The effect of manual and mechanical stimulation on oxytocin release and milking characteristics in Holstein cows milked 3 times daily

Prestimulation administered to a cow before attachment of the milking unit has historically been performed manually. Development of innovative milking technology has allowed manual stimulation to be replaced by mechanical forms of stimulation. Holstein cows (n=30) were enrolled in a crossover design to determine the effect of manual stimulation (forestripping and drying) and high-vibration pulsation on oxytocin profiles, milk yield, milk flow rates, incidence of delayed milk ejection causing bimodal milk flow curves, and residual milk in Holstein cows milked 3 times daily (3×). All cows were subjected to all treatments. Cows received manual (forestripping and drying) or mechanical (high-vibration pulsation) stimulation along with lag times of 0, 30, or 90 s for 21 consecutive milkings. Forestripping involved the manual removal of 2 streams of milk from each teat and drying of the teats. High-vibration pulsation involved increasing the pulsation cycles from 60 to 300 pulses/min and reducing the vacuum in the pulsation chamber to 20 kPa. The 5 treatments were (1) immediate attachment of the milking machine under normal pulsation (T0); (2) dip plus forestrip and drying with 30-s lag time (FD30); (3) dip plus forestrip and drying with 90-s lag time (FD90); (4) high-vibration pulsation for 30 s (HV30); and (5) high-vibration pulsation for 90 s (HV90). Milk yield per milking averaged 14.0 kg and was significantly different among treatments; however, the maximum difference detected among treatments was 0.8 kg/milking. Milking unit on-time, which represents the time when the milking unit is under normal pulsation and harvesting milk (excluding the high-vibration pulsation time of 30 or 90 s), was shortest (245 s) for cows subjected to 90 s of high-vibration pulsation (HV90) and ranged from 256 to 261 s for all other treatments. Milk harvest may have begun during high-vibration pulsation; however, only 0.13 and 0.32 kg of milk was harvested during high-vibration pulsation for HV30 and HV90, respectively. The incidence of bimodal milk curves was lowest for FD90 (7%) and highest for T0 (21%). The somatic cell count was <72×10(3) cells/mL for all treatments. Residual milk obtained by giving 10 IU of oxytocin in the jugular vein followed by 2 min of milking unit attachment represented 12 to 14% of the total milk and did not differ among treatments. Endogenous oxytocin profiles peaked between 12.4 and 18.3 pg/mL for all treatments, and the peak occurred sooner in manually stimulated cows; however, we detected no difference in oxytocin concentration beyond 2 min after milking unit attachment. High-vibration pulsation elicited a similar oxytocin release when taking the start time of stimulation from manual stimulation or high vibration into consideration. Forestripping for visual observation of milk combined with the use of high-vibration stimulation may reduce variation in the milking routine. A predetermined lag time with minimal variation may be achieved via the time spent in high-vibration stimulation instead of a lag period dictated by milking personnel.

Effects of an Automatic Postmilking Teat Dipping System on New Intramammary Infections and Iodine in Milk

A technology of automatically applying a postmilking teat dip via the milking machine prior to machine detachment was compared to manual postmilking teat dipping with a teat dip cup for effects on new IMI and iodine content in milk. One hundred twenty Holstein cows were experimentally challenged in a 22-wk trial with Streptococcus agalactiae and Staphylococcus aureus and 148 Holstein cows were experimentally challenged with Streptococcus uberis in another 22-wk trial. The bacterial suspensions were applied to teats of all of the cows after premilking udder preparation and immediately prior to milking machine attachment. In both trials, cows were divided among four treatments: no postmilking teat dipping; manual postmilking teat dipping with a proven efficacious iodophor teat dip; manual postmilking teat dipping with an iodophor teat dip formulated for an automatic postmilking teat dipping system; and automatically postmilking teat dipping via milking machines with an iodophor teat dip formulated for the automatic postmilking teat dipping system. The postmilking teat dipping treatments reduced new Staph. aureus IMI by 64.5, 76.5, and 88.2%; new Strep. agalactiae IMI by 61.5, 77.8, and 94.4%; and new Strep. uberis IMI by 63.5, 82.5, and 93.8%, respectively, against the treatment of no postmilking teat dipping. The treatment applying the postmilking teat dip automatically via milking machines had the lowest number of new IMI caused by the three pathogens. Teat end and teat skin condition were characterized as normal at the end of the study with no differences between treatments. There were no differences with regard to iodine content in milk between treatments.

