finishing pigs.Methods In Exp. 1, 90 pigs (19.7 ± 1.1 kg, 45 barrows and 45 gilts) were assigned to 3 treatments: CON (18.0% CP, supplementing Lys, Met, and Thr), LCP (16.0% CP, supplementing Lys, Met, Thr, Trp, and Val), and LCPT (16.1% CP, LCP + 0.05% SID Trp). In Exp. 2, 72 pigs (34.2 ± 4.2 kg BW) were assigned to 3 treatments: CON (17.7% CP, meeting the requirements of Lys, Met, Thr, and Trp); LCP (15.0% CP, meeting Lys, Thr, Trp, Met, Val, Ile, and Phe); and VLCP (12.8% CP, meeting Lys, Thr, Trp, Met, Val, Ile, Phe, His, and Leu). In Exp. 3, 72 pigs (54.1 ± 5.9 kg BW) were assigned to 3 treatments and fed experimental diets for 3 phases (grower 2, finishing 1, and finishing 2). Treatments were CON (18.0%, 13.8%, 12.7% CP for 3 phases; meeting Lys, Met, Thr, and Trp); LCP (13.5%, 11.4%, 10.4% CP for 3 phases; meeting Lys, Thr, Trp, Met, Val, Ile, and Phe); and LCPG (14.1%, 12.8%, 11.1% CP for 3 phases; LCP + Glu to match SID Glu with CON). All diets had 2.6 Mcal/kg NE.ResultsIn Exp. 1, overall, the growth performance did not differ among treatments. The LCPT increased (P < 0.05) Claudin-1 expression in the duodenum and jejunum. The LCP and LCPT increased (P < 0.05) CAT-1, 4F2hc, and B0AT expressions in the jejunum. In Exp. 2, overall, the VLCP reduced (P < 0.05) G:F and BUN. The LCP and VLCP increased (P < 0.05) the backfat thickness (BFT). In Exp. 3, overall, growth performance and BFT did not differ among treatments. The LCPG reduced (P < 0.05) BUN, whereas increased the insulin in plasma. The LCP and LCPG reduced (P < 0.05) the abundance of Streptococcaceae, whereas the LCP reduced (P < 0.05) Erysipelotrichaceae, and the alpha diversity.ConclusionsWhen implementing low CP formulation, CP can be reduced by supplementation of Lys, Thr, Met, Trp, Val, and Ile without affecting the growth performance of growing-finishing pigs when NE is adjusted to avoid increased fat deposition. Supplementation of Trp above the requirement or supplementation of Glu in low CP formulation seems to benefit intestinal health as well as improved nitrogen utilization and glucose metabolism.

Effects of reduced crude protein diets while maintaining essential amino acid concentrations on growth performance, nitrogen output, ammonia production, and meat yield

An experiment was conducted to determine the effect of feeding reduced crude protein (CP) diets to Ross × Ross 708 male broilers while providing adequate essential amino acid (AA) concentrations on growth performance, nitrogen (N) and ammonia output, and carcass characteristics from d 1 to 33 post hatch. Birds received 1 of 6 dietary treatments (10 replicate pens per treatment) varying in CP content. Diet 1 (control) was formulated with DL-Met, L-Lys, and L-Thr (23.2, 20.7, and 19.1% CP) in the starter (1-14 d of age), grower (15-25 d of age), and finisher (26-33 d of age) periods, respectively. Dietary L-Val, Gly (only in starter period), L-Ile, L-Arg, and L-Trp were sequentially supplemented in the order of limitation in Diets 2 through 6. Dietary CP was reduced gradually across the dietary treatments resulting in a CP reduction in Diets 1 to 6 by 3.4, 3.4, and 2.3% points in the starter, grower, and finisher periods, respectively. At d 14, 25, and 33 posthatch, feed conversion decreased (P < 0.05) with L-Val addition (Diet 2) and increased (P < 0.01) with L-Val to L-Trp addition (Diet 6) to the control. Dietary treatments did not alter weights and yields of carcass, breast, drum, or thighs. Dietary CP reduction with added L-Val (Diet 2), L-Val to L-Arg (Diet 5), or L-Val to L-Trp (Diet 6) increased abdominal fat (P < 0.01) compared with control. Nitrogen excretion (g/bird; P = 0.003) and equilibrium ammonia concentration (mg/kg; P = 0.041) at day 33 reduced by 16% and 48% respectively in birds fed reduced-CP diets with L-Val to L-Trp (Diet 6) compared with control-fed birds. This study indicated that sequential addition of supplemental AA in the order of limitation from DL-Met to L-Arg allowed reduction of dietary CP beyond 2%-point without depressing growth performance and meat yield of broilers from day 1 to 33 while reducing nitrogen excretion and ammonia emissions.

