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Biomedical subjects

J W Mabry

Publications and source records attributed to J W Mabry.

33 records · Page 2Linked to original sources
PubMed1993

Restricted maximum likelihood estimation of variance components from field data for number of pigs born alive.

Variance components for number of pigs born alive (NBA) were estimated from sow productivity field records collected by purebred breed associations. Data sets analyzed were as follows: Hampshire (n = 13,537), Landrace (n = 10,822), and Spotted (n = 3,949). Variance components for service sire, sire of sow, dam of sow, and residual effects on NBA (adjusted for parity) were estimated. The single-trait model included relationships between service sires, sires of sows, and dams of sows. The model was implemented using an expectation maximization (EM) REML algorithm. A sparse-matrix solver was also used. Heritability estimates for NBA were .13, .13, and .12 for Hampshire, Spotted, and Landrace, respectively. Estimates of maternal genetic (co)variances (m2) expressed as a proportion of the phenotypic variance were .05, .01, and .03 for Hampshire, Spotted, and Landrace, respectively. Results indicated that service sires account for 1 to 2% of the total variation for NBA. Genetic effects influencing NBA seem to be small in these data sets, but selection for increased NBA should be effective.

Analysis of Variance↗
PubMed1993

Development of an animal model for across-herd genetic evaluation of number born alive in swine.

An animal model and computer software were developed to conduct across-herd genetic evaluations using data from producers participating in the Sow Productivity Index program of the American Yorkshire Club. The final data set consisted of 61,596 litter records from 1986 to early 1990. The animal model included fixed contemporary group effects and random additive direct, service sire, permanent environmental, and residual effects. Additive genetic relationships among animals were included. A separate relationship matrix for service sires and their sires was also included. A data set similar to the Yorkshire field data was simulated to use in testing the animal model. The simulated data set consisted of 40 herds, each with 120 reproducing dams and either four or five sires. Six generations of simulated data were produced, resulting in 20,605 litter records. These records were then evaluated using the animal model for number of pigs born alive. Finally, correlations between the true breeding values from the simulation and the predicted breeding values were computed. The correlation between the 918 true and predicted sire breeding values was considerably lower for the animal model without a service sire effect than when it was included (.53 vs .74, respectively). However, the difference was cut in half (.66 vs .77) when only sires with greater than five daughter records were included. The high accuracy of the animal model with a random service sire effect indicates that the proposed model adequately accounts for the variation found in records for number of pigs born alive.

Animals↗
PubMed1992

Estimation of direct and maternal heritability and genetic correlation for backfat and growth rate in swine using data from centrally tested Yorkshire boars.

The purpose of this study was to estimate components of variance and covariance for backfat and growth rate in swine tested in central test stations in the United States. Data were collected from 26 central boar test stations from 1984 through 1990. The traits analyzed were backfat adjusted to a 104.5-kg basis and ADG adjusted to a 36-kg on-test weight. Records from 7,951 purebred Yorkshire boars were analyzed. Contemporary groups were defined as boars of a breed that were tested and sold as a common group in a test station. Variance components were estimated using a pseudo-expectation method with a multiple-trait, sire-maternal grandsire model. Direct heritabilities for backfat and ADG were estimated to be .56 and .24, respectively. Direct maternal effects were significant for both backfat and ADG; they accounted for 11 and 23% of the variance, respectively. The additive genetic correlation between backfat and ADG was approximately zero. Within this population of centrally tested Yorkshire boars, heritability seems to be high for backfat and moderate for ADG, with a significant maternal effect on each trait.

Adipose Tissue↗
PubMed1987

A comparison of methods for ranking boars from different central test stations.

