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Divergent Selection For Heat Loss In Mice: I. Selection Applied And Direct Response Through Fifteen Generations, Merlyn K. Nielsen, L. D. Jones, B. A. Freking, J. A. Deshazer
Divergent Selection For Heat Loss In Mice: I. Selection Applied And Direct Response Through Fifteen Generations, Merlyn K. Nielsen, L. D. Jones, B. A. Freking, J. A. Deshazer
Department of Animal Science: Faculty Publications
Divergent selection for heat production/ loss (kcal•kg-.75•d-1) , measured in 9- to 11-wk-old male mice, was conducted for 15 generations. Heat loss was measured for 15 h on individual animals placed overnight in direct, gradient-layer calorimeters. Selection for high (MH) and low (ML) heat loss and unselected control (MC) occurred in each of three replicates for a total of nine unique lines. Repeatability of the heat loss measurement was .45 and the CV was 10.5%. Cumulative realized selection differentials, averaged for the three replicates, were 145.1 and -105.0 (kcal•kg-.75•d-1) and ranged from …
Divergent Selection For Heat Loss In Mice: Ii. Correlated Responses In Feed Intake, Body Mass, Body Composition, And Number Born Through Fifteen Generations, Merlyn K. Nielsen, B. A. Freking, L. D. Jones, S. M. Nelson, T. L. Vorderstrasse, B. A. Hussey
Divergent Selection For Heat Loss In Mice: Ii. Correlated Responses In Feed Intake, Body Mass, Body Composition, And Number Born Through Fifteen Generations, Merlyn K. Nielsen, B. A. Freking, L. D. Jones, S. M. Nelson, T. L. Vorderstrasse, B. A. Hussey
Department of Animal Science: Faculty Publications
Divergent selection for heat loss (kcal•kg-.75•d-1) , measured in 9- to 11-wk-old male mice, was conducted for 15 generations. Selection for high (MH) and low (ML) heat loss and unselected control (MC) occurred in each of three replicates for a total of nine unique lines. Feed intake in males was measured during Generations 9 through 15. Body mass at commencement of mating in females and at time of measurement of heat loss in males was recorded. Body fat percentage at 12 wk for animals of Generations 6, 10, and 14 was predicted as a function of …
Prediction Of Breeding Values For Tenderness Of Market Animals From Measurements On Bulls, K. L. Barkhouse, L. Dale Van Vleck, Larry V. Cundiff, M. Koohamaraie, D. D. Lunstra, J. D. Crouse
Prediction Of Breeding Values For Tenderness Of Market Animals From Measurements On Bulls, K. L. Barkhouse, L. Dale Van Vleck, Larry V. Cundiff, M. Koohamaraie, D. D. Lunstra, J. D. Crouse
Department of Animal Science: Faculty Publications
Data were tenderness measures on steaks from 237 bulls (Group II) slaughtered after producing freezable semen and on 1,431 related steers and heifers (market animals, Group I ) from Angus, Hereford, Pinzgauer, Brahman, and Sahiwal crosses from the Germ Plasm Evaluation project at the U.S. Meat Animal Research Center. Tenderness was assessed through Warner-Bratzler Shear Force (SF), taste panel tenderness (TPT), marbling score (MS), and myofibrillar fragmentation index (MFI). For all traits, as fraction Bos indicus inheritance increased, implied tenderness decreased. Heritability estimates were generally not significantly different from zero. Genetic correlations generally indicated favorable associations among the traits. The …
Effect Of Selection For Size Of Testes In Boars On Semen And Testis Traits, Ying-Tsorn Huang, Rodger K. Johnson
Effect Of Selection For Size Of Testes In Boars On Semen And Testis Traits, Ying-Tsorn Huang, Rodger K. Johnson
Department of Animal Science: Faculty Publications
The objective of this study was to evaluate the effects of selection for increased size of testes on semen and testis characteristics. Boars from a line selected for increased size of testes at 150 d of age (TS, n = 25) and a randomly selected control line (C, n = 18) were used. Semen was collected three times per week for 3 wk (TRT1) then daily for 3 wk (TRT2) beginning when boar age averaged 276 d. It was followed by a 4-wk period of one collection per week and then the TRT1-TRT2 sequence was repeated. After 64 collections, boars …
