Rolling Herd Average Research Articles

Transition cow nutrition and management strategies of dairy herds in the northeastern United States: Part I—Herd description and performance characteristics

Our objective was to describe management and herd characteristics of the transition period on freestall dairy herds in the northeastern United States using an on-farm survey and prospective cohort design. Enrolled herds (n = 72) had a median of 900 milking cows (range: 345-2,900) and a rolling herd average of 12,674 kg (standard deviation ± 1,220 kg), and 87.2% (n = 82/94) of fresh pens were milked at least 3×/d. The prevalence of herds with ≥15% of sampled cows with elevated concentrations of nonesterified fatty acids prepartum (≥0.27 mmol/L, 2-14 d before parturition) and postpartum [primiparous: ≥0.60 mmol/L, multiparous: ≥0.70 mmol/L, 3-14 d in milk (DIM)], β-hydroxybutyrate postpartum (≥1.2 mmol/L, 3-14 DIM), and haptoglobin postpartum (≥1 g/L, 0-12 DIM) was 51%, 51%, 51%, and 57%, respectively. In most herds, cows were moved to a calving pen when showing signs of labor (73.6%; n = 53/72) instead of 0 to 3 d before expected calving (26.4%, n = 19/72). Cows remained in the calving or maternity pen for a median (range) time of 2 (0-24) h after parturition before moving to the next pen. Primiparous cows remained in the first pen moved to after parturition for a longer period than multiparous cows [median (range) days: 12 (1.5-25) vs. 6 (1.5-22)]. Approximately 20% of herds had routine vaccinations administered in the maternity or calving pen, first pen after parturition, or both. Almost all herds (n = 69/72) performed fresh cow health checks; however, only 53% (n = 38/72) locked up all fresh cows daily. More herds housed primiparous and multiparous cows in separate pens during the far-off dry (65.3%; n = 47/72) and high-lactation (81.9%; n = 59/72) periods compared with the close-up dry (31.9%; n = 23/72) and fresh periods (27.8%; n = 20/72). At least half of the pens observed during the far-off dry, close-up dry, and fresh periods had a stocking density <100%. Approximately one-third of pens observed during the far-off dry period had feed pushed up ≤4×/d compared with approximately 15 to 20% of pens observed during the close-up dry, fresh, and high-lactation periods. More than half of the total mixed ration samples acquired from the far-off and close-up dry period visits had greater than the recommended proportion of particles in the 19-mm screen of the Penn State Particle Separator. The results of this observational study illustrated the range of management practices used in freestall herds in this region and lay the groundwork for future hypothesis-driven studies using this sampled population.

Applying nutrition and physiology to improve reproduction in dairy cattle

The establishment and maintenance of pregnancy in lactating dairy cows is a complex biological event that is influenced by a multitude of factors, from the reproductive biology of the cow to managerial aspects of the dairy farm. It is often mentioned in the scientific literature that fertility in dairy cows has declined concurrent with major advances in milk production. Some of this decline is attributed to the negative genetic correlation between milk production and reproduction. In the United States, yearly production per cow has increased steadily at a rate of 1.3% in the last decade and it is likely that this trend will continue in the years to come. At this rate, the average cow in the United States will be producing over 14 tons of milk per year in 2050 and technologies will have to be developed to allow these cows to reproduce to maintain the sustainability of dairy production. Despite high production, it is not uncommon for dairy herds with rolling herd averages for milk yield above 11,000 kg to overcome the challenges of reproduction and obtain satisfactory reproductive performance. Among other things, those herds have been able to mitigate some of the mechanisms that suppress reproduction in dairy cows such as extended postpartum anovulatory period, poor estrous detection, low pregnancy per insemination and, to a lesser extent, the high pregnancy loss. The success of those farms comes from an integrated approach to fertility that includes adequate cow comfort, elaborated transition cow management and nutrition, aggressive postpartum health monitoring program with preventative and curative measures to mitigate the negative effects of diseases on reproduction, and a sound reproductive program that includes manipulation of the ovarian cycle to allow for increased insemination rate. More recently, introduction of fertility traits in selection programs have created new opportunities for improved reproduction without neglecting economically important production traits.

