Effect of replacing inorganic with organic trace minerals on growth performance , carcass characteristics and chemical composition of broiler thigh meat

1 College of Veterinary Medicine, South China Agricultural University, 483 Wushan Road, Tianhe District, Guangzhou, 510642, China. 2 University of Veterinary and Animal Sciences, Lahore, Pakistan. 3 Department of Livestock, Balochistan, Pakistan. 4 Balochistan University, Quetta, Pakistan. 5 Lasbela University of Agriculture, Water and Marine Sciences, Uthal, Lasbela District, Balochistan, Pakistan. 6 Yunnan Provincial Key Laboratory of Animal Nutrition and Feed, Yunnan Agricultural University, Kunming 650201, Yunnan, PR China.


INTRODUCTION
It is well recognized that demand of poultry meat and meat products has increased due to shortage of red meat supply (FAO, 2010) and price phenomena.Annual broiler global meat production was 84.6 million tons in 2013 (USDA, 2003) and covered 33% of global meat demand (FAO, 2010).The genetic advancement continuously elevated the broiler growth potential; broiler can attain mature body weight by consuming less feed (Mckay, 2009) and in shorter period of time.It is well established that trace minerals are important for broiler normal growth and development (Kratzer and Vohra (in press)).However, due to relative less economic importance, trace minerals sector failed to attracts poultry scientist attentions.The current interest in trace minerals nutrition has been vigorously undertaken due to better bioavailability of trace minerals (Wedekind et al. 1992, Oyagi andBaker, 1993) and concerns of environmental pollution (Lesson, 2003).
Poultry nutritionists balance the trace minerals requirements according to National Research Council (NRC, 1994) recommendations (NRC, 1994).However, these recommendations have not supported well due to many factors such as FAO, (2010) Broilers growth potential elevated trace minerals requirement, (USDA, 2003) negative interactions between the inorganic forms of trace elements (Du et al. 1996), Mondal et al. 2007).Therefore nutritionists increased trace minerals supplementation levels much more than that of NRC (1994) recommendations (Inal et al. 2001;Lesson, 2005).The studies conducted in last decades have shown that organic trace minerals supplementation significantly improved livestock production (Paik 2001).The bioavailability of various forms of the organic trace elements is superior to that of inorganic element due to their better absorption rate (Lesson, 2003;Nollet et al., 2005;Van Der Klis et al., 2002).Organic trace minerals make complexes with organic molecules and attaining structure which can easily pass through intestinal mucosa (AAFCO, 1997;Kincaid, 1989;Nelson, 1988).
Pakistan has an agriculture based economy.About 70% of the total population is directly or indirectly involved in wide range of agriculture businesses.Livestock contributes about 55% of total the agriculture GDP and poultry sector has been expanding its wing as most integral and dynamic component of national economy (Anonymous, 2008).Commercial poultry sector is on the stage of rapid boom with annual growth rate of 20 to 25%.Kamal (2010), Pakistan Poultry industry has recommended the addition of organic trace minerals in poultry feed.However, industry is reluctant due to price Baloch et al. 1571 phenomena and availability.Keeping in view the result of available literature, the present study was planned to determine the effect of replacing the inorganic with organic trace minerals on growth performance, carcass characteristic and composition of thigh meat of broilers.

MATERIALS AND METHODS
The  (1994) recommendations.Analyzed by the AOAC (2000) and both feed were procured from commercial feed mill.The diets were fed adlibitum throughout experimental period.Dietary treatments were divided in different replicate pens A) x fed diet throughout trial period), B) fed diet (x) in week 1-4 and diet (y) was offered in last week.C) Diet (x) served weeks 1-3 followed by diet (y) week 4-5.D) First 2 weeks were fed diet (x) while, diet (y) offered in the last three weeks.In the treatment (E), only first week were fed diet (x) and remaining last 4 weeks were fed diet (y) while in treatment (F), complete diet (y) was fed to experimental birds.The initial temperature of house was maintained at 95°F at chick level and was reduced by 5°F every week to maintain the final temperature at 75°F.

Growth performance
The feed intake (F.I) and body weight (B.W) were recorded on day 7, 14, 21, 28 and 35 per pen.Feed conversion was calculated as feed to gain ratio.Livability was recorded daily and calculated as percent within the pen.

Carcass characteristics
At the end of trail feeding period, two birds close to mean body weight were selected from each replicate and slaughter.After skinning dressing percentage were recorded and giblets were collected and weight while shank and keel bone length were measured after removing meat.

Composition of thigh meat
Whole thigh meat were collect from every slaughter bird that were slaughtered at the end of feeding period and preserved in deep freeze at 4°C until further analysis.They were at room temperature and oven dried at 100 C 0 for 24h and ground it for proximate *Corresponding author.E-mail: zulqarnain@kmust.edu.cn.

Statistical analysis
The data obtained on growth performance; carcass characteristics and meat composition were analyzed for Analysis of Variance (ANOVA) technique under Completely Randomized Design (Steel et al., 1997).Level of significance was kept at P<0.05.Means were compared for significance of difference with Duncan's Multiple Test (Duncan, 1955).