Apparent ileal amino acid digestibility, gut morphometrics, and gene expression of peptide and amino acid transporters in broiler chickens fed low-crude-protein diets supplemented with crystalline amino acids with soybean meal, canola meal, or corn DDGS as protein feedstuffs.

We investigated the impact of using canola meal (CM) or corn distillers dried grain soluble (cDDGS) in place of soybean meal (SBM) in low-crude-protein diets supplemented with amino acids (AA) on AA digestibility, gut morphometrics, and AA transporter genes in broiler chicken. On day 0, 540 Cobb 500 male broilers were allocated to six diets in 36-floor pens. The positive control (PC) was a corn-SBM diet with adequate crude protein (CP). The CP level of negative control (NC) was decreased by 45 and 40 g kg-1 relative to PC for grower and finisher phases, respectively. The subsequent two diets had the same CP levels as NC but with cDDGS added at 50 or 125 g kg-1. The last two diets had the same CP as NC but with CM added at 50 or 100 g kg-1. Dietary CP reduction in corn-SBM diets increased (P < 0.05) the digestibility of Lys (88.5%), Met (90.7%), Thr (77.4%), Cys (80.7%), and Gly (84.7%). Increasing levels of cDDGS linearly decreased (P < 0.05) the digestibility of Asp, Cys, Glu, and Ser, whereas increasing CM level linearly decreased (P < 0.05) the digestibility of Cys, Pro, and Ser. The CP reduction in corn-SBM diets produced downward expression of peptide transporter1 and decreased (P < 0.05) absolute pancreas and ileum weight and length of jejunum and ileum. Partial replacement of SBM with alternative protein feedstuffs (cDDGS or CM) in low-CP diets had minimal effects on AA digestibility and mRNA levels of peptides and AA transporters. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Reducing dietary crude protein: Effects on digestibility, nitrogen balance, and blood metabolites in late-lactation Holstein cows

Our objectives were to determine the effects of reducing dietary crude protein (CP) concentration on nutrient digestibility, rumen function, N balance, and serum AA concentration for dairy cows in late lactation. At the initiation of the experimental period, we stratified Holstein cows (n = 128; mean ± standard deviation 224 ± 54 d in milk) by parity and days pregnant (86 ± 25 d) and assigned them to 1 of 16 pens. For 3 wk, all cows received a covariate diet containing 16.9% CP [dry matter (DM) basis]. For the subsequent 12 wk, we assigned pens to 1 of 4 treatments containing 16.2, 14.4, 13.4, or 11.9% CP (DM basis) in a randomized complete block design. Diets were fed as a total mixed ration once daily. To reduce dietary CP, we replaced soybean meal with soybean hulls in the concentrate mix (DM basis). Diet evaluations suggested that several EAA, especially His, limited productivity as dietary CP declined. Digestibility of DM and CP decreased linearly with dietary CP reduction. Digestibility of neutral detergent fiber and potentially digestible neutral detergent fiber tended to respond in a quadratic pattern with the greatest digestibility at intermediate treatments. The reduction in dietary CP did not affect ruminal pH, but ruminal ammonia-N and branched-chain VFA concentrations declined linearly. The concentration of milk urea-N and plasma urea-N, secretion of milk N, and excretions of fecal N, urinary N, urinary urea-N, and unaccounted N decreased linearly with the reduction in dietary CP concentration. Urinary N expressed as a percentage of N intake was unaffected by dietary CP. Serum concentrations of total essential AA and non-essential AA were unaffected by dietary CP concentration. However, the ratio of essential to non-essential AA decreased with decreasing dietary CP. Serum 3-methylhistidine concentration increased linearly with decreasing dietary CP concentration, indicating greater skeletal muscle breakdown. Although our trial confirmed that reducing dietary CP decreased absolute excretion of urinary N, diet evaluations suggested that milk protein production decreased as certain essential AA became increasingly limited. Thus, reduced-CP diets have the potential to lessen reactive-N outputs of late lactation cows, but more research is needed to design diets that minimize deleterious effects on productivity.

