Cow-specific risk factors for retained placenta,metritis and clinical mastitis in Holstein cows

The objective of this study was to evaluate the association between cow-specific risk factors and the lactational incidence risks of retained placenta (RP), metritis (MET) and clinical mastitis (CM) in 57,301 dairy cows on 20 large dairy herds in Iran between January 2005 and June 2009. A multivariable logistic regression model was used to identify risk factors for MET, RP and CM and quantify their odds ratio (OR). The lactational incidences of MET, RP and CM were 8%, 5.2% and 18.9%, respectively, and significant risk factors for MET were dystocia (OR = 4.32), stillbirth (OR = 6.26), RP (OR = 27.74), twin births (OR = 6.57), primiparity (OR = 1.68), calving during winter season (OR = 2.45) and male calves (OR = 2.41). Significant risk factors for RP were dystocia (OR = 3.17), stillbirth (OR = 3.18), abortion (OR = 8.46), milk fever (OR = 3.66), twin births (OR = 2.76), pluriparity (OR = 2.69), calving during winter season (OR = 1.86) and shorter gestation length of dairy cows (OR = 3.82). Also, significant risk factors for CM were RP (OR = 9.45), milk fever (OR = 12.36), pluriparity (OR = 2.83), calving during winter season (OR = 1.68) and the first months of lactation (P < 0.001)) and SCC concentrations at previous lactation (OR = 1.82). The current study indicates that differentiation can be made among cows in the risk of having MET, RP and CM based on a combination of cow factors. These differences among cows could be useful to aid the better detection of these diseases in the dairy herds.     

Calf survival and reproductive performance of Holstein–Friesian cows in central Ethiopia

This study was carried out to evaluate the reproductive performance and calves survival rate of Holstein–Friesian (HF) herd in Holeta, central highland of Ethiopia. A retrospective analysis of 26 years data was carried out, from which records of 724 age at first calving (AFC), 2,022 calving intervals (CI), 2,971 breeding efficiencies (BE), 260 abortions, 111 stillbirths were derived from 795 cows. Moreover, 738 female calves’ records were also included for survival rate study. The overall least squares means of AFC, CI, and BE were 40.9 ± 0.33 months, 475 ± 2.84 days, 81.9 ± 0.26%, respectively, while the incidence rates of abortion, stillbirth, and female calves survival rate for this herd were 8.0%, 3.4%, and 77.5%, respectively. The effects of parity number and year of birth/calving on CI and BE were significant (P < 0.001). Moreover, birth year had significant (P < 0.001) effect on AFC and calves survival rate, while calving season had significant effect on BE. The reproductive performance found in this study was lower than the performance reported in many tropical regions and the genetic potential of HF breed in their origins. Moreover, higher loss due to calf mortality was observed. Thus, the centre should consider appropriate measures to improve its herd reproductive performance and calves survival rate for attaining its aspired objectives.     

The effect of twinning on milk yield,dystocia, calf birth weight and open days in Holstein dairy cows of Iran

Calving records of Iranian Holsteins from April 1998 to September 2006 comprising 16 herds with 104 572 calving events representing 4045 twin births were used to evaluate reported open days, calving difficulties and calf birth weight in single‐ and twin‐births and the relationship exists between twinning and milk production. A logistic regression model was constructed to analyse dystocia for single‐ and twin‐births. In addition, statistical analyses of 305‐day milk yield, open days and calf birth weight were performed using the general linear models procedure. The odds of dystocia was greater after twin births [p < 0.0001; odds ratio (OR) = 2.32]. The odds of dystocia decreased from parity 1 to parity 2 and beyond (p < 0.0001; OR = 0.44). Open days were significantly different between single (129.28 days) and twin (144.88 days) births (p < 0.05). Calf birth weights were significantly greater for singletons than twins (43.33 kg vs. 34.36 kg; p < 0.05). In addition, twin‐calved cows had greater 305‐day milk production than single‐calved cows (p < 0.05). In general, development of practical management strategies to cope with the negative effects associated with twinning on dairies is critical, especially if the trend towards increased twinning in the dairy cattle population continues.     

