Supplementation of protease to low amino acid diets containing superdose level of phytase for wean-to-finish pigs: effects on performance, postweaning intestinal health and carcass characteristics.

This experiment investigated the effects of protease supplementation to low amino acid (AA) diets containing phytase on pig growth performance, postweaning intestinal health and carcass characteristics. A total of 936 weaned pigs (21 d of age, initial BW 5.87 ± 0.31 kg) were used in a 2 × 2 factorial design comparing the main effects of AA supply [standard feeding program: balanced for all nutrients with adjustment of Ca and P due to inclusion of phytase (2,500 FTU/kg in Phase 1 to 4; 500 FTU/kg in Phase 5 to 9) vs. low AA feeding program: 15% lower standardized ileal digestible lysine with relative reduction of all other essential AA] and protease level (0 vs. 0.0125%). Pens were assigned to dietary treatment according to a randomized complete block design with 26 pigs per pen and nine replicates per dietary treatment. Feed and water were provided on an ad libitum basis for all phases throughout the wean-to-finish period. Feed intake and body weight were determined every 2 wk during nursery period and monthly in the grow-finish period. Intestinal health in the first 17 d was assessed based on lactulose:mannitol ratio (L:M), serum IgA, and pen diarrhea assessment. Overall, pigs fed standard wean-to-finish diets had greater (P < 0.05) ADG and G:F than pigs fed low AA diets. Pig growth performance was not different throughout the wean-to-finish period with or without protease supplementation and with no interaction between AA supply and protease supplementation. There were no differences among dietary treatments for carcass characteristics. No difference was observed for urinary L:M and serum IgA; however, the L:M ratio was approximately 32% lower in pigs fed low AA diets + protease compared with pigs fed standard and low AA diets at d 5 and d 17 postweaning. Pigs fed protease supplemented diets had lower incidence of diarrhea (χ 2 < 0.05) compared with pigs fed diets without protease. Results of the experiment indicate that dietary protease supplementation benefits intestinal health of nursery pigs.

Comparative analysis of the ileal bacterial composition of post-weaned pigs fed different high-quality protein sources.

To further understand the contribution of feedstuff ingredients to gut health in swine, gut histology and intestinal bacterial profiles associated with the use of two high-quality protein sources, microbially enhanced soybean meal (MSBM) and Menhaden fishmeal (FM) were assessed. Weaned pigs were fed one of three experimental diets: (1) basic diet containing corn and soybean meal (Negative Control (NEG)), (2) basic diet + fishmeal (FM; Positive Control (POS)) and (3) basic diet + MSBM (MSBM). Phase I POS and MSBM diets (d 0 to d 7 post-wean) included FM or MSBM at 7.5%, while Phase II POS and MSBM diets (d 8 to d 21) included FM or MSBM at 5.0%. Gastrointestinal tissue and ileal digesta were collected from euthanised pigs at d 21 (eight pigs/diet) to assess gut histology and intestinal bacterial profiles, respectively. Data were analysed using Proc Mixed in SAS, with pig as the experimental unit and pig (treatment) as the random effect. Histological and immunohistochemical analyses of stomach and small intestinal tissue using haematoxylin-eosin, Periodic Acid Schiff/Alcian blue and inflammatory cell staining did not reveal detectable differences in host response to dietary treatment. Ileal bacterial composition profiles were obtained from next-generation sequencing of PCR generated amplicons targeting the V1 to V3 regions of the 16S rRNA gene. Lactobacillus-affiliated sequences were found to be the most highly represented across treatments, with an average relative abundance of 64.0%, 59.9% and 41.80% in samples from pigs fed the NEG, POS and MSBM diets, respectively. Accordingly, the three most abundant Operational Taxonomic Units (OTUs) were affiliated to Lactobacillus, showing a distinct abundance pattern relative to dietary treatment. One OTU (SD_Ssd_00001), most closely related to Lactobacillus amylovorus, was found to be more abundant in NEG and POS samples compared to MSBM (23.5% and 35.0% v. 9.2%). Another OTU (SD_Ssd_00002), closely related to Lactobacillus johnsonii, was more highly represented in POS and MSBM samples compared to NEG (14.0% and 15.8% v. 0.1%). Finally, OTU Sd_Ssd-00011, highest sequence identity to Lactobacillus delbrueckii, was found in highest abundance in ileal samples from MSBM-fed pigs (1.9% and 3.3% v. 11.3, in POS, NEG and MSBM, respectively). There was no effect of protein source on bacterial taxa to the genus level or diversity based on principal component analysis. Dietary protein source may provide opportunity to enhance presence of specific members of Lactobacillus genus that are associated with immune-modulating properties without altering overall intestinal bacterial diversity.

