Two experiments were conducted to determine the effect of feeding supplemental -Arg during late pregnancy on piglet birth weight and preweaning performance. In Exp. 1, 97 gilts and sows were allotted (gestation d 93) to receive a control diet (CON; 19.8 g standardized ileal digestible [SID] Arg/d) or the CON + 1.0% -Arg (ARG; 46.6 g SID Arg/d). Gilts and sows were weighed on gestation d 93 and 110, 48 h after farrowing, and at weaning. Data, including number born alive, number weaned, individual birth and weaning weight, and placenta weight, were recorded. Blood samples were collected on d 93 and 110 and analyzed for plasma IGF-1, insulin, and blood urea nitrogen concentration. In a second experiment, 383 sows in a commercial research farm were allotted to receive CON or ARG. An -Arg premix was provided daily by top dress beginning at gestation d 81 (±0.1 d) and fed for an average of 35 d (±0.2 d). Sows received 2.73 kg feed/d with CON sows provided 17 g SID Arg/d and ARG sows receiving a total of 44 g SID Arg/d. Litter birth weight was recorded and average birth weight was computed. In a subset of 82 sows, individual birth weights were recorded. In Exp. 1, there was a tendency for greater late pregnancy maternal BW gain ( = 0.06) in ARG compared with CON. A tendency for a parity × treatment interaction was observed for late pregnancy BW gain, with first litter sows fed ARG gaining the most, gilts fed ARG intermediate, and all other treatments gaining the least ( = 0.10). No differences between treatment groups were observed for maternal plasma IGF-1, insulin, and urea nitrogen and in progeny performance to weaning ( > 0.28). In Exp. 2, piglet birth weight was more effectively tested because of the large number of multiparous sows involved. There was a tendency for individual birth weight to decline in ARG compared with CON ( < 0.08), but birth weight distribution between <0.80 and >2.8 kg was similar. No other differences were observed ( > 0.18). In conclusion, late pregnancy supplementation with -Arg had no effect on number of pigs born alive, piglet birth weight, or lactation performance.

Feed additives have been suggested to improve animal growth performance through modulating the gut microbiota. The hypothesis of this study was that the combination of two organic acids would exert synergistic effects on the growth performance and gut microbiota of weaning pigs. To test this hypothesis, we followed 398 weaning pigs from two university experiment stations (University of Illinois at Urbana-Champaign (UIUC) and University of Arkansas (UA)) to determine the effects of increasing levels (0%, 0.035%, 0.070%, and 0.105%) of sodium butyrate combined with 0.5% benzoic acid on the growth performance of nursery pigs. At the UA, an additional negative control diet was included and the gut microbiota analysis was carried out. At both universities, increasing levels of sodium butyrate in a diet containing 0.5% benzoic acid improved growth performance, which reached a plateau in the pigs fed 0.035% (SBA0.035) or 0.070% (SBA0.070) butyrate. Gut microbiota analysis revealed that pigs fed the SBA0.035 diet had more diverse microbiota and contained more potentially beneficial bacteria such as Oscillospira, Blautia, and Turicibacter and reduced levels of Veillonella and Sarcina. Results of the present study indicated that the inclusion of sodium butyrate at moderate levels in a diet containing 0.5% benzoic acid improved growth performance of weaning pigs and established potential health benefits on gut microbiota.

Effect of timing of xylanase supplementation to weanling pigs and its effect on growth performance, nutrient digestibility, and fecal microbiota was investigated. A total of 128 weanling pigs [(Hampshire × Duroc) × (Yorkshire × Landrace); 6.2 ± 0.6 kg body weight (BW); weaning age: 21 d] were assigned to four treatments, with eight replicate pens and four pigs per pen. Treatments were a combination of two dietary treatments (without or with xylanase) in two periods; (period 1, days 0–14) and period 2 (days 14–42): xylanase–xylanase, xylanase–control, control–xylanase, and control–control. Fecal microbiota diversity and apparent total tract digestibility (ATTD) were determined. From days 0–14, pigs had lower (P < 0.01) BW, average daily gain (ADG), and feed efficiency when xylanase was included in the diets. The final BW (P < 0.05) and overall ADG (P < 0.02) at day 42 were greater when xylanase was supplemented from day 14 compared with supplementation from day 0. The apparent ileal digestibility and ATTD of dry matter, gross energy, nitrogen, and phosphorus were increased (P < 0.05) by xylanase. Xylanase significantly decreased (P < 0.05) the relative abundance of Veillonella spp. and tended (P = 0.08) to decrease the relative abundance of Megasphaera spp. in period 2 compared with the non-supplemented group.

