Influence of chelated iron supplement containing organic acids and amino acids on growth performance, skeletal growth indices, fecal score, and blood parameters in suckling calves

Minerals are a small part of the diet, but their deficiency has major consequences for the health and reproduction of animals. Iron is not only one of the most abundant elements on Earth (it is the fourth most common element in the Earth's crust), but it is also a vital component of living things and an essential nutrient for all animal species. The main source of iron for calves and other newborn ruminants is milk or milk replacer. Milk contains relatively small amounts of iron, and calves are prone to iron deficiency. In most dairy farms, iron supplements are added as an inorganic source to the diet, which can undergo oxidation and react with other substances, causing a decrease in solubility. To solve this problem, the desired elements should be added to the ration of livestock in the form of chelated supplements. Research shows that iron plays an essential role in several metabolic processes and is necessary for the synthesis of DNA, RNA, and proteins in the body. Dietary supplements with iron have increased hematology parameters and improved growth. In addition, the presence of iron in the diet is effective in increasing appetite and glucose metabolism. Based on this, this study was conducted to investigate the effect of chelated iron supplement containing organic acid and amino acid on the performance, skeletal growth indices, fecal score, and blood parameters of suckling calves.
36 newborn male calves (with an average weight of 35.1±2.7 kg) were randomly divided into three groups with 12 replicates. The treatments included the control group (basic diet without iron supplement), basic diet with chelated iron supplement containing organic acid, and basic diet with chelated iron supplement containing amino acid. The length of the trial period was 63 days. During the experiment, calves were kept in separate locations. The rations were based on the National Research Council (NRC) report which was published in 2001. The rations were provided by total mixed ration (TMR) in calves at 8 am and 4 pm and animals had free access to water. Milk feeding was also performed in the morning and evening (10% of body weight). Calves were weighed every 21 days. The amount of feed consumed and post-feed was recorded daily. Skeletal growth in the body was measured using a standard measuring device and caliper. Three days a week, the calves' feces were randomly evaluated. On the last day, three hours after the morning meal, calves were sampled from the veins and blood parameters were determined. Sampling was done using venoject tubes with and without heparin and the samples were immediately centrifuged at 3000 rpm for 10 minutes to separate the plasma and kept at -20ºC until the day of the experiment. Glucose, urea, triglyceride, cholesterol, total protein, albumin, and globulin were determined using a Pars Test automated analyzer and kit. The measurement of mineral elements in blood serum (iron, zinc, copper, calcium, and phosphorus) was done by atomic absorption device.
The results showed that calves receiving chelated iron supplements with amino acids had an increase in the final weight, total period weight, and daily weight, and a decrease in feed conversion rate compared to the control group and treatment receiving chelated iron supplements with organic acids (P<0.05). Also, there was no significant difference in terms of dry matter and milk consumption among different treatments. There was no significant difference in terms of skeletal growth indices among different treatments. Fecal score and diarrhea status improved in both treatments receiving iron supplements (P<0.05). Consumption of iron supplements by calves in both chelated forms containing organic acids and amino acids increased blood glucose and iron and decreased blood copper and phosphorus (P<0.05). However, cholesterol, triglyceride, urea, total protein, albumin, and blood globulin were not affected.
In general, according to the results of this research, the intake of chelated iron with amino acids is recommended due to the improvement in the performance of suckling calves.