首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
An association with a rank correlation of 0.55 (p = 0.06) was obtained between monthly rainfall and monthly abortions for a group of 24 farms in tropical Australia where cows grazed predominantly summer rain-dependent pasture. A similar association was found among cows grazing nitrogen-fertilised, irrigated pasture in winter in the same area. On farms with irrigated pasture the first service conception and abortion rates in herds which grazed intensively during the night (abortion 8.9%; first service conception 42.9%) differed significantly from those which grazed during the day (abortion 6.4%; first service conception 52.9%), and this suggested that increased abortion rates and decreased first conception rates may be part of the one syndrome. An hypothesis was developed that the feeding of immature nitrogen-fertilised pasture, rich in protein and stimulated by rain or irrigation, is associated with an increased abortion rate and a depressed conception rate. Other evidence included an increased susceptibility of first lactation cows to abortion, a lower abortion rate in late pregnant dry cows fed more mature pasture, a 20% repeat abortion rate in the population sampled and the lack of conclusive evidence for infectious and selected non-infectious agents. There were no other observed clinical signs in most aborting cows.  相似文献   

2.
The possible relationship between Coxiella-seropositivity and the reproductive performance of cows during the previous year to the serological screening was examined in three high producing dairy herds. The herds had a history of subfertility (<25% of pregnancies for the total number of AI), abortion (>18% abortions) and a positive polymerase chain reaction test for Coxiella burnetii in the bulk tank milk with an excretion higher than 10(4)Coxiella /ml for all three herds. Antibodies against C. burnetii were detected in 50.2% of the 781 parous cows analyzed. Coxiella seropositivity was linked to placenta retention, to changes in the interval from parturition to conception (with the lowest interval parturition-conception for cows with low level of seropositivity), early pregnancy (cows becoming pregnant before Day 90 postpartum) and maintenance of gestation during the early fetal period, while it failed to affect rates of abortion after Day 90 of gestation or stillbirth.  相似文献   

3.
Epidemiology of bovine abortions in Israeli dairy herds   总被引：1，自引：0，他引：1  
  相似文献   

4.
Twin pregnancies are classified into bilateral (one fetus in each uterine horn: 44%) and unilateral (both fetuses in the same uterine horn, right or left: 56%). The incidence of abortion during mid- to late gestation is approximately 1% in cows carrying bilateral twins and more than 40% in cows carrying unilateral twins. In this period, abortion seems most commonly associated with infectious agents. However, although this imbalanced abortion rate may imply that unilateral twin pregnancy is a non-infectious abortion factor, few available data can describe the cause of abortions in twin pregnancies. The current findings suggest that unilateral twin pregnancy is a non-infectious factor required for the etiological diagnosis of abortion in dairy herds.  相似文献   

5.
The reproductive performance of beef cattle in 5 herds mated all year round in north-west Queensland was examined from 1970 to 1973. Conception rates, conception patterns and branding rates were used to assess annual reproductive performance. The level of loss between the times of confirmed pregnancy and branding was defined. The mean annual conception rate was 83.1% with individual property means ranging from 75.4 to 90.9%. Conception rates for heifers, first calf cows and mature cows were 83.9%, 80.6% and 84.7% respectively. Conception patterns were influenced by seasonal conditions, 68.1% of conceptions occurring in the wet season, between December and May. In this region, conception patterns were highly correlated with rainfall during the previous month. Losses between the times of confirmed pregnancy and branding ranged from 5.9 to 27.7%. Body condition of animals varied and was dependent upon lactation, seasonal and parity effects.  相似文献   