Subclinical endometritis in Zebu x Friesian crossbred dairy cows: its risk factors,association with subclinical mastitis and effect on reproductive performance

A study was carried out on 59 clinically healthy Zebu x Friesian crossbred cows to determine the prevalence of subclinical endometritis, associated factors and its effect on the reproductive performance. Subclinical endometritis was diagnosed by endometrial cytology using uterine lavege technique and subclinical mastitis using CMT. The clinical, management and reproductive data were obtained from a weekly follow up visit of each cow for a period of 6 months after calving. The prevalence of subclinical endometritis, with ≥5% neutrophil count, was 47.5% and 30.5% at week 4 and 8, significantly decreasing (P = 0.002) as postpartum period advanced. Body condition score at week 4 postpartum (OR = 4.5, P = 0.017) and regular cow exercise (OR = 4.8, P = 0.026) were the significant risk factors while post-calving hygiene (P = 0.06) was poorly associated. Subclinical endometritis was also directly associated with subclinical mastitis at both week 4 (OR = 4.5, P = 0.012) and 8 (OR = 3.6, P = 0.031) postpartum. The risk of first service pregnancy (OR = 5.1, P = 0.004) was higher in cows negative for subclinical endometritis at week 8 postpartum and the proportion of cows that required more than 3 services was higher in cows with uterine inflammation. Also the proportion of cows diagnosed pregnant within 180 DIM was higher in cows with normal uterus at both week 4 (OR = 10.3, P = 0.001) and week 8(OR = 21.8, P = 0.001). These results indicated that subclinical endometritis was directly associated with poor body condition and subclinical mastitis and that it had negative effect on reproductive traits of dairy cows. This association may also reflect the possibility of translocation of bacteria/bacterial products from the uterus to the udder or vic-versa or else the presence of common cause for both endometritis and mastitis.     

Abortion in dairy cattle with advanced twin pregnancies: Incidence and timing

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.     

Twinning in Dairy Cattle

Twinning in dairy cattle is an unavoidable outcome of reproduction and is undesirable because it reduces the overall profitability of a dairy operation through negative effects on cows calving twins as well as on calves born as twins. Cows calving twins are at greater risk for many periparturient reproductive and metabolic disorders than nontwinning herdmates, and incidences of abortion, stillbirth, neonatal calf mortality, and reduced birth weight are greater among twin compared with singleton calves. Twinning is a complex trait with multiple causative factors, and empirical evidence supports a role for both genetic and environmental risk factors in cattle. Risk factors for twinning include genetics, season, parity, ovulation rate, and milk production. The observation that twinning has increased in the dairy cattle population over time suggests a concurrent change in one or more of these causative factors during this same period. At present, dairy farmers and their consultants are ill prepared to make sound-management decisions to mitigate the negative effects of twinning on their operations because of a lack of applied scientific data on management strategies for periparturient dairy cows carrying twin fetuses. A clear understanding of the factors responsible for twinning is essential for future development of strategies to manage twinning in dairy operations.     

A cross-sectional study of paratuberculosis in 1155 Danish dairy cows

In a cross-sectional study on milk samples from 1155 cows from 22 Danish dairy herds, selected risk factors for paratuberculosis were identified. The diagnostic procedure used was an indirect enzyme-linked immuno-sorbent assay (ELISA) to detect antibodies against Mycobacterium avium subsp. paratuberculosis. A sample was considered test-positive if it had a corrected optical density >/=0. 025 (test sensitivity 71.4% and test specificity 89.7%). Of the 1155 samples, 8.8% (102/1155) were test-positive, and 19 out of the 22 dairy herds had >/=1 test-positive cows. The significant risk factors in a multiple logistic regression analysis were: Jersey versus large breeds, high parity versus low parity, the first month after calving versus other months of lactation, and a large herd size compared to a small herd size. The highest probability (37-38%) of a positive test was observed among older cows (parity >4) and tested within the first month after calving (irrespective of breed). The lowest probability (2%) of a positive test-result was observed among first parity, large-breed cows tested before calving or later than one month after.     

