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Biomedical subjects

S L Spahr

Publications and source records attributed to S L Spahr.

At least 19 recordsLinked to original sources
PubMed1992

Comparative responses of lactating cows to total mixed rations or computerized individual concentrates feeding.

A trial was conducted in a commercial dairy herd in which the concentrate part of the ration was fed individually to a group of cows through computerized self-feeders. Performance results were compared with those of a group fed TMR of 65 to 67% concentrates. Rationing of individual concentrates was according to parity, milk yield, milk yield potential, BW changes, and bunk feed-stuffs. Mean intake of concentrates per cow was about 1 kg/d lower in the individually supplemented cows. This was partly compensated for by a higher intake of bunk feedstuffs. Overall daily milk yield per cow was similar to those receiving a TMR in first parity cows, higher in second parity cows, and lower in third and greater parity cows. The higher performance of the second parity cows was achieved in all milk yield potential classes, and the lower yield in subsequent lactations was due to lower performance in low and high potential classes. The individually supplemented cows gained less BW than those in the TMR group. Milk yield per unit of BW was better than milk yield as a variable to refine individual cow supplementation strategy for allocation of concentrates. Results also suggest that the same criteria used for supplementation of concentrates can be beneficial to cows' assignments and movements among different TMR groups. Computerized dispensing of concentrates, when applied properly, can economize on consumption of concentrates when grouping and feeding different TMR are impossible.

Animal Feed↗
PubMed1991

Milk yield, parity, and cow potential as variables for computerized concentrate supplementation strategy.

A trial was conducted in a dairy of a cooperating kibbutz to investigate the cow's response to individual concentrate supplementation according to daily milk production when a feed mixture containing a 50:50 concentrate:forage offered in the bunk free choice. Concentrate supplementation was provided by computerized self-feeders for cows producing over 30 kg milk/d to a maximum of 10 kg/d concentrate (as fed) according to milk production. The results were compared with those cows fed, for ad libitum intake, a total ration of 73:27 concentrate: forage (high control) and 50:50 (low control). The performance variables of individually supplemented cows (milk yield, 4% FCM yield, and BW) were analyzed according to parity and milk yield potential. The results indicated that milk yield itself could not serve as the only variable for individual concentrate supplementation as applied in this experiment. Cows in different parities and with different milk yield potentials may respond differently to the concentrate supplementation strategy, and parity numbers, milk yield potential, and BW, in addition to daily milk yield, are possible variables to be considered when applying this feeding regimen in order to exploit its economic potential efficiently.

Animal Feed↗
PubMed1991

Activity monitoring and an enzyme immunoassay for milk progesterone to aid in the detection of estrus.

The accuracy and efficiency of estrus detection using an electronic activity monitor tag in conjunction with an enzyme immunoassay for milk progesterone were studied during 55 observed estrous periods in 37 cows. At approximately 30 d postpartum, cows were equipped with an activity tag and visually observed for estrus, an activity tag with a flashing light-emitting diode, or both twice daily. Milk progesterone concentrations were determined from cows observed in estrus or with an activated tag. Mean daily activity was greater on the day of estrus than during any of the 3 d preceding or 3 d following estrus. Functioning activity tags correctly identified 55% of all visually observed estrous periods that coincided with low milk progesterone levels. The overall accuracy of a flag by the tag for identifying true estrus was 21%. The enzyme immunoassay for milk progesterone was in agreement with 98% of all visually observed estrous periods and false flags committed by the tags. Although the activity tags detected some cows in estrus, a more durable and reliable tag must be developed before it is of practical value to dairy producers.

Algorithms↗
PubMed1989

Electrical conductivity of reproductive tissue for detection of estrus in dairy cows.

The pattern of temporal measurements of electrical conductivity obtained from electrodes that had been surgically implanted in the mucosa of the vagina or in the submucosa of the vulva in each of five dairy cows was evaluated for changes associated with the occurrence of estrus. Tissue conductivity was monitored at 6-h intervals during and around estrus by hard-ware devices operating at either 16 or 100 kHz. Blood samples were taken at time of conductivity measurement for progesterone determination and at 2-h intervals during estrus for LH determination. Vaginal and vulvar biopsies were performed during diestrus and estrus to measure tissue hydration. Conductivity increased significantly at estrus relative to a nonestrus base period in both vaginal and vulvar tissue. Both electrical frequencies were found to be satisfactory for characterizing changes in tissue conductivity associated with estrus. Peak concentrations of luteinizing hormone, increases in tissue hydration, and patterns of blood progesterone were consistent with the occurrence of estrus during the time of elevated tissue conductivity.

Animals↗
PubMed1985

Comparison of electrical conductivity of milk with other indirect methods for detection of subclinical mastitis.

