The Intestinal Tumour Microenvironment

The tumour microenvironment (TME) of intestinal tumours is highly complex and comprises a network of stromal cells, tumour cells, immune cells and fibroblasts, as well as microorganisms. The tumour location, environmental factors and the tumour cells themselves influence the cells within the TME. Immune cells can destroy tumour cells and are associated with better patient prognosis and response to therapy; however, immune cells are highly plastic and easily influenced to instead promote tumour growth. The interaction between local immune cells and the microbiome can lead to progression or regression of intestinal tumours. In this chapter, we will discuss how tumour development and progression can influence, and be influenced by, the microenvironment surrounding it, focusing on immune and fibroblastic cells, and the intestinal microbiota, particularly in the context of colorectal cancer.

Estimation of genetic parameters for traits associated with reproduction, lactation, and efficiency in sows

Increased milk production due to high litter size, coupled with low feed intake, results in excessive mobilization of sow body reserves during lactation, which can have detrimental effects on future reproductive performance. A possibility to prevent this is to improve sow lactation performance genetically, along with other traits of interest. The aim of this study was to estimate breed-specific genetic parameters (by parity, between parities, and across parities) for traits associated with lactation and reproduction in Yorkshire and Landrace sows. Performance data were available for 2,107 sows with 1 to 3 parities (3,424 farrowings total). Sow back fat, loin depth and BW at farrowing, sow feed intake (SFI), and body weight loss (BWL) during lactation showed moderate heritabilities (0.21 to 0.37) in both breeds, whereas back fat loss (BFL), loin depth loss (LDL), and litter weight gain (LWG) showed low heritabilities (0.12 to 0.18). Among the efficiency traits, sow lactation efficiency showed extremely low heritability (near zero) in Yorkshire sows but a slightly higher (0.05) estimate in Landrace sows, whereas sow residual feed intake (SRFI) and energy balance traits showed moderate heritabilities in both breeds. Genetic correlations indicated that SFI during lactation had strong negative genetic correlations with body resource mobilization traits (BWL, BFL, and LDL; -0.35 to -0.70), and tissue mobilization traits in turn had strong positive genetic correlations with LWG (+0.24 to +0.54; < 0.05). However, SFI did not have a significant genetic correlation with LWG. These genetic correlations suggest that SFI during lactation is predominantly used for reducing sow body tissue losses, rather than for milk production. Estimates of genetic correlations for the same trait measured in parities 1 and 2 ranged from 0.64 to 0.98, which suggests that first and later parities should be treated as genetically different for some traits. Genetic correlations estimated between traits in parities 1 and 2 indicated that BWF and BWL measured in parity 1 can be used as indicator traits for SFI and SRFI measured in parities 1 and 2. In conclusion, traits associated with lactation in sows have a sizable genetic component and show potential for genetic improvement.

Genetic parameter estimation and evaluation of Duroc boars for feed efficiency and component traits

MacNeil, M. D. and Kemp, R. A. 2015. Genetic parameter estimation and evaluation of Duroc boars for feed efficiency and component traits. Can. J. Anim. Sci. 95: 155–159. The objective of this research was to produce a genetic evaluation for traits related to feed efficiency of Duroc boars. Meeting this objective required partitioning phenotypic (co)variance into additive genetic and environmental components for feed intake and traits indicative of growth and body composition. Boars (N=3291) were housed in group pens of 22 to 24 animals with two electronic feeders per pen and feed intake was recorded for 8 to 14 wk. Body weight was recorded for each boar at the start and end of test, at approximately 100 kg and at up to three times during the test. The pedigree used contained sire and dam of each boar with at least one recorded phenotype (N=4651) and their maternal and paternal grandsires. Variance components were estimated by restricted maximum likelihood for animal models in a series of uni-variate and bi-variate analyses. Two multiple trait genetic evaluations were conducted to predict estimated breeding value for feed intake using animal models. The first evaluation included feed intake (h2=0.33±0.05), age at 100 kg (h2=0.31±0.04), and subcutaneous fat depth (h2=0.47±0.05). The second genetic evaluation included feed intake, average daily gain (h2=0.27±0.04), mid-test weight (h2=0.33±0.05), and subcutaneous fat depth. Genetic correlations of feed intake with age at 100 kg and fat depth were –0.80±0.05 and 0.57±0.08, respectively. Estimated breeding values for measures of feed efficiency (residual feed intake and residual gain) were calculated from the results of the second analysis and the associated additive genetic (co)variance components.

Genetic analysis of reproductive traits and antibody response in a PRRS outbreak herd

Porcine reproductive and respiratory syndrome (PRRS) is the most economically significant disease impacting pig production in North America, Europe, and Asia, causing reproductive losses such as increased rates of stillbirth and mummified piglets. The objective of this study was to explore the genetic basis of host response to the PRRS virus (PRRSV) in a commercial multiplier sow herd before and after a PRRS outbreak, using antibody response and reproductive traits. Reproductive data comprising number born alive (NBA), number alive at 24 h (NA24), number stillborn (NSB), number born mummified (NBM), proportion born dead (PBD), number born dead (NBD), number weaned (NW), and number of mortalities through weaning (MW) of 5,227 litters from 1,967 purebred Landrace sows were used along with a pedigree comprising 2,995 pigs. The PRRS outbreak date was estimated from rolling averages of farrowing traits and was used to split the data into a pre-PRRS phase and a PRRS phase. All 641 sows in the herd during the outbreak were blood sampled 46 d after the estimated outbreak date and were tested for anti-PRRSV IgG using ELISA (sample-to-positive [S/P] ratio). Genetic parameters of traits were estimated separately for the pre-PRRS and PRRS phase data sets. Sows were genotyped using the PorcineSNP60 BeadChip, and genome-wide association studies (GWAS) were performed using method Bayes B. Heritability estimates for reproductive traits ranged from 0.01 (NBM) to 0.12 (NSB) and from 0.01 (MW) to 0.12 (NBD) for the pre-PRRS and PRRS phases, respectively. S/P ratio had heritability (0.45) and strong genetic correlations with most traits, ranging from -0.72 (NBM) to 0.73 (NBA). In the pre-PRRS phase, regions associated with NSB and PBD explained 1.6% and 3% of the genetic variance, respectively. In the PRRS phase, regions associated with NBD, NSB, and S/P ratio explained 0.8%, 11%, and 50.6% of the genetic variance, respectively. For S/P ratio, 2 regions on SSC 7 (SSC7) separated by 100 Mb explained 40% of the genetic variation, including a region encompassing the major histocompatibility complex, which explained 25% of the genetic variance. These results indicate a significant genomic component associated with PRRSV antibody response and NSB in this data set. Also, the high heritability and genetic correlation estimates for S/P ratio during the PRRS phase suggest that S/P ratio could be used as an indicator of the impact of PRRS on reproductive traits.

