Douglas J. Reinemann

Interactions of vacuum, b-phase duration, and liner compression on milk flow rates in dairy cows

Vacuum, b-phase duration, and liner compression are 3 milking machine factors that affect peak milk flow rate; however, extreme values of these factors can also have negative effects on teat tissue health. The main and interactive effects of vacuum, b-phase duration, and liner compression on peak milk flow rate were studied by independently controlling these causal variables over a wide range of settings, using a central composite experimental design (42 to 53 kPa of system vacuum, 220 to 800 ms of b-phase, and residual vacuum for massage of 16 to 30 kPa; corresponding to a liner compression of 8 to 14 kPa). The results of this study indicated that increasing the vacuum and b-phase duration always increased peak milk flow rate (no relative maximum was reached); however, the rate of increase of flow rate decreased as the vacuum and b-phase were increased. Increasing the liner compression also increased peak flow rates, with an increasing effect at greater vacuum. The interaction between vacuum and liner compression and the lack of interaction between b-phase and liner compression indicate that for a corresponding increase in peak milk flow rate, increasing the b-phase produced less teat-end tissue congestion than increasing the vacuum. The effect of milking vacuum on peak milk flow rate was smaller than that reported in previous studies, probably because of the independent adjustment of milking vacuum and liner compression used in this study. The effect of b-phase duration on peak milk flow was also smaller in this study than in previous studies, probably because of the independent adjustment of b-phase and d-phase durations used in this study.

Factors associated with coliform count in unpasteurized bulk milk

The objective of this study was to identify factors associated with bulk milk coliform count (CC). Dairy farms (n=10) were visited once weekly on sequential weekdays over a period of 10 wk. During each visit, in-line drip samplers were used to collect 1 milk sample from 2 points of the milk line (between the receiver jar and milk filters, and after the plate cooler). During the same period that in-line milk samples were collected, university personnel observed milking performance and hygiene and collected liner (n=40) and teat skin swabs (n=40). Coliform counts were determined for milk samples and swabs using Petrifilm CC plates (3M, St. Paul, MN). A mixed model was used to assess the association between in-line milk CC (ILCC) and several potential predictor variables. The mean duration of each visit was 73 min and the time between start of milking and beginning of milk sampling was 154 min. The mean number of cows milked during each visit was 236. For all milk samples (n=181), geometric mean ILCC was 37 cfu/mL. In-line milk CC varied by farm, ranging from 5 to 1,198 cfu/mL. Rate of fall-offs, rate of cluster washes, outdoor and indoor temperature, indoor humidity, sampling duration, and parity group were unconditionally associated with ILCC but did not enter the final multivariate model. In-line milk CC was 4 times greater (115 cfu/mL) when milking machine wash failures occurred compared with ILCC after normal washes (26 cfu/mL). Pre-filter and post-cooler ILCC were not different when milk samples were collected at the beginning (<33% of herd milked) or at mid-milking (33 to 66% of the herd milked), whereas pre-filter ILCC was less than post-cooler for samples collected at the end of milking (>67% of the herd milked). Geometric mean ILCC (cfu/mL) increased 6.3% for every 10% increase in in-line milk SCC (cells/mL). Geometric mean ILCC increased 2.3% for every 10% increase in liner CC (cfu/mL). Results of this study provide novel information about farm factors associated with CC, as estimated in milk before storage in tankers or bulk tanks, and highlight the importance of proper and consistent milking machine washes in minimizing bulk milk coliform contamination. The nature of the associations between liner CC, rate of cluster washes, rate of milking units fall-offs, and ILCC indicates that managing and monitoring such events has the potential for improving bacteriological quality of farm bulk milk.

Life Cycle Impact Assessment and Allocation Methods Development for Cheese and Whey Processing

In this study, life cycle assessment (LCA) methods are used to develop life cycle inventory (LCI) and life cycle impact assessment (LCIA) data to estimate the global warming potential (GWP) and energy intensity (EI) of cheese and dry whey manufacturing in Wisconsin using a farm gate to plant gate approach. All of the environmental burdens and benefits are assigned to the product (cheese) and none are assigned to the land-spread waste stream (whey) for a single-output system typical of small cheese plants in Wisconsin. For a multifunction system, in which both cheese and food-grade whey are produced, the following methods are applied to handle co-product multifunctionality: subdivision, allocation ratios, and a method that combines both subdivision and allocation ratios. Total solids, nutritional content, and economic value are considered as the allocation ratios. Each of these fixed allocation ratios is applied to the entire process and to individual processes unique to each product. The differences in the GWP and EI for cheese and dry whey are highly influenced by the choice of method. The EI of cheese ranges from 7.1 to 19 MJ kg-1 cheese, and the GWP of cheese ranges from 0.46 to 1.3 kg CO2-eq kg-1 cheese. The main source of these differences is the shift of environmental burdens from cheese to the dry whey co-product resulting from different allocation strategies. The method that combines subdivision and allocation is presented as the preferred and most accurate method to deal with the multifunctionality of cheese and whey manufacturing. Sensitivity analysis shows that GWP and EI are most affected by variations in milk pasteurization, whey evaporation, whey drying, and whey pasteurization. This study demonstrates the importance of the allocation method on LCA analysis and suggests methods to more accurately assess the environmental burdens when more than one product is produced at a dairy plant.

