176 Comparing the efficacy of different organic zinc sources on growth performance of broiler chickens

Abstract

Organic minerals are those bonded to one or more carbon-containing molecules to increase their bioavailability. Most common ligands are proteinates, amino acids and small peptides. Not all organic minerals are equivalent, their quality depending on strength and stability of the bond with the ligand, but also on the type of ligand as it’s defining its absorption pathway and efficiency. This study aimed to compare different organic Zn sources effectiveness on broiler chickens performance. The feeding trial was carried out at the Federal University of Viçosa, Brazil. A total of 2000 one-day-old male Cobb 500 chicks of 50 g initial body weight were weighed individually and by pen for equal weight distribution and placed into 24 pens. Chickens were assigned to 10 treatments with 10 replicates (20 birds/pen) and raised for 42 days (factorial design 5 x 2; 5 Zn sources vs 2 levels). The nutritional program consisted of 2 diets: 1–21 days and 21-42 days, formulated to meet or exceed the nutritional requirements for broilers according to Rostagno et al., 2017. Treatments differed by the mineral source and by Zn level (40 or 80 mg/kg). Four types of organic Zn were used: Zn Proteinate, Zn Glycine, Zn Methionine, Zn amino acids chelate and one inorganic form, Zn sulfate. Chickens had ad libitum access to water and feed in mash form. Performance parameters were recorded 1-21, 21-42, and 1-42 days by pen. Production efficiency index calculated as follows: PEI= (weight gain x survival) / (age of slaughter in days x FCR) x 100. Statistical analysis performed using PROC GLM of SAS software, by comparing the different Zn sources by Two-way ANOVA, Duncan’s test, p< 0.10. Broiler chickens fed Zn amino acids chelate had most efficient FCR in both 40 and 80mg/kg feed levels, optimized by -2 pts and -5 pts, respectively (Zn 80mg, p=0.0346). Likewise, chickens fed Zn amino acids chelate had higher weight gain and thus higher final weight at 42 days, +42g and +57g, respectively (Zn 80mg, p=0.0936), compared to other sources. Feed intake was similar for all Zn sources except for Zn-Methionine which increased intake (+170g) and higher weight but worse FCR at Zn 40mg/kg level. These results highlight the differences in terms of efficacy of different Zn sources (inorganic and organic) and even within organic sources, variability is observed. It emphasizes the importance of careful evaluations of technical and economic performance for decision-making in animal nutrition strategies.