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1.
Reproductive traits of purebred and crossbred pigs produced in a four-breed diallel mating system using the Duroc, Landrace, Spotted and Yorkshire breeds were collected for five consecutive farrowing seasons (two farrowing seasons/year) beginning in fall 1976. Paternal half-sib heritabilities and genetic correlations for testicular traits (120 boars from 36 sires), serum testosterone (TE) and luteinizing hormone (LH) concentrations before and after treatment with gonadotropin releasing hormone (GnRH; 131 boars from 37 sires) and breeding performance traits (151 boars from 38 sires) were estimated. Heritability estimates were generally small to moderate except for sperm/gram testis (SGT), LH concentrations before (LHO) and at 3 h (LH3) after treatment with GnRH (.73 +/- .48, .61 +/- .46 and 1.19 +/- .45, respectively). A large positive genetic correlation was found for LHO with LH3 (.94 +/- .39), while a negative relationship existed for LH3 with TE concentrations at 3 h after GnRH injection. The genetic correlation between a boar's average first service conception rate and average conception rate also was significant (.82 +/- .54). Genetic correlations among littermate traits would suggest that selection for decreased age at puberty in gilts could cause an increase in LH concentrations in boar offspring, before and after GnRH injection, and may also have adverse effects on their ability to settle females. Selection for increased weight at puberty of gilts could cause TE concentrations of boar offspring to increase while having little effect on their breeding performance.  相似文献   

2.
The genetic influence on body and adipose tissue characteristics of newborn pigs and their correlations to growth rate, BW, body length, backfat thickness and adipocyte size in the outer and inner layers of backfat in 8-d-old Large White piglets were determined. Samples of adipose tissue were obtained by biopsy. Pigs were born to 32 sows mated with the same boar. Heritability and genetic correlations were estimated with dam component of variance; therefore, bias due to common environmental effects cannot be excluded. The heritability estimate for adipocyte volume (.89 +/- .28) was higher than that for backfat thickness at the first and last thoracic vertebrae (.50 +/- .22; .63 +/- .24) and for body weight (.59 +/- .23) at 8 d. Backfat thickness was more closely related genetically and phenotypically to body weight and length than to adipose tissue cellularity. Heritability estimates were .75 +/- .28 for gain from 8 d to weaning and from weaning to 95 d (probably because of common environmental effects) but were .31 +/- .20 for ADG from 95 d to slaughter. Characteristics at 8 d were closely correlated phenotypically with growth rate until weaning. These correlations became lower in the two subsequent periods (to 95 d and to slaughter). Corresponding genetic correlations were nonsignificant.  相似文献   

3.
Backfat thickness, carcass length, area of M. longissimus and carcass composition were determined for 253 Large White barrows and gilts to examine the genetic influence on the main characteristics of the carcass and the correlation of these traits with body measurements and fat characteristics at 8 d of age. Pigs were born to 32 sows mated to the same boar. At the age of 8 d, weight, body length and backfat thickness and cellularity were measured. Pigs were slaughtered at 95 and 145 kg live weight. Heritability and genetic correlations were estimated with dam component of variance. Higher adiposity of carcasses was noted for barrows than for gilts and for those animals slaughtered at the heavier vs at the lighter weight. High h2 values were observed for carcass length (.89 +/- .29), area of the M. longissimus (.67 +/- .26) and backfat thickness at the gluteus medius (.77 +/- .28). Percentage of commercial cuts also had high heritabilities. Phenotypic and genetic correlations between the characteristics at 8 d and backfat thickness, carcass length and M. longissimus area at slaughter were not statistically significant. However, significant phenotypic correlations were found between cellularity of the outer and inner layers at 8 d and percentage of major cuts (e.g., rp = .27 with total fat cuts); cellularity of the outer layer at 8 d also was correlated genetically with carcass composition (e.g., rg = .50 +/- .19 with total fat cuts). Genetic predisposition toward intensive fat deposition was more clearly predicted by cellularity than by thickness of adipose tissue in newborn pigs.  相似文献   

