Heifer rearing conditions affect length of productive life in Swedish dairy cows

Associations between rearing conditions and the risk of culling in dairy cows were studied by survival analysis. Data were collected from 1039 Swedish Red cows, 1029 Swedish Holsteins, and 56 cows of other milk or cross-breeds, representing all female animals born in 109 Swedish herds during 1998. Length of productive life was defined as the number of days from 1st calving to culling. The applied Weibull proportional hazards model included time-independent effects of breed, housing from 3 to 7 months of age, number of housing changes before calving, grazing before 1st calving, herd median age at 1st calving, age at 1st calving, cow housing, herd lactational incidence risk of veterinary-reported clinical mastitis, and the random effect of herd. Time-dependent effects were year, month, the interaction year by month, parity, number of breedings, pregnancy status, the interaction parity by pregnancy status, herd mean milk-production level, relative milk yield within breed-parity, and veterinary-reported clinical mastitis. The lactation was divided into six stages in which pregnancy status was assumed to be known by the farmer and culling could occur. Median productive life time in culled cows was 780 d and 14% of the records were censored due to terminated data collection. An individual calving age of 28.2–30.9 months was associated with the highest culling risk, 1.2-fold higher than calving at ≤25.3 months, whereas the risk decreased almost linearly with a higher herd median age at 1st calving. Housing in slatted pens with >7 calves from 3 to 7 months was associated with a 1.7-fold increase in risk, relative to litter pens. If a cow had changed housing system 4 times before 1st calving it increased the risk of culling 1.4 times, relative to two housing changes. These results show that rearing factors affect the productive life time of dairy cows in Swedish family operations.     

Disease frequencies in dairy cows in Sweden. VI. Tramped teat

An epidemiologic study of 11 653 episodes of tramped teat is presented and various risk factors identified.Swedish Red and White Breed (SRB) had a lower incidence than Swedish Friesian Breed (SLB). The incidence increased to reach a peak in the fifth (SRB) and fourth (SLB) parities. The incidence was highest in the month of calving and decreased throughout the lactation period. Dystocia and parturient paresis increased the risk of tramped teat in the month of calving in SRB cows. In SLB cows, parturient paresis increased the risk. Cows of both breeds with a positive history of tramped teat had an increased risk of recurrence in subsequent lactations. Loose-housed cows had a lower incidence than tied cows. A positive report of tramped teat increased the risk of removal, irrespective of mastitis status.     

Disease frequencies in dairy cows in Sweden. v. mastisis

An epidemiologic study of mastisis in dairy cows in Sweden covering 137 002 calvings and subsequent lactations is presented and various risk factors identified.

Swedish Friesian breed (SLB) had a higher incidence of mastisis than Swedish Red and White breed (SRB). The incidence was higher during the first part of lactation and increased with parity until the seventh lactation in SRB and the sixth lactation in SLB.

Dystocia, retained placenta and parturient paresis increased the risk of mastisis during the first part of lactation in SRB, and retained placenta increased the risk of mastitis during the first part of lactation in SLB. No associations between these periparturient disorders and the occurrence of mastitis in the latter part of lactation could be found. The incidence of mastitis was increased among teat-tramp-positive cows, and a positive report of mastitis increased the risk of mastitis in subsequent calvings.

The influence of environmental factors on the occurrence of mastitis was demonstrated by a higher incidence during housing as opposed to pasture, and a decreased incidence in loose-housed cows when compared to tied zero-grazing cows during the later part of lactation. During the first part of lactation, no seasonal variation could be found, and loose-housed cows had only slightly decreased incidence during this part of lactation when compared to tied zero-grazing cows.

The removal rate was increased in the mastitis-positive cow population.     

Occurrence of cystic ovaries in dairy cows in Sweden

The occurrence of cystic ovaries in dairy cows in Sweden was investigated using data on almost 390 000 individuals. Longistic regression analysis was used to assess relationships between cystic ovaries and explanatory variables. Cows of the Swedish Red and White breed (SRB) had twice as many diagnosed cystic ovaries as did Swedish Friesians (SLB), and first-parity cows had half as many cystic ovaries as older cows. The odds for cystic ovaries increased with increasing parity for SRV cows, even after second parity, but not for SLB cows. The diagnosis appeared to be made earlier during lactation in SRB and in high-parity cows. Twin calving in the present lactation and cysts in the previous lactation increased the odds. Cows calving either during months with subsequent risk periods during pasturing or during months with increasing daylight had lower odds for cystic ovaries. The odds increased with increasing milk yield in the present lactation (estimated conditionally on yield in the previous lactation), but decreased with increasing production in the previous lactation (estimated conditionally on yield in the present lactation). In SRB cows, the odds decreased with increasing herd production level.     