Genetic parameters among growth and carcass traits of Canadian Charolais cattle

Genetic parameters for three growth and five carcass traits were estimated for Charolais using a combination of carcass progeny test, purebred field performance and pedigree data. Heritabilities and genetic and residual correlations were derived from variance components for birth weight (BWT, n = 54 221), 205-d weaning weight (WT205, n = 31 384), postweaning gain (PWG, n = 19 403), hot carcass weight (HCW, n = 6958), average subcutaneous fat thickness (FAT, n = 6866), longissimus muscle area (REA, n = 6863), marbling score (MAR, n = 6903) and estimated carcass lean yield percentage (PLY, n = 6852) with an animal model (n = 78 728) and restricted maximum likelihood. Breed of dam and contemporary group appropriate to each trait were included as fixed effects in the model, whereas random effects included direct genetic for all traits, maternal genetic for BWT and WT205, and maternal permanent environmental for WT205. Carcass traits were adjusted to a constant harvest age of 425 d. Heritability estimates of 0.53, 0.22, and 0.21 were obtained for direct components of BWT, WT205, and PWG, respectively, and maternal heritabilities were 0.16 and 0.10 for BWT and WT205, respectively. Direct × maternal genetic correlations for BWT (-0.49) and WT205 (-0.35) were negative. Heritabilities for HCW, FAT, REA, MAR, and PLY were 0.33, 0.39, 0.43, 0.34, and 0.46, respectively. Genetic correlations among direct effects for growth traits were moderately positive and generally uncorrelated with maternal effects across traits. Lean and fat deposition in the carcass generally had negative, unfavorable genetic correlations, although improvement in lean yield and marbling score may not be strongly antagonistic. Genetic correlations of direct and maternal components of growth traits with carcass traits suggested that selection for increased growth rate would not be antagonistic to improvement in carcass yield or meat quality. Key words: Carcass, Charolais, correlation, genetic parameters, growth

Weaning, yearling, and preharvest ultrasound measures of fat and muscle area in steers, bulls, and heifers

Longissimus muscle area and fat thickness were measured following weaning, at yearling, and prior to harvest using real-time ultrasound, and corresponding carcass measurements were recorded 3 to 7 d following the preharvest scan in composite steers (n = 116, 447 +/- 19 d), bulls (n = 224, 521 +/- 11 d), and heifers (n = 257,532 +/- 12 d). Although fat deposition was limited in bulls and heifers from weaning to yearling, coefficients of variation ranged from 8.46 to 13.46% for muscle area, and from 27.55 to 38.95% for fat thickness, indicating that significant phenotypic variance exists across genders. Residual correlations, adjusted for the effects of year of birth, gender, and age at measurement, were high and ranged from 0.79 to 0.87 among ultrasound and carcass measures of muscle area. Residual correlations among ultrasound and carcass measures of fat thickness were also high, ranging from 0.64 to 0.86. Weaning and/or yearling ultrasound muscle area yielded similarly accurate predictions of carcass muscle area. Yearling ultrasound fat thickness accounted for 13% more of the observed variance in carcass fat thickness than the weaning ultrasound measure in single-trait prediction models. When both weaning and yearling ultrasound measures were used to predict carcass fat thickness, partial R2 values were 0.15 and 0.61 for weaning and yearling ultrasound fat thickness, respectively. The difference between predicted and carcass measures with respect to muscle area (fat thickness) was less than 6.45 cm2 (2.5 mm) for 80.2 to 88.9% (90.3 to 95%) of animals. Preharvest ultrasound measures yielded standard errors of prediction of less than 4.95 cm2 for muscle area and 1.51 mm or less for fat thickness. These results indicate that ultrasound measures taken between weaning and yearling provide accurate predictors of corresponding carcass traits in steers, bulls, and heifers.

Genetic evaluation of carcass yield using ultrasound measures on young replacement beef cattle

Live weight and ultrasound measures of fat thickness and longissimus muscle area were available on 404 yearling bulls and 514 heifers, and carcass measures of weight, longissimus muscle area, and fat thickness were available on 235 steers. Breeding values were initially estimated for carcass weight, longissimus muscle area, and fat thickness using only steer carcass data. Breeding values were also estimated for weight and ultrasound muscle area and fat thickness using live animal data from bulls and heifers, with traits considered sex-specific. The combination of live animal and carcass data were also used to estimate breeding values in a full animal model. Breeding values from the carcass model were less accurate and distributed more closely around zero than those from the live data model, which could at least partially be explained by differences in relative amounts of data and in phenotypic mean and heritability. Adding live animal data to evaluation models increased the average accuracy of carcass trait breeding values 91, 75, and 51% for carcass weight, longissimus muscle area, and fat thickness, respectively. Rank correlations between breeding values estimated with carcass vs live animal data were low to moderate, ranging from 0.16 to 0.43. Significant rank changes were noted when breeding values for similar traits were estimated exclusively with live animal vs carcass data. Carcass trait breeding values estimated with both live animal and carcass data were most accurate, and rank correlations reflected the relative contribution of carcass data and their live animal indicators. The addition of live animal data to genetic evaluation of carcass traits resulted in the most significant carcass trait breeding value accuracy increases for young replacements that had not yet produced progeny with carcass data.

