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Biomedical subjects

D Smidt

Publications and source records attributed to D Smidt.

At least 19 recordsLinked to original sources
PubMed1997

[Maturational quality, adaptation reactions and clinical-chemical blood values in automatically milk-fed bred milk calves].

Calves of the dairy herd were used for this investigation. Body weight and growth rate were measured at 4, 6, 10, 12 and 13 weeks of life and venous blood acid base status, gas content, creatinine, urea, total protein, Ca, Mg, P, Na, K, Cl, Fe and catecholamine content at 15 days and at 90 days of age as well. Changes of blood values were analyzed in connection with growth performance and with the blood values of calves at 15 days of age testing the individually different degrees of adaptation and development.

Acid-Base Equilibrium↗
PubMed1996

[Thyroid hormones in dairy calves after birth and in the first days of life. Amplitude of variation, maternal-fetal relationships and reaction patterns specific to the individual].

Dairy calves and their dams from the dairy herd of the institute were used for this investigation. Calvings were watch carefully and jugular venous blood samples taken immediately after delivery from the cow and the calf and in the calf at 24 hours and at 48 hours of postnatal age as well were analyzed for T4, FT4, T3 and FT3 by luminescence enzyme immunoassay (LEIA). Higher thyroid values in calves than in their dams could be found increasing short after birth and reaching their highest level within 24 hours of postnatal life. The individual thyroid hormone values at birth and at 24 hours and at 48 hours of age are well correlated meaning the changes during the first days are specific for each calf. Strong correlation between the thyroid hormone values of the cows and those of the calves could be found. Mean values of thyroid hormones were significantly higher in female than in male calves all time but not different in the dams of these calves.

Aging↗
PubMed1995

[Adaptation reaction of dairy calves in the first days of life. Effects of type of delivery and individuality of the newborn].

Surveying a calving period of tethered dairy cows, newborn dairy calves of different breeds were investigated just after birth and at 24 hours and 48 hours of their postnatal life as well. Blood samples taken by venipuncture in calves were analyzed for acid-base-balance, hemoglobin, catecholamine and cortisol. Comparing the mean values of the newborns from calvings without assistance, with slight pulling and with heavy pulling, differences could be found only in the first hours of postnatal life between some of them without hemoglobin content of the blood that was of individually specificity and all the time lowest in calves delivered by heavy traction. Great scattering of and strong relationship between some of the measured values are assessed on the basis of constitutional features, maturity and adaptability of the calves.

Acclimatization↗
PubMed1995

[Clinical chemical and hematological blood values and adaptation reactions in suckling calves in the first weeks of life].

Suckler calves of the mother cow herd were used for this investigation. Body weight, growth rate and venous blood acid base status, gas content, creatinine, urea, lactate, total protein, albumin, Ca, Mg, Na, K and Cl were measured at 20, 60 and 90 days of postnatal life. Body weight and growth rate showed strong correlations with some blood values especially at 60 and 90 days of age meaning that adaptation is performed successful in some calves and incomplete in others. Disproportionate growth of body parts and the limited oxygen-carrying capacity below the oxygen needs of the tissues may cause the great lactate values in some calves of all age groups.

Acclimatization↗
PubMed1995

[Thyroid hormones in cesarean-delivered suckling calves after birth and in the first days of life--maternofetal relations and early postnatal adaptation reactions].

Caesarean section delivered suckler calves and their dams from the mother cow herd were used for this investigation. Jugular venous blood samples taken immediately after delivery from the cow and the calf and in the calf at 24 hours and at 48 hours of postnatal age as well were analyzed for T4, FT4, T3 and FT3 by luminescence enzyme immunoassay. Strong correlation between the thyroid hormone values of the cow and those of the calf could be found. Higher thyroid hormone values were measured in calves increasing further at 24 hours of age and then decreasing a little at 48 hours of age with higher values in female than in male calves. A strong correlation existed between T3 and heart rate of the calves.

Aging↗
PubMed1994

[Reactions of heifers in early pregnancy and their offspring delivered at term by cesarean section and in the first postpartum days in a cow-calf operation].