Estimating US dairy clinical disease costs with a stochastic simulation model

A farm-level stochastic model was used to estimate costs of 7 common clinical diseases in the United States: mastitis, lameness, metritis, retained placenta, left-displaced abomasum, ketosis, and hypocalcemia. The total disease costs were divided into 7 categories: veterinary and treatment, producer labor, milk loss, discarded milk, culling cost, extended days open, and on-farm death. A Monte Carlo simulation with 5,000 iterations was applied to the model to account for inherent system variation. Four types of market prices (milk, feed, slaughter, and replacement cow) and 3 herd-performance factors (rolling herd average, product of heat detection rate and conception rate, and age at first calving) were modeled stochastically. Sensitivity analyses were conducted to study the relationship between total disease costs and selected stochastic factors. In general, the disease costs in multiparous cows were greater than in primiparous cows. Left-displaced abomasum had the greatest estimated total costs in all parities ($432.48 in primiparous cows and $639.51 in multiparous cows). Cost category contributions varied for different diseases and parities. Milk production loss and treatment cost were the 2 greatest cost categories. The effect of market prices were consistent in all diseases and parities; higher milk and replacement prices increased total costs, whereas greater feed and slaughter prices decreased disease costs.

Association of bedding types with management practices and indicators of milk quality on larger Wisconsin dairy farms

The objective of this study was to identify associations of bedding type and selected management practices with bulk milk quality and productivity of larger Wisconsin dairy farms. Dairy herds (n=325) producing ≥11,340kg of milk daily were surveyed during a single farm visit. Monthly bulk milk SCC and total bacteria counts were obtained from milk buyers for 255 farms for a 2-yr period. Of farms with the same type of bedding in all pens during the study period, most used inorganic bedding (IB), followed by organic nonmanure bedding (OB) and manure products (MB). Almost all bulk milk total bacterial counts were <10,000 cfu/mL and total bacterial count was not associated with bedding type. Bulk milk somatic cell score (BMSCS) was least for farms using IB, varied seasonally, and was greatest in the summer. The BMSCS was reduced when new bedding was added to stalls at intervals greater than 1wk and when teats were dried before attaching the milking unit. The BMSCS for farms using OB was reduced when bedding in the backs of stalls was removed and replaced regularly and when fewer cows with nonfunctioning mammary quarters were present. The BMSCS for farms using MB was reduced when the proportion of cows with milk discarded was less. The rolling herd average (RHA) of herds using IB was 761 and 1,153kg greater than the RHA of herds using OB and MB, respectively. The RHA was 353kg greater on farms where farmers understood subclinical mastitis and 965kg greater on farms milking 3 times daily. Each 1% increase of cows with nonfunctioning mammary quarters was associated with a decrease of 57kg of RHA. The BMSCS, proportions of cows with milk discarded and proportion of cows with nonfunctioning mammary quarters were least for herds using IB and were associated with increased productivity. Large Wisconsin dairy farms that used inorganic bedding had greater productivity and better milk quality compared with herds using other bedding types.

Prediction of Standard Lactation Curves for Primiparous Holstein Cows by Using Corrected Regression Models

Prediction of the expected milk yield is important for the management of the primiparous cows (PPC) with a few or no data on their own milk productivity. We developed a system of regression equations for predicting milk yields in standard lactation. The models include the systematic effects of the calving season, the five-year rolling herd average of milk yield of PPC, the breeding values of the parents for milk production, and daily milk recordings. A total of 21,901 lactations of Holstein PPC were collected during the regular monthly milk recordings of cows in the Republic of Slovenia. By including daily milk recordings in the model, the coefficients of determination of regression models for the prediction of milk yield increase: without known recordings (M0) R2=0.80; with one recording (M1) R2=0.82; with two first consecutive recordings (M2) R2=0.86; and with three recordings (M3) R2=0.89. Deviations of milk yield up to 500 kg in a standard lactation (<1.6 kg/day) were as follows: with the model M0, they occurred in 53.4% of PPC; with M1, they occurred in 56.3% of PPC; with M2, they occurred in 64.5% of PPC; and with M3, they occurred in 70.9% of PPC. We concluded that the developed system of regression models is an appropriate method for milk yield prediction of PPC.