Genetic parameters for ultrasound and carcass measures of yield and quality among replacement and slaughter beef cattle

Real time ultrasound (RTU) measures of longissimus muscle area and fat depth were taken at 12 and 14 mo of age on composite bulls (n = 404) and heifers (n = 514). Carcass longissimus muscle area and fat depth, hot carcass weight, estimated percentage lean yield, marbling score, Warner-Bratzler shear force, and 7-rib dissectable seam fat and lean percentages were measured on steers (n = 235). Additive genetic variances for longissimus muscle area were 76 and 77% larger in bulls at 12 and 14 mo than the corresponding estimates for heifers. Heritability estimates for longissimus muscle area were 0.61 and 0.52 in bulls and 0.49 and 0.47 in heifers at 12 and 14 mo, respectively. The genetic correlations of longissimus muscle area of bulls vs heifers were 0.61 and 0.84 at 12 and 14 mo, respectively. Genetic correlations of longissimus muscle area measured in steer carcasses were 0.71 and 0.67 with the longissimus muscle areas in bulls and heifers at 12 mo and 0.73 and 0.79 at 14 mo. Heritability estimates for fat depth were 0.50 and 0.35 in bulls and 0.44 and 0.49 in heifers at 12 and 14 mo, respectively. The genetic correlation of fat depth in bulls vs heifers at 12 mo was 0.65 and was 0.49 at 14 mo. Genetic correlations of fat depth measured in bulls at 12 and 14 mo with fat depth measured in steers at slaughter were 0.23 and 0.21, and the corresponding correlations of between heifers and steers were 0.66 and 0.86, respectively. Live weights at 12 and 14 mo were genetically equivalent (r(g) = 0.98). Genetic correlations between live weights of bulls and heifers with hot carcass weight of the steers were also high (r(g) > 0.80). Longissimus muscle area measured using RTU was positively correlated with carcass measures of longissimus muscle area, estimated percentage lean yield, and percentage lean in a 7-rib section from steers. Measures of backfat obtained using RTU were positively correlated with fat depth and dissectable seam fat from the 7-rib section of steer carcasses. Genetic correlations between measures of backfat obtained using RTU and marbling were negative but low. These results indicate that longissimus muscle area and backfat may be under sufficiently different genetic control in bulls vs heifers to warrant being treated as separate traits in genetic evaluation models. Further, traits measured using RTU in potential replacement bulls and heifers at 12 and 14 mo of age may be considered different from the corresponding carcass traits of steers.

Tumor-specific Tc1, but not Tc2, cells deliver protective antitumor immunity

We investigated whether secretion of multiple cytokines by CD8+ T cells is associated with improved protection against tumor challenge. We show that antitumor immunity induced by immunization with dendritic cells and a MHC class I-binding tumor peptide are dependent on secretion of IFN-gamma but not IL-4 or IL-5 by host cells. To further address the role of IL-4 and IL-5 in antitumor immunity, tumor-specific TCR-transgenic CD8+ T cells were activated in vitro to generate cytotoxic T (Tc) 1 cells that secrete high IFN-gamma and no IL-4 or IL-5 or Tc2 cells that secrete IL-4, IL-5, and some IFN-gamma. Both cell types killed target cells in vitro. Tc1 and Tc2 cells were adoptively transferred into syngeneic hosts, and their ability to protect against tumor challenge was compared. Tc1 cells were able to significantly delay tumor growth, whereas Tc2 cells or Tc2 cells from IFN-gamma(-/-) donors had no effect. This was due to neither the inability of Tc2 cells to survive in vivo or to migrate to the tumor site nor their inability to secrete IL-4 and/or IL-5 in the presence of limiting amounts of anti-CD3. However, IFN-gamma secretion by Tc2 cells was triggered inefficiently by restimulation with Ag compared with anti-CD3. We conclude that the ability to secrete "type 2" cytokines, and cytotoxic ability, have a limited role in antitumor immune responses mediated by CD8+ T cells, whereas the capacity to secrete high amounts of IFN-gamma remains the most critical antitumor effector mechanism in vivo.

Gene microarrays reveal extensive differential gene expression in both CD4(+) and CD8(+) type 1 and type 2 T cells

An important subdivision of effector T cells can be made based on patterns of cytokine production and functional programs. Type 1 T cells produce IFN-gamma and protect against viral pathogens, whereas type 2 cells produce cytokines such as IL-4 and IL-5 and protect against large extracellular parasites. Both CD4(+) and CD8(+) T cells can be polarized into type 1 or type 2 cytokine-secreting cells, suggesting that both populations play a regulatory role in immune responses. In this study, we used high-density oligonucleotide arrays to produce a comprehensive picture of gene expression in murine CD4(+) Th1 and Th2 cells, as well as CD8(+) type 1 and type 2 T cells. Polarized type 1 and 2 cells transcribed mRNA for an unexpectedly large number of genes, most of which were expressed in a similar fashion between type 1 and type 2 cells. However, >100 differentially expressed genes were identified for both the CD4(+) and CD8(+) type 1 and 2 subsets, many of which have not been associated with T cell polarization. These genes included cytokines, transcription factors, molecules involved in cell migration, as well as genes with unknown function. The program for type 1 or type 2 polarization was similar for CD4(+) and CD8(+) cells, since gene expression patterns were roughly the same. The expression of select genes was confirmed using real-time PCR. The identification of genes associated with T cell polarization may give important insights into functional and phenotypic differences between effector T cell subsets and their role in normal responses and inflammatory disease.

