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This study investigated the interactive effects of copper (Cu) sources and superdose phytase on growth performance, nutrient digestibility and tissue mineral concentrations in nursery pigs. A total of 288 weaning barrows (PIC 337 × 1050, Hendersonville, TN; BW = 6.06 ± 0.99 kg), blocked by BW, were randomly allotted to 1 of 6 dietary treatments, with 12 pens/treatments and 4 pigs/pen. Six dietary treatments were arranged in 3 × 2 factorial design, with 3 Cu sources [125 ppm Cu from copper sulfate (CuSO4), tribasic copper chloride (TBCC) or copper methionine hydroxy analogue chelate (Cu-MHAC, MINTREX® Cu, Novus International, Inc.), respectively] and 2 phytase levels [0 or 1500 FTU/kg from phytase PHYTAVERSE® G10 (Novus International, Inc.)]. There was an interaction (P = 0.05) between Cu sources and superdose phytase on ADG during d 0–41, with the improvement by superdose phytase being 25.84, 33.96 and 40.85% when the Cu sources were CuSO4, TBCC and Cu-MHAC, respectively. Superdose phytase significantly (P < 0.01) reduced F:G during d 0 to 41. Cu-MHAC led to greater ATTD of neutral and acid detergent fiber (NDF, ADF, respectively; P = 0.01) than CuSO4 and TBCC, respectively. Cu-MHAC led to greater (P = 0.03) ATTD of P than CuSO4, with TBCC intermediate. There was no interaction (P > 0.10) between Cu sources and superdose phytase in terms of nutrient digestibility and tissue mineral concentrations. Cu source did not (P > 0.10) affect tissue mineral concentrations; however, superdose phytase increased (P ≤ 0.05) bone Ca and P concentrations. In conclusion, Cu-MHAC may improve the efficacy of superdose phytase in terms of growth performance, most likely by improving phytate P hydrolysis and therefore providing more P for absorption. Superdose phytase is effective in improving growth performance of nursery pigs, mainly driven by increased Ca and P absorption and utilization.

This study investigated the interactive effects of zinc (Zn) and copper (Cu) sources and phytase on growth performance, oxidative status, mineral digestibility, tissue mineral concentrations, and gut morphology in nursery pigs. A total of 288 weaning barrows [body weight (BW) = 5.71 ± 0.81 kg], blocked by initial BW, were randomly allotted to one of eight dietary treatments, with nine pens per treatment and four pigs per pen. The eight dietary treatments were arranged in 2 × 2 × 2 factorial design, with two Zn sources [2,000, 2,000, and 100 mg/kg Zn from zinc oxide (ZnO) during phase 1 (days 1–14) and phase 2 (days 15–28), and phase 3 (days 29–42), respectively; 100 mg/kg Zn from zinc methionine hydroxy analogue chelate (Zn-MHAC) from phases 1 to 3], two Cu sources [150, 80, and 80 mg/kg Cu from copper sulfate (CuSO4) or copper methionine hydroxy analogue chelate (Cu-MHAC) during phases 1–3, respectively], and two phytase inclusion levels (0 or 500 FTU/kg). Results showed that ZnO supplementation at 2,000 mg/kg Zn significantly increased average daily feed intake (ADFI; P = 0.01) and average daily gain (ADG; P = 0.03) during phase 1 compared to Zn-MHAC group; however, Zn-MHAC supplementation tended (P = 0.06) to improve gain to feed ratio (G:F) during phase 2 compared to ZnO group. There were no differences (P > 0.10) between ZnO and Zn-MHAC groups in terms of ADG, ADFI, and G:F during the entire nursery period. Compared with CuSO4, Cu-MHAC tended to increase ADG (P = 0.07) and G:F (P = 0.08) during the entire nursery period. Phytase supplementation significantly increased ADG (P < 0.01), ADFI (P < 0.01), and G:F (P < 0.01) during the entire nursery period compared with no phytase supplementation. There was a significant interaction (P < 0.01) between Zn source and phytase on standardized total tract digestibility (STTD) of phosphorus (P), whereas there was no interaction (P = 0.21) between Cu sources and phytase on STTD of P. However, there was a significant interaction between Cu sources and phytase on calcium (Ca; P = 0.02) and P (P = 0.03) concentrations in metacarpal bones and G:F in phase 2 (P = 0.09). Furthermore, pigs fed diets containing Zn-MHAC tended to have lower ileum villus width (P = 0.07), compared with those fed diets containing ZnO, and pigs fed diets containing Cu-MHAC tended to have lower plasma malondialdehyde concentration (P = 0.10) compared with those fed diets containing CuSO4. In conclusion, under the conditions of the current study, ZnO supplementation at 2,000 mg/kg Zn was only effective in the first 2 wk postweaning, whereas Zn-MHAC supplementation at 100 mg/kg Zn could achieve better feed efficiency during phase 2 compared to pharmacological levels of ZnO, therefore, leading to no difference of growth performance in the entire nursery period. Low levels of Zn-MHAC may improve phytase efficacy on degrading phytate P compared to pharmacological levels of ZnO. Cu-MHAC may be more effective to promote growth compared to CuSO4, which may be partially driven by reduced oxidative stress. Results also indicated that Cu-MHAC might exert a synergistic effect with phytase on improving feed efficiency and bone mineralization.