Effects of alley and stall surfaces on indices of claw and leg health in dairy cattle housed in a free-stall barn

A 15-wk 2 x 3 factorial trial in a university dairy herd compared the effects of two alley surfaces and three free-stall beds on indices of lameness. Alley surfaces were grooved concrete (Ct) or 1.9-cm-thick interlocking rubber mats (R). Stalls were deep sand (S), rubber mattresses (M), or concrete (C). Mattress and concrete stalls were bedded with sawdust. At wk 1 and 15, the hind claws and hocks of 120 primi- (n = 69) and multiparous (n = 51) cows were scored for lesions and three claw measurements (dorsal wall length, heel depth, and toe angle) were recorded. Rates of lateral and medial claw growth and wear were calculated by measuring the migration of a reference mark away from the coronet. Digital photographs of claw surfaces were used to rescore claw lesions. Clinical lameness was evaluated by assigning a locomotion score from 1 to 4 to each cow during wk 1, 5, 10, and 14. Digital dermatitis (present/not present) and interdigital dermatitis (mild, moderate, or severe) were recorded at wk 15. The number of days that cows spent in a hospital barn was recorded. Before assignment, cows were professionally foot trimmed, sorted by initial claw lesion score, and then randomized in consecutive blocks of three to stall treatments. Photograph scores were highly repeatable. Nonparametric statistical techniques were used for analyses of rank data. Claw lesion score increased significantly for all treatment groups except RC and RS; however, when early lactation cows were excluded, no differences were found between treatment groups. Hock scores increased significantly more for cows in CtC than in CtS or RS. Significantly more animals from RC spent more than 10 d in the hospital pen compared with RM and RS. Groups did not significantly differ for clinical lameness. Cows in RS and RC had significantly lower rates for lateral claw net growth than those in CtM. Having moderate or severe interdigital dermatitis at wk 15 was associated with greater increases in claw lesion score and more treatments for digital dermatitis. All claw measurements were correlated; however, toe angle was most strongly correlated with the other two. In this experiment, stall and alley configurations did not lead to significant differences in several indices of lameness.

Effects of somatic cell count on quality and shelf-life of pasteurized fluid milk

Milk was collected from eight Holstein cows four times before and four times after intramammary infection with Streptococcus agalactiae. Postinfection milk had significantly higher somatic cell count (SCC) (849,000 cells/ml) than preinfection milk (45,000 cells/ml). High SCC raw milk had more lipolysis and proteolysis than low SCC raw milk. Pasteurized, homogenized, 2% fat milks from pre- and postinfection periods were stored at 5 degrees C and analyzed for lipolysis, proteolysis, microbial quality, and sensory attributes at 1, 7, 14, and 21 d post processing. During refrigerated storage, the average rates of free fatty acid increase (i.e., lipolysis) and casein hydrolysis in high SCC milk were, respectively, three and two times faster than those in low SCC milk. In general, standard plate counts, coliform counts, and psychrotrophic bacterial counts of both the high and low SCC milks remained low (<100,000 cfu/ ml) during 5 degrees C storage. Low SCC milk maintained high organoleptic quality for the entire 21-d shelf-life period. However, for high SCC milk, between 14 and 21 d, sensory defects were detected, which resulted in low overall quality ratings. The sensory defects mainly included rancidity and bitterness and were consistent with higher levels of lipolysis and proteolysis. Hence, mastitis adversely affected the quality of pasteurized fluid milk. It is recommended that the fluid milk industry consider implementation of premium quality payment programs for low SCC milks.

