ULTRASONOGRAPHIC ASSESSMENT OF EMBRYONIC AND FOETAL DEVELOPMENT IN MALABARI GOATS
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Date
2017-02-02
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Kerala Veterinary and animal science university, Pookode
Abstract
The present study was conducted with the objectives to evaluate the accuracy of foetal body measurements for the prediction of gestational age and to design a reference charts for embryonic and foetal body development employing ultrasonography in Malabari goats. The study was conducted at the Goat farm, Instructional Livestock Farm Complex (ILFC) attached to CVAS, Pookode. A total of twenty pluriparous goats aged one to five years with normal oestrous cycles and without any reproductive complications were selected. All the goats were subjected to oestrus synchronisation by double injection protocol of PGF2α (Lutalyse®, 10 mg, Dinoprost tromethamine) at 12 days apart. The goats were monitored for oestrus at every 12 h intervals after second injection of PGF2α by exposing to the apronised bucks. Oestrus signs were graded to assess the oestrus response and goats in standing oestrus were naturally bred with fertile bucks at 48 and 72h. The day of mating was considered as day 0 of gestation. The reproductive performances of goats were assessed by the time of onset of oestrus, duration of oestrus, service rate, the oestrus response and conception rate. All the experimental animals were subjected for transrectal ultrasound scanning by standard procedures for the study of conceptus from Day 15 post-service every day until the confirmation of early pregnancy. Twelve pregnant goats were subjected to ultrasonographic foetometry by measuring different parameters such as foetal crown rump length (CRL), biparietal diameter (BPD), trunk diameter (TD) and femur length (FL). The scanning was carried out at every three days until day 39 by transrectal probe (7.5 MHz) then at every five days interval up to Day 64 by both transrectal and transabdominal probe, thereafter until Day 114 by transabdominal probe (5.0 MHz) alone.
Out of 20 goats synchronised, all the animals expressed the oestrus signs with 100 per cent oestrus response. The time of onset of oestrus was ranged from 24 to 72h after second injection of PGF2α with an average of 49.2 ± 4.07 h and the duration of oestrus was ranged from 30 to 48h with an average of 36.8±3.2 h. In these 20 goats 18 goats completed the service with a service rate of 90 per cent. Among these 18 goats 12 were conceived with a conception rate of 66.67 per cent.
The earliest period at which the embryonic vesicle detected was between 18 to 21 days (n=12) with an average early detection was at 20 ± 0.426 days. The hyperechoic embryo within anechoic embryonic vesicle was detected between Day 21 to Day 24, with an average period for early detection of embryo was at 23.833 ± 0.112 days. Similarly, the first detection of embryonic heartbeat was between Days 24 to Day 27 with an average period of 25.5 ± 0.45 days.
The gestational sac diameters on Days 18 and 21 post-service were 7.40 ± 0.59 mm and 10.70 ± 0.77 mm, respectively. The foetal CRL was measured by both transrectal and transabdominal ultrasonography from Day 24 to Day 89 at 3-5 days interval. The foetal CRL was ranged from 0.88 ± 0.016 cm to 15.18 ± 0.064 on Day 24 and Day 89 respectively. Ultrasonographic measurement of foetal BPD was carried out between Day 30 to Day 114 which was ranged between 0.81 ± 0.004 cm to 4.70 ± 0.019 cm. Beyond Day 114, measurement of foetal BPD was difficult due to compression of the foetal head by growing foetal parts. On the other hand, foetal TD was measured from Day 44 to Day 114 which was ranged from 1.48 ± 0.007 to 5.99 ± 0.014 cm. The foetal FL was measured from Day 59 to Day 114 which ranged from 0.93±0.006 cm to 4.13 ± 0.009 cm. It was easy to measure the foetal FL in fourth month because femur was almost ossified.
All the measured data were subjected to statistical analysis by linear regression model. The relationship between the foetal CRL, BPD, TD and FL were significant with the gestational age at one per cent level (P ≤ 0.0001) and fitted to the regression line.
The relationship between the CRL (x) in cm and the gestational age (y) in days was plotted into a linear regression equation, y = 24.226+4.529x with the coefficient of determination (R2) of 0.967.
A highly significant (P≤ 0.0001) relationship was existed between BPD (x) in cm and gestational age (y) in days of Malabari goat foetuses and the coefficient of determination was R2 = 0.968. The data were plotted in a linear regression curve to derive a linear regression equation, y = 20.822 +20.91x.
The foetal TD increased linearly from Day 44 to Day 114 with the coefficient of determination of R2= 0.997. The relationship between the crown rump length (x)
in cm and the gestational stage (y) in days was plotted into a linear regression equation, y = 24.63+14.93x.
A highly significant (P≤ 0.0001) relationship was existed between FL (x) in cm and gestational stage (y) in days of Malabari goat foetuses and the coefficient of determination was R2 = 0.978 and plotted in a regression equation, y=49.33+16.23x.
From the present study it is evident that the synchronisation by double PGF2α injection regimen is more efficient and cost effective method with higher conception rate (66.67 per cent). The pregnancy can be identified as early as day 18 transrectal ultrasonography which is more reliable than any other method. The gestational equations designed in our study can be used to estimate the age of the foetus with high accuracy within a limited period especially in Malabari goats. Since in most of the cases the mating date is unknown, this gestational age estimation by ultrasonography by the gestational equations helps in drying off lactating does, induction of kidding and to take care of the pregnant doe by planned nutrition and management.
Description
The present study was conducted with the objectives to evaluate the accuracy of foetal body measurements for the prediction of gestational age and to design a reference charts for embryonic and foetal body development employing ultrasonography in Malabari goats.
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