Two experiments were conducted to determine standardized ileal digestibility (SID) of amino acids (AA; Exp. 1) and net energy (Exp. 2) in two black soldier fly larvae meal (BSFLM) samples [full fat (FF; 42.5% crude protein (CP), as-fed) and defatted (DF; 40.8% CP; as-fed)] for growing pigs. Two cornstarch-based diets were formulated with FF and DF BSFLM as the sole sources of AA. A nitrogen-free diet was also used, and the corn starch:sucrose:oil ratio was kept constant among diets to calculate digestible energy (DE) by difference method. In each experiment, pigs were fed 2.8 × estimated maintenance energy requirement. In Exp. 1, eight ileal-cannulated barrows (25.1 ± 0.41 kg initial body weight) were used in a replicated 2 × 2 Latin square design (n = 8). In each period, pigs were adapted to diets for 5 d followed by 2 d of continuous ileal digesta collection for 8 h. The SID of AA were calculated using basal endogenous losses for pigs fed a nitrogen-free diet. In Exp. 2, eight barrows [23.4 ± 0.54 kg initial body weight (BW)] were used in a partially replicated Latin square design (n = 8). In each period, pigs were adapted to diets for 7 d, followed by 5 d of total urine collection and fecal grab sampling. The SID of CP (80.6 ± 1.1%) and Lys (88.0 ± 1.4%) were not different between FF and DF BSFLM. The SID of Arg, Val, Ala, and Pro tended to be less, and the SID of Met tended to be greater for the FF versus the DF BSFLM (P = 0.034, 0.090, 0.053, 0.065, 0.074, respectively). Digestible energy (4,927 vs. 3,941 ± 75 kcal/kg), metabolizable energy (4,569 vs. 3,396 ± 102 kcal/kg), and predicted net energy (3,477 vs. 2,640 ± 30 kcal/kg, using equations from Noblet; 3,479 vs. 2,287 ± 28 kcal/kg, using equations from Blok, respectively) were greater for the FF versus the DF BSFLM (P < 0.05). The apparent total tract digestibility of neutral detergent fiber and acid detergent fiber were greater for the FF versus the DF BSFLM (P ≤ 0.05). Both FF and DF BSFLM had high SID for most AA; however, FF BSFLM was a better source of net energy for growing pigs. Therefore, both FF and DF BSFLM could be used as protein alternatives in growing pig diets.

Objective: To address the challenges of physical sample retrieval from all locations along patients’ gastrointestinal (GI) tracts for studying of interactions between GI microbial communities (microbiomes) and host immune systems. Methods: We propose a novel tetherless, blindly controlled, magnetically actuated capsule for noninvasive sampling of GI microbiomes and liquid digesta. The mesoscale capsule, a soft mobile robot platform, is made from two permanent magnets encapsulated in a soft elastomer and actuated remotely by an external magnet. The capsule is controlled blindly using an external magnet to orient and activate the capsule. Following oral administration, capsules transit the GI tract and are activated at specified locations. The capsule is recovered via routine stool passage and collected samples are processed for downstream analyses (e.g. 16S rRNA surveys, metagenomics, metatranscriptomics and/or metabolomics). The localization of the capsule is estimated using the travelling time and the location of collected microbiomes will be confirmed by downstream analyses. A mathematical model of capsule activation is used to predict capsule activation and guide design optimization. Results: We demonstrate the ability of the capsule to collect samples, as well as maintain sample integrity in vitro, ex vivo, and with twelve capsules in in vivo swine models. Eleven capsules successfully collected digesta (in the range of 18 to 61 mg). Conclusion: The capsule successfully collected and sealed samples. Significance: This sampling apparatus offers a technological advance for the robust sampling of GI tract contents.