Effects of three prepubertal body growth rates on performance of Holstein heifers during first lactation

The effects of body weight (BW) gain, different sources of protein during the prepubertal period (90 to 320 kg of BW), and the performance of Holstein heifers during their first lactation were studied. Heifers (n = 273) were assigned to one of three dietary energy treatments that were designed to achieve average daily gains of 0.6, 0.8, and 1.0 kg/d. Within each energy treatment, different protein sources (plant protein and urea or both plant and animal proteins) were imposed. Actual average daily gains by heifers on each energy treatment were 0.68, 0.83, and 0.94 kg/d for heifers that were fed diets formulated for average daily gains of 0.6, 0.8, and 1.0 kg/d, respectively, which allowed the following ages at first calving: 24.5, 22.0, and 21.3 mo. Breeding was initiated when heifers weighed approximately 340 kg. Protein sources did not affect average daily gain or milk yield. Analysis of the preplanned comparisons of actual 305-d and 4% fat-corrected milk yields indicated that yield was significantly reduced for heifers grown at 0.94 kg/d (9387 and 8558 kg, respectively) compared with that of heifers grown at 0.68 kg/d (9873 and 9008 kg, respectively). However, further regression analysis of fat-corrected milk and residual milk from a test day model on prepubertal BW gain only explained 8 and 2% of the variation in milk yield, respectively. Postcalving BW and body condition score were different among treatments. Posttreatment factors, such as postcalving BW, accounted for more of the variation in milk yield than did prepubertal BW gain. Prepubertal BW gains, when evaluated on a continuum from 0.5 to 1.1 kg/d, explained little of the variation in milk yield; therefore, BW gain during the prepubertal period did not significantly affect milk yield during first lactation.

Evaluation of National Research Council and Cornell Net Carbohydrate and Protein Systems for predicting requirements of Holstein heifers

This experiment evaluated the effects of prepubertal energy intake and dietary protein source on average daily gain of Holstein heifers. Holstein heifers (n = 273) were assigned to one of three dietary energy treatments that were designed to achieve average daily gains of 0.6, 0.8, and 1.0 kg/d from 90 to 320 kg of body weight. Within each energy treatment, heifers were assigned to diets that were supplemented with animal and plant proteins or plant protein and urea. Diets were formulated using the Cornell Net Carbohydrate and Protein System. Actual mean daily gains by heifers on each energy treatment were 0.68, 0.83, and 0.94 kg/d and were not affected by protein source. Undegradable intake protein was predicted by the Cornell Net Carbohydrate and Protein System to be adequate to support the observed daily gain that was allowed by the amount of energy in the diet and was 13 to 25% lower than the recommendations for undegradable intake protein by the National Research Council. These results suggested that requirements for undegradable intake protein may be met at concentrations that are less than 35% of the dietary crude protein. Energy equations from the National Research Council and Cornell Net Carbohydrate and Protein System were evaluated and accounted for 87 and 86% of the variation in body weight gain that was allowed by the amount of energy in the diet with biases of -7.7 and -5.7%, respectively. The Cornell Net Carbohydrate and Protein System has the primary advantage of improved accuracy in the prediction of nutrient requirements in each unique production situation.

Use of prostaglandin F2 alpha as a postpartum reproductive management tool for lactating dairy cows

This study compared three programs for reproductive management of the postpartum period for reproductive performance and net economic benefit within three dairy herds (n = 1624 cows). Cows on one program received PGF alpha injection at 25 to 32 d postpartum for reproductive therapy, and cows on a second program received additional PGF2 alpha at 39 to 46 d postpartum for synchronization of estrus. These programs were compared with a postpartum program of rectal palpation based on veterinary intervention. Survival analysis indicated that cows receiving PGF2 alpha for reproductive therapy and synchronization of estrus had an 11% higher rate of first AI and 10% higher rate of pregnancy than did cows receiving the rectal palpation. No differences existed between the cows receiving rectal palpation and those receiving the PGF2 alpha. Because overall conception rates and conception rates at first AI did not differ among programs, the improved reproductive performance of cows receiving PGF2 alpha for both therapy and synchronization may be attributed to greater synchronization of estrus, which resulted in improved estrus detection. A partial budget indicated that the PGF2 alpha programs were less expensive than the rectal palpation program. When PGF2 alpha was used for postpartum reproductive therapy and synchronization of estrus, reproductive performance and net economic benefit were increased compared with those of the other programs.

