CONCEPTION RATES IN ESTRUS SYNCHRONIZED DECCANI EWES INSEMINATED WITH FRESH AND PRESERVED SEMEN
2015-10-01
M.SC
A fertility study was undertaken on fixed time cervical artificial insemination in Deccani ewes at 48 and 56 h of sponge removal after estrus synchronization with progesterone impregnated intravainal sponges containing 350 mg of progesterone in situ for 12 days followed by eCG injection at the time of the sponge removal. For this study a total of 70 non pregnant, healthy maiden (above 1 year age) and 2 months post partum Deccani ewes with good body condition score (3) were selected after screening with ultrasound scanner twice at an interval of 20 days and were maintained in semiintensive feeding system. Four matured fertile Deccani rams aged 2-5 years with good breeding soundness and producing good quality semen were selected and maintained separately. Ram semen was collected and evaluated for motility, viable count and concentration and it was diluted with EYC, TFCEY and CME diluents to get final concentration of 400 million spermatozoa in 0.2 ml of semen. Fresh diluted semen was having ≥ 70 per cent progressive motility and ≥70 per cent viable count and chilled (50C) and 24 h stored semen having ≥ 500 per cent progressive motility and ≥60 per cent viable count was used for fixed time cervical artificial insemination. All the ewes selected were synchronized for estrus. At the end of synchronization ewes were randomly allocated to group 1, 2 and 3 consisting of 10, 30 and 30 ewes in the respective groups. In group 1 termed as “control”, ewes were bred with natural service. Group 2 and 3 were further subdivided to A, B and C each consisting of 10 ewes. Ewes in groups 2A, 2B and 2C were inseminated with semen diluted with EYC, TFCEY and CME as fresh, respectively. Ewes in groups 3A, 3B and 3C were inseminated with semen diluted with EYC, TFCEY and CME, chilled at 50C and stored for 24 h. Although CME recommended for room temperature storage after semen dilution, motility and other parameters were not maintained up to 24 h at room temperature storage. Hence, the same diluted semen was stored at refrigeration temperature (50C) and used for insemination. Ewes were observed for estrus from 12 h to 108 h after intravaginal sponge withdrawal. Pregnancy diagnosis was conducted on 30, 45 and 50th days after artificial insemination by using ultrasonography and group wise conception rates were recorded. The efficacy of synchronized estrus was measured in terms of estrus response rate, interval between sponge removal and onset of estrus, duration of estrus and estrus intensity. The mean estrus response rate recorded was 78.57 per cent. The average time taken for onset of estrus was 36.61±1.86 h and ranged from 24 to 50 h after sponge removal. Estrus response was observed in 78.18 per cent of ewes between 24 h to 48 h after sponge withdrawal. The mean duration of estrus recorded was 30.48±1.8 h ranged from 20-48 h. A significant negative correlation of the estrus onset interval and duration of estrus was found. Estrus intensity was graded on 1 to 5 scale (high to low) and 30.00, 25.71, 11.43, 11.43 and 21.43 per cent ewes exhibited the respective estrus grades. The conception rates in respective estrus intensity grades were 76.19, 50.00, 62.50, 37.50 and 13.33 per cent and concluded that there was significant positive correlation between estrus intensity and conception rate. Conception rate obtained using freshly diluted semen in group 2A, 2B and 2C were 60.0, 50.0 and 50.0 per cent, respectively. Whereas, 50.0, 30.0 and 40.0 per cent conception rates were recorded in group 3A, 3B and 3C, respectively with the usage of chilled and stored semen. The overall conception rates achieved diluent wise were 55.0, 40.0 and 45.0 per cent, respectively for EYC, TFCEY and CME groups. As there was no significant difference in between the groups it was concluded that the three diluents were equally effective in preserving the Deccani ram semen for 24 h at refrigeration temperature without impairing the fertility. In between the diluents also there was no significant difference in terms of conception rate. In control group conception rate recorded was 70.0 per cent and did not find any significant difference when compared with experimental diluents in other two test groups i.e. group 2 (bred with fresh semen) and group 3 (bred with chilled and stored semen) and concluded that synchronization and fixed time artificial insemination can be used in ewes without much decrease in fertility when compared with the natural service. Age wise conception rate was 66.67, 47.06, 40.00 and 37.50 per cent, respectively in ≤2, 2-4, 4-6 and >6 years age groups. Difference between overall 25 days non return rate and conception rate using ultrasonography was 37.14 per cent and concluded that non return rate as method of an early pregnancy diagnosis is questionable. Accuracy of pregnancy diagnosis using transrectal ultrasonography at 30 days gestational age was 91.42 per cent and on 45th day it was increased to cent per cent. Some of the fetal parameters for Deccani sheep breed were mean Placentome Diameter (PLD) at 30th day of gestation was 0.96 cm; at 45th day of gestation mean PLD, Amniotic Sac Diameter (ASD) and Crown Rump Length (CRL) were 1.86, 4.32 and 1.95 cm, respectively and at 50th day of gestation mean PLD, Fetal Abdominal Diameter (FAD) and Bi Parietal Diameter (BPD) were 2.00, 2.08 and 1.62 cm, respectively. The study concluded that even though there was no much difference in between three experimental semen diluents; EYC diluent is recommended for liquid ram semen storage at 50C even up to 24 h for fixed time artificial insemination in Deccani ewes as it is easy to prepare and economical. FTAI fertility rates in Deccani ewes were similar to natural service. Hence, estrus synchronization with progesterone sponges and FTAI can be recommended for breeding in Deccani sheep flocks managed in villages of this region as a tool of assisted reproductive technology to increase the productivity of this breed and at the same time to conserve this valuable germplasm.
PVNR TVU
Veterinary Gynaecology and Obstetrics
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2015 D-424 G.Srinivas VGO PG.pdf