The effects of in ovo injection of synbiotic on hatchability, chick quality, blood indices and performance of newly hatched chicks of Japanese Quail

The embryonic stage is the most critical and sensitive period in development of organisms especially the birds. In ovo injection is a good instrument for feeding the essential nutrients to growing embryo in birds. The in ovo application of nutrients provides the further benefits to the growth and development of the growing embryo. This experiment was conducted to investigate the effects of in ovo injection of synbiotic solution on hatchability, quality indices, weights and blood indices of one-day old chicks in Japanese quail.

Three hundred and seventy five quail eggs were allocated to five treatments of control (without injection), 2 ml injection of distilled water and injection of 1, 2 and 4 μg synbiotic solution. On day 8 of incubation, the eggs were randomly divided to five groups each containing 75 eggs. Injection was done on day 8 of incubation into the air sac of the eggs by insulin syringes. The injection site on the top of the eggs was sterilized by ethanol 70% and a small hole was made with needle of 27G. After injection, the holes were sealed by paraffin and returned to the incubator. At the end of day 17, the unhatched eggs were opened to identify the infertile eggs or dead embryos. On hatching day, two chicks were used to determination of chick quality. All the hatched birds were weighted. Then all the hatched chicks were reared up to day 35 of age in the separate pens (five replicates pen for each treatment). The performance factors (weight gain, feed intake and feed conversion ratio) were determined during the experimental week. Moreover, the carcass characteristics (carcass, thigh and breast) internal organs (liver, gizzard, intestine and heart) were determined at the end of the experiment (35 days of age). All the experimental data were introduced to SAS (9.1) in a completely randomized design with five treatments and five replicate each. The means were further separated using Tukey-Kramer multiple comparison test.

The results showed that in ovo injection had no effects on quality parameters of newly hatched chicks (P>0.05). Moreover, synbiotic injection to the quail eggs caused a decrease in hatchability (P<0.05). Furthermore, the synbiotic injection did not affect the weight of day old chicks (P>0.05). No effect of synbiotic injection was observed during weeks 1, 3, 4 and 5 (P>0.05). In week 2, injection of distilled water and synbiotic caused higher weight gain as compared to control (P<0.05) whereas there were no significant differences between the other treatments. Distillated water or synbiotic injection did not affect feed consumption during weeks 1 and 4 (P>0.05) but changed the feed intake during weeks 2, 3 and 5 (P<0.05). During week 2, 1 μg synbiotic injection increased the feed intake as compared to the other treatments whereas no significant differences were observed between the others during this week. During week 3, injection of 1 and 2 μg synbiotic caused the higher feed intake in comparison to other treatments and the highest feed intake belonged to the birds with 2 μg synbiotic injected eggs. In week 5, injection of 1 and 2 μg synbiotic caused a higher feed intake but only the effect of 2 μg synbiotic injection was significant (P<0.05). Moreover, no effects of in ovo injection of synbiotic were indicated for carcass characteristics (carcass, breast and thigh), internal organs (liver, heart, intestine and gizzard) and blood indices (urea, uric acid, glucose, triglyceride, creatinine and protein) (P>0.05). No significant differences were observed between the treatments for blood enzymes of alkaline phosphatase and aspartate aminotransferase (P>0.05).

According to the results of current experiment, synbiotic in ovo injection to quail eggs had no effects on weight and quality of one day old chicks but caused the lower hatchability. In ovo injection of 1 μg synbiotic to the air sac of the quail eggs improved the weight gain of hatched chicks after hatch but causes the higher feed intake and feed conversion ratio. Injection of higher synbiotic more than 2 μg to the air sac of quail eggs increases the feed intake and feed conversion ratio of quail chicks. Moreover, synbiotic injection did not affect carcass characteristics, internal organs, blood enzymes and indices of quails.