Effects of the in ovo administration of two vitamin D3 sources (vitamin D3 (D3) and 25-hydroxyvitamin D3 (25OHD3)) on the expression of D3 activity- and immunity-related genes in broilers subjected to a coccidiosis infection were investigated. At 18 d of incubation (doi), five in ovo injection treatments were administrated to live embryonated Ross 708 broiler hatching eggs: non-injected (1) and diluent-injected (2) controls, or diluent injection containing 2.4 μg of D3 (3) or 2.4 μg of 25OHD3 (4), or their combination (5). Birds in the in ovo-injected treatments were challenged at 14 d of age (doa) with a 20× dosage of a live coccidial vaccine. At 14 and 28 doa, the expression of eight immunity-related genes (IL-2, IL-6, IL-10, TLR-4, TLR-15, MyD88, TGF-β4, and IFN-γ) and four D3 activity-related genes (1α-hydroxylase, 25-hydroxylase, 24-hydroxylase, and VDR) in the jejunum of one bird in each treatment–replicate group were evaluated. No significant treatment effects were observed for any of the genes before challenge. However, at 2 weeks post-challenge, the expression of 1α-hydroxylase, TGF-β4, and IL-10 increased in birds that received 25OHD3 alone in comparison to all the other in ovo-injected treatment groups. Additionally, the expression of 24-hydroxylase and IL-6 decreased in birds that received 25OHD3 in comparison to those injected with diluent or D3 alone. It was concluded that the in ovo injection of 2.4 μg of 25OHD3 may improve the intestinal immunity as well as the activity of D3 in Ross 708 broilers subjected to a coccidiosis challenge.

Effects of the in ovo injection of various concentrations of L-ascorbic acid (L-AA) on the hatchability and retention levels of L-AA in the serum of broiler embryos were investigated. A total of 960 Ross 708 broilers hatching eggs were randomly divided into four treatment groups: non-injected control, saline-injected control, and saline containing either 12 or 25 mg of L-AA. At 18 days of incubation (doi), injected eggs received a 100 μL volume of sterile saline (0.85%) alone or containing one of the two L-AA levels. Percentage egg weight loss was also determined from 0 to 12 and 12 to 18 doi. Hatch residue analysis was conducted after candling to determine the staging of embryo mortality. At approximately 21 doi, hatchability of live embryonated eggs (HI) and hatchling body weight (BW) were determined. Blood samples were taken at 6 and 24 h after L-AA in ovo injection to determine serum L-AA concentrations. Serum L-AA concentrations, HI, and hatchling BW did not differ among all treatment groups. However, chicks in the non-injected group had a higher (p = 0.05) embryonic mortality at hatch in comparison to those in the 12 mg of L-AA in saline and saline alone treatment groups. These results suggest that the in ovo injection of high levels of L-AA (12 and 25 mg) does not negatively affect HI or serum concentrations of L-AA but has the potential to promote embryonic livability. Further research is needed to determine the retention time of L-AA in the other tissues of broilers, including the cornea of the eye, in response to different levels of supplemental L-AA.

The effects of injecting the Poulvac E. coli vaccine (PECV) into either the air cell (AC) or amnion (AM) at different dosages at 18 days of incubation (DOI) on Hy-Line W-36-layer embryo and hatchling development were investigated. Serial dilutions of the PECV in diluent provided either 6.5 × 104, 6.5 × 103, 6.5 × 102, or 6.5 × 101 CFU dosages of E. coli. A diluent only injection treatment was included as a control. A total of 19 live embryonated eggs in each of 10 treatment groups were represented on each of 16 replicate levels (3040 total) in the hatcher unit. At 19 DOI, swabs of the AM indicated that the 6.5 × 101 and 6.5 × 102 CFU dosages provided a 50% level of PECV presence, whereas the 6.5 × 103 and 6.5 × 104 CFU dosages provided a 100% level of PECV presence. Conversely, only the 6.5 × 103 and 6.5 × 104 CFU dosages provided a 50% level of PECV presence in the AC. At all E. coli dosage levels, injection in the AM led to higher percentages of live or dead embryos that failed to pip (PEIS) (p = 0.001) or complete hatch (PEPE) (p ≤ 0.001) and a lower percentage of live fully hatched chicks (HI) (p ≤ 0.001), when compared to those injected in the AC. Like HI, significantly lower percentages of female hatchlings were also observed at 22 DOI for the AM compared to the AC injection, for all dosages except for the 6.5 × 102 CFU dosage. However, at all the dosages above the 6.5 × 101 CFU dosage, the AM injection resulted in a lower mean hatchling body weight (p = 0.010) at 22 DOI. In conclusion, E. coli populations were more prevalent in the AM than in the AC after the injection of the PECV in those sites. Furthermore, the injection of the PECV in the AM at all E. coli dosages generally increased late embryo mortality and decreased hatchability and hatchling body weight in comparison to an AC injection. It is concluded that the negative impact of the in ovo administration of the PECV in the AM at 18 DOI on the hatch process is dose dependent. However, effects of an increase in AC dosages and a decrease in AM dosages should be further investigated.