4.
In pork production, the efficiency of dietary protein (AA) use is low, resulting in urinary excretion of large quantities of nitrogen as urea. Use of AA and formation of urea are under enzymatic regulation, suggesting genetic regulation. The current study examined the effects of sire line, sire, and sex on growth characteristics and plasma urea nitrogen (PUN) concentrations in the offspring of 11 Duroc sires and 11 Landrace sires bred to Yorkshire-Landrace dams. Plasma samples were obtained at approximately 107 (age class = 107 d), 128 (age class = 128 d), and 149 (age class = 149 d) d of age from 511 boars, gilts, and barrows group-penned and fed standard finishing diets. Body weight and backfat (BF, mean of 3 measurements) were recorded at the time of blood sample collection. Sex, age class, and their interaction influenced (P < 0.01) BW, BF, and PUN. Predicted traits (i.e., ADG, BW at 21 wk, average daily change in BF, BF at 21 wk, and the mean of 3 PUN measures) were generated. Means (+/-SD) were: ADG, 888 +/- 204 g; BW at 21 wk, 94.2 +/- 12.5 kg; average daily change in BF, 0.083 +/- 0.052 mm; BF at 21 wk, 13.8 +/- 3.0 mm; and the mean of 3 PUN measures, 16.2 +/- 4.4 mg/dL. Predicted weight traits were influenced (P < 0.05) by sire line, and sex influenced (P < 0.01) all predicted traits. Heritability estimates for PUN at 107, 128, and 149 d of age were 0.35 +/- 0.15, 0.21 +/- 0.13, and 0.16 +/- 0.12, respectively. Phenotypic correlations of PUN with growth and fat traits were low. Genetic correlations of PUN measured at 107 d with growth and fat traits were low. However, genetic correlations of PUN measured at 128 or 149 d with growth and fat traits ranged from 0.81 to 0.95. Determination of PUN, as herein, may be of sufficient precision to allow its use in a selection protocol. Selection of pigs with superior growth performance and low PUN may result in a greater efficiency of dietary nitrogen use and a reduced negative environmental impact.  相似文献   

5.
Data from 528 male and 645 female progeny of 63 sires were used to estimate genetic correlations between female and male reproductive traits. Data were from two Hereford herds involved in a long-term selection program of the North Carolina Agricultural Experiment Service. Testicular measurements of circumference, diameter, length and volume were obtained on bulls at 205 and 365 d. Testicular growth measures were defined as differences between 205-and 365-d measurements. Heifers were placed in the breeding herd as yearlings and given two breeding seasons to produce a calf. Traits utilized from females were three age-at-first-breeding traits, two age-at-first-calving traits, two pregnancy rate traits, rebreeding interval and calving interval. Genetic correlations were estimated from half-sib and from sire-daughter analyses. Seventy-five percent or more of the correlations of testicular measurements with pregnancy rats, age at first breeding and age at first calving were in the favorable direction. Average correlations were .62, -.55 and -.66, respectively. For each of the remaining female traits, approximately 50% of the correlations were favorable and the average correlations were small. Correlations were summarized by testicular measurement with favorable correlations given a negative sign. Testicular diameter had more favorable correlations (80%) than length, volume or circumference (70%). However, average correlations were similar (-.31, -.30, -.34 and -.26, respectively). Testicular measurements taken at either 205 or 365 d had the same percentage of favorable correlations (72%), while testicular growth measurements had a slightly higher percentage of favorable correlations (78%). Average correlations of 365-d measures were higher (-.38) than either 205-d or growth measures (-.25 and -.28, respectively). Heritabilities for testicular measurements tended to be moderate to high, while those for female reproduction tended to be low to moderate. These results suggest that selection for increased testicular size would lead to improvement in female reproduction, particularly an increase in calving rate and a decrease in age at first breeding.  相似文献   

