Effects of milk fever, ketosis, and lameness on milk yield in dairy cows

Effect of pathogen-specific clinical mastitis on milk yield in dairy cows

Our objective was to estimate the effects of the first occurrence of pathogen-specific clinical mastitis (CM) on milk yield in 3071 dairy cows in 2 New York State farms. The pathogens studied were Streptococcus spp.,Staphylococcus aureus, Staphylococcus spp., Escherichia coli, Klebsiella spp., Arcanobacterium pyogenes, other pathogens grouped together, and "no pathogen isolated." Data were collected from October 1999 to July 2001. Milk samples were collected from cows showing signs of CM and were sent to the Quality Milk Production Services laboratory at Cornell University for microbiological culture. The SAS statistical procedure PROC MIXED, with an autoregressive covariance structure, was used to quantify the effect of CM and several other control variables (herd, calving season, parity, month of lactation, J-5 vaccination status, and other diseases) on weekly milk yield. Separate models were fitted for primipara and multipara, because of the different shapes of their lactation curves. To observe effects of mastitis, milk weights were divided into several periods both pre- and postdiagnosis, according to when they were measured in relation to disease occurrence. Another category contained cows without the type of CM being modeled. Because all pathogens were modeled simultaneously, a control cow was one without CM. Among primipara, Staph. aureus, E. coli, Klebsiella spp., and "no pathogen isolated" caused the greatest losses. Milk yield generally began to drop 1 or 2 wk before diagnosis; the greatest loss occurred immediately following diagnosis. Mastitic cows often never recovered their potential yield. Among older cows, Streptococcus spp., Staph. aureus, A. pyogenes, E. coli, and Klebsiella spp. caused the most significant losses. Many multipara that developed CM were actually higher producers before diagnosis than their nonmastitic herd-mates. As in primipara, milk yield in multipara often began to decline shortly before diagnosis; the greatest loss occurred immediately following diagnosis. Milk loss persisted until at least 70 d after diagnosis for Streptococcus spp., Klebsiella spp., and A. pyogenes. The tendency for higher producing cows to contract CM may mask its impact on cow health and production. These findings provide dairy producers with more information on which pathogen-specific CM cases should receive treatment and how to manage these cows, thereby reducing CM impact on cow well being and profitability.

Effect of Lameness on Culling in Dairy Cows

The purpose of this study was to assess the effect of lameness on dairy cow survival. Cox's proportional hazards regression models were fitted to single-lactation data from 2520 cows in 2 New York State dairy herds. Models were controlled for the time-independent effects of parity, projected milk yield, and calving season, and for the time-dependent effects of lameness and culling. Other common diseases were found to be nonconfounding and so were not included in any of the final models. Survival was measured as the time from calving until death or sale. Cows were censored if they reached the start of the next lactation or end of the study, whichever occurred first. All models were stratified by herd. For all lameness diagnoses combined, survival in the herd decreased for those cows becoming lame during the first half of lactation, with a hazard ratio of up to 2 times that of a nonlame cow. Foot rot diagnosed during the second or third months of lactation decreased survival during the same time period (hazard ratio=5.1; 95% confidence interval=1.6 to 16.2). Sole ulcers diagnosed in the first 4 mo of lactation decreased survival in several subsequent periods in which the strongest association was between diagnosis in the third and fourth months of lactation and exit from the herd during that same period (hazard ratio=2.7; 95% confidence interval=1.3 to 6.0). Foot warts were not associated with decreased survival in this analysis. Lameness was never associated with increased survival in any of the models.