Feeding strategies on certified organic dairy farms in Wisconsin and their effect on milk production and income over feed costs

The purposes of this study were (1) to analyze and categorize certified organic Wisconsin dairy farms based on general farm characteristics and feeding strategies during the course of 2010, and (2) to evaluate herd milk production and income over feed costs (IOFC). An on-site survey containing sections on farm demographics, feeding, grazing, and economics was conducted on 69 farms (12.6% survey response rate). A nonhierarchical clustering method using 9 variables related to general farm characteristics, feed supplementation, and grazing was applied to partition the farms into clusters. A scree plot was used to determine the most appropriate number of clusters. Dry matter intake was approximated based on farmer-reported total amounts of feed consumed (feed offered less refusals). Milk production was evaluated using reported milk rolling herd averages (RHA). Income over feed costs was calculated as milk sales minus feed expenses. The farms in clusters 1 (n=8) and 3 (n=32), the large and small high-input farms, respectively, included more feed ingredients in their lactating cow diets and relied more heavily on concentrates than farms in other clusters. Cows on these farms were predominantly Holstein. Clusters 1 and 3 had the highest RHA (6,878 and 7,457kg/cow per year, respectively) and IOFC ($10.17 and $8.59/lactating cow per day, respectively). The farms in cluster 2 (n=5) were completely seasonal, extremely low-input farms that relied much more heavily on pasture as a source of feed, with 4 out of the 5 farms having all of their operated land in pasture. Farms in cluster 2 relied on fewer feeds during both the grazing and nongrazing seasons compared with farms in the other clusters. These farms had the lowest RHA and IOFC at 3,632kg/cow per year and $5.76/lactating cow per day, respectively. Cluster 4 (n=24), the partly seasonal, moderate-input, pasture-based cluster, ranked third for RHA and IOFC (5,417kg/cow per year and $5.92/lactating cow per day, respectively). Breeds other than Holstein were used more prevalently on farms in clusters 2 and 4. Results indicated extreme variation in animal breed, structure, and feeding strategies among Wisconsin organic dairy farms. Feeding strategies appeared to be major determinants of RHA and IOFC. These findings may serve current organic and transition farmers when considering feeding management changes needed to meet organic pasture rule requirements or dealing with dietary supplementation challenges.

Relationships between age at first calving; herd management criteria; and lifetime milk, fat, and protein production in Holstein cattle

ABSTRACT Data from 69,145 Holstein cows that calved in 2005 were evaluated to determine the influence of age at first calving (AFC) on first lactation and lifetime production in commercial dairy herds. A DHI database was divided into 4 herd management criteria (HMC). The 4 HMC were 1) 3X milking and rolling herd average (RHA) = 12,750 kg (3X-H), 2) 3X milking and RHA = 11,250 kg (3X-M), 3) 2X milking and RHA = 11,250 kg (2X-M), and 4) 2X milking and RHA = 9,250 kg (2X-L). For all HMC, a universal loss in first-lactation milk, fat, and protein yield was observed when AFC was

A constant goal, changing tactics: The Krusenbaum dairy farm (1996–2005)

AbstractThis case study documents the trajectory of a successful alternative dairy farm in southeastern Wisconsin. The 1990s were a difficult period for dairying and the Krusenbaum family entered this shifting field in 1990 with a 37-cow Holstein herd in a stanchion barn, 88 tillable hectares and a vision to gradually develop a biodynamic dairy. Low milk prices and the unrelenting workload associated with conventional dairying forced the family to look for alternative strategies. By 1995 they had converted all their land to 47 rotationally grazed paddocks, increased herd size to 70 cows and their annual net farm income had grown to a solid $54,000. The workload remained very heavy, and during the next few years they introduced a swing-16 milking parlor that approximately doubled their milking efficiency and allowed them to again increase herd size, implemented seasonal dairying and constructed an outwintering shed (1997) that greatly facilitated animal management during the winter. By 2002 the farming system had been, by and large, consolidated and by not focusing solely on milk production and crossbreeding with non-Holstein breeds, the herd benefited from improved reproductive vigor. They were then able to synchronize annual calving and the herd's maximum nutritional needs with the spring flush of their pastures, which resulted in lowered purchased feed costs per cow. By this time, annual milk production was fairly constant [around 7400 kg rolling herd average (RHA)], herd health was good and annual net farm income had grown to $75,600. In 2003, the farm became certified organic. With this change the value of the milk increased dramatically from $0.31 liter−1 to $0.45 liter−1 ($14.27–$20.24 per hundredweight), but feed costs climbed sharply due to the high cost of organic feed, as did labor costs due to the decision to train new farmers in grass-based dairying rather than simply hire employees. Due to very sound farm management, good money management and an entrepreneurial philosophy, this farm, by most performance standards, is now both highly profitable and environmentally sound and the families living on it have a good quality of life.