Culling of dairy cows. Part III. Effects of diseases, pregnancy status and milk yield on culling in Finnish Ayrshire cows

The effects of 15 diseases, pregnancy status and milk yield on culling were studied in 39 727 Finnish Ayrshire cows that calved in 1993 and were followed until culling or next calving. Survival analysis, using the Cox proportional hazards model, was performed with diseases, pregnancy status and milk yield as time-dependent covariates. Effects of parity, calving season and herd were also accounted for.

Pregnancy status was the single most influential factor affecting culling decisions, followed by milk yield. Several diseases also had a significant effect on culling, the most influential ones being mastitis, lameness, teat injuries, and milk fever. The effects of all of these factors varied according to the stage of lactation.

Milk yield had a significant effect on culling decisions, depending on the stage of lactation. At the beginning of lactation, milk production did not have any effect on culling decisions, but later on, the highest producers were at the lowest risk of being culled and the lowest producers had the highest risk. Adjusting for milk yield modified the effects of parity, most diseases and also pregnancy status on culling. Effects of parity increased after including milk yield in the model, indicating that milk yield and parity are interrelated in their effects on culling. The effects of pregnancy status also increased towards the end of lactation when milk yield was accounted for in the model. The effects of mastitis, teat injuries and lameness decreased after adjusting for milk production. These diseases lower milk yield and thus, part of their effect on culling was mediated through milk production. The effects of anestrus and ovarian cysts were mainly modified by pregnancy status, but not by milk yield. The effects of milk fever on culling increased at the beginning of lactation after including milk yield in the model. This suggests that even though cows with milk fever tend to be higher producers, it is the disease as such that triggers the culling decision early in the lactation. The changes in the effects of other diseases after adjusting for milk yield varied, depending on the disease and the stage of lactation.     

Disease frequencies in Swedish dairy cows. I. Dystocia

An epidemiologic study of dystocia incidence in Swedish dairy cows, covering approximately 140 000 calvings, is presented. Various risk factors were identified. The Swedish Friesian Breed (SLB) had a higher incidence than the Swedish Red and White Breed (SRB), and first calving number had a higher incidence than subsequent calving numbers. SLB heifers younger than 28 months when calving had a higher risk of dystocia than older heifers. SRB heifers younger than 26 months when calving had a higher risk than older heifers. An association between parturient paresis and dystocia was demonstrated. Male calves and twinning increased the risk. A reduced risk during pasture as opposed to housing for cows from tied herds was found, but no difference between incidence for cows in tied herds and cows in loose housing could be demonstrated. Previous history of dystocia increased the risk of recurrence in subsequent calvings and also the risk of being removed during lactation.     

Culling of dairy cows. Part II. Effects of diseases and reproductive performance on culling in Finnish Ayrshire cows

The effects of 15 diseases and reproductive performance on culling were studied in 39 727 Finnish Ayrshire cows that calved in 1993 and were followed until culling or next calving. Survival analysis, using the Cox proportional hazards model, was performed with diseases and pregnancy status as time-dependent covariates. Parity, calving season and herd were included as covariates in every model. The effect of the number of inseminations was also studied.

The farmer's knowledge of the cow's pregnancy status had a significant effect on culling. It varied according to the stage of lactation a cow was in; the earlier the farmer knew a cow was pregnant, the smaller was the risk of culling. If a cow had not been inseminated at all, her risk of culling was 10 times higher than if she was inseminated once. If a cow was inseminated more than once, she had a slightly lower risk of being culled than a cow inseminated only once. The effect of parity decreased when pregnancy status and number of inseminations were added to the model, indicating that part of the parity effect was accounted for by reproductive performance. Including diseases in the model with pregnancy status and the number of inseminations did not change the effects of reproductive performance on culling.

