Ovum pick-up in dairy heifers: does it affect animal well-being?

The aim of the present study was to assess the effects of the ovum pick-up (OPU) technique on animal well-being. Eight dairy heifers were subjected to 4 months of twice-weekly OPU. The physiological response to OPU was recorded in four heifers at two sessions, at the beginning (time 1) and at the end (time 2) of the 4-month period. Heart rates were measured and blood was analysed for cortisol, vasopressin and PG-metabolite before, during (every 5 and 2(1/2) min), and after the OPU sessions. Reactions to each subprocedure of OPU ('restraint', 'epidural', 'device in' and 'puncture') were closely observed. In all heifers, reactions to the OPU procedures were also noted throughout the experimental period, and changes in routine behaviour, oestrous behaviour, body temperature, or other clinical traits were recorded. Subsequent to the experiment, the ovaries and tails were carefully inspected. At time 1, there was an insignificant increase in heart rate and cortisol throughout the OPU procedure. At time 2, these two parameters increased significantly, but both parameters declined to pre-OPU levels 10 min after completion of the procedure. No significant changes were seen in vasopressin or PG-metabolite at time 1 and time 2. Behaviourally, the heifers showed the strongest response to epidural anaesthesia, with a tendency for more intense response during the late 4-month sessions. The response to 'device in' and 'puncture' varied among individuals independently of time. There were no changes in the routine or oestrous behaviour throughout the experiment and no signs of clinical disorders. No major pathological changes were macroscopically seen in the ovaries and tails subsequent to the 4 months of OPU. In conclusion, the heifers showed a response to OPU, mostly to administration of epidural anaesthesia. However, we demonstrated that epidural anaesthesia can be administered in a way causing less discomfort.

Cryodamage on sperm chromatin according to different freezing methods, assessed by AO test.

OBJECTIVE: To evaluate cryodamage effects on human sperm chromatin, motility and cryosurvival rate after freeze-thawing, compared between liquid nitrogen vapour and computerized program freezer, assessed by acridine orange staining method (AO test). MATERIAL AND METHOD: Fifty semen samples were used. After semen analysis, each semen sample was mixed with cryoprotective media and divided into 2 straws. The first straw was frozen with liquid nitrogen vapour and the second with computerized program freezer. After 1 month of cryostorage, semen samples were thawed. Sperm chromatin integrity, motility, morphology, vitality and sperm cryosurvival rate were determined. RESULTS: DNA damage was significantly greater (p < 0.001) following freezing with liquid nitrogen vapour than with computerized program freezer. Furthermore, the computerized program freezing method significantly provided superior post-thaw sperm motility, vitality and cryosurvival rate, compared with the liquid nitrogen vapour freezing method. CONCLUSION: Computerized program freezing is recommended as a first choice method for routine cryostorage.

Two different schemes of twice-weekly ovum pick-up in dairy heifers: effect on oocyte recovery and ovarian function.

The aim of the present study was to compare two different schemes of twice-weekly ovum pick-up (OPU), continuous (C) and discontinuous (DC), with special emphasis on differences in oocyte yield and quality, estrous cyclicity, ovarian dynamics, and progesterone production. Subsequent to characterization of their normal estrous cycles (pre-OPU period), eight dairy heifers were subjected to 4 months of twice-weekly OPU under two different schemes: the DC (OPU restricted to Days 0-12 of the cycle) and the C schemes. Effects of the two different schemes on oocyte yield, quality, and in vitro competence, together with effects on ovarian dynamics and progesterone production, were monitored. The mean numbers of punctured follicles and recovered oocytes per session were slightly higher (not significant (n.s.)) using the DC scheme, but in total, similar numbers of oocytes were obtained. The quality of the oocytes as well as cleavage rate after in vitro fertilization of the oocytes did not differ between the two OPU schemes. There was no influence of a corpus luteum (CL) producing progesterone on the oocyte yield and quality, whereas the presence of dominant follicles appeared to decrease the number of recovered ooctyes. During the pre-OPU period, all heifers showed normal cyclicity. In the DC scheme, the heifers showed regular and normal cyclic activity throughout the puncture period, with one to two complete follicular waves during the interval from the last OPU to the next estrus. In the C scheme, the heifers occasionally revealed cyclicities with irregular interestrous intervals and weaker signs of estrus. No complete follicular waves were seen during the OPU period in this scheme. The CL developed from the ovulation of the preovulatory follicles in the DC scheme showed similar characteristics to the CLs of the pre-OPU period; however, the CL-like structures from the puncture of follicles, in both the DC and the C schemes, revealed a shorter life span and inferior competence in producing progesterone (P<0.05). The present results indicate that the DC OPU scheme, which allows animals to go into natural ovulation prior to the first OPU, does not affect their ovarian function, whereas the C OPU scheme does. Our study further demonstrates that an equal number of oocytes can be obtained with both schemes, but that fewer OPUs are needed when the DC scheme is applied.

