Biomedical subjects
Publications and source records attributed to W Holtz.
Rainbow trout semen cryopreserved 0.33, 5, 60 and 360 min after collection gave postthaw fertilization rates of 71.9, 68.4, 65.5 and 49.1% of eyed eggs, respectively. The corresponding result obtained with chilled semen stored for 2 wk under oxygen was 96.9%. This suggests that the freezing of rainbow trout semen should be done immediately after collection.
Cloprostenol was deposited in the vaginal lumen of sows on Day 111 of pregnancy at dosages of 100, 125 or 175 g and volumes of 1, 2 or 5 ml, respectively. A control group was treated with physiological saline. In 92 out of 93 prostaglandin-treated sows, parturition commenced approximately 22 h after application, with no significant differences between dose levels or volumes. There were also no differences in the average size and weight of litters born, weaning weight, frequency of postpartum complications or post-weaning fertility. Intravaginal application of cloprostenol is thus a simple and efficient means of inducing parturition in sows.
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Two prostaglandins, Estrumate and Dinolytic, and two progestagens, PRID and Norgestomet were compared for their effectiveness in controlling estrus in dairy cows. A total of 636 animals on 62 different farms in southern Lower Saxony/FRG were used in this study. After treatment with one of the four drugs a double fixed time insemination was always performed at 24-hour intervals. Later, an additional untreated animal was assigned to each group of four. The conception rate in the 734 cows which were inseminated and evaluated under standardized experimental conditions were ES, 51.0%; DY, 46.0%; PRID, 44.5%; NOR, 34.7% and untreated animals, 46.9%. When only those cows which had already calved were considered, the rates were 48.0%, 44.6%, 46.9%, 31.9% and 59.1% respectively. The time of treatment post-partum proved to be significant for the non-return rate 90 (P < 0.01) and the conception rate (P < 0.05). Treatment influenced the estrus cycle in all of the cows. Abnormal cycle length following treatment was observed in 50.7%, 52.0%, 41.6% and 52.8% of the cows in each group as compared to 12.1% in the untreated animals. After the third insemination at least 90% of the cows in each group had conceived. The effect of the various farms proved to be significant with regard to the insemination index (P < 0.01), NRR 90 (P < 0.05) and the conception rate (P < 0.05). All four drugs established their suitability for use under field conditions. Still, modifications in the treatment methods and the insemination regimen could lead to higher fertilization rates.
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The purpose of this experiment was to compare a range of oxytocin doses in order to find the most suitable dose to improve predictability and precision of timing of PGF-induced parturition in sows. Sows randomly allotted to 6 groups - group size varying between 28 and 39 - were either untreated controls (group 1) or received an IM injection of 2 mg of the PGF-analog Alfaprostol (Vetem) on day 111 of pregnancy (day 0 = last day of standing heat), followed 20 h later by 0, 5, 10, 20 or 30 IU oxytocin, respectively (groups 2 - 6). Both length and variability of the time from injection of oxytocin to the onset of parturition decreased with increasing dose. The response was faster and more predictable with older sows than with first litter gilts. A disadvantage of higher doses of oxytocin was the necessity of manual aid (11 % in controls, 52 % with the maximum level of 30 IU oxytocin). Litter size, weight and percentage of piglets weaned and time from weaning to subsequent estrus were not affected by any of the treatments. An oxytocin dose of 20 IU applied 20 h after PGF appeared to give the most effective response, although this will occasionally necessitate manual assistance with parturition.
Recovery rate and embryo quality were investigated in beef heifers and suckled cows following superovulation induced by 2000 IU pregnant mare serum (PMSG) combined with different methods of estrus cycle synchronization (Norgestomet, Prid, Dinolytic, Norgestomet combined with Dinolytic). Genital tracts were flushed upon slaughter with Dulbecco's medium 6.5 to 7.5 days after insemination. Of the heifers, 42 out of 43 responded to treatment. The mean embryo recovery rate, based on the number of corpora lutea, was only 14.8%. Of the 83 embryos recovered, 54.2% had developed to the expected stage and only 40% appeared normal. Of the adult cows, 55 out 58 responded with an embryo recovery rate of 39.5%. Of the 149 embryos recovered, 48.9% had developed to the expected stage and 67.1% of these appeared normal. In both heifers and adult cows, the different methods of estrus synchronization produced no significant differences in recovery rate or embryo quality.
