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Effects of the in ovo injection of vitamin D 3 (D 3 ) and 25-hydroxyvitamin D 3 (25OHD 3 ) 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 multiegg injector: 1) diluent (control); diluent containing either 2) 2.4 μg D 3 ; 3) 2.4 μg 25OHD 3 ; or 4) 2.4 μg D 3  + 2.4 μg 25OHD 3 . 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 1 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 25OHD 3 than in diluent or D 3 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 25OHD 3 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 25OHD 3 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., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Effects of the in ovo injection of vitamin D 3 (D 3 ) and 25-hydroxycholecalciferol (25OHD 3 ) on broiler embryo serum 25OHD 3 concentrations, hatchability, and hatchling somatic characteristics were determined. Eggs from a 35-wk-old commercial Ross 708 broiler breeder flock were set in a single-stage incubator with 11 treatments represented on each of 8 incubator tray levels (blocks). Each treatment group within a flat on each tray level contained 30 eggs. Control treatments were noninjected and diluent injected. Vitamin treatments were commercial diluent containing 0.6 μg D 3 , 0.6 μg 25OHD 3 , 0.6 μg D 3 + 0.6 μg 25OHD 3 , 1.2 μg D 3 , 1.2 μg 25OHD 3 , 1.2 μg D 3 + 1.2 μg 25OHD 3 , 2.4 μg D 3 , 2.4 μg 25OHD 3 , or 2.4 μg D 3 + 2.4 μg 25OHD 3 . At 432 h of incubation (hoi), 50-μL solution volumes were injected. Blood samples were collected at 462 hoi for serum 25OHD 3 analysis, and hatchability of injected live embryonated eggs (HI) was determined at 492 and 516 hoi. At 516 hoi, hatchling yolk-free BW and weights of the liver and yolk sac were determined. Percentage of yolk moisture and dry mater was calculated. At 492 and 516 hoi, HI did not differ between treatments. Embryos that received 1.2 μg or more of either vitamin D 3 source alone or in combination had higher serum 25OHD 3 concentrations than those that were injected with diluent alone or diluent containing 0.6 μg of D 3 . Hatchlings that received 1.2 or 2.4 μg of 25OHD 3 had higher percentage of yolk dry matter or lower percentage of yolk moisture levels than noninjected controls and those that received D 3 alone at any level. These results indicate that the in ovo injection of either vitamin D 3 source at levels equal to or higher than 1.2 μg resulted in serum 25OHD 3 concentrations that were higher than that of noninjected controls. In addition, the in ovo injection of 1.2 μg or higher of either vitamin D 3 source did not negatively affect broiler HI or chick quality., (Copyright © 2020. Published by Elsevier Inc.)

The effects of in ovo injected vitamin D 3 source on eggshell temperature (ET) and performance of broilers through 14 D of age (doa) were investigated. Eggs from a 35-wk-old commercial Ross 708 broiler breeder flock were set in a single-stage incubator with 4 treatments representing each of 12 incubator tray levels (blocks). At 432 h of incubation (hoi), noninjected and diluent-injected (50 μL) groups were control treatment groups. Vitamin treatments in the commercial diluent were as follows: 2.4 μg of vitamin D 3 (D 3 ) or 25-hydroxylcholecalciferol (25OHD 3 ). After injection, ET readings were recorded (435, 441, 453, 459, and 465 hoi) by infrared thermometry. Hatchability, hatchling BW, and percentage of male and female hatchlings were determined at 502 hoi. Equal numbers of male and female chicks were placed in each pen and grown out for 14 doa. On a per-pen basis, BW was recorded after hatching at day 7 and 14 doa, and BW gain, average daily BW gain, feed intake (FI), and feed conversion ratio (FCR) were calculated between 0 to 14 doa. The ET of eggs significantly fluctuated during the postinjection time period; however, the type of vitamin D 3  source injected did not affect ET. Nevertheless, the injection of 25OHD 3 resulted in a lower late embryo mortality than the diluent and D 3 injection treatments. In addition, birds that received 25OHD 3 had a lower FI and FCR than birds in all other treatments. In conclusion, the in ovo injection of 25OHD 3 has the potential to improve early posthatch broiler performance without affecting ET., (Copyright © 2019. Published by Elsevier Inc.)