الملخص

This study aimed to evaluate the effect of supplementing different levels of guanidinoacetic acid (GAA) to plant protein-based diets on the overall productive indicators of broiler chickens under cold conditions. A total of 180 one-day-old Ross 308 chicks were distributed in a completely randomized design into six dietary treatments, with three replicates per treatment and 10 birds per replicate. The treatments included an animal protein-based control diet (T1), a plant protein-based control diet (T2), three plant protein-based diets supplemented with GAA at 900, 1200, and 1500 mg kg⁻¹ feed (T3, T4, and T5, respectively), and a plant protein-based diet supplemented with taurine at 600 mg kg⁻¹ feed (T6). Following a common 14-day pre-starter phase, the experimental diets were introduced from day 15 to day 42 under chronic ambient cold stress (19–26.5°C). The results showed that 1200 mg kg⁻¹ feed (T4) was the most distinct GAA level in the overall growth indicators, as it was statistically comparable with the plant control and taurine treatments and significantly superior to the animal protein-based control. The 900 mg kg⁻¹ feed level (T3) showed a clearer position in the production index, whereas the 900 and 1200 mg kg⁻¹ feed levels were associated with the lowest significant mortality group. The 1500 mg kg⁻¹ feed level did not provide a clear productive response. Physiologically, these findings reveal that under cold duress, optimal GAA inclusion (1200 mg kg⁻¹) effectively counteracts the cold-induced thermoregulatory energy drain by bolstering the intracellular phosphocreatine-creatine shuttle to maintain cellular ATP homeostasis, thereby minimizing the diversion of net energy away from skeletal muscle deposition. Consequently, supplementing plant protein-based diets with 1200 mg kg⁻¹ feed GAA acts as a metabolic safeguard during winter rearing periods, providing a suitable nutritional option to support growth indicators, mitigate cold-induced mortality, and may help reduce dependence on animal protein sources when their quality or stability is variable.