James W Wilton

James W Wilton
University of Guelph | UOGuelph · Department of Animal and Poultry Science

PhD

About

176
Publications
12,664
Reads
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4,051
Citations
Introduction
Additional affiliations
September 1968 - present
University of Guelph
Position
  • Professor Emeritus
November 1967 - August 1968
Cornell University
Position
  • Research Associate

Publications

Publications (176)
Article
The aim of this study was to develop a multiple trait genetic evaluation and selection tool for maternal productivity in beef cattle, particularly in the Hereford breed. Component traits of the maternal productivity index (MPI) were chosen on the basis of their potential to contribute to consistently weaning heavy calves over a sustained herd life,...
Article
Full-text available
Genetic improvement is inherently a long-term process in which progress in the future is built upon improvement in the past. Discounting of future returns is often used in deriving economic values of traits under selection, but this gives a short-term perspective that is in conflict with the long-term nature of genetic improvement. Changes in manag...
Article
Full-text available
Economic benefits from the use of expected progeny of a sample of beef bulls with genetic evaluations were calculated over an integrated supply chain for combinations of price discounts for intramuscular fat and LM area. Fixed backfat finish and marketing at the point of optimized gross margins were considered. An economic model was used to calcula...
Article
The objective of this study was to develop a total economic merit index that identifies more profitable animals using Portugal as a case study to illustrate the recent economic changes in milk production. Economic values were estimated following future global prices and EU policy, and taking into consideration the priorities of the Portuguese dairy...
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The heritability of shear force at 7, 14 and 21 d was estimated from a crossbred population of beef cattle. The population consisted of approximately 1400 crossbred cattle that were predominantly the offspring of Angus, Simmental, Gelbvieh and Piedmontese sires bred to predominantly Angus and Simmental females. Significant breed effects on tenderne...
Book
This book provides concepts, examples and computer programs for the optimization of genetic contributions to animal performance. Topics cover short-term choices of genotypes and long-term improvements of populations, using information on single alleles through to multiple alleles for multiple traits. The focus is on the definition and improvement o...
Article
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Milk yields from monthly tests of 59474 Holsteins cows were used to estimate model parameters of the incomplete Gamma, Y(t) = atbe−ct, Compartmental, Y(t) = me−nt (1 - e−p(t-q)), and Modified Compartmental, Y(t) = ge−ht/(1+e−s(t-r)), models to describe the shape of typical first lactations, where Y(t) is daily milk production on day t. Gamma parame...
Article
The objectives of this study were; to develop a model to simulate the growth of calves marketed as white veal; to use this model to evaluate alternative feeding rations; and to estimate optimal net returns to specialized white veal resources. A set of growth equations for veal calves developed by Van Es of Holland were used in a simulation model to...
Article
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Sixty-six cull cow carcasses were subjected to skeletal separation methods for improving beef tenderness as evaluated using shear force. Forty-one carcasses were used to evaluate the effect on longissimus muscle shear force from skeletal separation at various sites including: (1) the 11th thoracic vertebra, (2) the 12th thoracic vertebra, and (3) t...
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We studied genetic relationships between age-constant live yearling beef bull growth and ultrasound traits and steer carcass traits with dissected steer carcass lean percentage adjusted to slaughter age-, HCW-, fat depth-, and marbling score-constant end points. Three measures of steer carcass lean percentage were used. Blue Tag lean percentage (BT...
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Partial carcass dissection data from 1,031 finished crossbred beef steers were used to calculate heritabilities and genetic correlations among subcutaneous, intermuscular, and body cavity fat percentage and marbling score adjusted to slaughter age-, HCW-, fat depth-, and marbling score-constant endpoints. Genetic correlations were also calculated a...
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Calpastatin (CAST) is a naturally occurring protein that inhibits the normal tenderization of meat as it ages postmortem. A SNP was identified in the CAST gene (a G to C substitution) and genotyped on crossbred commercially fed heifers (n = 163), steers (n = 226), and bulls (n = 61) from beef feedlots, and steers (n = 178) from a University of Guel...
Article
Economic values or weights measure the net economic gain per unit genetic increase of a given trait. These were derived for sow productivity traits for use as weighting factors in a dam line selection index used by purebred or nucleus dam line breeders. The profit function approach was used in order to provide flexibility to alternative production...
