The effect of a novel consensus bacterial 6-phytase variant (PhyG) on total tract digestibility (ATTD) of minerals and bone ash was evaluated in pigs fed diets containing medium and high solubility limestone (MSL and HSL, 69.6 and 91.7% solubility, respectively, at 5 min, pH 3.0) in a randomized complete block design. For each limestone, 8 diets were formulated: an inorganic phosphate-free negative control (NC) based on wheat, corn, soybean-meal, canola-meal and rice-barn [0.18% standardized total tract digestible (STTD) P and 0.59% Ca]; the NC supplemented with 250, 500, 1,000 or 2,000 FTU/kg of PhyG, and; the NC with added monocalcium phosphate (MCP) and limestone to produce 3 positive controls (0.33, 0.27 and 0.21% STTD P, and 0.75, 0.70 and 0.64% Ca, respectively; PC1, PC2, PC3). In total, 128 pigs (12.8 ± 1.33 kg, 8 pigs/treatment, housed individually) were adapted for 16 d followed by 4 d of fecal collection. Femurs were collected from euthanized pigs on d 21. Data were analyzed by one-way ANOVA with means separation by Tukey’s test, and by factorial analysis (2 x 4: 2 levels of limestone solubility, 4 STTD P levels, and 2 × 5: 2 levels of limestone solubility, 5 PhyG dose levels). Phytase dose-response was analyzed by curve fitting. A consistent negative effect of HSL on ATTD P and Ca was observed in control diets (P < 0.001). Across phytase-supplemented diets, HSL reduced (P < 0.05) ATTD Ca and P (% and g/kg) compared with MSL. Across limestones, increasing phytase dose level increased (P < 0.05) ATTD P exponentially. Limestone solubility had no effect on bone ash, but PhyG linearly increased (P < 0.05) bone ash; 500 FTU/kg or higher maintained bone ash (g/femur) equivalent to PC1. In conclusion, ATTD P and Ca were reduced by a high compared with a medium soluble limestone, but the novel phytase improved ATTD P and Ca independent of limestone solubility.

The capacity of a novel consensus bacterial 6-phytase variant (PhyG) to entirely replace dietary inorganic phosphorus (Pi) source in grower pigs fed diets with reduction of calcium (Ca), net energy (NE) and digestible amino acids (AA) was evaluated, using growth performance and apparent total tract digestibility (ATTD) of nutrients as outcome measures. A total of 352 mixed-sex pigs (initial BW 23.4 kg) were randomized to 4 treatments, 8 pigs/pen and 11 pens/treatment. Diets were corn-soybean meal-based and formulated by phase (grower 1, 25 to 50 and grower 2, 50 to 75 kg BW). The positive control diet (PC) provided adequate nutrients and a negative control diet (NC) was formulated without Pi (1.2 g/kg ATTD P) and reduced in Ca (-0.12 to -0.13 percentage points), NE (-32 kcal/kg) and digestible essential AA (-0.004 to -0.026 percentage points) vs. PC. Two further treatments comprised the NC plus 500 or 1,000 FTU/kg of PhyG. Data were analyzed by ANOVA, mean contrasts and orthogonal polynomial regression. Nutrient reductions in the NC reduced (P < 0.05) average daily gain (ADG) during grower 1 and overall (73 to 136 days of age), increased (P < 0.05) feed conversion ratio (FCR) during grower 1 and overall and tended to reduce (P < 0.1) average daily feed intake (ADFI) during grower 2 and overall, vs. PC. Phytase supplementation improved (P < 0.05) FCR during grower 1, ADG during grower 2 and overall, ATTD of DM and P, and tended to improve DE (P = 0.053) in a linear dose-dependent manner. PhyG at 1,000 FTU/kg resulted in growth performance (all measures, all phases) equivalent to PC. The findings demonstrate that PhyG at 1,000 FTU/kg totally replaced Pi in complex grower pig diets containing industrial co-products, compensated a full nutrient matrix reduction and maintained performance.

Porcine reproductive and respiratory syndrome virus (PRRSV) remains a major challenge to swine production worldwide. Current vaccines have limited efficacy against genetically diverse PRRSV strains. Therefore, strategies with alternative modes of action—such as antiviral approaches that target conserved virus–host interactions, including viral attachment and entry, rather than relying solely on adaptive immune responses—are needed. We first evaluated the in vitro effect of griffithsin (GRFT), a high-mannose-binding lectin, in the monkey kidney cell line MARC-145. Cells were pre-treated with GRFT (50–200 µg/mL) prior to PRRSV infection, after which cell morphology and viral RNA replication (measured by RT-qPCR) were assessed. Pre-treatment with 100–200 µg/mL GRFT, followed by PRRSV inoculation at a multiplicity of infection of 1 or 10, reduced viral replication in MARC145 cells in a dose-dependent manner, achieving almost 100% inhibition of ORF5 and ORF7 RNA compared with untreated controls (p < 0.0001). We next investigated the in vivo effects of intranasal GRFT administration (7.5 or 15 mg/day) in pigs (n = 56). Pigs treated with 15 mg/day GRFT exhibited significantly reduced (p < 0.05) viremia 2, 4 and 7 days post-challenge, compared with untreated, challenged, and controls (log₁₀ 8.1 ± 0.2 vs. 9.0 ± 0.25, 8.2 ± 0.1 vs. 9.1 ± 0.2, and 8.9 ± 0.2 vs. 9.3 ± 0.2, respectively), along with earlier resolution of fever and a trend toward increased average daily gain over 42 days (p < 0.1). These findings are the first report of GRFT efficacy in pigs and support its potential as an antiviral strategy against PRRSV, alongside existing interventions.