Comparison of Analytical Methods and the Influence of Milk Components on Milk Urea Nitrogen Recovery

The objectives of this study were to compare analytical instruments used in independent laboratories to measure milk urea nitrogen (MUN) and determine whether any components in milk affect the recovery of MUN. Milk samples were collected from 100 Holstein cows fed one ration in a commercial dairy herd with a rolling herd average of 9500kg. Half of each sample was spiked with 4mg/dL of urea N, while the other half was not, to determine recovery. Both milk samples (spiked and not spiked) were sent to 14 independent laboratories involved in the MUN Quality Control Program through National Dairy Herd Improvement Association and analyzed for MUN, fat, protein, lactose, somatic cell count (SCC), and total solids. The laboratories analyzed MUN using CL-10 (n = 3), Skalar (n = 2), Bentley (n = 3), Foss 4000 (n = 3) or Foss 6000 (n = 3) systems. When recovery of MUN was evaluated among the 5 analytical methods, the mean recoveries for the Bentley, Foss 6000, and Skalar systems were 92.1 (SE = 2.76%), 95.4 (SE = 10.1%), and 95.1% (SE = 7.61%), respectively, and did not differ from each other. However, MUN recovery was 85.0% (SE = 2.8%) for the CL-10 system and 47.1% (SE = 9.9%) for the Foss 4000 system, both of which differed from the other 3 systems. Recoveries from Foss 4000, Foss 6000, and Skalar varied among laboratories using the same instrument. As initial MUN concentration increased, recovery decreased using the Bentley and CL-10 systems. Increasing milk fat resulted in a decrease in recovery using the Foss 6000 system. For 4 of the 5 methods, recovery of MUN was not associated with specific milk components. Recovery of MUN was inconsistent for laboratories using the Foss 4000 and the Foss 6000 method and using these systems may result in an overestimation or underestimation of MUN.

Regional Production Differences

The DHI records from 37 states were grouped into North, Midsouth, and South regions and six herd sizes (20 to 49, 50 to 99, 100 to 149, 150 to 249, 250 to 449, and >450 cows). Data were analyzed by region and by herd size for the year 1998. The North region had higher income over feed cost, milk, fat, and protein rolling herd averages than other regions. These variables declined for the Midsouth and were lowest for the South. Days open and somatic cell score (SCS) were lowest in the North and highest in the South. Large herds had higher total feed cost, income over feed cost, milk, fat, and protein rolling herd averages than smaller herds. For the period 1990 to 1999, the data were analyzed for the trend in change over time for each of the regions. Milk production per cow, total feed cost, income over feed cost, days open, and herd sizes increased in the period from 1990 to 1999. Somatic cell score decreased. Different rates of increments over the last decade have made differences among regions larger for milk production, total feed cost, income over feed cost, herd size, and SCS. There were no differences in the rate of change for days open. Milk production per cow and total feed cost increased at higher rates in larger herds, making the gap between these and smaller herds larger over time. Income over feed cost, days open, and herd size changes had similar rates of change during the decade, keeping differences among herd sizes constant over time. The SCS decreased at a higher rate in the smallest herds than in larger herds, making the gap between them smaller.

Sources of Variation in Milk Urea Nitrogen in Ohio Dairy Herds

The purpose of this study was to estimate the amount of variation in milk urea nitrogen (MUN) concentrations attributable to test-day, individual cow, and herd effects and to describe factors associated with MUN measurements in Ohio dairy herds. The data came from 24 Holstein herds, half of which were classified as low producing (LP) [rolling herd average (RHA) milk production<7,258 kg] and half as high producing (HP) herds (RHA production>10,433kg). MUN concentration was measured from cow's monthly test-day milk samples. The data were analyzed using multilevel modeling technique in MLwiN, separately for LP and HP herds.The unadjusted mean MUN was 13.9 mg/dl for the HP herds and 11.3 mg/dl for the LP herds. The variance structure was different between the two groups. Most of the variability was found at test-day level in the LP herds, but at herd level in HP herds. MUN was lowest during the first month of lactation, and also season was associated with MUN in both groups. Test-day milk yield, milk fat percentage, and SCC were associated with MUN in the HP herds. With significant explanatory variables in the model, proportionally more of the variation was explained at herd level and less at test day level in both groups.Lower variability in MUN between test days in the HP herds may indicate more consistent day-to-day feeding and management within a herd. The great variability between test days should be considered when interpreting MUN and samples should be collected at the same time of the day to minimize day-to-day variability.

