Poultry industry in India had a remarkable growth during the past two decades, which was highly witnessed by its major contribution to the agricultural sector in general and livestock sector in particular. Poultry meat is the main quality of protein provides to meet the ever growing demand of the human population in India and it is one of the cheapest good quality animal protein to reduce protein hunger even in rural areas. There has been considerable research interest in the utilization of chromium (Cr) in livestock and poultry feeds. Chromium is an essential element required for carbohydrate, lipid, protein, and nucleic acid metabolisms, activating certain enzymes and stabilizing proteins and nucleic acids. The primary role of chromium in metabolism is to potentiate the action of insulin as a component of Glucose Tolerance Factor (GTF). Moreover, chromium is known to enhance the action of insulin and directly involved in carbohydrate, fat and protein metabolism. The beneficial effects of chromium can be observed more efficiently under environmental, dietary and hormonal stresses.
Absorption and excretion
According to NRC (1997), the Cr picolinate (CrPic) form is a distinctive molecule (Cr combined with picolinic acid) which helps the body to absorb it. It is excreted primarily in urine either freely or bound to low molecular weight organic transporters. The retention of chromium may relate to absorption patterns of various organic/inorganic sources of chromium. According to Amatya et al. (2004) Cr-yeast complex might be absorbed better than K-chromate and Cr-chloride. chromium is mainly accumulated in kidney, liver and muscle. One of the reasons of the enhanced retention may be the unavailability of chromium chromium in the basal diet of the birds which triggers the retention of the essential element in the gut. On the other hand, stressors cause depletion of chromium through altered glucose metabolism. chromium supplementation may improve functioning of pancreas with regards to secretion of digestive enzymes, which improves the retention of nitrogen and minerals. Due to the anti- oxidative role of chromium, it is possible that chromium may exert a protective effect on pancreatic tissue which results in increased pancreatic functions comprising of the release of digestive enzymes and an enhanced nutrient utilization.
Chromium is an essential element useful for metabolism of food in the body. Being a part of Glucose Tolerance Factor, the prime role of chromium regarding metabolism is mediated through activating insulin and helps insulin to progress glucose into the cell for energy production. Insulin controls the metabolism of carbohydrate, protein, fats and stimulates the uptake of amino acids and protein synthesis and also the glucose utilization. Chromium acts as cofactor of insulin activity and the presence of this mineral is needed for maintaining proper glucose metabolism and growth in animals and poultry. Addition of chromium in poultry diet may boost the utilization of dietary energy through stimulation of insulin action and thus could help maintain productivity of birds even if the dietary energy level is lowered. Dietary supplementation of organic chromium in commercial broiler chickens ameliorates oxidative stress by reducing lipid peroxidation and increasing the activities of plasma glutathione peroxidase and glutathione reductase.
Supplementation of chromium at different levels in non-ruminants species increases the carcass quality and decrease the body fat content. Many studies support chromium supplementation in the poultry diet to improve performances during heat stress . Increase in body weight mainly due to reduced stress during feeding and watering and increased absorption of nutrients due to efficient glucose transport mechanism as influenced by the chromium levels. Organic chromium helps insulin receptor site on muscle cell to work more efficiently. Insulin receptors on the outer part of a cell allow the cell to bind with insulin in the blood, this activates the glucose transporters to take up glucose from the blood and use it for energy which results in improved glucose absorption in muscles. This in turn increases the body weight for better feed efficiency Al-Mashhadani et al. (2010).
Laying hen performance
The chromium supplementation found to improve feed efficiency, egg production, egg weight, shell thickness, albumen index and weight as well as yolk weight and index in layers. chromium augments egg quality by acting as a structural component of egg albumin or in cross linking of protein, necessary for the synthesis of ovomucin and facilitates the transfer of cation into the albumin of egg during the plumping process in the uterus.
In non ruminant diets, reduction of blood cholesterol with addition of chromium is observed as the main response regarding lipid metabolism, which may be on account of an enhanced activity of insulin that decreases lipolysis and increases fatty acids assimilation in the adipocytes. Liver is the key organ of cholesterol synthesis in laying hens and chromium improves the cholesterol profile through accelerating the activity of Lecithin Cholesterol Acyltrasnferase (LCAT), cholesterol esterification and excretion. Chromium can increase liver LDL receptors and could decrease the LDL levels and in parallel activity the HDL fraction gets increased.
In many studies, addition of chromium in poultry diet results in low mortality. The reduction in the mortality in poultry due to the beneficial effect of chromium in enhancing the immune system and also due to stress relieving effect of chromium. The dietary use of organic and inorganic chromium (chromium chloride, chromium L-methionine) showed a significant increase in antibody responses, improved H/L ratio, CMI (Cutaneous Basophil Hypersensitivity (CBH) response test to PHA-P) as well as relative weights of thymus and spleen in broilers reared under heat stress Uyanik et al.,2002). The organic form was found to be better in reducing heat stress-related immunodepression in broiler chicks.
Chromium is an essential mineral element that plays important role in livestock and poultry nutrition. Dietary chromium (Cr) has useful effects on feed consumption, nutrient digestibility, antioxidant machinery, growth and production performances and egg qualitative traits. It is also very helpful especially in poultry under heat-stress environmental conditions. The requirements of different classes of poultry and the quality of the different trace minerals used are the areas that warrant attention. Extensive research works may be carried out for studying the chromium enriched poultry products on the beneficial effects of health conscious consumers.
Senior Research Fellow, Directorate of Distance Education, TANUVAS, Nandanam-51.
Al-Mashhadani,E.H., Dhia K.Ibrahim and Luma K.Al.Bandr, 2010. Effect of supplementing different levels of chromium yeast to diet on broiler chickens performance. Int. J. Poult. Sci., 9(4): 376-381.
Amatya, J.L., S. Haldar and T.K. Ghosh, 2004. Effects of chromium supplementation from inorganic and organic sources on nutrient utilization, mineral metabolism and meat quality in broiler chickens exposed to natural heat stress. Anim. Sci., 79: 241-253.
National Research Council (NRC) 1997. The role of chromium in Animal nutrition. National Academy press, Washington DC.
Uyanik, F., S. Kaya, A.H. Kolsuz, M. Eren and N. Sahin, 2002. The effect of chromium supplementation on egg production, egg quality and some serum parameters in laying hens. Turk. J. Vet. Anim. Sci., 26: 379-387.