This experiment tested the hypothesis that supplementation of a nutrient- and energy-reduced mixed-cereal diet with phytase, xylanase and β-glucanase, over an entire wean-to-finish growth cycle, would result in growth performance outcomes that were not different from those achieved by pigs fed an unsupplemented, nutritionally-adequate diet. A total of 192 weaned pigs [DanBred × Pi, initial body weight (BW) 7.2 ± 0.4 kg] were assigned to 48 floor pens [4 pigs/pen (2 male, 2 female), 12 pens/treatment], in a completely randomized design. Diets included: 1) a nutritionally adequate wheat, corn and barley-based positive control (PC); 2) a negative control (NC) based on the PC but without added inorganic P, reduced in Ca, net energy (NE), digestible amino acids (AA) and Na, supplemented with PhyG at 1,000, 1,000, 750, 500 and 500 FTU/kg in starter I (7 to 11 kg BW), starter II (11 to 25 kg BW), grower I (25 to 55 kg BW), grower II (55 to 85 kg BW) and finisher (85 to 115 kg BW) phases, respectively (NC1 + PhyG low); 3) NC1 further reduced in Ca, digestible AA and NE, (by ≤ 0.03 percentage points, ≤ 0.01 percentage points and ≤ 9 kcal/kg, respectively) supplemented with PhyG at 2,000, 2,000, 1,000, 750 and 750 FTU/kg per phase (NC2 + PhyG high), and; 4) as 2) but further reduced in NE and digestible AA (by 26 to 33 kcal/kg and ≤ 0.01 percentage points, respectively), supplemented with 2,440 XU/kg xylanase and 304 U/kg β-glucanase (NC3 + PhyG low + XB). For the overall period, growth performance (all measures) was maintained in the enzyme-supplemented treatments to a level not different from the PC, whereas in starter II and grower I, BW was increased (+ 1.82 and + 5.11 kg/pig, respectively; P < 0.05) and gain:feed was increased (P < 0.05) in NC3 + PhyG low + XB, compared with the PC. Total estimated feed costs per kilogram BW gain (BWG) were lower (P < 0.05) in NC3 + PhyG low + XB (-0.05 € or 7.3%) and the carbon footprint of production was reduced in NC2 + PhyG high and NC3 + PhyG low + XB compared with the PC (by 128 and 145 g CO2 equivalents per kilogram of BWG, respectively, equivalent to reductions of 6.0% and 6.8%; P < 0.05). These results confirm the appropriateness of the applied energy and nutrient reductions for PhyG and PhyG with xylanase–β-glucanase in a mixed-cereal diet from wean to finish and highlight a potential feed cost saving and environmental sustainability benefit of the application.

Data from 8 datasets generated from 5 independent experiments that determined the effects of a consensus bacterial 6-phytase variant (PhyG) on apparent ileal digestibility (AID) of amino acids (AA) in growing pigs (~21 to 45 kg body weight) were combined and modeled to test the hypothesis that the phytase results in significant improvements in ileal AA digestibility. The aim was to generate accurate and robust dose-related predictions of the digestible AA contributions of the phytase. The 5 experiments were conducted in Spain, Australia, USA, and Brazil and incorporated variation in diet composition (ingredient composition, phytate-phosphorus (PP) content, limestone solubility), diet form, animal breed and sex. A total of 325 datapoints (observations) were analyzed. First, the relationship between the percentage AID of AA and log-transformed phytase dose (range 0 to 4,000 phytase units (FTU)/kg, analyzed values) was modeled by log-linear regression across all datasets without adjustment for variation in the response to the negative control (NC) diet. The model predicted that the mean AID of total AA in the NC diets was 68.6% (range 43.3% [Cys] to 81.7% [Arg]). This was increased linearly by PhyG supplementation (P < 0.05), by 3.7 percentage units when dosed at 1,000 FTU/kg and by 4.5 percentage units at 4,000 FTU/kg. Second, the percentage unit change in the AID of AA at each phytase dose from baseline (NC without added phytase) was calculated separately for each dataset and the data then combined and modeled together by log-linear regression, against analyzed and log-transformed phytase dose. By this analysis, increases were evident for the AID of all individual (and total) AA. Increases (vs. baseline) at 1,000 and 2,000 FTU/kg were greatest for Trp (+ 6.1 and + 6.8 percentage units), Thr (+ 3.4 and + 3.8 percentage units after correction for synthetic Thr), Gly (+ 7.5 and + 8.3 percentage units) and Cys (+ 5.6 and + 6.2 percentage units). In conclusion, combined data from 5 separate experiments indicate that the bacterial phytase-6 variant will improve ileal digestibility of AA if included in diets fed to growing pigs. The data will allow diet-specific AA matrix recommendations to be made in commercial feed formulations containing PhyG.

Reducing the environmental and climatic impact while maintaining high growth performance is an urgent challenge in pig production. Limiting methane emissio