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Biomedical subjects

W G Merrill

Publications and source records attributed to W G Merrill.

9 recordsLinked to original sources
PubMed1995

A decision support system for evaluating mastitis information.

A data-driven decision support system, MAST, was developed to summarize systematically the DHI data related to mastitis. MAST determines weaknesses and problems of a mastitis control strategy by pinpointing problem areas, highlighting the scope of the mastitis problem, providing reference values for comparison, offering potential solutions to problem areas, and monitoring changes in the control strategy. Advantages of a DHI data-driven system include accuracy of input data, fast execution speeds, access to untapped information available in DHI data, and a consistent analysis of data. An on-farm decision support system allows the evaluation of the mastitis control strategy at any time, which in turn increases the value of DHI information. The sequence of the graphical results allows users to understand intuitively the overall mastitis problems, find the potential origins, and assess their impact on the herd. Color-coded graphs with supplementary text allow for a rapid analysis of level and trends over time, as well as comparisons among parities, lactation stages, and active and culled cows.

Animals↗
PubMed1988

Evaluation of udder preparations on intramammary infections.

Udder preparations of wet towel plus drying and .1% iodophor premilking teat dipping plus drying were compared with no preparation to determine effects on number of new intramammary infections. Teats of 84 cows were challenged (5 d/wk) for 18 wk with a culture broth of Streptococcus uberis 3 h prior to each p.m. milking to stimulate environmental contamination. Wet towel plus drying and premilking teat dipping plus drying significantly reduced number of new intramammary infections compared to no preparation. Cleaning with water or dipping with a premilking teat dip and manual drying of teats may have contributed to the reduction in number of new infections. Premilking teat dipping plus drying further reduced number of new infections compared to use of wet towel plus drying. Apparently, teat dipping was more effective in reducing the number of new infections than water used with the wet towel. This study showed that udder preparations can affect udder health when an experimental bacterial challenge is applied.

Animals↗
PubMed1987

Effects of premilking stimulation on complete lactation milk yield and milking performance.

Effects of premilking preparation on complete lactation performance were measured with two groups of multiparous Holstein cows; 1) 17 cows received full stimulation, a 60-s routine, and 2) 16 cows received minimum stimulation, a 15-s routine, before machine attachment. Actual unadjusted average lactation milk yield for cows receiving full stimulation was 5.4% less than that for cows receiving minimum stimulation. When postpeak persistencies were compared by linear regression of either 1) daily milk weights or 2) 3.5% FCM from DHI records of milk yield and milk fat percent and fitted to lactation curves using an incomplete gamma function, cows receiving full stimulation produced 1) 2.8 or 2) 2.5% more milk per lactation than did cows receiving minimal stimulation. However, none of the treatment differences in mean milk yield was significant statistically. Milk flow rates, strip yields, and machine on-times were measured at 8-wk intervals throughout lactation. Cows receiving full stimulation had significantly higher average milk flow rates and shorter machine on-times starting at wk 32. There were no significant differences in strip yields or percent residual milk between cows receiving full and minimum stimulation.

Animals↗
PubMed1984

Effects of premilking udder preparation on bacterial population, sediment, and iodine residue in milk.

Udder preparations that wet both udder surfaces and teats had the highest standard plate count in milk compared with methods that wet teats only. Physical action of cleaning teats with a dry towel lowered bacterial count compared with preparations wetting both udder surfaces and teats. Methods resulting in lowest bacterial counts were the use of water hose, wet towel, or premilking disinfectant teat dip followed by drying with paper towels. Counts of coliform and Staphylococcus sp. followed similar trends. In most comparisons, addition of udder wash sanitizer was of marginal or no benefit. Standard plate count of teat rinses after udder preparation confirmed the benefit of cleaning and drying teats. Physical manipulation of teats during cleaning was essential for lowering sediment in milk. Drying of teats with a paper towel for at least 10 s after dipping with a 1% iodophor disinfectant dip was essential for reducing iodine residue. Both premilking and postmilking disinfectant teat dipping with a 1% iodophor teat dip caused higher iodine residue in milk than premilking disinfectant dip with subsequent drying. A .5% iodophor teat dip contributed less iodine in milk than a 1% iodophor teat dip. Premilking udder preparation affects bacterial count, sediment, and iodine residue in milk.

Animals↗
PubMed1983

Current concepts on the role of oxytocin in milk ejection.

Timing of oxytocin release may influence milk ejection. Oxytocin is higher in cows after manual premilking stimulation than in cows receiving no stimulation. Premilking stimulation offers no advantages to milk production in short trials but results in shorter times of machine on and higher average rate of milk flow. Enhanced mechanical stimulation does not seem as effective as manual stimulation in short trials. Oxytocin release is multiphasic, and contents in blood decline during milking. Maximal concentrations during milking decrease across lactation. Nonlactating cows also release oxytocin upon udder stimulation and conditioning. Virgin heifers do not respond in the same way to udder stimulation as lactating cows, thus suggesting that sensitivity of the milk ejection reflex depends upon the physiological state of the animal. Cows probably release about one-third of their stores of oxytocin at milking, and it appears that little hormone is necessary for effect at the udder. Basal concentrations of oxytocin decrease from early to midlactation and increase from mid to late lactation and from late lactation to involution. Half-lives, metabolic clearance rates, and entry rates for oxytocin were measured in cattle in various physiological states. Data from these measurements are discussed.

Animals↗
PubMed1980

Premilking stimulation effects on milking performance and oxytocin and prolactin release in cows.

For effects on milking performance, 12 Holstein cows were subjected to four stimulation routines: a) no stimulation, b) manual stimulation, c) manual stimulation with delayed milking, and d) intravenous infusion of .75 IU of oxytocin. In an added experiment, effects of the first two treatments on milking performance and release of oxytocin and prolactin were measured. Milk yield, fat, and protein content were not affected by any treatment. Machine-on times were shorter and peak and average milk flow rates higher for manually stimulated and oxytocin and prolactin in sera at resting were 5.25 microU/ml and 16.5 ng/ml. Differences between mean peak concentrations of oxytocin (16.6 and 16.0 microU/ml) and prolactin (28.1 and 27.5 ng/ml) for stimulated and unstimulated cows were small. Mean oxytocin concentration in stimulated cows peaked at 2 min compared with 5 min for unstimulated cows. No difference in time of prolactin release was detected. The timing of oxytocin release, rather than maximal concentration, could be the most important factor affecting milking.

Animals↗