Data were received from 24 test stations on 3,999 boars tested in fall 1984 and spring 1985. In an effort to increase the connectedness between stations, one reference sire was selected to produce sons (reference boars) through artificial insemination to be tested in the different stations. Fifty-two reference boars were placed across 17 of the test stations. The performance traits analyzed were average daily gain (ADG) and backfat adjusted to 105 kg (ABF). The methods used to rank boars were: 1) individual record (ADG, ABF), 2) individual record deviated from the contemporary group mean, and 3/4) individual record plus performance of relatives (including/excluding reference boars) using expected progeny differences (EPD) estimated from a reduced animal model (RAM) statistical procedure. Ranks of boars using these four methods of genetic evaluation were compared using Spearman rank correlation methodology. The ranks of the boars changed significantly as the complexity of analysis increased for both ADG and ABF. Rank correlations between individual record and contemporary group deviations for ADG and BF were .47 and .20, respectively. Rank correlations between contemporary group deviations and RAM estimates of EPD for ADG and ABF were .53 and .41, respectively. These were significantly different from 1.0. However, there was no significant difference between rankings based on EPD including vs excluding the reference boars. The importance of rank changes coupled with the increased accuracy of these more complex evaluation methods strongly suggest that best linear unbiased predictors of genetic value be utilized in comparing boars in central test stations.

Animals↗
PubMed1986

Heterotic and maternal effects in L and S growth strain rats: I. Reproductive performance.

A diallel cross between two strains of rats, from the same genetic source, but varying greatly in body size, was made in order to evaluate the following litter traits: number born alive, litter birth weight, number at 21 d of age, 21 d-litter weight, survival from birth to weaning and average birth weight. Least-squares analyses of variance of traits indicated that number born alive, litter birth weight and litter 21 d-weight was influenced greatly by maternal lines and to a lesser extent by paternal lines. Litters from Large line females (L) had greater numbers born alive with heavier litter weights at birth and 21-d than litters from Small line females (S) regardless of sire line. Heterosis was measured as a difference in performance between the hybrids and the mean of the parental lines. Heterosis levels for maternal traits were generally nonsignificant. Analysis of this mating scheme suggested that in this cross between extremes for body size the maternal effects were so great, that any heterotic effects present were not evident.

Alleles↗
PubMed1986

Heterotic and maternal effects in L and S growth strain rats: II. Body weight gains, feed consumption and feed efficiency.

A diallel cross between two strains of rats from the same genetic source, that vary greatly in body size, was made in order to evaluate the differences in individual gain, feed consumption and feed efficiency (gain/feed) from 4 to 15 wk of age. Significant paternal, maternal and sex effects were evident for all weekly gains and feed consumption. These effects were not significant for feed efficiency. Offspring of Large Line (L) rats grew faster and consumed more feed than offspring of Small line (S) rats. Cross-bred mating types (LS and SL) were significantly different as SL rats were faster growing with greater feed consumption than LS rats indicating a significant maternal effect of L female. Heterosis for growth rate was positive and feed consumption negative; however, neither was significant. No significant line of sire, line of dam or heterosis effects on feed efficiency were seen. Analysis of this mating design indicates that increased gain was due to increased feed consumption rather than increased feed efficiency; and, any heterotic effects in this cross between extremes in body size, if present, were masked by maternal effects.

Alleles↗
PubMed1985

Phenotypic and genetic parameters for growth, puberty and composition traits in gilts.

A total of 12 Landrace and 12 Duroc boars were mated randomly to crossbred sows to produce 210 gilts over six farrowing seasons. Each sire was used in only one farrowing season. Biweekly measurements were taken on the live gilts for height, weight, loin depth, shoulder backfat, 10th rib backfat and stifle backfat from 30 to 105 kg. Gilts were removed from confinement units and placed in pasture lots. Estrous detection began when the gilts reached 68 kg and continued until 75% of gilts in a test group had exhibited estrous. Compositional traits were regressed to 105 kg prior to being analyzed. Estimates of genetic parameters were determined using paternal half-sib analysis. Heritability estimates for age at first detectable estrous (ACYCL), tenth rib backfat at 105 kg (BFB) and average daily gain (ADG) were .29, .28 and greater than 1, respectively. Phenotypic correlations between ACYCL and backfat traits were approximately zero, those between ACYCL and growth traits were moderate and desirable and those between growth and backfat traits were low. Genetic correlation between ACYCL and ADG was estimated to be -.67 indicating faster gaining gilts were cycling at a younger age. Estimated genetic correlation between ACYCL and BFB was -.77 indicating that leaner gilts were cycling at a later age. Also, genetic correlation estimated between BFB and ADG was .64 inferring that faster gaining gilts were depositing more backfat.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1983

A comparison of an 8- versus 16-hour photoperiod during lactation on suckling frequency of the baby pig and maternal performance of the sow.