Efficacy of detecting subclinical mastitis by electrical conductivity of milk was compared with that of other indirect methods including chloride, sodium, potassium, lactose, bovine serum albumin, and somatic cell count of milk. Quarter samples of foremilk, strippings, and bucket milk were obtained from 75 cows at the afternoon milking over 8 wk. Infection of quarters was ascertained by bacteriological analysis. Electrical conductivity, chloride, and sodium content of milk were more accurate for predicting infection status of quarters than were other variables. Most variables were more accurate in predicting infection when measures were in strippings rather than in foremilk or bucket milk. For measures in strippings, misclassifications by electrical conductivity were 11.2 and 15.5% for false positives and false negatives. The accuracy of the electrical conductivity of milk for detection of subclinical mastitis compared favorably with all indirect methods. Accuracy of detection and adaptability to both manual and automatic cow-side mastitis detection systems indicate that the method has considerable potential as a screening test for subclinical mastitis.

Animals↗
PubMed1983

Effects of milking interval on selected milk constituents from normal and infected quarters.

Effects of milking interval on electrical conductivity, chloride, sodium, potassium, lactose, and somatic cell counts of milk were determined. Quarter samples of foremilk, primary milk, and strippings were obtained from 12 cows after 3, 6, 9, 12, and 15-h milking intervals. The preceding interval to all experimental intervals was standardized at 12 h. Infection status of quarters was ascertained by bacteriological analysis. Effect of milking interval was significant on all variables measured. Highest conductivity, chloride, sodium, and cell counts were at the 3-h interval but declined to their lowest at the 9-h interval. Conductivity, chloride, and sodium then steadily increased from 9 to 15 h. Lactose followed the opposite trend and was highest at the 9-h interval. Trend was similar in samples from both uninfected and infected quarters; however, changes were more pronounced in the latter. Change of conductivity from infection varied with type of sample and milking interval with strippings being the most sensitive. All samples were least sensitive to these changes at the 9-h interval. Conductivity measurements on strippings will be more sensitive for detecting mastitis than measurements from foremilk or primary milk, especially measured following short milking intervals.

Animals↗
PubMed1983

Influence of the estrous cycle on selected biochemical and cytologic characteristics of milk of cows with subclinical mastitis.

The purpose in this experiment was to determine the relationship between subclinical mastitis and the estrous cycle. Subclinical mastitis was defined as a quarter in which milk had a somatic cell concentration greater than 500,000/ml and was bacteriologic culture-positive on 2 consecutive examinations. Normal quarters were defined as quarters from which milk had a somatic cell concentration less than 500,000/ml and was bacteriologic culture-negative on 2 consecutive examinations. Selected biochemical and cytologic characteristics of milk from 10 cows with subclinical mastitis were measured at 5-day intervals during the estrous cycle. Milk and blood progesterone concentrations were determined. Analysis of variance of dependent variables was performed, using a model with the following factors: cows, treatments, days of estrous cycle, and interaction of treatment with day of the estrous cycle. Treatment consisted of comparison of normal and subclinically mastitic quarters. Clinical signs of mastitis tended to occur more often during estrus (days 0 and 20) than during diestrus (day 10). Day of the estrous cycle was a significant source of variation for bovine serum albumin concentrations in milk. Somatic cell concentrations, electrical conductivity, milk bacterial concentrations, and log10 milk bacterial concentrations did not vary significantly during days of the estrous cycle. A significant treatment-by-day interaction occurred for milk progesterone concentrations; blood progesterone concentrations were not similarly affected. Milk progesterone concentrations for mastitic and normal quarters were similar at estrus (days 0 and 20) and metestrus (day 5). Milk progesterone concentrations for mastitic quarters were significantly decreased on day 15 of the estrous cycle, compared with values from normal quarters.

Analysis of Variance↗
PubMed1982

Diagnosis and treatment of acute mastitis in a large dairy herd.

In a 270-cow dairy herd, milk samples from all cows with acute mastitis were cultured during a 12-month period. Of 119 isolates (from 166 quarters), 49% were gram-positive organisms, 39% were gram-negative organisms, and 12% were yeasts. Of all samples from cows with acute mastitis, 40% failed to produce colonies on culture media. Recovery of the common gram-positive pathogens, Staphylococcus aureus (11% of isolations) and Streptococcus agalactiae (1% of isolations), was rather low. However, S epidermidis (14% of isolations) and streptococci other than Str agalactiae (9% of isolations) were recovered more frequently than expected, particularly in recently calved cows. Coliform organisms accounted for 35% of the total isolates and were the single most important cause of acute mastitis. Of 42 cows with coliform mastitis, 6 died despite intensive antibiotic and electrolyte therapy. There was no death loss among cows with mastitis caused by gram-positive organisms. Antimicrobial susceptibilities of 95 isolates to 11 antimicrobials was determined by standardized methods. Organisms were most often susceptible to chloramphenicol, cephalothin, and gentamicin. A treatment regimen consisting primarily of oxytetracycline and/or sulfonamides systemically in conjunction with intramammary infusions of cephapirin was evaluated. Treatment response in 37 quarters was determined by culturing before treatment and at 4 or more days after treatment. Of 23 quarters initially culture-positive, 22 were negative on reculture. Treatment response appeared to agree with the results of the susceptibility testing.

