Plasma proteins and haematological parameters in fattening pigs fed different sources of dietary zinc.

The effect of varying amounts of sources of dietary zinc on some blood parameters and the plasma protein ratios of fattening pigs was studied. During a 30-day pre-trial period, 42 pigs were depleted of Zn and divided into three groups of 14 animals each. During the 105-day experimental fattening period two experimental groups (T1-2) were repleted with dietary Zn in the form of inorganic salt (ZnSO4) or metallo-organic chelate (zinc methionate, ZnMET), while the control group (C) received no extra Zn. The supplements contained 84.3 and 40.9 mg Zn/kg diet, respectively. The nutritional effects of Zn were evaluated on the basis of red blood cell (RBC) count, mean corpuscular volume (MCV), haemoglobin (Hb) concentration, packed cell volume (PCV), white blood cell (WBC) and thrombocyte count, plasma total protein, albumin, and globulin concentrations, and albumin/globulin (A/G) ratio. During the parakeratosis period (days 28-56) both the basic feed (group C) and the diet enriched with 40.9 mg Zn/kg (as ZnMET) fed to group T2 pigs resulted in a lower red blood cell (RBC) count, Hb concentration and PCV than in group T1 fed a diet containing 84.3 mg Zn/kg (as ZnSO4). Dietary Zn of organic and inorganic origin had no effect on MCV and on the WBC and thrombocyte counts of fattening pigs. At the start of the parakeratosis period (day 28), group C pigs had significantly lower, and by its end (day 56) significantly higher plasma total protein and globulin concentrations than pigs of group T1. At the same time, no significant differences were observed in albumin concentration between group C and the two experimental groups. Throughout the trial, feed containing sufficient, and insufficient, quantities of Zn from various sources had no influence on blood plasma alpha and beta globulin concentrations. In the second part of the experiment (day 56) dietary Zn deficiency resulted in a significantly higher level of gamma globulin in group C pigs than in pigs given sufficient Zn of inorganic origin. While inorganic Zn increased some of the blood parameters, namely RBC count, Hb and possibly PCV, organic Zn seemed to be responsible for raising the proportion of plasma globulins.