Non-Dietary Sources of Variation in Milk Urea Nitrogen in Ohio Dairy Herds

Protein is an expensive component of dairy cow diet and excessive protein feeding has been associated with decreased fertility. Urea is the end product of protein metabolism in dairy cattle. Milk urea nitrogen (MUN) can be used to monitor the protein feeding efficiency and protein-energy ratio in dairy cow rations. The purpose of this study was to describe the non-dietary sources of variation in and the factors associated with MUN levels in Ohio dairy herds. The data came from 24 herds belonging to Ohio Dairy Herd Improvement Association. Half of the herds (12) were classified as low producing herds (rolling herd average (RHA) milk production 10,433 kg). MUN concentration was measured spectrophotometrically from monthly test day milk samples by an automated procedure with a Skalar Segmented Flow Analyzer. We had observations from 12,939 test days, from 1681 cows. The data were analyzed using multilevel modelling technique in MLwiN ® , separately for both production groups. Different levels of organization were herd, cow, and test day. Initially, a simple random intercept model containing only a constant was run. Explanatory variables previously identified being associated with MUN were added to the model as fixed effects and model was reduced until all variables were significant at ?=0.05 level. The average MUN level from the simple intercept-only model was 14.1 mg/dl and 11.0 mg/dl in the high and low producing herds, respectively. The overall variation in MUN's was greater in low producing herds than in high producing herds. Also, the variance structure was quite different between these two groups. In low producing herds, 67.2% of the variation in MUN's was at the test day level, only 0.5% at cow level and 32.3% at herd level. In the high producing herds, however, highest proportion of variance (49.0%) was found at the herd level and 38.9% of the variation was at the test day level. Between-cow variability accounted for 12.1% of the variance in MUN's. With the independent variables in the model, variation was reduced in low production group (by 16%), but practically no change in magnitude took place in the high production group. The results also indicated that measurements taken during the first month of lactation were significantly lower than ones taken later in the lactation. Also, the season of the test day was associated with MUN levels (summer or spring with highest levels). Cow's test day milk yield and fat-protein ratio in milk in high producing herds were also positively associated with MUN levels. In low producing herds, milk fat percentage was negatively associated with MUN levels. The observed differences in the proportions of variance at the different levels between the production groups may be explained by management factors. Lower variability in MUN between test days in high producing herds probably indicates more consistent day-to-day feeding and management within a herd in this group.

Effect of Region and Herd Size on Dairy Herd Performance Parameters

Differences in selected Dairy Herd Improvement (DHI) performance parameters among regions and herds of different size categories were evaluated. DHI records from herds in 37 states were grouped into North, Midsouth, and South regions, and six herd size categories (20 to 49, 50 to 99, 100 to 149, 150 to 249, 250 to 449, and ≥450 cows). The North region had higher income over feed costs (IOFC); milk, fat, and protein rolling herd averages; summit milk; standardized 150-d milk; and percentage of cows in milk, than the other regions. These variables were lowest for the South region. Cost/45.4kg of milk, days open, days dry, and somatic cell counts were lowest in the North region and were highest in the South. Percentage of cows entering and leaving the herd were highest in the Midsouth and were lowest in the South. Larger herds had higher total feed cost, IOFC, milk, fat, and protein rolling herd averages, summit milk, standardized 150-d milk, percentage of cows entering and percentage leaving the herd than smaller herds. Larger herds had lower somatic cell counts than smaller herds. Cost/45.4kg of milk, days dry, days open, days in milk, and percentage of cows in milk did not show clear trends among different herd sizes. There were significant interactions between region and herd size for some of the variables.

