EFFECT OF BREED, PARITY AND BODY CONDITION ON OVARIAN RESPONSE AND CONCEPTION RATE OF BORAN AND ZEBU-HOLSTEIN CROSSBRED DAIRY COWS SUBJECTED TO OVSYNCH OR CO-SYNCH PROTOCOL
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2018-06
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Abstract
A study was carried out to evaluate the effect of parity, breed and body condition on ovarian response and conception rate of Boran (n=17) and Zebu-Holstein cross (n=18) dairy cows bred by Ovsynch or Co-synch timed artificial insemination. Ovarian response (ovulation and luteolysis) and pregnancy diagnosis were made by ultrasound and progesterone assay. For progesterone assay blood samples were collected at day 0, 5, 7, 9, 15 and day 21 of the experiments. The overall ovulation rate was 85.7%, of which 90% and 80% in Ovsynch and Co-synch, respectively. In this study, body condition, breed, and parity did not influence ovulation rate in both protocols (P>0.05). The overall conception rate was 60%, (55% in Ovsynch and 66.7% in Co-synch). Conception rate was relatively higher in Boran (70.6%) compared to crossbred (50%). However, the difference in conception rate was not statistically significant (P>0.05). Conception rate was significantly higher in primiparous (73.7%) compared to multiparous dairy cows (43.8%) (P <0.05). Conception rate was not influenced by body condition and breed in both protocols. The mean diameter of corpus luteum was 18.3±1.31 mm for animals with good body condition while it was 11.84±0.93 for those with low to moderate body condition and mean difference of corpus luteum was statistically significant (P<0.05). However, breed and parity did not influence mean size of corpus luteum. Twenty-seven cows (77.1%) had functional corpus luteum on day seven of the treatment (progesterone >1 ng/ml) and the progesterone was reduced to less than 1 ng/ml in 22 cows (81.5%) on day nine after PGF injection. In five cows (18.5%) the progesterone remained at levels greater than 1 ng/ml after PGF2α treatment (day 9). The result of this study demonstrated that conception was higher in Boran cows than Zebu-Holstein cross. Based on the result, it could also be concluded that both Ovsynch and Co-synch can give acceptable level of conception with the established TAI protocols.
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A Thesis Submitted to College of Veterinary Medicine and Agriculture of Addis Ababa University in Partial Fulfillment of the Requirements for the Degree of Master of Science in Veterinary Obstetrics and Gynecology
Keywords
Boran, conception rate, Co-synch