Comparative effects of in ovo versus subcutaneous administration of the Marek's disease vaccine and pre-placement holding time on the processing yield of Ross 708 broilers.

Effects of the in ovo (i.o.) or subcutaneous (s.c.) method of administration (moa) of the Marek's disease (MD) vaccine and 4 or 18 h pre-placement holding time (pht) on the processing yield of male broilers through 49 d of age (doa) were investigated. Ross 708 broiler hatching eggs (3,900) were either i.o.-vaccinated at 18 d of incubation or chicks from eggs that were not i.o.-vaccinated were s.c.-vaccinated at hatch. The i.o. injections (50 µL) were delivered by a commercial multi-egg injector and s.c. injections (200 µL) were delivered by an automatic pneumatic s.c. injector. The pht was imposed on chicks after vaccination. Sixteen birds were initially assigned to each of 15 replicate floor pens belonging to each of the moa and pht combination groups and were grown out through 48 doa. At 48 doa, 6 birds were randomly selected from each replicate pen and were weighed and fasted for 16 h before being processed. At 49 doa, whole carcass, fat pad, breast muscle, and tenders muscles weights were recorded. Whole carcass weight as a percentage of live BW, and fat pad, breast muscle, and tenders muscles weights as percentages of both live and whole carcass weights were calculated. Upon subjection of the data to a 2 × 2 factorial analysis, only a main effect due to moa was observed for tenders muscles weight as a percentage of live and whole carcass weights. Tenders muscles weight as a percentage of both live (P ≤ 0.010) and whole carcass (P ≤ 0.004) weight was higher in birds hatched from eggs that received i.o. rather than s.c. vaccinations. In conclusion, in comparison to s.c. vaccination, i.o. vaccination increased relative tenders weight yield, whether or not broilers were held for 4 or 18 h prior to placement. Therefore, with regard to broiler processing yield, i.o. and s.c. vaccinations were safe for the administration of the MD vaccine, with i.o. vaccination displaying a slight potential advantage.

Comparative effects of in ovo versus subcutaneous administration of the Marek's disease vaccine and pre-placement holding time on the post-hatch performance of Ross 708 broilers1,2,3.

Effects of 2 types of methods of administration (moa; in ovo or s.c.) of the Marek's disease (MD) vaccine and 4 and 18 h pre-placement holding times (pht) on the performance of male broilers through 48 d of age were investigated. Ross 708 broiler hatching eggs (3,900) were either in ovo-vaccinated at 18 d of incubation or chicks from eggs that were not in ovo-injected were vaccinated s.c. at hatch, and chicks from each moa group were held for one of the 2 pht. In ovo injections (50 µL) were delivered by a commercial multi-egg injector and s.c. injections (0.2 mL) were delivered by an automatic pneumatic s.c. injector. Sixteen birds were assigned to each of 15 replicate floor pens belonging to each of the 4 moa and pht combination groups. Mortality and BW gain were determined at weekly intervals, and feed consumption and conversion were determined in the zero to 14, 14 to 28, 28 to 42, and 42 to 48 d age intervals. No interactive effects between moa and pht were observed for any variable, and mortality was not significantly affected by moa or pht. The 14 to 28 d feed consumption and 14 to 21 d BW gain of s.c.-vaccinated birds were lower than that of in ovo-vaccinated birds, and the increase in pht from 4 to 18 h decreased feed consumption through 28 d post hatch and BW gain through 35 d post hatch. Overall, the performances of male Ross 708 broilers through 48 d of age in response to in ovo and s.c. injections of the MD vaccine were comparable, and delays in hatchling placement should be less that 18 h in duration. Furthermore, despite the decrease in BW gain through 35 d associated with the reduction in feed consumption through 28 d in response to the 14 h increase in pht, in ovo injection did not exacerbate the effect of the increase in pht.

Relationships of eggshell, air cell, and cloacal temperatures of embryonated broiler hatching eggs during incubation.

