Browsing by Author "Kutelo Kussia"

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    Evaluation of Biochemical Determinants of Successful Conception in Dairy Cows in and around Bishoftu, Ethiopia
    (Addis Abeba University, 2024) Kutelo Kussia; Prof. Alemayehu Lemma
    The influence of biochemical characteristics of cervical mucus at the time of estrus were evaluated on conception rates of normal-cycling and repeat-breeding dairy cows. A total of 62 Holstein-Friesian dairy cows, 38 normal-cycling and 24 repeat-breeding cows, were included in the study. Vaginal electrical resistance (VER) was measured before artificial insemination and cows were categorized into three VER groups (150-180, 181-220 and >220 Ω). The cows were also grouped into three body weight ranges (300-350, 351-400 and 401-450 kg). Cervical fluid parameters including pH, spinnbarkeit, sperm penetration and crystallization patterns were measured or scored and pregnancy was diagnosed by ultrasonography after 30 days post-AI The overall conception rate was 54.84% with a significant difference (P<0.05) between normal cycling cows (63.2%) and repeated breeders (41.7%). The mean (±SD) VER was in the order of 219.03±66.17Ω and 221.67±41.77Ω for normal-cycling and repeated breeding cows, respectively. The average pH and spinnbarkeit value of cervical fluid were 7.38±0.32, 5.76±2.2cm in normal cycling and 7.32±0.27, 5.85±3.77cm in repeat breeder cows, respectively. The mean(±SD) VER of pregnant and nonpregnant cows were 202.15±31.15Ω and 241.79±73.56Ω, respectively. Body weight, timing of insemination and VER showed significant effects (P<0.05). Conception rates were highest for cows weighing 351- 400 kg(75%), inseminated 7-12 hours (71.43%) after standing estrus and VER of 181-220 Ω 84.21%). Interestingly, although there was some tendency for influence of the cervical fluid pH, this was not statistically significant, but sperm penetration, spinnbarkeit value and crystallization patterns of cervical fluid did (P<0.05). Cows with normal sperm penetration (72.2%), spinnbarkeit of 7-9 cm (87.5%) and typical crystallization patterns of cervical mucus (76.47%) had comparatively higher conception rates. In conclusion, sperm penetration, spinnbarkeit, vaginal electrical resistance and crystallization pattern are useful predictors of optimal insemination timing in Holstein cows.