Effects of rooting and tree growth of selected woodland species on cap integrity in a mineral capped landfill site

The above and below ground growth of three tree species (Alnus glutinosa, Pinus nigra var. maritima and Acer pseudoplatanus) was studied on a containment landfill site at Waterford, Hertfordshire, UK. Tree root architecture was studied using soil inspection pits excavated next to 12 trees of each species and mapped in detail. Tree height was related to soil thickness over the compacted mineral cap. No roots entered the cap where soil thickness was 1.3 m, but a few roots, especially of alder, were observed within it when the soil cover was 1.0 m or less. Micromorphological analysis of undisturbed samples of the mineral cap suggested that roots exploited weaknesses in the cap rather than actively causing penetration into it. Alder roots were more tolerant of anaerobic conditions within the cap than the other species examined. The results confirm that mineral caps should be covered by 1.5 m of soil or soil-forming material if tree establishment is intended over a restored landfill site, unless protected by other parts of a composite capping system.

Dendritic cell elimination as an assay of cytotoxic T lymphocyte activity in vivo

We show in this paper that the survival of antigen-loaded dendritic cells in vivo may be used as a sensitive readout of CTL activity. We have previously shown that dendritic cells labeled with the fluorescent dye CFSE and injected sub-cutaneously into mice migrate spontaneously to the draining lymph node where they persist for several days. In the presence of effector CTL responses, dendritic cells loaded with specific antigen rapidly disappear from the draining lymph node. In this paper we extend the above observations and set up a simple and sensitive method to reveal CTL activity in individual mice in vivo. Dendritic cells were labeled with two different fluorochromes, loaded with antigen or left untreated, and mixed together before injection into mice. We show that only the dendritic cells loaded with specific antigen were cleared from the draining lymph node, while dendritic cells not loaded with antigen remained unaffected. Cytotoxic responses generated by immunization with peptide-loaded dendritic cells, or by infection with influenza virus, could be revealed using this method. Comparison of the differential survival of dendritic cells populations mixed together also allowed us to accurately evaluate the disappearance of dendritic cells, irrespective of variability in the injection site and other parameters. Given the ability of dendritic cells to efficiently take up and present complex antigens, nucleic acids and apoptotic bodies, this method may also allow the evaluation of cytotoxic activity against antigens that are not characterized in terms of peptide epitopes.

Electronic identification: Applications in beef production and research

Individual identification of beef cattle is not new to the Canadian beef industry, as traceback systems played a pivotal role in the eradication of bovine tuberculosis in the 1940s and 1950s and brucellosis in the 1970s and 1980s. Recent concerns over animal health (e.g., bovine spongiform encephaolopathy), export markets, product consistency, meat quality (e.g., tenderness, marbling) and safety (e.g., Escherichia. coli 0157:H7, Salmonella spp.) make reestablishment of a traceback system a logical approach to assuring consumer confidence in Canadian beef. Originally, simple Kurl-lockTM ear tags with a unique number were used to trace individuals back to their herd of origin. Although useful for addressing disease concerns, this system did not lend itself to compiling additional information (e.g., growth performance, animal health, breeding programs, carcass quality) for use in management or marketing decisions. More sophisticated electronic identification systems can readily interface with computers and make information management an even more pivotal component of beef production. Several electronic identification systems (e.g., bar codes, radio frequency identification, read–write systems) are being assessed for their effectiveness for identifying individual cattle under production conditions. In research applications, this technology has the potential for individual animals to become the experimental unit under group housing conditions. By combining electronic identification technology with devices that measure physiological (e.g., temperature, pH, body weight, feed intake) parameters, researchers will be able to collect data in natural production environments that were previously only obtainable under controlled experimental conditions with a limited number of animals. Key words: Electronic identification, beef, traceback, radio frequency identification

A study on the variation of feed efficiency in station tested beef bulls

The records of 282 young beef bulls from eight breeds tested from November 1981 to April 1987 at the Ellerslie Bull Test Station, Alberta, Canada, were used to study the variation in feed efficiency among young performance-tested bulls. Considerable variation existed among the animals in both residual metabolizable energy consumption and residual dry matter consumption. The heritability estimates for residual metabolizable energy consumption and residual dry matter consumption were 0.33 and 0.29, respectively. In addition, residual metabolizable energy consumption and residual dry matter consumption were moderately correlated (r = 0.43) with conventional feed-to-gain ratio, indicating that conventional feed-to-gain ratio only accounted for 18% of the variation in residual metabolizable energy consumption or residual dry matter consumption. It was, therefore, worthwhile to use residual metabolizable energy consumption or residual dry matter consumption as separate measures of feed efficiency. For rapid improvement in feed efficiency in beef cattle, selection pressure should be applied to both growth traits and residual energy consumption or residual dry matter consumption. Multi-trait optimum restricted selection indices and similar selection procedures may serve as useful means in balanced selection programs to improve the productivity of beef cattle. Key words: Feed efficiency, residual ME consumption, beef bulls

Selection for cow lifetime pregnancy rate using bull and heifer growth and reproductive traits in composite cattle

Genetic correlations of lifetime pregnancy rate with bull and heifer growth and reproductive traits in a beef composite population were estimated. Yearling scrotal circumference had an unfavorable genetic correlation (rg = −0.25) while yearling tonometer score was favorably related (rg = 0.22) to lifetime pregnancy rate. Heifer pregnancy rate, birth weight, weaning weight, yearling weight and age at puberty in heifers had significant genetic correlations (rg = 0.97, 0.58, 0.57, 0.33 and −0.21, respectively) with lifetime pregnancy rate. Lifetime pregnancy rate may be successfully predicted by easy-to-measure heifer growth traits. Using indices including scrotal and heifer growth traits, annual genetic change in lifetime pregnancy rate may be increased 3.1 times compared with direct selection. Key words: Scrotal circumference, tonometer, pregnancy, reproduction, puberty

Genetic trends for weaning weight during development of a multibreed population of beef cattle in two contrasting environments