6.
The possible direct relationship between climate variations and abortion in Neospora caninum-infected cows has not been studied. The objective of this study was to determine whether climate changes could be a risk factor for abortion in N. caninum-infected cows, and was based on yearly serological screening for neosporosis and on the confirmation of N. caninum infection on aborted fetuses in two high-producing dairy herds with a mean 27% seroprevalence of N. caninum antibodies. The final population study was comprised of 357 pregnancies in seropositive animals. Logistic regression analysis indicated no significant effects of herd, N. caninum antibody titre, climate variables during the first and third trimesters of gestation, mean and maximum temperature-humidity index values during the second trimester of gestation, and previous abortion on the abortion rate. Based on the odds ratio, a 1-unit increase in lactation number yielded a 0.85-fold decrease in the abortion rate. The likelihood of abortion was 1.9 times (1/0.54) lower for pregnant cows inseminated with beef bull semen compared with Holstein-Friesian bull semen. The likelihood of abortion decreased significant and progressively by factors of 0.5, 0.41 and 0.3 for the respective classes 40-49, 30-39 and <30 rainfall mm during the second trimester of gestation (using the class >or=60 rainfall mm as reference). As a general conclusion, it seems that increased rainfall in a dry environment can compromise the success of gestation in N. caninum-infected cows. Attempts should therefore be made to reduce environment effects during the second trimester of gestation, a period in which the immune response of cows is diminished.  相似文献   

7.
AIM: To identify some production and reproductive effects of calving induction in seasonally calving herds. METHODS: Forty seasonally calving herds entered on the DairyMAN management information system and whose milk yield and reproductive data were recorded, including pregnancy diagnosis results, were included in the study. Cows with an induced parturition were compared with normally calving contemporaries that had the same lactation number and calved at the same time. RESULTS: Milk yield was 1.2 +/- 0.2 litres/cow/day less over the entire lactation for cows induced to calve, with the greatest difference being 2.5 +/- 0.4 litres/cow/day measured in early lactation. The effects on milkfat and protein yield were similar, with 0.04 +/- 0.01 kg/cow/day less milkfat (p < 0.0001) and 0.03 +/- 0.01 kg/cow/day less protein (p < 0.0001). A higher milkfat percentage (+ 0.09 +/- 0.04 %) (p < 0.0001) and protein percentage (+ 0.10 +/- 0.02%) (p < 0.0001) for cows that were induced to calve reduced the effect of a lower milk yield on milkfat and protein production. The first service conception rate for cows induced to calve was 54.4 +/- 3.3%, which was significantly less (p = 0.03) than for cows that calved normally (59.5 +/- 3.3%). Cows induced to calve had a pregnancy rate at the end of mating of 91.4 +/- 2.1%, which was also significantly less (p <0.0001) than for cows that calved normally (93.6 +/- 1.7%). The 21-day submission rates were not significantly different between groups. CONCLUSIONS: This study indicates that, under some New Zealand management conditions, the induction of calving is associated with reduced daily milk yield and inferior reproductive performance.  相似文献   

8.
A retrospective cohort study design was used to investigate the effect of lameness on reproductive performance on 13 commercial Dutch dairy farms. The data were collected during a routine herd health and production control program.

The cumulative 100-DIM (days in milkl) production in the previous lactation of lame cows was higher and the culling rate lower than that of the controls. The 100- and 270-DIM production of the cows with a sole ulcer was higher than that of the control cows. There was no difference in 100- and 270-DIM production between cows with a lameness diagnosis other than sole ulcer and the controls.

Lameness prolonged the interval from calving to first service and the interval from first service to conception. The pregnancy rate at first service was not affected by lameness.  相似文献   


9.
This study examines incidences and timing of abortion in Holstein Friesian dairy cows with advanced twin pregnancies in north‐eastern Spain. The study population consisted of 1,194 twin pregnancies in two herds recorded from 2010 to 2015: 522 bilateral and 672 unilateral. The presence of live twins was determined by transrectal ultrasonography between 55 and 61 days post‐AI and pregnancy confirmed 60 days later. Abortion was recorded in 278 (23.3%) cows before Day 260 of pregnancy: 7 (1.3%) in bilateral and 271 (40.3%) in unilateral twin pregnancies. Using binary logistic regression procedures the following were excluded as risk factors for abortion: herd, year, heat stress (temperature‐humidity index values >72), lactation number and right versus left side for unilateral twins. Based on odds ratios, cows carrying unilateral twins were 49.9 (right unilateral twins) and 49.3 (left unilateral twins) times more likely to suffer abortion than cows with bilateral twins. The average time of abortion for unilateral twins was 173 ± 32 days and ranged from 135 to 249 days, 43% of abortions occurring between 135 and 154 days of gestation. The authors suggest prevention or reduction of unilateral twin pregnancies by follicular puncture and drainage of subordinate follicles at AI or manual rupture of the amniotic vesicle of one of the two twins at the time of pregnancy diagnosis.  相似文献   

