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.

Two studies were conducted to determine whether soybean meal (SBM) use in nursery pig diets can be increased by superdosing with phytase. In Exp. 1, 2,550 pigs (BW of 5.54 ± 0.09 kg) were used to evaluate the optimal level of phytase in low- or high-SBM diets. Two SBM levels (low and high) and 4 phytase doses (0, 1,250, 2,500, and 3,750 phytase units [FTU]/kg) were combined to create 8 dietary treatments in a 2 × 4 factorial arrangement. Pigs were fed a 3-phase feeding program, with each period being 10, 10, and 22 d, respectively. Inclusion of low and high SBM was 15.0 and 25.0%, respectively, for Phase 1; 19.0 and 29.0%, respectively, for Phase 2; and 32.5% for the common Phase 3 diet. Pigs fed diets with high SBM had improved G:F for Phase 1 and 2 and overall ( < 0.01) compared with low-SBM diets. Phytase quadratically improved G:F during Phase 3 and overall ( < 0.05), with the optimum phytase dose being 2,500 FTU/kg. High-SBM diets tended ( = 0.09) to decrease stool firmness (determined daily from d 1 to 10) only on d 2. In Exp. 2, 2,112 pigs (BW of 5.99 ± 0.10 kg) were used to evaluate the impact of high levels of SBM and phytase on performance, stool firmness, mortality, and morbidity in weaned pigs originating from a porcine reproductive and respiratory syndrome (PRRS) virus-positive sow farm. Pigs were fed a 3-phase feeding program as in Exp. 1. Three levels of SBM (low, medium, or high) and 2 phytase levels (600 or 2,600 FTU) were combined to create 6 dietary treatments in a 3 × 2 factorial arrangement. Inclusion of SBM was 15.0, 22.5, and 30.0% for Phase 1 and 20.0, 27.5, and 35.0% for Phase 2 for low, medium, and high SBM, respectively, and 29.0% for the common Phase 3 diet. Inclusion of SBM did not affect growth performance. The percentage of pigs removed for medical treatment linearly declined with increasing SBM levels ( = 0.04). High-SBM diets tended ( < 0.10) to decrease stool firmness during d 4 and 5 and high phytase tended ( < 0.10) to improve stool firmness on d 2 and 4. Analyzed PRRS titers in saliva samples collected on d 20 and 42 confirmed the PRRS status of the pigs; however, viral load was not impacted by dietary treatments ( ≥ 0.11). Results indicate that SBM levels in early nursery diets can be increased without decreasing growth performance and may be favorable in pigs originating from PRRS-positive sow farms by reducing costs of medical treatments. Supplementation of phytase at superdose levels can improve growth performance independently from the level of SBM in the diet.

A total of 2,156 weaned pigs (6.75 ± 0.11 kg BW) were used in a 42-d study to evaluate whether improvements in growth performance associated with super-dosing phytase can be explained by the complete dephosphorylation of phytate and liberation of inositol. Two phytase doses (0 and 2,500 FTU/kg) and 3 inositol concentrations (0%, 0.15%, and 0.30%) were combined to create 6 dietary treatments in a 2 × 3 factorial arrangement. Pigs were fed a 3-phase feeding program, with periods being 10, 10, and 22 d, respectively. Blood samples were collected on days 0, 21, and 42 from a subset of 48 pigs to analyze mineral and myo-inositol concentrations. During Phase 1, super-dosing phytase tended to improve ADG compared with pigs fed diets without phytase (P = 0.09). Increasing concentrations of inositol improved the efficiency of gain in pigs fed diets without phytase (1,022.1, 1,040.9, and 1,089.2 g/kg), but not diets with phytase (1,102.2, 1,087.2, and 1,076.2 g/kg), and this improvement was equivalent to that observed with super-dosing phytase in the absence of inositol (interaction, P = 0.015). During Phase 2, super-dosing phytase improved ADG (P = 0.001), resulting in heavier BW (P = 0.007). During Phase 3 and overall, inositol supplementation increased ADG and ADFI in a quadratic manner (P < 0.10), with the highest ADG and ADFI observed for pigs fed 0.15% of inositol. Super-dosing phytase increased serum Zn on day 21, but not on day 42 (interaction, P = 0.008), increased serum Cu (P = 0.01), but decreased serum Fe (P = 0.02). Plasma myo-inositol increased linearly from 66.9 to 97.1 and 113.2 nmol/mL with increasing inositol (P < 0.001). When plasma myo-inositol was analyzed within the subgroup of pigs fed diets without added inositol, super-dosing phytase increased plasma myo-inositol from 57.81 to 76.05 nmol/mL (0 and 2,500 FTU/kg, respectively; P = 0.05). Results demonstrate that exogenous inositol improved efficiency of gain in weaned pigs to the same level as that observed with super-dosing phytase, but this occurred only during the first 10 d of the nursery period. This suggests that the improvement in efficiency of growth when applying super-dosing phytase could be linked, in part, to complete dephosphorylation of phytate and liberation of myo-inositol, and that myo-inositol had a greater metabolic impact in piglets immediately after weaning. Consequently, myo-inositol may be a conditionally essential nutrient for young pigs during weaning stress, but further research is needed to prove this hypothesis.

The objective of this study was to investigate the impact of lipid peroxidation in a dose-dependent manner on growth, health, and oxidative stress status of nursery pigs. A total of 2,200 weaned pigs (5.95 ± 0.20 kg BW) were housed in 100 pens (22 pigs per pen) in a randomized complete block design based on initial BW and sex. Pigs were randomly assigned within blocks to 5 dietary treatments, consisting of a corn–soybean meal-based diet supplemented with 5% of either control corn oil (iodine value = 118, FFA = 0.06%, anisidine value = 3, peroxide value = 3 mEq/kg oil) or peroxidized corn oil (iodine value = 120, FFA = 0.35%, anisidine value = 30, peroxide value = 163 mEq/kg oil). These 2 diets were blended to obtain 5 levels of peroxidation with final treatments designated as 0 (diet with 5% control oil), 25%, 50%, 75%, and 100% (diet with peroxidized corn oil) peroxidation. Diets were fed ad libitum for 43 d. Blood samples were collected on d 33 from 20 pigs per treatment to determine serum oxidative stress markers and vitamin E concentrations and again on d 43 (14 d after vaccination) to determine immune response to porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae (Mhyo). Gain:feed ratio decreased linearly (P = 0.023) with increasing peroxidation, but pen ADG and ADFI were not affected. Number of pigs removed for medical treatment, total number medically treated, pigs culled for low end weight, and mortality increased, and full-value pigs linearly decreased (P < 0.04) with increasing peroxidation. Consequently, total pen gain (weight of viable pigs that remained in test pens at the end of the study minus weight of pigs placed) decreased linearly (P < 0.01) with increasing peroxidation. Antibody titers to Mhyo and PCV2 increased postvaccination (P < 0.001), but did not differ due to dietary treatment. Serum concentrations of malondialdehyde, 8-hydroxy-2′-deoxyguanosine, and protein carbonyl were not affected by peroxidation. Total antioxidant capacity and serum vitamin E concentrations decreased (P = 0.01) linearly with increasing peroxidation. Data show a dose-dependent negative impact of lipid peroxidation on pig productivity when determined under field population conditions, being primarily manifested by increased mortality, number of pigs medically treated, and number of culled pigs (≤13.6 kg BW). Results underscore the importance of proper assessment of lipid peroxidation as part of quality control to prevent oxidative stress and performance losses in weaned pigs.

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