Genetic trends for weaning weight were determined in two herds of multibreed beef cattle that originated from a common base and were subject to mutual breeding policies in separate environments. The herds diverged for the direct though not the maternal genetic component of weaning weight within the 13-yr period examined; in the final year, the difference (P < 0.001) between the herds was almost 3 kg. This could have been partly due to unequal selection differentials and generation intervals. Results suggested the extent of natural selection also differed between the two environments. Key words: Beef cattle, crossbreeding, genetic trends, selection, weaning weight

Machine effects on accuracy of ultrasonic prediction of backfat and ribeye area in beef bulls, steers and heifers

Pre-slaughter ultrasound and carcass measurements of ribeye area (REA) and backfat (FAT) were recorded on composite beef bulls (n = 60), heifers (n = 60) and steers (n = 60). Breed composition of the composite was: 0.44 British (Hereford, Angus and Shorthorn) 0.25 Charolais, 0.25 Simmental and 0.06 Limousin. The Aloka SSD-1100 (AL) and the Tokyo Keiki CS 3000 (TK) ultrasound machines were compared by evaluating the difference between ultrasound and carcass measurements (bias), and the standard error of prediction (SEP). AL under-predicted REA in all three sexes while TK overpredicted heifers and steers and underpredicted bulls. Both machines were similar in accuracy among bulls for REA. For FAT AL underpredicted all three sexes while TK underpredicted heifers and had very small bias for bulls and steers. SEP for FAT were similar for both machines. Both machines underpredicted REA in larger muscled cattle and overpredicted in smaller-muscled cattle. Both machines also underpredicted FAT in fatter animals and overpredicted FAT in leaner animals. Machines were similar in accuracy among cattle with larger REA but differed significantly (P < 0.05) among smaller-muscled cattle. Machines were comparable in accuracy among animals of all FAT sizes. This study demonstrates that there is an important relationship between machine and the size and depth of muscle and backfat, respectively, and consequently between machine and sex, in accuracy of ultrasound prediction. Key words: Beef cattle, ultrasound, accuracy, back fat, ribeye area

Comparison of models for genetic evaluation of scrotal circumference in crossbred bulls

The aim of this study was to evaluate the effect of including concomitant body weight and(or) a random dam effect in genetic evaluation models on variance component estimates and standard error of prediction for scrotal circumference (SC) at 6, 8, 10, and 12 mo. Variance components and average standard errors of prediction were compared under models differing in either the number of related traits (M11 [SC], M12 [SC and BW]) or an uncorrelated random dam effect (M21 [SC], M22 [SC and BW]) using records on 1,547 bull calves. In a single-trait model (M11), estimates of direct heritabilities (h2a) for SC were .45, .49, .57, and .66 at 6, 8, 10, and 12 mo, respectively. In a two-trait model (M12), h2a were similar to those in M11 model. In M21, h2a for SC were .37, .42, .54, and .65, whereas the proportions of phenotypic variance due to dams (d2) were .12, .11, .04, and .02 at 6, 8, 10, and 12 mo, respectively. Similarly, in M22, h2a for SC were .36, .44, .56, and .65 and d2 were .13, .10, .02, and .02. Standard errors of prediction for SC EBV from M22 were reduced by 2.86, 1.21, 3.02, and 1.99% relative to M21 and by 6.45, 2.70, 2.72, and 1.21% relative to M11 at 6, 8, 10, and 12 mo, respectively. Standard errors of prediction for SC EBV from M12 were reduced by .06, .73, 1.56, and .87% relative to M11 at 6, 8, 10, and 12 mo, respectively. The importance of the dam effect decreased with age for both SC and BW. These results demonstrate that a two-trait (SC and BW) animal model would result in more accurate evaluations of yearling SC EBV in beef cattle than a single-trait model.

Estimates of direct and maternal genetic parameters for weight traits and backfat thickness in a multibreed population of beef cattle

Variance components were estimated for weight at birth, weaning, and 365 d of age, and yearling ultrasonic backfat thickness in a multibreed population of beef cattle. Data (n = 5880) were available on F1 animals and various crosses leading up to, and including, a composite breed (7/16 British, 1/4 Charolais, 1/4 Simmental, and 1/16 Limousin). Single- and two-trait analyses were conducted using an animal model and derivative-free REML procedures. Covariates representing fractional contributions of each of the four purebred groups and average heterotic effects, both direct and maternal, accounted for breed composition. Direct and maternal genetic, maternal permanent environmental, and residual effects were the random variables. Only minor differences existed between parameter estimates obtained from the various analyses. Mean direct heritabilities were 0.51, 0.33, 0.48, and 0.37 for weight at birth, weaning, and 365-d, and backfat, respectively, which, though well within the range of published estimates, seemed higher than average, indicating diversity in the founding purebreds. Mean maternal heritabilites were 0.09, 0.13, and 0.08 for the three consecutive weights. A likelihood ratio test showed maternal heritability and(or) the direct-maternal correlation was important (P < 0.001) for 365-d weight. Averaged across weights, the direct-maternal correlation was 0.07, lacking evidence of genetic antagonism. No age of dam or random maternal effects on backfat were apparent. Phenotypic correlations between weight at birth and weaning and weight at weaning and 365-d were 0.46 and 0.76, respectively. Though moderate between birth and weaning weight, maternal genetic and permanent environmental correlations between weaning and 365-d weight approached unity, demonstrating maternal carryover effects. Phenotypic and genetic correlations of 0.19 and –0.13, respectively, implied a limited association between 365-d weight and backfat, which possibly would have been stronger had fat been measured later in life. Estimates of variance components suitable for general use can be obtained from data from multibreed animals by considering breed and heterotic effects. Key words: Beef cattle, crossbreds, genetic parameters, heritability, maternal effects

Contributions of preweaning growth information and maternal effects for prediction of carcass trait breeding values among crossbred beef cattle

