Effect of different levels of l-carnitine and excess lysine-methionine on broiler performance, carcass characteristics, blood constituents, immunity and triiodothyronine hormone

The influence of dietary L-carnitine and lysine (Lys)-methionine (Met) levels on productive performance, haematology and triiodothyronine hormone levels of broilers was investigated. Dietary treatments included different L-carnitine (0, 50 and 100 mg/kg) and Lys-Met (0%, 10% and 20% over National Research Council (NRC) (1994) recommendation levels), under a 3 × 3 factorial design arrangement. From the findings, the body weight (BW) gain, feed intake and feed conversion ratio (FCR) of broilers were significantly (p < 0.05) influenced by dietary treatments in the different growing stages. Conversely, carcass yield and organs did not differ (p > 0.05) among treatments, whereas meat-cuts varied significantly when broilers were fed experimental diets. Moreover, the dietary inclusion of the highest levels of amino-acids (L-carnitine (100 mg/kg) and Lys-Met (+20%)) produced a reduction (p < 0.05) of blood uric acid, also leading to the highest triiodothyronine (T3) hormone levels. Based on the obtained results, it can be concluded that the combination of extra levels of L-carnitine associated with Lys-Met positively influenced the performance traits in broiler chickens.