4 September 2009

6 minute read

Therefore, to meet the food requirement of the growing population we need to optimize our livestock production. There is no denying the fact that optimum production from dairy animals is dependant upon efficient reproduction. The sexual rest period after parturition has been reported to prolong by 9.7 ± 0.8 months in cows, particularly in rural areas (Kumar and Purbey, 1987) thus increasing the calving interval. There is substantial evidence indicating that a calving interval of 12 months or less for dairy cows results in more milk production per day in the herd and maximum production of replacement stock (Britt, 1970). Cows in herd with short calving interval (360-374 days) averaged about 132 kg more milk per lactation than cows in herds with longer calving interval of more than 450 days (Bozworth et al., 1972). The recent trend developed in light of above works that cows must conceive by 85 days postpartum to deliver the next calf within a year.

 “One calf a year” is the fundamental need/objective of dairy farms, but prolonged postpartum anoestrus, particularly in high milk producing animals is a common problem. PGF2α or it’s synthetic analogues enhance the uterine involution in post partum cows leading to early restoration of the ovarian cyclicity (Bretzlaff, 1987) and subsequently early postpartum estrus. Thus, early breeding can be used to shorten the calving interval, thereby increasing reproductive efficiency and productivity. Therefore, the present study was undertaken with the following objectives to study the effect of VETMATE a synthetic analogue of Cloprostenol Sodium.

Materials and Methods

The present study was conducted on 52 freshly calved dairy cows maintained under identical and optimal conditions of feeding and management at Military Dairy Farm, Namkom. The animals were divided into three experimental groups and received the treatment as per following schedule:

• Group I (N=17) : Cloprostenol sodium 500 µg I/M on D4 postpartum
• Group II (N=17) : Cloprostenol sodium 500 µg I/M on D4 postpartum and same dose was repeated on D15
• Group III (N=18) : No treatment was given and acted as control

Twice weekly per rectal palpations were done starting from day 7 post partum to record the time taken for complete involution of uterus. Besides, interval of 1st postpartum estrus, fertile estrus and conception rate were also recorded. The data were tabulated and subjected to Analysis of Variance as per standard statistical methods (Snedecor and Cochran, 1967).

Results

In the animals of treatment group-II, the duration required for uterine involution was shorter (29.176± 1.015 days) as compared to the value obtained for the animals of group -I (36.47 ±1.624 days). However, the animals of group –III (Control) required longest duration (43.11± 1.443 days) for uterine involution. There was significant difference (P< 0.01) between the two treatment groups and control in time taken for complete uterine involution. Similar result was also obtained by Young et al. (1984) with the conclusion that cows with long duration of prostaglandin metabolites had relatively shorter involution time. The present findings regarding uterine involution also corroborates with the observations of Albuaquerque (1986). However, it is not in accordance with Guilbault et al. (1988) who reported that the early postpartum administration of PGF2 α by continuous infusion did not change uterine involution in terms of reduction in size and tissue loss by day 15 and 35 postpartum.

Nezhdanov (1983) observed interval of 23 days for uterine involution in normally calved animal, which is quite less in comparison to the control group (43.11 ± 1.443 days) in the present study. Gier and Marion (1968) reported that histologically involution i.e. reestablishment of endometrial layers takes shorter time of 25 days but uterus acquires normal shape and size in between 40-50 days. As our observations were based on per rectal palpation this may be the reason for comparatively higher time taken for involution in our study as compared to the findings of Gier and Marion (1968) based on histological study.

The first postpartum estrus in treatment Group I (64.16±6.679) and Group II (60.06±9.105) and control (76.60±7.380) did not differ significantly (p>0.05) although the trend reveals that twice treated group (Group II) had lower average time (days) taken for postpartum first estrus followed by group-I and Control. Our findings are in agreement with the findings of Al -Raheem and Al-Ritha (1988) who observed that 83% of PGF2α  treated animal came in estrus within 45 days of calving whereas, McClary et al. (1989), reported that mean days to first service as 71.8 ± 27 days)  and 68.5 ± 28.6 days animals.

The onset of postpartum ovarian activity is not dependant upon uterine involution and hence it appeared that majority of effect induced by PGF2α was utilized for myometrial toning and involutionary process (Inostroza and Sepulveda, 1999). Reports indicates that 85% of bovine uteri contained bacterial flora soon after parturition (Johanns et al., 1967). Therefore, administration of Cloprostenol helped in flushing out of bacterial contamination through lochial discharge from the uterus which has certainly some influences early restoration of ovarian activity.

In the present study, treatment with PGF2α at different stages of postpartum life could not bring uniformity in response with respect to first postpartum estrus interval which is in agreement with the observations of Macmillan et al. (1980), who also reported variable kind of response. Sheshappa et al., (2002) also reported that Prostaglandins along with GnRH improves postpartum reproductive efficiency.

The time taken for first postpartum fertile estrus in Group II (73.77±7.179 days) was shortest followed by Group I (78.50±7.510 days) and Control (99.86±9.148 days), but the difference was not significant. Our findings are in fair confirmation with  (Sinha et al., 1998) who observed the postpartum fertile estrus interval in prostaglandin treated cows was shorter (86.43 ± 4.01 days) than that of untreated control (144.50 ± 5.23 days) whereas Selinger and Stros (1980), reported that the average interval from treatment to conception varied between 41-65 days.

In the present study, overall conception rate was highest (69.23%) in animals treated twice with Cloprostenol Sodium (group II) followed by animals treated only once Group I (66.66%) and control (64.70%).The first service conception rate (66.66%) was also higher in group II followed by group I (60.00%) and control (36.36%). The number of services required per conception was lowest (1.33) in group II, followed by group I (1.70) and control group (1.72).

McClary et al. (1989) observed lower pregnancy rate (41.3%) with first service in prostaglandin (25 mg) treated group on day 14 to day 16. However, average number of services per conception reported was 1.64 which was approximately similar to the finding observed in group I in the present study.

Cloprostenol Sodium administered in early stage of postpartum life may prepare the uterus well due to it’s myometrial activity and therefore, animal could be able to resume their normal physiological secretions. This overall preparation of the uterus, favored better conception. Therefore, the conception rate and first service conception rate were apparently higher in treatment groups than the control.

Selinger and Stros (1980) reported more number of inseminations required per conception in treated group (1.75) and control (2.25) compared to present findings. Macmillan and Day (1982) reported high pregnancy rate to first A.I. (69%) in prostaglandin treated cows as compared to untreated cows (60%).

Sinha et al. (1998) reported significantly higher conception rate (P<0.01) in treated group (Dinoprost administered just after parturition) in comparison to control, which differed from the present findings which might be due to variation in salt used (Dinoprost vs Cloprostenol). Fernandes et al. (2002) also observed that administration of Cloprostenol postpartum, improved the reproductive performance of dairy cows and recorded quite low (1.96 ± 0.52) number of A.I. required per conception in twice treated group in comparison to control.

September 2009