In 11 heifers originating from one mother cow herd and in their offspring delivered by cesarean section heart rate recordings were taken during their staying in the calving box and later on in group housing. Heart rate showed a rhythmicity in accordance with behavioural physiological reactions. The mean heart rate of a 24 hour period in an animal was different between and within the newborn and elder animals. The mean heart rate was increasing in the calves during the first days of their postnatal life and decreasing in the mother cows within some days after parturition. Blood samples taken repeatedly in 9 heifers via an indwelling catheter and in their offspring short after birth and at 24 and 48 hours by venipuncture as well were analysed for acid-base status, cortisol, noradrenaline, adrenaline, hemoglobin and lactate. Comparing the results with other investigations can be used for evaluating the strain of delivery by cesarean section for the young and the mother as well as revealing main influences on the reactions of the animals and their individual specificity.

Acid-Base Equilibrium↗
PubMed1994

[Heart rate frequency and constitutional features of high yielding dairy cows in intensively managed and environmentally protected pasture].

The heart rate measured continuously in grazing cows over 24 hours is significantly different during specific behavioural patterns of an animal and is influenced by the stage of pregnancy of the cow. Repeated measurements of blood urea, creatinine, total protein, albumin and glucose concentration in these animals permit conclusions about the changes of body weight and of the liver function and hormonal integration of energy substrate supply. Living on pasture during the summer period the cows showed the lowest hemoglobin content and hematocrit level of the blood, which increased when the animals were housed in autumn or when near the end of their final trimester of pregnancy. Important differences, especially in the blood values, were found between the groups and within the groups between younger and older cows.

Animal Feed↗
PubMed1994

[The hemoglobin concentration in the blood of dairy cattle of different breeds and their offspring during the peripartum period].

Blood samples taken repeatedly from dairy cows on pasture (50 Holstein-Friesian) and then from 181 cows and their newborn calves within 5 to 10 min after birth were used for measurement of haemoglobin content (Hb). Hb decreased with ongoing lactation and pregnancy, increased several weeks before parturition and reached its highest value shortly after birth. There was some individual, breed and age specificity of Hb in dairy cows. Assisted calvings using marked traction resulted in no difference in Hb values of the cows when compared to other calvings; whereas the calves' Hb values were smaller and the difference between calf Hb and cow Hb was greater. A strong correlation between Hb of the cow and Hb of the newborn calf and the difference Hb calf-Hb cow could be found.

Aging↗
PubMed1989

Behavior, episodic secretion of cortisol, and adrenocortical reactivity in bulls subjected to tethering.

To study the effect of individual housing on behavior and adrenocortical activity, eight bulls were moved to a novel housing environment and subjected to 5 weeks of tethering in individual stanchions with a concrete and partially slatted floor. During the first and fourth week, resting behavior and episodic cortisol secretion were analyzed over two 24-hr periods and compared to those of eight control bulls kept free on deep straw. In addition, in the fifth week adrenocortical reactivity after ACTH(1-24) stimulation was analyzed in all subjects. Resting behavior was markedly influenced by type of housing. Although duration of lying down over 24 hr was similar in tethered and control bulls, the number of periods of lying down was significantly reduced and the frequency of investigating the lying area prior to lying down was significantly increased in tethered bulls. In the first week of study, the cortisol secretory patterns of experimental and control bulls differed. The frequency of secretory episodes was significantly reduced, and the mean amplitude of the episodes increased, though not significantly in experimental compared with control bulls. After 4 weeks of tethering, however, the secretory pattern had returned to levels similar to those of control bulls. Despite this return of the basic cortisol secretion, adrenocortical reactivity after a high dosage of ACTH(1-24) was significantly reduced in tethered bulls. The results suggest that an adaptation to tethering at the brain-pituitary level does not occur, but that the return of the basal cortisol secretion could be due to changes at the adrenocortical level.

Adrenal Cortex↗
PubMed1989

Behavior and heart rate of heifers housed in tether stanchions without straw.