138 Effects of Antibiotics and Low Crude Protein Diets on Growth Performance, Carcass Characteristics, and Disease Incidence of Growing Pigs

Abstract This study investigated the effect of antibiotics and low crude protein (CP) diets on growth performance, carcass characteristics, and disease incidence of growing pigs. Barrows (n = 180; 59-d-old; 18.5 ± 2.5 kg BW; AGPIC 800 × TN70) were distributed in a randomized complete block design, in a 2 × 2 factorial arrangement, nine replicates, and five pigs per pen. The factors were CP (18.5% or 13.0%) and antibiotics (none or 100 mg/kg tiamulin + 506 mg/kg oxytetracycline). Medicated diets were fed for 14 days. After that, all pigs were fed their respective CP diets for an additional 14 days (Post-medication period). Diets were formulated according to the NRC, (2012). Growth performance, backfat thickness, loin muscle area (ultrasound; Aloka SSD 500V), and disease incidence (couch and diarrhea) were evaluated. Data were analyzed using the Mixed procedure in SAS 9.4. For the first 14 days, pigs with antibiotics had improved (P &amp;lt; 0.05) BW, ADG, ADFI, and G:F compared with those without antibiotics. Pigs with 18.5% CP had greater (P &amp;lt; 0.05) BW, ADG, and G:F, whereas decreased (P &amp;lt; 0.05) ADFI compared with those with 13.0% CP. There was no interaction (P &amp;gt; 0.05) between CP and antibiotics for growth performance and carcass variables. Reduced (P &amp;lt; 0.05) cough and diarrhea incidence were observed in pigs fed antibiotics diets compared with those without antibiotics. Pigs fed 13.0% CP diets presented with less (P &amp;lt; 0.05) diarrhea incidence only when fed without antibiotics. During post-medication period, there was no carryover effect (P &amp;gt; 0.05) of antibiotics on growth performance, whereas pigs fed the 18.5% CP diets had greater (P &amp;lt; 0.05) BW, ADG, and G:F than those with 13.0% CP. Overall, G:F was improved (P &amp;lt; 0.05) by the use of antibiotics and the 18.5% CP diets improved (P &amp;lt; 0.05) ADG and G:F compared with 13.0% CP. Antibiotics did not have carryover effects (P &amp;gt; 0.05) on cough and diarrhea incidence whereas, pigs with 13.0% CP diets had less (P &amp;lt; 0.05) diarrhea incidence than those with 18.5% CP. Pigs fed 18.5% CP diets had improved (P &amp;lt; 0.05) loin muscle area compared with the 13% CP, whereas treatments did not influence the backfat thickness (P &amp;gt; 0.05). In conclusion, the reduction of dietary CP from 18.5% to 13.0% reduces the growth performance and loin muscle area of growing pigs, although it was effective to reduced diarrhea incidence. Antibiotics improved growth performance and reduced cough and diarrhea incidence. However, overall, only G:F was improved by the use of antibiotics.

