Low Crude Protein Diets Research Articles

Impact of low crude protein diets containing animal byproducts on growth performance, nitrogen excretion, meat yield and quality in broiler chickens

This study examined the impact of a low crude protein (CP) diet incorporating meat and bone meal (MBM) as an alternative (AD) to standard diet, on broiler performance, nitrogen intake, excretion, and meat quality. A total of 846 male Ross 308 chicks were assigned to two diets in a randomized complete block design with 9 replicates of 47 birds/replicate. The diets were a plant-based control (20.4 and 19.5% CP) and an AD diet (-2.0% CP, +2.5% MBM) in the grower and finisher phases. Compared to the control, the AD diet reduced nitrogen intake (P = 0.01) and excretion (P < 0.01) while improving nitrogen retention efficiency (P < 0.001) without affecting body weight, feed conversion, or carcass yield. Breast yield was higher in the AD group (P < 0.001). In the AD group, the ultimate pH of breast meat increased slightly (P = 0.07), cooking loss decreased (P = 0.002), sarcoplasmic protein solubility tended to increase (P = 0.09), while muscle protein emulsifying properties remained unchanged. Breast meat proximate composition was not affected by the AD diet. In conclusion, the AD diet can reduce nitrogen loss and emissions without negatively impacting broiler production, provided that amino acid requirements are met.

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.

Environmental benefits of crude protein reduction in growing pig diets: is it worth going further?

Nitrogen (N) excretion and emissions can be reduced in fattening pigs by reducing dietary crude protein (CP) levels. Effects of this strategy are well documented for moderate CP reduction, but little literature exists on further CP reduction made possible by free isoleucine, histidine, and leucine. This trial evaluated the effects of 2 levels of reduction in CP on growth performance, N balance, and gaseous emissions. Forty-eight pigs were allocated to 12 gaseous emission-measuring chambers at 28kg live weight. Three dietary treatments (CTRL; -1.2pt; -2.4pt), with a CP content, respectively, of 18.1%, 16.9%, and 15.0% in phase 1 (28 to 48kg) and 16.1%, 15.0%, and 13.8% in phase 2 (48 to 80kg), were fed ad libitum. Growth performance was recorded for each phase. Body lipid and protein composition were analyzed by dual-energy X-ray absorptiometry in 2 animals per chamber at the beginning and end of the trial. These results were used to calculate the N balance. Slurry volume and composition were measured at the end of the trial. Ammonia, methane, and nitrous oxide emissions were recorded continuously. Data were analyzed with a general linear model including the linear and quadratic effect of CP reduction and phase as fixed effects. A trend for a quadratic effect of CP reduction on feed intake was observed (P = 0.085) with a decrease from CTRL to -1.2pt and then an increase with the -2.4pt treatment. Daily gain and gain to feed were improved by the low CP diets in phase 1 but were degraded in phase 2 (phase × CP interaction, P < 0.001) while body composition was not affected. Nitrogen excretion decreased with CP reduction (linear effect, P = 0.023) but tended to plateau with the low CP diets (quadratic effect, P = 0.081). Methane emissions per kg of gain were reduced with CP reduction (linear effect, P = 0.031). Ammonia emissions decreased with CP reduction, mostly in phase 1 (phase × CP interaction, P = 0.015); however, the emission factor (g N-NH3 / g urinary N) was not affected. Nitrous oxide emissions were not affected by CP reduction and its emission factor (g N-N2O / g N) tended to increase (linear effect, P = 0.07). Slurry ammonia-N decreased (linear effect, P < 0.023; quadratic effect, P = 0.049), but other slurry components were not significantly impacted. In this trial, a plateau in N excretion and emission reduction was reached with the -2.4pt treatment. Nevertheless, it is important to study such a reduction in conditions closer to commercial ones.

PSII-20 Effect of increasing glycine equivalent in low crude protein diets on growth performance in broiler chickens raised under multiple stress conditions

Abstract The objective of the current experiment was to investigate the effects of increasing glycine (Gly) equivalent in low crude protein (LCP) diets on growth performance in broiler chickens raised under multiple stress (MS) conditions. Ross 308 broiler chickens (n = 450; 22 d of age) were randomly allotted to 1 of 6 treatments with 6 replicates in a 2 × 3 factorial arrangement. The first factor included two different environmental conditions (normal condition vs. MS condition) and the second factor included three dietary treatments (CON, control diets; LCP, low crude protein diets; LCP+Gly, LCP diets with Gly supplementation). Birds in normal conditions were raised under recommended environmental conditions (22 ± 0.9°C and 53.6 ± 5.99 %) with low stock density (SD; 16.9 birds/m2). Birds in MS conditions were exposed to a cyclic heat stress condition (32 ± 0.1°C for 8 h/d and 26°C ± 0.3°C for the remaining time) with high SD (25.3 birds/m2). The average relative humidity was 37.9 ± 4.94%. In addition, 15 birds per cage were assigned in MS conditions to increase SD, whereas 10 birds per cage were assigned in normal conditions. The treatment diets included CON diets with adequate energy, crude protein (19.50% CP and 1.15% Gly equivalents), and other nutrients recommended for growing broiler chickens and LCP diets with low CP content (16.50% CP and 1.15% Gly equivalents) but adequate other nutrients. The LCP+Gly diets had increasing concentrations of Gly equivalents (17.19% CP and 1.73% Gly equivalents) by Gly supplementation to LCP diets. The diets and water were provided ad libitum throughout the experiment. Experiment lasted for 16 d from 22 d to 37 d of age. At the conclusion of the study, growth performance including body weight gain (BWG), feed intake (FI), and feed conversion ratio (FCR) was determined. All data were analyzed by 2-way ANOVA in a completely randomized design using the PROC MIXED procedure of SAS (SAS Institute Inc., Cary, NC). Results indicated that no interactions between environmental conditions and dietary treatments were observed for all growth performance measurements (Table 1). For the main effects, as expected, MS conditions decreased (P &amp;lt; 0.001) growth performance of broiler chickens, regardless of dietary treatments. The LCP diets increased (P &amp;lt; 0.05) FI and FCR as compared with CON diets, regardless of environmental conditions. However, LCP+Gly diets decreased FI (P &amp;lt; 0.05) and tended to decrease FCR (P = 0.076) as compared with LCP diets. In conclusion, either MS conditions or LCP diets impair growth performance in broiler chickens with no significant interaction. However, increasing Gly equivalents by Gly supplementation to LCP diets are likely to improve feed efficiency in broiler chickens regardless of stress environments.

