In broilers challenged with coccidiosis, effects of in ovo vitamin D₃ (D₃) and 25-hydroxyvitamin D₃ (25OHD₃) administration on their inflammatory response and small intestine morphology were evaluated. At 18 d of incubation (doi), a 50 μL volume of the following 5 in ovo injection treatments was administrated: non-injected (1) and diluent injected (2) controls, or diluent injection containing 2.4 μg D₃ (3) or 2.4 μg 25OHD₃ (4), or their combination (5). Four male broilers were randomly allocated to each of eight isolated replicate wire-floored battery cages at hatch, and birds were challenged at 14 d of age (doa) with a 20x live coccidial vaccine dosage. One bird from each treatment–replicate (40 birds in each of 8 replicates per treatment) was bled at 14 and 28 doa in order to collect blood for the determination of plasma IL-1β and nitric oxide (NO) concentrations. The duodenum, jejunum, and ilium from those same birds were excised for measurement of villus length, crypt depth, villus length to crypt depth ratio (VCR), and villus surface area. In ovo injection of 2.4 μg of 25OHD₃ resulted in a reduction in plasma NO levels as compared to all other treatments at 28 doa. Additionally, duodenal VCR increased in response to the in ovo injection of 25OHD₃ when compared to the diluent, D₃ alone, and the D₃ + 25OHD₃ combination treatments at two weeks post-challenge (28 doa). Therefore, it can be concluded that 2.4 μg of 25OHD₃, when administrated in ovo at 18 doi, may be used to decrease the inflammatory reaction as well as to enhance the small intestine morphology of broilers during a coccidiosis challenge.

Effects of the in ovo-injection of vitamin D₃ (D₃) and 25-hydroxyvitamin D₃ (25OHD₃) on broiler performance, carcass characteristics, and woody breast myopathy (WBM) incidence were investigated. Live embryonated Ross 708 broiler hatching eggs (2,880) were randomly assigned to one of the following in ovo injection treatments: (1) diluent (50 μL); diluent (50 μL) containing either (2) 2.4 μg D₃; (3) 2.4 μg 25OHD₃; or (4) 2.4 μg D₃ + 2.4 μg 25OHD₃. Eggs were injected at 18 d of incubation (doi) using an Inovoject multiegg injector. At hatch, 18 male chicks were randomly placed in each of 6 replicate pens belonging to each in ovo injection and, dietary treatment combination. Birds were fed either a commercial diet or a diet restricted in calcium and phosphorous (ReCaP) content by 20% for the starter, grower and finisher dietary phases. Broiler performance was determined in each dietary phase and breast muscle yield was also determined at 14 and 40 d of age (doa). At 41 and 46 doa, birds were processed for determination of WBM, carcass weight, and the absolute and relative (% of carcass weight) weights of various carcass parts. Compared to birds fed the commercial diet, birds fed ReCaP diets experienced a reduction in performance from 14 to 40 doa, in breast meat yield at 41 and 46 doa, and in WBM at 41 and 46 doa. At 14 and 40 doa, breast meat yield in birds that received an in ovo injection of 25OHD₃ alone was higher compared to birds that received diluent alone or a combination of D₃ and 25OHD₃. Lower WBM incidence in ReCaP-fed birds was associated with a lower breast weight. An increase in breast meat yield in response to 25OHD₃ alone may be due to improved immunity and small intestine morphology. However, further study is needed to determine the aforementioned effects.

Effects of the in ovo injection of vitamin D₃ (D₃) and 25-hydroxyvitamin D₃ (25OHD₃) on the immunity and small intestine morphology of broilers fed calcium and phosphorus-restricted diets were investigated. At 18 d of incubation (doi), live embryonated Ross 708 broiler hatching eggs were in ovo-injected with a 50 μL solution of one of the following treatments using an Inovoject multi-egg injector: 1) diluent (control); diluent containing either 2) 2.4 μg D₃; 3) 2.4 μg 25OHD₃; or 4) 2.4 μg D₃ + 2.4 μg 25OHD₃. At hatch, 18 randomly selected male broilers belonging to one of the 4 in ovo injection treatments were placed in each of 12 floor pens and were fed either a commercial diet or a diet restricted by 20% in calcium and available phosphorus (ReCaP) content for the starter, grower and finisher dietary phases. Concentrations of plasma IgG and IgM at 14 d of age (doa) and α-1-acid glycoprotein at 40 doa were determined. Bursa, liver, spleen, duodenum, jejunum, and ileum weights were recorded at 7, 14, and 40 doa and small intestine histology was evaluated at 14 and 40 doa. Blood and organ samples were randomly collected from one bird in each of the 6 replicate pens within each of the 8 (4 in ovo x 2 dietary) treatment groups. Plasma IgG levels were higher in 25OHD₃ than in diluent or D₃ in ovo-injected birds. At 14 doa, a higher jejunal villus length (VL) to crypt depth (CD) ratio (RVC) was observed in birds that were in ovo-injected with 25OHD₃ alone as compared to all other in ovo injection treatments. At 40 doa, ileal VL increased and jejunal CD decreased in commercial diet-fed birds compared to ReCaP diet-fed birds. In conclusion, the in ovo injection of 25OHD₃ alone increased the immune response and improved the small intestine morphology and subsequent nutrient uptake of Ross 708 broilers. However, a ReCaP diet was observed to be detrimental to their small intestine morphology.

In the commercial egg industry, avian pathogenic Escherichia coli (APEC) can lead to significant economic loss. The Poulvac E. coli vaccine (PECV) is a commercially available attenuated live vaccine commonly applied via spray or drinking water to protect against losses associated with colibacillosis. The PECV has not been tested in layer hatching eggs using in ovo injection. Therefore, the purpose of this experiment was to determine the effects of injecting 50 μL of different doses of the PECV into Hy-Line W-36-layer hatching eggs on the hatchability and quality characteristics of hatchlings. At 18 d of incubation (DOI), treatments included 1 noninjected and 1 diluent-injected control. Furthermore, PECV treatments included a full dose (4.4 × 10⁸E. coli CFU) or serial dilutions of the full dose to produce 4.4 × 10⁶, 4.4 × 10⁴, or 4.4 × 10² CFU doses of E. coli. In ovo injections targeted the amnion. Percent hatchability of live embryonated eggs (HI), percent residue eggs, hatchling mortality, and female chick whole and yolk-free BW, relative yolk sac weight, and body length were among the variables examined. Treatment significantly (P < 0.0001) affected HI, with HI being highest in the control groups (97.3% in the noninjected and 94.2% in the diluent-injected), and with HI values being 89.0, 88.9, 84.4, and 71.2% in the 4.4 × 10², 4.4 × 10⁴, 4.4 × 10⁶, and 4.4 × 10⁸ CFU E. coli dose treatments, respectively. The percentage of live embryos that did not complete hatch but that pipped internally (P = 0.024) or externally (P < 0.0001) were significantly affected by treatment, with percentages being highest in the 4.4 × 10⁸ CFU treatment. Female chick body length was significantly (P < 0.0001) affected by treatment and was longer in both control groups and in the 1 × 10² CFU E. coli treatment in comparison to all other treatments. Yolk-free female chick BW was significantly (P = 0.034) affected by treatment and was lower in the 4.4 × 10⁶ CFU and 4.4 × 10⁸ CFU treatments when compared to the diluent-injected control group. An increase in the E. coli concentration administered in the amnion of embryonated layer hatching eggs at 18 DOI decreased hatch success and female chick yolk-free BW and body length.

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.