Veterinary Obestrics and Gynaecology

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Browsing Veterinary Obestrics and Gynaecology by Author "Dr. Tefera Yilma"

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    Association of Subclinical Mastitis and Lameness with Reproductive Performance and Subclinical Endometritis in Zebu X Friesian Crossbred Dairy Cows In And Around Jimma Town Dairy Farms, Ethiopia
    (Addis Ababa University, 2023) Nuraddis Ibrahim; Prof. Fekadu Regassa; Dr. Tefera Yilma; Prof. Tadele Tolosa
    A longitudinal observational study was conducted to assess the association of subclinical mastitis and lameness with reproductive performance and subclinical endometritis in crossbred dairy cows. The California Mastitis Test and cytobrush technique were used to screen for subclinical mastitis and subclinical endometritis, respectively. Samples positive for subclinical mastitis were subjected to bacteriological analysis. Lameness in cows was also assessed using a 5-point locomotion scoring system. Analysis of progesterone and cortisol concentrations in blood serum of cows was performed using electrochemiluminescence immunoassay “ECLIA”. A total of 84 clinically healthy cows were tested for subclinical mastitis using the California Mastitis Test. The prevalence of subclinical mastitis at cow level was 51.2% (43/84). The prevalence of subclinical mastitis in 108 lame cows was 53.7% (58 of 108). Based on the results, the 192 cows according to the study were divided into the following four groups: Group I (n=43) cows with subclinical mastitis, Group II (n=50) are lame cows, Group III (n=58) lame cows with subclinical mastitis and Group IV (n=41) healthy cows (control group). Lame cattle are also classified as no lameness, mild lameness, moderate lameness, lameness, and severe lameness. Mean number of days from calving to first mating interval was highly significantly longest in lame cows with subclinical mastitis (122.71±28.6) than for lame cows (120.98±31.3), subclinical mastitis cows (120.51±24.5) and healthy cows (85.15±28.3) (P<0.05). Mean number of services per conception was significantly highest in lame cows with subclinical mastitis (3.66±1.31) than lame cows (3±1.6), subclinical mastitis cows (2.51±0.83) and healthy cows (1.59±0.81) (P<0.05). Cows clinically lame had a longest calving to first service interval when compared with cows which were never lame and those mildly lame. The difference was significant (P<0.05). Lowest conception and pregnancy rates at first services were observed in lame cows with subclinical mastitis. Cows that were clinically lame had a lowest conception rate at first services than cows that were never lame and mildly lame, although the difference was not statistically significant (P>0.05). Clinically lame cows had a lowest pregnancy rate at first services than cows that were never lame and mildly lame (P<0.05). Risk factors analysis revealed that prevalence of subclinical mastitis, lameness and in lame cows with subclinical mastitis significantly differed with the parity and body condition score (P<0.05). The present study revealed that subclinical mastitis and lameness were significantly and directly associated with subclinical endometritis (P<0.05). Progesterone concentrations highly decreased in lame cows with subclinical mastitis than in subclinical mastitis and lameness alone while the cortisol concentrations also highly increased in lame cows with subclinical mastitis. The major bacterial isolate was Staphylococcus aureus. In conclusion these results provide further evidence that combined occurrence of subclinical mastitis and lameness inflict harmful effects on fertility and hormonal profiles of dairy cows than those diagnosed with mastitis and lameness alone, emphasizing the relevance of mastitis and lameness control programs in dairy farms.