Nutritive value of multienzyme supplemented cold-pressed camelina cake for pigs.

Cold-pressed camelina cake (CPCC) is a fibrous co-product of camelina seed pressing and available for livestock feeding. However, information is lacking on the effect of supplementing fiber-degrading enzymes to CPCC-based diets on nutrient utilization by pigs. Experiment 1 determined the effect of multienzyme supplementation on standardized ileal digestibility (SID) of amino acid (AA) and net energy (NE) value of CPCC for pigs. Six ileal-cannulated barrows (average initial body weight [BW] = 36 kg) were fed five diets in 5 × 5 Latin square design with 1 added column to give six replicates per diet. The diets were a corn-soybean meal (SBM)-soybean oil-based diet and the basal diet with corn, SBM, and soybean oil replaced by 25% CPCC with or without multienzyme (600 U of xylanase, 75 U of glucanase, 250 U of cellulose, 30 U of mannanase, 350 U of invertase, 2,500 U of protease, and 6,000 U of amylase/kg of diet; Superzyme-CS, 0.5 g/kg) in a 2 × 2 factorial arrangement. The fifth diet was a low-casein cornstarch-based diet. The ratio of corn to SBM and soybean oil in the basal diet was identical to the CCPC-containing diets to allow calculation of nutrient digestibility of CPCC by the difference method. On a dry matter (DM) basis, CPCC contained 42% crude protein, 10.5% ether extract, 25.4% neutral detergent fiber (NDF), 2.07% Lys, 0.73% Met, 1.64% Thr, 0.51% Trp, and 22.1 trypsin inhibitor units per milligram, respectively. The SID of Lys, Met, Thr, and Trp for CPCC were 43.5%, 70.7%, 44.8%, and 55.3%, respectively. The digestible energy (DE) and NE values for CPCC were 3,663 and 2,209 kcal/kg of DM, respectively. Multienzyme supplementation did not affect the SID of AA, and DE and NE values for the corn-SBM-CPCC-based diet, and for the CPCC. In experiment 2, the effects of multienzyme dosage (0.5 or 50 g/kg of treated feedstuff) on porcine in vitro digestibility of DM (IVDDM) of CPCC was determined. The IVDDM of CPCC was increased (P < 0.001) with an increase in multienzyme dosage. Multienzyme at 0.5 g/kg did not affect IVDDM of CPCC. However, multienzyme at 50 g/kg increased (P < 0.01) IVDDM for CPCC by at least 16%. In conclusion, multienzyme at 0.5 g/kg did not affect SID of AA and NE values, and IVDDM for CPCC. However, multienzyme at 50 g/kg improved IVDDM of CPCC, implying that the efficacy of the multienzyme with regard to improving nutrient digestibility of CPCC in pigs is dosage dependent.

Dynamics of nitrogen retention at two feeding levels in gestating parity 2 and 3 sows.

Parity-2 ( = 39) and -3 ( = 28; same sows from parity-2 sows) Yorkshire sows were used to measure whole body protein deposition (Pd) during gestation (maternal and pregnancy-associated) at 2 feeding levels to test the hypothesis that the pattern of whole body and maternal Pd during gestation does not differ when feeding either 15% above or 15% below estimated ME requirements, both exceeding AA requirements. Initial BW and backfat (BF) at d 26 ± 0.3 of gestation were 195.4 ± 5.2 kg and 15.1 ± 0.5 mm, and 223.1 ± 5.3 kg and 16.0 ± 0.6 mm for parity-2 and -3, respectively. Sows were assigned to 1 of 2 feeding levels (high and low; 15% above and 15% below estimated ME requirements, respectively) of the same diet (3.30 Mcal ME/kg, 17.8% CP, 0.82% SID Lys) from d 31 to 110 of each gestation cycle. Five N balances were conducted throughout each gestation starting at d 36, 51, 65, 85, and 106 ± 0.5 during 4-d periods. Pregnancy-associated Pd was model-derived for each sow and N balance period using the gestating sow model, based on actual litter size (including stillborn) and mean piglet birth weight. Maternal Pd was calculated as the difference between whole body and pregnancy-associated Pd. Whole body Pd and maternal Pd were greater ( 0.002) for sows on the high feeding level. Whole body Pd increased ( 0.001) with day of gestation and maternal Pd did not differ with day of gestation. Whole body and maternal Pd were greater ( ≤ 0.004) for parity-3 sows from d 51 to 54 and 85 to 88 of gestation only. Estimated efficiency of Lys retention for whole body Pd was not different between the 2 feeding levels, greater ( 0.016) for parity-3 sows, and increased quadratically ( 0.027) with day of gestation. During lactation (21.3 ± 0.3 d), there was no effect on sow ADFI and minimal effect on litter performance due to gestation feeding level or parity. Sows on the high feeding level had greater ( 0.009) BW and BF loss during lactation and these parameters were not affected by parity. Feeding 15% above estimated ME requirements during gestation resulted in consistently greater whole body and maternal. Whole body and maternal Pd were particularly greater for parity-3 sows from d 51 to 54 and 85 to 88 of gestation. The pattern of maternal Pd, regardless of feeding level, was not affected by day of gestation and is in contrast to , where maternal Pd is expected to be greater in early gestation.

