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1.
Reciprocal cross differences have been reported for growth rate and carcass traits in F1 pigs with the Duroc (D) as a parent breed. Such differences are synonymous with maternal effects if effects of sex linkage and genomic imprinting are negligible. In the present study, transfer of embryos (ET) to paternal breed recipients partitioned effects occurring at or before fertilization from postfertilization effects for growth and carcass traits in F1 D-Landrace (L) pigs. Fifteen boars sired 115 F1 litters, 49 produced by ET. Growth rate of 349 barrows and 361 gilts and carcass measurements on 256 barrows and 159 gilts were analyzed assuming mixed linear models with animal and litter as random effects. Contrasts among genotype (D x L, L x D)- treatment (ET, non-ET) means were tested. Reciprocal cross differences were not detected for growth rate or for carcass weight, length, average backfat thickness, estimated carcass lean, or lean per day of age. Reciprocal cross differences for 10th rib backfat thickness (BF) and longissimus muscle area (LMA) were detected only in barrows. The sexual dichotomy for reciprocal cross differences followed expectations for a Y-linked gene(s), consistent with the fact that reciprocal D-L crossbred barrows exhibited a paternal effect, with responses more like the sire breed than the dam breed. Barrows that were non-ET from D sires and L dams had 3.9 cm2 larger LMA and 5.8 mm less BF than barrows from L sires and D dams (P less than .001). Barrows from ET sired by D boars had 3.8 cm2 larger LMA than did barrows from ET sired by L boars (P less than .001), although no difference was detected for BF. Barrows sired by D boars reared in a D postfertilization environment (ET) had 6.2 cm2 greater LMA and 4.1 mm less BF (P less than .05) than barrows sired by L boars gestated and reared by D dams (non-ET). Barrows sired by D boars reared by L dams (non-ET) had 1.5 cm2 greater LMA and 2.3 mm less BF (P greater than .10) than barrows sired by L boars reared by L dams (ET). In conclusion, reciprocal cross differences detected for BF and LMA in barrows were established before or at fertilization and seemed to be Y-linked.  相似文献   

2.
Knowledge of breed effects on carcass and pork quality traits is required to develop commercial crossbreeding programs that emphasize product quality. A 2 x 2 diallel mating system involving Landrace and Duroc pigs was used to estimate individual heterosis, direct breed effects and reciprocal cross differences for post-weaning growth, real-time ultrasound, carcass, and pork quality traits. Data from 5,649 pigs and 960 carcasses representing 65 and 49 sires, respectively, were analyzed assuming animal models. Duroc-sired pigs had 2.1 cm shorter carcasses with 7.3 mm less 10th rib backfat (BF), 4.4 cm2 larger longissimus muscle area (LMA), yielded 2.1 kg more estimated fat standardized lean (FSL), gained 16.5 g more estimated lean per day of age (LDOA), and had 1.0% less water (PWAT) and 1.9% more intramuscular fat (IMF) in the longissimus muscle than did Landrace-sired pigs (P less than .01), adjusted to an off-farm live weight of 111 kg. Reciprocal cross differences were detected for BF, LMA, FSL, LDOA and for subjective marbling, firmness, and muscling scores (P less than .01). Durocsired F1 barrows had 6.3 mm less BF and 5.9 cm2 larger LMA, yielded 3.2 kg more FSL, gained 22.3 g more LDOA, and had less marbling in the longissimus muscle and heavier ham muscling than reciprocal cross barrows. Heterosis estimates (P less than .05) were 27.6 g/d (3.2%) for ADG, -5.8 d (-3.6%) for off-test age, 2.7 cm (3.4%) for carcass length, 1.5 kg (7.2%) for FSL, 14.7 g (5.7%) for LDOA, -.07 (-3.6%) for muscle color, -.5% (-13.2%) for IMF, and .3% (.3%) for PWAT. Breed effects were not detected (P greater than .10) for muscle pH, cooking loss, shear value, and water-holding capacity or for eating quality traits. Reciprocal cross differences suggest an advantage in using the Duroc as a terminal sire, but improved carcass composition and higher intramuscular fat did not seem to affect eating quality traits.  相似文献   

