Effects of in ovo feeding of arginine and breeder age on post-hatch performance and morphometry in broiler chickens

The objective of this study was to examine the effects of <italic>in ovo</italic> feeding of arginine (Arg) and breeder age on hatching performance and morphometry in broiler chickens. The experiment was performed using a completely randomized design in 2 × 2 factorial arrangements, consisting of 2 breeder ages (32 and 62 weeks) and 2 <italic>in ovo</italic> feeding treatments (0% and 1% Arg). A total of 200 fertile eggs were obtained from Indian River broiler breeder flocks at 32 and 62 weeks of age, with average fertile egg weights of 57.4 ± 0.7 g and 70.8 ± 0.6 g, respectively. Eggs were randomly distributed into 4 treatments, each having 5 replicates of 10 eggs. All eggs were incubated under standardized temperature and humidity conditions of 38.0 ± 0.2°C and 75.0 ± 3%, respectively. Upon hatching, 80 chicks were randomly assigned into the same 2 × 2 factorial arrangements comprising 5 replicates. Hatching performance parameters were evaluated immediately after hatching. On day 10 post-hatch, one chick per replicate with a body weight closet to the mean of each treatment group was selected for morphometric analysis, assessment of relative organ weight, and evaluation of liver characteristics. The findings revealed a significant interaction (<italic>p</italic> < 0.05) between <italic>in ovo</italic> feeding of Arg and breeder age for hatchability and relative proventriculus and intestine weights. Chicks in the Arg group exhibited significantly less (<italic>p</italic> < 0.05) relative liver and kidney weights than those in the non-injected group. With respect to the main effects of breeder age, egg weight, body weight, middle toe and tibia lengths, and liver and intestine weights were significantly greater (<italic>p</italic> < 0.05) in chicks from 62-week-old breeder hens than in those from 32-week-old breeder hens. In conclusion, <italic>in ovo</italic> feeding of Arg and breeder age affect both hatchability and organ development in broiler chickens. <italic>In ovo</italic> feeding of Arg may alleviate the age-associated reduction in hatchability and promote intestinal development in chicks from older breeder hens. These findings suggest that the efficacy of <italic>in ovo</italic> feeding of Arg is influenced by the maternal age of the breeder hens.