469 Reducing crude protein levels with amino acid supplementation in the finishing diets of heavy Duroc sire line pigs: Effects on carcass and meat traits in males and females

Abstract Nutrition represents 70% of pig production costs, particularly protein; therefore, decreasing protein costs is of capital importance. Reducing crude protein (CP) contents to levels below recommended whilst supplementing with amino acids (AAs) is an interesting strategy to reduce costs without decreasing production performances. It has been conducted essentially in lean genotypes during the growth stage. Few studies address heavy genotypes or sex differences during the finishing period. Our objective is to study carcass and meat (loin) traits of heavy [Duroc X (Landrace X Large-White)] male and female pigs during the finishing stage under a 2% CP reduction with crystalline AA supplementation, hypothesizing that both sexes will be affected equally. In total, 60 males and 60 females, 9 wk old animals were used and allotted in split-sex pens (6 pigs/pen) with water and dry feed ad libitum. At 15 wk of age, when pigs weighed an average of 68 kg, two isoenergetic diets with different CP levels were provided (145 and 125 g CP/kg, control and low-CP) during the last 42 d of fattening. In the low-CP diet, crystalline AAs were added. On last day of the trial, animals weighed 116.5 kg on average and were slaughtered. Hot carcass weights and yields, ham fat thickness, lean meat percentage and boar taint by human nose scoring were determined. Loin samples (one per pen) were used to determine thawing losses, pH, color, Texture Profile Analysis (TPA: hardness, cohesiveness, springiness) and chemical composition (moisture, ash, protein, collagen, fat, and saturated fat). Data were analyzed using the simple least squares models that included dietary treatment and sex and their interaction as fixed effects with the pen as the experimental unit. Carcass weights were greater in control males than in females (91.2 vs 85.7 kg; P &amp;lt; 0.05). No effect of sex or diet was detected on carcass yields, lean contents or ham subcutaneous fat thickness. There was a great impact of sex for loin subcutaneous fat thickness, with males having 7 to 8% greater values in both dietary treatments (P = 0.011). Low-CP females had a greater percentage of carcasses of greater lean content compared with the three other groups (P &amp;lt; 0.05). Boar taint, carcass pH, color traits, chemical analysis and TPA did not differ across diets. A strong dietary influence was noticeable with animals of both sexes in the Low-CP diets having greater fat and saturated fat contents than animals in the control groups (P = 0.02). In conclusion, the 20g/kg CP reduction supplemented with AAs can efficiently be used in heavy Duroc sire line genotype during the finishing phase without leading to major impairments in carcass or meat traits, regardless of sex.

470 Reducing crude protein levels with amino acid supplementation in the finishing diets of heavy Duroc sire line pigs: Effects on growth performance and nitrogen balance in males and females

Abstract Nutrition represents 70% of pig production costs, particularly protein; then, decreasing protein costs is of capital importance. Reducing crude protein (CP) contents to levels below recommended whilst supplementing with amino acids (AAs) is an interesting strategy to reduce costs without decreasing production performances with environmental benefits. It has been conducted essentially in lean genotypes during the growth stage. Few studies address heavy genotypes or differences between males and females during the finishing period. Our objective is to study productive performances of heavy [Duroc X (Landrace X Large-White)] male and female pigs during the finishing stage under a 2% CP reduction with crystalline AA supplementation, hypothesizing that both sexes will equally be affected. In total, 60 males and 60 females were used. At 9 wk of age, animals were allotted in split-sex pens (6 pigs/pen, 0.9 m2/animal) with water and dry feed ad libitum. At 15 wk of age, when pigs weighed an average of 68 kg, two isoenergetic diets with different CP levels were provided (145 and 125 g CP/kg, control and low-CP) during the last 42 d of fattening, under the ideal protein concept. In the low-CP diet, crystalline AAs were added. Feed intake was measured daily, and animals were weighed every 3 wk to calculate average daily feed intake (ADFI), average daily gain (ADG), feed conversion ratio (FCR) and N balance on d 21 and 42. Data were analyzed using the simple least squares models that included dietary treatment and sex and their interaction as fixed effects with the pen as the experimental unit. At d 21, animals weighed 90 to 95 kg with males being 5 to 6 % heavier (P &amp;lt; 0.01). No significant differences were recorded regarding diet. The same difference (P &amp;lt; 0.001) was recorded at day 42, with males (119-122 kg) being 7.25% heavier than females in both treatments. Males had 16% higher ADGs than females in both treatments (P &amp;lt; 0.0001) No differences were recorded for ADFI as a consequence of sex for both diets. FCRs were higher in females of both nutritional treatments (P &amp;lt; 0.0001). Retained N was 22% greater in males than in females for both dietary treatments. The N efficiency was greater in Low CP males by comparison with low CP females and control males, whereas control CP females had decreased N efficiency compared with all other experimental groups. Results demonstrate that the 20g/kg CP reduction supplemented with AAs can efficiently be used in heavy Duroc sire line genotypes during the finishing phase without a decrease in production parameters with females having poorer growth performances than males, whereas N efficiency was impaired when females had no limiting dietary CP.

