In ovo temperature manipulation influences post-hatch muscle growth in the turkey

1. The effect of manipulating egg incubation temperature for short periods on turkey muscle development was determined using the M. semitendinosus, a thigh muscle, as the model. 2. Experiment 1. Eggs were incubated at a control temperature of 37.5 degrees C. For a 4-d period of 0 to 4, 5 to 8, 9 to 12, 13 to 16, 17 to 20 or 21 to 24 embryonic days (ED) eggs were transferred to either 38.5 or 35.5 degrees C. A regime of 38.5 degrees C at 5 to 8 and 9 to 12 ED caused an increased myonuclei number and muscle fibre number, respectively. 3. Experiment 2. Eggs were incubated at a control temperature of 37.5 degrees C. At 5 to 8 ED eggs were transferred to 38.5 or 35.5 degrees C. Temperature-manipulated embryos showed a delay in differentiation (myogenin expression) of the semitendinosus muscle compared to controls. 4. Manipulating the incubation temperature for 4 d in early incubation alters muscle development in the turkey with no observation of deformities or reduction in hatchability. We speculate that this increase in temperature may result in an improved muscle growth in the post-hatch bird.     

CO2 stunning of broilers and turkey hens

Stunning of poultry is still not solved satisfactorily. This concerns the requirements of animal welfare, meat quality and working conditions in the lairage, stunning and debleeding area. In an investigation of combined CO2-/O2-stunning in a new gas stunning system stress reactions of the animals during the induction phase and stunning effectivity were recorded in 7,000 chicken and 3.825 turkeys. During the induction phase (here: chicken 41 sek./turkeys 25-65 sec.) the animals first staid calm and then showed beak-opening as a consequence of the breathing stimulating effect of CO2. As a further sign of the aversiveness against CO2 the animals showed head shaking and wing flapping. The used settings of gas concentrations and stunning time in the system investigated lead to a very deep stunning resp. Killing of the animals. Therefore the debleeding cut could be performed late (chicken 44-55 sec., turkeys 54-90 sec.) after leaving the system without animals regaining consciousness. The stunning of turkeys with a mixture of CO2 and oxygen is an improvement according to animal welfare requirements because unnecessary pain and suffering, happening very often with electrical stunning, can be avoided. As far as animal welfare in chicken stunning is concerned it must be evaluated if gas stunning means an improvement because stress during the till now relatively long induction phase must be put into relation with comparably lower stress caused by hanging upside down and a fast and safe working electrical stunning unit.     

Self-selection of dietary protein and energy by turkey breeder hens

1. An experiment was conducted to determine the effects of self-selection of dietary protein and energy by turkey hens on reproductive performance in a warm environment. 2. Dietary self-selection had no significant effect on egg production, egg weight, or body weight of turkey hens. 3. Fertility and hatchability of eggs produced by self-selecting hens were significantly reduced compared to eggs from control hens fed on a complete diet. 4. Protein intake was significantly reduced among self-selecting hens when compared to control hens fed on a complete diet (P less than or equal to 0.001). 5. Food and energy intake decreased as the ambient temperature increased. Nevertheless, protein intake of self-selecting hens increased over the course of egg production despite decreasing food intake. Therefore, self-selecting hens preferred a diet with a greater protein content (g protein/kg diet) in the last 10 weeks of egg production than during the first 10 weeks of egg production.     

Pulsatile secretion of prolactin in laying and incubating turkey hens

Incubation behavior in the turkey hen is associated with a large increase in prolactin secretion. Previous research using hourly sampling of incubating hens has shown that prolactin levels fluctuate widely throughout a 24-hr period, suggestive of pulsatile secretion. This study compared the prolactin secretory patterns of laying and incubating turkeys to determine if prolactin is secreted episodically and if the high prolactin levels characteristic of the incubating hen may result, at least in part, from a change in the amplitude or frequency of secretory pulses. Blood samples were collected from cannulated, unrestrained laying and incubating hens at 10-min intervals for up to 24 hr. Data were analyzed with the PULSAR program to determine baseline prolactin levels and to establish the magnitude, frequency, and duration of episodic secretory peaks. The results revealed that prolactin is secreted in a pulsatile pattern in both laying and incubating turkey hens. Incubating hens had ninefold higher mean and baseline plasma prolactin levels than laying hens. The prolactin pulses were of approximately 12-fold greater amplitude in incubating hens than in laying hens, but the duration and frequency of pulses were the same in both groups. Therefore, the high prolactin levels required for incubation do not appear to result from an increase in the frequency of lactotroph stimulation, but rather from an increase in the prolactin secretion rate.     

