Environmental enrichment is the process of providing stimulating environments for zoo animals in order for them to demonstrate their species-typical behavior, to allow them exercise control or choice over their environment, and to enhance their well-being. We are aimed to provide the available knowledges about the animal enrichment programs for zoo animals through literature review. As the results, we reviewed the design of stimulating and naturalistic enclosures, the housing etc. Enrichment includes the design of stimulating and naturalistic enclosures, the housing of appropriate social groups in zoo, and the introduction of objects, sounds, smells or other stimuli in the animal’s environment. Conclusionally, environmental enrichment is just as critical to Zoo animal welfare as nutrition and veterinary medicine. At the zoos, enrichment will be an integral part of the daily care of the species in the collection.

Our previous study demonstrated that fermented four-herb combination (Ulgum, Yagmomil, Maesil and Bokbunja) with probiotics (Saccharomyces cerevisiae, Lactobacillus acidophilus, Bacillus subtilis) (hence, this additives was designated PFH) have immune enhancing and antibacterial effects in broiler chickens. The aims of the present study were to investigate the effects of PFH on growth performance and meat quality of broiler chickens. Twenty-day-old Ross broiler chickens were fed with or without PFH for 2 weeks. Body weight gain of the 2% PFH-fed group was significantly increased compared with those of the control group (*P<0.05). Moreover, body weight gain of the 1% PFH-fed group was also showed a increased tendency compared with the control group, although the difference was not significant (P=0.06). However, no significant difference in feed intake was observed among the groups. Feed conversion ratio of the 2% PFH-fed group was significantly decreased compared with those of the control group (*P <0.05). In addition, feed conversion ratio of the 1% PFH-fed group was also showed a slightly decreased tendency compared with the control group, although the difference was not significant (P=0.07). However, no significant differences in the proximate composition (moisture, crude fat, crude protein and crude ash) and the physico-chemical index (cooking loss, shearing force, water holding capacity and pH) were found among the groups. In addition, succulence, tending and flavor in meat of all 3 groups were also not different. Taken together, these findings suggest the possibility that PFH could be used as the alternative of antibiotic growth promoters by improving the performance of broiler chickens.