Different dietary branched-chain amino acid ratios, crude protein levels, and protein sources can affect the growth performance and meat yield in broilers

Balanced ratios of branched-chain amino acids (BCAAs) can enhance chicken growth, immunity, and muscle synthesis. However, these ratios can be affected by changes in crude protein (CP) levels or the substitution of protein sources, leading to BCAA antagonism. This, in turn, can have a negative impact on chicken growth. In Experiment 1, a total of 960 0-d-old male Cobb 500 broilers were divided into 6 treatments with 8 replicates. Three different BCAA ratios were used in High or Low CP diets as follows: 1) Low Leu group (Low level of leucine with increased valine and isoleucine levels), 2) Med Leu group, and 3) High Leu group (High level of leucine with reduced valine and isoleucine levels) for a total of 6 diets. In Experiment 2, a total of 640 0-d-old male Cobb 500 broilers were divided into 4 treatments with 8 replicates. The four diets had either High or Low CP and one of two protein sources with the same medium levels of BCAAs: 1) the soybean meal (SBM) group, which had SBM as the main protein source (protein bound AA), and 2) the wheat middlings with non-bound AAs (WM+AA) group (non-bound AA), which had additional non-bound AAs to replace SBM. The High Leu diet had a negative effect on overall growth performance, carcass weight, breast muscle weight, and body mineral composition compared to the Low Leu and Med Leu groups, particularly in the High CP diet (P < 0.05). The SBM group showed increased growth performance, breast muscle weight, expression levels of genes promoting muscle growth, and improved bone mineral composition compared to the WM+AA group, and the High CP group intensified the negative effect of the WM+AA diet (P < 0.05). In summary, balanced BCAA ratios and SBM-based diets have positive effects on chicken growth and muscle accretion, whereas excessive leucine and non-bound AA levels in the diets may negatively affect growth performance and meat yield in chickens.

High-level L-Gln compromises intestinal amino acid utilization efficiency and inhibits protein synthesis by GCN2/eIF2α/ATF4 signaling pathway in piglets fed low-crude protein diets

Gln, one of the most abundant amino acids (AA) in the body, performs a diverse range of fundamental physiological functions. However, information about the role of dietary Gln on AA levels, transporters, protein synthesis, and underlying mechanisms in vivo is scarce. The present study aimed to explore the effects of low-crude protein diet inclusion with differential doses of L-Gln on intestinal AA levels, transporters, protein synthesis, and potential mechanisms in weaned piglets. A total of 128 healthy weaned piglets (Landrace × Yorkshire) were randomly allocated into four treatments with four replicates. Pigs in the four groups were fed a low-crude protein diet containing 0%, 1%, 2%, or 3% L-Gln for 28 d. L-Gln administration markedly (linear, P < 0.05) increased Ala, Arg, Asn, Asp, Glu, Gln, His, Ile, Lys, Met, Orn, Phe, Ser, Thr, Tyr, and Val levels and promoted trypsin activity in the jejunal content of piglets. Moreover, L-Gln treatment significantly enhanced concentrations of colonic Gln and Trp, and serum Thr (linear, P < 0.01), and quadratically increased serum Lys and Phe levels (P < 0.05), and decreased plasma Glu, Ile, and Leu levels (linear, P < 0.05). Further investigation revealed that L-Gln administration significantly upregulated Atp1a1, Slc1a5, Slc3a2, Slc6a14, Slc7a5, Slc7a7, and Slc38a1 relative expressions in the jejunum (linear, P < 0.05). Additionally, dietary supplementation with L-Gln enhanced protein abundance of general control nonderepressible 2 (GCN2, P = 0.010), phosphorylated eukaryotic initiation factor 2 subunit alpha (eIF2α, P < 0.001), and activating transcription factor 4 (ATF4) in the jejunum of piglets (P = 0.008). These results demonstrated for the first time that a low crude protein diet with high-level L-Gln inclusion exhibited side effects on piglets. Specifically, 2% and 3% L-Gln administration exceeded the intestinal utilization capacity and compromised the jejunal AA utilization efficiency, which is independent of digestive enzyme activities. A high level of L-Gln supplementation would inhibit protein synthesis by GCN2/eIF2α/ATF4 signaling in piglets fed low-protein diets, which, in turn, upregulates certain AA transporters to maintain AA homeostasis.