Photoperiod influences age at puberty of heifers

Two experiments were conducted to determine if exposure of prepubertal heifers to supplemental lighting hastens the onset of puberty. In Exp. 1, 16 heifers were paired according to birth date (April 21 to July 4) and assigned randomly to exposure to either 18 h light/d (L) or natural photoperiods (N) from 22 wk of age until puberty. Twenty-two heifers in Exp. 2, born between February 27 and March 31 and between May 3 and May 17, 1981, were exposed to L or N from 24 wk of age until March 23, 1982. In Exp. 2, animals were bred at all estrous periods until conception. Age at first ovulation and first estrus were less (P less than .01 for Exp. 1 and P less than .10 for Exp. 2) for L than N heifers. Average ages at first estrus were 318 (L) and 367 d (N) for Exp. 1 and 367 (L) and 394 d (N) for Exp. 2. Age at conception in Exp. 2 was similar for L (380 d) and N (396 d) groups. There were no significant differences between L and N heifers in changes in body weight for either experiment. There was a photoperiod X age interaction (P less than .06) for ovarian volume in Exp. 1 because the rate of ovarian growth was greater for L than N heifers. Concentrations of LH were not affected by photoperiod in Exp. 1 and not measured in Exp. 2. There were no significant changes in LH concentrations between 22 and 34 wk of age. When expressed relative to first ovulation, LH levels were highest at 7 and 2 wk before first ovulation. Concentrations of prolactin in Exp. 1 were not significantly affected by photoperiod. It was concluded that supplemental lighting after 22 or 24 wk of age reduced ages at first ovulation and first estrus in heifers born from February to July. These effects of photoperiod were accompanied by changes in ovarian development.     

Pneumonia of turkey breeder hens associated with Mycoplasma synoviae

Turkey breeder hens showed an increase in mortality beginning at 38 wk of age with no other clinical signs or changes in egg production. While no respiratory signs were observed in live turkeys, those that died consistently had gross lesions of pneumonia. Histopathology of lungs revealed serofibrinous bronchopneumonia, lymphofollicular reaction, and other features suggesting a bacterial etiology. However, except for incidental findings, bacteria were not visualized in the sections examined, and none were isolated in meaningful numbers on routine bacteriologic media. At 42 wk of age the flock showed serologic evidence of infection with Mycoplasma synoviae (MS), and MS was identified by both mycoplasma culture and polymerase chain reaction (PCR) procedures in samples from choanal clefts and tracheas. Results of lung histopathology and PCR tests were consistent with a diagnosis of pneumonia caused by MS.     

Breeder turkey hens seropositive and culture-negative for Mycoplasma synoviae.

Four flocks of clinically normal turkey breeder hens were shown to have suspect and positive Mycoplasma synoviae (MS) hemagglutination-inhibition (HI), enzyme-linked immunosorbent assay, and, in some cases, serum plate agglutination serology in the absence of MS isolation. In all cases, HI serology for Mycoplasma gallisepticum (MG) and M. meleagridis was negative. Acholeplasma laidlawii was isolated from some hens in each of these MS-seropositive culture-negative flocks. Immunoblotting was used to help determine if this positive MS serology was a result of cross-reactive antibodies to A. laidlawii or to some other Mycoplasma species. When sera from two of the flocks were reacted with MS antigen in immunoblotting, a strong and characteristic MS immunoblot profile was seen. Immunoblotting gave no evidence of a strong antibody response to A. laidlawii, M. iowae, or MG. This suggests the presence (or earlier presence) of MS in these flocks that is difficult to isolate by routine methods. Furthermore, this work shows that immunoblotting can be an important tool in the diagnosis of poultry diseases.     

Protein and energy self-selection by turkey hens: reproductive performance

1. The influence of protein and energy self-selection on the reproductive performance of turkey hens was investigated. Large White turkey hens were fed on either a complete diet (185 g CP/kg, 11.30 MJ ME/kg) or were provided with a choice between a high protein-low energy diet (348 g CP/kg, 7.74 MJ ME/kg) and a high energy-low protein diet (81 g CP/kg, 13.39 MJ ME/kg). 2. Egg production, egg weight, and the fertility and hatchability of eggs produced were not significantly affected by the dietary treatments (P greater than 0.05). 3. While energy intake was not significantly different between groups, protein consumption decreased by approximately 40% (P less than or equal to 0.001) among self-selecting hens compared to hens fed on the complete diet. This resulted in a 10% (P less than or equal to 0.05) reduction in the food intake in the self-selecting birds.     

Occurrence of pale soft exudative meat in mature turkey hens

1. Colour distribution of mature turkey hen breast meat was evaluated during the year in 7 commercial flocks (100 samples/flock) to assess the occurrence of the pale soft and exudative (PSE) problem. Evaluation was done on the processing line 24 h post mortem.