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    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
    (2018-06) Alebachew, Tilahun; Dr. Tilaye Demissie, Dr. Alemayehu Lemma; Dr. Tefera Yilma
    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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    Modulation of ovarian function to improve suitability for reproductive biotechnology application in local and crossbred Cattle
    (Addis Ababa University, 2022) Tilaye Demissie; Prof. Alemayehu Lemma; Dr. Tefera Yilma; Dr. Tamrat Degefa
    Ovarian function is influenced by various intrinsic and extrinsic factors. Breed related variations, nutrition; local environmental conditions are among the major sources of differences in response to application of reproductive biotechnologies. It is of paramount importance to understand specific ovarian functions amenable to modifications in order to improve suitability for advanced technologies such as fixed time artificial insemination (FTAI), ultrasound guided ovum pickup (OPU) and in vitro embryo production (IVP). In the first part of this study, estrus sign/s that best correlate with the time of ovulation and pregnancies rate to insemination at FTAI was evaluated in 27 Boran*Holstein crossbred dairy heifers. The second part explored ovarian response to estrus synchronizing hormones by cow realated factors and pregnancy rate to FTAI after ovulation synchronization using GnRH and PGF2α with or without progesterone augmentation (CIDR vaginal insert) in native Borans and Boran*Holstein crossbred dairy cows. The third part assessed the effect of CL, follicle ablation, administration of different doses/frequency of FSH, and different coasting period in Boran cows. Result indicated that, the frequency of occurrence of various estrus signs, length of estrus, and onset of estrus, was not affected (P>0.05) by estrus type. Irrespective of estrus type, standing estrus (r=1, P<0.05), and mounting other heifers (r=0.87, P<0.05) showed a strong positive correlation with ovulation time. Ovulation rate and pregnancy rate on day 32 was significantly higher (P<0.05) in cows that received CIDR augmentation to the double GnRH and PGF2α protocol compared to those that did not. When time of insemination was considered conception rate to insemination 19h post second GnRH administration was significantly higher (P<0.05) for Ovsynch group compared to Cosynch group. Presence of CL did not influence mean number of follicles aspirated, oocyte recovery rate, and quality of oocyte and cleavage rate. Divided dose of 175 IU FSH and 350 IU FSH ignificantly (P<0.05) improved the mean number of medium and large follicles compared to single dose while the 48h coasting period significantly improved (P<0.05) oocyte grade, oocyte maturation rate and cleavage rate. It could be concluded that standing estrus best predict ovulation time. Insemination scheduled at 19h of standing estrus significantly increase conception rate as this sign best correlates with the mean time of ovulation. Further, CIDR priming to the synchronization protocol greatly improve ovulation rate and subsequent pregnancy. Follicular ablation and administration of divided doses of FSH prior to OPU and a coasting period of just 48hr improves follicular population and oocyte recovery rate. Hwever, future studies are recommended to answer why Boran cows’ with morphologically smaller CL than Boran*Holstein cows have larger amount of progesterone than Boran*Holstein. Why some heifers that ovulated to D0 GnRH did not ovulate to D9 GnRH. As some of the CL that were present at day of start were lost at PGF2α the effect of stages of estrus cycle at the start of hormone treatment shoud be assessed both in Boran and Boran*Holstein cattle.
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    Ovarian follicular dynamics and conception rate in Boran cows previously subjected to repeated ovum pick up
    (Addis Ababa University, 2021) Gezahegn Berhan; Dr. Tefera Yilma; Dr. Tilaye Demissie
    The study was conducted to investigate the effect of repeated ovum pick-up on ovarian follicular dynamics, serum estrogen and progesterone pattern, and the conception rate of Boran cows. Eight Boran cows were estrous synchronized by 500μg PGF2α at 11 days intervals. After the second PGF2α injection ovaries were scanned by transrectal ultrasonography every 12 hrs for the first two days and then every 6 hrs until ovulation. From the day of ovulation onwards, the ovaries were examined twice daily (at 12 hrs interval) to characterize the growth and regression pattern of ovarian follicles during two consecutive estrous cycles. A blood sample was collected every other day to evaluate estrogen and progesterone concentrations. The mean (±SEM) IOI was 21.1±1.19 days for cows with two waves and 22.66±0.57 days for cows with three waves. The length of the IOI was not significant (P>0.05) by follicular waves. The mean (±SEM) number of days from the emergence of cohort follicles to ovulation of dominant follicle of the ovulatory wave was significantly (P<0.05) greater (10.80±1.03 days) for two wave cows than three-wave cows (7.50±0.70 days). The mean (±SEM) diameter of the preovulatory follicle was significantly (P<0.05) larger for cows with two waves (14.29±1.36mm) than for cows with three waves (12.30±1.01mm). The mean (±SEM) growth rate of the dominant follicle that finally ovulated was significantly (P<0.05) higher (1.16±1.2mm/day) in the three-wave cycle than in two-wave cycles (0.85±0.1mm/day). The mean (±SEM) serum concentrations of estrogen and progesterone were 28.73±6.56 pg/ml and 0.88±0.40 ng/ml, respectively during the proestrous and estrous. While during the late diestrous cycle, serum estrogen and progesterone were 11.01±1.61pg/ml and 2.67±0.12 ng/ml, respectively. 87.5 % of cows were found conceived on ultrasound 32 days after insemination. In conclusion, based on ovarian follicular dynamics, serum estrogen and progesterone pattern, and conception rate repeated ovum pick does not significantly affect the fertility of Boran cows. Boran cows were characterized by a higher incidence of two-wave cycles.