Changes in colostrum of Murrah buffaloes after calving

Colostrum samples were collected from 8 Murrah buffaloes on days 1, 2, 3, 4 and 5 after calving. Levels of IgG averaged 54.0 mg/ml at calving, then decreased significantly (P < 0.01). IgA and IgM on day 1 were 3.22 mg/ml and 5.22 mg/ml, respectively; both decreased during the first five days after calving. Values of IgA and IgM were higher than those reported in cows. SCC values, which were high at calving (500 000 per ml), reduced significantly (P < 0.01) on day 2, then decreased slightly until day 5 (180 000 per ml). At calving, macrophages were the most prominent cells in buffalo colostrum, followed by lymphocytes and neutrophils. Phagocytic activity was 23% at calving and reduced significantly (P < 0.01) to 14% on day 5. Phagocytic index was highest in the first colostrum, and then decreased non-significantly.     

Genetic parameters and trends for calving interval in the first three lactations of Iranian Holsteins

Calving records from the Animal Breeding Center of Iran collected from January 1987 to December 2007 and comprising 292,875 calving events of Holsteins from 1,413 dairy herds were analyzed using univariate and bivariate linear animal models to estimate heritabilities and genetic correlations for calving intervals in the first three lactations of Holstein cows. Genetic trends were obtained by regressing yearly mean estimates of breeding values on calving year. Average calving intervals were from 406 to 414 days and decreased over the parities. Heritability estimates for calving intervals varied from 0.03 to 0.04 across the parities. Also, estimates of genetic correlations between calving intervals in different parities were high and ranged from 0.67 to 0.89. The average annual phenotypic trends obtained from fitting linear regression of annual mean calving intervals at parity 1 and 2 were significant (P < 0.01), but the phenotypic trend of calving interval at parity 3 was not significant over the years. On the other hand, there was an increasing genetic trend for calving interval at parity 1, and there were decreasing genetic trends for calving intervals at parity 2 and 3 over the years (P < 0.01). The low estimates of heritability obtained in this study imply that much of the improvement in calving interval traits could be attained by improvement of production environment rather than genetic selection.     

Seroprevalence of camel brucellosis (Camelus dromedarius) in Somaliland

The present study was delineated to investigate the prevalence and risk factors of camel brucellosis in Northern Somalia (Somaliland). The study was carried out at three main districts of camel-rearing regions of Somaliland (Awdal, Waqoyi Galbed and Togdheer) in the period from July to November, 2008. A total of 1246 camel blood sera were randomly collected from 42 sporadic small scale camel herds. Two serological tests were used to screen all serum samples, Rose Bengal Plate Test (RBPT) and indirect ELISA (I-ELISA). Multivariate logistic regression was constructed to study the risk factors associated with Brucella seropositive cases. The overall prevalence of camel brucellosis in districts under investigation was 3.9% by RBPT and 3.1% by (I-ELISA). Multivariate logistic regression on animal level showed that locality (P < 0.05; OR: 6.254; CI, 1.186–32.976), herd size (P < 0.001; OR: 5.493; CI, 2.956-10–207), rearing with other ruminants (P < 0.001; OR: 12.433; CI, 3.957–39.060), and contact with other camels (P < 0.05; OR: 5.311; CI, 1.093–25.800) were the potential risk factors. However, herd size (P < 0.05; OR: 5.425; CI, 1.181–24.932), and rearing with other ruminants (P < 0.05; OR: 20.466; CI, 1.456–28.638) were recorded as risk factors on the herd level. The results of the present investigation indicate that the Brucella spp. exists within the camel herds in Somaliland. Further studies need to be done on Brucella infection in the other ruminants to determine which measure should be followed for control of brucellosis.     