Embryonal Survival To 6 Days In Mice Selected On Different Criteria For Litter Size, E. L. De A. Ribeiro, M. A. J. Van Engelen, Merlyn K. Nielsen
Embryonal Survival To 6 Days In Mice Selected On Different Criteria For Litter Size, E. L. De A. Ribeiro, M. A. J. Van Engelen, Merlyn K. Nielsen
Department of Animal Science: Faculty Publications
Embryonal survival was compared in mice resulting from four criteria of selection: LS = selection on number born; IX = selection on an index of ovulation rate and ova success; UT = selection on number born to unilaterally ovariectomized females; and LC = unselected control. Selection occurred for 21 generations with three replicates of the four criteria; thereafter, relaxed selection was practiced. The evaluation was performed using mice of two replicates at Generation 35 and one replicate at Generation 36. Data on a total of 289 female mice were recorded. Females, at an average age of 9 wk, were mated …
Effect Of Variance Of Interaction Effects Of Sire And Herd On Selection For Milk And Fat Yield, G. Dimov, Jeffrey F. Keown, L. Dale Van Vleck, H. D. Norman
Effect Of Variance Of Interaction Effects Of Sire And Herd On Selection For Milk And Fat Yield, G. Dimov, Jeffrey F. Keown, L. Dale Van Vleck, H. D. Norman
Department of Animal Science: Faculty Publications
The animal model for genetic evaluations of dairy cattle by the USDA currently includes a term for interaction effects of sire and herd. The relative magnitude of the variance of that effect was established in the 1960s as 14% of the total variance, but recent research has shown that the proportion is 2% or less. This report compared EBV using either the 14% or the actual estimate from 20 samples of records from herds in California, New York, and Pennsylvania. From 6 to 22% of bulls or cows selected for milk and fat yields based on evaluation with 14% of …
Growth Of Testes And Testicular Morphology After Eight Generations Of Selection For Increased Predicted Weight Of Testes At 150 Days Of Age In Boars, R. R. Harder, D. D. Lunstra, R. K. Johnson, Roman L. Hruska
Growth Of Testes And Testicular Morphology After Eight Generations Of Selection For Increased Predicted Weight Of Testes At 150 Days Of Age In Boars, R. R. Harder, D. D. Lunstra, R. K. Johnson, Roman L. Hruska
Department of Animal Science: Faculty Publications
Weights of testes and epididymides, body weight, and morphometric measurements of testicular tissue of 75 boars of a line selected for eight generations for predicted weight of testes at 150 d of age and 75 boars of a randomly selected control line were used to evaluate the effects of selection on testicular development at 70, 100, 130, 160, and 450 d of age (n = 15 boars per line per age). Body weights for boars of the select and control line did not differ (P <.05) and the shape of the body growth curve was similar for both lines. Boars of the select line had larger testes than control boars at each age (P < .05), but there was a significant line x age interaction. The percentage increase of the select line mean over the control mean for weight of testes was 37% at 70 d, a maximum of 120% at 100 d, and 25% at 450 d. The percentage of the testes made up of seminiferous tubules differed between lines (P <.01). Lines had similar means of approximately 28% at 70 d and 71% at 450 d, but the mean for the select line was larger between 100 and 160 d of age; the greatest difference was 11.6% (control = 43.7, select = 55.3%) at 100 d. After 70 d of age, select-line boars had a greater percentage of seminiferous tubules with lumens that contained elongated spermatids (P <.lo). The proportion of the testes occupied by Leydig cells was greatest at 70 d, declined sharply between 70 and 130 d with a sharper decline in select-line boars, and then declined more gradually from 130 to 450 d of age. We conclude that selection for weight of testes at 150 d resulted in lower age at puberty for boars of the select line.
