Patterns of milking unit kick-off as a proxy for habituation to milking in primiparous cows.

The onset of lactation and the subsequent habituation to the milking routine is a stressful period, particularly for primiparous (PRI) cows. The objective of this study was to describe the dynamics of milking unit kick-off (KO) behavior in PRI cows during the first 3 mo of lactation, considering multiparous (MUL) cows as a reference for comparison. In addition, the potential associations between KO and milk yield and mastitis presentation were investigated. A total of 869 cows (PRI = 199; MUL = 670) on a dairy farm in northern CO were included in the analysis. Cows calving between August and November 2020 were enrolled from 3 DIM until 90 DIM. Participants were milked 3×/day in a 60-unit rotary parlor and data from each milking session were downloaded from parlor management software. Milking unit kick-off was used as a proxy for habituation to the milking procedure. Kick-off events were reported by the milking system and defined as an abrupt interruption in the milk flow during the milking process. Cow KO events were recorded for each milking session. Subsequently, occurrence of KO was analyzed by grouping the 3 consecutive milking sessions in each day and categorized as yes or no, indicating whether or not an individual kicked at least once in a given day. Data were analyzed by repeated measures ANOVA and logistic regression, including parity category, calving season, occurrence of dystocia, and their potential interactions in the models. Least squares means for daily proportions of KO were calculated considering the number of cows with KO events per day in the PRI and MUL categories. Subsequently, odds ratios for the occurrence of KO in PRI versus MUL were calculated at multiple periods of time. When KO was analyzed by DIM, proportions of KO were greater in PRI than in MUL during the whole monitoring period. In PRI, proportions of KO increased from 0.10/d to 0.20/d between 3 DIM and 15 DIM, to start decreasing around 30 DIM and remaining above MUL up to 90 DIM. On the contrary, in MUL cows, proportions of KO remained close to 0.05/d during the 90-d period. Overall, the odds of KO were greater for PRI versus MUL cows (odds ratio [95% confidence interval] = 2.07 [1.58-2.73]). No differences in milk yield were established among KO categories, while the percentage of cows affected with mastitis was greater in cows grouped in the quartile with more frequent KO events. We concluded that the relationship between days in milk and the proportion of PRI cows displaying KO was not linear, but rather KO increased during the first 2 wk postpartum before decreasing after the first month of lactation. First-parity cows had greater levels of KO than MUL cows, which is most likely associated with the process of habituation to milking during their first lactation.

The Functional Field of View of Older Adults is Associated With Contrast Discrimination in the Magnocellular not Parvocellular Pathway.

OBJECTIVES: As we age, the functional field of view (FFOV) declines and these declines predict falls and motor vehicle accidents in older adults (Owsley, C. (2013). Visual processing speed. Vision Research, 90, 52-56. doi:10.1016/j.visres.2012.11.014). To increase understanding of possible causes of this decline, the current study explored whether the FFOV in older adults is associated with the sensitivity of the magnocellular and parvocellular sub-cortical pathways. METHOD: Forty-four younger (M = 27.18, SD = 5.40 years) and 44 older (M = 72.18, SD = 5.82 years) adults completed an FFOV test and the steady- and pulsed-pedestal paradigms of Pokorny and Smith (Pokorny, J., & Smith, V. C. (1997). Psychophysical signatures associated with magnocellular and parvocellular pathway contrast gain. Journal of the Optical Society of America. A, Optics, Image Science, and Vision, 14, 2477-2486. doi:10.1364/josaa.14.002477) as measures of magnocellular and parvocellular pathways, respectively. RESULTS: Older adults made more FFOV errors and had higher contrast discrimination thresholds in both the steady- and pulsed-pedestal paradigms, than younger adults. FFOV errors in the younger group were not related to contrast discrimination thresholds. In multiple regression, older group FFOV errors showed a strong unique association with contrast discrimination thresholds mediated via the magnocellular, but not the parvocellular pathway. DISCUSSION: We infer that reduced magnocellular pathway contrast sensitivity may contribute to reduced functional vision in older adults.

Consensus recommendations on calf- and herd-level passive immunity in dairy calves in the United States.