The relationships of eggshell, air cell, and embryo cloacal temperatures in Ross × Ross 708 broiler hatching eggs were determined. Twenty eggs were weighed and set on each of 3 tray levels of a single incubator. Eggshell temperature (EST) of the eggs were recorded once in the morning (AM) and afternoon (PM) between 0 and 19 d of incubation (DOI) using an infrared thermometer (IRT). All eggs were candled and a transponder was implanted in the air cell of eggs containing live embryos (12 per tray level) at 12 DOI. At 19 DOI, transponders were implanted in the cloaca of live embryos from those same eggs. Air cell temperature (ACT) and EST readings were recorded once in the AM and PM between 12 and 19 DOI, and ACT and cloaca temperature (CLT) readings were recorded every 6 h between 19 and 21 DOI. The EST and ACT readings between 13 and 19 DOI were positively correlated. However, their respective mean temperatures between 13 and 19 DOI differed. The EST and ACT were not significantly influenced by tray level. Nevertheless, a main effect due to location (eggshell vs. air cell), and an interaction between DOI and time of day (AM and PM) in the 13 to 19 DOI interval were observed. Furthermore, an interaction was observed between location (air cell and cloaca) and the 6 h sequential time periods in the 19 to 21 DOI interval. However, across the entire 19 to 21 DOI interval, mean ACT and CLT were not significantly different, and were positively correlated. These data suggest that ACT readings are higher than those of EST during the last half of incubation, and that between 13 and 19 DOI, ACT readings may have the potential for use as a minimally invasive method by which to more accurately estimate the true core body temperature of broiler embryos. The effects of this method on hatchability and post-hatch performance need determination to better establish its practicality.

Comparative effects of in ovo versus subcutaneous administration of the Marek's disease vaccine and pre-placement holding time on the early post-hatch quality of Ross × Ross 708 broiler chicks.

Effects of method of administration [moa; in ovo (i.o.) or s.c.] of the Marek's disease vaccine and pre-placement holding time (pht) on early post-hatch male broiler chick quality was investigated. Sixty-five Ross × Ross 708 broiler hatching eggs were randomly set in each of 15 replicate trays (blocks) belonging to each of 4 pre-assigned moa and pht treatment combinations (3,900 total eggs) in a single stage Jamesway incubator. Eggs that were i.o.-vaccinated received injections at 18 d of incubation and male chicks from eggs that were not i.o.-injected were vaccinated by s.c. injection at hatch. The i.o. injections (50 µL) were delivered by a commercial multi-egg injector and the s.c. injections (200 µL) were delivered by an automatic pneumatic s.c. injector. Male chicks from each moa group also were subjected to either a 4 or 18 h pht. At hatch and placement total and yolk-free BW; body length; body mass index; yolk sac weight; yolk-free body and yolk sac weights as percentages of total BW; and yolk-free body and yolk moisture concentrations were determined. Chick BW also was determined at 7 d of age. Hatchability of fertile eggs was not affected by i.o. injection. However, at hatch, body length was increased and body mass index was decreased in response to i.o. injection. No main effect of moa or an interactive effect with pht was observed for the above variables at placement. However, body length was longer and body mass was lower in the 18 h than in the 4 h pht chicks. Placement yolk sac and body weights, and the 7 d BW of 18 h pht chicks was also lower than that of 4 h pht chicks. In conclusion, prolonging pht for 14 h adversely affected early chick quality, whereas i.o. injection did not negatively affect the early post-hatch quality of Ross × Ross 708 broiler chicks whether or not they were held for 4 or 18 h prior to placement.

Effects of the in ovo injection of 25-hydroxycholecalciferol on the yolk and serum characteristics of male and female broiler embryos.