Evaluation of a bioprocessed soybean meal on nursery pig performance and immune status.

A total of 239 pigs (initial BW 6.56 ± 0.87 kg, 21 d of age) were used in a 35-d study to investigate the effects of fish meal (FM) and spray dried plasma (SDP) in combination with a bioprocessed soybean meal (SBM) on growth performance and immune responses in weaned pigs. Equal numbers of barrows and gilts were randomly allotted to 1 of 4 dietary treatments (10 pens/treatment) according to initial BW and sex: positive control (CON; corn/SBM diet) containing SDP and FM, the CON with bioprocessed SBM replacing FM (BPSBM), the CON with bioprocessed SBM replacing SDP (BPSBM), and the CON with bioprocessed SBM replacing both SDP and FM (BPSBM). Experimental diets were fed in Phase I (d 1-7 post-wean) and II (d 8-21) followed by a common Phase III diet (d 22-35); changes in BW and feed disappearance were determined accordingly. Pigs were sensitized against ovalbumin (OVA) and Candida albicans (CAA) on d 7 and 21. Assessment of immune response was based on lymphocyte proliferation in response to mitogens Concanavalin A and phytohemagglutinin (d 14 post-wean), dermal hypersensitivity to OVA and CAA (% increase in local swelling at 2, 6, 24, and 48 h post-injection) on d 28, and primary and secondary anti-OVA IgG at d 21 and 28, respectively. Pigs fed CON were heavier (P < 0.01) than pigs fed BPSBM and BPSBM, and not different from pigs fed BPSBM, at the end of Phase I and II (6.99, 6.80, 6.52, or 6.60 kg, pooled SEM 0.08, respectively in Phase I or 12.47, 12.18, 11.42, and 11.85 kg, pooled SEM 0.21, in Phase II, respectively). Hypersensitivity to OVA peaked at 2h in pigs fed CON, BPSBM, and BPSBM or peaked at 6h in pigs fed BPSBM (121.4, 165.6, 139.0, and 144.1%, pooled SEM 22.9, respectively, at 2 h and 86.7, 114.5, 95.0, and 156.8%, pooled SEM 29.4, respectively at 6 h). Peak response to CAA occurred at 2h in all groups (42.6, 55.2, 48.2, and 50.6%, pooled SEM 11.9, respectively, in the CON, BPSBM, BPSBM, and BPSBM, respectively). There was no difference in hypersensitivity due to experimental diet at any time point. Secondary anti-OVA IgG was 2-fold lower based on optical density values in pigs fed CON compared with BPSBM and BPSBM (0.78 vs. 1.56 and 1.55 optical density at 405 nm, pooled SEM 0.42, respectively). Dietary treatment did not impact lymphocyte proliferation. The bioprocessed SBM is a suitable alternative for FM and/or SDP in Phase I and II nursery diets based on pig growth. The prolonged hypersensitivity to OVA indicate that bioprocessed SBM may have a positive impact on pig immune function and the 2-fold increase in anti-OVA IgG warrants further investigation on the impact of bioprocessed SBM on pig immune function.

Evaluation of microbially enhanced soybean meal as an alternative to fishmeal in weaned pig diets.