Risk factors for <Emphasis Type="Italic">Mycobacterium avium</Emphasis> subspecies <Emphasis Type="Italic">paratuberculosis</Emphasis> in Fars province (Southern Iran) dairy herds

A cross-sectional study was conducted from March to August 2006 in dairy herds in Fars province, southern Iran to determine the herd-level risk factors for infection with Mycobacterium avium subspecies paratuberculosis (MAP). Statistical analysis using multivariable logistic regression showed that contamination of udders of periparturient cows with manure (OR = 6.4, P = 0.02) and history of having suspected cases of Johne's disease in the herd (OR = 6.7, P = 0.04) were significantly associated with the herd infection status. No relationship between breed, herd size and other management practices with the infection status of the herd were found in this study. Implementing high sanitary measures in the farm, particularly with respect to manure handling and cleaning could be considered as one of the important aspects in controlling disease in the region as well as in the future educational effort.     

Longitudinal observation on reproductive and lactation performances of smallholder crossbred dairy cattle in Fitche,Oromia region,central Ethiopia

A two-year longitudinal study was conducted to assess the reproductive and lactation performances of smallholder crossbred dairy cattle in Fitche, central Ethiopia. Twenty-four smallholder dairy farms were monitored and data on reproductive, breeding, lactation and management aspects of crossbred dairy cows (n = 69) were collected and analysed. Moreover, milk samples were collected and analysed for progesterone. The overall Least-squares means for calving interval (CI), calving to conception interval (CCI) and first observed oestrus after calving were 516, 253 and 141 days, respectively. Suckling significantly prolonged these intervals. The mean first onset of luteal activity (OLA) after calving was 52 days, while 67.4% (n = 43) had a delayed (>55 days) return to cyclicity after calving. Suckling and parity number significantly (p < 0.05) influenced the OLA. The mean lactation length was 54.4 weeks. The overall daily mean milk yield for the first 43 weeks of lactation after calving was 11.7 L/day. The estimated daily milk yield increased slowly and reached peak (13.8 L/day) around the 11th week post partum and declined gradually and steadily. Suckling status, season of calving and parity number significantly influenced the estimated daily milk yield. In conclusion, the present study indicated that the smallholder crossbred dairy cows in the study area had prolonged intervals to first oestrus after calving, to conception and to the next calving, and thus their reproductive performance is unsatisfactory. Delayed first onset of luteal activity (postpartum anoestrus) contributed to these extended intervals. Further detailed investigation is suggested to examine the effects of other relevant factors on the reproductive and lactation performances of smallholder crossbred dairy cows for appropriate intervention.     

Effects of first postpartum progesterone rise,metabolites, milk yield,and body condition score on the subsequent ovarian activity and fertility in lactating Holstein dairy cows

Seventy multiparous healthy lactating Holstein cows (fat-corrected milk yield = 7,561.8 kg) were monitored from 14 days before to 70 days after calving. Transrectal ultrasound scanning was performed twice weekly from 7 to 65 days postpartum. Blood samples were also collected twice weekly to measure serum P₄ and biweekly to detect serum β-hydroxybutyrate (βHB) and nonesterified fatty acid (NEFA) concentrations. Body condition score (BCS) was taken biweekly after calving. Based on the serum P₄ profile of 59 cows (11 cows were excluded due to the occurrence of postpartum diseases) studied, 27 (45.8%) had normal ovarian activity, while 21 (35.6%), six (10.1%), three (5.1%), and two (3.4%) had delayed ovulation (DOV), prolonged luteal phase (PLP), short luteal phase (SLP), and cessation of ovarian activity, respectively. Cows with PLP had an earlier ovulation compared to that of cows with normal ovarian activity (23.16 ± 4.02 vs 31.9 ± 8.35 days; P < 0.05). PLP cows also had a greater mean ± standard deviation peak milk yield (44.2 ± 5.8 vs 37.2 ± 5.7 kg/day, 75 days postpartum; P < 0.05) than cows with normal postpartum ovarian activity. The PLP group also had greater milk production in the previous lactation period. Logistic regression analysis indicated that cows with P₄ concentration ≥1 ng/ml on day 24 after calving were more at risk for PLP by 1.1 for each 1 kg increase in mean peak milk yield during 75 days after calving. BCS was lower in cows with DOV compared to that of cows with normal ovarian activity at any time after calving (P < 0.05). Serum βHB concentrations in DOV cows were significantly higher than that of normal cows on day 42 after calving (0.69 ± 0.29 vs 0.54 ± 0.12 mmol/L, P < 0.05). No significant difference was found in the mean concentrations of NEFA between cows in different groups at any time after calving (P > 0.05). The concentrations of P₄ on days 28 and 31 were negatively correlated with βHB concentration on day 42 after calving in cows with normal ovarian activity (R = −0.44, P = 0.02). In conclusion, these findings suggest that early ovulation and hence early postpartum P₄ rise in addition to the high milk production could partly be responsible for the occurrence of PLP in dairy cows.     