Article
Full-text available
among 10 live growth and ultrasound traits measured in yearling beef bulls (n = 2172) and four carcass traits measured in cross- bred finished feedlot steers (n = 1031). Heritabilities ranged from 0.13 (bull ultrasound longissimus muscle width) to 0.83 (year- ling bull hip height). Genetic correlations indicated that selecting yearling bulls for in...
Article
Studies with different populations are required to properly characterize the robustness of associations of polymorphisms in candidate genes with economically important traits across beef cattle populations before this sort of genetic information can be used efficiently in breeding and management decisions. The objective of this study was to evaluat...
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(Co)variance components, direct and maternal breed additive, dominance, and epistatic loss effects on preweaning weight gain of beef cattle were estimated. Data were from 478,466 animals in Ontario, Canada, from 1986 to 1999, including records of both purebred and crossbred animals from Angus, Blonde d'Aquitaine, Charolais, Gelbvieh, Hereford, Limo...
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This study compared the application of a bivariate linear-linear (LL) and a linear-threshold (LT) sire-maternal grandsire model for genetic evaluation of calving ease (CE), using birth weight (BW) as a correlated trait, and assessed the impact of missing records on genetic evaluation of CE in a simulated multi-breed beef population that mimicked ph...
Article
Genetic evaluation strategies were studied using simulated data for three lactation traits in each of two importing and two exporting countries, each running a typical progeny test program. Conversion (CNV), multiple-trait across-country evaluation (MACE) and global animal model (GAM) strategies were considered. Base populations were either unselec...
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Selection responses in sheep were predicted for a maternal index with different emphases on litter size and lamb growth to assess the need for correct economic values. Ratios of economic values for litter size relative to growth from 2 to 200 were tested. Genetic change per generation in market weight of lambs (1.75 to 0.03 kg) was sensitive, but g...
Article
Erratum Erratum to bRandom regression analyses of feed intake of individually tested beef steersQ [Livest. Table 5 Natural logarithm of the marginal posterior density of the data given model M i (ln p(yjM=M i)) and natural logarithm of Bayes factor (ln BF i(j) =ln (p(yjM=M i)/p(yjM=M j)) for comparison of alternative models against the model within...
Article
Objective of the study was to apply random regression models to daily dry matter intakes (DMI) of 376 beef steers fed for up to 168 days for evaluating genetic parameters and the optimum period of test. Steers were tested in a research station in Canada from 1997 to 2001. Models included fixed effects of biological breed type, test group, herd of o...
Article
Data on ultrasound traits (loin depth, average backfat thickness, and loin width) were collected from lambs (n = 3483) across Ontario, born between 1997 and 1999. The data were analysed with a REML procedure in a multiple-trait mixed-animal model to obtain (co)variance component estimates. Analyses of all traits included the additive genetic effect...
Article
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Genetic associations between feed efficiency, growth, and live ultrasound measured body composition traits were studied in purebred beef bulls of six breeds in Ontario bull test stations from 1991 to 2000. Feed traits included average daily feed intake (FI), feed conversion ratio (FCR), and residual feed intake [feed intake adjusted for production...
Article
The effect of herd of origin on genetic evaluation of weight gain of beef bulls in central test stations was examined by univariate and bivariate analyses, which included bull's estimated weight gain on test (BEG) and pre-weaning gain (WG) of bulls and their contemporaries in the herd of origin. Bulls were weighed every 28 days on 112 or 140-day st...
Article
Spring calving beef cows from two genotypes were used in two different trials to examine the effectiveness of visual scoring systems to predict body condition. In trial 1, data on body condition score and ultrasound backfat measurements were collected at three different stages of the production cycle: dry, nursing and weaning. Scoring was by three...
Article
This paper investigates the effect of incorporating risk in the derivation of economic values for livestock trait improvement. Two ways of obtaining economic values were contrasted, without consideration of risk (traditional economic values) and with incorporation of variance of profit and risk attitudes of livestock producers (risk-rated economic...
Article
A terminal-sire index for selecting rams was developed. It combines genetic evaluations for growth traits and carcass characteristics measured ultrasonically on live animals into a single criterion. Weightings for component traits are averages from the indexes of four slightly different breeding goals, determined using economic values and parameter...