An experimental, microbially enhanced soybean product (MEPRO) was evaluated as a replacement for fishmeal (FM). Assessment of feedstuffs should include estimation of digestibility as well as pig performance and in combination with dietary additives. Digestibility values determined in growing pigs may not apply to nursery pigs; thus, standardized ileal digestibility (SID) of amino acids (AA) in MEPRO and FM were determined using 30±1.6 kg BW ileal-cannulated barrows (n=6) and 9.8±1.2 kg BW barrows (n=37; serial slaughter). Experimental diets included MEPRO, FM and nitrogen free where FM and MEPRO were included as the sole protein source. The SID of AAs was 3% to 5% lower in MEPRO than FM when fed to 30 kg pigs. The SID of arginine and methionine was greater (P<0.05) in MEPRO than FM when fed to 10 kg pigs. The SID of AAs was 12% to 20% lower in FM when fed to 10 v. 30 kg pigs but only 3% to 9% lower in MEPRO. A total of 336 barrows and gilts were weaned at 21 days of age (initial BW=6.1±0.8 kg) and used in a performance trial. Pens of pigs were assigned to one of the six experimental diets (8 pens/diet in two blocks). Treatment diets were fed in Phase I (7 days) and Phase II (14 days) with all pigs fed a common Phase III diet (14 days). Experimental diets included (1) negative control (NEG) containing corn, soybean meal and whey, (2) NEG+acidifier, (3) NEG+FM (POS), (4) POS+acidifier (POS A+), (5) NEG+MEPRO (MEPRO) and (6) MEPRO+acidifier. The FM and MEPRO were included at 7.5% and 5.0% in Phase I and II diets, respectively. Diets were formulated to meet the standard nutrient requirements for weaned pigs. Pig BW and feed disappearance was measured weekly and fecal scores were measured daily for the first 14 days post-weaning as an indicator of post-weaning diarrhea syndrome (PWDS). Performance (BW, daily gain, feed intake and gain : feed) was not significantly different among treatments. Treatment for PWDS occurred on different days in each block. Analysis of fecal score was completed separately by block. Pigs fed the NEG diets had higher (P=0.02) fecal scores than pigs fed the POS diets on days 2 and 3 (block 1) and higher (P<0.05) than pigs fed MEPRO or POS diets and diets with dietary acidifier on days 6 and 3 (block 2). The MEPRO holds promise as an alternative to FM in nursery pig diets.

Dynamics of nitrogen retention in gestating gilts at two feeding levels.

Whole-body protein deposition (Pd) is a main determinant of AA requirements of gestating gilts; however, data on the dynamics of Pd is limited. The main objective of this study was to measure whole-body Pd (pregnancy-associated and maternal) during gestation in gilts at 2 feeding levels. Changes in BW and backfat (BF) throughout gestation and subsequent lactation performance were also evaluated. We hypothesized that the effect of feed intake on maternal Pd decreases toward the end of gestation due to increased fetal nutrient demands. Fifty-one pregnant Yorkshire gilts (initial BW and BF at d 28 ± 0.5 of gestation were 168.6 ± 2.2 kg and 16.9 ± 0.8 mm, respectively) were used. Gilts were assigned to 1 of 2 feeding levels (high feeding level and low feeding level; 2.54 and 1.87 kg/d, respectively) of the same diet (3.30 Mcal ME/kg, 17.8% CP, 0.82% standard ileal digestible Lys) from d 33 to 112 ± 0.5 of gestation. Nitrogen balance observations (based on total urine collection with urinary catheters and determination of fecal N digestibility using an indigestible marker) were made at 5 distinct time periods, each 4 d in length, starting at d 38, 52, 66, 87, and 108 ± 0.5 of gestation. Pregnancy-associated Pd (fetus, mammary gland, uterus, and placenta and fluids) was calculated for each gilt and N balance period using the gestating sow model, based on actual litter size (including stillborns) and mean piglet birth weight. Maternal Pd was calculated as the difference between whole-body Pd and pregnancy-associated Pd. Across all N balance periods, whole-body and maternal Pd were consistently 40.1 ± 5.2 g/d greater ( < 0.001) for the high feeding level compared with the low feeding level. At both feeding levels, whole-body Pd increased (linear and quadratic, < 0.020) with day of gestation and maternal Pd decreased (cubic, < 0.010) with day of gestation. During lactation, maternal voluntary feed intake and litter performance were not affected by gestation feeding level. Gilts on the high feeding level lost more BW and BF during lactation ( ≤ 0.030). In summary, the effect of feeding level on whole-body and maternal Pd was constant throughout gestation. However, the gradual decline in maternal Pd with day of gestation is in contrast to that reported by the and has important implications for the factorial estimation of AA requirements of gestating gilts toward the end of gestation.