Passive immunity in calves is evaluated or quantified by measuring serum or plasma IgG or serum total protein within the first 7 d of age. While these measurements inform about circulating concentrations of this important protein, they are also a proxy for evaluating all of the additional benefits of colostral ingestion. The current individual calf standard for categorizing dairy calves with successful passive transfer or failure of passive transfer of immunity are based on serum IgG concentrations of ≥10 and <10 g/L, respectively. This cutoff was based on higher mortality rates in calves with serum IgG <10 g/L. Mortality rates have decreased since 1991, but the percentage of calves with morbidity events has not changed over the same time period. Almost 90% of calves sampled in the USDA National Animal Health Monitoring System's Dairy 2014 study had successful passive immunity based on the dichotomous standard. Based on these observations, a group of calf experts were assembled to evaluate current data and determine if changes to the passive immunity standards were necessary to reduce morbidity and possibly mortality. In addition to the USDA National Animal Health Monitoring System's Dairy 2014 study, other peer-reviewed publications and personal experience were used to identify and evaluate potential standards. Four options were evaluated based on the observed statistical differences between categories. The proposed standard includes 4 serum IgG categories: excellent, good, fair, and poor with serum IgG levels of ≥25.0, 18.0-24.9, 10.0-17.9, and <10 g/L, respectively. At the herd level, we propose an achievable standard of >40, 30, 20, and <10% of calves in the excellent, good, fair, and poor categories, respectively. Because serum IgG concentrations are not practical for on-farm implementation, we provide corresponding serum total protein and %Brix values for use on farm. With one-third of heifer calves in 2014 already meeting the goal of ≥25 g/L serum IgG at 24 h of life, this achievable standard will require more refinement of colostrum management programs on many dairy farms. Implementation of the proposed standard should further reduce the risk of both mortality and morbidity in preweaned dairy calves, improving overall calf health and welfare.

Improving Outcome Accountability of Block Grants: Lessons Learned From the Preventive Health and Health Services Block Grant Evaluation.

The flexibility federal block grants provide recipients poses challenges for evaluation. These challenges include aggregating data on wide-ranging activities grant recipients implement and the outcomes they achieve. In 2014, we began designing an evaluation to address the challenges of assessing outcomes and to improve outcome accountability for the Preventive Health and Health Services Block Grant. Through the use of evaluability assessment methodology, review of existing data and the literature, and key informant interviews, we developed a measurement framework to assess outcomes resulting from recipients' ability to use grant funds to meet their locally prioritized needs. We argue our evaluation approach demonstrates that block grants, and other similarly flexible programs, can be evaluated through appropriately designed measures. Our efforts challenge the idea that flexibility presents an insurmountable barrier to evaluation and outcome accountability for federal block grants.

The effect of retirement on elderly cognitive functioning.

Cognitive functioning exhibits a clear lifecycle pattern with a general deterioration over older ages. This article estimates the short-term effect of retirement on cognitive performance of elderly Australians by exploiting the exogenous variation in retirement decisions induced by changes in social security eligibility rules. The empirical results show that on average retirement has a negative but modest effect on cognition, and the rate of cognitive decline with age is greater for men than women. The results for women display no significant effects on working memory and speed of information processing. The article further adds to the literature by providing evidence on the possible mechanisms through which retirement could affect individual's cognitive performance. We find that moving into retirement leads women to increase the time spent in mental and household activities, which may in part explain the modest effect we observe for women.

Proposed dairy calf birth certificate data and death loss categorization scheme.

The majority of dairy heifer calves in the United States are destined to be dairy replacements. However, many dairy heifer and bull calves die before 6 mo of age. Of these calves, about 6% (more than 500,000 calves) die at birth or shortly after (i.e., currently termed "stillbirth"). An additional 6% of dairy heifers die during the preweaning period. Death loss in dairy calves is primarily due to stillbirths, failure to adapt to extrauterine life, and infectious disease processes. The reasons for preweaning heifer calf deaths caused by infectious diseases are generally categorized based on easily recognizable clinical signs such as digestive disease/scours or respiratory disease. Most causes of calf death can be mitigated by appropriate preventive care or well-tailored treatments, meaning that the typical death loss percentage could be decreased with better management. Producers could gather information on the circumstances near birth and at death if they had appropriate guidance on what details to record and monitor. This paper provides recommendations on data to collect at the time of birth (i.e., calf birth certificate data). The recording of these critical pieces of information is valuable in evaluating trends over time in morbidity and mortality events in dairy calves. Ideally, necropsy examination would substantially improve the identification of cause of death, but even without necropsy, attribution of cause of death can be improved by more carefully defining death loss categories in on-farm record systems. We propose a death loss categorization scheme that more clearly delineates causes of death. Recommendations are provided for additional data to be collected at the time of death. Recording and analyzing birth certificate and death loss data will allow producers and veterinarians to better evaluate associations between calf risk factors and death, with the goal of reducing dairy calf mortality.