The influence of dietary crude protein concentrations, grain types and arginine:lysine ratios on the performance of broiler chickens.

The objective of this study was to investigate the effects of dietary crude protein (CP) concentrations, grain types and arginine:lysine ratios on performance parameters of broiler chickens. The 2×2×2 factorial array of dietary treatments harnessed two CP concentrations (210 and 170g/kg), two feed grains (wheat and sorghum), and two arginine:lysine ratios (104 and 110). Each dietary treatment was offered to 7 replicates of 14 birds per floor pen, a total of 784 off-sex male, Ross 308 broilers, from 14 to 35d post-hatch. The dietary CP reduction compromised weight gain by 10.0% (2078 versus 2310g/bird) as a main effect and FCR by 7.51% (1.474 versus 1.371), subject to an interaction. In a three-way interaction (P=0.008), expanded arginine:lysine ratios improved FCR by 2.30% in 170g/kg CP, sorghum-based diets but compromised FCR by 2.12% in corresponding wheat-based diets. Sorghum was the more suitable feed grain in reduced-CP diets as sorghum generated significant advantages in weight gain of 7.59% (2154 versus 2002g/kg) and FCR of 6.94% (1.421 versus 1.527) in birds offered 170g/kg CP diets. Both dietary CP and feed grain generated significant and divergent impacts in apparent ileal digestibility coefficients for the majority of 16 assessed amino acids. Dietary CP reductions increased non-bound amino acid inclusions (NBAA) in wheat-based diets (48.96 versus 9.80g/kg) to a greater extent than sorghum-based diets (35.3 versus 9.50g/kg) and increasing dietary NBAA inclusions were linearly associated with compromised weight gain (r=-0.834; P<0.001) and FCR (r=0.862; P<0.001). Increasing ratios of free arginine to lysine plasma concentrations were linearly (r=-0.466; P=0.004) related to improvements in FCR. The implications of the observed outcomes are discussed and possible explanations are advanced.

Effect of Rumen-Protected Methionine on Metabolic Profile of Liver, Muscle and Blood Serum Samples of Growing German Simmental Bulls Fed Protein-Reduced Diets.

This study aimed to determine the metabolic response of growing German Simmental bulls fed rations low in crude protein (CP) supplemented with rumen-protected methionine (RPMET). In total, 69 bulls (on average 238 ± 11 days of age at start and 367 ± 25 kg of bodyweight) were assigned to three dietary treatments (n = 23/group): Positive control (CON; 13.7% CP; 2.11 g methionine/kg DM), negative control deficient in CP (RED; 9.04% CP; 1.56 g methionine/kg DM) and crude protein-deficient ration supplemented with RPMET (RED+RPMET; 9.04% CP; 2.54 g methionine/kg DM). At slaughter, samples of liver, muscle and blood serum were taken and underwent subsequent metabolomics profiling using a UHPLC-QTOF-MS system. A total of 6540 features could be detected. Twenty metabolites in the liver, five metabolites in muscle and thirty metabolites in blood serum were affected (p < 0.05) due to dietary treatments. In total, six metabolites could be reliably annotated and were thus subjected to subsequent univariate analysis. Reduction in dietary CP had minimal effect on metabolite abundance in target tissues of both RED and RED+RPMET bulls as compared to CON bulls. The addition of RPMET altered the hepatic anti-oxidant status in RED+RPMET bulls compared to both RED and CON bulls. Results exemplify nutrient partitioning in growing German Simmental bulls: bulls set maintenance as the prevailing metabolic priority (homeostasis) and nutrient trafficking as the second priority, which was directed toward special metabolic functions, such as anti-oxidant pathways.

Multiple amino acid supplementations to reduce dietary protein for pigs during early and late finisher periods under commercial conditions.

