University of Tehran Press Journal of Veterinary Research 2008-2525 81 1 2026 03 21 Effects of Guanidinoacetic Acid on Sperm Characteristics of Older Roosters and Hatchability Rate in Broiler Breeder Flocks Effects of Guanidinoacetic Acid on Sperm Characteristics of Older Roosters and Hatchability Rate in Broiler Breeder Flocks 43 53 105937 10.22059/jvr.2025.393823.3503 FA Hoda Javaheri Barfourooshi Department of Animal Production Management, Animal Science Research Institute of Iran (ASRI), Agricultural Research Education and Extension Organization (AREEO), Karaj, Iran Akbar Yaghobfar Department of Poultry Nutrition Animal Science Research Institute (ASRI), Agricultural Research, Education, and Extension Organization (AREEO), Karaj, Iran Journal Article 2025 10 15 BACKGROUND: Physical decline in older roosters negatively affects their mating behavior and hatchability in broiler breeder flocks. Energy-producing compounds such as guanidinoacetic acid (GAA) may help address this issue. OBJECTIVES: This study aimed to evaluate the effects of different levels of GAA on sperm characteristics and testicular histology in older roosters, and hatchability rate in a broiler breeder flock. METHODS: A total of 144 hens and 18 roosters from a Ross 308 breeder flock were divided into three groups; one control group feeding based on the Ross 308 feeding guides, a treatment group receiving 1200 mg/kg of GAA (CreAmino), and a treatment group receiving 1600 mg/kg of CreAmino. Each group consisted of 48 hens and 8 roosters, with 6 replicates per treatment. Data were recorded done for 20 weeks, starting from week 41. The data included body weight, testicular weight, quantitative and qualitative sperm characteristics, serum concentrations of creatinine, nitric oxide, insulin, and testosterone, as well as histological testicular parameters and egg hatchability rates. RESULTS: No significant differences in sperm characteristics were found among the groups. However, both CreAmino treatment groups showed a significant increase in the number of spermatogonia, spermatocytes, spermatids, and Leydig cells, as well as an increase in the diameter of the seminiferous tubules and the thickness of the germinal epithelium, compared to the control group (P≤0.05). Serum keratin levels were significantly elevated in the CreAmino 1200 group during the second sampling period compared to the CreAmino 1600 and control groups (P≤0.05). Furthermore, serum nitric oxide concentrations were significantly higher in the CreAmino 1600 group during the second sampling period and in the control group during the third sampling period, compared to other two groups (P≤0.05). The hatchability rates were not significantly different among the groups. CONCLUSIONS: The use of 1200 mg CreAmino can improve both quantitative and qualitative sperm characteristics and histological parameters in older roosters. However, the treatment with GAA does not significantly affect hatchability rate in broiler breeder flocks. BACKGROUND: Physical decline in older roosters negatively affects their mating behavior and hatchability in broiler breeder flocks. Energy-producing compounds such as guanidinoacetic acid (GAA) may help address this issue. OBJECTIVES: This study aimed to evaluate the effects of different levels of GAA on sperm characteristics and testicular histology in older roosters, and hatchability rate in a broiler breeder flock. METHODS: A total of 144 hens and 18 roosters from a Ross 308 breeder flock were divided into three groups; one control group feeding based on the Ross 308 feeding guides, a treatment group receiving 1200 mg/kg of GAA (CreAmino), and a treatment group receiving 1600 mg/kg of CreAmino. Each group consisted of 48 hens and 8 roosters, with 6 replicates per treatment. Data were recorded done for 20 weeks, starting from week 41. The data included body weight, testicular weight, quantitative and qualitative sperm characteristics, serum concentrations of creatinine, nitric oxide, insulin, and testosterone, as well as histological testicular parameters and egg hatchability rates. RESULTS: No significant differences in sperm characteristics were found among the groups. However, both CreAmino treatment groups showed a significant increase in the number of spermatogonia, spermatocytes, spermatids, and Leydig cells, as well as an increase in the diameter of the seminiferous tubules and the thickness of the germinal epithelium, compared to the control group (P≤0.05). Serum keratin levels were significantly elevated in the CreAmino 1200 group during the second sampling period compared to the CreAmino 1600 and control groups (P≤0.05). Furthermore, serum nitric oxide concentrations were significantly higher in the CreAmino 1600 group during the second sampling period and in the control group during the third sampling period, compared to other two groups (P≤0.05). The hatchability rates were not significantly different among the groups. CONCLUSIONS: The use of 1200 mg CreAmino can improve both quantitative and qualitative sperm characteristics and histological parameters in older roosters. However, the treatment with GAA does not significantly affect hatchability rate in broiler breeder flocks.

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