Genetic parameters of Italian brown Swiss for levels of herd yield

Genetic parameters were estimated for yields and percentages of milk, fat, and protein for registered Italian Brown Swiss cows. Data were 72,690 mature equivalent 305-d first lactation yields split by herd average milk into four files. An expectation-maximization REML algorithm was used on a multiple-trait model with equal design matrices for fixed and random effects. Data were preadjusted for geographical area, age-month of calving, and days open. The model included herd-year and sire genetic group as fixed effects and sires as random effects. Estimates of heritability were .28, .30, .26, .42, and .34 for milk, fat, and protein yields, and fat and protein percentages, respectively. Genetic correlations of milk yield and milk component percentages were negative, as expected. Correlation of protein yield and protein percentage was null. Results show an increasing tend of variance components from low to high herd yields, indicating that dispersion of yield about the mean increases as average yield increases. Relative differences among environmental components were larger than those among genetic components, yielding larger estimates of heritability in herds with lower yield. Estimates of heritability for milk from low to high herd yields were .42, .38, .35, and .33.

Effects of premilking teat preparation on spores of anaerobes, bacteria, and iodine residues in milk

Premilking teat preparations using individual paper or cotton towels for either 6 or 20 s to reduce bacteria and iodine residues from teat surfaces were determined through Latin square designs applied to 50 cows. A cotton towel used for 20 s was most effective in cleaning teats, probably because of the physical structure of the towel, physical action on teat surface, and scrubbing of the teat ends. Premilking teat preparation of 6 s was inadequate to clean teats and to avoid iodine residues in milk. Teat end erosions increased iodine residue in milk. Two days after a treatment period, iodine content in milk from iodophor-dipped groups was similar to that of the undipped control group. Against our expectation, teat dipping with a .25% iodophor teat dip caused higher iodine residue in milk than a .50% iodophor teat dip. Differences in formulations and inert ingredients of iodophor teat dips indicate a need for further studies.

Effects of daily exogenous oxytocin on lactation milk yield and composition

Eighty-four Holstein cows were used to determine effects of exogenous oxytocin on 305-d milk production and health. Cows were assigned at parturition by parity group to treatments: 1) oxytocin group, animals received an injection of 1 ml (20 IU) of oxytocin at each milking throughout lactation and 2) control group, animals received no injection. Oxytocin injections were given in the thigh region within 3 min following the initiation of udder preparation and immediately prior to machine attachment. Udder preparation consisted of forestripping and manual cleaning (10 to 20 s) and drying (5 to 10 s) of teats. Cows were milked in a parlor, and milk yield was recorded at each milking. Milk samples were collected from each cow biweekly for milk fat, protein, and somatic cell count determination. Individual lactations were modeled using Woods' lactation equation; resulting coefficients were analyzed using ANOVA. The oxytocin group produced 849 kg more milk during the lactation than the control group, with a significant difference occurring after peak milk yield. This suggests that exogenous oxytocin maintained greater persistency during lactation. No significant differences existed for milk fat or protein percentages. The use of exogenous oxytocin at milking increased lactation milk production with no apparent effect on health.