Effect of pulsation rest phase duration on teat end congestion

The objective of this study was to quantify the effect of d-phase (rest phase) duration of pulsation on the teat canal cross-sectional area during the period of peak milk flow from bovine teats. A secondary objective was to test if the effect of d-phase duration on teat canal cross-sectional area was influenced by milking system vacuum level, milking phase (b-phase) duration, and liner overpressure. During the d-phase of the pulsation cycle, liner compression facilitates venous flow and removal of fluids accumulated in teat-end tissues. It was hypothesized that a short-duration d-phase would result in congestion of teat-end tissue and a corresponding reduction in the cross-sectional area of the teat canal. A quarter milking device, designed and built at the Milking Research and Instruction Laboratory at the University of Wisconsin-Madison, was used to implement an experiment to test this hypothesis. Pulsator rate and ratios were adjusted to achieve 7 levels of d-phase duration: 50, 100, 150, 175, 200, 250, and 300ms. These 7 d-phase durations were applied during one milking session and were repeated for 2 vacuum levels (40 and 50kPa), 2 milking phase durations (575 and 775ms), and 2 levels of liner overpressure (9.8 and 18kPa). We observed a significant reduction in the estimated cross-sectional area of the teat canal with d-phase durations of 50 and 100ms when compared with d-phase durations of 150, 175, 225, 250, and 300ms. No significant difference was found in the estimated cross-sectional area of the teat canal for d-phase durations from 150 to 300ms. No significant interaction was observed between the effect of d-phase and b-phase durations, vacuum level, or liner overpressure.

Methods of estimating liner compression

The aim of this study was to compare 2 methods of measuring overpressure (OP) using a new test device designed to make OP measurements more quickly and accurately. Overpressure was measured with no pulsation (OP np) and with limited pulsation (OP lp) repeatedly on the same cow during a single milking. Each of the 6 liners (3 round liners and 3 triangular liners) used in this study were tested on the same 6 experimental cows. Both OP np and OP lp were measured on all 4 teats of each experimental cow twice for each liner. The order of OP np and OP lp alternated sequentially for each cow test. The OP results for the 6 liners were also compared with liner compression estimated on the same liners with a novel artificial teat sensor (ATS). The OP lp method showed small but significantly higher values than the OP np method (13.9 vs. 13.4 kPa). The OP lp method is recommended as the preferred method as it more closely approximates normal milking condition. Overpressure values decreased significantly between the first and the following measurements, (from 15.0 to 12.4 kPa). We recommend performing the OP test at a consistent time, 1 min after attaching the teatcup to a well-stimulated teat, to reduce the variability produced by OP changing during the peak flow period. The new test device had several advantages over previously published methods of measuring OP. A high correlation between OP and liner compression estimated by the ATS was found, but difficulties were noted when using the ATS with triangular liners.

Potential for Electrified Vehicles to Contribute to U.S. Petroleum and Climate Goals and Implications for Advanced Biofuels

To examine the national fuel and emissions impacts from increasingly electrified light-duty transportation, we reconstructed the vehicle technology portfolios from two national vehicle studies. Using these vehicle portfolios, we normalized assumptions and examined sensitivity around the rates of electrified vehicle penetration, travel demand growth, and electricity decarbonization. We further examined the impact of substituting low-carbon advanced cellulosic biofuels in place of petroleum. Twenty-seven scenarios were benchmarked against a 50% petroleum-reduction target and an 80% GHG-reduction target. We found that with high rates of electrification (40% of miles traveled) the petroleum-reduction benchmark could be satisfied, even with high travel demand growth. The same highly electrified scenarios, however, could not satisfy 80% GHG-reduction targets, even assuming 80% decarbonized electricity and no growth in travel demand. Regardless of precise consumer vehicle preferences, emissions are a function of the total reliance on electricity versus liquid fuels and the corresponding greenhouse gas intensities of both. We found that at a relatively high rate of electrification (40% of miles and 26% by fuel), an 80% GHG reduction could only be achieved with significant quantities of low-carbon liquid fuel in cases with low or moderate travel demand growth.

Life cycle assessment of switchgrass cellulosic ethanol production in the Wisconsin and Michigan agricultural contexts.