Effects of repeated follicular punctures on ovarian morphology and endocrine parameters in dairy heifers.

Three experimental and three control heifers were included in the study. After a control period (CP), the experimental heifers were subjected to 4 and 5 weeks of twice-weekly follicular punctures (FPP1 and FPP2) with two oestrous cycles in between. The follicular punctures were performed using the ovum pick-up (OPU) technique. During the CP and FPPs, ovarian activity was monitored by transrectal ultrasonography and analyses of plasma progesterone, prostaglandin F2alpha (PGF2alpha) metabolite, luteinizing hormone (LH), oestradiol and follicle stimulating hormone (FSH) levels. The animals were slaughtered 7 days after cessation of FPP2 and their ovaries examined. The control animals were monitored for their oestrous cyclicity and were then ovariectomized and the ovaries examined. Despite the absence of ovulation, the formation of corpus luteum (CL)-like structures could be ultrasonographically observed during FPPs. These structures either had characteristics comparable to those of the CLs during the CP (group 1) or were smaller and had a shorter life span and (or) luteal active phase with a lower progesterone production (group 2). In group 1, CL-like structures emanated from punctures of large-sized follicles on or close to the days on which the animals showed oestrus and had a rise in oestradiol and LH. In group 2, the structures developed from punctures of smaller-sized follicles and no oestrus nor a detectable 1.14 rise was revealed around punctures. During most FPPs, the basal level of LH was at zero. During all FPPs, a significant rise in FSH level occurred on the day following the day of puncture. To conclude, repeated follicular puncture appeared to alter slightly endocrine profiles and cause minor morphological changes in the ovaries. Both the macro- and microscopic examinations revealed the presence of luteal structures and follicles of various sizes in the ovaries of all heifers studied. The connective tissue in the ovarian tunica albuginea of the experimental heifers was significantly thicker than that in controls (P < 0.001).

The effect of repeated follicular puncture on ovarian function in dairy heifers.

Three dairy heifers were examined during three consecutive oestrous cycles (control period, CP). Subsequently, the animals were subjected to 4 and then 5 weeks of twice-weekly ovum pick-up (OPU) (FPP1 and FPP2, respectively) with a recovery period (RP) of two consecutive oestrous cycles between FPP1 and FPP2. After FPP2, the animals were slaughtered and the ovaries were macroscopically examined. Throughout, ovarian activity was monitored by transrectal ultrasonography and concentrations of plasma progesterone. During CP, all the heifers showed normal cyclicity. During FPPs, the heifers occasionally presented oestrous activity. Corpus luteum (CL)-like structures developed from punctured follicles with diameters and life-spans varying from smaller and shorter than those in the CP (P > 0.05) to equal to those in the CP. There was a tendency for a lower number of emerging and punctured follicles in the presence of a CL-like structure. Subsequently to FPP1, all heifers regained normal cyclicity. A thickening of the ovarian tunica albuginea and a slight hardening of the ovaries were found postmortem. In conclusion, dairy heifers can occasionally show cyclic activity and form CL-like structures during twice-weekly OPU. Further, OPU did not seem to cause any major negative effects on ovarian structure and subsequent ovarian function.