Article
Full-text available
Our objectives were to compare a two-step model and a joint procedure via random regression model for evaluating weight gain of beef bulls, weighed every 28 d on 140-d test, and to estimate genetic, environmental, and phenotypic parameters. Two-step analysis consisted of fitting fixed linear regressions to weights of each bull to determine weight g...
Article
Crossbred steers (n = 136) were used to evaluate the effect of management strategy on growth performance, carcass characteristics, and fatty acid composition and palatability attributes of beef. Management strategies included: (1) high grain (75% high moisture corn) finishing (HG), or (2) backgrounding with restricted feeding of an alfalfa silage r...
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Flavour and tenderness are key components contributing to a good eating experience. Intramuscular fat extracted from the longissimus muscle is related to flavour and juiciness, (Fernandez et al., 1999), with marbling related to percent intramuscular fat, (Kazala et al.,1999; Campeneere et al., 1999). Warner-Bratzler shear force measurements have be...
Article
Full-text available
Carcass and growth measurements of finished crossbred steers (n = 843) and yearling ultrasound and growth measurements of purebred bulls (n = 5,654) of 11 breeds were analyzed to estimate genetic parameters. Multiple-trait restricted maximum likelihood (REML) was used to estimate heritabilities and genetic correlations between finished steer carcas...
Article
Computer simulation was used to suggest potential selection strategies for beef cattle breeders with different mixes of clients between two potential markets. The traditional market paid on the basis of carcass weight (CWT), while a new market considered marbling grade in addition to CWT as a basis for payment. Both markets instituted discounts for...
Article
Full-text available
Crossbred steers (n = 136) were used to assess breed differences in growth performance, carcass characteristics, fatty acid composition (total lipids and phospholipids), and palatability attributes of longissimus muscle. A multiple regression model was applied to crossbreeding data to estimate genetic differences between Simmental and Red Angus at...
Article
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In randomized experiments, analysis of covariance is used to increase precision of treatment comparisons. However, for factors that are observational (e.g., breed) or for covariates measured after treatments are applied, it may not be biologically meaningful to calculate treatment means adjusted to a common value of the covariate. For example, in b...
Article
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Genetic evaluations for a multiple-breed population of beef cattle were used to estimate genetic trends for five breeds, and genetic differences and overlap among 14 breeds. Genetic evaluations studied were for direct contributions to birth weight, gain from birth to 200 and 365 d, and maternal contribution to gain from birth to 200 d. Almost all g...
Article
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Data spanning 1980 to 1993 from a multibreed beef herd including primarily eight breeds (Angus, Charolais, Gelbvieh, Hereford, Maine-Anjou, Pinzgauer, Simmental, and Tarentaise) were used to obtain 2,207 records on 200-d weaning gain (WG) and 1,826 records on 200-d milk yield (MY), obtained by machine milking after oxytocin injection. Estimates of...
Article
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Effect of milk yield (MY) on biological efficiency and gross margin as an indicator of profit potential of beef production from birth to slaughter was determined. Data included 9 yr of spring-born single male calves. Biological efficiency was calculated as carcass weight/total feed energy intake, including nonlactating and lactating intakes of cow...
Article
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...
Article
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SUMMARY In the future beef producers could face increased competition from industrial users of North American corn. This would impose a long-term increase in the price of feed for livestock production. The impact of a permanent change in the price of feed on the emphasis of traits in two multi-trait selection procedures is described. Line A conside...
Article
The effects of gender and breed on carcass and chemical composition, and palatability attributes were investigated in 222 Hereford and Simmental bulls and steers. Cattle were progeny of 12 Hereford and 17 Simmental sires using six half-sibs per sire. Bulls were fed a 64% TDN diet to slaughter endpoints of either 4, 7, or 10 mm backfat. Steers were...
Article
Ninety-six Charolais and Limousin steers were used to evaluate 75% grain (whole barley or corn) diets and two slaughter endpoints (7 mm backfat or 568 kg liveweight) in an experiment designed to constrain carcass weights to under approximately 341 kg yet produce optimal beef quality. Each breed was represented by eight progeny from each of six sire...
