Biomedical subjects

S L Spahr

Publications and source records attributed to S L Spahr.

29 records · Page 2Linked to original sources

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

Effect of repeated superovulation on ovulatory response of dairy cows.

Explore the source record for details and available documents.

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↗

PubMed1974