Comparison ofeffects of nettle and asparagus essential oil, antibiotic and probiotic on performance, intestinal histomorphometry and microflora in broiler chickens

Today, synthetic chemical compounds used to achieve these purpose, and one of these compounds are important antibiotics (Hong et al 2012). The use of antibiotics as feed additive in animal and poultry feeds is restricted or prohibited in some area of the world (Aroiee et al 2005). As a result, new commercial additives were examined as a nutritional strategy to improve growth and feed conversion ratios (Thomke and Elwinger 1998). Medicinal plants have effective ingredients. Adding them to the diet improves the performance of broiler chicks and the amount of these effective ingredients varies in different species. Nettle and asparagus can be a stimulant for growth and replaces antibiotics in broiler chicks and also stimulates and strengthens the immune system in broiler chickens (Safamehr et al 2012). This herbal plant has many properties, including: appetite, blood pressure regulator and enhancer of red blood cells (Hanif et al 2011, Motavalizadeh 2012). During a study it has been shown that asparagus can improves humoral and cellular immune responses and has antimicrobial effects (Tekade et al 2008). Therefore, the purpose of this study was to compare the effects of nettle and asparagus essential oils, antibiotic and probiotics on performance, microflora and gastrointestinal histomorphology in broiler chicks. Seven hundred unsexed 1-d-old chicks (Arian strain) were weighed and divided into 7 groups (pen) of 25 chickens in each replicate (4 replicates) in a completely randomized design (CRD). The experimental diets including: 1) basal diet (control), 2) basal diet containing 150 mg/kg protexin, 3) basal diet containing 150 mg/kg avilamycin, 4) basal diet containing 200 mg/kg asparagus essential oil, 5) basal diet containing 400 mg/kg asparagus essential oil, 6) basal diet containing 200 mg/kg nettle essential oil and 7) basal diet containing 400 mg/kg nettle essential oil. Body weight gain and feed intake were measured and the feed conversion ratio was also calculated. Birds were slaughtered to prepare specimens for the small intestinal histomorphology at the end of the period. In terms of anatomy, duodenum is from gizzard to the entrance of the bile duct, jejunum is from bile duct to the entrance of the meckel's diverticulum, and ileum is from meckel's diverticulum to the ileocecal junction(Wang et al 2015, Uni et al 2000, Xu et al 2003 and Laudadio et al 2012). For measuring the length of the villi and the depth of the crypt, samples at a length of 1 cm from the middle parts of the duodenum, jejunum and ileum sections were cut and fixed in10% formalin fixation solution (Wang et al 2015 and Laudadio et al 2012). At 42 days of age, eight birds were randomly selected from each treatment and were slaughtered to investigate intestinal microflora. The digestive system of birds from the ileum was removed and the two ends are tied and immediately frozen. From each replication, equal amounts (0.1%) of ileum contents were dissolved in the physiologic serum (sodium chloride 0.9%), and after serial dilution and for microbial counting on specific culture, they were incubated at a temperature of 37 °C for 48 hours (Jamroz et al 2003). The collected data were compared using SAS software version 9.1 (SAS 2005). Body weight gain was not affected by the treatments during 1-42 days, but the feed intake and feed conversion ratio were significantly affected by experimental treatments (P<0.05). The feed conversion ratio in the whole period was improved in treatments containing nettle essential oil and asparagus essential oil at 200 and 400 mg as compared with other treatments. Safamehr et al. (2012) with using 0.5%, 1%, 1.5%, and 2% of nettle found a significant effect on body weight gain. The total number of bacteria was significantly affected by the treatments (P<0.05), so the total number of bacteria in the treatment containing the nettle and asparagus essential oil was significantly lower than that of the control group (P<0.05). Also, the number of Lactobacillus was significantly influenced by experimental treatments (P<0.05). The number of E.coli was significantly affected by experimental treatments (P<0.05). Jamroz et al. (2003) reported that medicinal plant extracts (carvacrol and cinnamaldehyde) reduced number of intestinal E.coli bacteria of broilers compared with the control group. Herbal essential oils have a strong antimicrobial activity against E.coli, Salmonella and Clostridium perfringens bacteria, while increasing effect on the population of Lactobacillusand Bifidobacter bacteria (Mitsch et al 2004). Effects of experimental treatments on the villus height, crypt depth, and ratio of villus height to crypt depth in the duodenum, jejunum and ileum was significant (P<0.05). Garcia et al. (2007) reported that the use of herbal extracts and antibiotics did not have a significant effect on the villus height, but the highest villus height and crypt depth was observed in the treatment containing the plant extract. Growth stimulants such as probiotics and herbal extracts reduced the amount of pathogenic bacteria, then contributes to maintaining the health and growth of the intestinal tissue, by mechanisms such as enhancing the beneficial intestinal microflora, increasing the production of fatty acids, and reducing the intestinal pH. Antongiovanni et al. (2007) reported that as the highest growth and development of the intestine occurs in the first and second weeks of the bird's life, in order to obtain a better result, the study of tissue changes in the intestine could be better at seven and fourteen days of the bird's life. Based on improvement in performance, intestinal microflora and histomorphology of small intestine, the asparagus and nettle essential oils can be used as a suitable alternative to antibiotics growth promoters in Arian broiler diets.