Impact of lowering nitrogen content in pig manure through low crude protein diets on anaerobic digestion process stability, biogas yields, and digestate composition

Lowering crude protein in pig diets can reduce nitrogen (N) excretion and alter manure characteristics. Anaerobic digestion (AD) offers potential for converting pig manure into biogas and bio-based fertilizers (i.e., digestate). However, limited research exists on the effects of N content in pig manure on AD when pigs are fed diets with varying crude protein levels. This study investigated how lowering N content in pig manure through low crude protein diets may affect AD process stability, biogas generation, and digestate properties. Manures from different dietary treatments, named as control (CON), low N (LN), and very low N (VLN), with Total Kjeldahl Nitrogen concentrations of 5.87, 5.42, and 5.15 g/L, respectively, were investigated. Daily biogas production, composition (CH4, CO2, and H2S), and digestate properties were monitored over 13 fed-batch cycles (25 ± 4 days per cycle). The experiment was conducted at 20 ± 1 °C, a condition suited for milder climate regions, using six single-stage digesters operated in sequencing fed-batch mode. Data were analyzed by ANOVA using PROC MIXED with repeated measures. Results showed that the differences in N content in pig manure due to the three dietary treatments had a limited impact on biogas generation, with specific methane yields remaining similar over time. CH4 concentrations remained stable between 60 and 65 %, ensuring high-quality biogas despite dietary variations. Differences between treatments became more pronounced with increased organic loading rates (OLRs) due to variations in the amount of volatile solids fed. AD also remained stable (Total Volatile Fatty Acids/Total Alkalinity <0.25) even at an OLR of 2.15 g of chemical oxygen demand L−1 day−1, highlighting AD's robustness at lower temperatures. Digestate samples contained essential minerals beneficial for plant growth. More research is needed to explore varied manure compositions and feeding strategies to better understand the interactions of animal nutrition with AD.

Addition of Spray-Dried Plasma in Phase 2 Diets for Weanling Pigs Improves Growth Performance, Reduces Diarrhea Incidence, and Decreases Mucosal Pro-Inflammatory Cytokines.

The hypothesis that pigs fed a low crude protein (CP) diet with 6% spray-dried plasma (SDP) in phase 1 will have improved growth and intestinal health if the phase-2 diet contains 2.5% SDP was tested. Three hundred weaned pigs were used. Growth performance, feces, blood, and intestinal tissue were evaluated. Pigs fed 6% SDP in phase 1 had improved average daily gain (ADG) and final body weight (BW), but had reduced villus-height-to-crypt-depth ratio in phase 2 if 2.5% SDP was included in the normal-CP diet (p < 0.05), but not in the low-CP diet. Diarrhea incidence was less (p < 0.05) with 2.5% SDP in the phase 2 diet and for the low-CP diet. Ileal mucosa interleukin-1α (IL-1α) and IL-1β decreased (p < 0.05) for pigs fed the phase-1 diet with 6% SDP compared with pigs fed the diet without SDP. Addition of 2.5% SDP in phase 2 reduced (p < 0.05) IL-1β compared with the diet without SDP. Although the combination of SDP and low CP did not affect intestinal health in phase 2, diarrhea incidence and pro-inflammatory cytokines were reduced in pigs fed SDP in phase 1 or phase 2 or if a low-CP diet was fed.

Dietary Crude Protein and Lysine Levels Affect Meat Quality and Myofiber Characteristic of Slow-Growing Chicken.

This study aimed to investigate the effects of dietary crude protein (CP) and lysine levels on growth performance, slaughter performance, meat quality, and myofiber characteristics of slow-growing chicken. A 3 × 3 factorial experiment was arranged, and the chickens were fed with 3 levels of dietary CP (16.0%, 17.0%, 18.0%) and 3 levels of dietary lysine (0.69%, 0.84%, 0.99%). A total of 540 8-week-old Beijing-You Chicken (BYC) female growing chickens were randomly allocated to 9 groups, 5 replicates per group, and 12 chickens per replicate. The birds were randomly allocated to one of the 9 experimental diets. Growth performance, slaughter performance, meat quality, and myofiber characteristics were determined at 16 weeks of age. The results showed that dietary CP level and the interaction of dietary CP and lysine levels affected average feed intake (AFI) (p < 0.05). The AFI in the 16.0% CP and 17.0% CP groups was higher than in the 18.0% CP group (p < 0.05). Dietary CP levels significantly affected body weight gain (BWG) (p < 0.05) at 9 to 16 weeks. The 18.0% CP group had the highest BWG (93.99 g). Dietary CP levels affected the percentage of leg muscle yield, and the percentage of leg muscle yield of the 16.0% CP group was significantly lower than that in the other two groups (p < 0.05). Dietary CP and lysine levels alone and their interactions did not affect pH24h, drip loss, and cooking loss of breast muscle (p > 0.05). The shear force of the 18.0% CP group (29.55 N) was higher than that in the other two groups (p < 0.01). Dietary CP level affected myofiber characteristic (p < 0.01), with the lowest myofiber density (846.35 p·mm-2) and the largest myofiber diameter (30.92 μm) at 18.0% CP level. Dietary lysine level affected myofiber diameter, endomysium thickness, perimysium thickness (p < 0.01), with the largest myofiber diameter (29.29 μm) obtained at 0.84% lysine level, the largest endomysium thickness (4.58 μm) at 0.69% lysine level, and the largest perimysium thickness (9.26 μm) at 0.99% lysine level. Myofiber density was negatively correlated with myofiber diameter and endomysium thickness (R = -0.883, R = -0.523, p < 0.01); perimysium thickness had a significant negative correlation with shear force (R = -0.682, p < 0.05). Therefore, reducing dietary CP level and adding appropriate lysine can reduce myofiber diameter and increase perimysium thickness, reducing shear force and improving meat tenderness. A high lysine level (0.99%) in the low-CP (16.0%) diet can improve meat tenderness by regulating the myofiber characteristic without affecting production performance.