Acute Disease↗
PubMed1982

Electrical conductivity of milk for detection of mastitis.

The potential value of electrical conductivity of milk as a screening test for subclinical mastitis was evaluated. Conductivity of foremilk and of postmilking strippings from 368 quarters of 92 cows was measured. Infection status of quarters was determined by bacteriological analysis of strict foremilk samples. Infections were classified as by primary or secondary pathogens, depending on the importance of the isolated organism as a mastitis pathogen. Somatic cells were counted on foremilk samples. Milk conductivity increased with infection. Conductivity of postmilking strippings was higher than that of foremilk in samples from quarters infected by primary pathogens. By thresholds which correctly classified at least 90% of normal quarters, accuracy of identifying primary pathogen infections by absolute conductivity was 62.8 and 96.2% with foremilk and postmilking strippings. Differential conductivity and combination of absolute and differential methods also were evaluated with the latter being the most effective. Number of quarters with elevated conductivity of postmilking strippings tended to be higher when somatic cell count was greater than 500,000/ml in both normal and infected groups. Conductivity of milk seems to hold promise as an indicator of subclinical mastitis.

Animals↗
PubMed1982

Milk progesterone for pregnancy diagnosis in dairy goats.

Factors affecting progesterone concentration in milk of lactating dairy goats and use of this milk for pregnancy diagnosis were studied. Radioimmunoassay was used to assay progesterone in milk. Mean milk progesterone (ng/ml) +/- standard errors of 6 pregnant does for first, composite, and last milk were 9.9 +/- 2.0, 18.2 +/- 3.5, and 21.7 +/- 4.1. Correlation between milk fat and progesterone in composite milk was low (.11). Composite milk samples from 4 nonpregnant does were obtained daily throughout the estrous cycle. Milk progesterone (ng/ml) was 1 to 2 at estrus, rose to 5 to 12 within 2 to 5 days, reached a plateau at 15 to 25 in the middle of the estrous cycle, and then dropped to low concentrations again at 3 to 5 days before the next estrus. Milk progesterone also was used to diagnose pregnancy in 72 does. Forty-two does were diagnosed pregnant by high progesterone; 36 of these does later produced kids, and 5 other does aborted in various stages of pregnancy. Of 21 does diagnosed not pregnant with low progesterone, 19 does were not pregnant by either return to estrus or lack of parturition in the spring. All three incorrectly diagnosed does were problem breeders. Nine does with intermediate milk progesterone were classified questionable. Milk progesterone can be used to provide an early indication of the pregnancy status of does.

Animals↗
PubMed1981

Influences on progesterone concentration in bovine milk.

Factors affecting progesterone concentrations in milk of lactating dairy cows were studied and discussed as they pertained to pregnancy diagnosis. Adding a preservative to milk allowed storage at room temperature for 10 days with no effect on progesterone analysis. Progesterone content in first, composite, and last milk was associated with fat content, although correlation between progesterone concentration in composite milk and fat percentage was low. Variation was considerable in individual samples for each of the milk fractions. Day of the estrous cycle was the most important factor affecting progesterone concentration in milk from cycling cows. Samples for pregnancy diagnosis by milk progesterone should be collected near the time that nonpregnant cows are expected to return to estrus. Progesterone concentration in milk from pregnant cows remained high throughout gestation with progesterone concentrations similar to those in the luteal phase of the estrous cycle.

Animals↗
PubMed1981

Effect of length of milking interval and fat content on milk conductivity and its use for detecting mastitis.

