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Prediction Of Genetic Values For Feed Intake From Individual Body Weight Gain And Total Feed Intake Of The Pen, A. J. Cooper, Calvin Ferrell, Larry V. Cundiff, L. D. Van Vleck
Prediction Of Genetic Values For Feed Intake From Individual Body Weight Gain And Total Feed Intake Of The Pen, A. J. Cooper, Calvin Ferrell, Larry V. Cundiff, L. D. Van Vleck
Department of Animal Science: Faculty Publications
Records of individual feed intake (FI) and BW gain (GN) were obtained from the Germ Plasm Evaluation (GPE) program at US Meat Animal Research Center (USMARC). Animals were randomly assigned to pens. Only pens with 6 to 9 steers (n = 289) were used for this study (data set 1). Variance components and genetic parameters were estimated using data set 1. Estimated genetic values (EGV) for FI were calculated by 5 methods using single and 2-trait analyses: 1) individual FI and individual GN, 2) individual FI alone, 3) 2-trait with individual GN but with FI missing, 4) individual GN and …
Feed Intake Of Sheep As Affected By Body Weight, Breed, Sex, And Feed Composition, R. M. Lewis, G. C. Emmans
Feed Intake Of Sheep As Affected By Body Weight, Breed, Sex, And Feed Composition, R. M. Lewis, G. C. Emmans
Department of Animal Science: Faculty Publications
The hypotheses tested were that genetic size-scaling for mature BW (A, kg) would reduce variation in intake between kinds of sheep and that quadratic polynomials on u = BW/A with zero intercept would provide good descriptions of the relationship between scaled intake (SI, g/A0.73 d) and degree of maturity in BW (u) across feeds of differing quality. Both sexes of Suffolk sheep from 2 experimental lines (n = 225) and from 3 breed types (Suffolk, Scottish Blackface, and their cross; n = 149) were recorded weekly for ad libitum feed intake and BW; recording of intake was from weaning through, …
Bovine Respiratory Disease In Feedlot Cattle: Phenotypic, Environmental, And Genetic Correlations With Growth, Carcass, And Longissimus Muscle Palatability Traits, G. D. Snowder, L. Dale Van Vleck, L. V. Cundiff, G. L. Bennett, M. Koohmaraie, M. E. Dikeman
Bovine Respiratory Disease In Feedlot Cattle: Phenotypic, Environmental, And Genetic Correlations With Growth, Carcass, And Longissimus Muscle Palatability Traits, G. D. Snowder, L. Dale Van Vleck, L. V. Cundiff, G. L. Bennett, M. Koohmaraie, M. E. Dikeman
Department of Animal Science: Faculty Publications
Bovine respiratory disease (BRD) is the most costly feedlot disease in the United States. Selection for disease resistance is one of several possible interventions to prevent or reduce the economic loss associated with animal disease and to improve animal welfare. Undesirable genetic relationships, however, may exist between production and disease resistance traits. The objectives of this study were to estimate the phenotypic, environmental, and genetic correlations of BRD with growth, carcass, and LM palatability traits. Health records on 18,112 feedlot cattle over a 15-yr period and slaughter data on 1,627 steers over a 4-yr period were analyzed with bivariate animal …
Comparison Of Feed Energy Costs Of Maintenance, Lean Deposition, And Fat Deposition In Three Lines Of Mice Selected For Heat Loss, D. L. Eggert, Merlyn K. Nielsen
Comparison Of Feed Energy Costs Of Maintenance, Lean Deposition, And Fat Deposition In Three Lines Of Mice Selected For Heat Loss, D. L. Eggert, Merlyn K. Nielsen
Department of Animal Science: Faculty Publications
Three replications of mouse selection populations for high heat loss (MH), low heat loss (ML), and a nonselected control (MC) were used to estimate the feed energy costs of maintenance and gain and to test whether selection had changed these costs. At 21 and 49 d of age, mice were weighed and subjected to dual x-ray densitometry measurement for prediction of body composition. At 21 d, mice were randomly assigned to an ad libitum, an 80% of ad libitum, or a 60% of ad libitum feeding group for 28-d collection of individual feed intake. Data were analyzed using 3 approaches. …
Correlated Responses In Maternal Performance Following Divergent Selection For Heat Loss In Mice, J. M. Mcdonald, Merlyn . K. Nielsen
Correlated Responses In Maternal Performance Following Divergent Selection For Heat Loss In Mice, J. M. Mcdonald, Merlyn . K. Nielsen
Department of Animal Science: Faculty Publications
