Daniel W. Moser

Estimation of genetic parameters and effects of cytoplasmic line on scrotal circumference and semen quality traits in Angus bulls

The purpose of this study was to estimate the heritability of scrotal circumference (SC) and semen traits, genetic correlations between SC and semen quality traits, and the effect of cytoplasmic line on SC and semen traits. Breeding soundness exam (BSE) data were collected on registered Angus bulls at 4 ranches over 7 yr. The American Angus Association provided historical pedigree information to estimate the effect of cytoplasmic line on SC and semen quality traits. After editing, the evaluated data set contained 1,281 bulls with breeding soundness exam data that traced back to 100 founder dams. Data were analyzed using a 2-trait animal model to obtain heritability, genetic correlation between SC and semen quality traits, as well as the effect of cytoplasmic line as a random effect for SC, percent motility (MOT), percent primary abnormalities (PRIM), percent secondary abnormalities (SEC), and percent total abnormalities (TOT) using multiple-trait derivative-free REML. Fixed effects included source ranch and collection year, and test age was used as a covariate. Estimates of heritability for SC, MOT, PRIM, SEC, and TOT were 0.46, 0.05, 0.27, 0.23, and 0.25, respectively. Genetic correlations between SC and MOT, PRIM, SEC, and TOT were 0.36, -0.19, -0.11, and -0.23, respectively. The proportions of phenotypic variance accounted for by cytoplasmic line for SC, MOT, PRIM, SEC, and TOT were <0.001, 0.013, 0.023, 0.002, and <0.001, respectively. Genetic correlations between SC and semen quality traits were low to moderate and favorable. Cytoplasmic line may have a marginal effect on MOT and PRIM, but is likely not a significant source of variation for SC, SEC, or TOT.

The heritabilities, phenotypic correlations, and genetic correlations of lean color and palatability measures from longissimus muscle in beef cattle

Data from a study conducted over 5 yr were analyzed to determine heritability estimates of LM lean color, as measured by subjective scoring and Hunter Colorimeter readings, and palatability, as measured by trained sensory panelists and Warner-Bratzler shear force (WBSF). Phenotypic and genetic correlations were determined between each of the measures of palatability and color. There were 1,066 cattle representing 12 different breeds in the study. Subjective lean color and a* (redness) and b* (yellowness) values were moderately heritable, 0.34 ± 0.122, 0.29 ± 0.115 and 0.28 ± 0.120, respectively, whereas the L* (lightness) was lowly heritable, 0.09 ± 0.087. The heritability of WBSF was moderately heritable ranging from 0.23 ± 0.114 (3 d) to 0.42 ± 0.148 (21 d). Sustained tenderness, as measured by sensory panelists, was found to be moderately heritable ranging from 0.16 ± 0.108 (21 d) to 0.33 ± 0.135 (14 d). Sustained juiciness and beef flavor, as measured by sensory panelists, were found to be lowly to moderately heritable ranging from 0.00 ± 0.089 (21 d) to 0.18 ± 0.105 (14 d) and 0.00 ± 0.080 (7 d) to 0.18 ± 0.110 (21 d), respectively. The significant phenotypic correlations were those between WBSF and subjective lean color, L* value, and a* value; both initial and sustained tenderness as well as beef flavor were correlated with subjective lean color and L* value. Flavor intensity and overall mouthfeel were associated with subjective lean color, L* value, a* value, and b* value. Both a* and b* values were highly correlated genetically with WBSF, -0.71 and -0.72, respectively, and subjective lean color was moderately correlated with WBSF, -0.46. The genetic correlation between subjective lean color and initial tenderness was also high, 0.56, whereas that between a* value and initial tenderness was 0.43, which was similar to that found between b* value and initial tenderness, 0.44. The genetic correlations between subjective lean color, a* value, and b* value with sustained tenderness were all high at 0.58, 0.70, and 0.58, respectively. The genetic correlations between a* value and b* value with beef flavor were low to moderate at 0.12 and 0.19, respectively, whereas that between subjective lean color and beef flavor was high, 0.64. The genetic correlations between a* value, b* value, and lean color with sustained juiciness were all moderate correlations at -0.35, -0.23, and -0.45, respectively. The genetic correlations between a* value and b* value with overall mouthfeel were high at 0.80 and 0.79, respectively, whereas that between subjective lean color and overall mouthfeel was moderate, 0.46. In conclusion, regardless of measurement technique of lean color, it was not only heritable but was also moderately to highly correlated with measurements of palatability in beef from LM.