Reproductive Performance of Holstein Cows Receiving Somatotropin

Some dairy producers resist using bovine somatotropin (bST) beginning at 9 wk postpartum because of the concern that fertility is compromised. We conducted a trial with a total of 205 Holstein cows, 100 multiparous and 105 primiparous, to evaluate reproductive performance in two high producing herds in Arizona and southern California. Rolling herd averages for both herds for milk production exceeded 10,700 kg/yr. Data were collected for cows calving December 1996 through August 1997. The voluntary waiting period was 60 d postcalving, with cows randomly assigned to receive bST or no treatment (controls). In the 180-d interval after calving, 65.4% (68/104) of the control cows were diagnosed pregnant. With bST-treated cows, 48.5% (49/101) were pregnant in that same interval. A chi-square value from a linear model indicated that pregnancy outcome differed significantly between treatment groups. With a similar method of analysis, first-service conception rate was not significantly different between treatment groups. An extended voluntary wait and breeding interval is recommended for cows receiving bST, similar to suggestions from other published reports.

Corrigendum to “A linear programming assessment of the profit from strategies to reduce the prevalence of Staphylococcusaureus mastitis” [Prev. Vet. Med. 33 (1998) 183–193

We used a linear programming model to estimate the financial returns to a Staphylococcus aureus testing and control program over a 1-year period for a 100-cow herd, with a 8636 kg rolling-herd average. Six tests, which vary in sensitivity from 0.80 to 0.98 and specificity of 0.99, were examined in simulated herds with 10, 20, and 30% prevalence of S. aureus infection. Sensitivity of these results to a range of assumptions regarding rolling-herd average, milk price, somatic cell-count premium, and cost and cure rate of dry treatment were examined to determine the profits from the program. The profits of a control program are most dependent upon prevalence and cell-count premium. In our simulation for a 100-cow herd, a testing and control program results in a profit ranging from US$1.50 to US$20 per cow per year, except under the lowest prevalence and most-adverse conditions (low yield or low SCC premium).

Effect of Time of Artificial Insemination on Pregnancy Rates, Calving Rates, Pregnancy Loss, and Gender Ratio After Synchronization of Ovulation in Lactating Dairy Cows

In order to assess the optimal time of artificial insemination (AI) in relation to ovulation, lactating dairy cows (n = 732) from herds with rolling herd averages of 9980 to 11,800kg from three milkings per day were randomly assigned to five groups by stage of lactation and parity. Ovulation was synchronized by administration of GnRH followed 7 d later with PGF2α followed 2 d later with a second treatment with GnRH. Cows were inseminated at 0, 8, 16, 24, or 32h after the second injection of GnRH (ovulation occurs between 24 and 32h after GnRH). Pregnancy diagnoses were performed by ultrasound at 25 to 35 d post-AI. Pregnancy rates per AI were similar for the groups inseminated at 0, 8, 16, and 24h and lower for the group inseminated at 32h. A significant quadratic effect of treatment suggests that the middle time periods (8, 16, and 24h) may produce the greatest pregnancy rate per AI. However, the group inseminated at 0h had lowest pregnancy loss, and the group inseminated at 32h tended to have the greatest pregnancy loss compared with that of the other groups. The calving rate was similar between the groups inseminated at 0, 8, 16, and 24h and lower in the group inseminated at 32h. The time of AI also appeared to affect gender of calf: cows bred at 0 and 32h having a higher percentage of female offspring. In conclusion, there appears to be substantial flexibility in the time of AI after the second injection of GnRH, and lower reproductive rates were observed only when AI was after the time of ovulation.

Constant Goal, Changing Tactics: A Wisconsin Dairy Farm Start-up

AbstractThis case study documents the start-up of a successful alternative dairy farm in Wisconsin. Initially the vision was to establish a 97-ha biodynamic farm with dairy and cash cropping. Low milk prices throughout most of 1991 and the heavy work load associated with conventional dairying forced the farm family to look for alternative strategies. They experimented with management-intensive grazing in 1992, and by spring 1994 had seeded their entire farm to sod. The work load still was too heavy, so they switched to seasonal dairying and outwintering of their dry stock, which reduced the daily midwinter work load from 12 to 3.5 hours. By the end of 1995, yearly net farm income from operations had risen from $21,500 (1990 and 1991) to $54,000 (1994 and 1995). The farm family, with its alternative approach (biodynamic, grass-based, seasonal milking) weathered the stresses of entering dairy farming at a time when entry rates were very low and existing dairy farmers faced substantial financial pressure. The grassbased system required low purchased feed inputs ($300 per cow) and nearly reached equilibrium in the whole-farm nutrient budget. Good herd management has maintained high productivity (rolling herd average of 17,000 lbs) and excellent herd health. Renting the farm and managing money carefully have resulted in a low debt load ($73 per cow). This study illustrates the complexities and adjustments associated with the initiation of an alternative farm business.