Divergent selection in mice was applied in 3 independent replicates for high (maintenance high; MH) and low (maintenance low; ML) heat loss for 16 generations. An unselected control (maintenance control; MC) was also maintained in all replicates. Selection ceased for 26 generations; heat-loss measurement and selection resumed at generation 42. Lactation performance, dam weight, dam feed intake, and efficiency of production of pup weight were recorded or calculated for MH and ML dams in all 3 replicates at generation 46 or 47 with the objective of determining whether selection for heat loss has created correlated responses in maternal performance. One-half …
Incidence Of Splayleg Pigs In Nebraska Litter Size Selection Lines, J. W. Holl, R. K. Johnson
Incidence Of Splayleg Pigs In Nebraska Litter Size Selection Lines, J. W. Holl, R. K. Johnson
Department of Animal Science: Faculty Publications
Genetic parameters for the splayleg (SL) condition were estimated from 37,673 records of pigs from six lines derived from a Large White–Landrace base population. Random selection for 22 generations was practiced in Lines C1 and C2. Line C2 was derived from C1 at Generation 8. Selection lines were as follows: 1) Line I, selected 11 generations for an index of ovulation rate and embryonic survival followed by 11 generations of selection for litter size; 2) Line IOL, derived from Line I at Generation 8 and which underwent eight generations of two-stage selection for ovulation rate and number of fully formed …
Genetic Parameters For Stayability, Stayability At Calving, And Stayability At Weaning To Specified Ages For Hereford Cows, G. E. Martinez, R. M. Koch, L. V. Cundiff, K. E. Gregory, Stephen D. Kachman, L. Dale Van Vleck
Genetic Parameters For Stayability, Stayability At Calving, And Stayability At Weaning To Specified Ages For Hereford Cows, G. E. Martinez, R. M. Koch, L. V. Cundiff, K. E. Gregory, Stephen D. Kachman, L. Dale Van Vleck
Department of Animal Science: Faculty Publications
Genetic parameters for stayability to six ages (ST1, . . ., ST6), for five measures of stayability to calving (SC2, . . ., SC6), and for five measures of stayability to weaning (SW2, . . ., SW6), were estimated using records of 2,019 Hereford cows collected from 1964 to 1979 from a selection experiment with a control line and three lines selected for weaning weight, yearling weight, and an index of yearling weight and muscle score. The model included birth year of the cow as a fixed effect and the cow’s sire as a random effect. Analyses were performed with …
Follicular Development And Maturation In Gilts Selected For An Index Of High Ovulation Rate And High Prenatal Survival, H.-W. Yen, J. J. Ford, D. R. Zimmerman, R. K. Johnson
Follicular Development And Maturation In Gilts Selected For An Index Of High Ovulation Rate And High Prenatal Survival, H.-W. Yen, J. J. Ford, D. R. Zimmerman, R. K. Johnson
Department of Animal Science: Faculty Publications
Seventy-one 10th-generation gilts from White Line-1 (WL-1 = randomly selected control line) and White Line-2 (WL-2 = selected for an index of ovulation rate and prenatal survival rate) were used to compare the pattern of follicular development and atresia during the follicular phase of the estrous cycle. Gilts were treated with PGF2α on d 13 of the estrous cycle (d 0 of induced follicular development) to induce luteolysis and assigned randomly within line and sire for ovary recovery on d 0, 2, 3, 4, 5, and the day after estrus. Ovaries were evaluated for numbers of corpora albicantia and …
Evaluation Of Gene Expression In Pigs Selected For Enhanced Reproduction Using Differential Display Pcr And Human Microarrays: I. Ovarian Follicles, C. D. Gladney, G. R. Bertani, R. K. Johnson, Daniel Pomp
Evaluation Of Gene Expression In Pigs Selected For Enhanced Reproduction Using Differential Display Pcr And Human Microarrays: I. Ovarian Follicles, C. D. Gladney, G. R. Bertani, R. K. Johnson, Daniel Pomp
Department of Animal Science: Faculty Publications
Differential display PCR (ddPCR) and complementary DNA microarray analyses were used to evaluate gene expression differences in porcine ovarian follicles between a line of pigs selected for an index of ovulation rate and embryo survival (Line I) and its randomly selected control line (Line C). Follicles (4.0 to 7.0 mm) were dissected from ovaries of multiparous sows (n = 27) at either 2 or 4 d following PGF2α analog injection on d 12 to 14 of the estrous cycle. Using ddPCR, differentially expressed bands (n = 282) were excised from gels and 107 were sequenced, yielding 84 unique porcine follicle …