CASE STUDY : Feed Intake and Performance of Heifers Sired by High- or Low-Residual Feed Intake Angus Bulls 1

ABSTRACT The objective of this project was to investigate the effects of selecting sires for residual feed intake (RFI) on the performance of their daughters. Bulls with low or high estimated breeding values (EBV) for RFI were selected from the Angus Society of Australia sire summary and mated to Angus cross commercial cows at the Kansas State University Cow-Calf Unit in 2005 and 2006. The average EBV of low- and high-RFI bulls were −0.55 and 0.27 kg DM, respectively. Heifers born in 2006 were tested for feed intake in 2 groups (n = 24, n = 26), and heifers born in 2007 (n = 42) were sent to a commercial bull test facility for feed intake and BW gain tests. Body weights were collected every 14 d and used to calculate midtest BW and ADG. Actual feed intake was regressed on midtest metabolic BW and ADG to calculate an expected feed intake for each heifer. Residual feed intake was calculated by subtracting the expected intake from the actual intake. There were no significant differences between heifers sired by lowor high-RFI EBV bulls in RFI, feed intake, G:F, or BW gain (P > 0.05). Heifers in this study were being developed on a less energy-dense diet than the diet used to rank their sires. Genetic differences in RFI calculated in growing bulls may not have been expressed on the lower plane of nutrition of these developing heifers.

Estimation of genetic parameters for udder traits in Hereford cattle

The objective was to estimate genetic parameters for udder traits in Hereford cattle. American Hereford Association (AHA) members initially recorded an overall score based on all udder characteristics. In 2008, the Beef Improvement Federation established guidelines, which were subsequently adopted by the AHA, for evaluating udder suspension and teat size. Therefore, a female was scored for either overall score or udder suspension and teat size for a single lactation, and females may be evaluated for overall score for a parity and then for udder suspension and teat size at a later parity. In all cases, subjective scores were assigned at parturition and ranged from 1 to 9, with a score of 9 considered ideal. Records on 48,191 animals and a 3-generation pedigree with 126,814 animals were obtained from the AHA, Kansas City, MO. These records contained repeated observations for overall score (n = 73,469), suspension (n = 38,412), and teat size (n = 38,412). Because the distribution of scores for all traits peaked at 7, a linear approximation was used in the analysis. Data were modeled using a multiple-trait animal model with random effects of additive genetic and permanent environment, fixed effect of contemporary group (herd-year-season), and a linear covariate for age in days. Heritability estimates (SE) for overall score, suspension, and teat size were 0.32 (0.01), 0.32 (0.01), and 0.28 (0.01), respectively. Through genetic selection for these traits, beef producers could improve udder traits. Repeatability estimates (SE) for overall score, suspension, and teat size were 0.45 (0.005), 0.47 (0.01), and 0.44 (0.01), respectively. Producers should continue evaluating udder traits repeatedly throughout a cows lifetime. The phenotypic correlation (SE) between suspension and teat size was 0.64 (0.004) with 57% of records for suspension and teat size having the same score for both traits. The genetic correlations (SE) between teat size and suspension, overall score and teat size, and overall score and suspension were 0.81 (0.01), 0.71 (0.03), and 0.69 (0.03), respectively, and selection for one trait should result in correlated responses in the other traits. In conclusion, traits were moderately repeatable with scores from a parity being informative for subsequent parities. Because overall score, udder suspension, and teat size were moderately heritable with strong, positive genetic correlations, genetic improvement for these traits can be achieved through selection.

Temperament can be an indicator of feedlot performance and carcass merit in beef cattle

Introduction Cattle producers historically have selected for docile temperaments simply for management convenience because calmer animals are conducive to safe environments for their peers as well as their handlers. As many producers would acknowledge, however, there seems to be a relationship between temperament and cattle health, and calmer cattle tend to frequent the working chute for treatment of disease less often.