6.
Growth and carcass measurements were made on 2,411 Hereford steers slaughtered at a constant weight from a designed reference sire program involving 137 sires. A second data set consisted of ultrasound measures of backfat (USFAT) and longissimus muscle area (USREA) from 3,482 yearling Hereford cattle representing 441 sires. Restricted maximum likelihood procedures were used to estimate genetic parameters among carcass traits and live animal weight traits from these two separate data sets. Heritability estimates for the slaughter weight constant steer carcass backfat (FAT) and longissimus muscle area (REA) were .49 and .46, respectively. In addition, FAT had a negative genetic correlation with REA (-.37), weaning weight (-.28), and yearling weight (-.13) but positive with marbling (.19) and carcass weight (.36). Marbling was moderately heritable (.35) and highly correlated with total postweaning average daily gain (.54) and feedlot relative growth rate (.62). Heritability estimates for weight constant USFAT and USREA were .26 and .25, respectively. The genetic correlation between weight constant USFAT and USREA was positive (.39), indicating that in these young animals USFAT does not seem to be an indication of maturity. Mean USFAT measures and variability were small (.48 +/- .17 cm, n = 3,482). Results indicate that carcass fat on slaughter steers and ultrasound measures of backfat on young breeding animals may have different relationships with growth and muscling. These relationships need to be explored before wide scale selection based on ultrasound is implemented.  相似文献   

7.
This study was intended to examine whether serum IGF-I concentration is appropriate for use as a physiological predictor for genetic improvement of meat production and meat quality traits in pigs. Heritabilities and genetic correlations were estimated for these traits. The Duroc breed used in this study was selected for seven generations for average daily BW gain (DG) from 30 to 105 kg of BW, loin-eye muscle area (EM), backfat thickness (BF), and intramuscular fat (IMF) content. Serum IGF-I concentration of boars and gilts at the fourth generation of selection and that of boars, gilts, and barrows from the fifth to seventh generations of selection were measured at 8 wk (IGFI-8W) for 832 animals and again at the time they reached 105 kg of BW (IGFI-105KG) for 834 animals. A multivariate REML procedure was used to estimate genetic parameters with a model incorporating generation of selection, sex, common environmental effect of litter, and individual additive genetic effects. Heritability estimates for IGFI-8W and IGFI-105KG were 0.23 +/- 0.02 and 0.26 +/- 0.03, respectively. The estimates of common environmental effect for IGFI-8W and IGFI-105KG were 0.20 +/- 0.02 and 0.03 +/- 0.01, respectively. Positive genetic correlations were estimated between IGFI-8W and DG (0.26 +/- 0.08), EM (0.22 +/- 0.10), and IMF (0.32 +/- 0.10). Moreover, the positive genetic correlation between IGFI-105KG and EM was 0.42 +/- 0.08. These results indicate that serum IGF-I concentration at an early stage of growth was effective for prediction of IMF, but it was not a reliable physiological predictor of genetic merit of meat production traits.  相似文献   

8.
Data were collected from 1,245 Duroc boars and 527 Yorkshire boars. This represents 128 Duroc and 57 Yorkshire sires. Body weights, testis length and combined testes width at 140 and 168 d were obtained. Of these boars, 432 were castrated at a later age to evaluate relationships between in situ measures and excised testis traits. Heritabilities for testis length, width and volume at 140 d ranged from .16 to .25 in both Duroc and Yorkshire data. Heritabilities for testis measurements at 168 d ranged from .16 to .36 in both data sets. Favorable negative genetic relationships were found between in situ testis measures and age to 104 kg and backfat adjusted to 104 kg. Correlations among in situ measurements were high and positive. All excised testicular traits were highly heritable except for right epididymis weight and excised testis width. Correlation estimates among excised testis traits were generally positive. Phenotypic and genetic correlation estimates between live (in situ testis and growth performance traits) measurements and excised testis traits were generally favorable. This study suggests that in situ testis measurements should be good predictors of sperm production. It also suggests that selection for testis size should not be antagonistic to selection for growth performance traits.  相似文献   