Mastitis, teat injuries and lameness had the greatest effect on culling (whether adjusted for reproductive performance or not), increasing the risk of culling, followed by anestrus, ovarian cysts and milk fever. In general, the effects of diseases decreased when reproductive performance was also accounted for in the model. When pregnancy status was included in the model, the effects of anestrus and ovarian cysts became slightly more protective, but when the number of inseminations was also considered, they became non-significant at the beginning of lactation and they increased the risk of culling at the end of lactation.

Sensitivity analysis, which was run to evaluate the effects of our censoring mechanism on the results, indicated that the censoring times (i.e., the time of next calving) were not fully independent of the event (culling) times; the effects of the diseases and pregnancy status at the very end of the lactation changed slightly from the original model.     

Disease frequencies of tied zero-grazing dairy cows and of dairy cows on pasture during summer and tied during winter

Disease frequencies of Swedish Red and White Breed (SRB) and Swedish Friesian Breed (SLB) in tied herds with zero-grazing management system and in tied herds with pasture periods are presented. Incidences are compared both with respect to season and between the two systems. Figures are given for accidents and nine different diseases.In zero-grazing cows no seasonal difference could be demonstrated except for a higher risk of ketosis and tramped teat during wintertime for SRB.Cows of both breeds kept on pasture had lower risks of dystocia, ketosis, mastitis and tramped test during this period, but an increased risk of accidents and inflammation of the hoof(s). SRB cows also had higher risks of retained placenta, parturient paresis and non-inflammatory diseases of the hoof(s) during pasture period.Comparison of year-round incidence in the two management systems revealed a higher risk of retained placenta in zero-grazing cows of both breeds and higher risk or parturient paresis in zero-grazing SRB cows. The risk of accidents was decreased in zero-grazing cows of both breeds.The relative risks of tramped teat, mastitis and diseases of the hoof(s) varied depending on the herd size distribution of the control group. Increased risk of mastitis in zero-grazing cows of both breeds and of tramped teat in zero-grazing SLB cows was found when comparing with cows from a group of mainly smaller herds with pasture feeding during summer. However, comparison with cows from a group of herds with the same herd size distribution as zero-grazing cows revealed decreased risk of tramped teat, mastitis and inflammation of the hoof(s) in zero-grazing SRB cows and decreased risk of diseases of the hoof(s) in zero-grazing SLB cows.     

Associations between use of electric cow-trainers and clinical diseases, reproductive performance and culling in Swedish dairy cattle

The aims of this follow-up study were: (a) to evaluate the role of ECT technology as a risk factor for several diseases; and (b) to determine if the effects of these diseases on cows' reproductive performance and as risk factors for culling are influenced by exposure to ECTs. Diseases considered were retained placenta, metritis, ketosis, cystic ovaries, silent heat, milk fever, clinical mastitis, and foot and leg problems. We used historical and contemporary controls (with control herds selected to match the experimental herds for size and location). Data consisted of 10264 Swedish Red and White (SRB) and 5461 Swedish Friesian (SLB) lactation records in 150 herds of which 33 used cow-trainers. Logistic regression was used to estimate the effects of parity and exposure to electric cow-trainers on the risks of diseases and the effects of diseases and exposure to electric cow-trainers on risk of culling. The least-squares procedure was used to estimate the effects of diseases on reproductive performance.

The dominant effects associated with use of electric cow-trainers were an increased risk for silent heat, clinical mastitis, ketosis and culling relative to cows in herds not using cow-trainers. Diseases had negative effects on reproductive performance and the effects were larger for cows in herds using cow-trainers. In herds using electric cow-trainers, the largest increase in the interval from first service to conception (58 days) was caused by the occurrences of silent heat, cystic ovaries and the combination of two or more diseases. Retained placenta, metritis, cystic ovaries, clinical mastitis and a combination of two or more diseases increased the risk of culling about two times relative to healthy primiparous cows with the increase being greater for cows in herds using cow-trainers. Silent heat did not increase risk of culling in control groups, but was the largest risk factor for culling in the exposed group. We concluded that exposure to electric cow-trainers increased the incidence risk of silent heat, clinical mastitis, and ketosis and changed silent heat from a neutral disease with respect to culling to a major risk factor. Finally, exposure to cow-trainers increased the general negative effect of diseases on the cows' reproductive performance and risk for culling.     

