Cumulative Milk Production Research Articles

163 EFFECT OF PUERPERAL METRITIS ON REPRODUCTIVE AND PRODUCTIVE PERFORMANCE IN DAIRY COWS IN ARGENTINA

The objectives of this study were to evaluate the reproductive and productive performance of dairy cows with and without puerperal metritis and to evaluate the effectiveness of using a long-acting antibiotic (200 mg mL–1 ceftiofur, Excede, Pfizer Animal Health, New York, NY, USA). Dairy cows in one dairy farm calving from July 2009 to January 2010 were examined between 3 and 14 days postpartum and classified based on vaginal discharge into 3 groups: cows with normal discharge (control); cows with purulent or red-brown vaginal discharge without foul smell, and cows with purulent or red-brown vaginal discharge with foul smell (Sheldon et al. 2006 Theriogenology 65, 1516–1530). Cows in the first 2 groups were not treated, whereas those in the third group were randomly allocated to receive 1 mL/30 kg of body weight of Excede subcutaneously behind the ear or remain untreated. From the 640 cows examined, 372 (58.2%) had normal discharge, 86 (13.4%) had a discharge without foul smell and 182 (28.4%) had a discharge with foul smell. Kaplan-Meier survival curves were obtained to compare pregnancy rates across days postpartum, and differences between curves were tested with the log rank statistic. Proportional hazards regression with PROC PHREG Cox of SAS were done to estimate the risk of pregnancy in terms of treatment, parity (first parity or ≥2 parities), type of delivery (normal or assisted), and milk production. Finally, lactation curves were modeled using SAS PROC NLMIXED to estimate the cumulative milk production at 305 days. Survival curves differed between cows in the control group and those with foul-smell discharge that were not treated (P < 0.01) and between untreated versus treated cows (P < 0.01) in the latter group. Survival curves of cows with discharge but without foul smell were intermediate and did not differ from those in the control group (P = 0.2) and those with foul smell discharge and treated (P = 0.1), but tended to be different from those with foul smell discharge and not treated (P = 0.056). The postpartum interval to achieve a 25% pregnancy rate was 72 days for cows in the control group, 73 days for cows with foul smell and treated, 83 days for cows with discharge without foul smell, and 95 days for those with foul smell and not treated. The chance of pregnancy in cows in the control group was 1.98 times higher (95% CI = 1.33, 3.08) and in cows with foul smell and treated was 2.16 times higher (95% CI = 1.37, 3.50) than those with foul smell and not treated. Finally, the chance of pregnancy in cows with discharge but without a foul smell tended to be higher (P = 0.08) than those with foul smell that were not treated, but did not differ with the other 2 groups. Parity, type of delivery, and production level did not affect pregnancy rates. Cumulative 305-day milk production was higher (P < 0.01) in control cows than those with vaginal discharge, regardless of smell and regardless of treatment. It is concluded that puerperal metritis affects the reproductive and productive performance of dairy cows, and the treatment with Excede was effective in reducing the adverse effects on reproductive performance.

Use of individual cow milk recording data at the start of lactation to predict the calving to conception interval

Milk recording data collected in 2,128 dairy herds in England and Wales between 2004 and 2006 were used to predict the calving to conception intervals. The average cumulative milk production was 8,200kg. Conception (or not) within 5 intervals measured in days (20 to 60 d, 61 to 81 d, 82 to 102 d, 103 to 123 d, 124 to 144 d) was modeled as a function of milk yields and milk constituents at the start of lactation using multilevel discrete-time survival models. Milk yield, weight and percentage of fat, protein, and lactose, and somatic cell counts on the first 2 test-days of lactation were corrected for either stage of lactation alone or stage of lactation and time of year. Five hundred and 1,628 herds, respectively, were used for parameter estimation and cross-validation. Covariates were retained in the final model if their coefficient was at least twice its standard error and their inclusion resulted in a decrease in the deviance. Overall, 73% of cows recalved. The percentage of cows that had conceived by d 20, 61, 82, 103, 124, and 145 were 0.5, 7.3, 17.9, 29.3, 38.7, and 46, respectively. The probability of conception before 145 d in milk increased with lower milk production on the second test-day, higher percentage of protein on the second test-day, and higher percentage of lactose on the first test-day. Positive associations were of a limited magnitude but nonetheless significant with the percentage of protein on the first test-day, the percentage of butterfat on the first test-day, and somatic cell count on both test-days. The model predicted the probability of conception in the cross validation data set very well. Despite the common use of fat to protein ratio as a measure of energy balance, this parameter exhibited wide variation with stage of lactation and time of the year and had a much-reduced ability to predict an early conception compared with other combinations of milk quantity and constituents.