3.
A study was conducted to evaluate differences in performance and in carcass composition and tissue deposition rates between purebred Duroc pigs sired by boars currently available and those sired by boars from the mid-1980s. Two lines were developed by randomly allocating littermate and half-sib pairs of females to matings by current time period (CTP) or old time period (OTP) boars. Pigs from 2 replications were placed on test at a group mean BW of 63.5 kg. Serial ultrasonic measurements of the 10th-rib LM area (LMA), off-midline backfat (BF10), and intramuscular fat percentage (IMF) were collected every 2 wk in the first replication and used to assess deposition rate differences. Off-test ultrasonic LMA, BF10, and IMF measurements from a total of 557 pigs from 23 CTP sires and 232 pigs from 15 OTP sires across 2 replications and at a mean BW of 109 kg were evaluated. All available barrows and randomly selected gilts (n = 277) were sent to a commercial abattoir, and carcass measurements of 10th-rib backfat, last-rib backfat, last lumbar backfat, and LMA were collected. Analysis of serial backfat measurements revealed a linear relationship between back-fat and BW between 73 and 118 kg for pigs from both time periods. Pigs sired by OTP boars deposited more backfat (P < 0.05) at a faster rate than pigs sired by CTP boars over the entire test period. A curvilinear cumulative tissue deposition pattern was revealed for ultrasonically estimated LMA and IMF within both time periods. Significant linear and quadratic regression coefficient differences between lines indicated that pigs sired by CTP boars deposited more LMA and less IMF per kilogram of BW gain than pigs sired by OTP boars. Pigs sired by CTP boars had more LMA and less BF10 (P < 0.05), whereas pigs sired by OTP boars had more IMF (P = 0.04). Carcass evaluation revealed more (P < 0.01) carcass measurements of LMA and less (P < 0.05) carcass measurements of 10th-rib backfat, carcass measurements of last-rib backfat, and carcass measurements of last lumbar backfat for pigs sired by CTP boars. No difference (P > 0.05) between the time periods was found for ADG over the entire test period. Results from this study illustrate that significant progress in carcass composition has been realized within the Duroc breed since the mid-1980s. The long-term selection response in carcass leanness has also resulted in changes in deposition rates of correlated traits such as LMA and IMF.  相似文献   

4.
The objective of this study was to investigate the importance of maternal genetic effects on postweaning performance traits of Yorkshire, Landrace, Duroc, and Hampshire breeds of swine. Data consisted of performance test records collected in a commercial swine operation from 1992 to 1999. Boars from 60% of the litters were culled at weaning based on a combination of maternal and performance indexes that differed by breed. Remaining boars and all females were grown to 100 d of age. At this time all pigs were weighed (WT100) and selected for testing using recalculated breed-specific indexes (n = 15,594, 55,497, 12,267, and 9,782 for Landrace, Yorkshire, Duroc, and Hampshire, respectively). All pigs were weighed at the end of the 77-d test, and backfat (BF) and loin eye area (LEA) were measured over the 12th rib by ultrasound. Average daily feed intake was calculated for boars, and ADG was calculated for all animals. Genetic parameters were estimated for each breed and trait using multiple-trait DFREML procedures. Fixed effects were contemporary groups and either initial or final test age as a covariate. Four models were examined. Model 1 included only the additive genetic effect of the animal. Model 2 added the common litter environmental effect; Model 3 added the maternal genetic value assumed to be uncorrelated with additive genetic effects. Model 4 was the same as Model 3 with additive and maternal genetic effects assumed to be correlated. All models were two-trait models with WT100 as the second trait. Ratios of likelihoods were used to compare models. Maternal effects were important (P < 0.05) for WT100, ADG, ADFI, LEA, and BF in Landrace; for WT100, ADG, LEA, and BF in Yorkshire; for WT100 and ADG in Duroc, and for WT100 in Hampshire. Estimates of heritabilities for direct additive effects using the appropriate model for ADG, ADFI, LEA, and BF were 0.28, 0.34, 0.48, and 0.63 for Landrace; 0.26, 0.31, 0.39, and 0.65 for Yorkshire; 0.14, 0.20, 0.26, and 0.35 for Duroc; and 0.17, 0.23, 0.25, and 0.31 for Hampshire, respectively. Heritability estimates for maternal genetic effects for ADG, ADFI, LEA, and BF were 0.02, 0.05, 0.06, and 0.07 for Landrace and 0.02, 0, 0.04, and 0.06 for Yorkshire, respectively. They were zero for all traits except ADG (0.03) in Duroc and for all traits in Hampshire. Maternal effects may need to be considered in genetic evaluation of performance traits in some breeds of swine.  相似文献   