10.
OBJECTIVE: To examine the relationship between exposure to Neospora caninum and abortion in dairy cows during their first, second, third, and fourth or later lactations and to establish the main mode of transmission in female calves from birth until their first pregnancy was terminated by abortion or parturition. DESIGN: Prospective observational study. ANIMALS: 460 Holstein cows and 79 female calves. PROCEDURE: Cows were classified as seropositive or seronegative to N caninum within 7 days after calving; incidence of abortion was compared between groups during different lactations. Blood samples were collected from female calves before ingestion of colostrum and every 6 months until their first pregnancy was terminated by abortion or parturition; number of seropositive calves was compared between seropositive and seronegative dams. RESULTS: During the first pregnancy of their second lactation, risk of abortion for seropositive cows was 2.8 times that of seronegative cows. Among 10 calves born to seropositive cows, 4 were classified as seropositive at birth and thereafter. Among 69 calves born to seronegative cows, all were classified as seronegative at birth; 67 calves remained seronegative thereafter. CONCLUSIONS AND CLINICAL RELEVANCE: Exposure to N caninum alone was not significantly associated with abortion in cows during the first, third, and fourth or later lactations. Seropositive cows that have aborted previously may have subsequent abortions attributable to N caninum. Congenital infection was the main mode of N caninum transmission in a cohort of female calves.  相似文献   

11.
The aim of this study was to determine if the factors affecting the abortion rate in dairy herds with high incidence of Neospora‐associated abortions are different in pregnancies of cows and heifers chronically infected with Neospora caninum. In heifers (n = 229), an increase in the cumulative number of days with a mean relative humidity (RH) lower than 60% during the second trimester of gestation increases the risk of abortion. Yet, the likelihood of abortion was 7.6 times lower for pregnant heifers inseminated with Limousin bull semen, compared with those inseminated with Holstein‐Friesian bull semen. In pregnancies of parous cows (n = 521), an increase in rainfall and in the cumulative number of days with a mean RH lower than 60% during the second trimester of gestation increased the abortion rate. However, in contrast, an increase in the lactation number produced a decrease in the abortion rate, with a likelihood of abortion 4.8 times lower for pregnant cows inseminated with Limousin bull semen, and three times lower for those inseminated with Belgian Blue bull semen, compared with dairy cows inseminated with Holstein‐Friesian bull semen. Finally, the likelihood of abortion was 3.2 times lower for pregnancies of parous cows with low antibody titres against N. caninum (6–30 units) as compared to those with high antibody titres (≥30 units), whereas in heifers this variable had no effect. The practical recommendations of the present study include the control of the cow environment during the second trimester of gestation, the priority of culling for parous cows with higher antibody titres against N. caninum and the insemination of Neospora‐seropositive cows with semen from the Limousin breed.  相似文献   