Responses To 19 Generations Of Litter Size Selection In The Ne Index Line. Ii. Growth And Carcass Responses Estimated In Pure Line And Crossbred Litters, D. B. Petry, J. W. Holl, R. K. Johnson
Responses To 19 Generations Of Litter Size Selection In The Ne Index Line. Ii. Growth And Carcass Responses Estimated In Pure Line And Crossbred Litters, D. B. Petry, J. W. Holl, R. K. Johnson
Department of Animal Science: Faculty Publications
Our objective was to estimate responses in growth and carcass traits in the NE Index line (I) that was selected for 19 generations for increased litter size. Differences between Line I and the randomly selected control line (C) were estimated in pure line litters and in F1 and three-way cross litters produced by mating I and C females with males of unrelated lines. Contrasts of means were used to estimate the genetic difference between I and C and interactions of line differences with mating type. In Exp 1, 694 gilts that were retained for breeding, including 538 I and …
Genetic Parameters For Six Measures Of Length Of Productive Life And Three Measures Of Lifetime Production By 6 Yr After First Calving For Hereford Cows, R. M. Koch, L. V. Cundiff, K. E. Gregory, L. Dale Van Vleck
Genetic Parameters For Six Measures Of Length Of Productive Life And Three Measures Of Lifetime Production By 6 Yr After First Calving For Hereford Cows, R. M. Koch, L. V. Cundiff, K. E. Gregory, L. Dale Van Vleck
Department of Animal Science: Faculty Publications
Genetic parameters for length of productive life given the opportunity (LPL|O), measured as days between first calving and disposal conditioned on one of six opportunity groups, L1 through L6 (e.g., L2 is length of productive life in days given the opportunity to live 2 yr after first calving), and lifetime production (LP), measured as the number of calves born (NB), number of calves weaned (NW), and cumulative weaning weight (CW) by 6 yr after first calving, were estimated using records of 1,886 Hereford cows from a selection experiment with three selected lines and a control line. Weaning weights were adjusted …
Number Of Calves Born, Number Of Calves Weaned, And Cumulative Weaning Weight As Measures Of Lifetime Production For Hereford Cows, G. E. Martinez, R. M. Koch, L. V. Cundiff, K. E. Gregory, L. Dale Van Vleck
Number Of Calves Born, Number Of Calves Weaned, And Cumulative Weaning Weight As Measures Of Lifetime Production For Hereford Cows, G. E. Martinez, R. M. Koch, L. V. Cundiff, K. E. Gregory, L. Dale Van Vleck
Department of Animal Science: Faculty Publications
Genetic parameters for lifetime production for cows with the opportunity to produce from 2 through 7 yr of age, as measured by the number of calves born (NB2, …, NB7), the number of calves weaned (NW2, …, NW7), and cumulative weaning weight (CW2,…, CW7), were estimated using data from 3,064 Hereford cows from a selection experiment with a control line (CTL) and three lines selected for weaning weight (WWL), yearling weight (YWL), and an index of yearling weight and muscle score (IXL). Weaning weights were adjusted to 200 d of age and for sex and age of dam. Estimates of …
Responses To 19 Generations Of Litter Size Selection In The Nebraska Index Line. I. Reproductive Responses Estimated In Pure Line And Crossbred Litters, D. B. Petry, Rodger K. Johnson
Responses To 19 Generations Of Litter Size Selection In The Nebraska Index Line. I. Reproductive Responses Estimated In Pure Line And Crossbred Litters, D. B. Petry, Rodger K. Johnson
Department of Animal Science: Faculty Publications
Our objective was to estimate responses in reproductive traits in the Nebraska Index line (I) after 19 generations of selection for increased litter size. Responses were estimated in dams producing pure line, F1, and three-way cross litters. A total of 850 litters were produced over six year-seasons, including 224 pure line litters, 393 F1 litters produced from I and C females mated with DanbredNALandrace (L) or Duroc- Hampshire (T) boars, and 233 litters by F1 L x I and L x C females mated with T boars. Contrasts of means were used to estimate the genetic …
Genetic Response To Selection For Weaning Weight Or Yearling Weight Or Yearling Weight And Muscle Score In Hereford Cattle: Efficiency Of Gain, Growth, And Carcass Characteristics, R. M. Koch, L. V. Cundiff, K. E. Gregory, L. Dale Van Vleck