Effects of improved amino acid balance diet on lysine mammary utilization, whole body protein turnover and muscle protein breakdown on lactating sows

BackgroundThe study objective was to test the hypothesis that low crude protein (CP) diet with crystalline amino acids (CAA) supplementation improves Lys utilization efficiency for milk production and reduces protein turnover and muscle protein breakdown. Eighteen lactating multiparous Yorkshire sows were allotted to 1 of 2 isocaloric diets (10.80 MJ/kg net energy): control (CON; 19.24% CP) and reduced CP with “optimal” AA profile (OPT; 14.00% CP). Sow body weight and backfat were recorded on d 1 and 21 of lactation and piglets were weighed on d 1, 14, 18, and 21 of lactation. Between d 14 and 18, a subset of 9 sows (CON = 4, OPT = 5) was infused with a mixed solution of 3-[methyl-2H3]histidine (bolus injection) and [13C]bicarbonate (priming dose) first, then a constant 2-h [13C]bicarbonate infusion followed by a 6-h primed constant [1-13C]lysine infusion. Serial blood and milk sampling were performed to determine plasma and milk Lys enrichment, Lys oxidation rate, whole body protein turnover, and muscle protein breakdown.ResultsOver the 21-d lactation period, compared to CON, sows fed OPT had greater litter growth rate (P < 0.05). Compared to CON, sows fed OPT had greater efficiency of Lys (P < 0.05), Lys mammary flux (P < 0.01) and whole-body protein turnover efficiency (P < 0.05). Compared to CON, sows fed OPT tended to have lower whole body protein breakdown rate (P = 0.069). Muscle protein breakdown rate did not differ between OPT and CON (P = 0.197).ConclusionFeeding an improved AA balance diet increased efficiency of Lys and reduced whole-body protein turnover and protein breakdown. These results imply that the lower maternal N retention observed in lactating sows fed improved AA balance diets in previous studies may be a result of greater partitioning of AA towards milk rather than greater body protein breakdown.

142 Evaluation of low SID lysine diets fed to enteric health challenged pigs on wean-to-finish performance

Abstract Producers have been adopting low crude protein or low SID Lys nursery diets to address enteric health concerns. Therefore, we evaluated the longitudinal impact of these strategies on lifetime pig performance. Weaned mixed sex pigs n = 588; initial body weight (BW) = 6.81 ± 1.34 kg] sourced from a poor enteric health flow, were randomly assigned to pens and to one of four nursery dietary treatments, fed for 7 wk. Following the nursery period, pens were then assigned to one of two grow-finish treatments, fed until marketing, to complete a 2 × 2 × 2 factorial design (n = 6 pens/treatment, 12 to 13 pigs/pen). Phase 1 nursery diets were formulated to a 1.10% or 1.40% SID Lys (nLLys or nHLys) with amino acids (AA) provided by both soybean meal (SBM) and crystalline AA or SBM only (nLSBM or nHSBM, respectively). Nursery phase 2 and 3 diets were formulated with a 0.05% decrease in SID Lys while maintaining a 0.30% differential between high and low lysine treatments. Following the nursery, grow-finish pigs were fed diets formulated to equal SID Lys:ME with either a conventional crystalline AA (gfLSBM) or high SBM diet lacking crystalline AA (gfHSBM) to meet AA requirements. During the nursery, enteric health was assessed by fecal pathogen PCRs and bacterial culture, confirming a high natural rotavirus and F18 enterotoxigenic Escherichia coli burden. Pig BW and pen feed disappearance were recorded at the beginning and end of each phase to calculate average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (gain to feed ratio; G:F). Data were analyzed with pen as the experimental unit and the fixed effects of nursery SID Lys (nLys), nursery SBM (nSBM), grow-finish SBM (gfSBM), and the two- and three-way interactions using ANOVA. There were no three-way interactions for ADG or ADFI on final performance and no two-way interactions of nLys by nSBM in the nursery. Additionally, there was no effect of nSBM on overall nursery ADG, ADFI, and G:F (P &amp;gt; 0.05). Pigs fed nHLys-gfHSBM (0.84 kg/d) had improved overall ADG versus pigs fed nLLys-gfHSBM (0.80 kg/d; interaction; P = 0.010). Final nursery ADG (0.47 vs. 0.42 kg/d), G:F (0.70 vs. 0.63), and ending BW (30.9 vs. 28.0 kg) were greater in pens fed nHLys compared with nLLys (P &amp;lt; 0.001). Grow-finish pigs fed gfHSBM were more efficient compared with gfLSBM overall (0.457 vs. 0.449, respectively; P = 0.016). Although pigs fed nHLys had improved ending ADG compared with nLLys (0.83 vs. 0.81 kg/d; P = 0.018, respectively), there were no differences in final BW (128.0 vs. 127.0 kg) or ADFI (1.83 vs. 1.80 kg/d; P &amp;gt; 0.05). In conclusion, low SID Lys enteric diets did not improve wean-to-market pig performance in enterically challenged pigs and there was no difference between amino acid sources (crystalline vs SBM).