Seventeen crossbred sows were used in a lactation trial to compare the effects of a 16-h photoperiod with an 8-h photoperiod from d 107 of gestation to weaning at 28 d postpartum. Crossbred sows were used to compare the effects of 16-h (n = 8) and 8-h (n = 9) photoperiods on litter and maternal performance traits. Females were moved into two identical farrowing rooms under either 16- or 8-h photoperiods on d 107 of pregnancy, litters were equalized across treatments at birth and the treatments terminated at weaning on d 28 postpartum. Traits evaluated included litter size at birth and weaning, 21-d pig and litter weights, milk yields and composition on d 15, litter survival rates, suckling frequency for a 24-h period on d 13 and percentage of sows returning to estrus and days to estrus after weaning. Pigs exposed to 16 h light nursed more often (P less than .05) than pigs exposed to 8 h light over a 24-h period. This advantage was greatest during the 4-h periods of 1200 to 2000, 0000 to 0400 and 0800 to 1200 h. This difference is perhaps an explanation of why litters exposed to 16 h light weaned more (P less than .05) pigs/litter with heavier (P less than .01) 21-d litter weights. Nonsignificant advantages were also seen in milk yield and litter survival percentage. In addition, sows exposed to 16 h light had higher (P less than .05) total solids content of their milk.

Animal Population Groups↗
PubMed1983

Serum concentrations of pituitary and adrenal hormones in female pigs exposed to two photoperiods.

Serum concentrations of pituitary and adrenal hormones were determined in lactating sows and ovariectomized (OVX) gilts exposed to 8 h (8L:16D) or 16 h of light (16L:8D). In addition serum prolactin (PRL) concentrations were determined after a thyrotropin releasing hormone (TRH) challenge. At 103 +/- 2 d of gestation or 3 wk after ovariectomy of nulliparous gilts on d 7 to 9 of the estrous cycle (d - 10), blood samples were collected from jugular vein cannulae at 30-min intervals for 8 h beginning at 0800 h. Immediately after the last sample, 13 sows and five OVX gilts were assigned to 8L:16D and 14 sows and five OVX gilts were assigned to 16L:8D/d and placed in two identical chambers in the farrowing house. Blood sampling was repeated on d 7, 14 and 21 of lactation in the sows and on d 7, 14, 21 and 28 in the OVX gilts. In Exp. 1, serum cortisol (C) concentrations were similar for sows exposed to 8L:16D (n = 7) and 16L:8D (n = 6) treatments, whereas in Exp. 2, serum C concentrations for sows exposed to 8L:16D (n = 6) were lower than those exposed to 16L:8D (n = 6) on d 7, 14 and 21. Photoperiod failed to influence serum concentrations of PRL, luteinizing hormone (LH) and growth hormone in the lactating sows or PRL in the OVX gilts. Photoperiod also failed to affect mean basal serum concentrations, peak height and peak frequency for PRL and LH in the lactating sows or for PRL in the OVX gilts.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Heterotic and maternal effects on body weight and the parameters of a logistic growth curve of LL and SS rats and their F1 offspring.

Differences in growth curve parameters were evaluated on two growth strains of rats and their reciprocal crosses. Least squares analysis indicated differences (p less than .05) in asymptotic weight, age and weight at the inflection point, the rate parameter, and absolute growth rate. Significant paternal, maternal, and sex influences were evident for each of the four derived traits. Positive significant heterosis was exhibited for each of the parameters of the growth function. Analysis of least square means of body weight also indicated significant differences at all ages from 4 to 15 weeks. Significant line of sire, line of dam and sex effects were expressed for each week body weight was recorded. Although negative, significant heterosis was expressed for body weight at weeks 5 and 6. There was a tendency for heterosis in all other weekly body weight measurements to be positive.