Growth Of Testes And Testicular Morphology After Eight Generations Of Selection For Increased Predicted Weight Of Testes At 150 Days Of Age In Boars, R. R. Harder, D. D. Lunstra, R. K. Johnson, Roman L. Hruska
Growth Of Testes And Testicular Morphology After Eight Generations Of Selection For Increased Predicted Weight Of Testes At 150 Days Of Age In Boars, R. R. Harder, D. D. Lunstra, R. K. Johnson, Roman L. Hruska
Department of Animal Science: Faculty Publications
Weights of testes and epididymides, body weight, and morphometric measurements of testicular tissue of 75 boars of a line selected for eight generations for predicted weight of testes at 150 d of age and 75 boars of a randomly selected control line were used to evaluate the effects of selection on testicular development at 70, 100, 130, 160, and 450 d of age (n = 15 boars per line per age). Body weights for boars of the select and control line did not differ (P <.05) and the shape of the body growth curve was similar for both lines. Boars of the select line had larger testes than control boars at each age (P < .05), but there was a significant line x age interaction. The percentage increase of the select line mean over the control mean for weight of testes was 37% at 70 d, a maximum of 120% at 100 d, and 25% at 450 d. The percentage of the testes made up of seminiferous tubules differed between lines (P <.01). Lines had similar means of approximately 28% at 70 d and 71% at 450 d, but the mean for the select line was larger between 100 and 160 d of age; the greatest difference was 11.6% (control = 43.7, select = 55.3%) at 100 d. After 70 d of age, select-line boars had a greater percentage of seminiferous tubules with lumens that contained elongated spermatids (P <.l0). The proportion of the testes occupied by Leydig cells was greatest at 70 d, declined sharply between 70 and 130 d with a sharper decline in select-line boars, and then declined more gradually from 130 to 450 d of age. We conclude that selection for weight of testes at 150 d resulted in lower age at puberty for boars of the select line.
Sperm Production In Boars After Nine Generations Of Selection For Increased Weight Of Testis, Thomas A. Rathje, R. K. Johnson, D. D. Lunstra
Sperm Production In Boars After Nine Generations Of Selection For Increased Weight Of Testis, Thomas A. Rathje, R. K. Johnson, D. D. Lunstra
Department of Animal Science: Faculty Publications
Body, testis, and epididymis weights were recorded and homogenization-resistant sperm nuclei were counted to determine daily sperm production and the number of sperm stored within the cauda epididymis (CAUDASP) in 145 boars of a control line (C) and 128 boars of a line selected for increased predicted weight of testis (TS) at 150 d of age. Random samples of boars were evaluated at five ages between 70 and 450 d in Generation 8 and 15 ages between 70 and 296 d in Generation 9. Data were analyzed using an animal model that included the fixed effect of line and the …
Uterine Mass And Uterine Blood Volume In Mice Selected 21 Generations For Alternative Criteria To Increase Litter Size, Merlyn K. Nielsen, R. J. Kittok, Y. L. Kochera Kirby
Uterine Mass And Uterine Blood Volume In Mice Selected 21 Generations For Alternative Criteria To Increase Litter Size, Merlyn K. Nielsen, R. J. Kittok, Y. L. Kochera Kirby
Department of Animal Science: Faculty Publications
Lines of mice, selected for 21 generations using alternative criteria to increase litter size, were evaluated for uterine mass and uterine blood volume to help explain differences in uterine capacity. For this study, mice were sampled from Generation 27, the sixth generation after relaxation of selection. Mice came from all four criteria of selection (LS = selection on number born to unaltered females; M = selection on an index of ovulation rate and ova success; UT = selection on uterine capacity; and LC = unselected control) in each of three replicates (a total of 12 lines). Measurement was at one …
Differences In Pup Birth Weight, Pup Variability Within Litters, And Dam Weight Of Mice Selected For Alternative Criteria To Increase Litter Size, M. A. J/ Van Engelen, Merlyn K. Nielsen, E. L. De A. Ribeiro
Differences In Pup Birth Weight, Pup Variability Within Litters, And Dam Weight Of Mice Selected For Alternative Criteria To Increase Litter Size, M. A. J/ Van Engelen, Merlyn K. Nielsen, E. L. De A. Ribeiro
Department of Animal Science: Faculty Publications
