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Creating a Zn deficient model to understand the impact of different Zn sources on performance and oxidative status in pigs
The objective of this study was to create a Zn-deficient model, and to investigate the impact of three difference Zn sources on growth performance, immunity, and oxidative status in pigs. A total of 128 nursery male pigs were used. All pigs were fed a common Zn-deficient semi-purified diet (corn grit, soy concentrate) for 21 days, and started the dietary treatments on day 22 for three weeks (42 days of age, BW 12.2 kg). There were four treatments with eight replicates per treatment and four pigs per pen. The four treatments included: a negative control without Zn supplementation, three Zn groups supplemented with 40 ppm Zn from either Zn(HMTBa)2 (Novus International Inc, St Charles), ZnO, or glycine-Zn. One pig per pen close to average pen weight was killed at the end of study for tibia weight, tibia Zn (dry weight basis), plasma TBARs, free carbonyl, and hepatic vitamin E measurement. Data were analyzed with PROC GLM one-way ANOVA. After 21 days period of Zn depletion, typical Zn-deficient symptoms were observed in most pigs including parakeratosis (skin lesion), hair over-growth, and anorexia. Five days after repletion, Zn supplementation groups had better ADFI (P<0.01), ADG (P<0.01), and FCR (P<0.01) than the non-supplemented control. Among the three different Zn sources, pigs fed Zn(HMTBa)2 gain more than pigs fed ZnO (21%, P<0.05), and had better FCR (11%, P<0.05). The pigs fed Zn-glycine were intermediate. Tibia weight (both tibias) was increased with Zn(HMTBa)2 supplementation compared to the control (P<0.05) while ZnO supplemented pigs were intermediate. Compared to the control, tibia Zn (dry basis) was increased 34%, 56%, and 112% with ZnO, Zn-glycine, and Zn(HMTBa)2, respectively (P<0.01). Pigs fed Zn(HMTBa)2 had significantly high tibia Zn concentrations than pigs fed ZnO (P<0.05). No difference was observed in immunity and oxidative status (P>0.10). In summary, Zn deficiency (parakeratosis ) was observed in pigs fed Zn-deficient semi-purified diet for 21 days. Pigs fed Zn deficient diet had reduced feed intake and retarded growth. Among the three Zn sources, both organic Zn (Zn(HMTBa)2 and Zn-glycine) are more bioavailable than ZnO based on performance and tibia Zn levels.
Keywords: Zinc, parakeratosis, swine, organic Zn