Nutritive value of extruded or multi-enzyme supplemented cold-pressed soybean cake for pigs.

The objectives were to determine the standardized ileal digestibility (SID) of AA and NE value of cold-pressed soybean cake (CP-SBC), and the effect of extrusion or adding multi-enzyme to CP-SBC diet for growing pigs. Eight ileal-cannulated pigs (initial BW = 79.7 ± 3.97 kg) were fed 4 diets in a replicated 4 × 4 Latin square design to give 8 replicates per diet. Diets included a cornstarch-based diet with CP-SBC, extruded CP-SBC, and SBC plus multi-enzyme (1,200 U of xylanase, 150 U of glucanase, 500 U of cellulase, 60 U of mannanase, 700 U of invertase, 5,000 U of protease, and 12,000 U of amylase/kilogram of diet; Superzyme-CS, 0.5 g/kg); and a N-free diet. The CP-SBC was the sole source of protein in the CP-SBC-containing diets. The ratio of cornstarch to sugar and soybean oil in CP-SBC-containing diets was identical to the N-free diet to allow calculation of energy digestibility of CP-SBC by the difference method. The evaluated CP-SBC had been produced by heating the soybean seed at 105°C for 60 min followed by pressing of the heated soybean seeds at less than 42°C (barrel temperature). On a DM basis, CP-SBC and extruded CP-SBC contained 47.8 and 47.1% CP, 15.6 and 10.5% ADF, 7.23 and 8.85% ether extract, 3.11 and 3.08% Lys, and 2.25 and 3.70 trypsin inhibitor units per mg, respectively. Extrusion increased ( < 0.001) the SID of AA for the CP-SBC by an average of 12%. Also, extrusion increased ( < 0.001) the NE value of the CP-SBC from 2,743 to 2,853 kcal/kg of DM. Supplementation of CP-SBC diet with the multi-enzyme increased ( < 0.05) the SID of Arg and Pro, and tended to increase ( < 0.1) the SID of Ile and Tyr. However, the multi-enzyme supplementation did not affect the NE value of CP-SBC. In conclusion, the CP-SBC evaluated in the present study could be an alternative source of AA and energy in swine diets, and its nutritive value can be increased by extrusion following cold-pressing. The multi-enzyme used in this study improved the digestibility of some AA, but had limited effect on energy digestibility and hence NE value of the CP-SBC.

Impact of nursery feeding program on subsequent growth performance, carcass quality, meat quality, and physical and chemical body composition of growing-finishing pigs.

An experiment was conducted to examine the effect of the nursery feeding program on subsequent growth performance, carcass quality, meat quality, and physical and chemical body composition of growing-finishing pigs. Four dietary treatments were used in a 2 × 2 factorial arrangement of treatments based on diet complexity (Complex vs. Simple) and in-feed antibiotics (2,730 [+AB] vs. 0 [-AB] mg of chlortetracycline /kg].A total of 552 pigs, in 5 blocks, were weaned at 21 ± 2 d of age with an initial BW of 7.03 ± 0.07 kg. Each experimental block had 3 pens per treatment, with 8 pigs per pen in blocks 1 and 2, and 10 pigs per pen in the remaining 3 blocks. Nursery diets were fed in a 3-phase feeding program (Phase I, II, and III diets fed for 1, 2, and 3 wk, respectively). All pigs were fed common grower-finisher diets thereafter. Six pigs per treatment were slaughtered for chemical body composition analysis at wk 2, 8, 12, and 17 postweaning. An additional 11 pigs per treatment were slaughtered at wk 17 postweaning (approximately 115 kg BW or market weight) for analysis of carcass characteristics, chemical and physical body composition, and meat quality. During the nursery phase, ADG was lower (P < 0.05) for pigs fed the Simple diet than those fed the Complex diet (491 vs. 528 g/d). Antibiotic usage improved (P < 0.05) ADG in Phases II (408 vs. 438 g/d) and III (689 vs. 720 g/d). In Phase I and II, G:F was lower (P < 0.05) for pigs fed the Simple diet than those fed the Complex diet (0.46 vs. 0.58 and 0.75 vs. 0.78 in Phases I and II, respectively). During the grower phase, pigs previously fed -AB diets grew faster than pigs fed +AB diets (P < 0.05; 1,009 vs. 971 g/d). There were no treatment effects on overall ADG or G:F from weaning to finishing. Nursery feeding program did not affect carcass quality characteristics. However, pigs previously fed +AB diets tended (P = 0.07) to have increased LM depth. Nursery feeding program had no effect on objective or subjective meat quality measures, chemical body composition, or the weight of primal and retail carcass cuts at wk 17 postweaning, with the exception of primal belly weight. These results indicate that feeding simple nursery diets, or nursery diets without antibiotics, compromises growth performance during the nursery period but does not affect overall growth performance between weaning and market BW, carcass characteristics, and meat quality. Thus, feed costs for nursery pigs can be reduced by feeding simple diets without compromising market BW and carcass and meat quality.