With the easy availability and competitive prices of crystalline amino acids (AAs), the reduction of dietary crude protein (CP) for pigs during early and late finisher periods is possible under commercial conditions. Two experiments were conducted to assess the growth efficiency of early and late-finishing pigs fed with protein-restricted diets supplemented with Lys, Met, Thr, Trp, Val, Ile and His. In Experiment 1, 840 early finishing pigs were allocated to four dietary treatments with CP levels designed at 150, 142, 134, and 126 g kg-1 diet. In Experiment 2, 768 late-finishing pigs were allotted to four dietary treatments providing CP levels at 140, 130, 120, and 110 g kg-1 diet. In Experiment 1, the data showed that CP levels could be decreased from 150 to 126 g kg-1 without adversely affecting performance of early finishing pigs as no significant difference was observed for final bodyweight, average daily gain (ADG), feed to gain ratio (F:G), or average daily feed intake (ADFI). In Experiment 2, late-finishing pigs consuming 120 g kg-1 CP tended to have the highest ADG and lowest F:G whereas those fed the 110 g kg-1 CP diet showed the opposite trend. Based on quadratic analysis, the optimum CP levels to maximize ADG and minimize F:G were 126 and 127 g kg-1 , respectively. These findings showed that dietary CP levels could be decreased to 126 g kg-1 for early finishing pigs while improved performance was noted in late-finishing pigs consuming 120 g kg-1 CP. © 2023 Society of Chemical Industry.

Reducing dietary crude protein in broiler diets positively affects litter quality without compromising growth performance whereas a reduction in dietary electrolyte balance further improves litter quality but worsens feed efficiency

Reducing crude protein (CP) in broiler feed is a nutritional strategy that allows to partially reduce dietary soybean meal (SBM) inclusions to reduce feed costs, with proven benefits. In addition, reduction of dietary CP leads to a lower dietary electrolyte balance (dEB) due to the concomitant reduction of potassium (K). The aim of the present study is therefore two-fold: 1) to evaluate the potential of reduction of dietary CP until performance drops (1, 2 or 3 % points of reduction) and 2) to combine it with a reduction of dEB (by reducing dietary K) to validate the benefit of reduced dEB/K on litter quality without compromising performance. In total, 9100 male Ross 308 chicks were randomly allotted to 35 pens of 260 broilers. They were fed 5 dietary treatments from 10 to 20d and 20–30d.There was a “positive control” diet (CONTROL; 20.7 % CP in grower, 19.5 % CP in finisher) and 3 levels of dietary CP reduction by 1 % (CP-1 %), 2% (CP-2 %) and 3 % (CP-3 %), all diets formulated to respect at least the ideal AA profile for indispensable AA. In addition, an extra diet called “negative control” (NC CP-3 %) was formulated to have the same ingredient composition as the CP-3 % diet but with lower K and dEB level. Reducing dietary CP as low as 3 % points and maintaining AA and dEB levels resulted in similar or better production performance from 10 to 30d for weight gain, feed intake, feed conversion ratio (FCR) and carcass traits, reduced daily water intake and water-to-feed ratio, excreta N and moisture as well as lower litter moisture and footpad lesions (FPL). Reducing dEB level at − 3 % CP (negative control) increased feed intake and FCR but reduced water intake, water-to-feed ratio, and FPL. It is therefore possible to feed broilers with lower CP diets without compromising performance, with clear benefit on litter quality. As reducing dietary CP is often associated to reduced dietary K, due to lower SBM inclusion, the extent of reduction of K and the control of dEB by Na, Cl and K need to be further explored, especially on litter quality, to facilitate the adoption of low protein diets in practice.

Effect of antibiotics and low-crude protein diets on growth performance, health, immune response, and fecal microbiota of growing pigs.

