Accuracy of genomic breeding values for residual feed intake in crossbred beef cattle

The benefit of using genomic breeding values (GEBV) in predicting ADG, DMI, and residual feed intake for an admixed population was investigated. Phenotypic data consisting of individual daily feed intake measurements for 721 beef cattle steers tested over 5 yr was available for analysis. The animals used were an admixed population of spring-born steers, progeny of a cross between 3 sire breeds and a composite dam line. Training and validation data sets were defined by randomly splitting the data into training and testing data sets based on sire family so that there was no overlap of sires in the 2 sets. The random split was replicated to obtain 5 separate data sets. Two methods (BayesB and random regression BLUP) were used to estimate marker effects and to define marker panels and ultimately the GEBV. The accuracy of prediction (the correlation between the phenotypes and GEBV) was compared between SNP panels. Accuracy for all traits was low, ranging from 0.223 to 0.479 for marker panels with 200 SNP, and 0.114 to 0.246 for marker panels with 37,959 SNP, depending on the genomic selection method used. This was less than accuracies observed for polygenic EBV accuracies, which ranged from 0.504 to 0.602. The results obtained from this study demonstrate that the utility of genetic markers for genomic prediction of residual feed intake in beef cattle may be suboptimal. Differences in accuracy were observed between sire breeds when the random regression BLUP method was used, which may imply that the correlations obtained by this method were confounded by the ability of the selected SNP to trace breed differences. This may also suggest that prediction equations derived from such an admixed population may be useful only in populations of similar composition. Given the sample size used in this study, there is a need for increased feed intake testing if substantially greater accuracies are to be achieved.     

Age of dam and sex of calf adjustments and genetic parameters for gestation length in Charolais cattle

To estimate adjustment factors and genetic parameters for gestation length (GES), AI and calving date records (n = 40,356) were extracted from the Canadian Charolais Association field database. The average time from AI to calving date was 285.2 d (SD = 4.49 d) and ranged from 274 to 296 d. Fixed effects were sex of calf, age of dam (2, 3, 4, 5 to 10, > or = 11 yr), and gestation contemporary group (year of birth x herd of origin). Variance components were estimated using REML and 4 animal models (n = 84,332) containing from 0 to 3 random maternal effects. Model 1 (M1) contained only direct genetic effects. Model 2 (M2) was G1 plus maternal genetic effects with the direct x maternal genetic covariance constrained to zero, and model 3 (M3) was G2 without the covariance constraint. Model 4 (M4) extended G3 to include a random maternal permanent environmental effect. Direct heritability estimates were high and similar among all models (0.61 to 0.64), and maternal heritability estimates were low, ranging from 0.01 (M2) to 0.09 (M3). Likelihood ratio tests and parameter estimates suggested that M4 was the most appropriate (P < 0.05) model. With M4, phenotypic variance (18.35 d2) was partitioned into direct and maternal genetic, and maternal permanent environmental components (hd2 = 0.64 +/- 0.04, hm2 = 0.07 +/- 0.01, r(d,m) = -0.37 +/- 0.06, and c2 = 0.03 +/- 0.01, respectively). Linear contrasts were used to estimate that bull calves gestated 1.26 d longer (P < 0.02) than heifers, and adjustments to a mature equivalent (5 to 10 yr old) age of dam were 1.49 (P < 0.01), 0.56 (P < 0.01), 0.33 (P < 0.01), and -0.24 (P < 0.14) d for GES records of calves born to 2-, 3-, 4-, and > or = 11-yr-old cows, respectively. Bivariate animal models were used to estimate genetic parameters for GES with birth and adjusted 205-d weaning weights, and postweaning gain. Direct GES was positively correlated with direct birth weight (BWT; 0.34 +/- 0.04) but negatively correlated with maternal BWT (-0.20 +/- 0.07). Maternal GES had a low, negative genetic correlation with direct BWT (-0.15 +/- 0.05) but a high and positive genetic correlation with maternal BWT (0.62 +/- 0.07). Generally, GES had near-zero genetic correlations with direct and maternal weaning weights. Results suggest that important genetic associations exist for GES with BWT, but genetic correlations with weaning weight and postweaning gain were less important.     

注射用头孢呋辛钠的安全性试验研究

通过试验研究对注射用头孢呋辛钠的安全性进行评价。采用豚鼠和家兔分别进行本品的全身用药过敏性、血管和肌肉局部刺激性及家兔红细胞体外溶血性试验研究。结果显示本品对豚鼠无明显全身过敏性、静脉注射对家兔耳缘静脉无明显局部刺激性、对家兔肌肉注射给药无明显局部刺激性、对家兔红细胞无明显体外溶血性。表明本品的各项安全性均良好,为实际应用提供了有力依据。     

Evolution of mechanisms controlling mating behavior

The proximate mechanisms underlying mating behavior in naturally occurring species can be fundamentally different from those in more commonly studied laboratory and domesticated forms. In naturally occurring species, reproductive strategies are much more diverse, and mechanisms controlling behavior are correspondingly diverse. A variety of hormonal, environmental, and social cues can be used to activate mating behavior. Which cues are used by particular species depends on differences in environmental and physiological constraints imposed by particular reproductive strategies. Study of this diversity of mechanisms promises to identify specific selective forces that have shaped their evolution. This evolutionary perspective leads to widely applicable generalizations and provides a useful context within which to conceptualize differences between species, populations, and individuals.     