The effect of tether housing without straw was studied in eight heifers over a 12-week period. Resting behavior was recorded in the first and the twelfth week and heart rate (HR) in the twelfth week and compared to that of eight control heifers kept in a group on deep straw. Tethered heifers changed body position from standing to lying and vice versa significantly less often, and frequency of lying intention movements prior to lying down was significantly increased in tethered heifers. Correspondingly, latency between first intention movement and actually lying down was markedly increased in tethered heifers. HR was significantly higher in tethered heifers in all situations studied. During the lying procedure, HR increased in all animals so that the difference between the two groups remained unchanged. The biggest difference between groups was measured during the first lying intention, when HR was 125.2 +/- 9.4 in tethered heifers and 76.8 +/- 6.1 in controls. The results indicate that lying down in tether stanchions is aversive to the heifers and avoided as much as possible.

Animals↗
PubMed1989

[Physiologic reactions during the slaughter of cattle and sheep with and without stunning].

In a first trial the cortical activity of cattle and sheep was tested using only an electrocorticogram (ECoG). The results showed a shorter phase after sticking or the ritual slaughter cut respectively, until the ECoG disappears in stunned animals. However, considering the time between stunning and the cervical state, the interval until disappearance of the ECoG was prolonged in the stunned animals. The observed time differences, however, are only a tendency and not statistically confirmed. Insofar, concerning animal protection, the different slaughter methods could be regarded equivalent. A second trial was designed in a manner to allow a more exact interpretation of the ECoGs and was completed by measuring visually and somatosensorically evoked potentials. Additionally, in contrast to the first trial, only adult cattle were used here. The results revealed shorter intervals until disappearance of cortical activities when using captive-bolt stunning. Also the variance was much lower in this trial than after ritual slaughter. The mean of the time differences was relatively low (5.5 seconds). It was especially remarkable that after captivebolt stunning absolutely no evoked potentials could be registrated, whereas these potentials lasted for 77 seconds (somatosensorically evoked potentials) and 55 seconds respectively (visually evoked potentials) after the ritual slaughter cut. Thus, after ritual slaughter a nervous conduction was measured up to 126 seconds in the extreme cases. However, from the results obtained it can not be concluded whether or not pain sensitivity occurred in the animals.

Abattoirs↗
PubMed1988

[Stress, health and production in swine].

The "porcine stress syndrome" is a well established concept. Effects exerted on part of the meat type pig populations by their increased susceptibility to stress, resulting in meat quality defects, are meant by it. The problem of stress is rather a complex phenomenon. Stress is a part of daily life and can have negative as well as positive effects on performance and health, depending on its intensity and duration. These connections are discussed in the following paragraphs: 1. Definition of stress, and of stress-related reactions and possibilities of their assessment. 2. Stressors and their effects on the performance and health of pigs with regard to genetic dispositions. 3. Conclusions for the avoidance of stress effects in pig production.

Animals↗
PubMed1986

An approach to successful freezing of demi-embryos derived from day-7 bovine embryos.

The developmental capacity of frozen/thawed bisected embryos (n = 33) derived from day-7 bovine embryos was investigated and compared to ordinary embryos after freezing and thawing (n = 28) and to freshly bisected embryos (n = 19). The freezing and thawing protocol was identical for ordinary and demi-embryos. The percentage of intact embryos classified as excellent, good, or poor after thawing was 92.9 and 96.3% for ordinary and demi-embryos, respectively. Pregnancy rates of 53.8 (8 15 ), 46.2 (6 13 ), and 47.5% (9 19 ) were obtained when frozen/thawed ordinary embryos and frozen/thawed demi-embryos classified as excellent or good and sealed with an additional zona pellucida from hatched pig blastocysts or freshly bisected embryos were transferred. One pair of identical twins resulted from the transfer of frozen/thawed demi-embryos sealed with an additional zona pellucida. Transfer of four frozen/thawed demi-embryos without an additional zona pellucida led to one pregnancy. In contrast, demi-embryos derived from frozen/thawed ordinary embryos (n = 8) as well as frozen/thawed demi-embryos classified as poor (n = 6) did not result in any pregnancies although two halves were transferred per recipient. It is concluded that sealing the punctured zona pellucida improves the developmental capacity of frozen/thawed demi-embryos derived from day-7 bovine embryos, and freezing demi-embryos is more efficient compared to the splitting of frozen/thawed ordinary embryos.

Journal Article↗