Selection for litter size had been practiced for 21 generations and relaxed selection for 13 generations in mice. Three replicates were used with four selection criteria: index of components (ovulation rate and ova success), uterine capacity, litter size, and an unselected control. Especially with selection for litter size and the index relative to the control, number of pups born had increased, and differences also occurred in mating weight. Dams of the three replicates and their litters were used to evaluate the effects of accumulated selection on pup birth weight, variability in weight of littermates, and dam's weight at mating and …
Ten Generations Of Selection For Predicted Weight Of Testes In Swine: Direct Response And Correlated Response In Body Weight, Backfat, Age At Puberty, And Ovulation Rate, Rodger K. Johnson, Gregg R. Eckardt, Thomas A. Rathje, Denise K. Drudik
Ten Generations Of Selection For Predicted Weight Of Testes In Swine: Direct Response And Correlated Response In Body Weight, Backfat, Age At Puberty, And Ovulation Rate, Rodger K. Johnson, Gregg R. Eckardt, Thomas A. Rathje, Denise K. Drudik
Department of Animal Science: Faculty Publications
Selection for predicted weight of testes at 150 d of age (PWT) was practiced for 10 generations to determine the effect on reproductive and growth traits in swine. Mass selection among boars (line TS) or random selection (line C) was practiced beginning with the F3 generation of a Large White x Landrace composite population. Population size in each line was 40 to 45 litters by 15 sires per generation. Responses were estimated by regressions on cumulative selection differentials for PWT and on generation number and by mixed-model derivative-free REML procedures. The realized heritability of PWT was .35 ± .02 and …
Uterine Capacity And Ovulation Rate In Mice Selected 21 Generations On Alternative Criteria To Increase Litter Size, A. C. Clutter, Y. Kochera Kirby, Merlyn K. Nielsen
Uterine Capacity And Ovulation Rate In Mice Selected 21 Generations On Alternative Criteria To Increase Litter Size, A. C. Clutter, Y. Kochera Kirby, Merlyn K. Nielsen
Department of Animal Science: Faculty Publications
After 21 generations of selection for alternative criteria to change litter size in mice, responses in uterine capacity and ovulation rate were evaluated. Females from Generations 22 and 23 were sampled from 12 lines, representing three replicates of four selection criteria: LS = direct selection on litter size; M = selection on an index of ovulation rate and the proportion of ova shed that resulted in fully formed offspring; UT = selection on uterine capacity measured as litter size from females unilaterally ovariectomized at 4 wk of age; and LC = unselected control. All females in the present evaluation (a …
Changes In Ovulation Rate, Uterine Capacity, Uterine Dimensions, And Parity Effects With Selection For Litter Size In Swine, Luis L. T. Gama, R. K. Johnson
Changes In Ovulation Rate, Uterine Capacity, Uterine Dimensions, And Parity Effects With Selection For Litter Size In Swine, Luis L. T. Gama, R. K. Johnson
Department of Animal Science: Faculty Publications
This study was conducted with random samples of pigs of a line (LS) selected for eight generations for litter size and a randomly selected control line (RS) in the Nebraska Gene Pool population and of crosses of these lines with a Large White- Landrace composite line (I) that was selected for an index of ovulation rate and embryonic survival to 50 d of gestation. Two experiments were done to obtain information on ovulation rate, uterine dimensions, and uterine capacity. In Exp. 1, 103 gilts were slaughtered 9 to 16 d after their second estrus to obtain reproductive tracts for evaluation …
Alternative Methods Of Selection For Litter Size In Mice: Iii. Response To 21 Generations Of Selection, Yvonne Kochera Kirby, Merlyn K. Nielsen
Alternative Methods Of Selection For Litter Size In Mice: Iii. Response To 21 Generations Of Selection, Yvonne Kochera Kirby, Merlyn K. Nielsen
Department of Animal Science: Faculty Publications
Alternative methods of selection to increase litter size in mice have been practiced for 21 generations followed by six generations of relaxed selection. Three replicates were used with four selection criteria: index of components (IX: I = 1.21 x total ovulation rate + 9.05 x ova success), uterine capacity (UT), litter size (LS), and an unselected control (LC). In IX, ovulation rate and ova success were measured by number of corpora lutea and number of pups born/number of corpora lutea, respectively. In UT, uterine capacity was measured and defined as number of pups born to unilaterally ovariectomized (right ovary excised) …
