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This experiment was conducted to investigate and compare the efficacy of different feed additives on performance, tibial dyschondroplasia (TD) incidence and tibia characteristics of male broilers fed low-calcium diets. A completely randomized design, with six treatments and five replicates of five chicks per each was used. Experimental treatments were: (i) Basal diet containing recommended level of calcium (0.9%) as control treatment (Ctrl), (ii) low-calcium (0.67%) diet without any additive (LC), (iii) low-calcium diet + probiotic (2 g/kg diet), (iv) low-calcium diet + prebiotic (2 g/kg diet), (v) low-calcium diet + synbiotic [mix of probiotic and prebiotic (each 2 g/kg diet)], (vi) low-calcium diet + organic acid (1.5 g/kg diet). Birds were reared in an open-sided house system under natural tropical condition until 21 days of age. Feeding with low-calcium diet negatively influenced broiler performance (body weight, body weight gain and feed conversion ratio) and tibia characteristics, whereas dietary inclusion of all feed additives had beneficial effects on above-mentioned parameters and helped the birds to overcome problems related to low-calcium diets. Different treatments had no effect on TD incidence.

Summary High environmental temperature has detrimental effects on the gastrointestinal tract of poultry. An experiment was conducted to determine the effect of acute heat stress on endogenous amino acid (EAA) flow in broiler chickens. A total of 90, day-old broiler chicks were housed in battery cages in an environmentally controlled chamber. Chicks were fed a nitrogen-free diet on day 42 following either no heat exposure (no-heat) or 2 weeks exposure to 35 ± 1 °C for 3 h from days 28 to 42 (2-week heat) or 1 week exposure to 35 ± 1 °C for 3 h from days 35 to 42 (1 week heat). The most abundant amino acid in the ileal flow was glutamic acid, followed by aspartic acid, serine and threonine in non-heat stressed group. The EAA flow in 1-week heat and 2-week heat birds were significantly (p