Effect of dietary supplemental plant extracts on performance, carcass characteristics, digestive system development, intestinal microflora and some blood parameters of broiler chicks

The study was conducted to determine whether dietary supplemental plant extracts could have the potential as alternative growth promoters to antibiotics. One hundred and five, 1-day-old male broiler chicks (Ross 308) were used in the experiment. The animals were allocated into seven dietary treatments groups in a complete randomized design. The groups were as follow: 1. Control (basal diet), 2. Antibiotic (basal diet + 10 mg flavomycin/kg diet), 3. Yucca schidigera (Basal diet + 120 mg Yucca schidigera extract/kg diet) 4. Oreganum vulgare (Basal diet + 120 mg Oreganum vulgare esanstial oil/kg diet), 5. Thymus vulgaris (Basal diet + 120 mg Thymus vulgaris esantial oil/kg diet), 6. Syzigium aromaticum (Basal diet + 120 mg Syzygium aromaticum esantial oil/kg diet), 7. Zingiber officinale (Basal diet + 120 mg Zingiber officinale essential oil/kg diet). Each group was fed ad libitum its own diet for a period of 42 days. The data were analyzed using GLM procedure of SAS (1987). Antibiotics or plant extract supplementation did not influence (P>0.05) body weight gain, feed intake and feed conversion efficiency significantly; however, treatments groups achieved numerically higher performance values. The highest weigh gain was achieved with antibiotic or Z. officinale. The birds receiving Z. officinale also attained the highest carcass weight and abdominal fat weight. The results with respect to cholesterol, triglycerides and glucose showed that cholesterol concentration was not influenced (P>0.05) by dietary treatments, however, glucose concentration was elevated (P<0.05) by Z. officinale, while triglyceride concentration was increased (P<0.05) by Z. officinale and also S. aromaticum. Plant extracts used in the trials also affected weight and length of some part of digestive tract. Especially, supplementation of O. vulgare or Z. officinale or S. aromaticum reduced (P<0.05) total length of digestive tract but increased (P<0.05) weight of jejunum. The results also showed that supplemental Z. officinale increased (P<0.05) the number of lactic acid bacteria in the jejunum. It was concluded that dietary supplemental plant extracts, especially Z. officinale increased growth performance and number of beneficial bacteria. It could be speculated that Z. officinale could be of value to replace antibiotics which have been banned to use as growth promoter in animal feeds.