Preweaning and carcass trait records from crossbred steers (n = 1015) and heifers (n = 957) were used to estimate genetic parameters and to investigate the efficacy of maternal effects and preweaning growth information for improving estimation of EBV for carcass traits for crossbred beef cattle. Dams (n = 775) representing three F1 and twelve back-cross combinations involving the Charolais, Hereford, Angus, Simmental and Shorthorn breeds were mated over six years to Limousin bulls (n = 36) at two locations in western Canada. Four animal models, involving from zero to three maternal (co)variances were used to analyze four carcass traits. Rank and simple correlations indicated that maternal effects were relatively unimportant for estimation of direct carcass trait breeding values. Direct heritabilities were 0.28, 0.12 and 0.16 for birth weight, preweaning daily gain and weaning weight, and were 0.20, 0.35, 0.50 and 0.38 for hot carcass weight, fat thickness, ribeye area and percent lean yield, respectively. Maternal heritabilities were 0.21, 0.22 and 0.40 for birth weight, preweaning daily gain and weaning weight, respectively. Estimated genetic correlations between percent lean yield and hot carcass weight, fat thickness and ribeye area were –0.05, –0.85 and 0.39, respectively, and 0.30 between hot carcass weight and ribeye area. Direct genetic effects for birth weight had moderate (0.51 to 0.54) correlations with direct effects for carcass weight, ribeye area and percent lean yield. Direct genetic effects for fat thickness were negatively correlated with direct effects for birth weight (−0.44), preweaning daily gain (−0.15) and weaning weight (−0.25). Maternal genetic effects for preweaning traits had near-zero correlations with direct genetic effects for fat thickness and percent lean yield. Adding preweaning growth information to genetic evaluations for carcass traits slightly decreased prediction error variances for breeding values and would be recommended when information on carcass traits is limited. Key words: Genetic evaluation, carcass traits, beef cattle

Effects of breed and dietary energy content within breed on growth performance, carcass and chemical composition and beef quality in Hereford and Simmental steers

Forty-eight Hereford and 60 Simmental steers were used to evaluate breed differences as affected by dietary energy content on growth performance, carcass and chemical composition, and beef quality. Diets were based on corn silage, alfalfa haylage, whole corn, and SBM and were formulated to provide 2.52 to 2.81 Mcal kg−1 ME and 11.7 to 12.6% protein in the growing phase and 2.69 to 2.86 Mcal kg−1 ME and 9.7 to 10.4% protein in the finishing phase. Low- and high-ener-gy diets were formulated for each breed with the high-energy diet for Hereford serving as the low-energy diet for Simmental. Steers were slaughtered after attaining 8 to 10 mm backfat determined by ultrasound. Higher energy diets increased (P < 0.09) average daily gain (ADG) and feed efficiency within both breeds. Hereford gained more rapidly (P = 0.074) and were more (P = 0.001) efficient in converting feed to gain than Simmental. High-energy diets decreased (P = 0.001) days on feed for both breeds and increased (P = 0.001) carcass weights for Simmental. Otherwise, carcass and chemical composition were generally unaffected by dietary energy content. Simmental were heavier (P = 0.001) and leaner (P = 0.001) than Hereford while marbling classification and intramuscular fat content were similar (P > 0.10) between breeds. While shear force decreased (P = 0.043) feeding the low-energy diet to Simmental, other shear and palatability attributes were unaffected by dietary energy content or breed. Altering dietary energy content for Hereford and Simmental influenced growth performance without affecting carcass and chemical composition and beef quality. Key words: Hereford, Simmental, marbling, shear, palatability, growth performance, carcass

Survival of Listeria monocytogenes in sea water and effect of exposure on thermal resistance

Survival, recoverability and sublethal injury of two strains of Listeria monocytogenes, Scott A and an environmental strain KM, on exposure to sea water at 12.8 or 20.8 degrees C was determined using in situ diffusion chambers. Plate counts were used to assess recoverability and injury while 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) reduction was used to determine respiratory activity. T90 values (times for 10-fold decreases in numbers of recoverable cells) on non-selective medium (trypticase soya agar with 0.6% yeast extract) at 12.8 and 20.8 degrees C were 61.7 and 69.2 h for L. monocytogenes Scott A, and 103.0 and 67.0 h for L. monocytogenes KM, respectively. On selective medium (Oxford agar), T90 values at 12.8 and 20.8 degrees C were 60.6 and 56.9 h for L. monocytogenes Scott A, and 83.0 and 65.9 h for L. monocytogenes KM, respectively. With Scott A, the percentage of sublethally injured cells at 12.8 and 20.8 degrees C was 1.7 and 17.7%, respectively, while for KM the values were 19.0 and 1.6%, respectively. The fraction of cells reducing CTC but which were not recoverable on plating progressively increased on exposure to sea water. Listeria monocytogenes KM challenged at 58 degrees C showed an apparent increase in heat resistance after exposure to sea water at 20.8 degrees C for 7 d (D58 = 2.64 min) compared with before exposure (D58 = 1.24). This increase in thermal resistance was not apparent at temperatures greater than 63 degrees C, and analysis of the best-fit regression lines fitted to the thermal data obtained from the two cell populations indicated that their thermal resistance was not significantly different (P > 0.05) over the temperature range tested (58-62 degrees C).

Thermal death times of Hafnia alvei cells in a model suspension and in artificially contaminated hot-smoked kahawai (Arripis trutta)

In New Zealand the product most frequently implicated in cases of scombroid poisoning is hot-smoked kahawai (Arripis trutta). Using a Hafnia alvei strain, previously isolated from a portion of hot-smoked kahawai with a histamine level of 1,659.4 mg/kg, thermal death trials were carried out in a model suspension (0.1% peptone) at 54, 55, 56, 57, and 58 degrees C. From the linear regression line (R2 = 0.98) fitted to observed D values plotted against temperature, calculated D values for 54, 55, 56, 57, and 58 degrees C were estimated to be 0.63, 0.36, 0.20, 0.11, and 0.06 min, respectively, giving a z value of 4.14 degrees C. Thermal death trials were also carried out for H. alvei associated with hot-smoked kahawai at 54, 55, 55.5, 56, and 57 degrees C. From the linear regression line (R2 = 0.93) fitted to the data, calculated D values for 54, 55, 56, and 57 degrees C were estimated to be 1.42, 0.74, 0.38, and 0.20 min, respectively, giving a z value of 3.57 degrees C. Results indicate that hot smoking has the potential to eliminate H. alvei from seafood products.