Reasons for culling in French Holstein cows

The study describes the profiles of culled cows in order to assess the possible contribution to economic losses due to health disorders. Data regarding dates of birth, final calving and culling, parity at culling, milk yield at the two first test-days of the final lactation and reason(s) for culling were collected in a 5-year survey, carried out from 1989 to 1994 in 84 commercial Holstein farms in western France. Polytomous logistic regression was used to assess the relationship between parity, calving-to-culling interval, milk yield and eight groups of primary culling reasons (i.e. udder disorders; infertility or reproductive disorders; lameness or foot/leg defects; emergency culling reasons; other health disorders; low milk yield; sales for dairy purpose; and other voluntary culling reasons). Out of a total of 5133 culled cows, the proportions of culls, for each of these groups of reasons, were 12.4, 28.4, 2.7, 3.9, 4.6, 16.7, 5.9, and 25.4%, respectively. Cows culled for udder disorders left the herd earlier in lactation and were more frequently at parities 4–6 than cows culled for voluntary reasons. In contrast, cows culled for infertility were younger and culled later within lactation. They were also higher yielding cows than those culled for other reasons. Cows culled for lameness were similar to those of the voluntarily culling group. Cows culled for emergency reasons were more frequently younger cows in early lactation. Cows culled for other health disorders left the herd early in lactation, but at a higher parity than the voluntarily culled cows. These results suggest that most of the culls related to health could be contributing to economic loss. However, special priority should be given to reduce culling for reproductive problems, which is the most costly exit reason.     

The Association Between Disease, Production and Culling in a University Dairy Herd

The impact of ten diseases of dairy cattle on milk production, calving interval and culling were studied in a university operated dairy herd. Cows with clinical mastitis, ketosis or displaced abomasum had lowered milk production. Cows with metritis, retained placenta, cystic graafian follicles or ovarian hypofunction had longer calving intervals. Cows with clinical mastitis, metritis, pneumonia or retained placenta had increased risks of culling.The relationship between disease and culling was based on the medical history of culled and nonculled cows using a case control approach. Therefore, it is likely that in many cases, the association between disease and culling is due to the impact of that disease on productivity.     

宁夏地区荷斯坦牛成母牛淘汰情况及长寿性影响因素分析

试验通过收集出生、产犊和离群的记录,探究宁夏地区荷斯坦牛成母牛的淘汰情况,分析影响该地区奶牛长寿性的因素。对15 523头荷斯坦牛的生产寿命、在群寿命和利用胎次进行描述性统计,分析淘汰时的胎次、季节和泌乳阶段的分布情况;计算生产寿命、在群寿命和利用胎次之间的表型相关,利用固定模型分析场-出生年、出生季节、牧场规模、淘汰原因和头胎产犊月龄对长寿性的影响。结果显示,宁夏地区荷斯坦牛的平均利用胎次为2.36胎,平均生产寿命为736.59 d。荷斯坦牛成母牛在产后第1个月内的淘汰风险最高,随着泌乳阶段的延长,成母牛在每个胎次内的淘汰风险均逐渐降低;随着淘汰胎次的增加,奶牛淘汰更加集中发生在产后泌乳早期;生产寿命、在群寿命和利用胎次之间存在较高的表型相关（均>0.9）,场-出生年、出生季节、牧场规模、淘汰原因和头胎产犊月龄对长寿性有显著影响（P<0.05）,春季出生和22月龄头胎产犊的奶牛长寿性表现更好。本研究初步揭示了宁夏地区荷斯坦牛成母牛的淘汰规律和长寿性的影响因素,为宁夏地区牛群选育成母牛长寿性状奠定了基础。     

