The effects of different levels of turmeric powder in diet on growth performance, carcass traits and economic parameters in broiler chicken

Introduction
Phytogenic products have been used as food spices and traditional remedies has a long history in different worldwide nations, but their application in poultry feed industry is almost new. Phytogenic feed additives are natural products originated from different parts of the plants, mostly in the form of powder or extracts. Researches with phytogenic agents have shown various characteristics such as anti-oxidative and antimicrobial effects, regulation of the gut function, and growth promoting effects for this products. They also have been noticed as potential alternatives for antibiotic growth promoters especially after the ban on antibiotic growth promoters in animal feed industry by European Union due to concerns about their residues in animal tissues and subsequent induction of bacterial resistance. It has been shown that the dietary incorporation of herbs and their associated essential oils may provide beneficial effects on poultry performance and health due to the antimicrobial activity of their phytochemical components Turmeric (Curcuma longa) is a member of Zingiberacae family and contains curcumin and its different derivatives as active constituents. Antioxidant, anti-inflammatory and nematocidal activities of turmeric and their relative constituents have been demonstrated in numerous researches. However, the benefits of an additive in animal nutrition matters little if it fails to show a significant economic improvement. Therefore, the objective of the present study was to assess the effects of addition of different levels of turmeric to diet on the growth performance and some economic indicators of broilers production.

Materials and Method
To investigate the effect of turmeric addition in diet on growth performance, carcass traits and economic parameters of broilers, a completely randomized design was conducted. Three experimental diets having 0% (control), 0.25% and 0.5% Turmeric were fed to 120 mixed sex of Ross 308 day-old chicks. Chickens were randomly distributed into 12 pens, so as to have 4 replicate per treatment and 10 chicks per pen. The experiment lasted for 42 days. Average body weight gain, feed intake, feed conversion ratio, breast muscle and thigh muscle relative weights and economic indexes were used as a criteria of response. Relative weight of internal organs including heart, liver, gizzard, spleen and bursa of fabricius and abdominal fat were also recorded. Diets were formulated to meet nutrient requirements of chicks according to the Ross 308 Management Guideline (2009) in three periods of starter (0-10 days), grower (11-24 days) and finisher (25-42 days). Feed and water were provided ad libitum. All chicks were vaccinated against Newcastle, Bronchitis and Inflammatory bowel disease, according to the regional vaccination program routine. Body weight and feed intake of chickens were recorded on days 1, 10, 24, 28, 35 and 42 of experimental period and the feed conversion ratio calculated for days 10, 24, 42 and feed cost of each pen, feed cost to weight gain ratio, production efficiency and monetary return calculated for days 28, 35 and 42. At the end of experimental period, 1 chicken per pen was slaughtered, and carcass cuts including breast muscle, thighs, and back bone, neck and wings were weighed in fresh and empty carcass was calculated as sum of these parts. Abdominal fat, heart, liver, spleen and bursa of fabricius were separated and weighed and percent of each part per live weight was calculated. The data were analyzed as a completely randomized design by analysis of variance (ANOVA), using the general linear model (GLM) procedure of SAS (2001). Means were compared using Duncan's Multiple Range Test with accepted level of significance of 0.05.

Results and Discussion
The results of this experiment showed that, addition of turmeric powder in broiler diet has no significant effect on feed intake, average weight gain or feed conversion ratio. Carcass traits including percentage of breast muscle weight (21.66, 22.78 and 21.62 % respectively in control, 0.25% turmeric and 0.50% turmeric groups), thighs muscle weight (19.98, 19.31 and 20.01% in control, 0.25% turmeric and 0.50% turmeric groups, respectively) and empty carcass weight (58.62, 59.16 and 59.43% in control, 0.25% turmeric and 0.50% turmeric groups respectively) relative to live weight also were not significantly affected by addition of turmeric powder in diet, however abdominal fat was significantly decreased in both turmeric containing treatments (2.98 and 2.90 respectively in treatments containing 0.25 and 0.50 percent turmeric powder vs. 3.31 percent in control group, p<0.05). This may indicate an improvement in fat metabolism of chickens and can be important in terms of human health. Relative weights of internal organs (heart, spleen, liver and bursa) were not significantly different among experimental treatments (p<0.05). Our findings also revealed a significant reduction of production efficiency in 0-28 days period (242.90 vs. 262.90) and monetary return (25452.25 vs. 29445.00) compared to control group as a result of 0.25% turmeric powder addition to feed (p<0.05). Addition of 0.50% turmeric powder didn't affect production efficiency and monetary return, however resulted statistically insignificant increase in feed cost compared to control group (66908.75 vs. 64535.00 rials/kg of weight gain).

Conclusion
Based on results of this experiment, it can be concluded that, addition of turmeric powder in levels used in this experiment (0.25% and 0.50% of feed dry matter) had no beneficial effect on feed intake, growth performance or most of carcass traits. However, the reduction of abdominal fat in turmeric containing treatments was noticeable, usage of turmeric powder as broilers feed additive cannot be recommended in commercial farms because of its negative effects on economic parameters of boilers production. More experiments with different levels of turmeric or in challenging environment may be needed to illuminate beneficial effects of turmeric in broiler feed.