**8. Growth performance and meat quality**

*Advances in Poultry Nutrition Research*

sources use [1].

proteins [44], with a non-antagonism of CuO NP with Zn. Na et al. [45] suggested the possibility that CuO NP are absorbed through a different pathway that other Cu

Liver handles most of the absorbed nutrients and regulates their release into blood circulation for further distribution in different tissues or excretion. Hence, increased concentration in liver is a suitable indicator of retention status. The minerals supplemented in their NP forms increase their bioavailability and utilization efficiency [46]. Minerals supplemented in their nano-forms retained better in in vivo studies as compared to their inorganic salts [41, 47, 48]. Patra and Lalhriatpuii [1] extensively reviewed the retention of nano mineral supplementation in poultry and suggested that Ca, P, Zn, Cu, Se, Mn and Fe in their nanoforms are retained better than their inorganic counterpart. Owing to better bioavailablity, Ca and P supplementation as nanominerals reduces the quantity of supplementation, thus making the ration economic and environment friendly [1]. Sohair et al. [49] reported that the use of hydroxyapatite NP is economically efficient as compared to the control diets. Nano-Zn in lower dose could be a good substitution in mineral premix instead of ZnO, which tend to improve carcass characteristics and oxidative stability of chicken meat [50]. Hu et al. [51] studied the selenium retention from nano-Se and selenite origins in chickens by the intravenous or oral administration of the radio labeled 75Se and the in vivo ligated intestinal loop procedure, and reported higher nano-Se retention in the whole body and liver tissue compared to that of selenite, and intestinal transport of Se through ligated intestinal lumen loop to body was higher than that of selenite. Retention of Se is found to be influenced by the dietary Se source and concentration of Se supplemented as well. Reports suggests nano-Se supplementation to Guangxi Yellow broilers diet improved hepatic and muscle Se contents in a dose dependent manner up to a supplemental dose of 0.3 mg/kg [52], suggesting a relationship between nano-Se metabolism and liver function. Similar responses were also reported by Meng et al. [53] and Mohapatra et al. [54], where they obtained higher Se deposition efficiency in nano-Se supplementation groups than sodium selenite group, which also suggests better retention of nano-Se than that of sodium selenite as suggested by Zhang et al. [55]. Radwan et al. [56] observed higher Se content in eggs by nano-Se supplementation as compared to sodium selenite, most probably due to the faster transfer of nano-Se into the egg. A linear and quadratic increase in liver and muscle Se in a proportionally to the dietary nano-Se level, with a the peak value at 2.0 mg/kg of dietary nano-Se was reported; however, considering meat quality, immune function, oxidation resistance, 0.3 to 0.5 mg/kg was reported to be the optimum level of supplementation of nano-Se for broilers [57]. Supplemental nano-Cr picolinate at 0.5 and 3 mg/ kg of Cr increased Cr and Ca concentration in the liver and egg, and improved Zn and Mn retention in layer chickens [58]. Nano-Cr added at 0.4 mg/kg feed was found to increase the retention of Cr, Ca, P, Zn, and Fe in layers, increased the Cr and Zn concentration in plasma, liver, and eggshell; zinc in egg yolk; Ca in the liver and eggshell [59]. However, no increase in Cr content in the eggs and blood of Japanese quails was reported due to dietary addition of 0.2 to 0.8 mg/kg of nano-Cr [60]. Jankowski et al. [61] reported no effect of reducing Mn from 100 to 50 or 10 mg/kg either from NP-Mn2O3 or MnO on the growth performance or oxidation process in liver and breast muscles and increased Mn accumulation and reduced Zn and Cu accumulation in the liver, breast muscle and skin but increased intestinal absorption of Zn. Nano MnSO4 supplementation resulted in improvement of tibia

**7. Nano-mineral supplementation and mineral retention**

**66**

Most of the studies on poultry has emphasized on growth promoting effect as well as mineral retention due to supplementation of nanoforms of minerals (**Figure 2**). Studies have shown growth promoting effects by feeding nano-Zn [48, 50, 65, 66], nano-Se [52, 54, 67], nano-Ca [49, 68, 69] and nano-Ag [70]. Mohammadi et al. [71] observed improved growth performance in broilers supplemented with nano-Zn-methionine and nano-Zn-max at 80 mg/kg of diet; however, dietary nano-Zn sulphate reduced growth performance in broilers. Nano-Ag supplementation at 4 mg/kg caused an improved body weight gain and best feed conversion ratio in broiler [70]. Silver acting as an antimicrobial agent on intestinal harmful bacteria may improve gut health leading to better nutrient absorption, which was manifested by improved weight gain, feed intake and feed conversion ratio of broilers fed diets containing Ag NP [72]. Nano-Ca phosphate at 50% level of recommended supplementation resulted in improved body weight gain without altering feed conversion ratio, carcass characteristics and biochemical parameters similar to the 100% DCP supplemented group [73].