This study aimed to investigate the effects of diets with and without antibiotics supplementation and diets with 18.5% and 13.0% crude protein (CP) on growth performance, carcass characteristics, disease incidence, fecal microbiota, immune response, and antioxidant capacity of growing pigs. One hundred and eighty pigs (59-day-old; 18.5 ± 2.5 kg) were distributed in a randomized complete block design in a 2 × 2 factorial arrangement, nine replicates, and five pigs per pen. The factors were CP (18.5% or 13.0%) and antibiotics (none or 100 mg/kg tiamulin + 506 mg/kg oxytetracycline). Medicated diets were fed from days 59 to 73. After that, all pigs were fed their respective CP diets from 73 to 87 days. Data were analyzed using the Mixed procedure in SAS version 9.4. From days 59 to 73, pigs fed antibiotics diets had higher (P < 0.05) average daily feed intake (ADFI), average daily weight gain (ADG), gain to feed ratio (G:F), compared to the diets without antibiotics. From days 73 to 87 (postmedicated period), any previous supplementation of antibiotics did not affect pig growth performance. Overall (days 59 to 87), pigs-fed antibiotics diets had higher (P < 0.05) G:F compared to pigs-fed diets without antibiotics. In all periods evaluated, pigs fed 18.5% CP diets had higher (P < 0.05) ADG and G:F compared to pigs fed 13.0% CP. Pigs fed the 13.0% CP diets had lower (P < 0.05) fecal score and diarrhea incidence than those fed 18.5% CP. Pigs fed 18.5% CP diets had improved (P < 0.05) loin area compared to pigs-fed diets with 13.0% CP. At 66 days of age, pigs-fed antibiotics diets had lower (P < 0.05) alpha diversity estimated with Shannon and Simpson compared to the pig-fed diets without antibiotics. At family level, pigs fed 18.5% CP diets had higher (P < 0.05) relative abundance of Streptococcaceae, and lower (P < 0.05) relative abundance of Clostridiaceae at days 66 and 87 compared with pigs fed 13.0% CP. Pigs-fed antibiotics diets had lower (P < 0.05) immunoglobulin G and protein carbonyl concentrations at day 66 compared to the pigs-fed diets without antibiotics. The reduction of dietary CP from 18.5% to 13.0% reduced the growth performance and loin muscle area of growing pigs, although it was effective to reduce diarrhea incidence. Antibiotics improved growth performance, lowered diarrhea incidence, improved components of the humoral immune response, and reduced microbiota diversity. However, in the postmedicated period, we found no residual effect on the general health of the animals, and considering the overall period, only G:F was improved by the use of antibiotics.

242 The Impact of Feed Formulation and Feeding Methods on Pig and Poultry Production on the Environment

Abstract Dietary energy and nutrient losses associated with its conversion into animal products increase production costs and contribute to the environmental footprint of farms with the excessive application of nitrogen, phosphorus, or trace minerals from manure or carbon and methane losses. Formulating diets with the appropriate levels of minerals and amino acids can help improve dietary protein and energy efficiency and reduce nutrient losses. For example, an 8% reduction in dietary crude protein in pig feeds is estimated to increase nitrogen efficiency by more than 50%, while costing 11% less than a control diet without industrial amino acids. This reduction in protein intake also increases energy availability due to reduced energy losses associated with protein deamination. Urinary and intestinal fermentation energy losses can be 24% lower for pigs fed low-protein diets compared to control diets. Nonetheless, determining the optimal level of dietary amino acid remains a difficult challenge in conventional phase feeding systems. Therefore, group or individual precision feeding is another powerful tool to increase nutrient efficiency. By feeding individual growing-finishing pigs with diets tailored to their requirements, precision feeding can decrease nitrogen excretion by 30% and greenhouse gas emissions by 22% compared to conventional 3-phase feeding. The benefits of feeding pigs with low-protein diets and precision feeding techniques are additive and might result in a 61% protein efficiency of utilization. The formulation of very-low-protein diets and the implementation of precision feeding techniques rely on sound nutritional concepts and comprehensive biological models developed to precisely estimate individual real-time nutrient requirements and animal responses. Understanding the metabolic processes responsible for the observed variation between individual animals in their ability to utilize dietary nutrients is challenging, but there is a need to further improve nutrient efficiency and reduce the environmental impact of livestock production systems.