Growth performance
The supplementation of OTM is a possible solution to fulfill the modern broiler trace minerals requirement by using the NRC (1994) recommendations.Dietary supplementation of organic trace minerals did not affect feed intake, body weight gain and Feed conversion during first and last week of trail, suggesting that ITM replacement with OTM did not affect broiler performance during starter and finisher phase (1-7 days, 29-35 days).However, during growing phase (8-28 days), as OTM supplemented diet level increase weight gain by in taking less feed and FCR was improved.In the finisher phase (29-35 days) no significant differences were observed in feed intake and weight gain among all treatments groups (Tables 2, 3 and 4).In this study, overall growth performance values were slightly lower than those already reported studies, because the present study conducted in august and September month during these month temperature and relative humidity is much higher in Pakistan, these unfavorable conditions on the period of present study may be caused to lower BWG which may worse overall growth performance.Mortality rate among different experimental groups was also recorded and shown in Table 3. Non-significant difference was observed among 6 treatments groups.However, highest mortality rate was observed in group which was fed inorganic trace mineral supplemented diet throughout trail period.Overall mortality was within the acceptable ranges.

Carcass characteristics
Non-significant difference was observed between different treatments groups with little bit better dressing percentage were observed when feeding diet supplemented with ITM level.Table 4 present data on carcass characteristic.Organic trace minerals supplemented diet was found to have effect on shank and keel length, however it was not significant.as ITM diet level increased at 35 days trail, The shank length various treatment groups was 5.48, 5.45, 5.44, 5.43,5.39 and 5.40 cm respectively, and keel length measurement was 14.04, 14.01, 13.98, 13.95, 13.93 and 13.92 cm, respectively.Overall, organic trace mineral has effect on shank and keel bone length growth.While, organic trace mineral supplementation has no effect on weight of liver, spleen, heart but organic trace minerals supplementation has improved gizzard (gm) weight than that of ITM supplemented diet (Table 5).
Table 6 shows the data on the variable presenting the chemical composition of thigh meat.Feeding OTM did not have any significant effect on DM, fat, ash, and water content in thigh meat.However, CP content was improved in the groups fed with OTM supplemented diets than those of ITM supplementation.

DISCUSSION
Growth performance and carcass characteristics are the main parameters which normally used to evaluate the broiler performance.Since last 70 years, the success of however, it is important to note that these negligible element are important for broiler enzymes system, metabolism, growth and reproduction (Berger and Cunha, 2006).
In this study, we evaluated the effect of replacing ITM with OTM on growth performance, carcass characteristics and meat composition of thigh meat.We observed non significance difference in growth performance parameters between different treatment groups during 1 st week of trial which are completely in line with previous reports (Bao et al., 2007).However, we found differences in production performance of various treatment groups, these result are consistent with a pervious observations (Xia et al. 2004;Abdallah et al. 2009;El-Hussein et al., 2012).Current study findings were supported in their subsequent investigation in which they reported that OTM supplementation according to NRC (1994) recommendations is reasonable for highly growing broilers due to their inherent better bioavailability (Fly et al., 1989).However, inorganic trace element does not fulfill modern broiler trace element requirements due to their less bioavailability and negative interaction (Du et al. 1996;Mondal et al., 2007).However during 5 th week nonsignificant difference was identified, these finding are in agreement with Bao and Choct (2009) and Smith et al. (1995) who reported that OTM efficacy decrease as birds age increased (Bao et al. 2009;Smith et al. 1995).
Current study observations about carcass characteristics parameters are in line with the finding of Lu et al. (2006) who reported that broiler intake diet supplemented with organic Mn had shown lower percentage of abdominal fat, further OTM supplemented diet had no significant effect on the weight of liver (g), heart (g), and spleen (g).Our result are completely in agreement with the studies of Bao andChoct (2007) (2009) and Zhao et al. (2010) who reported that organic trace mineral had no effect on dressing percentage and giblets weight.In the present study, organic trace minerals supplementation improved the growth of shake and keel bone length.Osama et al. (2012) reported that organic Zn, Cu, Mn has improved the Tibia weight and length.In 2009, a study was conducted on turkeys and researcher observed that organic trace minerals supplementation improved biochemical properties of bone (Ferket et al. 2009).Similar observation has been reported on equine in which improvement of bone growth has been observed in yearling feeding organic trace mineral supplemented diet than those fed inorganic trace mineral supplemented diet (Ott and Johnson. 2001).
Poultry nutritionist are conscious about organic trace minerals supplementation due to price phenomena, however, we found that organic trace mineral supplementation become inexpensive due increased weight gain with better feed efficiency.The observation of present study are completely in line with the studies conducted by Osman and Raga (2007) and Abdallah et al. (2009), Osama et al. (2012) and El-Hussein et al. (2012) who reported that broilers fed diet supplemented with organic trace minerals has improved profit by decreasing cost of production.
Proximate analysis of thigh meat after skinning indicate that OTM supplementation did not affect significantly on DM, ash and Moisture content, however, crude protein content was improved among OTM fed groups than that of ITM supplemented group.This higher content was may be due to OTM forming complexes with organic compounds which are more soluble and mobile to the cell membranes and easily absorbed (Kincaid, 1989;Nelson, 1988).

Conclusion
1) It is proved that OTM supplementation according to NRC (1994) recommendation could be fully satisfy high genetic broilers requirement.
2) Feeding broiler diet with organic trace mineral during growing phase is improved broiler growth performance.
3) Feeding the diet supplemented with organic trace mineral has improved broiler thigh meat quality and overall economic efficiency of flock.

Table 2 .
Average weekly feed intake.

Table 3 .
Average weekly weight gain.

Table 4 .
Average weekly feed conversion ratio.

Table 5 .
Carcass characteristics of meat.

Table 6 .
Proximate analysis of thigh meat.