Effect of Zinc Source and Dietary Level on Zinc Metabolism in Holstein Calves

Abstract

Forty-eight Holstein male calves were stratified by origin and body weight and randomly assigned to one of 4 treatment groups. Dietary treatments were administered in 2 phases. In phase 1, treatment groups received the basal diet with no supplemental Zn (control), basal diet plus 20 mg of Zn/kg of DM as ZnSO4 or Zn proteinate (ZnProt), or basal diet plus 20 mg of Zn/kg of DM with 50% of the Zn supplied from each source (ZnM) for 98 d. In phase 2, calves continued to receive the same Zn source fed in phase 1; however, half of the calves in each treatment group were randomly selected to receive 500 mg of Zn/kg of DM (HiZnSO4, HiZnProt, HiZnM) for 14 d. Gain, feed intake, and feed efficiency of calves were not affected by treatment in either phase of the experiment. Treatment had no affect on plasma Zn concentration or alkaline phosphatase activity in phase 1, but liver Zn concentration was greater in calves fed ZnSO4 than those fed ZnProt. In phase 2, plasma Zn was greater in calves fed HiZnProt and HiZnM than in those fed HiZnSO4. Liver Zn was greater in calves fed HiZnProt than in those fed HiZnSO4. Duodenal Zn concentrations were greater in calves supplemented with HiZnProt and HiZnM than those supplemented with HiZnSO4. Liver metallothionein was greater in calves that received 500 mg of Zn/kg than in calves that received 20 mg of Zn/ kg, but was not affected by Zn source. Calves fed HiZnProt and HiZnM had greater kidney Zn concentrations than those fed HiZnSO4. Heart, spleen, testicular, and bone Zn concentrations were not affected by Zn source. Hoof wall samples contained nearly 3-fold greater Zn concentrations than hoof sole. Calves fed ZnSO4 had greater Zn concentration in hoof wall samples than those fed ZnM. Hoof sole Zn concentration was not affected by Zn source or concentration. Plasma and tissue Zn concentrations at harvest were generally similar in calves supplemented with 20 mg of Zn/kg from ZnSO4 or ZnProt. However, when supplemented at 500 mg of Zn/kg, ZnProt was absorbed to a greater extent than ZnSO4, based on higher plasma, liver, duodenal, and kidney Zn concentrations.

The bioavailability of different chemical forms of zinc in fattening lambs

“…Kincaid et al (1997) indicated that application in calves' nutrition of zinclysine and zinc-methionine in amount of 300 mg of Zn/kg of feed caused the increase of content of this element in liver in comparison with animals received zinc oxide. The higher zinc content in calves tissues (Wright & Spears 2001) and lambs (Cao et al 2000) indicated also comparison the availability of zinc from zinc-proteinate and zinc sulphate. The application of different forms of zinc changed the pathways of absorption of this element.…”

Scientific Opinion on the potential reduction of the currently authorised maximum zinc content in complete feed

“…Young calves fed milk replacer tolerated 500 mg Zn/kg diet for five weeks without adverse effects, but 700 mg/kg diet caused a reduction in weight gain, feed intake and feed efficiency (Jenkins and Hidiroglou, 1991). Wright and Spears (2004) administered a diet containing 530 mg Zn (from zinc sulphate, zinc proteinate and a mixture of both zinc sources)/kg diet to Holstein calves for 14 days to evaluate the effects of dose and source on metabolism and zinc tissue concentrations; no adverse effects were recorded. Arelovich et al (2000) administered zinc chloride by ruminal cannulas to provide the equivalent of an additional 30, 250 and 470 mg Zn/kg diet to heifers that were fed prairie hay and urea.…”

“…Zinc is regulated at the intestinal level in the target animals. With the exceptions of liver and kidney (Eisemann et al, 1979;Jenkins and Hidiroglou, 1991; Cao et al, 2000; Gallaher et al, 2000;Wright and Spears, 2004; see also review of Schlegel et al, 2013), zinc concentrations exceeding the requirements up to about 200 mg/kg feed will not result in a change of zinc concentrations in animal tissues (Jenkins and Hidiroglou, 1991), and other products including milk (Schwarz and Kirchgessner, 1975; Miller et al, 1989;Wiking et al, 2008; Peters and Mahan, 2008; Peters et al, 2010). Consequently, a reduction in dietary zinc in the range between requirements and 150 mg/kg feed will affect zinc concentration only in liver and kidney.…”

Organic zinc supplementation in the dry season in nelore bulls and its effect on spermiogram

“…Nevertheless, some studies report a higher zinc serum concentration in animals feed a diet supplemented with excess zinc, when compared to a control diet (WRIGHT; SPEARS, 2004).…”