5.
Accurate evaluations of growth and composition traits enable better management decisions regarding genetic merit, feeding, and marketing. Sires from Duroc and Pietrain populations were used to produce crossbred pigs, which were evaluated for growth and composition traits. All parents were normal for the ryanodine receptor gene. Boars from each breed were mated to either Yorkshire or F1 Yorkshire-Landrace females with 307 offspring evaluated from birth through 26 wk of age. No significant differences between sire breeds were seen for pig BW from birth through 10 wk of age. Body weight, 10th rib backfat (BF10), last rib backfat (LRF), and loin muscle area (LMA) were serially measured at 10, 13, 16, 19, 22, 24, and 26 wk of age. At 26 wk of age, Duroc-sired progeny were heavier (143.4 vs. 132.7 kg, P < 0.001), had more BF10 (27.1 vs. 23.7 mm, P < 0.001) and LRF (21.2 vs. 19.2 mm, P < 0.001), but had similar LMA (46.4 vs. 47.1 cm2) compared with Pietrain-sired progeny. Mean feed efficiency did not differ between breed of sire in any period of the study. Duroc progeny had a greater ADG (980.1 vs. 892.3 g/d, P < 0.001) from 10 to 26 wk of age than Pietrain-sired pigs. Composition traits of fat-free total lean (FFTOLN), total fat tissue (TOFAT), empty body protein (EBPRO), and empty body lipid (EBLIPID) were calculated. Random regression animal models with polynomial regression on week on-test were fitted to BW, BF10, LRF, LMA, FFTOLN, TOFAT, EBPRO, and EBLIPID from 10 to 26 wk of age. Duroc-sired barrows tended to grow faster but with more fat tissue, and Pietrain-sired gilts were slower growing but leaner, whereas Duroc-sired gilts and Pietrain-sired barrows were intermediate for growth and backfat measures. Serial heritability estimates generally increased from 10 to 26 wk of age with ranges as follows: BW (0.05 to 0.39), BF10 (0.13 to 0.76), LRF (0.11 to 0.79), LMA (0.05 to 0.73), FFTOLN (0.07 to 0.16), TOFAT (0.19 to 0.45), EBPRO (0.02 to 0.55), and EBLIPID (0.12 to 0.60). Pigs sired by Duroc and Pietrain boars had similar lean tissue growth but achieved it through different mechanisms.  相似文献   

6.
Analyses of variance were computed for records on growth and body composition traits made in 1983 by 255 boars and gilts in selected and control lines of Durocs and Yorkshires and their reciprocal crossbreds. Previous selection over a period of several generations was mainly on an index of sow productivity including preweaning litter sizes and weight. Animals in the select lines were selected for high index values; animals in the control lines were selected to average near the mean index values of that year and line. Breeding animals in all four lines during that period were basically randomly selected with regard to growth rate or body composition traits. The same boars sired both purebred and crossbred litters in 1983. Traits analyzed were average daily gain (ADG) during a standard test period from 56 d of age to 90.7 kg and average backfat thickness (ABF) and longissimus muscle area (LMA) from ultrasonic scans at 90.7 kg. Crossbred pigs had greater (P less than .01) ADG than purebred pigs, but did not differ (P greater than .05) in ABF or LMA. Heterosis was 8.2% for ADG. Crossbreds with Yorkshire dams had thinner (P less than .01) ABF and larger (P less than .01) LMA than crossbreds with Duroc dams. Boars had greater (P less than .05) ADG, thinner (P less than .01) ABF and smaller (P less than .01) LMA than gilts. Correlations between 38 half-sib family averages of purebred and crossbred pigs of the same sex and the same sires were .07, .37 and .24 for ADG, ABF and LMA, respectively. Implications of the above and additional findings for swine breeding strategies are discussed.  相似文献   

7.
Genetic parameters and trends in the average daily gain (ADG), backfat thickness (BF), loin muscle area (LMA), lean percentage (LP), and age at 90 kg (D90) were estimated for populations of Landrace and Yorkshire pigs. Additionally, the correlations between these production traits and litter traits were estimated. Litter traits included total born (TB) and number born alive (NBA). The data used for this study were obtained from eight farms during 1999 to 2016. Analyses were carried out with a multivariate animal model to estimate genetic parameters for production traits while bivariate analyses were performed to estimate the correlations between production and litter traits. The heritability estimates were 0.52 and 0.43 for ADG; 0.54 and 0.45 for BF; 0.25 and 0.26 for LMA; 0.54 and 0.48 for LP; and 0.56 and 0.46 for D90 in the Landrace and Yorkshire breeds, respectively. The ADG and D90 showed low genetic correlation with BF and LP. The LMA had ?0.40, ?0.32, 0.49, and 0.39 genetic correlations with ADG, BF, LP, and D90, respectively. Genetic correlations between production and litter traits were generally low, except for the correlations between LMA and TB (?0.23) in Landrace and ADG and TB (?0.16), ADG and NBA (?0.18), D90 and TB (0.19), and D90 and NBA (0.20) in Yorkshire. Genetic trends in production traits were all favorable except for LMA.  相似文献   