PSVI-18 Low and high feed efficiency grower-finisher pigs fed three different levels of dietary crude protein showed no immediate difference in blood metabolomics profile

Abstract Improving feed efficiency (FE) of grower-finisher pigs is of great importance considering its impact on production economy, nutrient excretions as well as carbon-footprint. The biological background describing variation in FE between pen mates, is difficult to establish as feed intake (FI) and FE are not estimated on an individual level. In this study advanced feeding stations were used to estimate FI and further calculate feed conversion ratio (FCR) on individual level. The study aimed to investigate the possible difference in the blood metabolic profile between low and high FE grower-finisher pigs fed three different levels of dietary crude protein (CP). The study included 60 newly weaned gilts divided in two series, housed as 10 pigs/pen. The 30 pigs per series were distributed between three pens (10 pigs/pen) and were balanced by body weight and litter. Throughout the entire weaner period all pigs had ad libitum access to the same diet. Pigs were redistributed among the grower-finisher pens to balance FCR levels between dietary treatments (CP levels) and to reduce any carry over effect from the weaner to the grower-finisher pens. From 30-115 kg body weight (BW), pigs were fed either a low (L; 14.8% CP), standard (15.2% CP) or high (H; 15.8% CP) CP diet equal in energy, where BW, average weekly gain (AWG), and FCR were determined on weekly basis, while FI was estimated on daily basis. Three low FE (20% least) and three high FE (20% greatest) pigs were selected based on the final 4 wk of growth within station and CP level. On the final day of the experimental period all low-FE and high-FE pigs within each dietary treatment were euthanized and blood plasma was sampled and subjected to a nontargeted LC-MS metabolomics analysis. Growth performance and metabolite data were, respectively, analyzed in R and MetaboAnalyst 5.0 with FE and CP as fixed effects. High-FE and H-CP pigs continuously displayed numerically greater BW, while AWG and FCR were, respectively, numerically greater, and less in L-CP than H-CP group during last 2 wk of the experimental period. Principal Component Analysis (PCA) showed no grouping (P &amp;gt; 0.05) of metabolites and no specific pattern of the metabolic profile from either the two FE categories or the three dietary CP levels. Furthermore, no correlation (P &amp;gt;0.05) of metabolites to any other observation was found, and only little variation, measured by distance to model showing deviation of each pig to overall model, was observed. In conclusion, at first glance the metabolomics profile did not appear to present any specific pattern between low and high feed efficiency grower-finisher pigs or between pigs exposed to different levels of dietary CP in the grower finisher period.

PSVI-19 No apparent association between the microbiome in the distal part of the small intestine and feed efficiency in grower-finisher pigs fed three different levels of dietary crude protein

Abstract Improving feed efficiency (FE) of grower-finisher pigs is important considering its production, environmental and climate impact. The biological background describing variation in FE between pen mates, is difficult to establish as feed intake (FI) and FE is not estimated on an individual level. In this study advanced feeding stations were used to estimate FI and further calculate feed conversion ratio (FCR) on individual level. The study aimed to investigate the possible association between FCR and microbiome (alpha and beta diversity; observed features and Shannon index, and Bray-Curtis dissimilarity and Jaccard Distance) in the distal part of the small intestine (SI) in grower-finisher pigs fed three different levels of dietary crude protein (CP). The study included 60 newly weaned gilts divided in two series, housed as 10 pigs/pen. The 30 pigs per series were distributed between three pens (10 pigs/pen) and were balanced by body weight (BW) and litter with ad libitum access to the same diet. Pigs were redistributed among the grower-finisher pens to balance FCR levels between dietary treatments (CP levels) and to reduce any carry over effect from the weaner to the grower-finisher pens. From 30-115 kg BW, pigs were fed either a low (L; 14.8% CP), standard (Std; 15.2% CP) or high (H; 15.8% CP) CP diet equal in energy, where BW, average weekly gain (AWG), and FCR were determined on weekly basis, while FI was estimated on daily basis. Three low FE (20% least) and three high FE (20% greatest) pigs were selected based on the final 4 wk of growth within station and CP level. All low-FE and high-FE pigs within each dietary treatment were euthanized around 115 kg BW and content and mucosa scrabe from the distal part of the SI was sampled and subjected to 16S rRNA gene amplicon sequencing. Data were analyzed in R using a generalized linear mixed-effects model with FE, CP, and their interaction as explanatory variables, start BW of weaner and grower phase as covariables, and series as random effect. High-FE and H-CP pigs continuously displayed numerically greater BW, while AWG and FCR were, respectively, numerically greater, and less in L-CP than H-CP group during last 2 wk of the experimental period. While FE and CP individually had no significant impact [Pr(&amp;gt; Chisq] &amp;gt; 0.05), their interaction could be important in explaining the variation (Chisq = 6.42, Df = 2, Pr(&amp;gt;Chisq) = 0.04) as expressed by observed features. But a pairwise comparison with a Benjamini–Hochberg correction showed no difference between groups. Concerning the Shannon index, no significance was found between groups, and no difference with respect to beta diversity was observed. In conclusion, the microbiome as expressed by alpha and beta diversity did not explain the variation between low and high FE in grower-finisher pigs.