Preweaned heifer management on US dairy operations: Part II. Factors associated with colostrum quality and passive transfer status of dairy heifer calves.

Passive transfer of immunity is essential for the short- and long-term health of dairy calves. The objective of this study was to evaluate factors associated with colostrum quality and passive transfer status of US heifer calves. This study included 104 operations in 13 states that participated in the calf component of the National Animal Health Monitoring System's Dairy 2014 study. This 18-mo longitudinal study included 1,972 Holstein heifer calves from birth to weaning. Multivariable mixed linear regression models were selected using backward elimination model selection after univariate screening to determine which factors were associated with colostrum IgG and serum IgG concentrations. The mean colostrum IgG concentration was 74.4 g/L with 77.4% of colostrum samples having IgG concentrations >50 g/L. The final model for colostrum IgG included colostrum source and a categorized temperature-humidity index value (cTHI) for the month before calving. Mean colostrum IgG concentrations were highest for dams in third and higher lactations (84.7 g/L) and lowest for commercial colostrum replacers (40.3 g/L). Colostrum IgG concentrations were highest for cTHI ≥70 (72.6 g/L) and lowest for cTHI <40 (64.2 g/L). The mean serum IgG concentration was 21.6 g/L, with 73.3% of calves having serum IgG concentrations >15 g/L. The final model for serum IgG concentration included region, heat treatment of colostrum, colostrum source, timing to first feeding, volume of colostrum fed in the first 24 h, age of the calf at blood sampling, and colostrum IgG concentration. Mean serum IgG concentrations were highest for calves that received colostrum from first-lactation dams (25.7 g/L) and lowest for calves fed commercial colostrum replacer (16.6 g/L). Serum IgG concentrations were higher for calves fed heat-treated colostrum (24.4 g/L) than for calves fed untreated colostrum (20.5 g/L). Serum IgG concentration was positively associated with the volume of colostrum fed in the first 24 h and colostrum IgG concentration, and negatively associated with the number of hours from birth to colostrum feeding and age (days) at blood collection. Dairy producers should be encouraged to measure the quality of colostrum before administering it to calves and to measure serum IgG or a proxy such as serum total protein or Brix to evaluate passive immunity and colostrum management programs.

Preweaned heifer management on US dairy operations: Part I. Descriptive characteristics of preweaned heifer raising practices.