9.
Nine blood samples were taken at 30-min intervals from 36 Landrace X Large White boars at each of eight ages (42, 56, 70, 84, 98, 112, 126 and 140 d). Serum concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone (T) and estradiol-17 beta (E2) were quantified by radioimmunoassay procedures. The maximum concentration of LH and the age at maximum concentration were predicted for each boar. Variability of LH samples was described for each boar by the pooled within age variance among LH samples and by the number of LH peaks. Measurements of testicular development taken at 140 d of age included: in situ testis width and length, excised testis weights and histological traits of excised testes (seminiferous tubule diameter, percentage of tubules with a lumen and percentage of tubules with active spermatogenesis). Pooled within line correlations were calculated with data from boars selected for either high or low testis weight. Correlations among the testicular traits ranged from .45 to .88. Luteinizing hormone concentration (mean over all ages) was related to measures of testicular development (r = .24 to .49). Concentrations of LH from 42 to 84 d of age were more highly correlated with testicular traits than were the concentrations from 98 to 140 d.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

10.
Genetic parameters and trends for length of productive life (LPL), lifetime number of piglets born alive per year (LBAY), lifetime number of piglets weaned per year (LPWY), lifetime litter birth weight per year (LBWY) and lifetime litter weaning weight per year (LWWY) were estimated using phenotypic records of 3085 sows collected from 1989 to 2013 in a commercial swine farm in Northern Thailand. The five‐trait animal model included the fixed effects of first farrowing year‐season, breed group and age at first farrowing. Random effects were animal and residual. Heritability estimates ranged from 0.04 ± 0.02 for LBWY to 0.17 ± 0.04 for LPL. Genetic correlations ranged from 0.66 ± 0.14 between LPL and LBAY to 0.95 ± 0.02 between LPWY and LWWY. Spearman rank correlations among estimated breeding values for LPL and lifetime production efficiency traits tended to be higher for boars than for sows. Sire genetic trends were negative and significant for all traits, except for LPWY. Dam genetic trends were positive and significant for all traits. Sow genetic trends were mostly positive and significant only for LPWY and LBWY. Improvement of LPL and lifetime production efficiency traits will require these traits to be included in the selection indexes used to choose replacement boars and gilts in this population.  相似文献   

11.
Data from Thai Landrace sows were used to estimate genetic parameters for reproduction and production traits in first and later parities. The reproduction traits investigated were total number of piglets born per litter (TB), number of stillborn piglets (SB), and number of piglets born alive but dead within 24 h (BAD). The reproduction data pertained to 12,603 litters born between 1993 and 2005. The production measures were ADG and backfat thickness (BF); these were recorded in 4,163 boars and 15,171 gilts. Analyses were carried out with a multivariate animal model using average information REML procedures. Heritability estimates of reproduction traits for first parity were 0.03 +/- 0.02 for TB, 0.04 +/- 0.02 for SB, and 0.06 +/- 0.02 for BAD. For later parities, they were 0.07 +/- 0.01 for TB, 0.03 +/- 0.04 for SB, and 0.02 +/- 0.01 for BAD. Heritability estimates for production traits were 0.38 +/- 0.02 for ADG and 0.61 +/- 0.02 for BF. Genetic correlations between ADG and TB tended to be favorable, and genetic correlations between BF and TB tended to be unfavorable in all parities. However, BF was genetically correlated unfavorably with SB in later parities, and the genetic correlations between TB and BAD tended to be unfavorable in all parities. The genetic correlations of TB, SB, and BAD between first and later parities were 0.85 +/- 0.13, 0.79 +/- 0.16, and 0.71 +/- 0.24, respectively. Selection for high growth rate will probably increase TB, and selection for low BF will decrease TB and increase SB. The results obtained also indicated that BAD will increase if there is selection pressure for high TB.  相似文献   