宁夏地区荷斯坦牛成母牛淘汰情况及长寿性影响因素分析

试验通过收集出生、产犊和离群的记录,探究宁夏地区荷斯坦牛成母牛的淘汰情况,分析影响该地区奶牛长寿性的因素。对15523头荷斯坦牛的生产寿命、在群寿命和利用胎次进行描述性统计,分析淘汰时的胎次、季节和泌乳阶段的分布情况;计算生产寿命、在群寿命和利用胎次之间的表型相关,利用固定模型分析场-出生年、出生季节、牧场规模、淘汰原因和头胎产犊月龄对长寿性的影响。结果显示,宁夏地区荷斯坦牛的平均利用胎次为2.36胎,平均生产寿命为736.59 d。荷斯坦牛成母牛在产后第1个月内的淘汰风险最高,随着泌乳阶段的延长,成母牛在每个胎次内的淘汰风险均逐渐降低;随着淘汰胎次的增加,奶牛淘汰更加集中发生在产后泌乳早期;生产寿命、在群寿命和利用胎次之间存在较高的表型相关(均>0.9),场-出生年、出生季节、牧场规模、淘汰原因和头胎产犊月龄对长寿性有显著影响(P<0.05),春季出生和22月龄头胎产犊的奶牛长寿性表现更好。本研究初步揭示了宁夏地区荷斯坦牛成母牛的淘汰规律和长寿性的影响因素,为宁夏地区牛群选育成母牛长寿性状奠定了基础。     

Levels of oestrone sulphate during pregnancy in different breeds of cows and its possible association with retained foetal membranes.

The levels of oestrone sulphate in plasma of pregnant cows was followed from 30 days of pregnancy until parturition. The Swedish Jersey Breed (SJB) showed significantly lower levels of oestrone sulphate between 101 and 200 days of pregnancy than either the Swedish Red and White (SRB) or the Swedish Lowland Breed (SLB). No significant difference was noted between SRB and SLB. On days 141-160 of gestation the oestrone sulphate values were still below the 10 nmol/l level for the SJB while they were above this level for the SRB and the SLB, and the difference was significant. In the SJB, levels above 10 nmol/l were reached on days 161-180 of gestation. In the second part of this study the levels of oestrone sulphate were measured around parturition in SRB cows. At parturition, the levels of oestrone sulphate rose to peak values of 79.9 +/- 5.2 nmol/l and then decreased to 6.6 +/- 0.5 nmol/l on the day after calving. In one cow peak values of 66.0 nmol/l were reached 2 days prior to parturition, and subsequently dropped to 7.0 nmol/l at parturition. This cow had retained foetal membranes. A possible relationship between low oestrone sulphate levels prior to parturition and retained foetal membranes is discussed.     

Associations between health disorders of French dairy cows and early and late culling within the lactation

Data from an observational study, carried out during a 4.5 year period (1986–1990), were used to quantify the effects of health disorders on the risk of culling. The study population consisted of 47 commercial Holstein dairy herds from western France, comprising 4123 cows.

Logistic regression was used to assess the relationships between health disorders and early and late culling. Fourteen main health disorders with clinical signs and one subclinical disease were studied: abortion, periparturient accident, calving provided with assistance, digestive disorders, ketosis, locomotor disorders, mastitis, metritis, milk fever, cystic ovaries, respiratory disorders, retained placenta, teat injuries, non-traumatic udder disorders and status with respect to milk somatic cell count. Adjustments were made for year, month of calving, parity, breeding value for milk, best of the two first milk production records and reproductive performance. The possible effects of interactions among variables were also studied. The herd effect was taken into account using random effect models.

Non-traumatic udder disorders, teat injuries, milk fever and the occurrence of both ketosis and assistance at calving were significantly associated with an increased risk of being early culled (odds ratios (OR) ranging from 1.6 to 10.3). Early and late abortion, late metritis, poor peproductive performance, retained placenta, non-traumatic udder disorders within 45 days post-partum and mastitis occurring in the first 3 months of the lactation were positively associated with a late culling (OR ranging from 1.2 to 6.6). Cows with lower breeding value for milk and higher parities were high risk groups for culling. A lower level of milk production and occurrence of both reproductive disorders and poor reproductive performance were risk factors for late culling.     

Associations of sole ulcer at claw trimming with reproductive performance, udder health, milk yield, and culling in Swedish dairy cattle

The association between sole ulcer found at routine claw trimming 2–6 months after calving and reproductive, health and productive traits in the same lactation, was investigated in an observational study of 2368 dairy cows in 102 Swedish herds. The data were analysed by mixed multivariable linear-, logistic- and Poisson-regression modelling at the cow level, accounting for clustering within herd. Associations were found between sole ulcer and first-service conception risk in the first study year (OR 0.59), calving interval (2% longer), treatment for anoestrus (OR 1.61), and 305-day milk yield (479 kg ECM higher). No associations could be shown between sole ulcer and first-service conception risk in the second study year, the number of services per conception, clinical mastitis, high milk somatic-cell counts or culling.     