Elevated branched-chain amino acid inclusions generate distinctly divergent growth performance responses in broiler chickens offered wheat- and/or sorghum-based, reduced-crude protein diets

The objective of this study was to determine the effects of elevated branched-chain amino acid (BCAA) inclusions in 187.5 g/kg crude protein (CP) diets based on wheat, sorghum or a wheat-sorghum blend on performance parameters of broiler chickens from 7 to 28 days post-hatch. The first tier of BCAA inclusions relative to lysine were leucine 105, isoleucine 65 and valine 75. The second tier was an elevation of leucine to 150 individually and in the third tier leucine was maintained at 150 and isoleucine and valine were elevated to 75 and 85, respectively. A 3 × 3 factorial array of these dietary treatments were offered to a total of 324 male Ross 308 broiler chickens housed in six replicate cages per treatment with six birds per cage. The assessed performance parameters included growth performance, relative abdominal fat-pad weights, nutrient utilisation, apparent jejunal and ileal digestibility coefficients of starch, protein (N) and amino acids and free amino acid concentrations in systemic plasma. Treatment interactions were observed for weight gain (P < 0.001) and FCR (P < 0.014). Elevated BCAA inclusions in sorghum-based diets significantly increased weight gain by 9.26 % (1451 versus 1328 g/bird) and numerically improved FCR by 0.86 % (1.378 versus 1.390). In contrast, elevated BCAA inclusions in wheat-based diets significantly depressed both weight gain by 9.49 % (1288 versus 1423 g/bird) and FCR by 8.33 % (1.665 versus 1.537). Wheat-based diets (5.68 g/kg) generated significantly lighter relative abdominal fat-pad weights than either sorghum-based (13.48 g/kg) or blended diets (12.95 g/kg). Sorghum-based and blended diets supported superior energy utilisation and N retention in comparison to wheat-based diets. Similarly, sorghum-based and blended diets supported higher jejunal and ileal starch digestibility coefficients than wheat-based diets, but wheat supported significantly higher jejunal protein (N) digestibility by 10.5 % (0.726 versus 0.657). Treatment interactions were observed for ileal digestibility of 4 amino acids (arg, lys, val, gly), BCAA inclusions significantly influenced 3 amino acids (ile, leu, thr) and the feed grain significantly influenced 10 amino acids (his, ile, leu, met, phe, ala, asp, glu, pro, tyr). Elevating BCAA inclusions in wheat-sorghum blended diets significantly increased free plasma concentrations of leucine and influenced concentrations of isoleucine and valine. However, BCAA inclusions significantly decreased plasma concentrations of threonine, asparagine plus aspartic acid, cysteine, glycine, proline, and serine. Consideration is given to possible reasons for the remarkable weight gain treatment interaction following elevated BCAA inclusions to sorghum- or wheat-based diets.

Capping dietary starch: Protein ratios enhances performance of broiler chickens offered reduced-crude protein, maize-based diets

