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PubMed1994

The diagnostic yield of intravenous urography: a demographic study.

OBJECTIVE: To examine the impact of intravenous urography (IVU) on patient management in unselected patients in an effort to identify groups in which the use of urography could be reduced. PATIENTS AND METHODS: The results of IVU in 235 consecutive unselected patients were assessed prospectively to establish the value of IVU in patient management. Patients were divided into subgroups on the basis of age, sex, presenting symptoms and source of referral. The percentage of examinations with findings affecting patient management was taken as the 'positive diagnostic yield.' Differences between the positive diagnostic yields of IVU in the various groups were examined using the chi 2 test. RESULTS: For all patients the diagnostic yield was 37.4%. In patients over 50 years of age the yield was 46% while below that age the yield fell to 20%. This difference was significant (chi 2 = 13.88, P < 0.001). There were no significant differences between the other defined groups. Specifically, patients referred by general practitioners were as likely to have an IVU abnormality as were patients referred by a hospital practitioner. Patients with painless microscopic haematuria had a lower diagnostic yield (20%) than the other groups examined but this was not significant. CONCLUSION: IVU has a high diagnostic yield in an unselected population. Although the yield is lower in younger patients IVU offers advantages over other techniques in the investigation of urolithiasis--the commonest positive diagnosis in this study. We argue that it should retain its position as the primary investigation for the majority of patients with urological disease, particularly those suffering loin pain or haematuria.

Adolescent↗
PubMed2006

Comparison of peripheral blood progenitor cell yield from standard chemotherapy used in the treatment of lymphoid malignancies and high-dose cyclophosphamide: a retrospective review of 141 patients.

BACKGROUND: Peripheral blood progenitor cells (PBPCs) are often collected after mobilization with high-dose cyclophosphamide (HDC) combined with growth factors. HDC may not be needed for PBPC mobilization, and patients with lymphoid malignancies can be harvested with treatment regimens of chemotherapy. STUDY DESIGN AND METHODS: A retrospective analysis was performed on 141 patients with lymphoma or multiple myeloma whose PBPCs were harvested after chemotherapy. The PBPC yield and time to mobilization was compared between patients who received HDC (n = 51) and other chemotherapy regimens (n = 90) including high-dose cyclophosphamide and etoposide (HDC plus VP-16; n = 41), CHOP, ESHAP, ABVD, VAD, and others (n = 49). A multiple linear regression model and proportional hazards model determined factors influencing yield and time to mobilization, respectively. RESULTS: The difference in mean yield between HDC and all non-HDC regimens was significant, with HDC plus VP-16 resulting in the highest yields. The proportion of patients achieving a CD34 count in excess of 5 x 10(6) per kg did not differ significantly between the regimens. In a multiple linear regression model, HDC plus VP-16 resulted in a higher PBPC yield than HDC but all other regimens did not. In addition, patients exposed to more than one prior chemotherapy regimen had lower yield regardless of the mobilization regimen. The mean number of days to mobilization with HDC was 10.2 days, 17.1 days for HDC plus VP-16, and 14.2 days for all other regimens. The timing of mobilization was influenced by the chemotherapy used and the number of prior regimens in a proportional hazards model. CONCLUSION: These results demonstrate a higher mean yield of PBPCs with HDC plus VP-16 but no difference in yield between non-HDC plus VP-16 regimens used for first-line or relapse therapy and HDC, suggesting that HDC may be an unnecessary additional therapy.

Adult↗
PubMed2004

The use of phenotypic correlations and factor analysis in determining characters for grain yield selection in chickpea (Cicer arietinum L.).

To our knowledge, this is the first report on the use of factor analysis in determining characters for yield selection in chickpea (Cicer arietinum L.). The present investigation was undertaken to evaluate yield criteria in chickpea using phenotypic correlations and factor analysis. Factor 1 composed of biological yield, reaction to ascochyta blight (Ascochyta rabiei (Pass.) Labr.), plant height, grain yield and harvest index. Factor 2 consisted of branches and pods per plant. Factor 3 encompassed of only the grain weight. The total factors explained 92.9% of the total variance caused in the characters. The grain yield was positively and statistically significant correlated with biological yield, harvest index, plant height, branches and pods per plant, while it was negatively and statistically significant related with reaction to ascochyta blight and grain weight. Biological yield, harvest index, plant height and reaction to ascochyta blight instead of many selection criteria should previously be evaluated in selection to increase the grain yield in chickpea breeding programs. Pods per plant should be handed together with and branches per plant. Apart from the other selection criteria, the grain weight should solely be evaluated to select large grained genotypes.