Extended lactations in a seasonal-calving pastoral system of production to modulate the effects of reproductive failure

This study was conducted to determine whether extending the calving interval (CI) to 24 mo would be an alternative to culling and replacing cows that had failed to become pregnant. Forty-six nonpregnant lactating cows were assembled in November 2004 and assigned to receive either 3kg (low) or 6kg (high) of concentrate supplement and a basal diet of grass silage and maize silage over the winter period (13 wk). Cows returned to pasture in late March and received 1kg of concentrate/d until dry-off (milk yield <5 kg/d). Cumulative milk production was calculated from calving to the end of November 2004 (12-mo CI) and from the start of December 2004 until dry off in 2005 (extended lactation part of 24-mo CI). High winter feeding resulted in greater milk production over the winter confinement (20.0±0.3 vs. 17.8±0.3 kg/d for high and low winter feeding, respectively) and had a carryover effect during the remainder of the 24-mo CI period (5,177 vs. 4,686kg; SEM=173kg). At the end of the study, cows were ranked on cumulative milk solids and separated into 3 groups (R1, R2, and R3). During the 24-mo CI, milk yields were 7,287, 6,267, and 5,273kg (SEM=308kg) in yr 1, and 5,738, 4,836, and 4,266 (SEM=241kg) in yr 2 for R1, R2, and R3, respectively. Eighty-five percent of the cows became pregnant during the breeding season of yr 2, with a conception rate to first service of 52%. An economic analysis of different ranks with a 12-mo CI, a 24-mo CI, and an annualized herd effect, which compared an efficient spring calving system with 30% recycled cows in R1 and 10% recycled cows in R3, was carried out. Farm profit was reduced by 60% and 65% at a milk price of 22.3 euro-cents (c)/L with the corresponding values of 17% and 30% for a milk price of 30 c/L, respectively, when R1 and R3 systems were compared with an efficient spring milk (12-mo CI) production system. Within a spring system where 30% and 10% of R1 and R3 animals were subjected to extended lactations, the profit difference was reduced compared with an efficient spring system, The results indicated that lactations with a 24-mo CI may be a viable alternative to culling nonpregnant cows and be economically more suited to higher producing cows.

Long-Term Infusions of Ghrelin and Obestatin in Early Lactation Dairy Cows

Ghrelin is an endogenous ligand of the growth hormone secretagogue receptor and a potential orexigenic agent in monogastrics and ruminants. Obestatin has been reported to have the opposite (anorexigenic) effect. Fifty one multiparous cows were randomly allocated to 1 of 3 groups (n=17): a control group and 2 groups with cows continuously infused with 0.74μmol/d of ghrelin (GHR group) or obestatin (OBE group) subcutaneously. Infusions began 21 d in milk, and treatments continued for 8wk. Generalized linear models were used to determine the treatment effect on average daily and cumulative milk production and composition, and plasma ghrelin, growth hormone, insulin-like growth factor (IGF)-1, leptin, nonesterified fatty acids, and glucose. Mixed models, with cow included as a repeated effect, were used to determine if treatment effects differed by week postcalving for milk production, body weight, and body condition score (BCS; scale 1 to 10). Parity, breed, week of the year at calving, treatment, week postcalving, and the 2 wk preexperimental average of each measure (covariate) were included as fixed effects. Treatment did not affect dry matter intake. Cows infused with GHR lost more BCS (−0.71 units) over the 8-wk study period than the control (−0.23 BCS units) cows, and on average were thinner than cows in either of the other 2 treatments (0.2 BCS units). Consistent with the extra BCS loss in GHR cows, plasma IGF-1, glucose, and leptin concentrations were reduced and plasma nonesterified fatty acid concentrations were greater in GHR cows. Despite a numerical tendency for GHR cows to produce more milk (1,779kg) than control (1,681kg) or OBE (1,714kg) cows during the 8-wk period, milk production differences were not statistically different. However, the timing of the numerical separation of the lactation curves coincided with the significant changes in BCS, IGF-1, and leptin. Results indicate a positive effect of ghrelin infusion on lipolysis. Further research is required to determine if the numerical increase in milk production, which coincides with the increased negative energy balance, is real.

