Jennifer Lindel  R&D Manager/ AR&GE Yöneticisi Biochem Zusatzstoffe GmbH

Pietro Antonio Quaglia  Tech. Sales Manager/Tek. Satış Müdürü Biochem Zusatzstoffe GmbH

Dr. Bastian Hildebrand  Technical Manager/ Teknik Müdür Biochem Zusatzstoffe GmbH

Several environmental as well as animal-related factors are influencing the demand for trace minerals in the feeding of broiler chickens. Moreover, diet composition and source of supplemented trace minerals have a significant effect on required inclusion level.

VARIETY OF EFFECTS Stable performance is based on various functions of trace minerals. Zn, Mn, Cu and Fe are of crucial relevance for the expression of several parameters (Table 2). Lesions on the ventral foot-pads, skin dysfunctions and issues with bone health (perosis, tibial dyschondoplasia) are prevalent problems in poultry production. Improving of these reported factors not only benefits to a higher growth rate and welfare but also to a better carcass quality and a higher economically output at the processing plant. Particularly Zn, but also Mn and Cu are needed for optimal development and regeneration of epithelial tissues and can affect incidence and severity of skin and foot-pad lesions. The availability of Cu, Mn and Zn affects bone flexibility, tensile strength and growth of bones, especially in early skeletal development. A high trace mineral status of birds is known to benefit skin quality and intestine strength. Consequently, the occurrence of skin tearing and hence invasion by pathogens can be decreased during processing at the slaughterhouse.

EFFICIENT ABSORPTION It is widely accepted that trace mineral sources of high absorbability help to benefit a stable animal performance and allow to reduce mineral excretion into the environment. Various studies on the replacement of inorganic trace minerals by organically bound forms have been conducted and chelate compounds of Zn, Mn, Cu, and Fe are reported to be higher bioavailable in contrast to sulfate or oxide salts. The major advantage of chelated trace minerals is their stability in the upper gastro intestinal tract. Due to this stability they are much more resistant than most inorganic salts against dissociation in the crop, proventriculus and gizzard. This allows an efficient and “protected” transport of metals to the intestinal epithelium and finally a high absorbability. Chelated forms are increasingly used in poultry production nowadays. However, binding forms can differ in their efficacy, according to production process, metal: amino acid ratio, and degree of chelation. Glycine-bound trace minerals are of interest, because of their high metal content, as well as due to the essentiality of glycine under the light of protein-reduced diets in broilers. In practice a partial replacement up to 50% of trace minerals from inorganic sources by glycine chelates is a widely used strategy to improve the safety of metal supply without increasing the trace mineral level in feed. This is especially recommended in situations of increased stress and presence of dietary mineral antagonists.

NEW DATA ON IMPACT OF TRACE MINERAL SOURCE In order to compare the efficiency of trace mineral compounds in supporting the animals’ supply status, measurements of absorption and retention provide the most valuable information. In a depletion study recently conducted by University of Berlin and Biochem, it was stated that in situations of suboptimal trace mineral status, the use of glycine chelates (E.C.O.Trace®) has beneficial effects on the absorption of Zn, Mn, Cu and Fe compared to sulfate forms. Seventy-two 1-day-old male broiler chickens (Cobb 500) were divided in three feeding groups. All birds were fed for 14 days a basal diet containing only native contents of trace minerals. In the subsequent 14-day repletion two feeding groups were supplemented according to official feeding recommendations (NRC, 1994), either with glycine-bound trace minerals (Gly,) or sulfate-bound trace minerals (Sul). For calculation of digestibility, one group received the basal diet without addition of Fe, Mn, Zn and Cu. Significant differences in apparent total tract digestibility between group Gly and Sul were detectable for Zn, Cu and Mn (Fig. 1). The trace mineral supplementation improved the body weight gain and feed conversion ratio in comparison to inorganic salts (Fig. 2). Moreover, the trial demonstrated a higher accumulation rate with glycinates in contrast to the sulfate group (Fig. 3 and Fig. 4).

IMPLICATIONS Availability of inorganic trace element compounds is limited; therefore, safety margins are commonly used to ensure the fulfilment of the birds’ demand. The current trial results confirmed higher values in bioavailability of trace minerals from glycine chelates compared to sulfates. This allows a safer supply and an improved trace mineral status in modern broiler breeds compared to sulfates. Regarding the crucial role of trace minerals for skin integrity, immune system and build-up of cartilage and bones, these highly bioavailable mineral source is an efficient tool to support an optimal growth of broiler chickens. Especially in critical situations of increased demand a safe trace mineral supply is of high relevance for reducing the risk of subclinical deficiency and for supporting animal health, welfare and performance. Because of the better digestibility, glycine chelates can replace high dosages of inorganically bound trace minerals, which contributes to lower mineral excretion and consequently effects the environment.

Note: References are available on request from the authors.