The objective of this study was to describe preweaned dairy heifer calf management practices on dairy operations across the United States that were used to analyze factors associated with colostrum quality and passive transfer, Cryptosporidium and Giardia, morbidity and mortality, and average daily gain. This study included 104 dairy operations in 13 states that participated in the National Animal Health Monitoring System's Dairy 2014 calf component study. This 18-mo longitudinal study focused on dairy heifer calves from birth to weaning, and data were collected on 2,545 heifer calves. Descriptive statistics were generated regarding colostrum feeding, preweaning housing, milk feeding and consumption, growth, morbidity and mortality, and weaning practices. The majority of calves enrolled were Holsteins (89.4%). Over half the calves (63.2%) enrolled in the study received the majority of their colostrum via bottle; however, 22.1% of calves from 51.0% of operations received colostrum via suckling from their dams. For all calves, the mean time to the first colostrum feeding was 2.8 h, and the average amount of colostrum at the first feeding was 2.9 L, with 4.5 L provided in the first 24 h. The mean serum IgG of all calves was 21.7 g/L; however, 76.0% of operations had at least 1 calf with failure of passive transfer of immunity with a serum IgG below 10 g/L. The majority of calves in the study were housed individually (86.6%). Nonetheless, 20.2% of operations housed some calves in groups, representing 13.4% of all calves. Approximately one-half of the calves in the study (52.3%) were dehorned or disbudded during the preweaning period, with only 27.8% of these calves receiving analgesics or anesthetics during the procedure. Whole or waste milk was the liquid diet type fed to 40.1% of calves, and milk replacer was fed to 34.8% of calves. A combination of milk and milk replacer was fed to 25.1% of calves. Calves, on average, were fed 2.6 L per feeding and fed 2.6 times/d, resulting in a total of 5.6 L of liquid diet fed per day. The mean average daily gain for all calves enrolled in the study was 0.7 kg/d. Fecal samples were collected and almost all operations had at least 1 calf positive for Cryptosporidium (94.2%) or Giardia (99.0%), and 84.6% of operations had calves that tested positive for both Cryptosporidium and Giardia. Over one-third of calves (38.1%) had at least one morbidity event during the preweaning period and the mortality rate was 5.0%. The mean age at weaning was 65.7 d. This study provides an update on dairy heifer raising practices in the United States.

Preweaned heifer management on US dairy operations: Part V. Factors associated with morbidity and mortality in preweaned dairy heifer calves.

The objective of this study was to evaluate morbidity and mortality in preweaned dairy heifer calves based on different health, feeding, and management practices, as well as environmental factors. This study was conducted as part of the calf component of the National Animal Health Monitoring System's Dairy 2014 study, which included 104 dairy operations in 13 states. The calf component was an 18-mo longitudinal study focused on dairy heifer calves from birth to weaning; data were collected on 2,545 calves. The percentage morbidity for all calves enrolled in the study was 33.9%. Backward elimination model selection was used after univariate screening to determine which management practices and environmental factors significantly affected morbidity and mortality. The final morbidity model included birth weight, serum IgG concentration, ventilation type, and average temperature-humidity index (THI) during the preweaning period. After controlling for other independent variables in the model, calves born at a higher birth weight had a lower predicted risk of morbidity than calves with a lower birth weight. An increase in serum IgG concentration was associated with decreased morbidity. Calves housed in positive- or cross-ventilated systems had a 2.2 times higher odds of developing disease compared with calves housed in natural ventilation systems. Average THI during the preweaning period was inversely correlated with morbidity; as THI increased, the predicted morbidity risk decreased. The percent mortality for all calves enrolled in the study was 5.0%. The final mortality model included birth weight, serum IgG concentration, amount of fat/day in the liquid diet, and morbidity. After controlling for other independent variables in the model, calves born at a higher birth weight had a lower risk of mortality. An increase in serum IgG concentration decreased the risk of mortality. The odds of mortality were 3.1 times higher in calves fed ≤0.15 kg of fat/d in the liquid diet compared with calves fed ≥0.22 kg of fat/d. The odds of mortality were 4.7 times higher in calves that experienced any disease throughout the preweaning period than in calves with no disease. In summary, morbidity and mortality were both associated with birth weight and serum IgG concentration. Additionally, morbidity was associated with ventilation type and average monthly THI, and mortality was associated with amount of fat per day in the liquid diet and morbidity.

Preweaned heifer management on US dairy operations: Part VI. Factors associated with average daily gain in preweaned dairy heifer calves.