Relationship of beef sire expected progeny difference to maternal performance of crossbred daughters

Cumulative milk production of crossbred daughters of sires of several breeds was estimated using weigh-suckle-weigh procedures. Pooled-across-breed analyses were conducted to determine, in retrospect, relationships of sire EPD values for milk and total maternal value to daughter milk yield and daughter's offspring weaning weight. The pooled coefficient for regression of daughter 214-d milk yield on sire milk EPD was 13.4 kg/kg (residual correlation was .14). The overall mean estimated milk yield was 1,262 kg, suggesting that a difference in sire milk EPD of 1 kg corresponded to a difference of approximately 1% in cumulative daughter milk yield. The pooled coefficient for regression of daughter's offspring 214-d weight on sire total maternal EPD was 1.18 kg/kg (residual correlation was .17). All regression and correlation coefficient stated above were significantly greater than zero. Breeders who use sire milk and total maternal EPD values as selection tools should expect such selection to be effective, on average, but should also expect that a substantial proportion of individuals or small groups may not rank as predicted.

Fertility, production and culling following cesarean section in dairy cattle

A population-based historical cohort study design was used to investigate the effects of a cesarean section on calf mortality, fertility, milk production and culling on 35 Dutch dairy farms. The data were collected during a routine herd health and production control program. Cows undergoing a cesarean section had a higher calf mortality rate, a longer interval from first service to conception and a smaller risk for retained placenta than control cows, those with spontaneous deliveries and those with dystocias. Cumulative milk production at 100 days was lower and the risk of being culled was higher for cows with cesarean sections than for the control cows.

Effects of Rearing Diet, Age at Freshening, and Lactation Feeding System on Performance

This two-phase trial involved 83 Holstein heifers. The rearing phase consisted of two diets (alfalfa silage plus corn grain for ad libitum intake vs. corn silage plus urea for ad libitum intake) and two breeding age groups (13 vs. 16 mo). The lactation phase compared the above treatments plus two lactation feeding systems: concentrate fed individually to production versus a TMR. The heifers were assigned randomly to the rearing phase at 7 wk of age and fed their respective diets until 14 d prepartum. They were placed on preassigned lactation diets 14 d prepartum and remained on the lactation phase for 550 consecutive d.Daily gains and height at the withers were similar between forage groups during the first half of the rearing phase; in the second half, the heifers fed alfalfa silage were taller at the withers. Those fed corn silage consumed less DM and CP throughout the rearing phase and gained more BW than the heifers fed alfalfa in the latter half. There were no differences in daily gain or DMI between the breeding age groups.In the lactation phase, the group fed alfalfa for ad libitum intake consumed more DM and gave more milk during the first 90 d of lactation than heifers fed corn silage. However, after 90 d the difference in cumulative milk production was not significant. There were no differences in milk production, FCM, or DMI between breeding age groups. The cows fed concentrate consumed more DM and gave more milk during the first 90 d of lactation. By 550 d, there were no differences. Feeding high levels of corn silage can cause heifers to have lower DMI in early lactation. These differences tend to disappear during the second lactation.

Twinning in dairy cattle: A study of risk factors and effects

Twin calvings on Dutch dairy farms were studied using data collected through a routine herd health and production management program. Over a period of 6.5 yr, 381 twin calvings (762 calves) of a total of 11,951 calvings were recorded on 33 farms. The 381 twin calvings were compared with a referent group of 1,536 calvings that was randomly selected from the orginal 11,951 calvings. Risk factors for twin calvings were parity, season, herd and previous twinning. High cumulative milk production was associated with cows conceiving twins. Treatment for infertility in the preceding lactation was an equivocal risk factor. Twin calvings increased the risk of abortion, retained placenta, fertility-related treatment, as well as the number of days open and the number of inseminations per conception. Although twin calvings resulted in more calves born per dam, the number of available replacement heifers did not increase. After twin calving, cows produced slightly less milk and were culled more often than single calving cows. To adapt appropriate management practices for cows carrying twins, an early and reliable method for detecting twin pregnancies is needed.

