Biomedical subjects

R D Shanks

Publications and source records attributed to R D Shanks.

68 records · Page 4Linked to original sources

PubMed1984

Orotate in milk and urine of dairy cows with a partial deficiency of uridine monophosphate synthase.

Cows with a partial deficiency of uridine monophosphate synthase have elevated orotate in their milk and urine. Variability of orotate was assessed in two such cows monitored biweekly for two complete lactations. Concentrations of milk and urinary orotate showed extensive variation during lactation, but coefficients of variation were similar for deficient and normal cows. Orotate averaged 500 micrograms/ml milk for deficient cows (versus a normal of 80 micrograms/ml), and a threshold of 200 micrograms/ml distinguished normal from deficient cows. Deficient cows had low milk orotate upon initiation of lactation and exhibited a latency of 1 to 7 wk to attain that threshold. The deficiency also resulted in a lactation-induced orotic aciduria. Orotate averaged 32.2 micrograms/ml urine for deficient cows (versus a normal of 7.3 micrograms/ml), and a threshold of 15 micrograms/ml urine differentiated the animals. Latency was 3 to 18 wk for deficient cows to exceed that threshold. Total orotate output and orotate concentration were elevated in milk and urine of lactating cows deficient for uridine monophosphate synthase. The output of orotate was predominantly in milk rather than urine for both deficient and normal cows. Additionally, orotate was elevated in blood of deficient cows when they were lactating.

Animals↗

PubMed1983

Evidence for an oscillator other than luteinizing hormone controlling the secretion of progesterone in cattle.

The objective of this study was to quantify and compare the frequencies of pulses in ovarian and systemic concentrations of progesterone, systemic concentrations of luteinizing hormone (LH) and rate of ovarian blood flow. Blood was collected simultaneously from previously implanted catheters in the ovarian venous circulation and jugular vein on Day 12 or 13 of estrous cycles from 4 nonlactating dairy cows. Blood was collected at a rate of 2.5 ml/min for 5 min out of every 10 min over an 8-h period. The mean rate of blood flow in the ovarian artery during the 5-min collection period was estimated by an electromagnetic blood flow transducer. Pulses were observed over time in both ovarian and systemic concentrations of progesterone at frequencies that ranged between 0.625 and 0.875 cycles/h (1.1 to 1.5 h/cycle) among the animals. Only one or two episodes of release of LH were observed during the 8-h period, and transient increases in blood flow to the ovaries were associated temporally with each episode of LH release. The estimated frequencies for release of LH and increased blood flow were the same for each animal and ranged between 0.250 and 0.375 cycles/h. A second cycle with a frequency similar to that for LH was evident in the spectral density functions for ovarian and systemic concentrations of progesterone. This cycle was eliminated when the cycle for LH was removed from the data for progesterone, but the magnitude and frequency of the pulses in progesterone were not affected.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1983

A luteolytic interaction between estradiol benzoate and prostaglandin F2 alpha in cattle.

A possible luteolytic interaction between prostaglandin F2 alpha (PGF2 alpha) and estradiol benzoate (E2B) in cattle was investigated by randomly assigning 20 heifers to one of four groups of a 2 x 2 factorially designed experiment. The treatments for the groups consisted of im administration of: 1) 200 micrograms of E2B, given twice daily on d 10, 11 and 12 of the estrous cycle plus 7 mg PGF2 alpha, given at a separate site, but concurrently with the last injection of E2B; 2) the vehicles for E2B (sesame oil) and PGF2 alpha (saline); 3) E2B and saline and 4) sesame oil and PGF2 alpha. Administration of both E2B and 7 mg PGF2 alpha resulted in luteolysis as evidenced by a shorter mean length of the estrous cycle (P less than .05) when compared with the vehicle-treated control group, and a decline in systemic concentrations of progesterone to less than 1 ng/ml in four of five animals. Administration of PGF2 alpha with sesame oil was luteolytic in only one of five animals and E2B plus saline had no effect on the mean length of the estrous cycle or systemic concentrations of plasma progesterone. These observations suggested a luteolytic interaction between E2B and PGF2 alpha. This luteolytic interaction was examined further in a second experiment. Corpora lutea was removed 12 h after treatment with 200 micrograms E2B or .5 ml sesame oil, administered twice on d 10, 11 and 12 of the cycle, and incubated with luteinizing hormone (LH) and PGF2 alpha in vitro. The effect of both LH and PGF2 alpha was to increase progesterone synthesis (P less than .01), and this effect was observed irrespective of E2B pretreatment. These findings were not consistent with the hypothesis that the luteolytic site of action for either E2B or PGF2 alpha was inhibition of the steroidogenic effects of LH as assessed under in vitro conditions.

