Evaluating the Influence of Different Recommended Dietary Levels of Cu and Zn on Finishing Pigs.

Meijun Li,Peng Liao,Wei Tang,Yunhu Li

doi:10.3389/fvets.2021.770195

Meijun Li, Peng Liao + Show 2 more

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https://doi.org/10.3389/fvets.2021.770195

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Abstract

This study was conducted to evaluate the effects of dietary supplementation of different recommended levels of Cu and Zn on antioxidant capacity, tissue mineral status, minerals excretion, meat quality, digestive enzyme activity, and metal transporters in finishing pigs. A total of 120 pigs (with an average initial body weight (BW) of 70.0 ± 2.1 kg) were randomly divided into four treatments: (1) basal diet without added Cu or Zn (control), (2) basal diet+35 mg cupreous N-carbamylglutamate chelate (NCG-Cu) +150 mg zinc-methionine chelate (Zn-Met) (AC), (3) basal diet + 3.0 mg of NCG-Cu + 43 mg Zn-Met (CN), and (4) basal diet + 3.5 mg NCG-Cu + 50 mg Zn-Met (NRC100). Pig growth performance was not affected by the level of Cu or Zn. Among the four treatments, the AC treatment had the highest concentration (P < 0.05) of glutathione peroxidase (GSH-Px). Pigs fed the AC diet had the highest (P < 0.05) liver Zn, fecal Cu, and fecal Zn among the four treatments. The protein levels of trypsin and aminopeptidase N (APN) in the intestinal mucosa showed their highest levels (P < 0.05) in the NRC100 and AC treatments. The mRNA levels of trypsinogen and APN were significantly up-regulated (P < 0.05) in the AC, CN, and NRC100 treatments compared with the control. The mRNA levels for the Zn transporter genes SLC30A1 (ZnT1) and SLC30A2 (ZnT2) were significantly up-regulated (P < 0.05) in the AC treatment, and the mRNA levels for SLC39A4 (ZIP4) and metallothionein 1 (MT) in the AC, CN, and NRC100 treatments were significantly up-regulated (P < 0.05) compared with the control. Meat quality were not affected (P > 0.05) by the different recommended levels of Cu and Zn. These results indicated that the supplemental Cu and Zn levels routinely used in AC diets in Chinese commercial feed enterprises should be reduced.

Highlights

Copper (Cu) and zinc (Zn) are essential mineral elements for all animals, including pigs and poultry, and often need to be supplemented in commercial feeds to prevent post-weaning diarrhea and as an alternative to in-feed antibiotics to stimulate growth and immune response [1,2,3,4]
NCG-Cu, cupreous N-carbamylglutamate chelate; Zn-Met, zinc-methionine chelate; DM, dry matter. aControl = basal diet. bAC = basal diet + 35 mg of supplemental Cu/kg from NCG-Cu + 150 mg of supplemental Zn/kg from Zn-Met. cCN = basal diet + 3.0 mg of supplemental Cu/kg from NCG-Cu + 43 mg of supplemental Zn/kg from Zn-Met. dNRC100 = basal diet + 3.5 mg of supplemental Cu/kg from NCG-Cu + 50 mg of supplemental Zn/kg from Zn-Met (100% of National Research Council (NRC) levels of Cu and Zn requirements). eMean values ± SD (n = 8)
NCG-Cu, cupreous N- carbamylglutamate chelate; Zn-Met, zincmethionine chelate. 1Control = basal diet. 2AC = basal diet + 35 mg of supplemental Cu/kg from NCG-Cu + 150 mg of supplemental Zn/kg from Zn-Met. 3CN = basal diet + 3.0 mg of supplemental Cu/kg from NCG-Cu + 43 mg of supplemental Zn/kg from Zn-Met. 4NRC100 = basal diet + 3.5 mg of supplemental Cu/kg from NCG-Cu + 50 mg of supplemental Zn/kg from Zn-Met (100% of NRC requirements for Cu and Zn); ADG, average daily gain; ADFI, average daily feed intake; F/G, feed-to-gain ratio

Summary

Introduction

Copper (Cu) and zinc (Zn) are essential mineral elements for all animals, including pigs and poultry, and often need to be supplemented in commercial feeds to prevent post-weaning diarrhea and as an alternative to in-feed antibiotics to stimulate growth and immune response [1,2,3,4]. Those minerals are essential components of several metalloenzyme systems, and Cu is surpassed only by Zn in the numbers of enzymes that it can activate for various biochemical programs, including normal growth and development of organs and the immune system [1, 4,5,6]. Limited data are available on the use of zinc-methionine chelate (Zn-Met) and cupreous N-carbamylglutamate chelate (NCG-Cu) as the only sources of Zn and Cu at NRC-recommended, MA-PRC-recommended, and actual Chinese feed industry levels in diets for finishing pigs

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