Table 2. Effects of dietary ZnO nanoparticles on total tract apparent digestibility (TTAD) of nutrients in weanling pigs
Item
Crude protein TTAD, % Gross energy TTAD, % Total dietary Zn, mg/kg Faecal Zn, mg/kg DM
ZnO (3000 mg/kg)
70.2 77.2 2584
10744 0
Nano-ZnO (mg/kg) 15
30 60
65.9 71.3 74.3 73.2 72.6 77.3 80.2 79.7 144 156 176 200 578 716 913 1043
jejunum and decreases diarrhoea incidence. Compared to each other, nano-ZnO (at 300 and 450 mg/kg) shows better growth performance compared to the conventional ZnO (3000 mg/kg). In the study of Milani et al. (2017) the results showed that
the ZnO nanoparticles at 60 mg/kg is not high enough to trigger a significantly better growth performance compared to ZnO at 3000 mg/ kg. However, the digestibility of nutrients (protein and energy), although not statistically significant, is numerically improved at levels as low as 15 mg/kg Nano-ZnO (Table 2).
2. Intestinal morphology
The effects of nano-ZnO on intestinal morphology of weaning pigs are shown in Figure 1 (Pei et al., 2019). Pathological damage to villi in the duodenum, jejunum, and ileum (results not shown) was alleviated by 450 mg/kg nano-ZnO and 3000 mg/kg ZnO. Supplementation of both 450 mg/kg nano-ZnO and 3000 mg/kg ZnOs increased the villus height of duodenum, jejunum, and ileum. An enhancement of the villi (V) to crypt (C) ratio of duodenum and jejunum was observed in nano-ZnO (450 mg/kg) compared to ZnO (3000 mg/kg). The results indicate that ZnO nanoparticles can stimulate mucosal growth and enhance epithelial cell regeneration resulting in a better developed intestinal tract. Hence, nano-ZnO may improve the surface area for absorption and utilisation of nutrients to enhance growth performance.
3. Microflora population and immune response
The effects of nano-ZnO (450 mg/kg) on microbial content of the large intestine in weaned piglets showed significant a decrease in the
population of E. coli, in the contents of cecum, rectum, and colon. The decreases compared to ZnO (3000 mg/kg) were more pronounced in the
colon. But the differences in abundance of Salmonella, Lactobacillus, and Bacillus bifidus were not significant compared to the diets without supplements of zinc. The serum immunity indices showed that supplementing nano- ZnO (450 mg/kg) in piglet diets (Pei et al., 2019) increases the blood
concentrations of immunoglobulin A and cytokines IL-6 and TNF- compared to ZnO 3000 mg/kg; these results imply that nano-ZnOs may exhibit an anti-inflammatory capacity by changing the serum concentration in antibodies. In a similar study, Li et al. (2016) also reported that nano-sized ZnO can increase serum IgG and enhance the immune response of weanling piglets.
Concluding remarks Nano-ZnO improves zinc absorption and reduces feacal zinc excretion compared to doses of conventional ZnO; there was reduced zinc excretion in faeces and urine of piglets supplemented with 450 mg/kg nano-ZnOs compared to 3000 mg/kg ZnO (55.41% and 46.24%, respectively). In addition, a concentration of nano-ZnO of 450 mg/kg improves weight gain, feed intake and ratio gain:feed better than the conventional 3000 mg/kg ZnO. Compared to conventional ZnO, low concentration dosage of nano-ZnO (450 mg/kg) can better alleviate diarrhoea, improve intestinal morphology, and reduce the abundance of E. coli in piglets, contributing to reduction in environmental damage. It is suggested (Animine, 2017) that before testing engineered nano-ZnO particles in animal diets, certain challenges will need to be addressed: product characterization with appropriate analytical methods, industrial scaling from laboratory samples, ADME (Absorption, Distribution, Metabolism, Excretion) and toxicity levels to animals, safety for workers and for the environment, and compliance with local regulations.
Figure 1. Villus height, crypt depth, and villus height/crypt depth (V/C) in duodenum and jejunum in weaned pigs. 3. Microflora population and immune response
C M Y CM MY CY CMY K
PAGE 22 NOVEMBER/DECEMBER 2019 FEED COMPOUNDER
Comment section is sponsored by Compound Feed Engineering Ltd
www.cfegroup.com
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