Animals↗

PubMed1983

Effects of formaldehyde treated soybean meal on milk yield, milk composition, and nutrient digestibility in the dairy cow.

The nutritional value of soybean meal that had been treated with formaldehyde (.3 g/100 g) to inhibit microbial degradation of soybean meal protein in the rumen was investigated. Four experimental diets were fed ad libitum during wk 4 to 43 of lactation to Holstein cows randomly assigned to diets in a 2 x 2 factorial arrangement of dietary crude protein (12 and 14%) and formaldehyde treatment (untreated and treated soybean meal). Concentrate, corn silage, and alfalfa-grass hay provided 53.0, 35.4, and 11.6% of the daily intake of dry matter. Analysis of covariance revealed that digestibility of dietary crude protein by cows fed formaldehyde treated soybean meal was lower than by cows fed untreated soybean meal (62.4 versus 65.4%). Similar quantities of milk, 4% fat-corrected milk, milk fat, and milk solids-not-fat (overall means of 7998, 7402, 281, and 660 kg/301 days of lactation) were produced by cows fed different diets. This was true whether the data were summarized during peak production (day 22 to 63), during days 22 to 119 when crude protein intake did not meet requirements, or during the complete experiment (days 22 to 301 of lactation). Milk protein (total nitrogen x 6.38) produced by cows fed soybean meal treated with formaldehyde was less than by cows fed untreated soybean meal during days 22 to 63 and during days 22 to 119 (47 versus 44 kg/cow and 103 versus 97 kg/cow). Changes in body weight of cows during lactation were similar among treatments. Treating soybean meal with .3 g formaldehyde/100 g may decrease availability of soybean meal protein for use by lactating dairy cows.

Ammonia↗

PubMed1983

Breeding practices on Illinois Holstein farms.

Questionnaires requesting breeding information were mailed to 1,148 Illinois Holstein herds in the Dairy Herd Improvement program. A total of 591 questionnaires (51%) were returned. Dairy producers with herds producing over 7,100 kg of milk returned 64% of their questionnaires whereas 34% of dairy producers with herds producing less than 5,900 kg returned their questionnaires. State average and standard errors were: 23 +/- 1 bulls used per 100 cows, 78 +/- 2% dairy producers select the bulls, 96 +/- 1% herds use artificial insemination, 2.1 +/- .1 artificial insemination organizations per herd, 29 +/- 2% herds participate in young sire testing programs, 87 +/- 1% farmers consider calving ease indicators in mating heifers, and 17 +/- 2% farmers consider calving ease indicators in mating cows. Breeding practices positively associated with increasing rolling herd average milk production were number of bulls per herd and per 100 cows, self as bull selector, use of artificial insemination, number of artificial insemination organizations, and participation in young sire testing programs. Three breeding practices were negatively associated with increasing rolling herd average milk production: artificial-insemination technician as bull selector and consideration of calving ease for mating heifers and cows. Dairy producers also were asked to rate the emphasis placed on traits in bull and cow selection. For bull selection, udder conformation and Predicted Difference milk were most important. In cow selection, milk production, followed by udder conformation, feet and legs, and fat percentage, was the most important trait.

Animals↗

PubMed1983

Relationships among lactation and reproduction traits of dairy goats.

Statistics for reproduction and lactation traits were estimated from 51,826 records of Alpine, La Mancha, Nubian, Saanen, and Toggenburg does. Means and standard deviations varied little across breed or lactation number. Relationships among reproduction and lactation traits were estimated from a subset of 42,618 records with 125 days or more in milk. Correlations also were stable across breed and lactation number. Regression analysis indicated a curvilinear relationship between lactation traits and reproduction traits.

Animals↗

PubMed1983

Effect of chlorpyrifos on Holstein steers and testosterone-treated Holstein bulls.