Effect Of Genetic Groups On Estimates Of Additive Genetic Variance, C. Pieramati, L. Dale Van Vleck
Effect Of Genetic Groups On Estimates Of Additive Genetic Variance, C. Pieramati, L. Dale Van Vleck
Department of Animal Science: Faculty Publications
This study examined the effect of genetic grouping on REML estimates of additive genetic variance with an animal model with selected base populations. A simulated population of 40 animals (20 males and 20 females) was followed under selection or random mating conditions for 10 generations. Each population was replicated 20 or 50 times. Genetic grouping reduced estimates of additive genetic variance in populations with selected base animals, whereas grouping had little effect on the estimate in unselected populations. The effect of genetic grouping varied according to the quantity and kind of information that was missing (percentage of deleted data and …
Effects Of Selection Of Data On Estimates Of Breeding Values By Three Methods For Litter Size, Backfat, And Average Daily Gain In Swine, T. E. Long, R. K. Johnson, J. W. Keele
Effects Of Selection Of Data On Estimates Of Breeding Values By Three Methods For Litter Size, Backfat, And Average Daily Gain In Swine, T. E. Long, R. K. Johnson, J. W. Keele
Department of Animal Science: Faculty Publications
Estimated breeding value was calculated based on individual phenotype (SP), an index of individual phenotype and full- and half-sib family averages (SI), or Best Linear Unbiased Rediction (BLUP). Traits considered were litter size (LS), backfat (BF), and ADG. Estimated breeding values were calculated using all data and after deletion of the poorest 5, 10, 15, or 20% of the records for BF and ADG, or 4.8, 8, 13, or 21% of the records for LS. When ail data were used, expected genetic gain from BLUP was greater than for SP by 22,7, and 31% and greater than for SI by …
Ovulation Rate And Twinning Rate In Cattle: Heritabilities And Genetic Correlation, L. Dale Van Vleck, K. E. Gregory, S. E. Echternkamp
Ovulation Rate And Twinning Rate In Cattle: Heritabilities And Genetic Correlation, L. Dale Van Vleck, K. E. Gregory, S. E. Echternkamp
Department of Animal Science: Faculty Publications
Repeated measures of ovulation rate on puberal heifers should be an effective way to select for increased twinning rate. A reliable estimate of the genetic correlation between ovulation and twinning rates is needed to implement such selection and to predict its efficiency. Restricted maximum likelihood was used to estimate genetic correlations from subsets of data collected from the twinning project at the Roman L. Hruska U.S. Meat Animal Research Center. The animal model included numerator relationships among the animals and 6x4 effects of year-season of measurement, age at measurement, and birth group. Genetic correlations between averages of ovulation rates for …
Alternative Methods Of Selection For Litter Size In Mice: I. Characterization Of Base Population And Development Of Methods, A. C. Clutter, Merlyn K. Nielsen, R. K. Johnson
Alternative Methods Of Selection For Litter Size In Mice: I. Characterization Of Base Population And Development Of Methods, A. C. Clutter, Merlyn K. Nielsen, R. K. Johnson
Department of Animal Science: Faculty Publications
Studies on a base population of mice were used to establish an index of components of litter size and a physiological model for measuring uterine capacity to be used subsequently in a selection experiment evaluating alternative methods for practicing selection to increase litter size. Heritability estimates of litter size, ovulation rate and ova success (fraction of ova resulting in fully formed pups) were .18, .33 and .15, respectively. No significant genetic or phenotypic correlation was found between overall ovulation rate and ova success. Phenotypic means and genetic variances were higher for characteristics measured on the right than on the left …
Twinning In Cattle: Ii. Genetic And Environmental Effects On Ovulation Rate In Puberal Heifers And Postpartum Cows And The Effects Of Ovulation Rate On Embryonic Survival, S.E. Echternkamp, K. E. Gregory, G. E. Dickerson, Larry V. Cundiff, R. M. Koch, L. Dale Van Vleck
Twinning In Cattle: Ii. Genetic And Environmental Effects On Ovulation Rate In Puberal Heifers And Postpartum Cows And The Effects Of Ovulation Rate On Embryonic Survival, S.E. Echternkamp, K. E. Gregory, G. E. Dickerson, Larry V. Cundiff, R. M. Koch, L. Dale Van Vleck
Department of Animal Science: Faculty Publications