Effect of Dietary Yeast Culture on Milk Yield, Composition, and Component Yields at Commercial Dairies

A field trial was conducted to evaluate the effect of dietary yeast culture on milk yield, composition, and component yields at 11 commercial dairies in Wisconsin. Rolling herd averages ranged from 10,000 to 12,800kg per cow. Yeast culture was added to total mixed rations to allow an average daily intake of 57g over two 30-d Dairy Herd Improvement (DHI) test periods. Production data from the 30-d DHI test periods immediately before and after the yeast culture feeding period were used as the control. There were 585 cows (245 primiparous and 340 multiparous) that completed the four 30-d period feeding sequence (OFF-ON-ON-OFF). Average days in milk were similar for the yeast and control feeding periods (140.0 vs 140.5, respectively). Dietary yeast culture increased (P<0.001) actual and 150 d adjusted milk yields 0.90kg/d. Milk fat content was lower (P<0.001) for cows fed yeast culture (3.55 vs 3.65%), but milk fat yield was similar. Dietary yeast culture reduced (P<0.05) milk protein content 0.02 percentage units, but protein yield was higher (P<0.01) for cows fed yeast culture (1.17 vs 1.14 kg/d). The milk yield response was positive in 8 of 11 herds (herd by treatment interaction; P<0.001). These data indicate that under the conditions of this study the addition of yeast culture to total mixed rations for mid lactation dairy cows in high producing commercial herds increases milk and protein yield.

Practical approach to the diagnosis of a dairy herd problem

A 390 cow dairy presented in August of 1994 with a complaint of chronic respiratory disease in their milking herd. The history involved numerous management changes over the previous 2 years, including 3 changes in nutritionists, purchase of 37 new heifers from 2 outside sources and construction of a new milking parlor. An investigation of the herd established that the rolling herd average had declined nearly 6000 lb in the previous year and a half. The dairy had a cumulative incidence of cystic ovaries in a 3 month cohort of cows of 46% and body condition scores were well below desirable goals for the whole herd. The major problems of decreased milk production and loss of body condition were the focus of the investigation. Although the total mixed ration formulation calculated and recommended by the current nutritionist was deemed to be adequately balanced for each milking string, analysis of the cow rations revealed an energy deficit of 6.03 Mcal/cow/day for the top milking string and comparable deficits for the lower strings. It was discovered that the auger used to meter out grain for the total mixed ration was miscalibrated. The auger was delivering 22% less grain into the ration than was believed. The producer had the auger calibrated to correct the problem. A follow up investigation was done nearly 2 years later, in May of 1996, to evaluate the changes in milk production, services per conception, body condition scores and other parameters over a 6 year period. Both rolling herd average and body conditions had improved markedly from the time of the original investigation. This case was used as a general example of how to approach the diagnosis of a herd problem.

Management practices associated with high mortality among preweaned dairy heifers

In a national survey of US dairy operations, 1685 dairy operations reported 47,057 new dairy heifers (either births or acquisitions) and 4427 deaths (9.4%) of preweaned dairy heifer calves over a 3 month period. Stepwise logistic regression was used to identify management practices associated with high mortality among preweaned heifers in dairy operations where at least three dairy heifer calves were born alive or moved on to the operation. Analysis was done twice: once by separating all operations by size into high or low mortality; again using only operations with < 2 and > 10% mortality to eliminate dairy operations with intermediate levels of mortality from the comparisons. Results were similar. Dairy operations in the West were more likely to fall in the high mortality category than dairy operations in the rest of the country. In addition, the following dairy operation characteristics were associated with high death levels in both models: rolling herd average milk production < 7710 kg. preweaned heifers placed in groups of seven or more, a male having primary responsibility for the care and feeding of preweaned heifers, calves not receiving hay or other roughages until > 20 d old, calves fed on mastitic or antibiotic milk after colostrum and calves not given whole milk after colostrum.