Protein intake but not feed intake affects dietary energy for finishing pigs.

The effects of dietary protein and feeding levels on dietary metabolizable (ME) and net energy (NE) content were determined in 24 pigs, each offered two diets at 2.0 times the energetic maintenance requirement or for ad libitum intake between 55 and 95 kg body weight. Within feeding levels, pigs received, in random order, low-protein (LP; 11.2% CP, 0.61% lysine) or high-protein (HP; 20.2% CP, 0.61% lysine) diets of similar digestible energy content. Dietary NE was calculated from heat production based on 24-h indirect calorimetry following a 7-day N-balance period. Feed intake was greater for LP than HP when fed for ad libitum intake (p = 0.001). Protein level did not affect daily gain (p > 0.1) but HP improved gain: feed (p = 0.003). Dietary ME and NE were not significantly affected by feeding level but were decreased by high protein intake (p < 0.07). Reducing dietary protein reduced urinary energy losses and increased energy retention but did not affect heat production. The effect of dietary protein restriction was already evident on the ME level and carried over to a similar degree to the NE level because the utilization of ME was not affected by protein level. Dietary ME and NE decreased by 0.012 MJ/kg (p = 0.014) and 0.018 MJ/kg (p = 0.062), respectively, for each gram per day N intake. The results suggest that although there was an effect of protein level on NE, the greatest effect occurred at the level of ME. However, the prediction of both ME and NE may be improved by adopting energy values for dietary protein that changes with dietary protein content.

Immune system stimulation reduces the efficiency of tryptophan utilization for body protein deposition in growing pigs.

The effect of immune system stimulation (ISS) on N retention and Trp utilization in pigs fed Trp-limiting diets was evaluated using 36 growing pigs (20.0 ± 1.1 kg BW; 3 blocks of 12 barrows). Pigs were randomly assigned to 1 of 5 diets (Diet 1, 2, 4, and 5, n = 7; Diet 3, n = 8) and fed restrictively at 800 g/d. Diets 1 to 4 were generated by blending Diet 1 with a protein-free supplement and were calculated to contain varying amounts of standardized ileal digestible (SID) Trp (1.31, 1.05, 0.80, and 0.55 g/kg). To confirm that Trp was the first-limiting AA in Diets 1 to 4, an additional diet was used (Diet 5), which was equivalent to Diet 4 and contained 0.34 g/kg of added Trp. After a 5-d adaptation period, pigs were injected every 2 d with increasing amounts of E. coli lipopolysaccharide to induce ISS (initial dose 20 µg/kg BW, increasing 15% each subsequent injection). Whole body N balance was measured in 3 periods: before immune stimulation (pre-ISS) and during ISS in 2 subsequent periods (ISS-1, 3 d; ISS-2, 4 d). Regression analysis was used to estimate the marginal efficiency of Trp utilization for whole body protein deposition (PD; N retention × 6.25). Plasma concentrations of acute-phase proteins and white blood cell counts increased (P < 0.001) and plasma albumin decreased (P < 0.001) during ISS. Nitrogen retention increased (P < 0.001) as Trp intake increased. Nitrogen retention was numerically greater but not statistically different between Diet 5 (added Trp diet) and Diet 4. Whole body N retention was less (P < 0.05) during ISS due primarily to an increase (P < 0.05) in urinary N excretion. There was a linear response (P < 0.05) in N retention, urinary N, and total excreted N to increasing Trp intake. Protein deposition increased by 88.2 ± 5.2, 82.5 ± 5.1, and 92.5 ± 3.4 g/d for each additional g/d of SID Trp intake during pre-ISS, ISS-1, and ISS-2, respectively, but the intercept was not different (-32.3 g/d). The slope of the response of PD to increasing Trp intake (based on the common intercept) was less during ISS-1 compared with pre-ISS (P = 0.01) or ISS-2 (P = 0.002) but not different between pre-ISS and ISS-2. Immune system stimulation reduced N retention in pigs fed limiting dietary Trp. The efficiency of Trp utilization for protein deposition was also reduced during ISS, indicating that the Trp requirement for PD is increased ∼7% during an inflammatory state.