The study objective was to evaluate average daily gain (ADG) in dairy heifer calves based on health, feeding, management practices, and environmental factors. This study included 102 operations in 13 states that participated in the calf component of the National Animal Health Monitoring System's Dairy 2014 study. This 18-mo longitudinal study included 1,410 Holstein heifer calves monitored from birth to weaning. The mean ADG from birth to final weight was 0.74 kg/d. Backward elimination model selection in Proc Mixed after univariate screening determined factors that significantly affected ADG. The final model included dam lactation number, singleton versus twin birth, bedding type, Giardia and Cryptosporidium fecal shedding, disease events, a categorized average temperature-humidity index for the preweaning period (pTHI), amount of protein in the liquid diet (kg/d), milk pasteurization, direct-fed microbials, and the interaction between milk pasteurization and direct-fed microbials. After controlling for other independent variables in the model, calves born to first-lactation dams gained less (0.60 kg/d) than calves from second- (0.65 kg/d) or third- or greater-lactation (0.64 kg/d) dams. Singleton calves gained 0.07 kg/d more than twins. Calves bedded with sand or no bedding gained less (0.49 kg/d) than calves on all other bedding types. Calves negative for Cryptosporidium or Giardia at the time of sampling gained 0.03 or 0.02 kg/d more, respectively, than calves that were positive for Cryptosporidium or Giardia. Calves with no disease events gained 0.07 kg/d more than calves with one or more disease events. Calves experiencing an average pTHI <50 gained more (0.67 kg/d) than calves experiencing an average pTHI from 50 to 69 (0.62 kg/d), or ≥70 (0.59 kg/d). Within the range of observed kilograms of protein fed per day in the liquid diet, every additional 0.1 kg of protein fed per day equated to 0.02 kg/d of gain. Calves fed milk replacer with a direct-fed microbial gained less (0.44 kg/d) than calves fed milk replacer without a direct-fed microbial (0.60 kg/d) and calves fed pasteurized or unpasteurized milk regardless of direct-fed microbial use. These results highlight the importance of feeding a quantity and quality of a liquid diet to achieve optimal growth, keeping calves free of disease, the type or status of bedding, and mitigating the effects of temperature and humidity on preweaning ADG.

Perceptual processing deficits underlying reduced FFOV efficiency in older adults.

Older adults are known to perform more poorly on measures of the functional field of view (FFOV) than younger adults. Specific contributions by poor bottom-up and or top-down control of visual attention to the reduced FFOV of older adults were investigated. Error rates of older and younger adults were compared on a FFOV task in which a central identification task, peripheral localization task, and peripheral distractors were presented in high and low contrast. Older adults made more errors in all conditions. The effect of age was independent of the contrast of the peripheral target or distractors. The performance cost of including the central task was measured and found to be negligible for younger adults. For older adults performance costs were present in all conditions, greater with distractors than without, and greater for a low rather than high contrast central stimulus when the peripheral target was high contrast. These results are consistent with older adults compensating for reduced sensory input or bottom-up capture of attention by relying more heavily on top-down control for which they are resource limited.

The Impact of Older Age and Sex on Motion Discrimination.

Background/Study Context: Reports of age-related differences on motion discrimination tasks have produced inconsistent findings concerning the influence of sex. Some studies have reported that older women have higher thresholds than older men, with others finding that women have higher motion thresholds regardless of age group. Reports of the age at which declines in motion discrimination first occur also differ, with some studies reporting declines only in groups aged over 70 years, with others reporting that age-related decline occurs at a younger age. The current study aimed to determine whether the sex differences found occur because relative to men, women have greater difficulty extracting motion signals from noise (Experiment 1) or have greater difficulty making use of the available motion cues (Experiment 2) in these complex moving stimuli. In addition, the influence of these manipulations on groups aged under and over 70 years was explored. METHODS: Motion discrimination measures were obtained using 39 older adults aged between 60 and 85 years (21 women) and 40 younger adults aged between 20 and 45 years (20 women). In Experiment 1, coherent motion and relative motion displacement thresholds were obtained. In Experiment 2, coherent motion thresholds were obtained for stimuli containing either 150 or 600 dots. RESULTS: In Experiment 1, the older group had significantly higher thresholds on the relative motion displacement and coherent motion tasks than a younger group. No differences in motion sensitivity were found in the older groups aged under or over 70 years. Women regardless of age group had significantly higher thresholds than men on both tasks. In Experiment 2, the older group had higher coherence thresholds than the younger group, and the number of dots presented had no influence on thresholds, for the older group or older women specifically. In the younger group, women had higher coherence thresholds than men with presentation of 150 but not 600 dots. There were 51% of the older group who showed evidence of age-related decline on all the motion coherence tasks conducted, with half of these in each the group aged under and over 70 years. CONCLUSION: Difficulties with noise exclusion failed to explain the sex differences found. The increased number of motion cues present when a larger number of dots were included was sufficient to reduce coherence thresholds in younger women but not older men or women. In addition to age, developmental history and sex may provide further predictors in older individuals of decline on measures of motion discrimination.