12.
The objective was to estimate correlations of gilt estrus, puberty, growth, composition, and structural conformation traits with first-litter reproductive measures. Four groups of gilts (n = 1,225; Genetic Improvement Services of NC, Newton Grove, NC) entered the NC Swine Evaluation Station (Clayton, NC) averaging 162 d of age and were observed daily for symptoms of estrus. Once symptoms of first estrus were observed in 70% of gilts, recording of symptoms of estrus in all gilts occurred every 12 h for 30 d, utilizing fence-line boar contact. Subjective estrous traits were maximum and total strength of standing reflex, as observed with and without the presence of a boar, and strength of vulva reddening and swelling. Objective estrous traits consisted of vulva redness, vulva width, length of estrus, and age at puberty. Growth and composition traits included BW at puberty, days to 114 kg, and 10th rib backfat and LM area at 114 kg and at puberty. Subjective structural conformation traits were muscle mass, rib width, front leg side view, rear leg side view, front legs front view, rear legs rear view, and locomotion. First-litter sow traits included if gilt farrowed (Stay), age at first farrowing (AFF), total number of piglets born (TNB), and weaning to conception interval (WCI). Variance components were estimated using an animal model with AIREMLF90 for linear traits and THRGIBBS1F90 for categorical traits. Heritability estimates for Stay, AFF, and TNB were 0.14, 0.22, and 0.02, respectively. Genetic correlations between length of estrus, the standing reflex traits, and age at puberty with Stay were 0.34, 0.34 to 0.74, and -0.27, respectively, and with AFF were -0.11, -0.04 to -0.41, and 0.76, respectively. Days to 114 kg had genetic associations with Stay, AFF, and TNB of 0.52, -0.25, and -0.08, respectively. Backfat at 114 kg had genetic correlations with Stay, AFF, and TNB of -0.29, 0.14, and 0.47, respectively. Vulva redness and TNB were negatively correlated phenotypically (r = -0.14) and genetically (r = -0.53). Associations between structural conformation traits with Stay, AFF, TNB, and WCI were generally low to moderate and favorable. Selection for longer length of estrus, stronger standing reflex, or younger age at puberty would increase the proportion of gilts that farrow and reduce age at first farrowing.  相似文献   

13.
The purpose of this study was to estimate genetic parameters for ADG, backfat thickness and loin eye area (LEA), and measures of feed intake and efficiency for purebred Large White boars born from 1990 to 1997. Boars from 60% of the litters were culled at weaning based on a maternal breeding value (index) of the dam, and remaining boars (n = 26,706) were grown to 100 d of age. Selection of boars for individual pen testing was based on a combination of growth and maternal indices. Boars were fed a corn-soybean meal diet that was 1.14% lysine, 19% protein, and 3,344 kcal/kg ME for approximately 77 d. Boars were weighed at the beginning and end of the test, and feed intake was recorded. Daily feed intake (DFI), ADG, and feed:gain ratio (FG) were computed. Four measures of residual feed intake (RFI) were estimated as the difference between actual feed intake and that predicted from models that included 1) initial test age and weight and test ADG (RFI1); 2) initial test age and weight, test ADG, and backfat (RFI2); 3) initial test age and weight, test ADG, and LEA (RFI3); and 4) initial test age and weight, test ADG, backfat, and LEA (RFI4). Genetic parameters were estimated using an animal model and single- or multiple-trait DFREML procedures. Models included fixed effects of contemporary groups and initial test age as a covariate and random animal and litter effects. Heritability estimates for test ADG, DFI, FG, backfat, LEA, RFI1, RFI2, RFI3, and RFI4 were .24, .23, .16, .36, .24, .17, .11, .15, and .10, respectively. Genetic correlations between ADG and backfat, ADG and LEA, ADG and DFI, and ADG and FG were .37, .36, .82, and -.32, respectively. Genetic correlations between ADG and measures of residual feed intake ranged from .11 to .18. Genetic correlations of backfat with LEA, DFI, and FG were -.27, .64, and .40, respectively. Genetic correlations of backfat with RFI measures were higher when backfat was not included in the estimation of RFI. Genetic correlations for LEA with DFI and FG were 0 and -.52, respectively. Genetic correlations for LEA with RFI measures were all negative and ranged from -.31 to -.51. Genetic correlations indicate that selection for reduced RFI could be made without adversely affecting ADG. Backfat should also decrease, and LEA should increase. The amount of change in backfat or LEA would depend on the measure of RFI used.  相似文献   