Dynamic changes in digestive capability may contribute to compensatory growth following a nutritional insult in newly weaned pigs.

We have previously demonstrated that feeding low complexity diets (LOW) compromises growth performance of pigs during the first 3 wk after weaning and induces compensatory growth and improved feed efficiency thereafter. A study was undertaken to explore physiological mechanisms involved in compensatory growth following a nutritional insult. Fifty-six pigs were weaned at 21 ± 2 d of age and fed high complexity diets (HIGH) for 6 wk. All pigs received the same grower diet thereafter. Pigs were killed at weeks 2, 4, and 8 after weaning and proximal jejunum and distal ileum were sampled for evaluation of histology and enzyme activity. In the proximal jejunum, villus height was lower (P = 0.03) at week 2 in pigs on LOW than HIGH but not different at week 4. There was no effect of diet on crypt depth; villus height:crypt depth ratio increased (P = 0.02) from week 2 to week 4 in pigs on LOW but was not changed in pigs on HIGH. Diet did not impact gut morphology at the distal ileum. Enzyme activity was lowest (P < 0.05) at week 2 for sucrase and aminopeptidase N (APN) and lowest (P < 0.06) at week 8 for lactase. Sucrase activity was numerically higher at week 4 in pigs fed LOW but numerically higher at week 8 in pigs fed HIGH. Lactase and APN activity were not affected by diet. Compensatory growth observed in pigs following a nutritional insult after weaning may be due in part to improved digestive capability.

Ileal mucosa-associated--but not ileal digesta--bacterial profiles in grower pigs are influenced by nutrition and use of antibiotics for weaner pigs.

A longitudinal study was conducted in pigs to evaluate the effect of nutrition and use of antibiotics for weaner pigs on ileal bacterial microbiota. Forty-eight pigs were weaned at 21 ± 2 d of age and fed a high complexity diet (High) or low complexity diet (Low) with chlortetracycline (A+) or without chlortetracycline (A-) for 6 wk. All pigs received the same grower diet thereafter. Pigs were killed at week 2, 4, and 8 and ileal digesta as well as a 40-cm section of the distal ileum were taken for extraction of digesta and mucosa-associated bacteria, respectively. Total DNA was extracted using a commercially available kit and PCR amplicons were generated using HDA1-GC and HDA2 primers against the V3 region of the 16S rRNA gene. Denaturing gradient gel electrophoresis (DGGE) of PCR amplicons was used for separation of distinct bacteria communities. Similarities of PCR-DGGE profiles were analyzed with Bionumerics software and the degree of similarity represented by a similarity coefficient. The DNA bands were compared using a positional tolerance of 0.5%. In the digesta, HighA-, LowA+, and LowA- were 47.6, 63.6, and 58.8% similar, respectively, at week 2 and 64.0, 69.2, and 66.7% similar, respectively, at week 4. Digesta bacteria were 90.9 (HighA-) and 85.7% (LowA-) similar to HighA+ at week 8 but due to a smiling edge of the DGGE gel, the profile for LowA+ was deemed inappropriate for similarity analysis. In the mucosa, HighA-, LowA+, and LowA- were 58.8, 80.0 and 44.4% similar, respectively, compared to HighA+ at week 2; 81.5, 75.0, and 88.9% similar, respectively, at week 4; and 81.8, 76.2, and 78.3% similar, respectively, at week 8. The bacterial profile was more similar between weeks 2 and 4 in the digesta than in the mucosa but more similar between weeks 4 and 8 in the mucosa than in the digesta. Postweaning nutrition may have a long-term effect on ileal mucosa-associated--but not ileal digesta--microbiota profiles.

The threonine requirement of sows increases in late gestation.