Spatial variability in yields and greenhouse gas emissions from soils has been identified as a key source of variability in life cycle assessments (LCAs) of agricultural products such as cellulosic ethanol. This study aims to conduct an LCA of cellulosic ethanol production from switchgrass in a way that captures this spatial variability and tests results for sensitivity to using spatially averaged results. The Environment Policy Integrated Climate (EPIC) model was used to calculate switchgrass yields, greenhouse gas (GHG) emissions, and nitrogen and phosphorus emissions from crop production in southern Wisconsin and Michigan at the watershed scale. These data were combined with cellulosic ethanol production data via ammonia fiber expansion and dilute acid pretreatment methods and region-specific electricity production data into an LCA model of eight ethanol production scenarios. Standard deviations from the spatial mean yields and soil emissions were used to test the sensitivity of net energy ratio, global warming potential intensity, and eutrophication and acidification potential metrics to spatial variability. Substantial variation in the eutrophication potential was also observed when nitrogen and phosphorus emissions from soils were varied. This work illustrates the need for spatially explicit agricultural production data in the LCA of biofuels and other agricultural products.

Estimating teat canal cross-sectional area to determine the effects of teat-end and mouthpiece chamber vacuum on teat congestion

The primary objective of this experiment was to assess the effect of mouthpiece chamber vacuum on teat-end congestion. The secondary objective was to assess the interactive effects of mouthpiece chamber vacuum with teat-end vacuum and pulsation setting on teat-end congestion. The influence of system vacuum, pulsation settings, mouthpiece chamber vacuum, and teat-end vacuum on teat-end congestion were tested in a 2×2 factorial design. The low-risk conditions for teat-end congestion (TEL) were 40 kPa system vacuum (Vs) and 400-ms pulsation b-phase. The high-risk conditions for teat-end congestion (TEH) were 49 kPa Vs and 700-ms b-phase. The low-risk condition for teat-barrel congestion (TBL) was created by venting the liner mouthpiece chamber to atmosphere. In the high-risk condition for teat-barrel congestion (TBH) the mouthpiece chamber was connected to short milk tube vacuum. Eight cows (32 quarters) were used in the experiment conducted during 0400 h milkings. All cows received all treatments over the entire experimental period. Teatcups were removed after 150 s for all treatments to standardize the exposure period. Calculated teat canal cross-sectional area (CA) was used to assess congestion of teat tissue. The main effect of the teat-end treatment was a reduction in CA of 9.9% between TEL and TEH conditions, for both levels of teat-barrel congestion risk. The main effect of the teat-barrel treatment was remarkably similar, with a decrease of 9.7% in CA between TBL and TBH conditions for both levels of teat-end congestion risk. No interaction between treatments was detected, hence the main effects are additive. The most aggressive of the 4 treatment combinations (TEH plus TBH) had a CA estimate 20% smaller than for the most gentle treatment combination (TEL plus TBL). The conditions designed to impair circulation in the teat barrel also had a deleterious effect on circulation at the teat end. This experiment highlights the importance of elevated mouthpiece chamber vacuum on teat-end congestion and resultant decreases in CA.

Energy Inputs for Corn Production in Wisconsin and Germany

Corn is one of the most important agricultural commodities in U.S. agriculture not least because of the expansion of ethanol production. The main purpose of this analysis is to quantify the total energy input used to produce corn in Wisconsin and to improve the quality of data and the methodology in the estimation. Therefore a comprehensive literature review was done. The calculation of the energy demand includes direct energy (for example fuel, electricity) and indirect energy (for example fertilizer, seed and machines). Data from the United States Department of Agriculture (USDA) are used to assess the development of the cultivation of corn over the last 30 years; especially the yields and the input of fertilizer in corn production are regarded.

Biomechanics of Milking: Teat - Liner Interactions

This purpose of this paper is to clarify the concept of liner compression and to show the practical importance of understanding and controlling its effects. The degree of compression applied to the teat by the teatcup liner in the d-phase of pulsation has a marked influence on teat condition, cow comfort and peak milk flow-rate. The influence of liner compression on these three characteristics is at least as great as the effects of pulsator ratio, pulsation rate, and the rates of change in air pressure in the teatcup pulsation chamber. Liner Compression (LC) is defined here as the mean compressive pressure which is applied to the inner tissues of the teat apex by the liner during the d-phase of pulsation. Over-pressure (OP) is defined as the mean compressive pressure, above that required to stop milk flowing from the teat, which is applied to the inner tissues of the teat apex by the liner during the d-phase. Thus, OP is a major component of LC. Liner OP values within the range 8-12 kPa appear to achieve the main purposes of pulsation and to maintain good teat condition and cow comfort. OP values < 8 kPa may be too low to fully relieve teat wall congestion induced by the milking vacuum during the b-phase of pulsation. Peak milking rate continues to increase up to liner OP values of 14 kPa. However, the proportion of cows with poorer teat-end condition (hyperkeratosis) appears to be greater at OP values of 14 kPa or more.