14.
A synthetic progestogen (altrenogest) was fed to 24 Yorkshire X Duroc boars to determine effects on body growth, serum testosterone, and testicular characteristics. Boars from six litters (blocks) were allotted randomly to one of four treatment groups at 12 wk of age. Treatment groups were: controls, altrenogest fed for 3 wk, altrenogest fed for 6 wk and altrenogest fed for 9 wk. Treatment began at 15 wk of age at a daily dose of 20 mg X boar-1. Although there were no differences among treatment groups for gain and feed intake, boars fed altrenogest for 6 and 9 wk tended to consume more feed and were less (P less than .05) efficient than boars fed altrenogest for 3 wk or controls. Boars fed altrenogest for 3, 6 and 9 wk maintained lower (P less than .05) peripheral serum testosterone concentrations than controls from 15 to 24 wk of age. However, serum testosterone increased after altrenogest withdrawal in the 3- and 6-wk treatment groups but did not reach control concentrations by 24 wk. Boars fed altrenogest for 9 wk maintained serum testosterone below 1 ng/ml during the treatment period. Despite lower concentrations of serum testosterone in altrenogest-treated boars, backfat thickness was similar to controls, perhaps suggesting a slight anabolic effect of altrenogest on nutrient partitioning. Testicular weights and volumes at 24 wk decreased (P less than .001) linearly with increased duration of altrenogest feeding. Serum testosterone and estradiol in testicular venous effluent at castration were lower (P less than .01) in altrenogest-treated boars than in controls. These data demonstrate that feeding altrenogest inhibits both testicular growth and steroidogenesis of boars without altering body growth or backfat thickness.  相似文献   

15.
Mass selection for increased weight at 200 d of age was conducted for six generations in a line of Landrace pigs. In the select line, the heaviest nine boars and 18 gilts were selected from each generation to produce the subsequent generation. A contemporaneous control line was maintained by randomly selecting a son from each sire and a daughter from each dam to attain a line size of five boars and 10 gilts. Inbreeding coefficients averaged .182 and .191 for the select- and control-line pigs and .150 and .162 for the select- and control-line dams, respectively, in the sixth generation. The 200-d weights and ultrasound backfat thickness data were collected from 1,022 pigs of 2,181 pigs farrowed. These pigs were sired by 92 boars and out of 210 sows. The generation interval was 13 mo. Twelve traits were studied: weights at birth and at 21, 35, 70, 154, and 200 d of age; daily gains from birth to 35 d, 35 to 70 d, 70 to 154 d, and 154 to 200 d; ultrasound backfat thickness at 200 d; and ultrasound backfat thickness adjusted for 200-d weight. Total weighted cumulative selection differential for 200-d weight was 88.7 kg. Realized heritability for 200-d weight was .26 +/- .08 with an average response of 4.2 +/- 1.3 kg/generation. Correlated responses resulted in increases for all weights and daily gains evaluated. Although ultrasound backfat thickness at 200 d increased in the select line compared to the control line, it was not altered by selection for 200-d weight when adjusted for 200-d weight.  相似文献   

16.
Real time ultrasound (RTU) measures of longissimus muscle area and fat depth were taken at 12 and 14 mo of age on composite bulls (n = 404) and heifers (n = 514). Carcass longissimus muscle area and fat depth, hot carcass weight, estimated percentage lean yield, marbling score, Warner-Bratzler shear force, and 7-rib dissectable seam fat and lean percentages were measured on steers (n = 235). Additive genetic variances for longissimus muscle area were 76 and 77% larger in bulls at 12 and 14 mo than the corresponding estimates for heifers. Heritability estimates for longissimus muscle area were 0.61 and 0.52 in bulls and 0.49 and 0.47 in heifers at 12 and 14 mo, respectively. The genetic correlations of longissimus muscle area of bulls vs heifers were 0.61 and 0.84 at 12 and 14 mo, respectively. Genetic correlations of longissimus muscle area measured in steer carcasses were 0.71 and 0.67 with the longissimus muscle areas in bulls and heifers at 12 mo and 0.73 and 0.79 at 14 mo. Heritability estimates for fat depth were 0.50 and 0.35 in bulls and 0.44 and 0.49 in heifers at 12 and 14 mo, respectively. The genetic correlation of fat depth in bulls vs heifers at 12 mo was 0.65 and was 0.49 at 14 mo. Genetic correlations of fat depth measured in bulls at 12 and 14 mo with fat depth measured in steers at slaughter were 0.23 and 0.21, and the corresponding correlations of between heifers and steers were 0.66 and 0.86, respectively. Live weights at 12 and 14 mo were genetically equivalent (r(g) = 0.98). Genetic correlations between live weights of bulls and heifers with hot carcass weight of the steers were also high (r(g) > 0.80). Longissimus muscle area measured using RTU was positively correlated with carcass measures of longissimus muscle area, estimated percentage lean yield, and percentage lean in a 7-rib section from steers. Measures of backfat obtained using RTU were positively correlated with fat depth and dissectable seam fat from the 7-rib section of steer carcasses. Genetic correlations between measures of backfat obtained using RTU and marbling were negative but low. These results indicate that longissimus muscle area and backfat may be under sufficiently different genetic control in bulls vs heifers to warrant being treated as separate traits in genetic evaluation models. Further, traits measured using RTU in potential replacement bulls and heifers at 12 and 14 mo of age may be considered different from the corresponding carcass traits of steers.  相似文献   