Static and dynamic components of right ventricular afterload are negatively associated with calf survival at high altitude.

The purposes of this study were to evaluate mean, systolic, and diastolic pulmonary arterial pressures; pulmonary arterial pulse pressures; and systemic oxygen extraction fraction as risk factors for the survival of suckling calves on one ranch located at an altitude of ≥ 2,730 m in Colorado, USA. A prospective cohort study of 58 calves was performed. Pulmonary arterial pressures and systemic oxygen extraction were measured when calves were approximately 3 mo (86 ± 7 d) and 7 mo (197 ± 6 d) of age. Seven of the 58 calves (12%), 4 steers and 3 heifers, were unaccounted for and presumed dead between 3 and 7 mo of age. Calves presumed to have died between 3 and 7 mo of age had significantly greater mean ( = 0.005) and systolic ( = 0.001) pulmonary arterial pressures and greater pulse pressures ( = 0.03) at 3 mo of age than calves that survived to 7 mo. Calves presumed to have died tended to have greater systemic oxygen extraction fractions at 3 mo of age than calves that survived ( = 0.13). Diastolic pressure was not associated with survival ( = 0.27). Mean pulmonary arterial pressure is predominantly determined by static resistance attributable to distal pulmonary arterial remodeling. Pulse pressure and systolic pulmonary arterial pressure represents the dynamic or oscillatory resistance and is determined by the characteristics of ventricular ejection and proximal arterial stiffness. These findings indicate that it may be beneficial to include pressure measurements indicative of both static and dynamic pulmonary arterial resistance in the selection of breeding stock at high altitude.

Angus calves born and raised at high altitude adapt to hypobaric hypoxia by increasing alveolar ventilation rate but not hematocrit.

The objective of this study was to evaluate the effect of altitude on arterial blood-gases and hematocrit in Angus-based calves. It was hypothesized that alveolar ventilation rate, as indicated by arterial pCO, would increase with altitude but hematocrit would not. Five Angus-based herds ( = 30 to 80 per cohort) located at 105 m, 1,470 m, 2,010 m, 2,170 m, and 2,730 m above sea level were enrolled in this prospective cohort study. A portable analyzer measured blood-gas tensions in coccygeal arterial blood. Calves at 1,470 m, 2,170 m, and 2,730 m were sampled twice, at approximately 4 mo and 7 mo of age. Calves at 105 m and 2,010 m were sampled once, at 7 or 4 mo of age, respectively. Linear regression analyses were used to determine the fixed effect of herd (a proxy for altitude) on the 4 outcome variables pCO, pO, pH, and hematocrit, while controlling for age and sex. As hypothesized, alveolar ventilation rate increased with altitude ( < 0.001). Hematocrit, however, did not show a clear association with altitude except for an increase from 105 m to ≥ 1,470 m ( < 0.001). Arterial pO decreased significantly with increasing altitude in calves at 4 mo and 7 mo of age ( < 0.001). The adjusted mean values of the 4 variables studied were similar at 4 and 7 mo of age for all of the herds studied. This indicates that suckling calves show minimal respiratory or erythrocytic adaptation to hypoxemia and hypocapnia with increasing age, regardless of altitude. We propose that the lack of an erythrocytic response in hypoxemic calves born and raised at high altitude prevents a deleterious increase in viscous resistance and, consequently, pulmonary arterial pressure. This physiological response, or lack thereof, may be a survival adaptation in a species predisposed to hypoxia-induced pulmonary hypertension.

The altitude at which a calf is born and raised influences the rate at which mean pulmonary arterial pressure increases with age.