Genetic Response To Selection For Weaning Weight Or Yearling Weight Or Yearling Weight And Muscle Score In Hereford Cattle: Efficiency Of Gain, Growth, And Carcass Characteristics, R. M. Koch, L. V. Cundiff, K. E. Gregory, L. Dale Van Vleck
Department of Animal Science: Faculty Publications
An experiment involving crosses among selection and control lines was conducted to partition direct and maternal additive genetic response to 20 yr of selection for 1) weaning weight, 2) yearling weight, and 3) index of yearling weight and muscle score. Selection response was evaluated for efficiency of gain, growth from birth through market weight, and carcass characteristics. Heritability and genetic correlations among traits were estimated using animal model analyses. Over a time-constant interval, selected lines were heavier, gained more weight, consumed more ME, and had more gain/ME than the control. Over a weight-constant interval, selected lines required fewer days, consumed …
Evaluation Of Gene Expression In Pigs Selected For Enhanced Reproduction Using Differential Display Pcr And Human Microarrays: I. Ovarian Follicles, C. D. Gladney, G. R. Bertani, R. K. Johnson, Daniel Pomp
Evaluation Of Gene Expression In Pigs Selected For Enhanced Reproduction Using Differential Display Pcr And Human Microarrays: I. Ovarian Follicles, C. D. Gladney, G. R. Bertani, R. K. Johnson, Daniel Pomp
Department of Animal Science: Faculty Publications
Differential display PCR (ddPCR) and complementary DNA microarray analyses were used to evaluate gene expression differences in porcine ovarian follicles between a line of pigs selected for an index of ovulation rate and embryo survival (Line I) and its randomly selected control line (Line C). Follicles (4.0 to 7.0 mm) were dissected from ovaries of multiparous sows (n = 27) at either 2 or 4 d following PGF2α analog injection on d 12 to 14 of the estrous cycle. Using ddPCR, differentially expressed bands (n = 282) were excised from gels and 107 were sequenced, yielding 84 unique porcine …
Evaluation Of Gene Expression In Pigs Selected For Enhanced Reproduction Using Differential Display Pcr: Ii. Anterior Pituitary, G. R. Bertani, C. D. Gladney, R. K. Johnson, Daniel Pomp
Evaluation Of Gene Expression In Pigs Selected For Enhanced Reproduction Using Differential Display Pcr: Ii. Anterior Pituitary, G. R. Bertani, C. D. Gladney, R. K. Johnson, Daniel Pomp
Department of Animal Science: Faculty Publications
The objective of this study was to identify differentially expressed genes in the anterior pituitary (AP) of sows selected for enhanced reproductive phenotypes. Selection in the Index (I) line was based on an index of ovulation rate and embryo survival, whereas random selection was used in the Control (C) line. Average numbers of fully formed piglets at birth were 12.5 ± 1.5 and 9.9 ± 2.0 for Line I and C sows used in this study, respectively. In order to induce luteolysis and synchronize follicle development, sows were injected (i.m.) with 2 mL of prostaglandin F2α analog between d …
Estimates Of Genetic Parameters And Selection Strategies To Improve The Economic Efficiency Of Postweaning Growth In Lambs, G. D. Snowder, L. Dale Van Vleck
Estimates Of Genetic Parameters And Selection Strategies To Improve The Economic Efficiency Of Postweaning Growth In Lambs, G. D. Snowder, L. Dale Van Vleck
Department of Animal Science: Faculty Publications
The objectives of this study were to estimate (co)variance components for growth and feed efficiency measures, and to compare selection strategies to improve economic efficiency of gain. Variance components for pre- and postweaning growth, body weight, and measures of feed efficiency were estimated from data collected on 1,047 Targhee lambs over 7 yr. Approximately 21 d after weaning, lambs were group-fed for 4 wk, with ad libitum access to a diet of 37% whole barley grain and 63% pelleted alfalfa hay. Lambs were then individually fed for 6 wk. Lambs were then returned to group feeding for another 4-wk period. …
Correlated Response In Placental Efficiency In Swine Selected For An Index Of Components Of Litter Size, H. Mesa, T. J. Safranski, R. K. Johnson, W. R. Lamberson
Correlated Response In Placental Efficiency In Swine Selected For An Index Of Components Of Litter Size, H. Mesa, T. J. Safranski, R. K. Johnson, W. R. Lamberson
Department of Animal Science: Faculty Publications