12.
Breeding and production data were collected from 20 town-supply dairy herds in the Manawatu/Horowhenua region. Calving interval, calving to first service interval, first service to conception interval, inter-service interval, calving rate to first service and services per cow calving were 384, 85, 11, 43 days, 51% and 1.7, respectively, for the pooled population of 12, 056 calvings. The mean milk yield was 3730 litres per cow and the mean lactation length 291 days. Age, herd, season within year, and year, had statistically significant effects on reproductive performance, although the amount of variation due to these variables was small. The younger cows (2-year-olds) were relatively poor performers. Reproductive performance was best during the spring. Days from calving to first service, and from first service to conception, were of similar importance in determining differences in calving interval. A high incidence (25%)of return intervals of more than 49 days was found between first and second service. It was concluded from the data that a programme for breeding each cow as she comes into oestrus 46–66 days post-partum is a simple and appropriate procedure for achieving a 365-day calving interval. Such a programme is more likely to be successful if continued attention is paid to both heat-detection procedures and the nutritional requirements of animals during rearing, late pregnancy and early lactation, and if routine pregnancy testing 6 to 8 weeks after service is used to recognise the problems of post-service anoestrus.  相似文献   

13.
The possible direct relationship between climate variations and abortion in Neospora caninum‐infected cows has not been studied. The objective of this study was to determine whether climate changes could be a risk factor for abortion in N. caninum‐infected cows, and was based on yearly serological screening for neosporosis and on the confirmation of N. caninum infection on aborted fetuses in two high‐producing dairy herds with a mean 27% seroprevalence of N. caninum antibodies. The final population study was comprised of 357 pregnancies in seropositive animals. Logistic regression analysis indicated no significant effects of herd, N. caninum antibody titre, climate variables during the first and third trimesters of gestation, mean and maximum temperature–humidity index values during the second trimester of gestation, and previous abortion on the abortion rate. Based on the odds ratio, a 1‐unit increase in lactation number yielded a 0.85‐fold decrease in the abortion rate. The likelihood of abortion was 1.9 times (1/0.54) lower for pregnant cows inseminated with beef bull semen compared with Holstein‐Friesian bull semen. The likelihood of abortion decreased significant and progressively by factors of 0.5, 0.41 and 0.3 for the respective classes 40–49, 30–39 and <30 rainfall mm during the second trimester of gestation (using the class ≥60 rainfall mm as reference). As a general conclusion, it seems that increased rainfall in a dry environment can compromise the success of gestation in N. caninum‐infected cows. Attempts should therefore be made to reduce environment effects during the second trimester of gestation, a period in which the immune response of cows is diminished.  相似文献   

14.
本试验选用276头高产中国荷斯坦牛为研究对象,其中120头初产奶牛和156头经产奶牛均表现为分娩期异常或产后期异常,如难产、胎衣不下、双胎难产、早产或子宫感染。试验牛被分为处理组与对照组。处理组在产后20d间隔811连续两次皮下注射氯前列烯醇（0.4mg/次）,对照组注射4．0mL灭菌生理盐水。然后观察其首次发情的时间、适合第一次人工授精的时间、首次授精妊娠率、150d妊娠率、产后的空怀天数、重复配种奶牛的比例和每头牛的授精次数。结果表明,产后应用前列腺素对产后首次发情的时间和产后首次人工授精的时间没有影响,但处理组奶牛首次人工授精的妊娠率明显升高,这在头胎牛更为明显;产后应用氯前列烯醇可明显减少平均授精次数、缩短产后空怀时间、增加产后150d泌乳奶牛的妊娠率、降低产犊后重复配种率。  相似文献   

