Assessing the Influence of Guanidinoacetic Acid on Growth Performance, Body Temperature, Blood Metabolites, and Intestinal Morphometry in Broilers: A Comparative Sex-Based Experiment.

It is well known that female and male broilers showcase variations in their growth performance, influenced by various physiological factors. This experiment aims to explore potential differences between female and male broilers concerning growth performance, body temperature, blood metabolites, carcass traits, and intestinal architecture in response to guanidinoacetic acid (GAA) supplementation. A total of 240 Ross 308 broiler chickens were arranged in a 3 × 2 factorial design and randomly allocated into 48 boxes, each containing 5 birds. The experiment comprised six treatments, with eight replicates per treatment. The main factors investigated were dietary GAA levels (0%, 0.06%, and 0.12%) and sex (male and female). Male broilers demonstrated superior body weight gain (BWG) and feed intake (FI) compared to females ( p < 0.05). GAA supplementation at 0.12% concentration notably improved BWG and reduced FI and feed conversion ratio (FCR) across experimental phases ( p < 0.05). However, interactions between sex and GAA were minimal except for reduced FI and FCR ( p < 0.05) in both sexes during early growth stages. Regardless of GAA treatment, the male birds exhibited more elevated shank and head temperatures than the females. Carcass traits were largely unaffected by GAA supplementation or sex, except for higher heart yield in the males. Serum metabolite levels were not different between treatment groups at 10 and 24 days of age, except for a higher level of serum creatinine at 10 days in the female birds with 0.06% GA supplementation ( p < 0.05). Intestinal morphology was significantly affected by GAA and sex, depending on the segment of intestine, in which GAA supplementation significantly increased villus height, crypt depth, villus width, surface area, and goblet cell count, while the males consistently exhibited higher values of these parameters than the females, and differences were observed between intestinal segments, especially in the ileum and duodenum, at different ages. In conclusion, the interactions between GAA and sex had minimal influences on growth performance indices. However, male broilers demonstrated a more pronounced response to GAA concerning ileal architecture. This study highlights the importance of supplementing broiler chicken diets with GAA for optimizing male broiler performance and intestinal function. The inclusion of GAA into broiler diets needs further study to reveal the underlying mechanisms driving these sex-specific responses and assess the long-term impacts of GAA supplementation on broiler health and productivity.