Using activity and milk yield as predictors of fresh cow disorders

The objective was to determine whether daily walking activity and milk yields could be used as predictors of metabolic and digestive disorders early in lactation. Data were collected from 1996 through 1999 from 1445 dairy cows in 3 Florida herds. Walking activity, milk yield, and other measures were collected from a computerized dairy management system. Mixed models analysis was used for data on cows before their first detected estrus, as identified by difference in activity. Healthy cows were defined as those without any metabolic or digestive disorder during the prebreeding stage, whereas a sick cow had an occurrence of those disorders at any time during the prebreeding stage. Metabolic disorders were ketosis, retained placenta, and milk fever. Digestive disorders included displaced abomasum, indigestion, reduced feed intake, traumatic gastritis, acidosis, and bloat. Data from cows with known cases of ketosis, left displaced abomasum, and digestive disorders were analyzed to determine changes in activity and milk yield before those specific disorders were clinically diagnosed. Although walking activity was generally lower among sick cows, cows with ketosis, left displaced abomasum, and digestive disorders had higher than average activity 8, 9, and 8 d, respectively, before each diagnosed disorder. Daily milk yields of sick cows were approximately 15 kg/d less than milk yields of healthy cows. Milk yields were lower by 6, 7, and 5 d, respectively, before diagnoses of ketosis, left displaced abomasum, and digestive disorders. Cows with ketosis, left displaced abomasum, and general digestive disorders could possibly be detected about 5 to 6 d earlier than clinical diagnoses based on changes in daily walking activity and milk yield.

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.

Optimizing replacement of dairy cows: modeling the effects of diseases

We modified an existing dairy management decision model by including economically important dairy cattle diseases, and illustrated how their inclusion changed culling recommendations. Nine common diseases having treatment and veterinary costs, and affecting milk yield, fertility and survival, were considered important in the culling decision process. A sequence of stages was established during which diseases were considered significant: mastitis and lameness, any time during lactation; dystocia, milk fever and retained placenta, 0-4 days of lactation; displaced abomasum, 5-30 days; ketosis and metritis, 5-60 days; and cystic ovaries, 61-120 days. Some diseases were risk factors for others. Baseline incidences and disease effects were obtained from the literature. The effects of various disease combinations on milk yield, fertility, survival and economics were estimated. Adding diseases into the model did not increase voluntary or total culling rate. However, diseased animals were recommended for culling much more than healthy cows, regardless of parity or production level. Cows in the highest production level were not recommended for culling even if they contracted a disease. The annuity per cow decreased and herdlife increased when diseases were in the model. Higher replacement cost also increased herdlife and decreased when diseases were in the model. Higher replacement cost also increased herdlife and decreased the annuity and voluntary culling rate.

Prevalence of lameness among dairy cattle in Wisconsin as a function of housing type and stall surface

OBJECTIVE

To determine the prevalence of lameness as a function of season (summer vs winter), housing type (free stalls vs tie stalls), and stall surface (sand vs any other surface) among lactating dairy cows in Wisconsin.

DESIGN

Epidemiologic survey.

ANIMALS

3,621 lactating dairy cows in 30 herds.

PROCEDURE

Herds were visited once during the summer and once during the winter, and a locomotion score ranging from 1 (no gait abnormality) to 4 (severe lameness) was assigned to all lactating cows. Cows with a score of 3 or 4 were considered to be clinically lame.

RESULTS

Mean +/- SD herd lameness prevalence was 21.1 +/- 10.5% during the summer and 23.9 +/- 10.7% during the winter; these values were significantly different. During the winter, mean prevalence of lameness in free-stall herds with non-sand stall surfaces (33.7%) was significantly higher than prevalences in free-stall herds with sand stall surfaces (21.2%), tie-stall herds with non-sand stall surfaces (21.7%), and tie-stall herds with sand stall surfaces (12.1%).

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that the prevalence of lameness among dairy cattle in Wisconsin is higher than previously thought and that lameness prevalence is associated with season, housing type, and stall surface.

Effect of calcium-energy supplements on calving-related disorders, fertility and milk yield during the transition period in cows fed anionic diets

The objective of this study was to determine the effect of a calcium-energy supplement at calving on the incidence of calving-related disorders (CRD), fertility, BCS and milk yield in cows fed anionic diets and to establish any associations among outcome variables. In Florida, from October to December 1997, 479 cows were assigned to three groups and treated at calving as follows: Group 1: 160 nontreated cows; Group 2: 158 cows, treated orally with 60g Ca as CaCl2; Group 3: 161 cows, treated orally with 110g Ca as calcium propionate (510g) plus propylene glycol (400g). No treatment effect was detected for any of the outcome variables. An association was found between dystocia and age and retained fetal membranes (RFM). Age and RFM were associated with metritis. RFM and displacement of the abomasum were associated with ketosis. Ketosis and age were related to displacement of the abomasum. Parity, BCS, ovarian cysts, RFM and metritis were associated with fertility.