Risk factors associated with cystic ovarian disease in Norwegian dairy cattle

Background

The aims of this study were to establish the incidence of cystic ovarian disease (COD) and its geographical and seasonal variation in Norway, investigate the effect of COD on culling rates, and describe the effects of COD on subsequent reproductive performance and its association to twins.

Methods

Diagnosis of COD was made by veterinary surgeons in the field. Four statistical models were made all including herd as random effect: The four different dependent variables investigated were: 1) Diagnosis of COD between 40 and 165 days in milk or not; (n = 511,657); 2) Twins or singleton; data restricted to lactations with new calving (n = 156,661): 3) Culling/removal or not (n = 573,184): 4) Culling due to reproductive problems; data included only lactations which ended in culling (n = 234,232). Model 1, 3 and 4 applied Cox regression models, and model 2 logistic regression. Independent variables were parity, twins/singletons, calving season, herd size, region, COD occurrence in present lactation (if not dependent), and COD diagnosis in previous lactation.

Results

The incidence was 0.82% per lactation. COD increased with increasing parity, was smallest at herd size between 35 and 85 cows. Cows in 1^st parity and calved in spring had lowest hazard of COD and hazard for COD diagnosis was highest in autumn with HR = 2.6 (1.9 - 3.4) compared to spring. There was an interaction between parity and season. COD incidence was lower south of 60°N. Cows which experienced COD had an increased odds of giving birth to twins OR = 2.2 (1.7 - 2.7). Of those that were culled, those with COD were culled more frequently because of reproductive problems; HR = 2.1 (1.9 - 2.3) for higher parity than 2. Having COD diagnosed in the preceding lactation was a hazard for diagnosis in the lactation studied.

Conclusion

COD diagnosis is strongly associated with season (autumn calving) and parity. Herds north of 60°N have more COD. Occurrence of COD is associated with twin births as well as culling due to reproduction.     

Milk yield and reproductive performance of dairy cattle under smallholder management system in North-eastern Amhara Region,Ethiopia

This study was conducted in South Wollo Zone of Amhara Regional State, Ethiopia, to assess the milk yield and reproductive performance of indigenous and crossbred cattle under smallholder management conditions. Questionnaire survey was used to collect retrospective data on the performance of dairy cattle in 186 households. Thirty two postpartum cows (16 indigenous and 16 crossbred) were selected purposively and monitored for five months and milk samples were collected twice per week from each cow to determine postpartum ovarian activity using ELISA techniques. Daily milk yields at all stages of lactation were significantly (P < 0.01) higher in crossbred than indigenous cows. Crossbred cows had significantly (P < 0.01) longer lactation length and shorter age at first calving, while calving interval was significantly shorter in cows that gave previous calves during the wet season than the dry season. Only six cows (18.8%) showed heat signs on an average of 136 days postpartum of which one was a crossbred and five were indigenous. While, 11 cows (34.3%) resumed ovarian activity until 150^th day postpartum among which three were crossbred and eight were indigenous.     