Serum concentrations of 25-hydroxycholecalciferol [25(OH)D3] in broiler embryos at 19 d of incubation:doi:have been shown to increase 3 times by the in ovo injection of 0.60 µg 25(OH)D3 on 18 doi. In this trial, effects of the injection of 25(OH)D3 at 18 doi on the yolks and sera of male and female Ross×Ross 708 broiler embryos were assessed. On 18 doi, embryonated eggs that were set in a single stage incubator were assigned to 6 replicate trays within each of 2 injection treatment groups. Treatments included those injected with 100 µL commercial diluent (control) and those injected with 0.60 µg 25(OH)D3 in 100 µL commercial diluent. On 19 doi, embryos and their yolk sacs were extracted for determination of sex, yolk weight, BW, serum CA and phosphorous concentrations, and yolk CA, phosphorous, moisture, dry matter, and lipid concentrations. The weight of female embryos with their attached yolk sacs as a percentage of set egg weight was greater than that of males (P=0.03). There were treatment×sex interactions for the weight of embryos with their attached yolk sacs relative to 19 doi egg weight (P=0.05) and for yolk CA concentration (P=0.004). In eggs that received 25(OH)D3, the weight of female embryos with their attached yolk sacs relative to 19 doi egg weight was higher than that of males (P=0.005), and percentage yolk CA was higher in control eggs containing female embryos in comparison to those containing males (P=0.007). An injection of 0.60 µg 25(OH)D3 at 18 doi eliminated yolk CA differences associated with embryo sex, suggesting that 25(OH)D3 may influence sex-related differences in the rate of yolk CA absorption by broiler embryos and may be related to subsequent sex-related differences in posthatch bone strength.

Effects of nicarbazin on the blood glucose and liver glycogen statuses of male broilers.

Nicarbazin (NCZ), an effective anticoccidial widely used by the global broiler industry, is known to produce some side effects in broilers. Recent field observations have suggested that NCZ could be associated with spiking mortality syndrome, a disease of uncertain etiology that is most commonly characterized by hypoglycemia. In turn, 2 trials were conducted to investigate the effects of NCZ on the blood glucose levels and liver glycogen content of Ross × Ross 708 male broilers. In 6 of 12 pens beginning at 1 d of age, NCZ was added to basal broiler diets at a rate of 125 mg/kg, and the other 6 pens were control pens in which birds received salinomycin instead of NCZ, at a rate of 66 mg/kg. Feed and water were provided ad libitum, feed was closely monitored in all pens to avoid shortages, no coccidial challenge was imposed, and room temperature never exceeded 29.4°C. At the end of the second trial, a photoperiod increase from 8L:16D to 24L:0D was imposed in an effort to induce stress due to feed engorgement. In response to NCZ in trial 1, 0 to 28 d feed conversion and relative liver weights on d 21 and 28 were higher, whereas 0 to 28 d cumulative BW gain was lower. In response to NCZ in trial 2, 0 to 13 d feed conversion was higher, whereas 0 to 13 d cumulative BW gain was lower. The added NCZ increased blood glucose on d 13 in trial 2, but did not affect at any time the liver constituents analyzed in both trials. In conclusion, the uninterrupted feeding of NCZ at 125 mg/kg in the starter and grower diets of male Ross × Ross 708 broilers increased feed conversion and reduced BW gain, but despite an increase in relative liver weight on d 21 and 28 posthatch, liver glucose and glycogen concentrations were not affected.

Dietary poultry fat, phytase, and 25-hydroxycholecalciferol influence the digestive and reproductive organ characteristics of commercial layers inoculated before or at the onset of lay with F-strain Mycoplasma gallisepticum.

Effects of 2 supplemental concentrations of dietary poultry fat (PF) and the combination of PF, phytase (PHY), and 25-hydroxycholecalciferol [25(OH)D] on the gross digestive and reproductive organ characteristics of commercial layers inoculated with F-strain Mycoplasma gallisepticum (FMG) were investigated in 2 trials. Sham and FMG inoculations were administered at 12 wk (before lay) or 22 wk (onset of lay), dietary treatments [basal control diet (BCD); BCD with 0.75% supplemental PF (LPFD); BCD with 1.50% supplemental PF (HPFD); HPFD additionally supplemented with 0.013% PHY and 0.025% 25(OH)D] were initiated at 20 wk of age, and organ characteristics were determined at 58 wk of age. In proportion to small intestine weight, jejuna were heavier in birds inoculated at 22 wk rather than at 12 wk of age. In hens inoculated at 22 wk of age, percentage of infundibulum weight was increased by FMG. The proportional length of infundibula in birds fed HPFD with PHY and 25(OH)D was longer than in those fed LPFD. In birds inoculated with FMG at 22 wk of age, BW was greater in those fed HPFD with or without added PHY and 25(OH)D in comparison with those fed LPFD, whereas LPFD increased percentage of oviduct and magnum weights when compared with the HPFD and BCD groups, respectively. Percentage of duodenum weight in birds that were fed HPFD with PHY and 25(OH)D was greater compared with those fed LPFD in the wk 22 sham and wk 12 FMG inoculation groups, but was also greater than in those fed BCD in the wk 12 FMG inoculation group. Conversely, percentage of duodenum weight was greater in birds fed LPFD compared with those fed HPFD after a wk 22 FMG inoculation. However, despite the effects of the supplemental combination of 1.50% PF, PHY, and 25(OH)D on the oviduct and small intestine structures, it did not result in a subsequent influence on layer performance, as indicated in a previous companion report.