A 42-d commercial nursery study was conducted utilizing 1,296 pigs (DNA genetics, BW: 5.27 ± 0.05 kg; 21-d of age) that evaluated the efficacy of replacing animal protein products while also reducing SID Lys in nursery pig diets with a bioactive peptide-based feed additive program on growth performance, efficiency, health and well-being, and profitability. The dietary treatments were applied over 3 phases (PH) and were fed based on a feed budget: PH1: 2.27 kg/pig [Positive Control (PC): 1.46% SID Lys; 3,415 kcal/kg ME]; PH2: 4.54 kg/pig (PC: 1.42% SID Lys; 3,395 kcal/kg ME); and PH3: 15.88 kg/pig (1.26% SID Lys; 3,395 kcal/kg ME). The four dietary treatments were: 1) PC: complex diet in PH1-2 and standard diet in PH3; 2) negative control (NC): diet in PH1-2 devoid of fishmeal and spray-dried plasma and -0.10% SID Lys compared to the PC and PH3 the same as the PC; 3) PEP1 in PH1-2 was the NC diets plus Peptiva® Maximo (Vitech Bio-Chem Corp., Orange, CA) fed at 0.25% and in PH3 the PC + Peptiva® Optimo fed at 0.1%; 4) PEP2 in PH1-2 was the NC diets plus Peptiva® Maximo fed at 0.50% and in PH3 the PC plus Peptiva® Optimo fed at 0.2%. Pen weights of pigs and pen feed consumption were evaluated in 2-wk increments and overall. Additionally, animal health and well-being and economics were evaluated for the entire nursery program. Overall, pigs fed the PEP1 diets had a better FCR (with or without mortality adjustments) than either control group, while the PEP2 group was intermediate. These results indicate that highly digestible proteins, such as fish meal and spray-dried plasma, can be removed from early nursery diets while supplementing with bioactive-peptide feed additive strategy to optimize performance and economics of production.

A subset of 720 weaned pigs (6.44 ± 0.1 kg, PIC genetics, approximately 21-d of age) were used in a 42-d trial with a 2x3 factorial design evaluating the effects of adding organic acid (OA) blends [factor 1 = no organic acid (NO), Acid Pak 1 (AP1), Acid Pak 2 (AP2)] to diets with or without higher levels of Zn or Cu [factor 2 = +/-PZC] on pig performance. Pigs were allotted 10 pigs/pen to 12 weight blocks and randomly assigned the six dietary treatments. The +PZC diets contained 3000 ppm Zn (d 0-7), 2000 ppm Zn (d 8-21), and 250 ppm Cu (d 21-42) and -PZC diets contained 95 ppm Zn and 20 ppm Cu (d 0-42). The AP1 and AP2 diets used 0.9% of 2 acid premixes (d 0-21), and 0.45% of the premixes (day 22-42). AP1 provided 0.5% benzoic acid, 0.07% sodium butyrate, and 0.025% phosphoric acid (day 0-21) and half those levels (day 22-42). AP2 included the same acids as AP1 but at half the rate and combined with 7 other organic acids and carvacrol. From d 0-21, ADG, ADFI, and G:F were improved (P&lt; 0.01) by +PZC compared to -PZC and by AP1 or AP2 compared to NO (P&lt; 0.02). Overall (d 0-42), ADG and G:F were improved (P&lt; 0.01) by +PZC compared to -PZC and by AP1 or AP2 compared to NO (P&lt; .010). Data from this trial indicate that performance was improved by the addition of both OA and PZC. However, pigs fed OA and -PZC performed similarly to those fed NO and +PZC in the post-weaning period. In summary, regardless of the acid combination, organic acid supplementation has the potential to improve growth performance in weaned pigs.