Relationships Between Charolais Sire Expected Progeny Differences and Progeny Performance in Commercial Beef Herds1

Data on Charolais-sired calves in 31 commercial herds were analyzed to evaluate progeny performance relative to sire expected progeny differences (EPD). The traits analyzed were BW at birth (BBW; n = 3554) and at weaning (WBW; n = 3604) of crossbred progeny from nationally evaluated sires. Sire BBW EPD and WBW EPD were evaluated as predictors of performance in these commercial herds. Published sire BBW EPD and WBW EPD were averaged and weighted on the numeric accuracy published for each EPD. The average weighted sire BBW EPD was 0.4 kg, and the WBW EPD was 7.0 kg with an average accuracy of 0.79 and 0.75, respectively. Random regression coefficients were estimated for progeny BBW on sire EPD of 1.03 ± 0.09 kg/kg of BBW EPD, and for progeny WBW, 0.66 ± 0.11 kg/kg of WBW EPD. Correlations for sire effect solutions in commercial herds with published sire BBW and WBW EPD were 0.59 and 0.39, respectively. Sire BBW EPD and WBW EPD were favorably related to actual progeny performance. Therefore, selection based on sire EPD should result in change of crossbred progeny performance. This further validates use of EPD as a selection tool for BBW and WBW in commercial herds. However, WBW response was less than expected, possibly a result of management practices in commercial herds compared with seedstock herds.

Genetic variance and covariance and breed differences for feed intake and average daily gain to improve feed efficiency in growing cattle

Feed costs are a major economic expense in finishing and developing cattle; however, collection of feed intake data is costly. Examining relationships among measures of growth and intake, including breed differences, could facilitate selection for efficient cattle. Objectives of this study were to estimate genetic parameters for growth and intake traits and compare indices for feed efficiency to accelerate selection response. On-test ADFI and on-test ADG (TESTADG) and postweaning ADG (PWADG) records for 5,606 finishing steers and growing heifers were collected at the U.S. Meat Animal Research Center in Clay Center, NE. On-test ADFI and ADG data were recorded over testing periods that ranged from 62 to 148 d. Individual quadratic regressions were fitted for BW on time, and TESTADG was predicted from the resulting equations. We included PWADG in the model to improve estimates of growth and intake parameters; PWADG was derived by dividing gain from weaning weight to yearling weight by the number of days between the weights. Genetic parameters were estimated using multiple-trait REML animal models with TESTADG, ADFI, and PWADG for both sexes as dependent variables. Fixed contemporary groups were cohorts of calves simultaneously tested, and covariates included age on test, age of dam, direct and maternal heterosis, and breed composition. Genetic correlations (SE) between steer TESTADG and ADFI, PWADG and ADFI, and TESTADG and PWADG were 0.33 (0.10), 0.59 (0.06), and 0.50 (0.09), respectively, and corresponding estimates for heifers were 0.66 (0.073), 0.77 (0.05), and 0.88 (0.05), respectively. Indices combining EBV for ADFI with EBV for ADG were developed and evaluated. Greater improvement in feed efficiency can be expected using an unrestricted index versus a restricted index. Heterosis significantly affected each trait contributing to greater ADFI and TESTADG. Breed additive effects were estimated for ADFI, TESTADG, and the efficiency indices.

Relationship between residual feed intake and female reproductive measurements in heifers sired by high–or low–residual feed intake Angus bulls1

ABSTRACT Animals need to be feed efficient and reproductively sound for cow-calf producers to optimize profits. The objective of this study was to determine the relationship between feed efficiency and reproductive performance. Angus-based commercial cows were bred to Angus sires that had divergent residual feed intake (RFI) estimated breeding values published by the Angus Society of Australia. Data for this study included 136 crossbred females with multiple parity information. Feed-efficiency measures included RFI and daily DMI. The RFI was calculated by regressing actual feed intake on mid-test metabolic BW and ADG. Heifers were synchronized and mated by AI one time; natural-service sires followed. Pregnancy was determined approximately 60 d after the end of the breeding season. Reproductive measurements were pregnancy rate, first-service conception rate, calving percentage, and calving day. These data showed no relationship between pregnancy rate, first-service conception rate, calving rate, or calving date and phenotypic RFI or DMI (P > 0.10). Heifers that were sired by efficient RFI estimated breeding value bulls tended to have an improved calving rate in parity 2 (P 0.10). This study showed no apparent unfavorable relationship between RFI and fertility as measured by pregnancy rate, first-service conception rate, calving rate, or calving day. Further research with larger numbers of females is needed to determine the relationships between feed efficiency and female reproduction.