Ascomycota↗
PubMedDate not supplied

Determination of specific yield for the Biscayne Aquifer with a canal-drawdown test.

Data from a large-scale canal-drawdown test were used to estimate the specific yield (sy) of the Biscayne Aquifer, an unconfined limestone aquifer in southeast Florida. The drawdown test involved dropping the water level in a canal by about 30 cm and monitoring the response of hydraulic head in the surrounding aquifer. Specific yield was determined by analyzing data from the unsteady portion of the drawdown test using an analytical stream-aquifer interaction model (Zlotnik and Huang 1999). Specific yield values computed from drawdown at individual piezometers ranged from 0.050 to 0.57, most likely indicating heterogeneity of specific yield within the aquifer (small-scale variation in hydraulic conductivity may also have contributed to the differences in sy among piezometers). A value of 0.15 (our best estimate) was computed based on all drawdown data from all piezometers. We incorporated our best estimate of specific yield into a large-scale two-dimensional numerical MODFLOW-based ground water flow model and made predictions of head during a 183-day period at four wells located 337 to 2546 m from the canal. We found good agreement between observed and predicted heads, indicating our estimate of specific yield is representative of the large portion of the Biscayne Aquifer studied here. This work represents a practical and novel approach to the determination of a key hydrogeological parameter (the storage parameter needed for simulation and calculation of transient unconfined ground water flow), at a large spatial scale (a common scale for water resource modeling), for a highly transmissive limestone aquifer (in which execution of a traditional pump test would be impractical and would likely yield ambiguous results). Accurate estimates of specific yield and other hydrogeological parameters are critical for management of water supply, Everglades environmental restoration, flood control, and other issues related to the ground water hydrology of the Biscayne Aquifer.

Calcium Carbonate↗
PubMed1978

Molar growth yields and enterotoxin B production of Staphylococcus aureus S-6 with amino acids as energy sources.

Staphylococcus aureus S-6 was able to utilize glutamate, proline, histidine, aspartate, alanine, threonine, serine, or glycine as a major energy source, when these were added singly at a concentration of 2.5 g/liter to a base medium containing salts, vitamins, and 30 mg of each of 18 amino acids per liter. Molar growth yields (Y) for each of the eight amino acids were determined in aerobic batch cultures. Except with aspartate and serine, all molar growth yields decreased with increasing concentration of the energy source, whether or not it was present in excess. The average molar growth yields for both aspartate and serine were Y = 35 g/mol. The highest Y values obtained with the other amino acids were 79, 78, 56, 46, 58, and 21 g/mol for glutamate, proline, histidine, alanine, threonine, and glycine, respectively. Histidine was not utilized as an energy source at concentrations of less than 2 mM. Enterotoxin yields (mg of toxin per g [dry wt] of cells) higher than in the basal medium were obtained when proline, histidine, alanine, serine, and glycine were the major energy sources. When proline and alanine were the major energy sources, enterotoxin yields were not affected by the concentration, whereas toxin yields were reduced at high concentrations of the other six amino acids. The highest cell yields and Y values were obtained with glutamate, but its utilization as an energy source markedly reduced enterotoxin yields.

Amino Acids↗
PubMed1993

Tar yield of cigarettes and risk of acute myocardial infarction. GISSI-EFRIM Investigators.

OBJECTIVE: To analyse the relation between tar and nicotine yield of cigarettes smoked in the recent past and the risk of myocardial infarction. DESIGN: Multicentre case-control study conducted between September 1988 and June 1989. SETTING: Over 80 coronary care units in various Italian regions. SUBJECTS: 916 patients with acute myocardial infarction without history of ischaemic heart disease and 1106 controls admitted to hospital for acute conditions not related to known or suspected risk factors for ischaemic heart disease. MAIN OUTCOME MEASURES: Relative risk of myocardial infarction according to type of cigarette smoked adjusted for identified potential confounding factors. Brands of cigarettes classified according to yield of tar and nicotine. RESULTS: Patients with acute myocardial infarction were more often smokers and among smokers they tended to smoke more cigarettes. Compared with non-smokers their estimated relative risks were 3.8, 4.3, 3.2, and 3.7 in the four categories of tar yield (< 10, 10-15, > 15-20, and > 20 mg, respectively). No trend in risk across yields was evident when analysis was restricted to smokers and allowance was made for number of cigarettes. Compared with risks in subjects in the lowest category of tar yield the relative risks were 1.2, 0.8, and 1.0 for the subsequent yields. Compared with risks in non-smokers the relative risks ranged from 9.3 to 12.6 below the age of 50 but no trend was observed with increasing yield. CONCLUSIONS: Changing to cigarettes with a lower tar yield is not an effective means of reducing tobacco related morbidity from myocardial infarction.