The effect of chlorpyrifos application was studied in a high-testosterone (testosterone-treated bulls) and a low-testosterone group (corn oil-treated steers). Frequent sampling of blood before and after 2 chlorpyrifos applications was used to monitor plasma testosterone concentrations and blood cholinesterase activities. Bulls had significantly higher testosterone concentrations (P less than 0.01) than did the steers, before and after the 1st and 2nd chlorpyrifos applications. Bulls had higher cholinesterase activities (P less than 0.01) than did steers before the 1st chlorpyrifos application. However, cholinesterase activity decreased more in bulls when compared with that in steers (P less than 0.01) after the 1st and 2nd chlorpyrifos application. Abnormal clinical signs were not observed in the steers, but 2 of 4 bulls had severe clinical signs of organophosphorus insecticide toxicosis after the 2nd application. Seemingly, chlorpyrifos is more toxic for testosterone-treated bulls than for corn oil-treated steers of similar age and weight.

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

Rare earth elements as markers for rate of passage measurements of individual feedstuffs through the digestive tract of ruminants.

Rumen and in vitro abomasal fluid incubations of four feeds, soybean meal (SBM), 0.3% formaldehyde-treated SBM, cottonseed meal and ground corn, each labeled with one of two markers (Sm and La) were conducted to estimate the extent of marker movement from the feeds. Feeds were marked by spraying acidic solutions of the marker movement from the feeds. Feeds were marked by spraying acidic solutions of the markers uniformly over the feeds. Concentration of marker on the feeds, on the feed residues remaining in polyester bags after 12 hours of incubation in the rumen, and on the feed residues after 12 hours of incubation in the rumen and 3 hours of in vitro incubation in abomasal fluid were determined by neutron activation. Initial concentration of the markers on the feeds was used as a covariable in analysis of the restricted randomized block design. Marker concentration of Sm and La, for all feeds, averaged 1115 +/- 44 and 1503 +/- 44 ppm after the rumen incubation and 959 +/- 54 and 1666 +/- 54 ppm after the combined incubations and differed (P less than 0.01) from the mean initial marker concentration of 1294 +/- 42 ppm. Abomasal incubations allowed estimation of marker movement (contamination) between bags. For both markers, increases (P less than 0.01) were observed in marker contamination when compared to initial levels. Marker contamination increased from 2.5 +/- 0.8 to 20.1 +/- 0.1 and 10.7 +/- 0.8 ppm for Sm and La, respectively. Data indicate significant marker movement and suggest that Sm and La, when applied to feeds by this method, are not suitable markers for estimating passage rates of individual feedstuffs.

Abomasum↗

PubMed1982

Projecting health cost from research herds.

Health costs by categories were summarized from 1,999 lactations of 863 cows in three dairy herds. These costs were projected to Dairy Herd Improvement data. Health categories were mammary, reproduction, locomotion, digestion, respiration, other, and total. The largest estimated total health cost of $67.63 was associated with postpartum length (days in milk and dry) greater than 420 days, an average 98 days dry, and milk production greater than 8,250 kg in fourth or later terminal lactations. The smallest estimated total health cost of $22.25 per lactation was associated with production between 5,750 and 6,999 kg in the nonterminal first lactation with postpartum length less than 300 days. For nonterminal first lactations of intermediate length, the estimated total health cost represented 3 to 6% of the value of milk production. First-calf heifers with milk production less than 5,750 kg and postpartum length 300 to 419 days had the least mammary cost. Cows in their fourth or later lactations with postpartum length greater than 420 days and milk production less than 5,750 kg had the highest reproductive cost. Mammary cost increased and reproductive cost decreased with increased days dry. Cows in terminal lactations had $11.38 more total health cost, $4.33 more mammary cost, and $6.31 more reproductive cost than cows in complete nonterminal lactations. Relatively more reproductive than mammary cost occurred in terminal lactations compared to nonterminal lactations. Mammary cost remained the largest component of total health cost. Multiparous cows had more total health, mammary, and reproductive costs than first parity cows. The repeatibility of total health cost was .12 +2- .03.

Animals↗

PubMed1981

Postpartum distribution of costs and disorders of health.

More than 17,000 events from 1,305 lactations of 551 cows in two herds were analyzed to quantify the distribution of costs and disorders of health during a lactation. Categories were mammary, reproduction, locomotion, digestion, respiration, other, insemination, and total. The largest costs and most disorders were associated with initiation of lactation rather than period of peak daily milk yield. Mammary and reproductive costs were 71% of total health cost in the first 30 days postpartum. Mammary and reproductive costs were 55% of the total health cost in an average 30-day interval. Insemination cost was 50% of the total health cost between 60 to 89 days postpartum. Parturition and extended days open were periods of large reproductive cost. Postpartum distributions of health cost and health disorders were similar implying that the prices assigned for severity added little information to counting disorders.

Animals↗

PubMed1981

Genetic aspects of lactation curves.