The potential of ovulation rate before 18 to 21 mo of age in puberal heifers as an indirect selection criterion for twinning rate was considered. Heritability (h2) was .07 ± .03 for single observations and .34 ± .18 for the mean of 7.9 estrous cycles per heifer. Estimated repeatability (r) of ovulation rate was ≤h2, indicating negligible permanent environmental effects. Expected h2 for mean ovulation rate (assuming h2 = r = .07 for single observations) for increasing numbers of estrous cycles would be as follows: 4, .23; 6, .31; 8, .38; and 10, .43. …
Twinning In Cattle: 1. Foundation Animals And Genetic And Environmental Effects On Winning Rate, K. E. Gregory, S. E. Echternkamp, G. E. Dickerson, Larry V. Cundiff, R. M. Koch, L. Dale Van Vleck
Twinning In Cattle: 1. Foundation Animals And Genetic And Environmental Effects On Winning Rate, K. E. Gregory, S. E. Echternkamp, G. E. Dickerson, Larry V. Cundiff, R. M. Koch, L. Dale Van Vleck
Department of Animal Science: Faculty Publications
Foundation cows were selected using prior records from one of two sources, private herds or other projects at the Research Center. Comparing twinning rates before and after selection, the repeatability was lower for those from the fist (.08) than for those from the second (.16) source with a combined value of .12. Realized heritability of single-parity twinning rate estimated from selection of parents and response in daughters of foundation females was .06. Paternal half-sib estimate of heritability of twinning rate was .02 ± .07. Estimates of repeatability computed from calving records of females born in the project indicate that permanent …
Comparison Of Methods Of Predicting Breeding Values Of Swine, J. W. Keele, R. K. Johnson, L. D. Young, T. E. Socha
Comparison Of Methods Of Predicting Breeding Values Of Swine, J. W. Keele, R. K. Johnson, L. D. Young, T. E. Socha
Department of Animal Science: Faculty Publications
Best linear unbiased predictions (BLUP) using information from all known relatives; selection index using phenotype, full-sib average and half-sib average; and phenotypic deviation from contemporary group average were compared as methods of predicting breeding values for days to 100 kg and backfat. Swine records (n = 203,869) from five Hampshire, one Duroc and six Yorkshire herds were obtained from the Nebraska SPF Swine Accrediting Agency. Heritability values used to compute BLUP or index were either estimates based on within-breed offspring on parent regression or values recommended by the National Swine Improvement Federation (NSIF) guidelines. Within-breed estimates of heritability ranged from …
Aspects Of Selection For Performance In Several Environments With Heterogeneous Variances, D. J. Garrick, L. Dale Van Vleck
Aspects Of Selection For Performance In Several Environments With Heterogeneous Variances, D. J. Garrick, L. Dale Van Vleck
Department of Animal Science: Faculty Publications
Dairy cattle evaluation schemes routinely assume homogeneous variance with respect to environment. Increasing evidence suggests the presence of systematic changes in variance components associated with mean level of performance. Best linear unbiased prediction procedures that account for heterogeneity are reviewed. The consequences of incorrectly assuming homogeneity for evaluation are demonstrated for a progeny test and an artificial breeding program that screens dams of sires from heterogeneous populations. Selection assuming homogeneity can be very efficient when heritability, and therefore accuracy of selection, is greatest in the more variable environment. Conversely, appreciable reduction in response results when heritability is greater in the …
Index Selection And Feed Intake Restriction In Swine. I. Effect On Rate And Composition Of Growth, Erik R. Cleveland, R. K. Johnson, R. W. Mandigo
Index Selection And Feed Intake Restriction In Swine. I. Effect On Rate And Composition Of Growth, Erik R. Cleveland, R. K. Johnson, R. W. Mandigo
Department of Animal Science: Faculty Publications
The objectives of this experiment were to determine the effects of index selection for increased average daily gain and decreased backfat, and the effects of restriction of daily feed intake, on rate and composition of growth in swine. A total of 53 barrows from select and control lines were randomly assigned to three feeding levels at 83 d of age, and 33 littermate barrows were slaughtered to establish initial body composition. The trial was approximately 105 d and the feeding levels were twice daily to appetite (AP), once daily feeding of 91% of appetite (AP9l) and once daily feeding of …