Disease frequencies in dairy cows in Sweden. IV. ketosis

An epidemiologic study of ketosis in dairy cows in Sweden covering approximately 125 000 calvings in 1268 herds is presented and various risk factors identified.The Swedish Red and White breed (SRB) had a higher incidence of ketosis than the Swedish Friesian breed (SLB). A positive report of parturient paresis, alone or in combination with a positive report of retained placenta increased the risk of ketosis in SRB cows. Simultaneous reports of parturient paresis and retained placenta increased the risk of ketosis in SLB cows. Tied cows of both breeds with pasture had a decreased risk during the months of pasture. The incidence of ketosis decreased with herd size, and tied zero-grazing cows had a higher incidence than loose-housed cows.Cows reported positive once for ketosis had an increased risk in subsequent calvings but no increased risk of removal during lactation.     

Milk Production in Swedish Dairy Cows Managed for Calving Intervals of 12 and 15 Months

The effects of calving intervals of 12 and 15 months on milk yield and milk composition were studied in 105 Swedish Red and White (SRB) and 46 Swedish Holstein (SLB) cows with 280 initiated lactations and 165 completed lactations (followed by another calving). The cows were divided into two groups, one early inseminated and the other late inseminated. The cows in the early group were inseminated at first oestrus 50 days after calving, aiming at a conventional 12-month calving interval, and the second group 140 days after calving, aiming at an extended calving interval of 15 months. Effects were studied by mixed-model analysis. Compared with the 12-month groups, total milk yield increased by 15-16% in the extended calving interval groups of both breeds, while fat, protein and lactose contents were slightly lower. The duration of lactation was 55-60 days longer in the 15-month than in the 12-month groups of both breeds. Given the possibility of a longer lactation, primiparous cows generally maintained their production longer than multiparous cows. SLB cows, especially those with a high peak yield, maintained their production longer than SRB cows. Average milk production per day within a calving interval tended to be slightly lower (2-5%) in both breeds when the interval was extended, owing to longer periods with low production and longer dry periods.     

Endocrine measurements and calving performance of Swedish red and white and Swedish Holstein dairy cattle with special respect to stillbirth

During 3 consecutive calving seasons, calving performance, placental characteristics and endocrine profiles of total 98 pregnancies of late pregnant Swedish Red and White (SRB) and Swedish Holstein (SLB) dairy heifers and cows, were investigated. Ninety-four singleton pregnancies and 4 sets of twins were recorded. In animals with singleton pregnancy, 8 stillbirths, 7 weak calves, 3 premature parturitions and 1 abortion were registered. In the SLB heifers, 19% of stillbirth (5/26) were observed, while 5% (2/42) were noted for the SRB heifers. One stillborn calf derived from the SRB cows and none was found from the SLB cows. In the heifers and cows delivering a normal living calf with unassisted parturition, the placentome thickness monitored by ultrasonography was constant towards the end of pregnancy. The numbers of foetal cotyledons varied individually between animals but in total, fewer cotyledons were found in the foetal membranes of the SRB animals than in the SLB animals (69 +/- 19) vs. (88 +/- 29) (p < 0.05). No morphological and numerical differences of the placentome thickness in animals delivering a stillborn or weak calf, compared to animals delivering a normal living calf, could be observed. In animals with unassisted parturition and without birth complications, the levels of progesterone (P4), PGF2alpha metabolite (PG-metabolite), cortisol, oestrone sulphate (E1SO4) and pregnancy associated glycoproteins (PAGs) were not different by breeds and parities. In animals carrying stillbirth, higher levels of E1SO4 were found in 3 SRB animals and 1 SLB heifer, whereas lower levels of E1SO4 were recorded in 3 SLB heifers during the last week of pregnancy, compared to the profiles found in animals with unassisted parturition. Additionally, the levels of PAGs remained low and constant in 1 SRB cow (delivering a stillborn calf), 1 SRB heifer (giving birth prematurely), 4 animals (carrying twins) and 1 aborting SRB cow. Our results show a very high rate of stillbirth in especially SLB heifers and deviating profiles of E1SO4 and PAGs in animals with impaired parturition were recorded.