An investigation into the effects of supplemental ferrous sulfate consumption and time period on growth performance, carcass characteristics, and hematological indices of broiler chickens

Iron is an essential trace element for all living organisms. It plays an important role in many metabolic processes and required for synthesis of DNA, RNA and proteins. It is essential for cellular enzymes of oxidases, catalases, peroxidases, cytochromes, ribonucleotide reductases, aconitases, and nitric oxide synthases (Dallman 1982; Lieu et al. 2001). Unfortunately there are millions of people in the world who suffer from deficiency of essential trace element such as iron and zinc and according to World Health Organization (WHO) iron deficiency is the most common nutritional disorder in the world and it has epidemic proportions (Lopez et al. 2002; Abbaspour et al. 2014). The iron (Fe) requirement of broiler chicks has been reported to range from 40 to 80 mg Fe/kg diet (Vahl London and Klooster, 1987; NRC, 1994). Vahl London and Klooster (1987) found that increasing level of dietary inorganic Fe from 0 to 180 mg/kg increased haematological indices such as Hb and TIBC in broilers. Also, Yang et al (2011) reported that inclusion of inorganic Fe into broilers diet had no effect on growth performance.

A total of 450 one-day-old Ross 308 male broiler chicks were used as 3×3 factorial design with three levels of 0.0, 40 and 80 mg/kg supplemental Fe (FeSO4.7H2O) during total (T: 1-42 days of age), grower and finisher (GF: 11-42 days of age) and finisher (F: 25-42 days of age) periods. The basal diet included corn-soybean meal with 85.40, 83.72 and 84.37 mg Fe per kg diet in starter, grower and finisher feeding phases, respectively. On the 42 day of the study, final body weight, average daily feed intake (ADFI), average daily weight gain (ADWG) were recorded and feed conversion ratio (FCR) was calculated for whole experimental period. Mortality rate was recorded daily and used to adjust the FCR. After slaughtering and removal of skin and feather, whole carcass, breast muscle, thigh muscle, and abdominal fat were excised and weighed individually. Yields were expressed as the percentage of live body weight. At 42 days of age, blood samples were obtained via wing vein of 5 birds in each treatment and collected into vials containing EDTA. The red blood cell (RBC) and white blood cell (WBC) counts were determined by a hemocytometer method using Natt-Herrick solution; hematocrit (HCT/PCV) and hemoglobin (Hb) values were measured by microhematocrit and cyanmethemoglobin methods respectively (Kececi et al., 1998). The mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) were computed according to Campbell (1995). Also, whole serum iron and total iron binding capacity (TIBC) were determined by methods described by Fairbanks (1999) and Andrews (2010), respectively.

The results showed that supplementing basal diet with 80 mg/kg FeSO4 significantly (p < 0.001) decreased ADFI in broilers during T period. However, supplemental Fe from dietary groups at different periods had no significant effect on ADWG and FCR. Similar to present study, Mrkaljevic (2014) observed no effect of high levels of iron (140 to 240 mg/kg) on growth performance. It seems that high levels of dietary Fe rather than recommended level in NRC (1994) does not lead to significant effect on production performance, because iron intake can be limitedly absorb and the rest of iron intake will be finally excreted. Also, adding FeSO4 significantly (p < 0.05) increased the yield of thigh and breast muscle of birds at T and GF periods, respectively. Compared with birds fed the diet supplemented with 80 mg/kg of FeSO4, abdominal fat percentage of birds fed control diet and 40 mg/kg FeSO4 significantly influenced during the T period (p < 0.001). The control of lipid deposition in broilers aimed at efficient lean-meat poultry production is of current interest and any reduction in the amount of abdominal fat is considered to be positive by both producers and consumers (Hermier, 1997). It was reported that the high prevalence of micronutrient deficiencies such as iron, zinc, vitamin A, vitamin E and vitamin C might be contributing to the development of obesity (Garcia et al. 2013), and these micronutrients decrease or inhibit the expression of leptin, in both humans and animal models (Garcia et al. 2013; Garcia-Diaz et al. 2010). Microcytic hypochromic anemia is the most important anemia in poultry. This type of anemia can be seen in iron deficiency when the MCV, MCH and MCHC are reduced (Weiss and Wardrop, 2010). Blood hematological indices such as Hb, HCT, MCV, MCH, serum Fe concentration and TIBC was increased in chickens fed 40 and 80 mg Fe/kg compared to control diet (p < 0.01). Blood parameters are good indicators of physiological, pathological and nutritional status of an animal and changes in hematological parameters demonstrate the effect of dietary factors and additives in the diet of any living creature (Ganong, 1999). Increased hematological indices such as Hb and HCT, which are the main indicators in estimating iron requirements for broiler chickens, indicate the supply of iron requirements in broiler chickens and physiologically, they provide bird health (Ma et al. 2016). In the current study, the use of additive levels of iron sulfate supplementation from 0 to 80 mg/kg resulted in an increase in serum iron levels in broiler chicks. It was demonstrated that serum iron is typically decreased in iron deficiency and in inflammatory diseases (Weiss, 2010).

It was concluded that use of 40 and 80 mg/kg FeSO4 had no remarkable effect on performance, but can be improved hematological status of broiler chicks by elevating of Hb, PCV, MCV, MCH, serum iron concentrations and reducing TIBC value.