15.
Three-year-old Angus x Gelbvieh beef cows nutritionally managed to achieve a BCS of 4 +/- 0.07 (479.3 +/- 36.3 kg of BW) or 6 +/- 0.07 (579.6 +/- 53.1 kg of BW) at parturition were used in a 2-yr experiment (n = 36/yr) to determine the effects of prepartum energy balance and postpartum lipid supplementation on cow and calf performance. Beginning 3 d postpartum, cows within each BCS were assigned randomly to be fed hay and a low-fat control supplement or supplements with either high-linoleate cracked safflower seeds or high-oleate cracked safflower seeds until d 60 of lactation. Diets were formulated to be isonitrogenous and isocaloric, and safflower seed supplements were provided to achieve 5% of DMI as fat. Ultrasonic 12th rib fat and LM area were lower (P < 0.001) for cows in BCS 4 compared with BCS 6 cows throughout the study. Cows in BCS 4 at parturition maintained (P = 0.02) condition over the course of the study, whereas cows in BCS 6 lost condition. No differences (P = 0.44 to 0.71) were detected for milk yield, milk energy, milk fat percentage, or milk lactose percentage because of BCS; however, milk protein percentage was less (P = 0.03) for BCS 4 cows. First-service conception rates did not differ (P = 0.22) because of BCS at parturition, but overall pregnancy rate was greater (P = 0.02) in BCS 6 cows. No differences (P = 0.48 to 0.83) were detected in calf birth weight or ADG because of BCS at parturition. Dietary lipid supplementation did not influence (P = 0.23 to 0.96) cow BW change, BCS change, 12th rib fat, LM area, milk yield, milk energy, milk fat percentage, milk lactose percentage, first service conception, overall pregnancy rates, or calf performance. Although cows in BCS of 4 at parturition seemed capable of maintaining BCS during lactation, the overall decrease in pregnancy rate indicates cows should be managed to achieve a BCS >4 before parturition to improve reproductive success.  相似文献   

16.
To describe the epidemiology of cystic ovarian disease (COD), to find possible risk factors associated with the incidence of cysts and to analyse the impact of COD on the reproductive performance of dairy cows, databases from 22 dairy herds from the main dairy region in Argentina were retrospectively evaluated throughout a 3‐year period (2009–2011). A total of 248 COD cases over 9156 parturitions were recorded, resulting in a cumulative incidence rate of 2.7%. Cystic ovarian disease incidence density was lower during the first 100 days post‐partum (DPP) than during later stages of lactation. Seasonality had a significant influence on the disease presentation with higher incidence rates during winter and spring. Cows with a previous diagnosis of clinical mastitis showed 2.72 times more chances of developing ovarian cysts. Cystic cows had longer calving to first service and calving to conception intervals and lower conception rate than controls.  相似文献   

17.
The relationships between the calving to first service interval and several measures of reproductive performance were evaluated in 1738 lactation records from cows in 32 southern Ontario Holstein herds. Lactation records were divided into three mutually exclusive health categories based on the cows' postpartal disease histories.

Relationships between the calving to first service interval and the first service conception rate, number of services per conception and open interval were similar for all three health categories. The first service conception rate was lower and the average number of services per conception higher in cows first bred before 60 days when compared to cows first bred after 60 days. The relationship between the calving to first service interval and the open interval indicated that for each day that breeding was delayed the open interval was extended by 0.86 days.

It appeared that overall conception rates may be lower for cows first bred very early or very late, but differences in the overall conception rate were only significant for cows experiencing a reproductive tract infection. Unless very expensive semen is being used, it is suggested that disease free cows be bred at the first heat occurring after 40 days postpartum, and that cows experiencing postpartal disease be bred at the first heat occurring after 60 days postpartum.