Intramuscular injection of long-acting ACTH (10 micrograms/kg body weight) into male pigs, fitted with permanently indwelling jugular catheters, resulted in a significant rise of plasma corticosteroid concentrations for a period of between 0.5 and 20 hours after injection. Plasma testosterone levels were significantly increased between 60 and 120 min after ACTH administration. Between 6 and 12 hours after ACTH application, however, they were significantly depressed, evidencing a two phase effect of ACTH on testosterone levels. Plasma LH concentrations showed a slight but progressive decrease which was significant between 2.5 and 12 hours p.i. From these results it has been concluded that long-acting ACTH stimulates testosterone release. Because LH levels were depressed, they cannot have been responsible for the increase in plasma testosterone. The increase of plasma testosterone concentrations was not accompanied by a change of plasma prolactin levels.
Two trials were conducted to increase the effectiveness of parturition induction with PG analogs. In trial 1, 39 sows were treated with the analog Luprostiol (Pronilen, Vemie/Kempen). Of these, 19 received an additional injection of 30 i.u. oxytocin 24 h later. In trial 2, 126 sows were divided into four groups, three of which were treated with the analog Alfaprostol (Vetem/Milano), while one served as control. Two of the PG-treated groups received an additional oxytocin injection either 24 or 20 h later, respectively. The response to either of the PG analogs resembled that observed during earlier studies although the percentage of sows responding was somewhat lower (70% and 77%, respectively). Oxytocin increased the number of respondents to 84 and 89%, respectively, and parturition commenced promptly. In trial 1, parturition started within 2.1+/-1.6 (0 to 5) h after oxytocin, in trial 2 within 1.57+/-1.06 (0.5 to 3) h when the interval between prostaglandin and oxytocin was 24 h, and 1.81+/-0.84 (0.5 to 3) h when it was 20 h (x+/-SD). Parturition and viability, birth weight and weaning weight of piglets were normal. The proportion of sows in trial 2 that showed increased body temperature during the first 3 days post partum was reduced from 22.9% in the control group to 8.6, 14.3 and 7.1% in the three groups receiving just PG or PG and oxytocin after 24 or 20 h, respectively.
Four consecutive trials were conducted to investigate the possibility of controlling the time of ovulation in prepuberal gilts pretreated with PMS and HCG. In trial 1 it was shown that the GnRH analog Hoe 766 was superior to other compounds tested. The following trial revealed that 10 mug of that analog is the optimal dose to elicit an ovulatory response. In trial 3 it was found that the majority (73%) of gilts had started ovulating by 39 h after Hoe 766 injection. Individual gilts started ovulating up to 4 h sooner or up to more than 5 h later. Apparently the ovulatory process of an individual gilt extends over a period of 4 - 5 h. Double insemination of 9 gilts at 34 and 41 h after Hoe 766 resulted in fertilization rates and litter sizes that compared favourably with those of corresponding gilts treated with HCG.
Intravenous injection of 10.0 micrograms/kg body weight synthetic corticotropin (1-24 ACTH) into chronically cannulated boars resulted in significantly elevated plasma corticosteroid and testosterone levels between 20 and 140 min (corticosteroids) and 20--80 min (testosterone) after injection. Administration of lysine-vasopressin (LVP) at doses of 0.1, 0.2 and 0.4 IU/kg body weight elicited a significant increase of plasma corticosteroids between 20 and 40 min after injection; on the other hand, plasma testosterone concentrations tended to fall when compared to pre-treatment levels. From our results it can be concluded that exogenously applied ACTH can effectively stimulate the release of corticosteroids and testosterone. Intravenous administration of LVP results in significantly, although not maximally increased plasma corticosteroid concentrations; the release of endogenous ACTH induced by LVP injection, on the other hand, appeared to be too small to stimulate testosterone release significantly.
Four trials were conducted to investigate the suitability of a gestagen implant (Norgestomet, Intervet) for estrus synchronization and superovulation in suckler cows and heifers kept under field conditions in Germany. In trial 1 out of 17 heifers treated 12 responded with one ovulation each. In trial 2 57 suckler cows were treated at the University experimental farm. Of 23 cows treated sooner and 34 cows treated later than 50 days post partum one (4 %) and 16 (47 %) respectively calved at the expected time. Trial 3 was a field trial involving 126 suckler cows and 21 heifers. Of 24 cows treated sooner and 102 cows treated later than 50 days post partum 17 % and 52 % respectively calved at the expected time. Of the 21 heifers only 19 % calved at the expected time. In trial 4 superovulation of 13 cows and 17 heifers resulted in 62 % and 94 % responding with 10.0 +/- 2.5 and 11.1 +/- 3.0 (x +/- SD ) ovulations per animal respectively.
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