8.
The objective of this study was to estimate heritability for body length (LEN) at the end of performance testing and to estimate genetic correlations with backfat (BF) thickness and loin muscle area (LMA) in Landrace, Yorkshire, Duroc, and Hampshire breeds of swine. Also examined were two measures of body density involving body length and weight and their relationships to backfat and loin muscle area. Data consisted of performance test records collected in a commercial swine operation from 1992 to 1999. Boars from 60% of the litters were culled at weaning based on a maternal breeding value of the dam. Remaining boars and all females were grown to 100 d of age (15,594, 55,497, 12,267, and 9,782 Landrace, Yorkshire, Duroc, and Hampshire pigs, respectively). At this time, all pigs were weighed (WT100) and selected for performance testing based on a combination of maternal and performance indexes, which differed by breed. All pigs were weighed at the end of the 77 d performance test (WT177) when BF, LMA, and LEN were measured. Two measures of body density involving length were calculated: Body mass index (BMI) = WT177/LEN2 and body density (DENSITY) = WT177/LEN. For each breed, genetic parameters were estimated using an animal model with random litter effects and multiple-trait REML procedures. A series of three-trait models including WT100 and combinations of two other traits in each analysis was conducted. Fixed effects included contemporary group and age as a covariate. Average estimates of heritability were 0.16 to 0.32 for LEN (unadjusted for WT177), 0.12 to 0.26 for LEN (adjusted for WT177), 0.23 to 0.33 for DENSITY, and 0.16 to 0.25 for BMI. Genetic correlations between LEN and LMA were low. Genetic correlations between LEN (unadjusted for WT177) and BF were 0.10 to 0.41. Adjusting LEN for WT177 gave correlations of 0.11 for Landrace and Hampshire and negative correlations (-0.06 and -0.19, respectively) for Yorkshire and Duroc. Genetic correlations between LMA and DENSITY and between LMA and BMI were comparable and ranged from 0.44 to 0.54. Genetic correlations between BF and DENSITY were slightly higher (0.53 to 0.68) than those between BF and BMI (0.37 to 0.67). In these data, not much relationship between BF and body length at a constant weight and age was found. There was a negative relationship between LMA and LEN at a constant weight and age, implying that longer pigs had smaller LMA.  相似文献   

9.
Residual feed intake (RFI) is a measure of feed efficiency defined as the difference between the observed feed intake and that predicted from the average requirements for growth and maintenance. The objective of this study was to evaluate the response in a selection experiment consisting of a line selected for low RFI and a random control line and to estimate the genetic parameters for RFI and related production and carcass traits. Beginning with random allocation of purebred Yorkshire littermates, in each generation, electronically measured ADFI, ADG, and ultrasound backfat (BF) were evaluated during a approximately 40- to approximately 115-kg of BW test period on approximately 90 boars from first parity and approximately 90 gilts from second parity sows of the low RFI line. After evaluation of first parity boars, approximately 12 boars and approximately 70 gilts from the low RFI line were selected to produce approximately 50 litters for the next generation. Approximately 30 control line litters were produced by random selection and mating. Selection was on EBV for RFI from an animal model analysis of ADFI, with on-test group and sex (fixed), pen within group and litter (random), and covariates for interactions of on- and off-test BW, on-test age, ADG, and BF with generations. The RFI explained 34% of phenotypic variation in ADFI. After 4 generations of selection, estimates of heritability for RFI, ADFI, ADG, feed efficiency (FE, which is the reciprocal of the feed conversion ratio and equals ADG/ ADFI), and ultrasound-predicted BF, LM area (LMA), and intramuscular fat (IMF) were 0.29, 0.51, 0.42, 0.17, 0.68, 0.57, and 0.28, respectively; predicted responses based on average EBV in the low RFI line were -114, -202, and -39 g/d for RFI (= 0.9 phenotypic SD), ADFI (0.9 SD), and ADG (0.4 SD), respectively, and 1.56% for FE (0.5 SD), -0.37 mm for BF (0.1 SD), 0.35 cm(2) for LMA (0.1 SD), and -0.10% for IMF (0.3 SD). Direct phenotypic comparison of the low RFI and control lines based on 92 low RFI and 76 control gilts from the second parity of generation 4 showed that selection had significantly decreased RFI by 96 g/d (P = 0.002) and ADFI by 165 g/d (P < 0.0001). The low RFI line also had 33 g/d lower ADG (P = 0.022), 1.36% greater FE (P = 0.09), and 1.99 mm less BF (P = 0.013). There was not a significant difference in LMA and other carcass traits, including subjective marbling score, despite a large observed difference in ultrasound-predicted IMF (-1.05% with P < 0.0001). In conclusion, RFI is a heritable trait, and selection for low RFI has significantly decreased the feed required for a given rate of growth and backfat.  相似文献   