Adult↗
PubMed1984

Relative intakes of tar, nicotine, and carbon monoxide from cigarettes of different yields.

The relative intakes of tar, nicotine, and carbon monoxide were estimated in 2455 cigarette smokers, who freely smoked their usual brands of cigarette. The estimates were derived by using an objective index of inhaling based on the measurement of carboxyhaemoglobin divided by the carbon monoxide yield of the cigarettes smoked, after background and carry over carboxyhaemoglobin effects had been allowed for. Separate analyses were performed according to the yield and type (plain, filter, etc) of cigarette smoked. The analyses based on yield indicated that the extent of inhaling was adjusted sufficiently to achieve similar intakes of nicotine/carbon monoxide regardless of the nicotine/carbon monoxide yield. It was not, however, sufficiently increased to achieve a similar intake of tar as the tar yield of the cigarette decreased. The analyses based on type of cigarette indicated that the extent of inhaling was adjusted to achieve similar intakes of tar and nicotine regardless of the type of cigarette smoked, but that this led to a greater intake of carbon monoxide among filter cigarette smokers than that among smokers of plain cigarettes--more so than would have been expected from their relative carbon monoxide yields. Two conclusions arise from these results. Firstly, any harmful effects of nicotine/carbon monoxide are unlikely to be materially reduced by smoking cigarettes with lower yields of nicotine/carbon monoxide, but the harmful effects of tar are likely to be reduced by smoking cigarettes with lower tar yields. These predictions appear to be borne out by epidemiological observations. Secondly, any harmful effects of carbon monoxide on the cardiovascular system will be greater in smokers of modern filter cigarettes than in smokers of modern plain cigarettes, provided that these two groups of smokers are otherwise similar with respect to risk of cardiovascular disease.

Adult↗
PubMed1995

The tar reduction study: randomised trial of the effect of cigarette tar yield reduction on compensatory smoking.

BACKGROUND: Observational and short term intervention studies have reported that smokers of low tar cigarettes inhale more deeply (that is, compensate) than those who smoke high tar cigarettes. To quantify this effect a long term randomised trial was conducted on the effects of switching to low tar cigarettes. METHODS: The trial was carried out between April 1985 and March 1988 among cigarette smokers in the British Civil Service, measuring blood carboxyhaemoglobin (COHb) levels and serum cotinine levels as markers of tobacco smoke intake. Volunteers first switched to a cigarette brand yielding around 10% less tar than their usual brand to identify smokers able to change brand. The 434 subjects who successfully switched were then randomly allocated to one of three groups: (a) "fast reduction" group which changed to a brand of cigarettes with a tar yield of about half that of their usual brand; (b) "slow reduction" group which reduced to the same level in steps over several months; and (c) a control group which continued smoking cigarettes with a tar yield 10% lower than their usual brand. RESULTS: Over the course of the trial cigarette consumption declined slightly in all three groups. In both the "fast reduction" and the "slow reduction" groups, intake of COHb and cotinine was reduced, though not to the same extent as the yield reduction. Comparison of the results before randomisation with those at the end of the trial showed that a reduction in carbon monoxide yield of 45% was associated with a decrease in carbon monoxide intake of 19% (95% confidence interval 14% to 24%) and that a reduction in nicotine yield of 40% was associated with an 11% (6% to 16%) reduction in nicotine intake, reflecting relative intakes of about 1.5 for both carbon monoxide and nicotine in the "fast reduction" group. Results were similar in the "slow reduction" group with a 42% reduction in carbon monoxide yield, a 16% (11% to 22%) reduction in carbon monoxide intake, a 37% reduction in nicotine yield, and a 6% (0% to 13%) reduction in nicotine intake. Estimates of compensation derived from these results were 65% for carbon monoxide, 79% for nicotine, and 62% for tar. CONCLUSIONS: Compensation, demonstrated when switching from a high tar cigarette to a low tar one, was incomplete. Advising people who have failed to give up smoking to switch to low tar cigarettes will reduce the intake of smoke constituents to a small extent. This would be expected to decrease their risk of smoking-related diseases, although by a smaller amount than would be achieved by giving up smoking altogether.