Foremilk and strippings were obtained from 20 cows at the morning and evening milkings where the milking intervals were 14 h and 10 h. Infection status was determined by bacteriological analysis. Conductivity of foremilk and strippings was determined. Cows then were switched to 12 h milking interval, and conductance of foremilk and strippings from both milkings was determined. Conductance of foremilk samples increased after longer milking interval. Accuracy in detecting infections by primary pathogens via conductivity of foremilk was also greater following the long interval. Conductivity of foremilk from morning and evening milkings were, however, similar when the milking interval was even. Conductivity of strippings was affected less by milking interval. Conductance determination on quarter samples from 28 cows on both a whole and fat-free basis indicated an inhibitory effect of milk fat on conductivity. Conductivity of skimmed strippings samples was greater than that of skimmed foremilk samples, indicating higher electrolyte in strippings, and may explain why conductivity of strippings is not significantly lower than of foremilk in spite of the higher fat content in the former

Animals↗
PubMed1980

Methane production from cattle waste in laboratory reactors at 40 degrees and 60 degrees C after solid-liquid separation.

Whole dairy waste and liquid effluent separated from the same waste with a solid-liquid separator were fermented at mesophilic and thermophilic temperatures. Chemical analyses of the two materials were similar. Methane production was superior in thermophilic reactors. With subtrates adjusted to 4.1% volatile solids, average methane production at 60 degrees C (166 ml/g volatile solids fed to reactors at 3- and 6-day retention time) was as efficient as the 40 degrees C (162 ml/g at 5- and 10-day retention times). Thermophilic reactors produced 1.67 liter methane/liter reactor per day as compared to .93 liter for mesophilic reactors. Efficiency of methanogenesis was no greater for whole waste than for separated effluent. Production of methane for the two substrates averaged over retention times and temperatures was 156 ml/g volatile solids fed to reactor for whole waste and 173 ml/g for separated effluent.

Animals↗
PubMed1979

Mastitis history, California Mastitis Test, and somatic cell counts for identifying cows for treatment in a selective dry cow therapy program.

Mastitis history, California Mastitis Test scores, and filter-deoxyribonucleic acid cell counts from 232 cows were used to project the effectiveness of criteria which could be used to determine which cows to treat in a selective dry cow therapy program. Bacteriological analyses of quarter milk samples were used to identify infected cows. Effects of month, lactation parity, stage of lactation, and interaction of stage of lactation with lactation parity on somatic cell numbers in milk were determined. The various criteria singly or in combinations correctly identified from 50 to over 92% of the cows with one or more infected quarters at drying off. However, from 25 to 80% of the cows free of infection would have been treated as well. The most discriminating criteria were two monthly cell counts exceeding 500,000 cells per milliliter where 53% of the cows with infected quarters were identified correctly and only 25% of the uninfected cows would be treated, or the two monthly cell counts exceeding 500,000 cells per milliliter plus a California Mastitis Test score of +2 or +3 at drying off. Here 89% of the cows with infected quarters would be treated, and 56% of the uninfected cows would be treated.

Animals↗
PubMed1978

Complete versus selective dry cow therapy for mastitis control.

Two hundred and thirty-two cows were assigned alternately to complete dry cow therapy (infusion in all quarters on the day of drying off) or selective therapy (infusion in all quarters if a history of mastitis, California Mastitis Test score of +2 or +3 in any quarter, or if cell counts from bucket milk samples as determined by the membrane filter-deoxyribonucleic acid procedure were above 500,000 cells/ml). A dry cow product containing 10(6) units of procaine penicillin G and 1 g of dihydrostreptomycin in a slow release base was used. A 1% iodophor teat dip was used throughout the experiment. Infections of Staphylococcus aureus, Streptococcus agalactiae, other streptococci, and gram negative rods were eliminated from 85.4% of the infected quarters with complete therapy and 88.2% of the infected quarters with selective therapy. New infections occurred in 3.1% of quarters with complete therapy and in 6.5% of the quarters with selective therapy. Incidence of mastitis following the dry period was less with complete therapy compared to selective therapy (4.6% vs. 7.8% of the quarters). Selective therapy was as effective as complete therapy in eliminating existing infections. Complete therapy would be the choice in situations where new infections in dry period are of concern.

Animals↗
PubMed1976

Prenancy diagnosis in dairy cattle by progesterone concentration in milk.

Concentration of progesterone in whole milk was used to diagnose pregnancy in lactating dairy cows. Milk samples were taken 21 to 22 days postbreeding and analyzed for progesterone by radioimmunoassay. Progesterone in milk greater than 11 ng/ml, 8 to 11 ng/ml, and less than 8 ng/ml was used classify animals as pregnant, questionable, and not pregnant. In this classification for 123 cows, 67 were classified pregnant, 7 questionable, and 49 not pregnant. A comparison of progesterone diagnosis with actual calving results showed agreement of 73 and 98% for the cows classified as pregnant and not pregnant. Thirteen of 19 animals, in which there were discrepancies between diagnoses by milk progesterone and calving results, were not detected in estrus within 30 days after breeding. One animal classified not pregnant by milk progesterone was pregnant.

Animals↗