10.
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 C and 156 F1 gilts from I and C dams mated with Danbred NA Landrace (L) sires, were evaluated. Direct genetic effects of I and C did not differ for backfat (BF) at 88.2 kg or days to 88.2 kg; however, I pigs had 1.58 cm2 smaller LM area than did C pigs (P < 0.05). Averaged over crosses, F1 gilts had 0.34 cm less BF, 4.29 cm2 greater LM area, and 31 d less to 88.2 kg than did pure line gilts (P < 0.05). In Exp 2, barrows and gilts were individually penned for feed intake recording from 27 to 113 kg and slaughtered. A total of 43 I and C pigs, 77 F1 pigs produced from pure line females mated with either L or Danbred NA 3/4 Duroc, 1/4 Hampshire boars (T), and 76 three-way cross pigs produced from F1 females mated with T boars were used. Direct genetic effects of I and C did not differ for ADFI, ADG, G:F, days to 113 kg, BF, LM area, ultimate pH of the LM, LM Minolta L* score, or percentage of carcass lean. Interactions of line effects with crossing system were significant only for days to 113 kg. Pure line I pigs took 4.58+/-4.00 d more to reach 113 kg than did C pigs, whereas I cross F1 pigs reached 113 kg in 6.70+/-3.95 d less than C cross F1 pigs. Three-way cross and F1 pigs did not differ significantly for most traits, but the average crossbred pig consumed more feed (0.23+/-0.04 kg/d), gained more BW per unit of feed consumed (0.052+/-0.005 kg/kg), grew faster (0.20+/-0.016 kg/d), had less BF (-0.89+/-0.089 cm), greater LM area (5.74+/-0.926 cm2), more lean (6.21+/-0.90%), and higher L* score (5.27+/-1.377) than the average pure line pig did (P < 0.05). Nineteen generations of selection for increased litter size produced few correlated responses in growth and carcass traits, indicating these traits are largely genetically independent of litter size, ovulation rate, and embryonic survival.  相似文献   

11.
A replicated factorial experiment using 183 individually fed crossbred barrows was conducted. Pigs were fed an 18.5% CP (.95% lysine) diet with 3,594 kcal of ME/kg. The effects of five genotypes (GT): 1) Hampshire (H) x (H x Duroc [D]), 2) synthetic terminal sire line, 3) (H x D) x (Landrace [L] x [Yorkshire (Y) x D]), 4) L x (Y x D), and 5) Y x L; two levels of ractopamine (RAC) treatment: 0 and 20 ppm; and three treatment weight periods (WT): 1) 59 to 100, 2) 73 to 114, and 3) 86 to 127 kg live weight on growth performance and carcass traits were evaluated. Ractopamine increased (P less than .0001) amount (FSL) and percentage (PFSL) of carcass lean standardized to 10% fat content, loin eye area (LEA), and dressing percentage (PDRES) and reduced (P less than .01) amount (DF) and percentage (PDF) of dissected fat. Magnitudes of RAC effects were smaller than those reported by other researchers. Effects of GT and WT on all growth and carcass traits were highly significant (P less than .001) except for those of WT on ADG (P less than .05) and GT on average feed intake (AFI) and backfat thickness at the last rib (BFLR; P less than .05). Genotype 3 performed better for most economically important traits than did GT 1 and 4, suggesting that heterosis existed in GT 3, which essentially was obtained by crossing GT 1 and 4. Among the three treatment periods, WT 2 had the highest ADG. As BW increased from WT 1 to 3, AFI and AFI/ADG ratio (FCR) increased and lean percentage decreased.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