Adaptation, Psychological↗
PubMed2004

Smoking cigarettes of low nicotine yield does not reduce nicotine intake as expected: a study of nicotine dependency in Japanese males.

BACKGROUND: Many Japanese believe that low-yield cigarettes are less hazardous than regular cigarettes, and many smokers consume low-yield cigarettes to reduce their risks from smoking. We evaluate the association between actual nicotine intake and brand nicotine yield, and the influence of nicotine dependence on this association. METHODS: The study subjects included 458 Japanese male smokers, aged 51.2 +/- 9.9 years, who participated in health check-ups in a hospital in 1998 and 2000. Each subject filled out a self-administered smoking questionnaire and the score of each on the Fagerström Test for Nicotine Dependence was calculated. Urinary cotinine concentration was measured at the time of participation. RESULTS: The geometric mean of urinary cotinine concentration was 535 ng/mgCr for those who smoked brands with the lowest nicotine (0.1 mg on the package), compared with 1010 ng/mgCr for those who smoked brands with the highest (0.9-2.4 mg, weighted mean of 1.1 mg). Thus, despite the 11-fold ratio of nicotine yield on the packages, the ratio of urinary cotinine level was less than twofold. Both nicotine yield on the package and nicotine dependence significantly increased urinary cotinine concentration, and the negative interaction between them almost attained statistical significance. Cotinine concentration in heavily dependent smokers was consistently high regardless of the nicotine yield of brands. CONCLUSIONS: The nicotine yield of cigarettes measured by machine-smoking does not reliably predict the exposure of smokers. Smokers consuming low-yield nicotine cigarettes did not reduce actual intake of nicotine to the level that might be expected, especially for those heavily dependent on nicotine. Current labeling practices are misleading for the two-third of smokers who are moderately or highly dependent on nicotine.

Adult↗
PubMed2005

Prediction of potential mushroom yield by visible and near-infrared spectroscopy using fresh phase II compost.

Potential mushroom (Agaricus bisporus) yield of phase II compost is determined by interactions of key quality parameters including dry matter, nitrogen dry matter, ammonia, pH, conductivity, thermophilic microorganisms, C : N ratio, fiber fractions, ash, and certain minerals. This study was aimed at generating robust visible and near-infrared (Vis-NIR) calibrations for predicting potential yield, using spectra from fresh phase II compost. Four compost comparative trials were carried out during the winter and summer months of 2001-2003, under controlled experimental conditions employing six commercially prepared composts, with eight replicate (8 bag) plots per treatment (48 x 8 = 384). The substrates were prepared by windrow or bunker phase I, followed by phase II production. The fresh samples were scanned for Vis-NIR (400-2498 nm) spectra, averaged, transformed, and regressed against the recorded yield by employing a modified partial least squares algorithm. The best calibration model generated from the database explained 84% of yield variation within the data set with a standard error of calibration of 13.75 kg/tonne of fresh compost. The model was successfully tested for robustness with yield results obtained from a validation trial, carried out under similar experimental conditions in early 2004, and the standard error of prediction was 18.21 kg/tonne, which was slightly higher than the mean experimental error (17.94 kg/tonne) of the trial. The accuracy of the model is acceptable for estimating potential yield by classifying phase II substrate as poor (180-220 kg), medium (220-260 kg), and high (260-300 kg) yielding compost. The yield prediction model is being transferred to a new instrument based at Loughgall for routine evaluation of commercial phase II samples.

Agaricales↗
PubMed2001

Response of potato tuber yield to stem injury by European corn borer (Lepidoptera: Crambidae) in the Mid-Atlantic United States.