  相似文献   

18.
A method for synchronization of ovulation (OVSYNCH) was evaluated for its practical use in seven North German dairy cattle herds. The original procedure of PURSLEY et al. (1995) was applied, i.e. cows were injected Gonadotropin Releasing Hormone (GnRH) at a random stage of the estrous cycle, followed by an injection of a prostaglandin F2 alpha (PGF2 alpha)-analogon seven days later and another injection of GnRH two days after PGF2 alpha. Cows were inseminated 24 h after the last injection by artificial insemination. Control animals were assigned by corresponding lactation number and stage of lactation (month of partus). Cows from the OVSYNCH group returned to the conventional reproductive management after the OVSYNCH treatment, which was the same management as that for the control group. The average milk yield in 1997 and 1998 was 8128.6 +/- 637.0 kg and 8688.3 +/- 665.0 kg per year, respectively. First service conception rate (FSC) in the OVSYNCH group (n = 187) (39.77%) was lower than in the controls (n = 175) (54.34%; P < 0.01). In 1997, FSC for the OVSYNCH group did not differ from controls (48.94% vs. 55.45%; P > 0.05), whereas in 1998, FSC for the OVSYNCH group (29.27%) was significantly lower than in the control group (29.27% vs. 52.78%) and the OVSYNCH group in 1997 (each time P < 0.01). First service conception rate of first lactation cows in the OVSYNCH group was significantly lower than in the control group (37.84% vs. 71.05%; P < 0.01), whereas no difference was found for the other lactation groups. The mean interval calving to first service was shortened in the OVSYNCH group by about 14 d as compared with the controls (P < 0.01). However, mean days open only differed by 2.92 d (P > 0.05). Proportion of cows in each class of lactation number (1., 2. and > 2. lactation number) with days open < or = 115 d in the OVSYNCH group were similar to controls (P > 0.05). There was a great influence of body condition on the success of OVSYNCH. Cows with a body condition score (BCS) of 3.00 had a significant better FSC than cows with a BCS < 3.00 (P < 0.05). First service conception rate was lower for cows with a BCS > 3.25 and < 2.75 (cows in good and poor condition taken together) than for cows with a BCS of 3.00 (P < 0.05). A positive effect of OVSYNCH was found in acyclic cows as determined by progesterone concentration in blood plasma. Nine out of eleven cows reacted with the resumption of ovarian activity. Two cows became pregnant after first insemination.  相似文献   

19.
In a study involving 7,477 pregnant cows (5,426 Holstein-Friesians and 2,051 Guernseys), each pregnancy was diagnosed by rectal palpation, using the membrane slip technique. Each cow was examined twice, first by a veterinary student, then by a clinician. Of the cows diagnosed pregnant, 7,058 (94.4%) calved. The embryonic death rate in cows examined during the first 50 days of gestation was significantly (P less than 0.001) greater than that associated with examinations after 50 days of gestation. A significant difference was found between herds in different years (P less than 0.05). There was no conclusive indication that embryonic loss at the time of or shortly after early examination was iatrogenic abortion resulting from the membrane slip technique.  相似文献   

20.
The reproductive performance of Holstein x Lai Sind crossbred dairy heifers and cows was evaluated at smallholdings in Ho Chi Minh City (HCMC). The data of 232 heifers and 244 cows (261 lactations) from 35 small dairy farms was collected over a 2-year period, from 2013 to 2014. The overall mean for age at first service (AFS), days between first and last service (DFLS), and age at conception (AC) of heifers was 479 (±80), 38 (±80), and 517 (±114) days, respectively. Average number of services per conception (NSC), conception rate (CR), and conception rate at first service (CRFS) was 1.8 (±1.4), 55, and 58%, respectively. The overall mean for the waiting period (WP), DFLS, and days open (DO) of cows was 109 (±52), 133 (±114), and 242 (±129) days, respectively. The mean for NSC, CR, and CRFS was 4.3 (±2.7), 23, and 14%, respectively. A very significant decrease in AFS and AC according to the year of birth, and a significant increase in AFS according to body weight at first insemination (>320 kg) were observed. The CRFS of heifers inseminated in 2013 was significantly higher than in 2014. Monthly mean CR in heifers and cows was negatively correlated with THI. The WP, DFLS, DO, and NSC of cows significantly decreased according to the year of calving. Cows that calved in rainy season had a significantly longer WP than in dry season. The occurrence of postpartum (PP) diseases was accompanied by an increase in WP, DO, and NSC. A decrease in body condition score (BCS) between calving and 60th day (C60) and also between 60th and 120th day of lactation resulted in a significant increase in WP and DO. A decrease in BCS between C60 was also accompanied by a considerable reduction in CRFS of cows. Season and BCS at insemination had a significant effect on NSC and CR of cows. Reproductive performance was satisfactory for heifers, but poor for cows. Losses of BCS during the first months of lactation and at insemination were the major risk factors for this poor performance. Moreover, the season had a more negative effect on fertility in cows than in heifers.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号