Parameters of lactation curves were defined by a gamma-type function for 113,705 lactations from the California Dairy Herd Improvement Association. Heritabilities and genetic correlations were estimated from a mixed-model analysis of paternal half sisters for first, second, third, and later lactations. Daily milk production on day 6 postpartum was estimated from production at first test-day to reduce the percentage of atypical lactations to less than 1% instead of an expectation of 30% without estimating production for day 6. The natural logarithm of the gamma-type function was ln(yt) = ln(a) + b ln(t) - ct, where yt was daily milk production in the tth week and ln(a), b, and c were coefficients. Persistency (c-(b+1)), week of peak yield (b/c), peak yield (a(b/c)be-b), and coefficient of determination were estimated from coefficients for each lactation. Heritabilities in first lactation were: ln(a) . 10 +/- .01, b .06 +/- .01, c .14 +/- .02, persistency .02 +/- .01, week of peak yield .02 +/- .01, peak yield .23 +/- .02, and determination .03 +/- .01. Heritabilities for later lactations were similar. Cows in first lactation had lower ln(a), lower peak yield, lower c, greater persistency, and took longer to reach peak yield than did cows in later lactations. Genetic and phenotypic correlations indicated that selection for increased peak yield would be associated with increased ln(a), b, and c without changing persistency or week of peak yield.

Animals↗

PubMedDate not supplied

Detection and prevalence of UMP synthase deficiency among dairy cattle.

A partial deficiency of UMP synthase has been detected in Holstein dairy cattle. Since affected females secrete milk with elevated concentrations of orotate, milk orotate was used to screen for the condition among 880 cows in 17 randomly selected Holstein herds in Illinois. Mean orotate was 85.0 +/- 1.5 microgram/ml milk and 17 cows had milk orotate in excess of 170 micrograms/ml. Including the latter animals, 42 cows were evaluated for erythrocyte UMP synthase and 15 were found to be partially deficient. Thus, at least 1.7 percent of all cows had the condition; this is a minimal estimate because the initial screen was milk orotate and this may be low, particularly early in lactation. Deficient cows had half the level of UMP synthase as normal, nondeficient cows (1.30 +/- 0.06 vs. 2.79 +/- 0.10 units/ml). The binomial classification of deficient versus normal accounted for 72 percent of the variation noted in UMP synthase. Milk orotate was significantly elevated in deficient cows (337.8 +/- 31.3 micrograms/ml), validating its use as a screening device. Urinary orotate also was higher for deficient cows (28.4 +/- 5.2 vs. 9.2 +/- 0.8 micrograms/ml) and differentiated the two groups as well as milk orotate. Normal and deficient cows did not differ in milk lactose concentrations. Erythrocyte UMP synthase also was measured in 85 Holstein bulls used for artificial insemination and 6 had low levels of UMP synthase (1.39 +/- 0.19 vs. 2.92 +/- 0.05 units/ml); the binomial classification accounted for 42 percent of the variation. The partially deficient animals identified appear to be heterozygotes for a condition expected to be lethal in the homozygous state.

Animals↗

PubMedDate not supplied

Inheritance of UMP synthase in dairy cattle.

The inheritance of uridine-5'-monophosphate (UMP) synthase in dairy cattle was consistent with a two-allele, single-autosomal-locus model. Two phenotypes were associated with different levels of the enzyme in bovine erythrocytes. The predominant phenotype (assumed normal) had twice the concentration of UMP synthase as the second phenotype (deficient). A one-to-one correspondence between enzyme level and genotype identified one homozygote as normal, the heterozygote as deficient, and the other homozygote as unobserved. Three alternative hypotheses were rejected. The deficiency as homozygous recessive was rejected because 20 matings between assumed normal males and deficient females resulted in 10 normal and 10 deficient offspring. The hypothesis that the deficiency was homozygous dominant was rejected because the 95 percent confidence interval about the observed gene frequency, 0.0024 to 0.0146, did not contain the estimated gene frequency for equilibrium between an average 10(-5) mutation rate and selection against the deficiency as homozygous dominant. Analyses of female relatives implicated one bull as deficient (96 percent probability), as he had, independently, 2 deficient daughters, 5 deficient granddaughters from untested dams, and 3 deficient great-granddaughters from untested ancestors. The hypothesis that the deficiency was sex-linked was rejected because 3 of 9 tested sons of the putative deficient bull were deficient. Calf mortality is expected in 25 percent of matings between deficient animals.

Alleles↗