Effects of the dietary and in ovo administration of L-ascorbic acid (L-AA) on the performance, plasma nitric oxide, and eye L-AA concentrations of Ross 708 broilers were investigated. At 17 days of incubation, live embryonated hatching eggs were randomly assigned to a non-injected or sham-injected (100 μL of saline) control group, or a group injected with either 12 or 25 mg of L-AA suspended in 100 μL of saline. Chicks received a commercial diet with or without 200 mg/kg of supplemental L-AA and were randomly assigned to each of 6 replicate floor pens in each in ovo injection-dietary treatment combination. Weekly live performance variables through 14 days of post hatch age (doa) and the eye weights in both sexes at 0, 7, and 14 doa were determined. At 0 and 14 doa, plasma nitric oxide levels and eye L-AA concentrations of one bird of each sex in each pen were determined. Dietary supplemental L-AA decreased feed intake and growth between 0 and 7 doa, but from 8 to 14 doa; all birds fed supplemental L-AA had a lower feed conversion ratio. At 14 doa, male chicks had higher eye L-AA concentrations and lower plasma nitric oxide levels when treated in ovo with 12 mg of L-AA. In conclusion, dietary L-AA may be used to improve feed conversion in the second week of broiler post hatch growth. However, the in ovo administration of 12 mg of L-AA can increase male eye L-AA concentrations and is effective in reducing their general inflammatory response.

The effects of in ovo injection of L-ascorbic acid (L-AA) on tissue L-AA concentrations, systemic inflammation, plasma mineral concentrations, and tracheal histomorphology of Ross 708 broilers subjected to elevated atmospheric ammonia (NH3) levels after hatch were investigated. The four in ovo treatments included non-injected (control), saline-injected (control), or saline containing 12 or 25 mg of L-AA. The in ovo treatments were applied at 17 days of incubation by injecting a 100 μL volume of each pre-specified treatment into the amnion. At hatch, 12 male chicks were randomly allocated to each of the 12 replicate battery cages belonging to each treatment group. The cages were arranged in a randomized complete block design within a common room. All birds were exposed to 50 ppm of NH3 at 35 days of posthatch age (doa), and the concentration of NH3 in the room was recorded every 20 s. At 0, 7, 14, 21, and 28 doa, one bird from each cage was arbitrarily selected and euthanized for determinations of liver and eye L-AA concentrations at 0, 7, 14, 21, 28 doa; plasma nitric oxide concentrations at 0, 14, 21, and 28 doa; and plasma calcium and trace mineral concentrations at 0 and 21 doa. Tracheal histomorphology evaluations were performed at 0, 21, and 28 doa. There were no significant treatment differences for plasma nitric oxide and mineral concentrations, and for liver and eye L-AA concentrations at each sampling timepoint. In ovo injection of either 12 or 25 mg of L-AA decreased tracheal attenuation incidence at 0 doa compared to the non-injected or saline-injected control groups. Furthermore, the percentage of mild tracheal inflammation scores was lower at 28 doa in response to the in ovo injection of 12 mg of L-AA compared to the non-injected or saline-injected control groups. These results indicate that in ovo injection of 12 mg of L-AA reduces tracheal inflammation in broilers subjected to elevated atmospheric NH3.