A stochastic model simulating milk fever in a dairy herd

A simulation model was developed to evaluate the long-term effect of control strategies against milk fever (MF); here, we present the base model and sensitivity analyses. The representation of the within-herd dynamics was based on the existing SimHerd II model. Because of the relationships between MF and other diseases, the new model (called "SimHerd III") includes diseases common in a dairy herd. The cow level risk factors modelled were: base risk in the herd, parity, milk-yield potential, lactational disease recurrence, disease interrelationships, body condition and season. The diseases include clinical cases of MF, dystocia, downer-cow syndrome, retained placenta, metritis, displaced abomasum, ketosis and mastitis. The effects of diseases were represented by daily milk yield, daily body weight, daily feed intake, risk of stillbirth, conception probability, decision on culling, death and immediate removal. Simulated technical results showed that the herd effects of reduced risk of MF differed according to the reproductive efficiency in the herd. These interactions between reproduction efficiency and the effect of reduced base risk of MF were related to differences in how the simulated herds reacted to the reduction in replacements caused by MF. In the sensitivity analysis, eight potential key parameters were changed to their lowest and highest expected values retrieved from the literature. When measuring the sensitivity on milk production in the herd (as the economically most important technical effect), the model seemed most sensitive to the uncertainty of effect of MF on death risk and MF-recurrence risk.

The association between lameness, ovarian cysts and fertility in lactating dairy cows

The objective of this observational study was to evaluate the association between lameness, ovarian cysts, and fertility in lactating dairy cows. Data analysis of historical records from a 3000 Holstein farm was conducted. Sixty-five cows that became lame within 30 days postpartum were used as cases, and 130 nonlame cows served as controls. The outcome variables were incidence of ovarian cysts (OC, %), conception rate at first service (CRFS, %), overall pregnancy rate (PR, %), and calving to first service interval (CFSI, day), Incidence of OC and CRFS were analyzed by logistic regression, PR by survival analysis and CFSI by ANOVA. Lame cows had a lower CRFS (17.5% versus 42.6%) and higher incidence of OC (25.0% versus 11.1%) than controls (P<or=0.05). Calving to first service interval was not different between lame and control cows (P>0.05). There was a multicollinearity relationship between lameness and ovarian cysts. The results show that cows that became lame within the first 30 days postpartum were associated with a higher incidence of ovarian cysts, a lower likelihood of pregnancy, and lower fertility than control cows. Because this is an observational study it is not possible to conclude a cause-effect relationship.

Use of threshold serum and milk ketone concentrations to identify risk for ketosis and endometritis in high-yielding dairy cows

OBJECTIVE

To use threshold concentrations of acetone and beta-hydroxybutyrate in milk and serum, respectively; identify risk for ketosis and endometritis; and assess analyses of blood and milk samples as predictors of risk for ketosis in high-yielding dairy cows.

ANIMALS

90 multiparous Holstein cows.

PROCEDURE

At intervals before and after parturition, blood samples were obtained for determination of glucose, nonesterified fatty acids, leptin, insulin, insulin-like growth factor-1, and beta-hydroxybutyrate concentrations. Samples of milk were obtained at similar intervals after parturition for determination of fat content and concentrations of acetone, protein, and lactose. Reproductive examination of each cow was performed weekly.

RESULTS

For each cow, threshold concentrations of acetone and beta-hydroxybutyrate were calculated as 75th and 90th percentiles of maximum postpartum concentrations of acetone in milk (0.40 and 0.87 mmol/L) and beta-hydroxybutyrate in serum (2.30 and 3.51 mmol/L). Significant decrease in milk production (442 to 654 kg of energy-corrected milk/305-day period per cow) was associated with acetone or beta-hydroxybutyrate in excess of threshold values. Milk acetone concentrations > 0.40 mmol/L were associated with 3.2 times higher risk for endometritis. Low plasma glucose, high serum beta-hydroxybutyrate, and high milk acetone concentrations during week 1 after parturition were indicators of increased risk for ketosis later during lactation.

CONCLUSIONS AND CLINICAL RELEVANCE

Determination of milk acetone concentration during the week after parturition may identify cows at risk for ketosis and endometritis; with appropriate interventions, development of disease and production losses may be reduced.