The objective of this study was to evaluate correlated response in placental efficiency to selection for components of litter size. Fourteen generations of selection had resulted in a difference between lines of three fully formed piglets at birth. Gilts from a line selected for an index of components of litter size (S, n =33) and a randomly selected control (C, n =27) were observed at farrowing. At delivery, the umbilical cord of each piglet was double tagged with identically numbered mouse ear tags to allow the piglet’s weight to be matched to the corresponding placental weight. Litter size, placental weight, …
Selection For Maternal Behavior In Mice—Direct And Correlated Responses, Chung-Feng Chiang, Rodger K. Johnson, Merlyn K. Nielsen
Selection For Maternal Behavior In Mice—Direct And Correlated Responses, Chung-Feng Chiang, Rodger K. Johnson, Merlyn K. Nielsen
Department of Animal Science: Faculty Publications
Three generations of divergent selection for a maternal care index (MCI) in mice were practiced in each of three replicates. MCI was recorded for 29–32 dams and litters in each replicate/line subclass. Pups of the top (or bottom) 6– 10 dams in each replicate, depending on number of females in the litters, were selected in high (H) and low (L) MCI lines. At birth, litters with more than 10 pups were standardized to 10 pups whereas litters with no more than 10 pups remained intact. On day 4, 8, 12, and 16 of lactation, time budgets during a 30-min session …
Maternal Behavior In Mice Selected For Large Litter Size, Chung-Feng Chiang, Rodger . K. Johnson, Merlyn K. Nielsen
Maternal Behavior In Mice Selected For Large Litter Size, Chung-Feng Chiang, Rodger . K. Johnson, Merlyn K. Nielsen
Department of Animal Science: Faculty Publications
A total of 96 lactating mice and their pups from each of three replications of lines selected 21 generations for increased litter size (LS) followed by 23–25 generations of random selection and contemporary unselected control lines (LC) were characterized for maternal behavior. Sixteen dams and their pups from each replication of LS and LC lines were sampled. Litter sizes at birth for LS versus LC in the first, second, and third replicates were 17.3 versus 13.2, 15.9 versus 13.1, and 12.3 versus 10.6 pups, respectively, with LS dams averaging 2.87 ± .70 pups more. One-half of the litters were standardized …
Effect Of Duration Of Performance Test On Variance Component Estimates For Lamb Growth Rate, G. D. Snowder, L. Dale Van Vleck
Effect Of Duration Of Performance Test On Variance Component Estimates For Lamb Growth Rate, G. D. Snowder, L. Dale Van Vleck
Department of Animal Science: Faculty Publications
The objective was to determine the effect of periods of adjustment and duration of performance test on estimating genetic variance parameters for ADG. Variance components were estimated from ADG data collected from 1978 to 1984 on a total of 1,047 Targhee ewe and ram lambs at the U.S. Sheep Experiment Station (Dubois, ID). Across all years, lambs averaged 84 ± 9 d of age and 25 ± 5.4 kg of weight when placed on test. Lambs were provided ad libitum access to a commercial pellet of barley grain and ground alfalfa for 14 wk. Every 2 wk, ADG was recorded. …
Direct And Correlated Responses To Two-Stage Selection For Ovulation Rate And Number Of Fully Formed Pigs At Birth In Swine, A. Ruiz-Flores, R. K. Johnson
Direct And Correlated Responses To Two-Stage Selection For Ovulation Rate And Number Of Fully Formed Pigs At Birth In Swine, A. Ruiz-Flores, R. K. Johnson
Department of Animal Science: Faculty Publications
Our objectives were to estimate responses and genetic parameters for ovulation rate, number of fully formed pigs at birth, and other production traits following two-stage selection for increased ovulation rate and number of fully formed pigs. Eight generations of selection were practiced in each of two lines. One selection line was derived from a line that previously selected eight generations for an index to increase ovulation rate and embryonic survival (the IOL pigs). The other selection line was derived from the unselected control line of the index selection experiment (the COL pigs). The control line (C) was continued with random …
Increased Plasma Follicle-Stimulating Hormone Concentrations In Prepubertal Gilts From Lines Selected For Increased Number Of Corpora Lutea, J. J. Ford, D. R. Zimmerman, T. H. Wise, K. A. Leymaster, R. K. Christenson