Dystocia in Friesian cows and its effects on postpartum reproductive performance and milk production

A total of 1,243 records for 585 dairy Friesian cows from 1997–2004 were used to study the factors affecting dystocia and its effects on reproductive performance and milk production. The overall incidence of dystocia was 6.9%. The percentage of dystocia decreased with increasing live body weight, age, and parity of cows (P < 0.05); however, it increased with increasing birth weight of calves (P < 0.05). The highest percentage of dystocia was detected in winter season, but the least percentage was in summer season (P < 0.05). The percentage of incidence of dystocia was significantly (P < 0.05) higher with winter feeding compared to summer ration (8.2% vs. 5.1%). The percentage of incidence of dystocia was significantly (P < 0.05) higher with twinning than single calving (15.5% vs. 6.5%), while not significantly affected by the sex of born calves. Incidence of dystocia had adverse effects on reproductive performance and milk yield. The service interval, service period, days open, and calving interval were significantly (P < 0.05) longer in cows afflicted with dystocia compared to normal cows. The conception rate was lower (P < 0.05), but the number of service per conception was higher (P < 0.05) in cows afflicted with dystocia compared to normal cows (60.5% vs. 73.0% and 3.4 vs. 2.7, respectively). Average daily milk yield was lower (P < 0.05) by 1 kg for cows with incidence of dystocia compared to normal cows.     

Risk factors for postpartum endometritis and the effect of endometritis on reproductive performance in dairy cows in Korea

The objectives of this study were to determine the risk factors for postpartum endometritis by evaluating several reproductive factors in individual cows, and to determine the effect of endometritis on the subsequent reproductive performance in dairy herds in Korea. The data, including health status, parity and body condition score (BCS) of cows, and calving date, were collected from 320 cows in eight dairy herds calving from January 2001 to October 2002. We used logistic regression to evaluate the effects of these factors on endometritis. A stepwise procedure, used to obtain the appropriate model with alpha=0.05, revealed that retained placenta, metabolic disorders and parity are the important risk factors for endometritis. The mean intervals from calving to first service and conception were prolonged (P<0.01) by 23 and 36 days, respectively, in the endometritis group compared to the non-endometritis group. The first service conception rate was lower (P<0.05) in the endometritis group (47.6%) than in the non-endometritis group (62.6%). The number of services per conception was higher (P<0.05) in the endometritis group (1.9) than in the non-endometritis group (1.6). We conclude that retained placenta, metabolic disorders and cow parity are strongly correlated with the development of postpartum endometritis, which decreases reproductive performance in dairy herds in Korea.     

Seroprevalence of Neospora caninum antibodies and its consequences for reproductive parameters in dairy cows from Dakar–Senegal,West Africa

The aim of this study was to determine the seroprevalence of Neospora caninum antibodies and its effects on reproductive parameters in cows in intensive dairy herds in Dakar. Randomised blood samples were taken for serology from 196 cows in four herds with a history of sporadic abortion. All of the sera were assayed for antibodies against N. caninum, Candida guillermondii, Coxiella burnetii, and Chlamydophila sp. The associations between serostatus and reproductive parameters (abortion, number of inseminations to conception, and calving to conception interval) were assessed over a period of 5 years (2004–2008). The seroprevalence of N. caninum antibodies in dairy cattle was 17.9%. The local Gobra breed and crossbreeds had higher levels of N. caninum antibodies than exotic breeds (p < 0.05). For the most recent pregnancies, seropositive cows required more inseminations to establish conception than seronegative cows (p < 0.05). The results indicate that dairy cattle from Dakar are exposed to N. caninum. Neosporosis should, therefore, be systematically considered as a cause when the calving to conception interval is prolonged.     

The association of displaced abomasum with various periparturient factors in dairy cows. A retrospective study

The associations between displaced abomasum (DA) and various factors in seven dairy herds were investigated. The overall rate of DA in 7026 calving cows was 1.7%. All cows were routinely clinically examined between 5 and 14 days post partum. DA was found, by a retrospective analysis, to be associated in terms of increased relative risk, R, with rising parity, stillbirth (R = 1.97), twins (R = 3.25), retained placenta (R = 6.62), primary metritis (R = 4.26), aciduria (R = 6.17), ketonuria (R = 33.04), and a low milk yield before calving (R = 2.29). No association was established between DA and milk fever. The significance of the associations in relation to the aetiology of the disease, with special reference to the fat cow syndrome, is discussed, and the possible role played by the ruminal acidosis associated with the various factors is investigated.