Animal and dietary factors affecting feed intake during the prefresh transition period in Holsteins

Parity, body condition score (BCS), and dry matter intake (DMI) data of 699 Holsteins fed 49 different diets during the final 3 wk of gestation (prefresh transition period) were compiled from 16 experiments conducted at eight universities. The objectives of this study were to determine the effects of animal and dietary factors on DMI and to elucidate interactions between animal and dietary factors and among dietary factors on DMI during the prefresh transition period. Animal factors examined were parity and BCS, whereas dietary factors examined were rumen undegradable protein (RUP), rumen degradable protein (RDP), neutral detergent fiber (NDF), and ether extract (EE). DMI decreased 32% during the final 3 wk of gestation, and 89% of that decline occurred during the final week of gestation. Day of gestation, animal factors, and dietary factors accounted for 56.1, 19.7, and 24.2% of explained variation in DMI, respectively, and R2 of this linear multivariable model was 0.18. Cows had higher DMI than heifers. DMI decreased linearly as BCS, RUP, and NDF increased, decreased quadratically as EE increased, and increased quadratically as RDP increased. Moreover, the magnitude of DMI depression as animals approached parturition was affected by characteristics of animals and dietary nutrient composition. There were significant parity x EE, BCS x NDF, RUP x NDF, RDP x NDF, NDF x EE, and RUP x EE interactions on DMI. In conclusion, parity, BCS, and concentrations of organic macronutrients in diets affected DMI during the prefresh transition period, and the magnitude of DMI depression as animals approached parturition.

Effect of lameness on milk yield in dairy cows

OBJECTIVE

To examine the relationship between lameness and milk yield in dairy cows.

DESIGN

Cohort study.

ANIMALS

531 dairy cows.

PROCEDURE

Cows affected with lameness were classified into 1 of 3 groups on the basis of type of diseases or lesions observed, including interdigital phlegmon (foot rot), papillomatous digital dermatitis (foot warts), or claw lesions. Cows not affected with lameness were classified as healthy. From Dairy Herd Improvement Association records, 305-day mature equivalent milk yield data were collected at the end of lactation or when the cow left the herd. Milk yield was compared between cows affected with lameness and healthy cows.

RESULTS

167 (31%) cows were affected with lameness during lactation. Lame cows had claw lesions (60%), papillomatous digital dermatitis (31%), or interdigital phlegmon (9%). Milk yield in lame cows with interdigital phlegmon (mean, 17,122 lb) was significantly less, compared with healthy cows (19,007 lb).

CONCLUSIONS AND CLINICAL RELEVANCE

In this herd, interdigital phlegmon was associated with a 10% decrease in milk production. Lame cows with claw lesions or papillomatous digital dermatitis produced less milk than healthy cows, but the difference was not significant.

The effect of lameness on milk production in dairy cows

Data were collected prospectively for 1.5 yr on two New York dairy farms to investigate the effect of lameness on milk production. The numbers of study cows (percentages treated at least once for lameness) in each herd were 1796 (52%) and 724 (40%), respectively. Lame cows were identified and treated by farm employees or a professional hoof trimmer. Weekly averages of total milk production per day were recorded based on automated milk weight measurements at each milking. The effect of lameness on milk production was analyzed separately for each herd using repeated measures ANOVA. In both herds, milk production decreased significantly for cows diagnosed lame. Milk production was 1.5 kg/d lower > or = 2 wk after lameness compared with cows that had not yet been diagnosed lame in the current lactation in the larger herd. In the second herd, milk production of lame cows was 0.8 kg/d lower in the first and second wk after lameness and 0.5 kg/d lower > or = 3 wk after diagnosis. The decrease in milk production associated with lameness was larger for cows in second or greater lactation and for more severe cases. In one herd, the decrease in milk production was greater for cows with sole ulcers or foot abscesses than for foot rot or foot warts. Cows with abscesses or foot rot tended to have larger decreases in milk production in the other herd. The inconsistent results between farms may have resulted from differences in the relative frequencies of specific causes of lameness in the two herds and in the way lame cows were identified and defined for the study.