The present study aimed to determine the optimal ratio of standardized ileal digestible (SID) total sulfur amino acid (TSAA) to Lys for growth performance in 5 to 22 kg pigs under antibiotic-free regime. Experimental diets were formulated to ensure that lysine was the second limiting AA throughout the experiments. A total of 990 weaning piglets (PIC 337 × 1050, Hendersonville, TN; 5.08 ± 0.86 kg), blocked by initial BW and gender, were randomly allotted to 1 of 5 dietary treatments, with 9 pens per treatment and 22 piglets per pen. Dietary treatments consisted of SID TSAA to Lys ratios of 51%, 58%, 65%, 72% and 79%, with 1.31%, 1.28% and 1.20% SID Lys in phases 1, 2 and 3, respectively. The source of TSAA used in this study was the dry calcium salt of D, L-2-hydroxy-4-(methylthio)butanoic acid (84% Met, MHA®, Novus International, Inc., St. Charles, MO). Data was analyzed using general linear mixed models accounting for heterogeneous residual variances. Competing heteroskedastic models included broken-line linear (BLL), broken-line quadratic (BLQ), and quadratic polynomial (QP). For each response, the best-fitting model was selected using Bayesian information criterion. Results showed that increasing ratios of SID TSAA to Lys linearly (P = 0.01) increased ADG during the entire nursery period. Increasing SID TSAA to Lys ratios tended to increase (P = 0.09) overall ADFI in a quadratic manner. The best-fitting model for overall ADG is BLL in which the maximum ADG was estimated at 60% SID TSAA to Lys ratio, with 95% confidence interval (CI) between 55% and 65%. In conclusion, the optimal ratio of SID TSAA to Lys was 60% for maximum ADG. These results indicate that the NRC (2012) recommendation may underestimate the SID TSAA to Lys requirement for nursery pigs raised under antibiotic-free regime.

Lameness in gilts and sows has an economic impact on pig production and is a major welfare concern. The objective of the present project was to evaluate and quantify lameness in pigs. The following methods were compared to visual gait scoring: force-plate, hoof hardness and hoof lesions. Eight barrows and seven gilts (114 ± 15 kg) were selected using visual gait scoring (0-4, 4 most severe). From this group there were 4-0’s, 4-1’s, 5-2’s, and 2-3’s. Factorial analyses, (site: front vs rear) and lameness score (0-3) and their interaction was used to evaluate effect of treatment. Consistent with published literature, rear legs were more affected by lameness than front legs (73% rear, 27% front). Only two categories for hoof lesions (white line lesion and heel erosion) were prevalent in this population. White line lesion severity increased with increasing lameness score and differed between site (P < 0.05). In contrast with literature, more white line lesions were prevalent in front vs rear. Hoof hardness was scored at 5 locations on the bottom of the hoof. At the toe tip only, there was a trend (P = 0.052) for hoof hardness to decrease with increasing lameness score, but no effect of site (P = 0.39) or interaction. Among force-plate measurements, there was a significant effect of lameness (P < 0.05) for maximum force, range (95th percentile-5th percentile), standard deviation of force, amplitude of weight-bearing (average of all positive peaks), amplitude of weight-removing (average of all negative peaks), but no significant effect observed for average force, weight shift (# of peaks/min) or contralateral ratio. On average, more weight was applied to front vs rear [30.4 vs 19.6%; (P < 0.05)]. Although further validation is warranted, these results indicate that these objective measures of lameness were sensitive enough to detect differences between lame vs non-lame pigs.