Supplementation of DCP NP has been reported to show better feed conversion ratio and body weight gain in poultry at 50% levels [68] and at 1.75, 1.31, and 0.88% levels [69] when compared to the control groups fed with larger DCP particles. Similar to DCP NP, hydroxyapatite NP also increased growth rate and feed intake in broilers at 2 to10% supplementation [49] without affecting the digestibility coefficient of other nutrients. However, Sohair et al. [49] observed that supplementation of 0.12% of calcium phosphate-NP instead of the conventional DCP at 2% resulted in better body weight gain, feed efficiency and economic efficiency

**Figure 2.** *Different beneficial biological effects of nano-minerals in poultry.* in broiler chickens. Mishra et al. [48] fed layer birds with extremely low levels of nano-Zn (1/500th of basal dose) and obtained similar growth promoting effect. Likewise, Ahmadi et al. [65] observed increased body weight gain, feed intake, and feed efficiency at 60 and 90 mg/kg diet of ZnO NP, but exhibited a lower performance in chickens at a dose of 120 mg/kg diet, whereas Fathi [66] reported lower feed efficiency in birds by supplementing nano-ZnO at 40 mg/kg. In contrast, feed intake, body weight gain, feed efficiency and, carcass traits were not affected due to supplementation of nano-ZnO at 25 and 50 mg/kg as well as ZnO at 100 mg/kg [50]. Nano-Zn at 80 mg/kg increased Zn, Ca and P levels, bone dimensions, weight, total ash along with higher liver and muscle Zn concentration [74]. Significantly lower fat and cholesterol content and better antioxidant status was obtained by supplementation of nano-Zn than inorganic Zn at 80 mg/kg [74]. Nano-ZnO increased mRNA expressions of insulin like growth factor-1 and growth hormone genes in broiler chickens compared to the inorganic or organic Zn [75].

Nano-Cr increased protein contents in thigh and breast muscles and lowered fat and cholesterol concentrations in thigh muscles. Chromium NP at 0.5 mg/kg diet improved breast and thigh muscle protein content, average daily gain and feed efficiency and lowered cholesterol and fat in thigh muscles of the broilers [76]. However, supplemental nano-Cr picolinate at 0.5 and 3 mg/kg [58] or 0.4 mg/kg [59] of Cr did not affect body weight, feed intake, feed efficiency, and egg production of layer birds. Supplementation of nano-Cr at 0.8 mg/kg diet was effective in reducing the negative effects of induced stress on meat quality of quail broilers, as evident from reduced malondialdehyde concentration in the thigh muscle and unaltered hematological parameters [77]. CuO NP was more efficient in increasing growth performance and immunity compared with the conventional sources of Cu [78]. As compared to the inorganic salts, supplementation of nano-Se improved the body weight gain and lowered the feed to gain ratio at doses up to 0.30 mg/kg diet, beyond which no beneficial effect was recorded [52, 54]. Se-yeast and nano-Se resulted in better growth performance than sodium selenite at 0.2 mg/kg Se [79]. Nano-Se supplementation reduced drip loss percentage without altering weight gain, feed intake, and feed conversion, meat color or immune organ index (thymus, bursa, and spleen) in broilers [57]. However, Se supplementation irrespective of its source (sodium selenite or nano-Se) increased daily weight gain and feed efficiency [67], though nano-Se proved to be more efficient. Improved weight gain and feed conversion due to supplementation of Fe NP (7 mg/kg) was possibly due to increased arginine in liver [80]. Dietary Fe sulfate NP resulted in highest jejunal villi width and surface area in broiler chickens at 21 and 42 days of age [81]. Overall, above studies that nano-minerals at reduced dose rates have potential to improve growth performance and the quality of meat compared with the conventional mineral sources.