The relationship between milk yield and the incidence of some diseases in dairy cows

Logistic regression models were used to examine the relationship between milk yield and incidence of certain disorders. Lactations (n = 2197) of 1074 Holstein-Friesian cows from 10 dairies (25 to 146 cows per dairy) in Lower Saxony were studied. The 305-d yield from the previous and current lactations served as the standards for milk yield. Eight disorder complexes were considered: retained placenta, metritis, ovarian cysts, mastitis, claw diseases, milk fever, ketosis, and displaced abomasum. Each disorder complex was modeled separately. In addition to milk yield, the influences of the lactation number, the calving season and the other disorder complexes were examined with the "herd" factor taken into account. A correlation between retained placenta, mastitis, and milk fever to milk yield during the previous lactation was found to be probable and for ketosis and displaced abomasum such a correlation was found to be possible. A connection to the yield in the current lactation was shown for ovarian cysts, claw diseases, and milk fever. No relationship to milk yield existed for metritis. An influence of the lactation number was also demonstrated in various models. Single models allowed a demonstration of the influences of both milk yield and lactation number. Limitations of the model types are discussed.

Effect of lameness on the calving-to-conception interval in dairy cows

OBJECTIVE

To examine the relationship between lameness and the duration of the interval from calving to subsequent conception in lactating dairy cows.

DESIGN

Cohort study.

ANIMALS

837 dairy cows.

PROCEDURE

Cows affected with lameness were classified into 1 of 4 groups on the basis of types of disease or lesions observed, including foot rot, papillomatous digital dermatitis, claw lesions, or multiple lesions. Cows not affected with lameness were classified as healthy. Time from calving to conception was compared between lame cows and healthy cows.

RESULTS

254 (30%) cows were affected with lameness during lactation. Most lame cows (59%) had claw lesions. Lame cows with claw lesions were 0.52 times as likely to conceive as healthy cows. Median time to conception was 40 days longer in lame cows with claw lesions, compared with healthy cows. Number of breedings per conception for lame cows with claw lesions was significantly higher than that for healthy cows.

CONCLUSION AND CLINICAL RELEVANCE

Claw lesions were the most important cause of lameness, impairing reproductive performance in dairy cows, as indicated by a higher incidence of affected cows and a greater time from calving to conception and a higher number of breedings required per conception, compared with healthy cows.

Short communication: associations between blood calcium status at calving and milk yield in dairy cows

The purpose of the present study was to estimate the effect of total blood plasma calcium (TBPCC) concentration at calving on milk yield in dairy cows. Data originated from 153 dairy cows in 27 herds from a single veterinary practice. For each cow, data included calcium concentration in a blood sample taken within 12 h postpartum, monthly test-day milk yield until 300 d in milk, calving date, parity, breed, and herd. The TBPCC ranged from 0.69 to 2.73 mmol/L, with a mean value of 1.80 mmol/L. The statistical analysis adjusted for the fixed effects of parity and lactation stage, random effects of herd and cow, and the correlation between repeated measures of test-day milk yield. The results showed that TBPCC at calving was not significantly related to fat- and protein-corrected milk yield at any lactation period. The present study indicates that hypocalcemia (low TBPCC) at calving is not an important risk factor for decreased milk yield.

ADSA Foundation Scholar Award. Biology of dairy cows during the transition period: the final frontier?

The transition period, from 3 wk before to 3 wk after parturition, is critically important to health, production, and profitability of dairy cows. Most health disorders occur during this time. Compared with other stages of the lactation cycle, relatively little is known about fundamental biological processes during the transition period. The regulation and coordination of lipid metabolism among adipose tissue, liver, gut, and mammary gland are key components of the adaptations to lactation. Lipid accumulation in liver may contribute to health disorders and decreased milk production. Knowledge of key control points in hepatic metabolism of long-chain fatty acids is lacking, as is an understanding of the metabolic effects of hormones, growth factors, and cytokines that mediate stress. Recent evidence indicates that supplemental fats or restricted intakes before parturition can induce a coordinated set of metabolic changes in metabolism of long-chain fatty acids, including peroxisomal beta-oxidation, perhaps mediated by peroxisome proliferator-activated receptors. Estimates of the mixture of fuels constituting metabolizable energy in cows during the early postpartum period suggest that supply of amino acids and glucogenic compounds may be under proposed optima, whereas ketogenic and lipogenic compounds and long-chain fatty acids may be in excess. Because dietary fat does not suppress body lipid mobilization, during the early postpartum period supplemental fat may further imbalance the mixture of fuels and lead to decreased dry matter intake. Increased understanding of the biology of the transition period should decrease health problems and increase profitability of dairy cows.