Right heart failure secondary to pulmonary hypertension is a leading cause of mortality among suckling beef calves in the Rocky Mountain region. The objective of this study was to track changes in pulmonary arterial pressures (PAP) in healthy calves born and raised at altitudes ranging from 1,470 to 2,730 m. It was hypothesized that calves located at higher altitudes would show a greater increase in mean PAP (mPAP) with age than would be experienced by calves located at lower altitudes. The rationale is that high altitude hypobaric hypoxia causes a greater rate of vascular remodeling and, consequently, greater resistance to blood flow than calves located at lower altitudes. A prospective study was conducted on 5 cohorts of suckling calves from 4 herds located at altitudes of 1,470, 2,010, 2,170, and 2,730 m. In total, 470 PAP measurements were obtained from 258 calves. As hypothesized, calves located at altitudes ≥2,170 m showed a significant increase in mPAP with age ( ≤ 0.002) whereas calves at 1,470 m did not ( = 0.16). Except for calves at 2,170 m ( < 0.001), systolic PAP did not increase with age ( ≥ 0.16). Diastolic PAP increased with age at altitudes ≥ 2,170 m ( ≤ 0.09) but did not change in calves at 1,470 m ( = 0.20). In summary, mPAP and the rate at which mPAP increases with age are positively associated with the altitude at which calves are born and raised.

Mean pulmonary arterial pressures in Angus steers increase from cow-calf to feedlot-finishing phases.

Pulmonary arterial hypertension due to hypoxia-induced pulmonary vascular remodeling is the predominant cause of right-sided congestive heart failure (CHF) in cattle. Historically, heart failure was problematic only at altitudes over 2,134 m. However, anecdotal reports suggest that the incidence of heart failure is increasing in feedlot cattle at moderate altitude (800 to 1,600 m), with late-fed, or fat, cattle at greatest risk. The goal of this study was to evaluate pulmonary arterial pressures (PAP) in a cohort of male Angus calves from suckling to finishing to better understand why heart failure is particularly problematic in fat cattle. It was hypothesized that mean PAP would increase through the feeding period and that the calves with the greatest pressures at high altitude would have the greatest pressures as fat cattle. A total of 362 PAP measurements were obtained from 153 calves. Calves were tested at altitudes of 2,170 (4 and 6 mo old), 1,560 (13 mo old), and 1,300 m (13 and 18 mo old). Mean PAP were greater in 18-mo-old steers than any other age group (mean = 50.3 mm Hg; 95% confidence interval 48.2 to 52.4; < 0.05). Calves that had the greatest mean pressure at 6 mo of age tended to have the greatest mean pressures at 18 mo of age ( = 0.45, < 0.001). The increase in mean PAP with increasing age and adiposity likely predisposed the steers to an increased risk of CHF during the finishing phase.

Herd factors associated with dairy cow mortality.

Summary studies of dairy cow removal indicate increasing levels of mortality over the past several decades. This poses a serious problem for the US dairy industry. The objective of this project was to evaluate associations between facilities, herd management practices, disease occurrence and death rates on US dairy operations through an analysis of the National Animal Health Monitoring System's Dairy 2007 survey. The survey included farms in 17 states that represented 79.5% of US dairy operations and 82.5% of the US dairy cow population. During the first phase of the study operations were randomly selected from a sampling list maintained by the National Agricultural Statistics Service. Only farms that participated in phase I and had 30 or more dairy cows were eligible to participate in phase II. In total, 459 farms had complete data for all selected variables and were included in this analysis. Univariable associations between dairy cow mortality and 162 a priori identified operation-level management practices or characteristics were evaluated. Sixty of the 162 management factors explored in the univariate analysis met initial screening criteria and were further evaluated in a multivariable model exploring more complex relationships. The final weighted, negative binomial regression model included six variables. Based on the incidence rate ratio, this model predicted 32.0% less mortality for operations that vaccinated heifers for at least one of the following: bovine viral diarrhea, infectious bovine rhinotracheitis, parainfluenza 3, bovine respiratory syncytial virus, Haemophilus somnus, leptospirosis, Salmonella, Escherichia coli or clostridia. The final multivariable model also predicted a 27.0% increase in mortality for operations from which a bulk tank milk sample tested ELISA positive for bovine leukosis virus. Additionally, an 18.0% higher mortality was predicted for operations that used necropsies to determine the cause of death for some proportion of dead dairy cows. The final model also predicted that increased proportions of dairy cows with clinical mastitis and infertility problems were associated with increased mortality. Finally, an increase in mortality was predicted to be associated with an increase in the proportion of lame or injured permanently removed dairy cows. In general terms, this model identified that mortality was associated with reproductive problems, non-infectious postpartum disease, infectious disease and infectious disease prevention, and information derived from postmortem evaluations. Ultimately, addressing excessive mortality levels requires a concerted effort that recognizes and appropriately manages the numerous and diverse underlying risks.