Influence of supplemental dietary poultry fat, phytase, and 25-hydroxycholecalciferol on the egg characteristics of commercial layers inoculated before or at the onset of lay with F-strain Mycoplasma gallisepticum.

The effects of supplemental dietary poultry fat (PF), phytase (PHY), and 25-hydroxycholecalciferol (D3) on the egg characteristics of commercial layers inoculated with F-strain Mycoplasma gallisepticum (FMG) were investigated in 2 trials. Sham and FMG inoculations were administered at 12 (before lay) and 22 (onset of lay) wk and 4 dietary treatments [basal control diet (BCD); BCD with 0.75% supplemental PF; BCD with 1.50% supplemental PF; BCD with 1.50% supplemental PF, 0.013% PHY, and 0.025% D3] were initiated at 20 wk of age. Percentages of albumen, yolk, and eggshell weights; yolk:albumen ratio; yolk moisture and lipid concentrations; and eggshell weight per unit of surface area were determined at 24, 34, 44, 50, and 58 wk of age. Inoculation with FMG reduced yolk lipid concentration at wk 24 and increased yolk moisture concentration at wk 58. In birds inoculated on wk 22, percentage of yolk weight was lower in those inoculated with FMG compared with those that were sham-inoculated. Yolk:albumen ratio was lower in birds that were FMG-inoculated at 22 wk of age compared with those that were sham-inoculated at the same age or that were FMG-inoculated at 12 wk of age. Percentage of yolk weight was greater in birds inoculated at wk 22 and fed the BCD with 1.50% supplemental PF treatment compared with those inoculated at wk 22 and fed the BCD or BCD with 1.50% supplemental PF, 0.013% PHY, and 0.025% D3 treatments and compared with birds inoculated at wk 12 and fed the BCD with 0.75% supplemental PF treatment. In conclusion, inoculation with FMG before or at the onset of lay caused a decrease in yolk lipid content early in lay but an increase in yolk moisture late in lay, and FMG reduced percentage of yolk weight in birds inoculated on wk 22. Furthermore, when used in combination with added 1.50% PF in birds inoculated on wk 22, supplementary PHY and D3 prevented an increase in percentage of yolk weight that occurred in response to diets supplemented only with 1.50% PF.

Influence of supplemental dietary poultry fat, phytase, and 25-hydroxycholecalciferol on the performance of commercial layers inoculated before or at the onset of lay with F-strain Mycoplasma gallisepticum.

The effects of 2 levels of supplemental dietary poultry fat (PF) and the combination of PF, phytase (PHY), and 25-hydroxycholecalciferol (D(3)) on the performance of commercial layers inoculated with F-strain Mycoplasma gallisepticum (FMG) were investigated in 2 trials. Sham and FMG inoculations were administered at 12 (before lay) and 22 (early in lay) wk and dietary treatments [basal control diet (BCD), BCD with 0.75% supplemental PF, BCD with 1.50% supplemental PF, and BCD with 1.50% supplemental PF, 0.013% PHY, and 0.025% D(3)] were initiated at 20 wk of age. Hen BW, egg weight, and egg production (EP) were determined every 4 wk between 24 and 58 wk of age. Feed consumption (FC) and feed conversion were determined in 4-wk intervals beginning on wk 25 and ending on wk 58, and total mortality and mean EP were determined over the entire 24 to 58-wk period. The addition of 0.75 and 1.50% PF increased BW at wk 48 and 58, respectively, and supplemental PF at the 1.50% level increased the BW of hens that had been inoculated (sham or FMG) on wk 22 and reduced the FC of hens inoculated on wk 12. Feed conversion was decreased in the 25 to 28- and 57 to 58-wk age periods and increased in the 45 to 48-wk age periods by an FMG inoculation. In birds inoculated at 22 wk of age, FMG increased egg weight. Although EP was reduced at wk 24 and was increased at wk 58 by FMG, total EP was not affected. In conclusion, an inoculation of FMG at either 12 or 22 wk of age can result in a relative shift in EP from the early to late stage of lay without affecting total EP, and although the BW and FC responses of hens to added dietary PF were influenced by their age and the age of inoculation, use of the supplemental combination of PHY and D(3) had no additional effect on performance when provided in conjunction with 1.50% PF.

