Impacts of Chelated Iron Supplement with Organic Acid and Amino Acid on Growth Performance, Nutrient Digestibility, Feeding Behaviors, and Blood Parameters in Suckling Calves

Background: Milk contains a relatively small amount of iron, and one of the most important negative aspects of milk nutrition is the occurrence of digestive diseases, such as diarrhea.Its iron concentration is in the range of 0.3-0.6 mg/kg.Calves are prone to iron deficiency.Iron is an essential component of hemoglobin, myoglobin, and several enzymes such as catalase, peroxidase, and cytochrome oxidase.In the early stages of life, calves do not have a functional rumen, and it seems that they are more like monogastric animals that must obtain the nutrients they need.They also suffer from a lack of immune systems.Therefore, this condition exposes them to critical challenges, mainly the risk of disease and death.Iron requirements of animals vary depending on their age, sex, and physiological stages.The iron requirement for calves is estimated to be around 100 ppm, and it is generally believed that young cows need more iron than mature animals.In most dairy farms, iron supplements are added to the diet from an inorganic source, which can undergo oxidation and react with other substances, thereby decreasing solubility.For the purposes of animal nutrition and increasing bioavailability, this research focuses on the use of chelates or preparations of protein iron.By using additives containing iron compounds, bioavailability can be increased by chelation, which consists of a double covalent bond of the metal with amino acids.To solve this problem, the desired elements should be added to the diets of livestock in the form of chelated supplements.This research was designed to investigate the effect of a chelated iron supplement containing organic acids and amino acids on the performance, digestibility of nutrients, feeding behaviors, and blood parameters of weanling calves.Methods: Thirty-six newborn male calves (with an average weight of 35.1 2.7 kg) were randomly divided into three groups with 12 replications.Experimental treatments were a control group (without iron supplementation), diets supplemented with 50 mg of chelated iron based on organic acids per calf per day, and diets supplemented with 50 mg of chelated iron based on amino acids per head of calf per day.First, all the calves were carefully examined to ensure their health and performance.The duration of the experiment was 63 days.Calves were weighed every 21 days, and the amount of consumed feed was recorded daily after 16 hours of starvation after feeding using a digital scale.The feed consumption of each animal was also calculated from the difference in the given diets and the remaining manger of each animal.The increase in the amount of feed given to the animals was determined based on the feed of each animal on the following day.The feed of the animal would increase if the animal left less than 10% feed on three consecutive days.Diets were adjusted based on NRC (NRC, 2001) completely mixed, and provided to the calves two times: 8 in the morning and 4 in the evening.Animals had free access to water.Calves were also milked twice in the morning and in the evening (at the rate of 10% of body weight).For the samples of digestibility, the samples of feed, residues, and feces were first collected from each animal on days 58 to 63 for 5 days.To measure blood metabolites, blood was sampled from the calf's jugular vein on day 63.Blood samples were transferred into anticoagulantcontaining tubes.To prepare plasma, blood samples were centrifuged at 3000 rpm for 10 min, and plasma samples were transferred to -20 C until analysis.