12.
Purebred and two-breed cross (F1) boars were mated to F1 females to produce all possible three- and four-breed cross pigs involving the Duroc, Yorkshire, Landrace and Spotted breeds. Individual postweaning average daily gain (ADG), age at 100 kg (AGE) and probed backfat thickness at 100 kg (BF) data were collected on 3,456 pigs. A total of 213 pens with an average of 15.58 pigs per pen was evaluated for postweaning feed-to-gain ratio (F/G) and average daily feed consumption (ADF). Genotype X environment interactions, specifically breed X year-season farrowed and breed X parity (for ADG), were found to be highly significant. Certain results, however, were reasonably consistent across environments. Duroc-sired pigs grew more efficiently than other sire breed groups (3.11 vs 3.21 F/G), although there were no significant differences in ADF between sire groups. Duroc-sired pigs had less BF than other three-breed cross pigs, based upon within breed of dam comparisons, suggesting differences in composition between the more efficient Duroc-sired pigs and other breed groups. Landrace-sired pigs were fatter than other sire groups. No real differences between crossbred-sired pigs and the average of contemporary pure-bred-sired pigs were apparent for F/G, ADF, ADG, AGE, or BF. Assuming paternal heterosis to be zero, these results suggested recombination effects to be negligible for postweaning performance traits. Apart from via direct genetic effects, mating crossbred rather than purebred boars to females of different breeding should have little or no impact on feedlot performance of offspring produced.  相似文献   

13.
A 2-yr study compared progeny performance of high (HI) and low (LI) indexing central test station boars purchased in Iowa, Missouri, Nebraska and Oklahoma. Boars were evaluated for a National Swine Improvement Federation index recommended for central test stations. The 1st yr 22 Hampshire boars were mated to three- and four-breed Duroc, Yorkshire, Landrace and Spotted cross gilts. A disease outbreak the first farrowing season caused severe death loss and reduced performance. From 198 litters, 826 pigs completed their gain test. The 2nd yr 23 Duroc boars were mated randomly to gilts produced the previous year. From 181 litters, 1,070 pigs completed their gain test. No differences existed for postweaning average daily gain (ADG) and probe backfat thickness (PBF); however, progeny sired by HI Hampshire boars were an average of 5.66 units better for the index (I) compared with progeny of LI Hampshire boars. Gilt progeny of HI Duroc boars were .03 kg, .79 mm and 3.93 units greater for ADG, PBF and I, respectively, than LI Duroc-sired gilts. Barrow progeny of LI Duroc boars gained .01 kg/d faster, had .59 mm more PBF and were no different for I than barrows sired by HI Duroc boars. Maternal grandsire effects were important for Duroc-sired pigs, with gilts of HI maternal grandsires having .01 kg faster ADG, yet barrows of HI maternal grandsires had .02 kg slower ADG as compared with gilts and barrows having LI maternal grandsires, respectively.  相似文献   

14.
An experiment with crossbred swine was conducted over six generations of selection based on an index (Index) of average daily gain in weight (ADG) in a test period from 56 d of age to 91 kg gross weight and average backfat thickness (ABF) measured from ultrasonic scans at 91 kg. Test pigs of the high protein select (HS) and control (HC) lines were fed a 24% crude protein (CP) diet and pigs of the low protein select (LS) and control (LC) lines were fed a 12% CP diet during the test period. The extent of genetic (selection line) x environmental (dietary) interaction effects was determined based on feeding closely related boars and gilts from both the HS and LS lines on both diets. Tests were conducted in 1986 and 1987 with progeny of the fifth and sixth generations of selection. Records for 472 pigs sired by 37 boars and out of 101 dams were analyzed for effects of selection and diets on AGE of pig at 91 kg, ADG, ABF, LMA (longissimus muscle area at the last rib) and Index. Statistically significant interactions effects of line x diet were noted (P less than .01) for AGE, ADG and Index, traits with low to moderate heritabilities (h2). For ABF and LMA, body composition traits with moderate or higher h2, interaction effects of line x diet were near zero. These results suggest that for best all-around future performance, traits such as AGE and ADG, selection probably should be practiced under dietary conditions under which future populations will be produced. For body composition traits such as ABF and LMA, selection probably would be more effective if pigs were fed a more enriched protein diet. However, as a practical matter, to more rapidly improve the genetic merit of the swine population, both the central station and on-the-farm testing programs should be conducted under standard commercial production systems.  相似文献   