Do older individuals have difficulty processing motion or excluding noise? Implications for safe driving.

This study aimed to determine if difficulties extracting signal from noise explained poorer coherent motion thresholds in older individuals, particularly women. In four experimental conditions the contrast of the signal and noise dots used in a random dot kinematogram was manipulated. Coherence thresholds were highest when the signal dots were of a lower contrast than the noise dots and lowest when the signal dots were of a higher contrast than the noise dots. In all conditions the older group had higher coherence thresholds than the younger group, and women had higher thresholds than men. Significant correlations were found between coherence thresholds and self-reported driving difficulties in conditions in which the signal dots had to be extracted from noise only. The results indicate that older individuals have difficulties extracting signal from noise in cluttered visual environments. The implications for safe driving are discussed.

Technical note: A comparison of DNA collection methods in cattle and yaks.

A variety of biological materials are suitable for the analysis of bovine DNA. The objective of this study was to evaluate the ease of collection, storage, and cost as well as quality and quantity of DNA samples obtained from Bos taurus (European cattle) and Bos grunniens (yak) using 2 different sample types: whole blood sampling and nasal swabs. Hair follicle DNA samples from yaks were also analyzed. Deoxyribonucleic acid samples were collected from 1 herd of Black Angus yearling bulls (n = 166) and 1 herd of yaks (n = 24). A NanoDrop Bioanalyzer ND1000 was used to quantify DNA. To assess DNA purity, absorbance ratios were determined at wavelengths of 260 nm relative to 280 nm and 260 nm relative to 230 nm. Single nucleotide polymorphism genotyping was performed using a competitive allele-specific PCR (KASP) genotyping system and the call rates to 3 specific SNP were compared. Using a commercially available nonautomated ethanol DNA extraction technique, nasal swabs yielded a greater quantity of DNA than blood (P < 0.0001) and a greater quality DNA sample than blood (P < 0.0001). Blood and nasal swab performance in SNP genotyping assays were similar (P = 0.5). The greater expense of nasal swabs was offset by their ease of use: less time, skill, and equipment was needed to obtain a sample and the storage of samples was more convenient (room temperature). In yaks, accessing the coccygeal vein, which is relatively straightforward in cattle, was difficult. Nasal swabbing and hair follicle sampling in yaks was performed relatively easily. Yak hair follicles were a poor source of DNA. In conclusion, DNA collection using nasal swabs was more convenient and provided a greater quantity of DNA and better quality sample than blood collection in both Angus and yak. Notably, yak hair was a poor source of DNA, and yak blood was difficult to obtain.

The influence of contrast on coherent motion processing in dyslexia.

The aim of the experiments was to investigate how manipulating the contrast of the signal and noise dots in a random dot kinematogram (RDK), influenced on motion coherence thresholds in adults with dyslexia. In the first of two experiments, coherent motion thresholds were measured when the contrasts of the signal and noise dots in an RDK were manipulated. A significantly greater processing benefit was found for the group with dyslexia than a control group when the signal dots were of higher contrast than the noise dots. However, a significant processing disadvantage was found for the group with dyslexia relative to the control group when the signal dots were of lower contrast than the noise dots. These findings were interpreted as supporting evidence for the noise exclusion hypothesis of dyslexia. In Experiment 2, the effect on coherent motion thresholds of presenting a cue that alerted observers to which stimuli, high or low contrast contained the signals dots was investigated. When the cue directed attention to low contrast signal dots presented in high contrast noise, coherent motion thresholds were only enhanced for the group with dyslexia. This manipulation produced equivalent coherent motion thresholds in the reader groups. In other conditions, the group with dyslexia had significantly higher coherent motion thresholds than the control group. It was concluded that adults with dyslexia who show evidence of a coherent motion deficit (37% of the dyslexia group in each experiment), have a specific difficulty in noise exclusion. This appears to occur as consequence of a sensory processing deficit in the magnocellular or dorsal stream.