Factors affecting student performance in an undergraduate genetics course1

The objective of this study was to determine some of the factors that affect student success in a genetics course. Genetics for the Kansas State University College of Agriculture is taught in the Department of Animal Sciences and Industry and covers Mendelian inheritance, molecular genetics, and quantitative/population genetics. Data collected from 1,516 students over 7 yr included year and semester of the course; age; gender; state of residence; population of hometown; Kansas City metro resident or not; instructor of course; American College Testing Program (ACT) scores; number of transfer credits; major; college; preveterinary student or not; freshman, sophomore, junior, and senior grade point average (GPA); semester credits when taking genetics; class standing when enrolled in genetics; cumulative GPA before and after taking genetics; semester GPA in semester taking genetics, number of semesters between the biology prerequisite and genetics; grade in biology; location of biology course; and final percentage in genetics. Final percentage in genetics did not differ due to instructor, gender, state of residence, major, or college (P > 0.16). Transfer students tended to perform better than nontransfer students (P = 0.09), and students from the Kansas City metro outscored students from other areas (P = 0.03). Preveterinary option students scored higher in genetics than non-preveterinary students (P < 0.01). Seniors scored higher than juniors and sophomores, who scored higher than freshmen (P < 0.02). We observed a tendency for students with higher grades in biology to perform better in genetics (P = 0.06). Students who took biology at Kansas State University performed better in genetics than students who transferred the credit (P < 0.01). There was a negative regression of hometown population on score in genetics (P < 0.01), and positive regressions of ACT score, all measures of GPA, course load, and cumulative credits on final percentage in the course (P < 0.02). To maximize chances for success in genetics, students should take biology from Kansas State, perform well in biology, and wait until at least sophomore standing to enroll in genetics.

Reducing the period of data collection for intake and gain to improve response to selection for feed efficiency in beef cattle

Shortening the period of recording individual feed intake may improve selection response for feed efficiency by increasing the number of cattle that can be recorded given facilities of fixed capacity. Individual DMI and ADG records of 3,462 steers and 2,869 heifers over the entire intake recording period (range 62 to 154 d; mean 83 d; DMI83 and ADG83, respectively), DMI and ADG for the first 42 d of the recording period (DMI42 and ADG42, respectively), and postweaning ADG based on the difference between weaning and yearling weights (PADG) were analyzed. Genetic correlations among DMI42 and DMI83, ADG42 and ADG83, ADG42 and PADG, and ADG83 and PADG were 0.995, 0.962, 0.852, and 0.822, respectively. Four objective functions [feed:gain ratio in steers (FGS) and heifers (FGH); residual gain (RG); and residual feed intake (RFI)] based on DMI83 and ADG83 were considered. Indices using DMI42 and ADG42 (I42); DMI42 and PADG (IPW); and DMI42, ADG42, and PADG (IALL) were developed. Accuracy of the 5 EBV, 4 objectives, and 12 objective × index combinations were computed for all 12,033 animals in the pedigree. Accuracies of indices (IA) were summarized for animals with accuracies for objectives (OA) of 0.25, 0.5, 0.75, and 1. For the RG objective and animals with OA of 0.75, indices I42, IPW, and IALL had IA of 0.63, 0.55, and 0.67, respectively. Differences in IA increased with increased emphasis on ADG83 in the objective. Differences in IA between I42 and IPW usually increased with OA. Relative efficiency (RE) of selection on 42-d tests compared with 83 d was computed based on differences in IA and selection intensities of 5%, 25%, 50%, and 75% under the 83-d scenario, assuming 65% more animals could be tested for 42 d. For 25% selected for the RG objective, and animals with OA of 0.75, indices I42, IPW, and IALL had RE of 1.02, 0.90, and 1.10, respectively. As % selected, OA, and emphasis on DMI increased, RE increased. Relative efficiency varied considerably according to assumptions. One-half of the scenarios considered had RE > 1.15 with a maximum of 2.02 and 77% RE > 1.0. A shorter period of recording DMI can improve selection response for feed efficiency. Selection for the efficiency objectives would not affect PADG. It will be most effective if ADG over the period coinciding with intake recording and ADG over a much longer period of time are simultaneously included in a multiple-trait genetic evaluation with DMI and used in a selection index for efficiency.