2. In addition, 10 selected samples/flock were analysed for pH, water holding capacity (WHC), and texture. The average L* value (lightness) was 48.9 with a variance of 15.3, skewness of 0.16, and kurtosis of 0.17. Minimum and maximum L* values recorded during die study were 37.7 and 58.5, respectively.

3. The pH ranged from 5.68 to 6.64 (mean 5.96), WHC ranged from 7 to 102% (mean 41%), and gel strength for the cooked samples ranged from 30 to 54 N (mean 44N).

4. Correlations between colour and WHC indicated die potential use of a fast colour measurement to identify PSE meat.

5. Breast muscle samples with L*s52 exhibited poor WHC. When this value was used as a cut off point for identifying PSE meat, die lowest incident observed was 5% and the highest was 40%.     

A novel delivery of oxytetracycline in turkey breeder hens.

A novel product (SQ12) for subcutaneous (SQ) injectable delivery of oxytetracycline (OTC) has been developed for use in livestock. SQ12 employs microfluidic spheres encasing OTC crystals, which allows for longer release of the OTC compared with other injectable antibiotics. The objectives of the study were to determine serum and tissue levels of SQ12 in turkey breeder hens to 14 days postinjection and to evaluate effects of SQ12 on reproductive status. Thirty photostimulated hens were housed in litter floor pens and provided with 14.5 hr of light per day in a curtain-sided facility. Six hens served as untreated controls. Twelve hens per treatment group received SQ injections in the neck with SQ12 at 11.4 (L dose group) or 22.7 mg/kg (H dose group) to assess low and high doses, respectively. Serum samples were obtained from each hen at predose and 6, 12, 24, 48, 72, 96, 168, 240, and 336 hr postinjection. All hens were euthanatized at 14 and 15 days postinjection. One-half of the hens in each treatment group were sampled (liver, lung, kidneys, and breast muscle) for tissue residue levels of OTC. The control group had no detectable OTC in serum or tissues at any sample collection time. There were no detectable serum levels of OTC in either treatment group prior to injection. The average serum concentrations of the L and H dose groups showed similar depletion curves although the H dose group was 42% higher at maximum concentration than the L group. Average tissue concentration of OTC for all tissues sampled from the H dose group was twice that of the L dose group. All tissue levels were below the OTC residue tolerance limit. SQ12 provided an extended source of OTC in serum of turkey breeder hens with no effect on reproductive status. SQ12 may provide for a novel treatment of bacterial infection in turkey breeder hens with longer lasting serum levels compared with other single injectable OTC products.     

Daily rhythm of prolactin and corticosterone in unrestrained, incubating turkey hens

Plasma concentrations of prolactin and corticosterone were determined in hourly samples collected over a 25-hr period from unrestrained turkey hens exhibiting incubation (broody) behavior. Hens were maintained in cages on a 14 hr light: 10 hr dark photoperiod. Mean plasma prolactin concentration increased significantly late in the dark period to reach maximum daily levels of 496 ng/ml at the start of the photophase. However, a well-defined daily rhythm in prolactin secretion was not evident. Plasma corticosterone concentration showed a significant daily rhythm characterized by a major secretory peak (7.14 ng/ml) in the middle of the light period and a smaller, less well-defined peak (4.11 ng/ml) during the dark period. Both prolactin and corticosterone secretion ranged widely throughout the day in individual hens in a manner suggestive of pulsatile hormone secretion. This study demonstrates that the extremely high prolactin concentrations characteristic of the incubating turkey hen reflect large, dynamic changes in plasma prolactin concentrations occurring throughout the photoperiod, rather than a constantly high level of prolactin secretion.     

Photoperiod influences the immune status of multiparous pregnant sows and their piglets

