Effect of postpartum medical manipulation on reducing uterine bacterial contamination and improving reproductive performance in dairy cows

• Main Authors: Shih-Pin Chen, 陳世彬
• Other Authors: 陳鵬文
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/35115038074949785387

碩士 === 國立中興大學 === 獸醫學系暨研究所 === 94 === Postpartum (pp) bacterial contamination in the uterus contributes to endometritis which may suppress ovarian follicle function in dairy cows. Retained placenta (RP) is mainly associated with greater bacterial contamination in the uterus and usually induces endometritis which causes infertility. Administration with exogenous hormone after puerperium can monitor estrus and the timing of ovulation with minor needs for estrus detection. The aim of this study was to use medical manipulation to diminish postpartum bacterial contamination in the uterus and improve subsequent reproductive performance in dairy cows. Sixty Holstein dairy cows were used for this study. Twenty-six normal postpartum cows were grouped as clinically healthy animals (G1), and 34 cows having RP were divided into treatment groups. Of these, 16 cows were treated with ceftiofur (G2), while the remaining 18 cows received traditional treatment (G3). Intrauterine samplings with a following infusion were performed in G1 and 8 of G2 on Day 20 and 30 pp, respectively. All animals in G1 and G2 were assigned to undergo exogenous hormonal manipulation at fixed time. The results indicated that the mean gestation period of cows with RP was significantly shorter than that in G1 (265.9 ± 4.4 vs. 279.0 ± 1.0 days, P < 0.01). Moreover, 43.3% of cows with RP had the gestation period below 271 days. The results of bacteriology indicated that twelve strains of bacteria, including 7 in G1 and 5 in G2, were isolated from 8 cows, half of them belonged to G1 and G2. Between two samplings, the proporation of positive bacteriology in G2 decreased from 50.0% to 12.5%. Additionally, cows with positive endometrial cytology coincided with the results of bacteriology. The proportion of positive endometrial cytology in G2 decreased from 50.0% to 25.0% between two samplings. There were 11.7% of cows with purulent vaginal discharge on Day 20 pp, but 91.2% of them were found having either no mucus or translucent mucus on Day 30 pp. Ultrasonography revealed that the days from calving to the first ovulation in G3 was significantly longer than that in G1 and G2 (28.8 ± 3.1 vs. 19.2 ± 0.9, 19 ± 1.6 days，P < 0.05). Comparison of reproductive performance indicated that the mean of days open in G3 was significantly longer than that in G1 and G2 (270.3 ± 60.4 vs. 86.3 ± 8.2 and 130.5 ± 21.1 days, P < 0.05), and the pregnancy rate within 150 days pp in G3 was lower than that in G1 and G2 (16.7% vs. 73.9% and 43.8%). The mean of days open in G2 was significantly longer than that in G1 (P < 0.05), but there were no significant differences in pregnancy rate and number of insemination between G1 and G2. Furthermore, the proportion of cows culled was higher in G3 than that in G1 and G2 ( 27.8% vs. 11.5% and 18.8% ). As a summary, the mean gestation period of cows with RP was significantly shorter than that in normal postpartum cows. Treatments with oxytocin, ceftiofur and intrauterine infusion were efficacious on reducing the bacterial density in the uterus and advancing the resumption of ovarian activities. In addition, exogenous hormonal manipulation after puerperium could improve subsequent reproductive performance. It was concluded that medical manipulation was efficacious on reducing postpartum bacterial contamination and improving subsequent reproductive performance in dairy cows.