15.
Hampshire and Landrace sows and crossbreds of the two breeds were used to determine heterosis and recombination effects for milk production, milk composition, and litter traits at birth and d 21. Twelve mating types were represented in this study: two purebred, two F1, two F2, two F3, and four backcross. Information was gathered on a total of 358 litters over four farrowing seasons. Milk production was measured at d 10 and 20 of litter age according to the weigh-suckle-weigh procedure. Milk samples were collected at d 10 and 20 of litter age and evaluated for percentages of fat (PCFA), protein (PCPR), lactose (PCLA), and solids-not-fat (PCSN). The model used to evaluate litter traits at birth included main effects of mating type, parity, and farrowing season. The model used for milk production and milk composition traits included these main effects and number of pigs nursed as a covariate. Estimates of maternal genetic effects showed that Landrace females were superior to Hampshire females for number born (NB), number born alive (NBA), litter birth weight (LBW), adjusted 21-d litter weight (ALW), and milk production at d 10 of litter age (WT10). Hampshires were superior to Landrace for PCPR at d 10 of litter age and PCSN at d 10 and 20 of litter age. Heterosis effects were significant (P less than .05) for NBA (.97) and LBW (1.46 kg). Maternal heterosis effects were significant for LBW (3.94 kg; P less than .01). Epistatic recombination losses in the offspring were significant for LBW (6.80 kg; P less than .05). Differences in maternal performance of reciprocal F1 dams were generally not significant. Heterosis and recombination effects were not significant for milk production or milk composition.  相似文献   

16.
Knowledge of the genetic control of pork quality traits and relationships among pork quality, growth, and carcass characteristics is required for American swine populations. Data from a 2 x 2 diallel mating system involving Landrace and Duroc pigs were used to estimate heritabilities and genetic correlations among growth (ADG), real-time ultrasonic (US) measures of backfat thickness (BF) and longissimus muscle area (LMA), carcass characteristics, and various pork quality traits. Data were collected from 5,649 pigs, 960 carcasses, and 792 loin chops representing 65, 49, and 49 sires, respectively. Genetic parameters were estimated by REML assuming animal models. Heritability estimates were moderate to high for ADG, USBF, USLMA, carcass BF, and LMA, percentage of LM lipid (IMF), pork tenderness, and overall acceptability. Estimates were low to moderate for percentage of cooking loss, pH, shear force, percentage of LM water, water-holding capacity (WHC), pork flavor, and juiciness. Genetic correlations between US and carcass measures of BF and LMA indicate that selection based on US data will result in effective improvement in carcass characteristics. Selection for increased LMA and(or) decreased BF using US is, however, expected to result in decreased IMF and WHC, increased percentage of LM water and shear value, and in decreased juiciness, tenderness, and pork flavor. Average daily gain was favorably correlated with IMF and unfavorably correlated with shear force. Selection for increased ADG is expected to improve WHC but to decrease the percentage of LM water, with an associated decrease in juiciness. The results of this study suggest the feasibility of including meat quality in selection objectives to improve product quality. Favorable genetic correlations between IMF and eating quality traits suggest the possible merit of including IMF in the selection objective to improve, or restrict change in, pork eating quality.  相似文献   

17.
Selection in pigs for either fast (line F) or slow (line S) postweaning gain was replicated in spring (SREP) and fall (FREP) farrowing groups. Littermate barrows were sampled from F and S during Generations 2, 3, and 4 of the SREP and Generation 3 of the FREP. Beginning at approximately 35 kg (OTWT), barrows were either allowed ad libitum access to feed (AL) or limited to a standard total feed intake (LIM). Blocks of the line x intake level factorial were removed from test and carcass data collected when the average weight of barrows in the block was approximately 110 kg. Carcass data were also collected on an additional barrow from each litter at OTWT to allow estimation of lean tissue gain per unit of feed consumed (LTFC) of tested barrows. In Generations 3 and 4 of the SREP, F-AL was greater (P less than .01) than S-AL for average daily intake and ADG; carcass backfat was greater (P less than .01) but LTFC tended to be less (P less than .10) for F-AL than for S-AL. When LIM was imposed in the SREP, F barrows gained faster (P less than .05) than S barrows in Generation 4, but across generation the lines did not differ for carcass backfat and LTFC was greater (P less than .01) for F than for S. In the FREP, F-AL was greater (P less than .05) than S-AL for average daily intake and ADG and was less (P less than .05) for LTFC, but F and S did not differ for these traits when LIM was imposed; carcass backfat of F was greater (P less than .01) than that of S by .46 cm under AL and .38 cm under LIM. Most of the response in ADG could be attributed to changes in intake, but results in Generation 4 of the SREP indicated that changes in efficiency had also contributed. Most of the additional intake in F vs S resulted in deposition of fat, probably due in part to the heavier weight of F-AL vs S-AL barrows.  相似文献   