The objective of this study was to determine if capping dietary starch:protein ratios in reduced-crude protein diets enhances growth performance of broiler chickens offered maize-based diets. A total of 288 off-sex, male Ross 308 chickens were offered a 2 × 3 factorial array of dietary treatments from 7 to 35 days post-hatch. Dietary starch:protein ratios were either standard (mean: 2.47) or capped (mean: 2.12) with three dietary crude protein concentrations of 195, 185 and 175 g/kg. Dietary starch:protein ratios were capped by substituting soybean meal with full-fat soy; sourced from the same supplier. The parameters assessed included growth performance, relative abdominal fat-pad weights, nutrient utilisation, excreta nitrogen concentrations, distal jejunal and distal ileal digestibility coefficients and disappearance rates of starch and protein, jejunal and ileal starch:protein disappearance rate ratios, distal jejunal and distal ileal apparent amino acid digestibility coefficients, distal ileal amino acid disappearance rates and free amino acid concentrations in systemic plasma. Capping dietary starch:protein ratios significantly reduced ileal starch:protein disappearance rate ratios in birds offered 195, 185 and 175 g/kg crude protein by 14.6% (2.40–2.05), 13.8% (2.61–2.25) and 29.3% (3.75–2.65), respectively. Capping starch:protein ratios in 175 g/kg crude protein diets significantly improved weight gain by 3.45% (2398 versus 2318 g/bird) and feed conversion ratio by 3.75% (1.360 versus 1.413) and relative abdominal fat-pad weights were numerically lighter by 10.3% (11.47 versus 12.78 g/kg). Condensing ileal starch:protein disappearance rate ratios were quadratically related (P < 0.001) to improvements in weight gain (r = 0.740), feed conversion ratio (r = 0.786) and lighter fat-pad weights (r = 0.650). Reducing dietary crude protein concentrations depressed apparent ileal digestibility coefficients of 15 of the 16 amino acids assessed (P = 0.021 to < 0.001); average coefficients were reduced by 6.74% (0.803 versus 0.861). These compromised amino acid digestibilities probably contributed to the 6.43% inferior weight gains (2358 versus 2520 g/bird; P < 0.001) and 3.05% inferior feed conversion ratio (1.387 versus 1.346; P < 0.001) following the dietary crude protein reduction from 195 to 175 g/kg. A better comprehension of the impacts of reduced crude protein diets on endogenous amino acid flows and accumulations of microbial amino acids in distal ileal digesta needs to be achieved as both factors will influence apparent amino acid digestibility coefficients. Finally, capping dietary starch:protein ratios in 175 g/kg crude protein diets showed distinct promise in this study as both weight gain and FCR were significantly enhanced.

167 Effect of Reducing Dietary Crude Protein on Growth Performance of Fattening Pigs: A Meta-Analysis

Abstract Reducing dietary crude protein (CP) is a nutritional strategy implemented to improve the sustainability of pig production. Its effect on growth performance has been broadly studied in fattening pigs but the literature is lacking a quantitative summary of the knowledge acquired. A meta-analysis was performed to assess the effects of reducing dietary CP on pig growth performance. Articles included in the meta-analysis studied effects of CP reduction, with at least 3 CP levels, on the growth performance of fattening pigs (20-115 kg) and were published from 1990 to 2019. The database contained 42 articles, which correspond to 67 trials. Diet composition was recalculated with INRA-AFZ (2004) tables. Trials using iso-digestible lysine and iso-net energy diets with constant or above requirements levels of essential amino acids (EAA, METEX NØØVISTAGO recommendations) were selected for the final analysis, with a 5% acceptance limit. The final selection contained 11 trials and 44 treatments. The general linear model procedure of MINITAB (2019) was used to build regression models, including a fixed trial effect. Dietary CP reduction tested ranged between 1.6 and 7.5 percentage points (%pt) and was performed by reducing soybean meal and increasing cereals inclusion in all trials except one using rapeseed meal. Reducing dietary CP did not significantly impacted feed intake, average daily gain or feed conversion ratio when EAA were adequately supplied. Nitrogen efficiency was improved by 2.7 %pt per %pt of CP reduction (P &amp;lt; 0.001). No statistical analysis could be performed on carcass composition data as there were only 6 trials remaining after selection for these parameters, but fatter carcasses were observed in half of the trials. This study highlighted that few CP reduction studies have been performed while controlling energy and EAA levels. There was no effect of reducing dietary CP on growth performance when those parameters were controlled but more research is needed on very low CP diets for fattening pigs.