Manipulation of photoperiod may provide a noninvasive, easily implemented, effective method to improve immune status and enhance the efficiency of production. The objective of this study was to evaluate the impact of manipulation of photoperiod on endocrine and immune responses of pregnant sows and their offspring. At d 83 of gestation, sows were moved to gestation stalls and kept on a photoperiod of 12 h of light:12 h of dark until d 90, when sows were assigned to a long day (LD; 16 h of light/d) or a short day (SD; 8 h of light/d) treatment. During farrowing and lactation, one-half of the sows remained on their initial photoperiod (LD:LD or SD:SD), whereas one-half were switched to the opposite treatment (LD:SD or SD:LD). Blood samples were collected from sows at d 0, 7, 14, and 21 posttreatment, 24-h postfarrowing, and the end of lactation (approximately d 21 postfarrowing). Piglets were bled at 7 and 21 d of age for immune measures. Relative to sows on LD, sows on SD had greater concanavalin A- (P = 0.003) and lipopolysaccharide- (P = 0.02) induced proliferative responses at d 7 but reduced responses at d 14. Compared with SD, sows on LD had a greater (P < 0.05) percentage of neutrophils and fewer (P < 0.05) lymphocytes at d 7, resulting in a greater (P = 0.05) neutrophil:lymphocyte ratio. Neutrophil phagocytosis was greater at d 21 in sows kept on LD. Cortisol concentrations tended to be greatest (P = 0.10) in sows on SD:SD at 24-h postfarrowing and throughout lactation. At 7 d of age, piglets on LD:SD had greater (P = 0.001) total white blood cells (WBC) and plasma cortisol (P = 0.001) relative to those on the other photoperiod treatments. Plasma immunoglobulin G was less (P = 0.001) in piglets from sows kept on SD:LD compared with the other photoperiod treatments. Piglets from sows kept on LD:LD tended to have lower total WBC (P = 0.08) at 21 d of age. Piglets from sows kept on SD:SD had greater concanavalin A- (P < 0.001) and lipopolysaccharide-induced (P < or = 0.10) proliferation responses and cortisol (P = 0.05). Phagocytosis was greater (P < 0.003) in piglets from sows that were kept on LD:LD. Cortisol (P = 0.02), WBC (P = 0.003), and immunoglobulin G (P = 0.001) were all influenced by gestational photoperiod treatment. These data indicate that photoperiod influences the immune status and endocrine response of piglets from dams that have been kept on a defined photoperiod. We conclude that photoperiod effects on piglets may be programmed in utero and can last throughout lactation.     

Reproductive performance of turkey hens as influenced by hormone implants.

Large White turkey hens were implanted with silicone capsules containing either cholesterol (control), progesterone, 17-beta oestradiol (E2), oestrone (E1) or a combination of progesterone and E2. Egg production and fertility were measured. Blood samples were collected weekly for measurement of progesterone by radioimmunoassay. 2. Progesterone alone caused a several-fold increase in serum progesterone concentrations initially and significantly depressed egg production. Simultaneous administration of E2 significantly decreased progesterone concentration, but did not ameliorate the decrease in egg production. 3. There were significant positive correlations between serum progesterone concentration and egg production in control birds and those receiving E2 and E1. There was no significant correlation between progesterone concentration and fertility. 4. The results indicated that, within the physiological range, higher progesterone concentrations are associated with higher egg production. However, maintenance of constant progesterone concentrations throughout the reproductive season by means of implants was not achieved. Implants of E1 and E2 did not affect fecundity.     

Characteristics of oviposition patterns of turkey hens and the influence of different wavelengths of light

1. Characteristics of individual oviposition patterns of turkey breeder hens were determined for 160 d of photostimulation with fluorescent blue, green or red light and with incandescent light. 2. In all treatments most eggs were laid during the afternoon and evening. The maximum frequency occurred at 14.00 to 15.00 h (8 to 9 h after light onset); about 15% of all eggs were laid in the dark period. 3. The hourly oviposition distribution remained unchanged and was specific to individual hens throughout the study period. However, it was highly variable between hens, ranging from highly dispersed to tightly clustered. 4. The total number of clutches per hen did not differ between treatments and eggs were laid in relatively short clutches; 65% were of two eggs or fewer, 30% of three to 5 eggs and only 5% of 6 eggs or more. 5. The oviposition time of the first egg in a clutch was very variable; however, oviposition time became more clustered and uniform as the position of the egg in a clutch increased. 6. Mean time of lay, mean interval between eggs and total lag time were not influenced by light treatment. Mean interval was about 27 h for all eggs and was not influenced by clutch size. 7. Light quality at the intensity used in this study did not appear to play an important role in oviposition patterns of turkey hens.     

Vaccination of turkey breeder hens and toms for fowl cholera with CU strain

Unvaccinated laying breeder hens and semen-producing toms were susceptible to the CU strain of Pasteurella multocida and highly susceptible to a virulent strain of P. multocida. Laying breeders vaccinated with CU strain when environmental temperatures were low ceased egg production during the first week after vaccination and had 29% mortality, whereas those vaccinated when temperatures were moderate had only a 25% decrease in egg production and 17% mortality. Comparable nonlaying breeders vaccinated during moderate temperatures did not die. Although few semen-producing toms died postvaccination and the quantity and quality of semen was not affected, 21.7% developed torticollis. Laying breeders were protected against CU vaccine and challenge with virulent P. multocida if vaccinated every 4 weeks beginning when 7 weeks old. Potential breeders vaccinated before laying with combinations of 3 vaccinations via drinking water, wing-web puncture, or inoculation into the air spaces of the head through the auditory tube were protected against challenge after the onset of laying. However, vaccination via wing-web puncture at 25 weeks of age resulted in abscesses that failed to resolve. The combination of vaccinations most effective in protecting laying breeders was vaccination in the drinking water at 7 and 11 weeks and inoculation into the air spaces of the head at 15 weeks.