Weaning stress can negatively impact a pig’s performance; dietary supplementation with omega-3 polyunsaturated fatty acids (n-3 PUFA) reduces inflammatory stress and promotes nursery pig’s health and growth. Fish oil (FO) is a major source of n-3 PUFA; however, microalgae (AL) may provide an alternative source of n-3 PUFA. The aim of this study was to assess the health benefits of supplementing a plant protein-based nursery diet with 3.12% AL or 1.25% FO providing equal total n-3 PUFA compared to a control (CON) diet. Seventy-two pigs were fed experimental diets for three weeks (phases 1 and 2), followed by a common standard diet for three weeks (phase 3). Following phase 2, 8 pigs per treatment underwent a lipopolysaccharide (LPS) immune stress challenge to assess the acute-phase response and 8 pigs per treatment were vaccinated with novel antigens to assess acquired immunity. No significant differences in piglets’ growth were observed, despite decreased feed intake in FO piglets compared to AL piglets in phase 3. AL supplementation tended to reduce, and FO supplementation significantly reduced the LPS-induced fever response. The AL pigs had significantly reduced cortisol responses, increased cytokine concentrations, and increased chromogranin A concentrations compared to FO and CON pigs following LPS challenge. Results suggest that AL or FO supplementation in nursery diets differentially modulate the acute-phase response, possibly due to different n-3 PUFA profiles between the two ingredients.

One hundred and forty-four newly weaned pigs (6.74 ± 0.23 kg initial BW; 21 d of age) were used to determine the effect of partially replacing animal protein sources with black solider fly larvae meal (BSFLM) in nursery diets on growth performance, gut morphology, and immune response. After weaning, pigs were placed in 24 pens (six pigs per pen) and pens were randomly assigned to one of four dietary treatments (study d 0; n = 6), which were fed over three phases (phases I, II, and III were fed for 7, 14, and 21 d, respectively). Two nursery diets were formulated with 25% (LowFF) and 50% (HighFF) of the animal protein sources replaced by full fat BSFLM. Conventional nursery diets including animal protein sources without (CON−) and with antibiotics (220 mg Aureomycin per kg of complete feed; CON+) served as controls. On d 8, two pigs per pen were sacrificed to collect organ weights and for intestinal histomorphological measurements. On d 9 and d 23, two pigs per pen were vaccinated with the novel antigen ovalbumin (OVA). Blood samples were collected on d 9, d 23, and d 38 to assess concentrations of plasma haptoglobin and OVA-specific immunoglobulins G (IgG) and IgG1. On d 38, the same two pigs per pen underwent a dermal hypersensitivity test and skin-fold thickness was measured at 0, 6, 24, and 48 h postintradermal injection with OVA. Pigs fed the CON- had greater ADFI and lower G:F in phase II vs. those fed CON+ and HighFF diets (P < 0.05 and P < 0.05); intermediate ADFI was observed for pigs fed the LowFF diet. Overall in the nursery period, ADG (496 ± 13 g), ADFI (743 ± 23 g), G:F, and final BW (27.61 ± 0.66 kg) were not different among dietary treatments. There were no differences in organ weights, jejunal or ileal villus heights, or crypt depths among dietary treatments. There were no differences in OVA-specific IgG, IgG1, or plasma haptoglobin among dietary treatments at any of the blood sampling times. Although not different, pigs fed the LowFF, HighFF, and CON+ diets had respectively 2.0×, 1.7×, and 1.4× greater dermal hypersensitivity response to OVA versus those fed CON−. Both inclusion levels of BSFLM in nursery diets supported growth performance, gut morphology, and indices of immune function not different from the CON+, which suggest that full fat BSFLM can replace at least 50% of animal protein sources in nursery diets of pigs without any deleterious effects on pig growth.