Current AA recommendations for sows are to provide a fixed amount of AA intake throughout gestation based on the assumption that there is a constant demand for AA; however, the demand for nutrients changes from maternal lean tissue in early gestation to fetal and mammary growth in late gestation. The objective of this study was to determine the Thr requirement in early (d 35 to 53 and 25 to 55 for Exp. 1 and 2, respectively) and late (d 92 to 110 and 81 to 111 for Exp. 1 and 2, respectively) gestation using the indicator AA oxidation (IAAO) method with l-[1-(13)C]Phe as the tracer AA. A total of 14 multiparous sows were used: 6 in Exp. 1 and 8 in Exp. 2. Each sow received each of 6 diets in random order in both early and late gestation. A basal diet was formulated to contain Thr at 60% of the 1998 NRC recommendation in Exp. 1 and 20 and 60% of the 1998 NRC in Exp. 2 for early and late gestation, respectively. Crystalline l-Thr was added to create additional diets with approximately 10% incremental increases in Thr. Sows were placed in respiration chambers, and expired air and blood were collected every 30 min for 5.5 h. Tracer Phe [mg/(kg of BW·h)] was given orally over the last 4 h divided into eight 0.5-h meals. Expired air and plasma were measured for (13)CO(2) enrichment and free Thr concentration, respectively. Background (13)CO(2) was subtracted from plateau (13)CO(2) enrichment. Data were analyzed using a 2-phase nonlinear Mixed model. The overall litter size and litter weight were 13.5 ± 3.1 and 20.5 ± 3.9 kg, respectively. Based on IAAO, the Thr requirement in early gestation was 6.1 g/d (R(2) = 0.59, Exp. 1) and 5.0 g/d (R(2) = 0.71, Exp. 2). In late gestation, the Thr requirement based on IAAO was 13.6 g/d (R(2) = 0.60, Exp. 1) and 12.3 g/d (R(2) = 0.58, Exp. 2). Based on plasma Thr, the Thr requirement in early gestation was 7.0 g/d (R(2) = 0.90, Exp. 1) and 3.9 g/d (R(2) = 0.90, Exp. 2). In late gestation, the Thr requirement based on plasma Thr was 10.5 g/d (R(2) = 0.67, Exp. 2). There was a linear response to increasing Thr intake in late gestation in Exp. 1. Feeding a single amount of AA throughout gestation results in overfeeding AA in early gestation and underfeeding AA in late gestation. The 2-fold increase in Thr requirement in the last third of gestation suggests that phase feeding sows in gestation will more closely meet the demands for nutrients and that the requirement for essential AA in gestating sows should be re-evaluated in early and late gestation separately.

The effects of dietary energy concentration and weaning site on weanling pig performance.

This study was conducted to evaluate the effects of dietary energy density and weaning environment on pig performance. Treatment diets were formulated to vary in DE concentration by changing the relative proportions of low (barley) and high (wheat, oat groats, and canola oil) energy ingredients. In Exp. 1, 84 pigs in each of 3 replications, providing a total of 252 pigs, were weaned at 17 x 2 d of age and randomly assigned to either an on-site or an off-site nursery and to 1 of 3 dietary DE concentrations (3.35, 3.50, or 3.65 Mcal/kg). Each site consisted of a nursery containing 6 pens; 3 pens housed 7 barrows and 3 housed 7 gilts. All pigs received nontreatment diets in phase I (17 to 19 d of age) and phase II (20 to 25 d of age), respectively. Dietary treatments were fed from 25 to 56 d of age. Off-site pigs were heavier at 56 d of age (23.4 vs. 21.3 kg; P < 0.05) and had greater ADFI (0.77 vs. 0.69 kg/d; P < 0.01) than on-site pigs. There was a linear decrease in ADG (P < 0.01) and ADFI (P < 0.001) with increasing DE concentration. Efficiency of gain improved (P < 0.01) with increasing DE concentration. There was no interaction between weaning site and diet DE concentration, indicating that on-site and off-site pigs responded similarly to changes in diet DE concentration. In Exp. 2, nutrient digestibility of the treatment diets used in Exp. 1 was determined using 36 pigs with either ad libitum or feed intake restricted to 5.5% of BW. Energy and N digestibility increased (P < 0.001) with increasing DE concentration. Nitrogen retention and daily DE intake increased with DE concentration in pigs fed the restricted amount of feed (P < 0.05). These results indicate that weaning off-site improves pig weight gain. The weanling pig was able to compensate for reduced dietary DE concentration through increased feed intake. Growth limitation in the weanling pig may not be overcome simply by increasing dietary DE concentration.