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Biomedical subjects

V L Christensen

Publications and source records attributed to V L Christensen.

81 records · Page 5Linked to original sources
PubMed1982

Physiology of turkey embryos during pipping and hatching II. selected blood parameters.

Blood samples from turkey embryos taken at days 24 to 28 of incubation, a time of great embryonic mortality were analyzed for plasma calcium, magnesium, potassium, total plasma protein, lipid, and glucose concentrations. Plasma calcium increased significantly (P less than .05) until pipping, after which it declined until hatching. Plasma magnesium declined significantly (P less than .01) only at hatching. Potassium concentration declined significantly (P less than .01) as the hatched state approached. Plasma total protein concentration decreased until the onset of pipping, after which the concentration increased significantly (P less than .01) until hatching. Plasma total lipid concentrations decreased significant (P less than .01) during pipping, but the concentration remained constant while the poult emerged from the shell. Plasma glucose concentration increased significantly (P less than .01) prior to pipping and again at hatching.

Animals↗
PubMed1982

Physiology of turkey embryos during pipping and hatching. V. Plasma total calcium, magnesium concentrations, and total calcium to magnesium ratios.

Plasma total calcium to magnesium ratios were observed as an index of muscular activity during pipping and hatching of chick and poult embryos. No significant changes were observed in plasma calcium (Ca) or magnesium (Mg) concentrations, but the total Ca to Mg ratio increased significantly just prior to pipping. Lighting the incubator during the last 5 days of incubation in significantly increased plasma Ca and Ca:Mg ratios. Lighting also resulted in significantly better hatchability and less late embryonic mortality. An increased plasma Ca:Mg ratio may be a physiological mechanism to provide increased muscular activity for the embryo in breaking the shell and emerging from it.

Animals↗
PubMed1982

Physiology of turkey embryos during pipping and hatching. IV. Thyroid function in embryos from selected hens.

Embryos from turkey hens selected for high and low hatchability were blood sampled at 24, 25, 26, 27, and 28 days of incubation. The plasma was recovered and assayed for thyroxine (T4) and triiodothyronine (T3) to observe differences in plasma T3 and T4 concentrations relative to reduced hatchability. Plasma T3 did not differ significantly between the high and low hatchability groups, but plasma T4 concentrations were significantly greater during pipping at 26 and 27 days of incubation in the high hatchability group than in the low hatchability group. No differences were observed between the T3 and T4 ratios of the high and low hatchability groups. Oxygen consumption was significantly lower in the low hatchability group than in the high hatchability group. The data indicated that hypothyroidism may be a physiological factor limiting hatchability in domestic turkeys.

Animals↗
PubMed1981

Effect of insemination intervals on oviducal sperm storage in turkeys.

Filling and emptying of sperm storage sites of the turkey oviduct were studied using tandem inseminations with semen from bronze and white males. Fertility was better among hens inseminated at weekly intervals than those inseminated at biweekly intervals. The rate of gland filling and emptying was unaffected by weekly and biweekly insemination intervals. However, gland filling and emptying were affected when the birds were inseminated early in a reproductive cycle, and stratification of spermatozoa occurred within the sperm-host glands. Stratification may have occurred to a lesser degree late in the reproductive cycle. It is suggested that sperm storage glands fill and empty at the same rates early and late in a breeding cycle, but fewer glands contain spermatozoa in the latter part of the season, resulting in a decreased fertility.

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PubMed1977

Effect of time of day of insemination and the position of the egg in the oviduct on the fertility of turkeys.

Turkeys were inseminated at six different times of the day (1:00 p.m., 3:00 p.m., 5:00 p.m., 6:00 p.m., 9:00 p.m., and 12:00 a.m.) to determine the effect of time of day of insemination and the stage of egg formation on fertility. Significantly (P less than .01) lower fertility resulted from insemination at 1:00 p.m. than from inseminations thereafter. Significantly higher fertility resulted from 9:00 p.m. and 12:00 a.m. insemination than from preceding times. Highest fertility resulted when inseminations were performed 8 to 18 hours prior to oviposition whereas lowest fertility resulted from hens inseminated both in the last seven hours of shell deposition and during the approximate time of ovulation.

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PubMed1975

The effect of time of day of insemination and oviposition on the fertility of turkey hens.

Turkey hens were inseminated at five different times of the day to determine the effect of time of day of insemination and the stage of egg formation on fertility. Results showed that fertility resulting from the 6 p.m. insemination was significantly greater than at 8 a.m., 10 a.m., 1 p.m. or 3 p.m. Conversely, fertility was significantly lower at 1 p.m. than at the other four times. Fertility was significantly lower if hens were inseminated during the last 10 hours that the egg was in the uterus and during the approximate time of ovulation than during the other times of egg development.

Animals↗
PubMedDate not supplied

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.

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