James W Wilton

• PhD
• Professor Emeritus at University of Guelph

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,...

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...

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...

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...

Zwambag, A., Kelly, M., Schenkel, F., Mandell, I., Wilton, J. and Miller, S. 2013. Heritability of beef tenderness at different aging times and across breed comparisons. Can. J. Anim. Sci. 93: 307–312. The heritability of shear force at 7, 14 and 21 d was estimated from a crossbred population of beef cattle. The population consisted of approximatel...

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...

Milk yields from monthly tests of 59474 Holsteins cows were used to estimate model parameters of the incomplete Gamma, Y (t) = at b e −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...

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...

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...

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...

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...

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...

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...

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...

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...

(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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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....

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...

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...

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...

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 (...

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...

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...

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...

The fertility of beef bulls which completed performance test in the Ontario Bull Test Program was measured by classification of success as breeders according to surveys of consignors to test, by classification of satisfaction in surveys of users of tested bulls and by measurement of calf crop percentages and birth dates of progeny relative to herdm...

Data from 1,277 single and 85 twin calvings, occurring in both spring and fall from 1980 through 1987, were used to examine the productivity and profitability associated with twin births in beef cattle. Pregnancies in pure and crossbred cattle resulted from both AI and embryo transfer. Cows and calves were confinement-housed. Cows were individually...

Feed intake, weaning weight and direct and maternal contributions to weaning weight were estimated for four breeding systems using data collected between 1979 and 1986 from 773 cow-calf pairs at the Elora Beef Research Centre. Breeding systems included purebred Hereford (HE), small rotational dual purpose (SR) (a four-way rotational crossing system...

Net returns were defined as a function of the monetary returns (revenue) generated by the outputs less the monetary costs generated by the variable inputs. Outputs included total weaning weights of steers and heifers, weight of cull cows and weight of open heifers. Inputs included both feed and nonfeed costs. The net returns equation was incorporat...

A simulation of a selection and mating scheme for beef herds was conducted to compare the genetic progress achieved over 20 generations through evaluation of the animals by best linear unbiased prediction and by a selection index. For comparison, the same selection and mating scheme was applied to the herd using the true genetic values of each anim...

Direct (D) and maternal (M) parameters for birth weight (BW), preweaning gain (WG) and calving ease (CE) were estimated for Angus (AN), Hereford (HE), Charolais (CH), Simmental (SM) and Shorthorn (SS). Data for the study were collected by Agriculture Canada from 1973 to 1983 for use in the National Sire Monitoring Program. Variances were estimated...

Data collected from Canadian central test stations were used to obtain estimates of genetic progress for test station average daily gain (ADG-T), height at hooks (HH), ultrasonically measured backfat thickness midway between the 11th and 12th ribs (FAT) and scrotal circumference (SC). Where possible, records for preweaning average daily gain (ADG-W...

Variance components, heritabilities and genetic and phenotypic correlations were estimated using progeny records of 73 sires on the Young Sire Proving Program (YSPP) of the Canadian Simmental Association. The YSPP was based on random mating of 58 test and 15 reference sires to cows in cooperating herds. Data were collected on several traits but the...

Canadian red and white (RW) and black and white (BW) Holsteins were compared for several production traits based on genetic evaluations of 32 RW and 883 BW bulls, and performance data of 4161 RW and 8691 BW cows. Differences (P < 0.05), favoring BW, were observed for milk and milk fat yield of cows, and for milk fat and milk protein yield evaluatio...

Canadian test station data were used to estimate variance components and heritabilities for average daily gain on test, end-of-test height at hooks, s.c. fat thickness and scrotal circumference for Aberdeen Angus, Charolais, Hereford, Limousin, Shorthorn and Simmental bulls. Preweaning average daily gain records were obtained for tested bulls from...

Two levels of feed during early lactation (70 and 100% of NRC requirements) were used for five groups of genotypes (Herefords, small beef breed crosses, large beef breed crosses, small beef by dairy crosses and large beef by dairy crosses). Days to first ovulation (DFO), days to pregnancy (DP) and pregnancy rates were measured over 2 yr. No interac...

A numerator relationship matrix (A c ) due to sires and dams was compared with a numerator relationship matrix (A i ) due to sires and maternal grandsires in a multiple-trait-reduced animal model (MT-RAM). Best linear unbiased predictors of estimated breeding values (EBV) for 200-d weight (WW) and postweaning gain (PG) (gain from 200 to 365 d of ag...

A Indices developed from performance test data (weight at market finish^(WM), days to market A finish (I~M), rate of economic maturing (K e) and relative growth rate (RGR)) were assessed for associations with feedlot phase gross margin (GM), gross margin per day (GMPD) and feed conver- sion from initial to market weights (FC) at three levels of fee...

Independent data sets were used to develop and validate prediction equations for weight at market finish (WM), days to market finish (DM) and feed intake to market finish (FM). Use of information currently collected at most bull test stations allowed accurate prediction of WM, DM and, to a lesser extent, FM. Regression coefficients were similar acr...

The relationships of performance in time-constant intervals to that in the full feedlot phase of production and of bulls to steers were studied. Monthly records on 43 bulls and 48 steers for gain, ultrasonic backfat, weight and hip height were collected in the period postweaning to an estimated 6 to 7 mm subcutaneous backfat. Information gathered i...

Forty-eight spring-born bulls (representing early-, medium- and late-maturing breed groups) and 30 fall-born bulls (representing medium- and late-maturing breed groups) were randomly assigned to either a control or treatment group within each breed group. Treated bull calves were initially implanted with Ralgro® at approximately 55 d of age and rei...

Embryos were transferred surgically to each uterine horn of 31 recipient cows. Fourteen (45%) became pregnant. Nine of the pregnant recipients calved twins for a rate of 64% twins per pregnancy. Embryos were obtained from nine donors by nonsurgical flushing, with the resulting single and twin calves offspring of six of these. Donors were crossbreds...

Two simulated data sets, representing random mating and positive assortative mating in a beef cattle population over 10 rounds of mating, were each composed of 100 replicates. Three correlated traits were considered; calving ease (CE), 200 day weight (WW) and postweaning gain (PG). All selection practiced in the simulation was random. Positive asso...

The importance of the structure of the beef industry with respect to crossbreeding programs and division into cow-calf and feedlot segments; intensity of production with respect to market standards, feeds and labour; and resource constraints with respect to feed, labour, land and capital; are discussed and quantified where possible. The use of disc...

Diverse breed types were used to study the effects of breeding system, cow weight and milk yield on biological variables in beef production. Breeding systems included purebred Hereford (H), purebred Simmental (S), large rotational beef (LRB), small rotational dual purpose (SRD) and small rotational beef (SRB). Breeding systems differed for most tra...

Records on 616 spring- and fall-calving cows and their calves, of which 227 had feedlot in- formation, were used to study breeding system, cow weight and milk yield effects on various measures of gross margins. Equations involving combinations of production system (cow-calf, feedlot, combined cow-calf and feedlot); beef-to-feed price ratio (low, av...