Influence of supplemental dietary poultry fat on the digestive and reproductive organ characteristics of commercial layers inoculated before or at the onset of lay with F-strain Mycoplasma gallisepticum.

Effects of F-strain Mycoplasma gallisepticum (FMG) inoculation and 1.5% supplemental dietary poultry fat (PF) on the digestive and reproductive organ characteristics of commercial layers at 58 wk of age were investigated. Sham and FMG inoculations were administered at 12 (before lay) and 22 (early in lay) wk of age, and dietary treatments (basal control diets and basal control diets with PF) were initiated at 20 wk of age. Supplemental PF increased BW and decreased isthmal length relative to total oviduct length in hens. Various oviduct segments were also affected by the type and age of inoculation, and these effects were further influenced by the use of PF. In comparison to their time-specific sham-inoculated controls, infundibulum weight relative to BW was increased when birds were inoculated with FMG at 22 wk, whereas isthmus weight relative to total oviduct weight was increased by FMG inoculation at 12 wk of age. However, PF affected infundibulum length relative to total oviduct length only in sham-inoculated birds, and PF increased magnum weight relative to total oviduct weight only in birds inoculated at 22 wk of age (sham or FMG). Furthermore, PF decreased isthmus weight relative to total oviduct weight only in birds that were sham-inoculated (12 or 22 wk). In conclusion, the inoculation of FMG at 12 or 22 wk may increase the relative contributions of the isthmus and infundibulum, respectively, to the total mass of the oviduct. In addition, PF may decrease the relative length of the isthmus and increase the relative weight of the magnum in the oviducts of birds that have been inoculated at 22 wk of age (sham or FMG). Previous studies have shown 1.5% supplemental dietary PF to influence feed consumption throughout lay and performance early in lay in hens that were inoculated with FMG at 12 wk of age. However, the current results suggest that these influences are associated with gross changes in the oviduct but not the digestive tract of layers.

Influence of supplemental dietary poultry fat on the yolk characteristics of commercial layers inoculated before or at the onset of lay with F-strain Mycoplasma gallisepticum.

Effects of F-strain Mycoplasma gallisepticum (FMG) inoculation and 1.5% supplemental dietary poultry fat (PF) on the egg yolk characteristics of commercial layers at 24, 34, 44, 50, and 58 wk of age were investigated. Sham and FMG inoculations were administered at 12 and 22 wk of age and dietary treatments (basal control and basal control with 1.5% supplemental PF) were initiated at 20 wk of age. Yolk lipid concentration was reduced on wk 24 in birds that had been inoculated at 12 or 22 wk of age with FMG. The use of 1.5% supplemental PF increased percentage of yolk weight and yolk:albumen ratio across age and inoculation treatment. At 58 wk of age, concentrations of yolk palmitic acid increased and those of oleic and linolenic acid decreased when sham inoculations were given at 22 rather than at 12 wk of age. However, FMG inoculations given at 22 rather than at 12 wk increased palmitoleic acid and decreased stearic acid yolk concentrations. At 12 wk of age, FMG inoculations decreased yolk palmitoleic, oleic, and linolenic acid concentrations while causing increased yolk stearic and arachidonic acid levels when compared with sham inoculations. Furthermore, 1.5% supplemental PF decreased concentrations of palmitic and oleic acid and increased those of linoleic acid in the yolk at 58 wk of age. Despite the interaction of 1.5% supplemental PF with the prelay inoculation of FMG on early (18 to 26 wk) layer performance noted in a previous report, the effects of a prelay FMG inoculation and 1.5% supplemental PF on the egg yolk characteristics examined in the current study were independent of each other. This suggests that 1.5% supplemental PF is not effective in modulating the effects of an FMG inoculation at 12 wk of age on hen egg yolk characteristics between 24 and 58 wk of age and that the combined effects of PF supplementation and FMG inoculation on performance do not influence egg yolk characteristics.