17.
The primary objective was to estimate breed, heterosis, and recombination effects on growth and carcass traits of two different four-breed composite populations of pigs. Experiment 1 (Exp. 1) included purebred and crossbred pigs originating from Yorkshire, Landrace, Large White, and Chester White breeds, and Experiment 2 (Exp. 2) included pigs from Duroc, Hampshire, Pietrain, and Spot breeds. Data were recorded on purebred pigs, two-breed cross pigs, and pigs from generations F1 through F6, where F1 pigs were the first generation of a four-breed cross. Pig weights were recorded at birth and at 14, 28, 56, 70, and 154 d of age. Average daily gain was calculated for intervals between weights, and ultrasonic backfat measurements (A-mode) were taken at 154 d of age. Feed intake was measured between 70 and 154 d of age on mixed pens of boars and barrows. Carcass backfat, length, and loin muscle area were measured on barrows at slaughter. Mixed-model analyses were done separately by experiment, fitting an animal model. Fixed effects included farrowing group and sex for growth traits and farrowing group for carcass traits. For ADFI, a weighted mixed-model analysis was done fitting farrowing group as a fixed effect, sire nested within farrowing group as a random effect, and weighting each observation by the number of pigs in each pen. To test feed efficiency, a second analysis of ADFI was done adding ADG as a covariate in the previous model. Included as covariates in all models were direct, maternal, and maternal grandam breed effects, direct and maternal heterosis effects, and a direct recombination effect. Recombination is the breakup of additive x additive epistatic effects present in purebreds during gamete formation by crossbred parents. Effects of direct heterosis significantly increased weights at birth, 14, 56, 70, and 154 d of age in Exp. 1. Effects of direct heterosis significantly increased ADG from birth to 14, 28 to 56, and 70 to 154 d of age in Exp. 1. In Exp. 2, effect of direct heterosis significantly increased weights and ADG at all ages. In Exp. 1, recombination significantly reduced loin muscle area. In Exp. 2, recombination significantly increased weights at birth, 14, 28, and 56 d, ADFI from 70 to 154 d, and ADFI adjusted for ADG. The correlation between maternal heterosis and recombination effects for all traits in Exp. 1 and Exp. 2 was approximately -0.90. Maternal heterosis and recombination effects were estimable, but greatly confounded.  相似文献   