The response of potato, Solanum tuberosum L., tuber yield to stem injury by European corn borer, Ostrinia nubilalis (Hübner), larvae was investigated in the Mid-Atlantic region of the United States for 3 yr. This response was described for 'Superior', 'Atlantic', and 'Snowden' potato, which are early-season, midseason, and late-season maturing cultivars, respectively. To model the yield/injury relationship, a range of corn borer injury levels was established in the field by augmenting the natural infestation with varying densities of laboratory-reared larvae. Linear and nonlinear regression analyses (plateau and second-order polynomial models) were used to describe the relationship between yield of U.S. No. 1 grade tubers and the percentage of stems injured by corn borer larvae. The maturity of the cultivar did not affect the response of potato yield to stem injury. In nine of 14 experiments, potato tolerated high levels of corn borer injury (55-90% of stems injured) without yield loss, suggesting that control of corn borer may not be necessary. Yet, in one of five Superior tests, in two of four Atlantic tests and in two of five Snowden tests, corn borer injury significantly reduced yield. Of the five data sets in which corn borer injury reduced yield, the plateau model fit two data sets and the quadratic model fit one data set. In two of the three cases, these models accounted for nearly identical amounts of total variation in yield as that accounted for by the linear model. The linear model fit four of the five data sets, but the R2 values were low for three of the four tests (0.10, 0.18, and 0.31). The parameter or parameters that interact with corn borer injury to cause tuber yield reduction should be identified before economic injury levels and thresholds are developed.

Animals↗
PubMed2002

Improving Intrinsic Water-Use Efficiency and Crop Yield.

Greater yield per unit rainfall is one of the most important challenges in dryland agriculture. Improving intrinsic water-use efficiency (W(T)), the ratio of CO(2) assimilation rate to transpiration rate at the stomata, may be one means of achieving this goal. Carbon isotope discrimination (Delta(13)C) is recognized as a reliable surrogate for W(T) and there have now been numerous studies which have examined the relationship between crop yield and W(T) (measured as Delta(13)C). These studies have shown the relationship between yield and W(T) to be highly variable. The impact on crop yield of genotypic variation in W(T) will depend on three factors: (i) the impact of variation in W(T) on crop growth rate, (ii) the impact of variation in W(T) on the rate of crop water use, and (iii) how growth and water use interact over the crop's duration to produce grain yield. The relative importance of these three factors will differ depending on the crop species being grown and the nature of the cropping environment. Here we consider these interactions using (i) the results of field trials with bread wheat (Triticum aestivum L.), durum wheat (T. turgidum L.), and barley (Hordeum vulgare L.) that have examined the association between yield and Delta(13)C and (ii) computer simulations with the SIMTAG wheat crop growth model. We present details of progress in breeding to improve W(T) and yield of wheat for Australian environments where crop growth is strongly dependent on subsoil moisture stored from out-of-season rains and assess other opportunities to improve crop yield using W(T).

Journal Article↗
PubMed2001

Genotype x environment interactions in milk yield and quality in Angus, Brahman, and reciprocal-cross cows on different forage systems.

Milk yield and quality were observed on 93 Angus, Brahman, and reciprocal-cross cows over 3 yr to evaluate the interactions of direct and maternal breed effects and heterosis with forage environment. Forage environments were common bermudagrass (BG), endophyte-infected tall fescue (E+), and a rotational system (ROT) of both forages, in which each forage (BG or E+) was grazed during its appropriate season, usually June through October for BG and November through May for E+. Milk yield was estimated each of 6 mo (April through September) via milking machine and converted to a 24-h basis. Milk fat, milk protein, and somatic cell count were analyzed by a commercial laboratory. Heterosis for milk yield was similar among forages, averaging 2.4 kg (P < 0.01). Expressed as percentages of purebred means, heterosis for milk yield was largest on E+ (52.8%), intermediate on ROT (39.3%), and smallest on BG (23.7%). Direct breed effects for milk yield favored Brahman, and they were similar among forages but tended to be larger for E+ (2.5 kg) and ROT (2.8 kg) than for BG (1.3 kg). Direct breed effects for milk fat favored Brahman and were similar among forages but tended to be larger for E+ (1.0%) and ROT (1.0%) than for BG (0.6%). Purebred cows exceeded crossbreds in milk protein by 0.1% on ROT (P < 0.10). Crossbred cows had lower somatic cell counts than purebreds on BG (P < 0.05), E+ (P < 0.01), or ROT (P > 0.30). Heterosis for somatic cell counts as percentages of purebred means was similar for BG (-68.3%) and E+ (-68.9%) and less favorable for ROT (-31.6%). Maternal breed effects for somatic cell count favored Angus on ROT (P < 0.10) with a similar nonsignificant trend on BG and E+. Direct breed effects for somatic cell count favored Brahman on ROT (P < 0.10) with similar nonsignificant trends on BG and E+. These results suggested that a rotation of cows from E+ to BG in the summer can partially alleviate negative effects of E+ on milk yield. Conclusions also indicated an advantage to crossbred cows in somatic cell count and provided evidence of both direct and maternal breed effects for this trait. The results also suggested that direct breed effects for milk yield, milk fat, and somatic cell count and heterosis for milk yield and somatic cell count (as percentages of purebred means) tended to vary with forage environment, indicating a potential for genotype x environment interaction for these traits.