97 Effects of crude protein content and supplementing probiotics in late gestation and lactation sow diets on performance of sows and suckling pigs

Abstract The objective of this study was to investigate the effects of crude protein (CP) content and supplementation with Bacillus-based probiotics (PRO) in late gestation and lactation sow diets on performance of sows and suckling pigs. Pregnant sows (n = 120; 60 gilts and 60 2+ parity) were assigned to 4 dietary treatments in a 2 x 2 factorial arrangement (2 CP levels, with or without probiotics) from d 85 of gestation to d 21 of lactation. The experiment was conducted in 4 consecutive periods (half sows and half gilts per period). The diets consisted of 1) a corn-soybean meal (SBM)-based low CP (LCP; 12% CP) diet; 2) LCP + 0.05% probiotic (LCP-PRO); 3) a corn-SBM-based high CP (HCP; 15% CP) diet; and 4) HCP + 0.05% probiotic (HCP-PRO). The diets were formulated for 2 phases: gestation (d 85 – 115) and lactation (d 1 – 21). Sow body weight (BW) and backfat thickness were recorded on d 85 and 111 of gestation and on d 1 and 21 of lactation. Sow blood and milk were sampled on d 1 and 21 of lactation to analyze plasma urea nitrogen (PUN) concentration, and milk fat, protein, and lactose, respectively. Data were analyzed using the PROC MIXED of SAS. The statistical model included diet as fixed effect and period as random effect. There were no significant effects of CP and PRO on sow BW or backfat thickness. There was an interaction (P &amp;lt; 0.05) between CP and PRO on the number of stillbirths, where the number of stillbirths did not differ between LCP and LCP-PRO groups, while the number decreased in sows fed HCP-PRO diet compared with HCP diet. Sows fed LCP diets had reduced (P &amp;lt; 0.05) PUN concentrations on d 1 and d 21 of lactation compared with those fed HCP diets. However, no difference was found in fat, protein, or lactose content in both colostrum (d 1) and milk (d 21). Piglets from the sows fed LCP diets showed heavier (P &amp;lt; 0.05) birth weights (1.58, 1.57, 1.53, and 1.52 kg for diets 1 to 4) than those in HCP groups, however, the average daily gain (ADG) of week 1 (188, 166, 187, and 187 g for diets 1 to 4) was less (P &amp;lt; 0.05) for piglets in LCP groups than HCP groups. No other effects were observed on piglet growth. In conclusion, CP and PRO did not affect sow BW and backfat thickness. There was an interaction effect of CP and PRO on reproductive performance, where stillbirths did not differ between LCP and LCP-PRO groups; however, stillbirths decreased with PRO in HCP diet. Moreover, feeding LCP diets to sows did not influence milk nutrient contents and overall growth performance in suckling piglets.

176 Impact of dietary crude protein level and water-based arginine on piglet growth and scouring with an Enterotoxigenic Escherichia coli F18 challenge

Abstract The objective of this experiment was to evaluate the impact of dietary crude protein (CP) level and water-based arginine (Arg) on the growth performance and scouring of piglets post wean and following an enterotoxigenic Escherichia coli F18 infection (ETEC). A total of 240 pigs (PIC 337 x 1050, Genus, Henderson, TN) were randomly assigned to 40 mixed-sex pens (6 pigs/pen) for a 6-wk experiment. At arrival, all pigs were genotyped for fructosyltransferase (FUT1). Pens were assigned to one of four treatments in a 2 x 2 factorial, with two crude protein levels (standard: 23% vs. low: 19.5%, for period 1) and two water treatments (absence or presence (8, 6, and 4% stock dosed through 1:128 proportioner for wk 1, 2, and 3, respectively) of Arg in water. Pig body weight (BW), feed disappearance (average daily feed intake; ADFI), and feed conversion (gain to feed ratio; G:F) were evaluated for four periods: d 0-7, 7-14, 14-21, and 21-42. Scour scores were recorded daily for the first 28 d to calculate weekly percentage of days scouring (scouring percentage). On d 21, water and dietary treatments ceased, and pigs received a common diet. All pigs were orally inoculated with a field strain of ETEC for two consecutive days on d 15 and 16 of the experiment. One pig per pen had blood collected (8mL via jugular) and was euthanized on d 14 before ETEC. Blood was collected via a jugular vein from another pig confirmed to be susceptible to ETEC on d 15, 17, and 22. The same pig was euthanized for tissue collection on d 22. Fecal swabs from 1 susceptible pig per pen were collected on d 15, 17, 19, and 22 for measurement of ETEC shedding. Blood samples were analyzed for inflammatory markers, and villi: crypt within the ileum were measured. Data were analyzed using mixed model methods (SAS 9.4, Cary, NC) with pen as the experimental unit. Growth performance and scouring percentage included the fixed effects of CP level, water treatment, experimental period, and their interactions. Reducing the CP of diets reduced the overall G:F of pigs (P &amp;lt; 0.01, standard: 0.73, low: 0.71). The percentage of days scouring tended to be influenced by the interaction between water and period (P = 0.06); specifically, when arginine (Arg) was present in the water, there was a numerically greater scouring percentage for all periods, except for the final period (d 21-28). Confirming the success of the ETEC challenge, period significantly impacted scouring percentage (P &amp;lt; 0.01), where piglets experienced the greatest scouring percentage (59%) during the week following ETEC inoculation, compared with the least in the week preceding inoculation (22%). In conclusion, low CP diets reduced overall G:F, but neither CP or Arg showed benefit in terms of scouring.