Responses by lactating cows in commercial dairy herds to recombinant bovine somatotropin

Cows (890) in 15 US herds were assigned randomly in equal numbers to control or bST injections (500 mg in a prolonged-release form every 14 d for 12 wk) within three stages of lactation (57 to 100, 101 to 140, and 141 to 189 d postpartum) and two parity groups (primiparous and multiparous). Yield and milk composition were monitored 1 d/wk for 16 wk including 2 wk pretreatment and 2 wk posttreatment. Increases in milk and FCM due to bST injections were less at 57 to 100 d than at 101 to 189 d postpartum (milk 3.6 vs. 5.5; FCM 3.9 vs. 6.1 kg/d per cow), and increases in milk and FCM were more for multiparous than for primiparous cows (milk 5.5 vs. 4.2; FCM 6.0 vs. 4.7 kg/d cow). Temporarily, concentration of milk fat increased and protein decreased; later, concentrations for control and injected cows were similar. Postinjection milk fat concentration decreased, but milk protein concentration increased temporarily. The net increase in milk (and FCM) varied significantly among herds from 2.9 to 7.6 kg/d per cow (mean, 4.9 kg). Responses in FCM were similar over a wide range of pretreatment yields. A great variety of feed ingredients were fed as total mixed rations, and nutrient concentrations varied greatly. The SCC were similar before, during, and after treatment, but increase in FCM of injected cows exhibited a negative correlation with pretreatment SCC. Changes in body condition score of sometribove-injected cows varied among herds (.25 to -.45) and averaged -.02 compared with .07 for controls. There was no pattern in incidence of mastitis during sometribove injections.

Influence of bovine mastitis on lipolysis ond proteolysis in milk

Lipolysis and proteolysis in milk were determined before, during, and after experimentally induced mastitis. Streptococcus agalactiae was infused into one quarter of five cows to elicit an infection. Milk protease activity was higher during infection, but milk lipase activity was unchanged. Lipolytic damage to milk fat and proteolytic damage to milk casein occurred in the udder prior to milking during an infection. Lipolysis increased due to increased susceptibility of the milk fat to lipase action during infection. The mechanism of the increased susceptibility of the fat to lipolysis was not determined. After infections were eliminated, SCC, initial and stored FFA concentrations, and initial tryosine values returned to preinfection levels. However, after infections were eliminated, milk protease activity as determined by an increase in tryosine values remained elevated as milk SCC returned to preinfection levels. Protease activity returned to preinfection levels within 10 d after SCC returned to preinfection levels.

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.

Effects of prepartum milking on milk production and health performance

A field study using seven Holstein herds was conducted to determine effects of prepartum milking on milk production, health disorders, and reproductive performance. In each herd, 80 cows (30% first lactation cows) were assigned 1 mo prior to expected calving date to one of two treatments: postpartum or prepartum milking. The group milked prepartum was machine-milked twice daily at regular milking intervals beginning 14 d prior to date of expected calving. The group milked postpartum was milked for the first time after calving. The day prior to calving, 36, 33, and 31% of the cows milked prepartum produced less than 4.5 kg, 4.5 to 9 kg, and greater than 9 kg of milk, respectively. No relationship existed between days milked prepartum and prepartum milk yield. Lactation milk yield and persistency were not affected by prepartum milking. Prepartum milking reduced incidence of milk fever and mastitis during the 1st mo after parturition. Treatment was not a significant source of variation for reproductive performance or body condition; however, culling was higher for cows milked postpartum. Results indicate no adverse effects on cow performance due to prepartum milking nor increase in lactation milk yield.

Effect of mastitis on proteolytic activity in bovine milk

Proteolytic activity of milk was studied before, during, and after experimental-induced mastitis. An inoculum of Streptococcus agalactiae was infused into one quarter of each udder of six cows to elicit an infection. Bacteriological cultures and SCC of milk were used to monitor infection status. Sodium dodecyl sulfate-PAGE was used to measure proteolytic activity of milk. Inhibitor 6-amino-n-hexanoic acid was used to determine the relative proportion of plasmin and nonplasmin proteolytic activity of milk. Somatic cell count, total milk proteolytic activity, and nonplasmin proteolytic activity were higher in infected quarters than in quarters preinfection. After elimination of infections, SCC and nonplasmin proteolytic activity decreased to preinfection amounts. Total proteolytic activity of milk decreased after infections were cured but remained significantly higher than preinfection activity. This postinfection proteolytic activity in milk may be due to an increase in milk plasmin activity. Our data suggest that detrimental effects of mastitis on milk quality can continue after infection has been eliminated and milk SCC have returned to low values.

