Effect of in ovo injection of different nutrients and 36 h starvation after hatch on hatchability, blood metabolites, intestinal morphology and growth performance of broiler chicks

Many birds do not have access to feed until 48 h after hatching (27). In ovo injection technology is a practical means for safe introduction of nutrients into developing embryos, including amino acids, carbohydrates, vitamins, L-carnitine, and hormones which may benefit post-hatch growth and BW gain (19, 36). The objective of this study was to evaluate the effects of in ovo injection of amino acids and dextrose, on hatchability, growth performance, blood metabolites, immune organs and intestinal morphology of the broiler chicks.

The experiment was conducted in a completely randomized design with 5 treatments, 3 replicates of 16 fertile eggs from Ross 308 breeders (28 Week old). Treatments consisted of control (no injection) and injection of 0.7 ml of different nutrients into the amniotic sac of fertile eggs on 17.5th day of incubation including: distilled water (sham), amino acids, dextrin 10% and dextrin 20%. The injection point from the broad end of the egg which was disinfected with alcohol and then 0.7 ml of each solution was injected into the amnion, using a 23- gauge needle with depth of 25 mm. The holes were then sealed using commercial glue. Hatched chicks were fasted for 36 hours. Body weight, feed intake and feed conversion ratio were recorded weekly. On days 1 and 3, blood samples were collected from one chick per replicate to determine serum metabolites (glucose, triglyceride, cholesterol,high density lipoprotein (HDL) and low density lipoprotein (LDL)). On days 1, 3, 7, 14 and 42, one bird per replicate was slaughtered and the relative weight of the immune organs (bursa of Fabricius, spleen and thymus) was determined. On day 3, villus height, crypt depth and villus height to crypt depth ratio were also measured.

The results showed that in ovo injection of amino acids can led to heavier birth weight compared to sham and control treatments (P=0.05). Chicks hatched from control eggs (no injection) showed the lowest significant weight gain and feed intake. Different treatments had no significant effect on feed conversion ratio. Improved growth performance could be attributed to increase in glycogen stores during the prenatal period (39). Because the late-term embryo, orally consumes the amniotic fluid (comprised primarily of water and albumen protein) prior to piping, in ovo injection of dextrose, amino acids or albumin may help to overcome any nutrient deficiency that may limit embryonic growth. Thus, it was hypothesized that administration of carbohydrates to the amnion may improve the energy level of the broiler embryo and reduce internal energy consumption (proteins and lipids) during piping, thereby increasing chick BW (45). Glucose is the major energy source in living organisms. Maintenance of glucose homeostasis during few days pre and post hatch is a great challenge in the chick’s life. The frequent activity of embryos implies a large amount of energy consumption, and higher glucose demand for fuel (45, 46). Serum glucose level after hatch was significantly higher in treatment dextrin 20% compared to sham treatment (P