18.
The aim of this study was to investigate whether there is a relationship of young boar testes size with semen traits and with productive traits. The dimensions (length, width and volume) of each testis and semen traits (semen volume, percentage of sperm with progressive motility, sperm concentration, total number of sperm in semen, percentage of sperm with normal acrosome, percentage of sperm with major and minor morphological defects, osmotic resistance test value and activity of aspartate aminotransferase in seminal plasma) were determined on 120 young boars aged 6 months. At 180 day of age, the boars backfat thickness and leanness (by ultrasonic apparatus) and body weight were also measured. The average daily gain was determined in the period from 70 to 180 days of age of the boars. The results showed that the sperm concentration, total number of sperm in semen and percentage of progressive motile sperm were a significantly positively correlated with width and volume of the left (p ≤ 0.01) and right testis (p ≤ 0.05) and with total volume of both testes (p ≤ 0.01). But the highest values of correlation coefficients were found between the width of the left testis and sperm concentration, total number of sperm in semen and percentage of progressive motile sperm. A correlations of dimensions (length and width) and volume of testes with other semen traits were very low and statistically non‐significant. The volume of testes (left and right testis and total testes) was significantly positively correlated with body weight at 180 days of age and daily gain (p ≤ 0.01), but lower correlation coefficient was between left testis and daily gain (p ≤ 0.05), whereas correlations were low and non‐significant with leanness and backfat thickness.  相似文献   

19.
Genetic parameters for prolificacy traits for Columbia (COLU), Polypay (POLY), Rambouillet (RAMB), and Targhee (TARG) breeds of sheep were estimated with REML using animal models. Traits were number of live births (LAB), litter size at birth (LSB) and weaning (LSW), and litter weight weaned (LWW). Numbers of observations ranged from 5,140 to 7,095 for prolificacy traits and from 5,101 to 8,973 for litter weight weaned for the four breeds. For single-trait analyses, ewes were classified as young (1 yr old), middle-aged (2 and 3 yr old), or older (> 3 yr old). After single-trait analyses, three-trait analyses were done for each characteristic with traits defined by age class. Generally, heritability estimates from single-trait analyses were low and ranged from .01 to .17 for LAB and LSB and from .00 to .10 for LSW. Heritability estimates obtained for LWW ranged from low to moderate (.00 to .25) and were less for older ewes. Heritability estimates from the three-trait analyses were generally similar to estimates from single-trait analyses. Heritabilities for LAB and LSB were similar, and, for three-trait analyses, they ranged across age groups from .07 to .13 for COLU, .13 to .16 for POLY, .10 to .16 for RAMB, and .01 to .16 for TARG. Estimates for LSW from three-trait analyses ranged from .07 to .12 for COLU, .04 to .09 for POLY, .01 to .11 for RAMB, and .03 to .11 for TARG. For LWW, heritabilities ranged from .00 to .21 for COLU, .05 to .08 for POLY, .12 to .15 for RAMB, and .18 to .29 for TARG. Genetic correlations for LAB, LSB and LSW among age-defined traits ranged from .25 to 1.00. Genetic correlations for LAB and LSB between young and middle and between young and older age classes were less than .80 in COLU, POLY, and RAMB breeds. Only genetic correlations between middle and older age classes for these breeds were greater than .80. For TARG, genetic correlations among all age classes were greater than .80 (.88 to 1.00) for those traits. All genetic correlations among ages for LSW were greater than .80 for POLY and TARG. For RAMB, only the correlation between young and older age classes for LSW was less than .80 (.45). None was greater than .80 for COLU. For LWW, genetic correlations among all age classes in POLY and RAMB were greater than .80 (.82 to 1.00). For COLU, genetic correlation between young and middle was low (.07), between young and older was high (.88), and between middle and older classes was moderately high (.54). For TARG, genetic correlations were .49, .65, and .98 for young-middle, young-older, and middle-older age classes, respectively. Results indicate that more progress could be made in selection programs for prolificacy traits in some sheep breeds by considering age of ewe as a part of the trait rather than by simply adjusting for ages of ewes.  相似文献   

20.
Testicular tissue and blood samples (V. spermatica interna) were taken from 32 boars during castration. The animals were different age groups. Against this background, studies were conducted into the correlations between testicular and plasma testosterone, on the one hand, and the amount of interstitial cells of Leydig in testicular tissue as well as the latters' cell nuclei volumes, on the other. The results seemed to support the conclusion that any age-dependent increase of testicular and plasma testosterone concentrations was caused unambigously by an absolute increase in volume of androgenic testicular tissue, in concomitance with testicular growth, in other words, by rise in the total number of interstitial cells of Leydig.  相似文献   

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