Effect of trenbolene acetate/estradiol implants and estrus suppression on growth performance and carcass characteristics of beef heifers

The effects of estrus suppression (none, oral melengestrol acetate (0.4 mg d−1) or ovariectomy via Willis spay technique) and an anabolic implant (none or Synovex Plus®) on growth performance and carcass characteristics were determined using 90 beef heifers of composite breeding in a 2 × 3 factorial experiment conducted in the last 50 d before slaughter. Spaying caused no morbidity or mortality and resulted in average daily gains (1.37 kg d−1) comparable to heifers fed melengestrol acetate (1.33 kg d−1). Implanting improved (P < 0.05) feed efficiency and increased (P < 0.05) animal gain, ribeye area, carcass weight and yield and reduced (P < 0.05) intramuscular fat deposition but estrus suppression did not. Method of estrus suppression did not influence (P > 0.05) carcass traits. Spaying and implanting represent an effective means of improving returns from heifers, even late in the finishing period. Key words: Ovariectomy, implants, beef heifers, carcass composition

Detection of malignancy associated changes in cervical cell nuclei using feed-forward neural networks

Normal cells in the presence of a precancerous lesion undergo subtle changes of their DNA distribution when observed by visible microscopy. These changes have been termed Malignancy Associated Changes (MACs). Using statistical models such as neural networks and discriminant functions it is possible to design classifiers that can separate these objects from truly normal cells. The correct classification rate using feed-forward neural networks is compared to linear discriminant analysis when applied to detecting MACs. Classifiers were designed using 53 nuclear features calculated from images for each of 25,360 normal appearing cells taken from 344 slides diagnosed as normal or containing severe dysplasia. A linear discriminant function achieved a correct classification rate of 61.6% on the test data while neural networks scored as high as 72.5% on a cell-by-cell basis. The cell classifiers were applied to a library of 93,494 cells from 395 slides, and the results were jackknifed using a single slide feature. The discriminant function achieved a correct classification rate of 67.6% while the neural networks managed as high as 76.2%.

Opening the black box: the relationship between neural networks and linear discriminant functions

Over the last ten years feed-forward neural networks have become a popular tool for statistical decision making. During this time, they have been applied in many fields, including cytological classification. Neural networks are often treated as a black box, whose inner workings are concealed from the researcher. This is unfortunate, since the inner workings of a neural network can be understood in a manner similar to that of a linear discriminant function, which is the standard tool that researchers use for decision making. This paper discusses feed-forward neural networks and some methods to improve their performance for classification problems. Their relationship to discriminant functions will be examined for a simple two-dimensional classification problem.

Insight in schizophrenia and its relationship to psychopathology

A group of 29 patients with DSM-IIIR schizophrenia was studied during acute hospital admission to examine the relationship between changes in insight and positive and negative symptomatology in schizophrenia. On admission, insight scores were obtained using a modification of the SUMD (Amador et al., 1993), and of the degree of psychopathology using the PANSS (Kay et al., 1987). These measures were repeated prior to discharge between 3 and 6 weeks later. Insight improved significantly during the course of in-patient treatment. A relationship between psychopathology and insight level was evident at both assessments, though the pattern was different. Improvement in psychopathology correlated significantly with increased insight into past symptoms but not current illness. When treatment responders were examined there was a significant relationship only with negative symptom improvement and PANSS totals, but not with improvement in positive symptoms. The greater the trend towards negative symptom predominance, the less the tendency to improve in the awareness of current symptoms. This study suggests an inverse relationship with enduring negative symptoms.

Insight and adherence to treatment in psychotic disorders

Patients with psychotic disorders may benefit from strategies designed to improve their adherence to treatment. The assessment of relevant treatment and patient-related variables is an important consideration for the mental health professional.

Metal/dielectric transmission interference filters with low reflectance. 1. Design

For many applications the high reflectance of conventional multilayer interference filters is undesirable. It is possible to design and construct interference filters in which the transmittance and reflectance are independently controlled and in which the reflectance is very low. However, to do this it is necessary to employ absorbing coating materials and, as a result, a reduction in the peak transmittance must be accepted. We describe three different methods for the design of such coatings. Examples are given of a number of bandpass filters, neutral density filters, cutoff filters, and of an x¯(λ) tristimulus filter, all having a low reflectance. This reflectance is frequently 15 to 50 times lower than that of conventional filters.

Inhibition of cytochrome-c oxidase activity during prolonged hypoxia

During acute (< 30 min) hypoxia, cellular respiration is independent of the O2 concentration as long as PO2 remains above a critical value (5-10 Torr). Similarly, state 3 respiration by isolated mitochondria is independent of PO2 above a critical tension of 2-4 Torr. However, rat hepatocytes demonstrate a reversible suppression of respiration and an increase in NAD(P)H concentration during prolonged (2-24 h), but not acute hypoxia [P. T. Schumacker, N. Chandel, and A. G. N. Augusti. Am. J. Physiol. 265 (Lung Cell. Mol. Physiol. 9): L395-L402, 1993]. This study tested whether respiration is similarly inhibited in isolated mitochondria exposed to low PO2 for prolonged periods and whether cytochrome-c oxidase participates in this response. Coupled rat liver mitochondria were incubated under low oxygen conditions (PO2 < 2 Torr) for 2 h. State 3 respiration after reoxygenation to PO2 = 20 Torr was then compared with the value obtained subsequently at 100 Torr. Using succinate and ADP as substrates, we determined that state 3 respiration at 20 Torr was 61.0 +/- 8.4% of the subsequent value at 100 Torr (P < 0.05). By contrast, control mitochondria reoxygenated to 100 Torr first and 20 Torr subsequently showed no significant difference at the two O2 tensions (P = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