Application of the Incomplete Gamma Function to Predict Cumulative Milk Production

The incomplete gamma function was used to generate lactation curves for a large sample of Holstein records from the Northeast Dairy Herd Improvement Association files. Curves were fitted by linear regression on the logarithmic transformation of the incomplete gamma function. Effects of month of freshening, days open, and intra- and interherd variability in cumulative yield were determined separately by linear regression for first, second, and later lactations for each parameter of the model. These predictions were used to extend partial records of milk production to 305-day equivalent. Predicted effects of parity number and season of freshening on incomplete gamma parameters b and c were used to specify shape of the lactation curve for partial records. Since most variation in lactation curves for high and low producing cows was due to variation in the equation multiplier, this parameter (A) was changed to shift the predicted curve closer to observations in the partial records. Predictions of 305-day cumulative yield from partial records by this technique had smaller root mean squares (356 to 586kg) than the test interval method with extension factors (396 to 751kg).

Effects of Days Dry and Days Open on Holstein Milk Production

Holstein lactation records from the Dairy Herd Improvement test day files of the New York Dairy Records Processing Laboratory of Cornell University were used to study genetic and environmental relationships of days dry and days open with milk production.Age and month of calving significantly influenced lenhth of dry period. Within herd heritability estimates of days dry were .15, .33, and .34 for second, third and later lactations.Within herd heritability estimates of days open were essentially zero. As the length of open period increased, cumulative milk production also increased at each successive stage of lactation. Differences of days open groups for 305-day milk yield were used to prepare adjustment factors for days open.

Environmental Influences on Regression Factors for Estimating 305-Day Production from Part Lactations

Summary Cumulative milk and fat production on test days from 11,420 Michigan DHIA-IBM records from 1953 to 1957 were used to derive regression factors for estimating 305-day production from part lactations. The data included 8,993 Holstein, 1,457 Guernsey, 651 Jersey, and 319 Brown Swiss lactations. Linear regression coefficients of total on part lactation within herd-season-lactation-age groups were used to measure the relationship between cumulative production on test day and total production for the first ten test days. Analyses of regression coefficients for the first, third, and seventh cumulative months of the Holstein data indicated season was not an important influence on the part-to-whole relationship. Visual inspection of the mean coefficients for age within lactation numbers failed to reveal where ages and parities should be separated or combined. Intra-herd factors for extending incomplete records were developed from the average regression coefficients of total on part lactations within herds, seasons, lactations, and ages for each of the nine cumulative test days. Each regression coefficient included in the average was weighted by the number of records from which it was computed. For comparison, extension factors disregarding herd, season, lactation number, and age effects also were derived. Although the differences between inter- and intra-herd factors were not tested for significance, the marked similarity between the Holstein factors suggests that herd had little or no influence on the part-to-whole relationship. Correlations between cumulative part and 305-day production ignoring herd differences were not less than 0.7 for the first month, increased steadily as the lactation progressed, and were 0.9 by the fifth test day for all breeds. These findings support data in the literature which suggest that production records of only 1 or 2 mo. are valuable guides to what a cow will produce in that lactation. Estimating 305-day production from such records would be useful in early culling and progeny testing.

Relations between Parts of Lactations and Producing Ability of Holstein Cows

Summary The relations between various parts of completed lactations of at least 243 days duration were considered in 599 lactations of 253 Holstein cows in the Iowa State College herd. Factors for estimating 305-day production from cumulative part records need to be different in first lactations and in later lactations. Average repeatabilities for single month milk and fat production and for cumulative month milk and fat production were 0.41, 0.32, 0.57, and 0.51, respectively. Average intrasire daughter-dam regressions for single month milk and fat production and for cunmlative month milk and fat production were 0.15, 0.09, 0.25, and 0.19, respectively. Genetic correlations between cumulative part and whole milk and fat production were over 0.9. Selecting on the cumulative part record would improve production nearly as much as selecting on the complete record itself, the efficiency values ranging from 0.74 to above unity.