Impacts of rising atmospheric carbon dioxide on model terrestrial ecosystems

In model terrestrial ecosystems maintained for three plant generations at elevated concentrations of atmospheric carbon dioxide, increases in photosynthetically fixed carbon were allocated below ground, raising concentrations of dissolved organic carbon in soil. These effects were then transmitted up the decomposer food chain. Soil microbial biomass was unaffected, but the composition of soil fungal species changed, with increases in rates of cellulose decomposition. There were also changes in the abundance and species composition of Collembola, fungal-feeding arthropods. These results have implications for long-term feedback processes in soil ecosystems that are subject to rising global atmospheric carbon dioxide concentrations.     

Regionalization: a strategy that will assist with bovine tuberculosis control and facilitate trade

It is expected that the revised chapter on bovine tuberculosis in the Terrestrial Animal Health Code of the Office Internationale des Epizooties (OIE) will embrace regionalization as a functional means of assisting countries, states or regions to meet the requirements for freedom from tuberculosis and to facilitate trade. The benefits and applications of regionalization, which comprises zoning and compartmentalisation, are discussed. Regionalization requires that a country's veterinary administration is able to implement transparent and auditable biosecurity measures that will ensure that the tuberculosis-free status of a subpopulation of cattle is maintained despite the presence of infection in another cattle subpopulation, or in other domestic or wild animal species. Zoning, which requires cattle subpopulations to be separated by geographic boundaries, provides a practical basis whereby countries, states or regions, can progress towards freedom from tuberculosis, regardless of the source of infection for defined cattle subpopulations. Compartmentalisation however, requires that husbandry or management practices will be used to prevent a tuberculosis-free cattle subpopulation from contacting interspecific and intraspecific sources of infection. This will be difficult to achieve except for specialised cases such as artificial breeding centers.     

Test duration for growth, feed intake, and feed efficiency in beef cattle using the GrowSafe System

This study was conducted to determine the optimum test duration and the effect of missing data on accuracy of measuring feed efficiency and its 4 related traits ADG, DMI, feed conversion ratio, and residual feed intake in beef cattle using data from 456 steers with 5,397 weekly averaged feed intakes and BW repeated measurements taken over 91 d. Data were collected using the GrowSafe System at the University of Alberta Kinsella Research Station. The changes and relative changes in phenotypic residual variances and correlations (Pearson and Spearman) among data from shortened test durations (7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, or 84 d) and a 91-d test were used to determine the optimum test duration for the 4 traits. The traits were fitted to a mixed model with repeated measures using SAS. Test durations for ADG, DMI, feed conversion ratio, and residual feed intake could be shortened to 63, 35, 42, and 63 d, respectively, without significantly reducing the accuracy of the tests when BW was measured weekly. The accuracy of the test was not compromised when up to 30% of the records were randomly removed after the first 35 d on test. These results have valuable and practical implications for performance and feed efficiency testing in beef cattle.     

Serum concentrations across time after subcutaneous administration of liposome-encapsulated or standard oxymorphone in Rhesus macaques

Our lab has developed a slow‐release liposomal formulation of oxymorphone (LEOx). The purpose of this study was to compare serum concentrations of oxymorphone after administration of LEOx and standard oxymorphone (STDOx) to healthy female rhesus macaques. At baseline, 1 mL of blood was drawn from the femoral vein with the animal in a restraint cage. Primates were divided into two groups: (i) LEOx 1.0 mg kg^–1(n = 4); 2) STDOx 0.1 mg kg^–1(n = 4). Unloaded liposomal vehicle (0.5 mL) was used as a control (n = 2). All treatments were given subcutaneously in a shaved area proximal to the right ileal wing. Femoral venous blood was drawn and serum concentrations of drug were measured at 0.5, 1, 2, 4, 8, 12, 24, 48, 72, 96, and 120 hours. Serum concentrations were measured with ELISA. Serum concentrations were compared between groups and within groups across time with anova . Drug was not detected at any time point in the control group. While sedation was not objectively measured, no animal appeared overly sedate after either treatment. All animals willingly accepted treats and did not appear nauseated or somnolent. Serum concentrations of drug were not significantly different between the two treatment groups from 0 to 2 hours. From 4 hours through 72 hours, however, serum concentrations were significantly higher (p < 0.05) in the animals that received LEOx. By 12 hours, serum concentrations of drug fell below the limit of detection (1.5 ng mL^–1) in animals that received STOx. In animals that received LEOx, serum concentrations at 72 hours were comparable to those measured at 4 hours in animals that received STOx. These results suggest that subcutaneous administration of liposomal oxymorphone yields extended serum levels of drug. These results also suggest that liposomal oxymorphone may provide therapeutic (i.e. analgesic) serum concentrations of drug for 2–3 days after a single subcutaneous administration. Further studies are warranted to assess analgesic efficacy and pharmacokinetics of lipsomal oxymorphone in primates.