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.

Milk iodine residues in herds practicing iodophor premilking teat disinfection

The objective was to determine effects of different concentrations of iodophor teat dips on milk iodine residues, when teat dips were used both premilking and postmilking. Eighty cows in each of seven herds were assigned to one of four treatments. Each treatment received postmilking teat dip at .1 or 1% iodophor concentration. Two groups received no premilking dip, and the other two groups received premilking teat dip at the same concentration as the postmilking teat dip. Premilking teat dipping was followed by manual drying of teats. Noniodophor postmilking dips and no premilking inodophor udder sanitizers were used during an 8-d adjustment period. Milk was collected for milk iodine determination from each cow from weigh jars or milk meters at p.m. milkings during the last 3 d of the adjustment period and d 4, 6, and 8 of the treatment period. Premilking and postmilking teat dipping with .1% iodophor dip did not significantly increase milk iodine residue above postmilking teat dipping with .1% iodophor dip alone. However, 1% iodophor postmilking teat dip significantly increased milk iodine residue over use of .1% iodophor dip used as a premilking and postmilking teat dip. Adding a 1% iodophor premilking teat dip significantly increased iodine residues.

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.

Effects of premilking udder preparation on environmental bacterial contamination of milk

Premilking udder preparations varied wetness and cleanliness of udders and teats at machine attachment. In Experiment I, in a prep stall with manual drying of teats only, udder surface drainage during milking increased standard plate counts compared to preparations with dryer udder surfaces at machine attachment. In Experiment 2, use of prep stall only and no udder and teat preparation had higher standard plate counts than preparations by prep stall with manual drying of udder and teats and by wet paper towels in wetting and cleaning and dry paper towels in drying teats. No preparation of udder and teats had higher standard plate count attributed to soiled teats at machine attachment. Udder surfaces should be dry, and teats should be clean and dry at machine attachment. Premilking udder preparations can affect milk quality as measured by milk bacterial count.

Effects of vacuum and pulsation ratio on udder health

Effects of vacuum and pulsation ratio on udder health were studied for 36 first parity animals in a 60-day trial. Treatments consisted of vacuum at 33.3, 41.6, and 50 kPa at pulsation ratios of 50:50, 60:40, and 70:30 at 60 pulsations per min. All teats were exposed to a culture broth of Staphylococcus aureus after machine removal. Numbers of intramammary infections and somatic cells were determined. Analysis for number of intramammary infections indicated no significant differences among treatments for number of infected available quarters. Trend for intramammary infections was that as pulsation ratio widened, the number of infected available quarters increased, especially at the ratio 70:30. As vacuum increased, number of infected available quarters increased. Least squares means of Wisconsin Mastitis Test scores were 6.29, 5.57, and 6.68 for 33.3 kPa; 12.18, 3.82, and 7.86 for 41.6 kPa; and 9.11, 6.40, and 15.02 for 50 kPa at pulsation ratios 50:50, 60:40, and 70:30. There were significant differences among treatments for vacuum and pulsation ratio. Wisconsin Mastitis Test data indicated an interaction between vacuum and pulsation ratio. Optimum predicted vacuum and pulsation ratio based on Wisconsin Mastitis Test data were 27.2 kPa and 62:38.

Dairy herd reproductive health programs compared with traditional practices

Reproductive herd health programs have been advocated for many years, and rational approaches that are cost effective have been demonstrated. Dissemination of this information to dairymen can help create a demand for veterinary service. Similarly, the information can be utilized by veterinarians to encourage dairy clients to utilize profitable practices and programs. The study described demonstrated an improvement in biologic goals when a reproductive herd health program was incorporated into the management scheme. The program achieved economic success by reducing costs related to reproduction.