Increased Plasma Follicle-Stimulating Hormone Concentrations In Prepubertal Gilts From Lines Selected For Increased Number Of Corpora Lutea, J. J. Ford, D. R. Zimmerman, T. H. Wise, K. A. Leymaster, R. K. Christenson
Department of Animal Science: Faculty Publications
Plasma follicle-stimulating hormone (FSH) was evaluated in gilts from two studies in which ovulation rate was increased through direct selection for number of corpora lutea (CL) to determine whether selection for ovulation rate affected FSH secretion during prepubertal development. In the first study, 76 control and 110 selected gilts of University of Nebraska gene pool lines were bled twice during prepubertal development. Plasma FSH concentrations were greater (P < 0.05) at 53 (13.5%) and 75 (21.3%) d of age in selected than in control gilts. In the second study, 254 control gilts, 261 gilts from a line selected for ovulation rate, and 256 gilts from a line selected for uterine capacity were bled at three prepubertal ages. Plasma FSH was greater (P < 0.05), relative to controls, on d 34 (> 24%), 55 (> 13%), and 85 (> 10%) in White Composite gilts selected for either increased ovulation rate or for greater uterine capacity. Unilateral ovariectomy and hysterectomy were performed at …
Genetic Correlations For Litter Weight Weaned With Growth, Prolificacy, And Wool Traits In Columbia, Polypay, Rambouillet, And Targhee Sheep, L. Dale Van Vleck, C. M. Bromley, G. D. Snowder
Genetic Correlations For Litter Weight Weaned With Growth, Prolificacy, And Wool Traits In Columbia, Polypay, Rambouillet, And Targhee Sheep, L. Dale Van Vleck, C. M. Bromley, G. D. Snowder
Department of Animal Science: Faculty Publications
Total litter weight weaned at 120 d postpartum per ewe lambing is often believed to be a measure of range ewe productivity. Genetic correlations for litter weight weaned at 120 d with prolificacy, growth, and wool traits for Columbia, Polypay, Rambouillet, and Targhee sheep were estimated using REML with animal models. Observations per breed ranged from 5,140 to 7,083 for litter weight weaned, from 5,140 to 7,095 for prolificacy traits, from 7,750 to 9,530 for growth traits, and from 4,603 to 18,443 for wool traits. Heritability estimates for litter weight weaned were low and ranged from 0.02 to 0.11. Fraction …
Comparison Of Plasma Fsh Concentration In Boars And Gilts From Lines Selected For Ovulation Rate And Embryonal Survival, And Litter Size And Estimation Of (Co)Variance Components For Fsh And Ovulation Rate, R. K. Johnson, J. J. Ford
Comparison Of Plasma Fsh Concentration In Boars And Gilts From Lines Selected For Ovulation Rate And Embryonal Survival, And Litter Size And Estimation Of (Co)Variance Components For Fsh And Ovulation Rate, R. K. Johnson, J. J. Ford
Department of Animal Science: Faculty Publications
The objective of this research was to determine whether plasma concentration of FSH was genetically correlated with ovulation rate and thus was a useful trait for indirect selection. Blood samples were collected from 619 animals from five lines of pigs. Line I was selected for increased index of ovulation rate and embryonal survival, and Line C was its randomly selected control. Pigs sampled from Lines I and C were from generations 12 and 13. Pigs from three additional lines that were derived from eighth-generation pigs of Lines I and C also were used. These lines were Line C2, a randomly …
Responses In Ovulation Rate, Embryonal Survival, And Litter Traits In Swine To 14 Generations Of Selection To Increase Litter Size, Rodger K. Johnson, Merlyn K. Nielsen, David S. Casey
Responses In Ovulation Rate, Embryonal Survival, And Litter Traits In Swine To 14 Generations Of Selection To Increase Litter Size, Rodger K. Johnson, Merlyn K. Nielsen, David S. Casey
Department of Animal Science: Faculty Publications
Eleven generations of selection for increased index of ovulation rate and embryonal survival rate, followed by three generations of selection for litter size, were practiced. Laparotomy was used to count corpora lutea and fetuses at 50 d of gestation. High-indexing gilts, approximately 30%, were farrowed. Sons of dams in the upper 10% of the distribution were selected. Selection from Generations 12 to 14 was for increased number of fully formed pigs; replacements were from the largest 25% of the litters. A randomly selected control line was maintained. Responses at Generation 11 were approximately 7.4 ova and 3.8 fetuses at 50 …