Animal Feed↗
PubMed2005

Relationship of sire expected progeny differences to milk yield in Brangus cows.

Milk yield from 160 Brangus cows sired by 65 Brangus bulls was measured over a 3-yr period with a single-cow milking machine to estimate the relationship of actual milk yield of daughters and their calves' BW with cow sire EPD for milk during the preweaning period. Milk yield was measured six times per year at an average 49, 78, 109, 138, 168, and 198 d postpartum. The regression of daughters' milk yield on sire milk EPD was quadratic (P < 0.01), and the initial linear portion of the curve differed among months (P < 0.05) at an average cow BW. Similarly, the regression of 6-mo average 24-h milk yield on sire milk EPD was curvilinear (P < 0.05). When cow BW was fitted as a covariate in the regression of 6-mo average 24-h milk yield on sire milk EPD, there was an interaction of cow BW with linear sire milk EPD and quadratic sire milk EPD (P < 0.10). The associated response surface suggested that the regression was primarily linear in cows weighing < or = 520 kg and curvilinear in cows weighing >520 kg. A trend existed for the regression of calf 205-d weight on grandsire milk EPD to be curvilinear (P < 0.21); however, the regression of calf 205-d weight on milk yield of their dam was linear (P < 0.01). Results from these data suggest that genetic potential for milk yield, and possibly the associated effects on calf BW transmitted through the grandsire, may have a practical maximum because of nutritional limitations that prevent the expression of genetic potential beyond that level, particularly in heavier cows, which suggests the need to match sire milk EPD and cow BW with production environment.

Animal Feed↗
PubMed1984

Estimating milk yield of sows.

Hourly milk yields were obtained for nine consecutive hours at d 14 of lactation from 92 crossbred (four breed) sows during their first and second lactations. Additionally, milk yields were obtained at d 14 and 20 of lactation from 175 mature Yorkshire X Landrace sows for nine consecutive hours. Each measurement (4,806 observations) was obtained by weighing the pigs before and after each hourly nursing. These data were examined with the objective of understanding the consequences of reducing the number of measurements obtained from each sow. Four data sets were formed from the measurements, namely, first parity crossbred sows, second parity crossbred sows, d 14 and d 20 milk yields from the Yorkshire X Landrace sows. Differences (P less than .01) among the hourly milk yield estimates found in all four data sets were largely accounted for by the low yield for h 1 and moderate reduction for h 2 compared with the means of nine measurements. There were no significant differences among the hourly yields for h 3 through 5 compared with h 3 through 9 in three of the four data sets. Mean hourly milk yield for first parity crossbred sows, however, increased as additional hourly measurements were taken. Using the mean hourly milk yield estimate of h 3 through 5 would give an unbiased estimate of h 3 through 9, except for first parity sows, and a standard error only 13% greater than the standard error for nine hourly measurements. The shorter procedure would save considerable time and labor.

Analysis of Variance↗
PubMed2001

The relationship between milk yield and the incidence of some diseases in dairy cows.