Analysis of Variance↗
PubMed1983

Heterotic and maternal effects on body composition of LL and SS rats and their reciprocals at two ages.

A diallel cross between two genetically similar growth strain lines of rats, varying greatly in body size was made in order to evaluate the differences in carcass composition at 15 and 25 weeks of age. Traits assessed were percentages of dry matter, ash, fat, and protein of empty body weight. Analysis of variance of the components in the model indicated no significant differences in carcass constituents at age 15 weeks except dry matter. Rat carcasses at 25 weeks of age showed an increase in fat per cent (p less than .05) from 15 to 25 weeks of age. A significant maternal influence was expressed for fat per cent in favor of the LL dam and for protein per cent favoring the SS female. Heterosis was more evident (p less than .05) at 25 weeks than 15 weeks for ash, fat, and protein percentages.

Age Factors↗
PubMed1982

Effect of level, source and duration of feeding of supplemental energy in sow diets of metabolic and hormonal traits related to energy utilization in the baby pig.

In each of two trials, 30 sows were assigned to six energy-supplemented diets for 5 (trial 1) or 35 d (trial 2) before farrowing, and the effects on sow milk and pig survival characteristics were examined. Treatments consisted of 1.6 kg/d of a basal diet plus .09, .18 or .27 kg of animal fat/d or .20, .39 or .58 kg of cornstarch/d. Two pigs were killed at birth after blood samples were taken and before suckling. Two pigs per litter were fasted to 24 h and two to 48 h of age. Blood glucose was increased (P less than .05) at birth in pigs from sows fed fat in the 35-d feeding, whereas blood glucose was not different in pigs in the short-term feeding of diets Beta-hydroxybutyrate was highest in blood from pigs in the fat-fed groups after a 48-h fast, which was an indication of increased fat metabolism. Beta-hydroxybutyrate was also higher (P less than .05) after a 24 h fast in livers of pigs from sows fed the highest level of fat in both trials than in livers of pigs from sows fed the same level of cornstarch. There were also treatment differences (P less than .05) in liver glycogen content, oxidation of palmitate to CO2, oxidation of glucose to CO2, number of pigs born dead, birth weight and colostrum total lipids and energy content. No treatment-related differences in levels of FFA, triiodothyronine, thyroxine or glucagon in blood of the offspring were observed.

3-Hydroxybutyric Acid↗
PubMedDate not supplied

Inheritance of porcine stress syndrome.

A total of 66 litters were farrowed in a Yorkshire herd of pigs selected for porcine stress syndrome (PSS) susceptibility. These litters included all possible combinations of matings between stress-susceptible, stress-carrier, and stress-resistant animals. When the data were analyzed by within-litter chi-square analysis, the null hypothesis of recessive inheritance could not be rejected (P less than 0.05). In addition, when the data were analyzed across litters, the null hypothesis of autosomal recessive inheritance could not be rejected (P less than 0.05).

Animals↗
PubMedDate not supplied

Prediction of susceptibility to the porcine stress syndrome.

An experiment designed to compare different predictors of porcine stress syndrome (PSS) was conducted. Animals were exposed to the anesthetic gas, halothane, and their reactions monitored to determine susceptibility or resistance to PSS. Two blood creatine phosphokinase (CPK) traits plus their logs10 were examined as predictors of PSS susceptibility. These were Sigma CPK, Antonik CPK, log Sigma CPK, and log Antonik CPK. The accuracy of these predictors varied from 87 percent to 91 percent in agreement with halothane-determined stress susceptibility. In addition, the relationship of PSS and blood types systems (AO,H) were studied. Two blood types, (+,-/-) and (-,+/+), were consistently stress susceptible while three blood types, (+,a/a), (+,a/c), and (+,c/-), were consistently stress resistant. However, one blood type (+,a/-) contained both stress-susceptible and stress-resistant individuals.

Animals↗