Article
Genetic parameters of feed intake and efficiency and production traits for lactating beef cows were estimated from data collected from 1980 to 1988 at the Elora Beef Research Centre, Guelph, Ontario. Estimates were obtained using restricted maximum likelihood (REML) with an individual animal model with year - season - treatment, sex of calf, parity...
Article
Genetic parameters of feed efficiency and traits relative to feed efficiency for dry pregnant beef cows were estimated from data collected from 1980 to 1988 at the Elora Beef Research Centre, Guelph, Ontario. Measurements of individual feed intake were available for 90 d immediately before calving. Estimates of parameters were obtained using deriva...
Article
Full-text available
Profit was defined as a function of the genotype of animals and variables controlled by management. Alternative parameterizations of management variables were examined to compare the effect of controlling age at slaughter, weight at slaughter, or fat depth at slaughter. The various parameterizations are shown to result in equivalent economic weight...
Article
Purebred Hereford and Simmental bulls (n = 120), managed similarly to bulls in the Ontario Bull Evaluation Program, were evaluated for reproductive parameters. Four diets, equivalent except for the form of dietary fiber, were fed in a growth performance trial. Diet had no direct effect (P > 0.10) on any of the reproductive variables examined. Of th...
Article
Full-text available
Several features of data structure were studied to determine their effects on variance of prediction error and accuracy of evaluation. Assigning 50 sires with progeny to a portion of 10, 25, or 50 contemporary groups according to a sire model with and without additive genetic relationships, or assigning 50 individuals with their own record to one o...
Article
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Data were obtained from 1980 to 1987 on animals belonging to one of three breeding systems: Hereford, small rotation, and large rotation. Differences among Angus-, Gelbvieh-, Pinzgauer-, and Tarentaise-sired calves within the small rotation system were generally not detected as significant for the preweaning traits of gestation length, calving ease...
Article
An exact expression for the joint probability density function of the phenotypic and genotypic values is examined for the ratio-defined character in which two component characters are assumed to follow a bivariate normal law and to have positive values. An approximation to the function is derived in terms of parameters of two component characters....
Article
Semen was collected from 12 Hereford and 10 Simmental bulls at the conclusion of a 119-day Record of Performance growth trial. Within each breed, the bulls were fed a standard test ration (Diet 1) or an experimental diet consisting entirely of a pelleted concentrate with ground corn cobs as the primary fibre source (Diet 2). Semen was analyzed for...
Article
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Measurements were taken on 216 cows with 469 calvings for weight at weaning, condition at weaning, milk yield, milk fat percentage, milk lactose percentage, milk protein percentage, dry period feed intake, lactation period feed intake, total feed intake, first-service pregnancy rate, pregnancy rate, and days to pregnancy. Measurements were also tak...
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Carcass data on 304 steers and 320 heifers from seven breed of dam groups were analyzed to test equations for predicting weight and proportion of lean content in beef carcasses from measurements of specific cuts. All dams were bred to Angus sires for first calving and to a Simmental sire for second and third calvings. Cattle by Angus sires were sla...
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Carcass data on 304 steers and 320 heifers from seven breed of dam groups were analyzed to test equations designed to predict lean content as weight and proportion in beef carcasses from measurements of the wholesale carcasses. Measurements included cold-carcass weight (CW), average backfat (AB) thickness, longissimus muscle (LM), semimembranosus (...
Article
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Calving records for daughters of 667 Record of Performance tested sires were examined to study factors related to age at first calving. For the 3025 heifers analyzed, mean age (+/- SD) at first calving was 791.5 +/- 161.6 days (26.4 +/- 5.4 months). There were significant effects of the breed of sire on age of heifer at first calving. Daughters of...
Article
The effects of source and level of dietary NDF on intake, ruminal digestion in situ, ruminal fermentation, and total tract digestion were evaluated in Hereford steers using a replicated 5 x 5 Latin square design. Diets contained 62 to 64% TDN and included 1) 80% control concentrate (contained pelleted ground grains) and 20% timothy hay (traditional...
Article
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Ten 394-kg, ruminally fistulated Hereford steers were used in a replicated 5 x 5 Latin square design to evaluate the effects of source and level of dietary NDF on chewing activities during eating and rumination. Diets contained 62 to 64% TDN and included 1) 80% pelleted concentrate (control; contained ground grains, fibrous byproducts, molasses, an...