196 Effects of zinc source and level in low ABC-4 diets on nursery pig growth performance and fecal dry matter

Abstract Incorporating pharmacological levels of Zn in nursery pig diets is a well-recognized practice for reducing post-weaning diarrhea, enhancing growth performance, and enhancing gut health. We hypnotized that the use of a specific form of ZnO (small aggregates and agglomerated particles; SAAP), which provides a greater antibacterial property than standard ZnO, could be added at reduced levels without compromising piglet performance. This study aimed to explore the effects of different levels of SAAP Zn source (HiZox, Animine, France) in low ABC-4 diets with low or high CP content. A total of 360 weanling barrows [DNA 200 × 400, initial body weight (BW) = 5.9 ± 0.4 kg] were used in a 38-d experiment. Pigs were randomly assigned to pens (5 pigs/pen) and pens assigned to 1 of 6 treatments with 12 pens/treatment. The experiment consisted of phase 1 from d 0 to 10, phase 2 from d 11 to 24, and phase 3 from d 25 to 38. Treatments consisted in a negative control (NC), which had 150 ppm of Zn (HiZox) throughout the experiment and the remaining treatments were: positive control (PC) containing 3,000 ppm (phase 1) and 2,000 ppm (phase 2) of Zn provided by ZnO; low-HiZox containing 500 ppm (phase 1) and 300 ppm (phase 2) of Zn; low-HiZox-low-CP was similar to low-HiZox but contained less CP (19.3%) than the NC, PC, low and high-HiZox diets (21.3%); high-HiZox containing 800 ppm (phase 1) and 500 ppm (phase 2) of Zn; and high-HiZox-low-CP was similar to high-HiZox but contained 19.3% CP. In phase 3, all pigs were fed a common diet containing 150 ppm of Zn (HiZox) and high CP. For the experimental period (d 0 to 24), average daily gain (ADG; quadratic, P = 0.007) and average daily feed intake (ADFI; quadratic, P = 0.018) increased as HiZox increased (Table). Pigs fed high-HiZox-low-CP had poorer gain to feed ratio (G:F; P &amp;lt; 0.05) than NC, PC, low-HiZox, and high-HiZox. Additionally, in both experimental and overall periods, pigs fed diets with low CP had decreased G:F (P = 0.043) than those fed the same Zn levels but with high CP. Overall, pigs fed high-HiZox-low-CP had decreased G:F than pigs fed high-HiZox only (732 vs. 761 g/kg, respectively; P &amp;lt; 0.05), with other treatments intermediate. For fecal dry matter (DM), pigs fed low CP diets had greater (P = 0.008) DM compared with pigs fed high CP. Thus, the inclusion of HiZox at 800 and 500 ppm in phases 1 and 2, respectively, in a low-ABC-4 diet might be a strategy to reduce the use of pharmacological levels of Zn from ZnO in nursery diets.

Circadian rhythm of salivary and serum urea concentration in alpacas and sheep receiving diets with different levels of protein.

All vertebrates possess a daily rhythm, encompassing a comprehensive set of physiological, cognitive, and behavioral patterns that manifest throughout a 24-hour period. The aim of this study was to compare the effect of crude protein (CP) levels in the diet on the daily rhythm of urea in serum (US) and saliva in alpacas and sheep. Ten alpacas and ten sheep, adult, clinically healthy males, were used; they were maintained in natural light conditions and fed ad libitum with two levels of CP (16 and 7%). Blood and saliva samples were taken every 4h for 48h. A two-way ANOVA was conducted to analyze the parameters, including adjusted mean rhythm (MESOR), amplitude, and acrophase. It was found that both US and saliva urea exhibited circadian rhythms with a peak during the midday (10:59 - 12:16h). The MESOR with low CP diets was higher (P < 0.05) in alpacas. The MESOR of urea levels in saliva was greater (P < 0.05) at the highest level of CP in the diet, with no differences between alpacas and sheep (P > 0.05). The amplitude was greater (P < 0.05) in alpacas and at the high level of CP compared to the low level of CP in the diet. Our findings reveal that both serum and saliva urea levels in alpacas and sheep follow a daily rhythm and the MESOR of US was higher in alpacas when they consume food with low CP content, and this difference disappears when CP levels are increased in the diet.

Effect of Achyranthes japonica extract on growth, digestibility, microbiota, gas emission, and meat quality in broilers fed different protein diets.

Achyranthes japonica extract (AJE) is a multifuctional products that express anti-inflammatory, antioxidant and anti-microbial properties. This study was aimed to evaluate the effects of AJE addition to standard and low crude protein (LCP) diet on growth performance, nutrient digestibility, excreta bacterial count, excreta noxious gas emissions, breast meat quality, and organ weight of broiler chicken. A total of 340 one-day-old Ross 308 broilers [initial body weight (BW) of 43.10 ± 1.46 g, 5 replicate cages per treatment, and 17 birds per cage] were randomly distributed into 1 of 4 dietary treatment groups for a 35 day trial. The diets were provided based on three age stage of the broiler. In the starter stage broiler were fed basal diet. Experimental diet were fed to broiler from day 8 to 35. In growing (days 8-21) and finishing (days 22-35) stage broiler were fed: Standard crude protein (SCP) diet and LCP diet with 0.025% and 0.05% of AJE supplementation respectively. Here, the SCP and LCP diets were 21.50% and 20.86% CP during days 8-21 and 20.00% and 19.40% CP during days 22-35, respectively. The SCP diets with 0.025% AJE supplementation resulted in higher (p < 0.5) BW gain (BWG) at finishing stage and a tendency to lower feed conversion ratio and BWG in the overall period compared to LCP diets with or without AJE supplemenation. Moreover, dry matter and nitrogen digestibility were increased with SCP diet along with 0.025% of AJE. No significant difference was found in meat quality parameters except for pH. Interestingly, the NH3 gas emission to the environment was found to be less with different levels of CP and AJE supplementation. Therefore, we concluded that the addition of 0.025% AJE to the SCP diet improved broiler growth performance and nutrient digestibility with low fecal NH3 emissions.