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.
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.
The current study was conducted to determine the possible effects of the in ovo administration of different dosages of L-ascorbic acid (AA) to broiler hatching eggs on hatchability and its potential for reducing the adverse effects of delayed placement.A total of 702 broiler hatching eggs was hand-injected at 17 d of incubation (DOI) with 100 μL of sterile saline (0.85%) alone or containing 0.5, 1.5, 4.5, or 13.5 mg AA. Hatchability was recorded every 5 h from 480 h to 505 hours. Results showed that AA injection did not affect embryo BW as percentage of set egg weight or yolk sac weight as percentage of embryo weight at 19.5 DOI. The hatching time of all embryos that received an AA in ovo injection was between 480 and 495 h of incubation, and significantly fewer embryos hatched before 480 h in comparison to non-injected controls. Hatchability (above 92% in all groups) was not significantly affected by injection treatment. However, fertile eggs injected with saline containing 4.5 mg AA had the highest hatchability. At 21 DOI, hatching BW as a percentage of set egg weight and yolk sac weight as a percentage of BW were numerically higher in AA injection groups. An in ovo injection of AA at a 13.5 mg/egg level resulted in a numerically higher BW as a percentage of set egg weight. The in ovo injection of AA did not reduce the adverse effects of a 48-hour posthatch pre-placement holding time on BW or on yolk sac absorption. Overall, in ovo injection of L-ascorbic acid (0.5 to 13.5 mg/egg) into fertile broiler hatching eggs at 17 DOI did not negatively affect hatchability or embryo development, and did not prevent the negative effects of a 48-hour posthatch holding time on BW and yolk sac absorption. The range of tolerance as well as the optimal dosage of in ovo-injected AA warrants future study.
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