Logistic regression models were used to examine the relationship between milk yield and incidence of certain disorders. Lactations (n = 2197) of 1074 Holstein-Friesian cows from 10 dairies (25 to 146 cows per dairy) in Lower Saxony were studied. The 305-d yield from the previous and current lactations served as the standards for milk yield. Eight disorder complexes were considered: retained placenta, metritis, ovarian cysts, mastitis, claw diseases, milk fever, ketosis, and displaced abomasum. Each disorder complex was modeled separately. In addition to milk yield, the influences of the lactation number, the calving season and the other disorder complexes were examined with the "herd" factor taken into account. A correlation between retained placenta, mastitis, and milk fever to milk yield during the previous lactation was found to be probable and for ketosis and displaced abomasum such a correlation was found to be possible. A connection to the yield in the current lactation was shown for ovarian cysts, claw diseases, and milk fever. No relationship to milk yield existed for metritis. An influence of the lactation number was also demonstrated in various models. Single models allowed a demonstration of the influences of both milk yield and lactation number. Limitations of the model types are discussed.

Animals↗
PubMed2002

Interval and composite interval mapping of somatic cell score, yield, and components of milk in dairy cattle.

Single-marker, interval-mapping (IM) and composite interval mapping (CIM) were used to detect quantitative trait loci (QTL) controlling milk, fat and protein yields, and somatic cell score (SCS). A granddaughter design was used to combine molecular genetic information with predicted transmitting abilities (PTA) and estimated daughter yield deviations (DYD) from eight Dairy Bull DNA Repository Holstein families. Models that included and excluded weights accounting for the uncertainty of the response variable were evaluated in each trait, family and phenotype (DYD and PTA) combination. The genotypic information consisted of 174 microsatellite markers along 29 Bos taurus autosomes. The average number of informative markers per autosome was three and the number of informative sons per family and marker varied between 21 and 173. Within-family results from the least squares single-marker analyses were used in expectation-maximization likelihood IM and CIM implemented with QTL Cartographer. Different CIM model specifications, offering complementary control on the background QTL outside the interval under study, were evaluated. Permutation techniques were used to calculate the genome-wide threshold test statistic values based on 1,000 samples. Results from the DYD and PTA analyses were highly consistent across traits and families. The minor differences in the estimates from the models that accounted for or ignored the uncertainty of the DYD (variance) and PTA (inverse of reliability) may be associated to the elevated and consistent precision of the DYD and PTA among sons. The CIM model best supported by the data had 10 markers controlling for background effects. On autosome (BTA) three, a QTL at 32 cM influencing protein yield was located in family five and a QTL at 74 cM for fat yield was located in family eight. Two map positions associated with SCS were detected on BTA 21, one at 33 cM in family one and the other at 84 cM in family three. A QTL for protein yield was detected between 26 and 36 cM on BTA six, family six, and a QTL for milk yield was detected at 116 cM on BTA seven in family three. The IM and CIM approaches detected a QTL at 3 cM on BTA 14 influencing fat yield in family four. Two map positions on BTA 29 were associated with significant variation of milk (0 cM) and fat yield (14 cM) in family seven. These results suggest the presence of one QTL with pleiotropic effects on multiple traits or multiple QTL within the marker interval. Findings from this study could be used in subsequent fine-mapping work and applied to marker-assisted selection of dairy production and health traits.

Animals↗
PubMed2005

Automatic cluster remover setting affects milk yield and machine-on time in dairy cows.

The primary objectives of this study were to examine effects of automatic cluster remover (ACR) settings on milk yield and machine-on time, and to describe variation in cow body weight (BW) associated with day of bovine somatotropin (bST) cycle. Automatic cluster removal settings of 0.48, 0.6, and 0.8 kg/min were used to regulate the end of milk removal. The setting was changed every 2 wk for 12 wk and followed the sequence 0.8, 0.6, 0.48, 0.48, 0.6, and 0.8 kg/min. Milk yield, machine-on time, and BW were measured for 60 Holstein cows at each milking. Milk yield averaged 19.7, 19.9, and 19.3 kg/cow per milking for ACR settings of 0.48, 0.6, and 0.8, respectively. There was a 2.5% reduction in milk yield at the high setting, but yields were similar for the others. Machine-on time was 6.3, 5.9, and 5.6 min for ACR settings of 0.48, 0.6, and 0.8, respectively. There was an 11.1% reduction in milking time between the 0.8- and 0.48-kg/min settings. The middle ACR setting yielded a shorter milking time than the low setting without reducing production. Milk yield and cow BW increased over the 14-d bST cycle, peaking by d 8, and then declining through d 14. Automated collection of milk yield, milking time, and BW at each milking can be used to establish normal patterns for individual animals, which could be useful in making management decisions.

Animals↗