The relationship between progeny performance and sire expected progeny differences for central test postweaning gain

On-farm records (84 770) were available to evaluate the relationship between BW and WW with sires' expected progeny difference for central test postweaning gain, both within (EPD) and across (ABC) breeds. Regression coefficients for BW and WW on sire ABC were 0.03 ± 0.01 and 0.25 ± 0.05, respectively. For EPDs, coefficients for BW and WW were either positive (P < 0.05) or not different from zero (P < 0.13) for all breeds. Young sire selection based on central test postweaning gain ABC can be used to change progeny BW and WW. Key words: Central test, sire expected progeny difference, progeny performance

Genetic parameter estimates of conformation and performance traits in station-tested Limousin bulls

Genetic and residual parameters were computed for conformation and performance traits of Limousin bulls in Ontario central test stations. Following editing, data were available on 456 bulls tested in 1990. Genetic parameters for performance traits were similar to those reported in the literature. Heritability of bone score (1 — light to 9 — heavy) was 0.22 ± 0.23. Heritability of a composite muscular development score was 0.51 ± 0.14. Muscular development was positively correlated genetically with all traits studied, including average daily gain (140 d), height, scrotal circumference and bone, and very highly correlated genetically with backfat thickness and weight at end of test. Selection for muscular development using a linear scoring system is feasible, but consideration should be given to correlated responses in other economically important traits. Key words: Multiple-trait analysis, growth and type traits correlations, station-tested beef bulls

Estimation of variance components for lamb weights in three sheep populations

Variance components were estimated for lamb weight at birth, 50 d, and 100 d of age. Data from the Canadian flock recording program for lambs born in 1977 to 1991 for Hampshires (n = 6,395) and Polled Dorsets (n = 29,204) and 1982 to 1991 for Romanovs (n = 3,432) were studied. Observed weights were pre-adjusted for the effects of age of dam, sex of lamb, birth-rearing type, month or quarter of year of birth, parity-lambing interval, and age of dam at first lambing, using estimates derived from a fixed effects model including contemporary groups plus these factors. Pre-adjusting for nuisance variables reduced the number of equations in the model for variance component estimation. A single-trait animal model with derivative-free restricted maximum-likelihood procedures was used. Random effects were additive direct and maternal genetic, litter (common environmental), and error. An alternate model excluded maternal genetic effects. Estimates of litter variance as a proportion of phenotypic variance were of moderate size (.12 to .43) and consistent across breeds and models. The mean correlation between direct and maternal genetic effects, across traits and breeds, weighted by the number of animals, was -.40 (SE = .15). The maternal genetic variance or direct-maternal genetic covariance component, or both, was different from zero (P < .05) for all traits in Hampshires and Polled Dorsets, suggesting that maternal effects were important for weight of lambs even at 100 d of age. Estimates of direct heritability ranged from .05 to .45, varying across traits, breeds, and models.(ABSTRACT TRUNCATED AT 250 WORDS)

An economic comparison of beef cattle genotypes for feedlot traits at their optimal slaughter end point

A bioeconomic model is used to compare beef breeds and crosses for their economic performance in the feedlot. Breeding objectives for each breed and cross are also calculated. Comparisons are made on the basis of the expected purchase-price premium paid for a breed, cross or animal when slaughtered at its profit-maximizing end point. These comparisons are relevant to commercial beef producers who ultimately have to choose between genotypes. Purebred Charolais are expected to capture a premium over purebred Angus of approximately $71 and $45 animar−1 for steers and heifers, respectively. Simmental, Limousin and Hereford purebreds are intermediate, with differences between them relatively small in comparison with the expected effects of errors in model parameters. Crosses between exotic type (Charolais, Simmental and Limousin) and British type (Hereford and Angus) breeds have larger increases in purchase-price premiums over the mid-parent mean than crosses within the types. Averaged economic weights for 1% changes in the mean of +12 g d−1, −80 g d−1 and 0.6% in daily gain, daily feed intake and dressing percentage are $3.7 animal−1, $1.8 animal−1 and $8.4 animal−1, respectively. These are relatively consistent across breeds, crosses and sexes. In contrast, economic weights for fat depth at a constant weight are shown to be nonlinear and therefore are highly dependent on the breed, cross and sex and the slaughter end point at which they are calculated. At the economic optimum slaughter point in the base, exotic breeds and crosses between them tended to have negative economic weights for a reduction in fat depth, whereas British breeds were the opposite. Economic weights tend to be small and positive for a reduction in fat depth in crosses between the two breed types. Key words: Beef cattle, feedlot, end point, optimization, bioeconomic model

A bioeconomic model for comparing beef cattle genotypes at their optimal economic slaughter end point

A bioeconomic model of a feedlot was developed for the comparison of beef cattle genotypes under specified management and marketing conditions. The optimization behavior of commercial feedlot managers is incorporated into the model using optimum economic rotation theory. The days spent in the feedlot (rotation) by a group of animals are derived using this theory so as to maximize an objective function. Differences among breeds in the present value of profits from a single rotation, expressed per animal, represent the expected price premium paid for a feeder animal of a particular breed. Feed requirements and growth rates for a genotype are predicted over time for a specified diet from estimated mature size. Estimates of carcass fatness over time as a function of the energy content of the diet and estimates of dressing percentage over time are used for each genotype. A base model is described that incorporates biological parameters estimated for 11 breeds from a major breed comparison experiment and uses prices of inputs and outputs for Ontario feedlots. Sensitivity of the model to these biological and economic assumptions is shown. When breeds are compared at constant days fed, weight, or fat depth slaughter points, rankings are inconsistent, relative to those when each breed is slaughtered at its optimal economic point. The model can be used to establish appropriate slaughter end points for comparing beef cattle breeds and crosses and to evaluate breeding objectives for feedlot traits in genetic improvement programs.