Effect of dietary energy concentration on the growth of slow-growing Korat chickens from 43 to 84 days old

The aim of this study was to estimate the effect of diets with different energy levels on the growth performance of slow-growing chickens (so-called Korat chicken (KRC)). The KRC is a cross between a male Thai native chicken (Leung Hang Khoa) and females from crosses among modern broiler and layer lines. The study was divided into two experimental periods when the birds were from 43 to 63 days old and 64 to 84 days old. Birds received feed and water ad libitum throughout the trial. In this study, 1200 mixed-sex KRC(624 and 576 chicks in phases 1 and 2, respectively) were distributed equally to four diets, which provided 2750, 2900, 3050 and 3200 kcal ME/kg. There were six replicate pens of each treatment. At both ages,increased energy content of the diet resulted in decreased feed intake (FI) and thus improved the feed conversion ratio (FCR). Weight gain was unaffected by the treatments. Using a broken-line analysis, dietary energy containing about 3200 kcal ME/kg was found to have the most beneficial effect on FCR during both periods. Thus, the optimal ME for KRC between 43 and 84 days old was 3200 kcal/kg.