A total of 240 newly weaned pigs (5.25 ± 0.15 kg BW) were used to determine the dietary omega-6-to-omega-3 (ω-6:ω-3) fatty acid ratio that optimized growth performance and immune responses when fed corn and soybean meal-based diets with low protein quality. Pigs were randomly assigned to 1 of 5 dietary treatments (n=6 pens/treatment; d 0 of study): [1] positive control (High; included animal proteins and 5% corn oil), [2] negative control (Low0; corn and soybean meal-based and 5% corn oil), or 1 of 3 Low diets with increasing supplementation of fish oil to replace corn oil: [3] 1.25% (Low1.25), [4] 2.5% (Low2.5), [5] 5 % (Low5) to achieve 5:1, 3:1 and 1:1 ω-6:ω-3 ratios, respectively. Pigs were fed dietary treatments in two phases for 7 and 14 d, respectively, followed by a common phase III diet for 21 d. On d 6 and 20, 12 pigs per treatment were immune sensitized with 0.5 mg ovalbumin (OVA) and 0.5 mg Quil A adjuvant in 1 ml saline. The dermal hypersensitivity response (DHR) was evaluated on d 40 in these same pigs, using intradermal injection of OVA; changes in skin-fold thickness were measured. On d 21, 4 pigs per pen were immune challenged with LPS (30 mg Escherichia coli LPS/kg BW) or saline (n=12); rectal temperature was monitored over 3 hrs. During phase I only, ADG, ADFI, and G:F were greater for pigs fed the High diet versus those fed the Low diet (P < 0.05), and increased with increasing fish oil supplementation up to 2.5% (Low2.5), but decreased for pigs fed the Low5 diet (quadratic; P < 0.05, P = 0.086, and P < 0.05 for ADG, ADFI, and G:F, respectively). On d 21, LPS increased rectal temperature (vs saline at 1, 2, and 3 hr post-challenge; P < 0.001); fish oil supplementation reduced rectal temperature 2 hr post-challenge in the Low-fed pigs (linear; P < 0.05). On d 22, serum haptoglobin was greatest for pigs fed Low0 and decreased with increasing fish oil supplementation (linear; P < 0.05). Immunization with OVA induced a serum anti-OVA IgG response, which was reduced on d 34 among pigs fed Low diets with increasing fish oil supplementation (linear; P = 0.050). On d 40, and 6 hr after intra-dermal injection of OVA, the DHR was least for pigs fed the Low2.5 diet (P < 0.05). Inclusion of 2.5% fish oil (3:1, ω-6:ω-3) optimized growth performance during the early nursery phase when pigs were most sensitive to diets with low protein quality; the ideal ω-6-to-ω-3 fatty acid ratio may differ when using immune responses as the major outcome.

Thirty five barrows (initial body weight [BW]: 15.1 ± 1.0 kg) were used to determine the effect of partially replacing Gly + Ser with Thr in reduced crude protein (CP) diets on growth performance, protein deposition in carcass and viscera, and skin collagen abundance during the late nursery phase to 25 kg BW. Pigs were individually fed one of five iso-nitrogenous diets (n = 7) for 21 d. The basal diet met estimated essential amino acids (AA) requirements by using all essential AA plus Gly and Ser in free form (CON; 12.1% CP; as-fed, analyzed contents). The remaining four diets were formulated by reducing total Gly and Ser concentrations to 60% or 20% of the CON diet. The N removed with Gly and Ser was replaced with either crystalline Thr or Glu. Total analyzed Thr made up either 1.59% (T1; 12.5% CP) or 2.34% (T2; 12.2% CP) of the Thr-supplemented diets, and total analyzed Glu made up either 3.47% (G1; 12.7% CP) or 4.64% (G2; 12.9% CP) of the Glu-supplemented diets. Pigs were slaughtered on day 21 to determine body composition and skin collagen abundance via bright field microscopy. Overall, average daily gain (ADG) and G:F and final carcass weights were greater for pigs fed diets supplemented with Glu (G1 + G2) vs. those fed diets supplemented with Thr (T1 + T2; P < 0.05, P = 0.060, and P = 0.050 for ADG, G:F, and final carcass weight, respectively); intermediate values were observed for CON. Nitrogen retention in carcass plus viscera and the AA profile of deposited protein in the carcass were not influenced by dietary treatment. Pigs fed the T2 and G2 diets had greater retention of Thr (vs. CON and G2) and Glu (vs. CON and T2) in the viscera protein, respectively (P < 0.05). The apparent utilization efficiency of standardized ileal digestible Thr for protein deposition in carcass plus viscera was less for pigs fed T2 (15.1%) vs. those fed CON (56.7%) or G2 (58.6% ± 2.9%) diets (P < 0.001). Only pigs fed T1 had skin collagen abundance not different from CON; pigs fed G1, G2, and T2 had reduced skin collagen abundance compared with CON and T1 (P < 0.01). Using Glu as an N source when Gly and Ser were reduced to 60% and 20% of CON in reduced CP diets maintained ADG for pigs between 15 and 25 kg BW, whereas supplying Thr as a N source reduced ADG and carcass weight. When dietary Gly and Ser were supplied at 60% of CON, only Thr supplementation rescued skin collagen abundance. Therefore, supplemental Thr at excess levels is not sufficient to replace N from Gly and Ser in reduced CP diets fed to late nursery pigs, despite supporting skin collagen abundance as a secondary indicator of Gly status.