Genetics Of The Interval From Weaning To Estrus In First-Litter Sows: Correlated Responses, J. Ten Napel, T. H. E. Meuwissen, R. K. Johnson, E. W. Brascamp
Genetics Of The Interval From Weaning To Estrus In First-Litter Sows: Correlated Responses, J. Ten Napel, T. H. E. Meuwissen, R. K. Johnson, E. W. Brascamp
Department of Animal Science: Faculty Publications
The objective of this study was to evaluate relationships between rebreeding performance and growth performance (n = 3,777 gilts) and rebreeding performance and reproductive performance (n = 2,242 sows). Our data were from a selection experiment for shorter intervals from weaning to estrus after the first parity (IWE), involving Dutch Landrace pigs, in which a selection line and a control line without selection were maintained for eight generations. Relationships were evaluated before and after transforming IWE to normal interval (NI; IWE &#; 7 d), prolonged interval (PI; IWE > 7 d), and incidence of a prolonged interval (INC). Heritabilities of NI, …
Genetic And Environmental Parameters For Ovulation Rate, Twinning Rate, And Weight Traits In A Cattle Population Selected For Twinning, K. E. Gregory, G. L. Bennett, L. Dale Van Vleck, S. E. Echternkamp, Larry V. Cundiff
Genetic And Environmental Parameters For Ovulation Rate, Twinning Rate, And Weight Traits In A Cattle Population Selected For Twinning, K. E. Gregory, G. L. Bennett, L. Dale Van Vleck, S. E. Echternkamp, Larry V. Cundiff
Department of Animal Science: Faculty Publications
A project was implemented in 1981 with the objective of increasing twinning rate in cattle. Daughters of foundation sires had twin calves at a frequency of from 8 to 13%, and foundation females had twin calves at an average frequency of 50%. Data were analyzed on twinning rate, ovulation rate, and weight traits. The h2 of ovulation rate increased from .11 to .38 for a single estrous cycle to the mean of eight estrous cycles. From all data, h2 for single observation of ovulation rate and twinning rate were .10 and .09, respectively. The rg between them …
A Simulation Model Including Ovulation Rate, Potential Embryonic Viability, And Uterine Capacity To Explain Litter Size In Mice: Ii. Responses To Alternative Criteria Of Selection, E. L. De A. Ribeiro, Merlyn K. Nielsen, Kreg A. Leymaster, Gary Bennett
A Simulation Model Including Ovulation Rate, Potential Embryonic Viability, And Uterine Capacity To Explain Litter Size In Mice: Ii. Responses To Alternative Criteria Of Selection, E. L. De A. Ribeiro, Merlyn K. Nielsen, Kreg A. Leymaster, Gary Bennett
Department of Animal Science: Faculty Publications
Direct selection for litter size was compared with selection for ovulation rate, ova success, or uterine capacity and for indexes of ovulation rate with ova success or uterine capacity. Selection was simulated for 10 generations in a mouse population based on a model integrating ovulation rate, potential embryonic viability, and uterine capacity. Two indexes including ovulation rate (OR) and ova success (OS) were I = .291 x OR + 2.19 x OS and I = .165 x OR + .736 x OS. Heritabilities for ovulation rate and ova success, assumed in the simulation and to derive the indexes, were .25 …
A Simulation Model Including Ovulation Rate, Potential Embryonic Viability, And Uterine Capacity To Explain Litter Size In Mice: I. Model Development And Implementation, E. L. De A. Ribeiro, Merlyn K. Nielsen, Gary Bennett, Kreg A. Leymaster
A Simulation Model Including Ovulation Rate, Potential Embryonic Viability, And Uterine Capacity To Explain Litter Size In Mice: I. Model Development And Implementation, E. L. De A. Ribeiro, Merlyn K. Nielsen, Gary Bennett, Kreg A. Leymaster
Department of Animal Science: Faculty Publications
Litter size in mice was studied using a model including ovulation rate, potential embryonic viability, and uterine capacity. Simulated results were compared with experimental results from a selection experiment with mice. The four criteria of selection were selection on number born (LS), selection on an index of ovulation rate and ova success (IX), selection on number born to unilaterally ovariectomized females (UT), and unselected control (LC). Comparisons were made to statistics of the base generation and to responses after 13 generations of selection. Phenotypic and genetic statistics for uterine capacity were generated so that simulations produced the experimental means, standard …