Influence of supplemental dietary poultry fat on the performance of commercial layers inoculated before or at the onset of lay with F-strain Mycoplasma gallisepticum.

The effects of F-strain Mycoplasma gallisepticum (FMG) inoculation and 1.5% supplemental dietary poultry fat (PF) on the performance of commercial layers between 20 and 58 wk of age were investigated. Sham and FMG inoculations were administered at 12 (before lay) and 22 (early in lay) wk and dietary treatments (basal control diets and basal control diets with 1.5% supplemental PF) were initiated at 20 wk of age. Mortality at wk 47 and 53 was greatest in birds inoculated with FMG at 22 wk. Feed consumption from 20 to 23 and from 52 to 55 wk of age was greater in birds that were inoculated with FMG (12 or 22 wk). However, feed consumption decreased in birds that were inoculated at 12 wk (sham or FMG) when 1.5% supplemental PF was added to the diet. Percentage of total egg production (EP) between 22 and 58 wk of age was highest in hens that were inoculated with FMG at 22 wk. Furthermore, weekly EP increased at wk 27 and 58 and decreased at wk 47 after birds had been inoculated with FMG (12 or 22 wk), and increased at 22 wk and decreased at 54 wk when inoculations (sham or FMG) were given at 22 wk. Egg weight was increased at wk 29, 31, 39, 40, 42, 44, 53, and 58 in birds that were inoculated with FMG (12 or 22 wk); however, there were no coherent treatment effects on eggshell quality. An FMG inoculation at 22 wk may promote total EP through 58 wk, whereas the inoculation of commercial layers with FMG (12 or 22 wk) may increase subsequent feed consumption during the early and late stages of EP and increase egg weight throughout lay. However, the supplementation of hen diets with 1.5% PF beginning at 20 wk of age may reduce subsequent feed consumption throughout lay in birds having experienced a prelay (12 wk) inoculation.

Effects of 6/85-strain Mycoplasma gallisepticum vaccination alone at ten weeks of age or in conjunction with F-strain Mycoplasma gallisepticum inoculation overlays at twenty-two or forty-five weeks of age on the reproductive and digestive organs of commercial egg-laying hens.

Two trials were conducted to determine the effects of a prelay 6/85-strain Mycoplasma gallisepticum (6/85MG) vaccination alone or in conjunction with time-specific F-strain M. gallisepticum (FMG) inoculation overlays on the gross reproductive and digestive organ characteristics of commercial egg-laying hens. In each trial, the following 4 treatments were applied: 1) sham vaccination at 10 wk of age; 2) vaccination of 6/85MG at 10 wk; 3) 6/85MG at 10 wk overlaid by FMG inoculation at 22 wk; and 4) 6/85MG at 10 wk overlaid by FMG at 45 wk. Two birds per isolation pen (experimental replicate unit) were necropsied at the end of both trials to observe the effects of treatment on liver weight, liver lipid and moisture concentrations, incidence of fatty liver hemorrhagic syndrome, ovary weight, mature ovarian follicle numbers, and the total and segmental weights, lengths, and histologies of the oviduct and small intestine. The applied treatments affected only liver moisture. Liver moisture content was greater in birds vaccinated with 6/85MG at 10 wk alone or in conjunction with FMG at 45 wk in comparison with sham vaccinated controls and birds that received a 6/85MG vaccination at 10 wk overlaid by an FMG inoculation at 22 wk. Prelay 6/85MG vaccinations may be a suitable substitute for prelay FMG inoculations, and FMG overlays during lay on prelay 6/85MG vaccinations may also provide continual protection against field-strain MG infections without eliciting any subsequent suppressive effects on performance, as noted in an earlier study.