18.
To alleviate the need for daily injection of porcine somatotropin (pST), a sustained-release implant (pSTSR) was devised that continuously delivers a daily dose of 2 mg of pST for 42 d. Ninety-six white composite (Large White x Landrace) finishing barrows (83.6 +/- 1.2 kg BW) were assigned to receive zero or two pSTSR implants (4 mg pST/d) and to consume one of six diets differing in total Lys concentration (0.29, 0.52, 0.75, 0.98, 1.21, or 1.44%, as-fed basis). Diets were formulated to be isocaloric and based on the ideal protein concept. Pigs were housed individually, allowed ad libitum access to feed and water, and slaughtered at 112 kg of BW. The pSTSR affected neither ADG (P = 0.88) nor 10th rib LM area (LMA; P = 0.51), but it decreased (P < 0.01) ADFI, average backfat thickness, 10th rib fat depth, weights of leaf fat and ham fat, improved (P < 0.05) G:F, and increased (P < 0.01) weights of four trimmed lean cuts (T-cuts), and percentages of ham lean and bone. Increasing total Lys increased ADG (quadratic; P < 0.05) and ADFI (linear; P < 0.01). The G:F, plasma urea N concentrations (PUN), and T-cuts were affected by the interaction pSTSR x dietary Lys (P < 0.01). Without pSTSR, the G:F did not differ (P = 0.37) among pigs fed 0.52% and greater total Lys. With pSTSR, the G:F was less (P < 0.05) for pigs fed 0.52% than 0.98 and 1.44% total Lys. Increases in dietary total Lys resulted in increased PUN (P < 0.01), and incremental increases were less in pSTSR-implanted pigs. Maximal yield of T-cuts was at 0.98% dietary total Lys in nonimplanted pigs and 1.21% total Lys in pSTSR-implanted pigs. Estimates of total Lys requirements of pigs without and with pSTSR, respectively, were 0.52 and 0.86% for growth (ADG and G:F) and 0.73 and 0.88% for lean production (LMA and T-cuts). Equivalent apparent ileal digestible Lys requirements of pigs without and with pSTSR, respectively, were 0.44 and 0.68% for growth, and 0.62 and 0.75% for lean production. With ADFI of 3.5 kg daily, an intake of approximately 26.1 g of total daily Lys (0.75%) or 22.4 g of apparent ileal digestible Lys is needed to maximize lean production in finishing barrows receiving 4 mg pST/d via sustained-release implant.  相似文献   

19.
A total of 124 Duroc and 99 Landrace primiparous and multiparous sows were assigned, within breed and contemporary group, to control (N) or 10% added fat (F) diets on d 105 of gestation based on parity and genetic line (control or selected for improved sow productivity), to determine the effects of genetic line and fat addition to the lactation diet on sow and litter performance. Weekly feed intake was not affected (P greater than .10) by genetic line for Duroc and Landrace sows but feed intake was reduced (P = .08) during wk 1 to 4 for Duroc sows and during wk 1 and 4 for Landrace sows (P less than .05) when they were fed diet F compared with diet N. Select (S)-line Duroc and Landrace sows lost more weight during lactation (P less than .01) than did control (C)-line sows. Select-line Landrace sows lost more backfat during lactation (P less than .05) than did C-line sows. Landrace sows lost less weight during lactation (P less than .05) when fed diet F than when fed diet N. The total number of pigs born, born alive, and alive at 21 d and at weaning were higher (P less than .01) for S-line Duroc sows, and litter size at 21 d and at weaning was higher (P less than .01) for S-line Landrace sows than for C-line litters within each breed. Pig survival from birth to weaning was increased (P = .07) for Duroc sows fed diet F but not for Landrace sows.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

20.
The rate of gain, carcass measurements and three muscles were evaluated in 65 crossbred boars representing 13 litters that were allotted at 4 wk of age to slaughter weight and treatment groups as follows: 1) 105 kg, castrated; 2) 105 kg, intact; 3) 118 kg, intact; 4) 132 kg, intact and 5) 145 kg, intact. One barrow and four boars within a litter constituted a replicate and each replicate was penned separately. The growth rate of all boars to 105 kg constituted one group and was compared with the growth rate of barrows to 105 kg live body weight. Average daily gain from 4 wk until 105 kg did not differ significantly between boars and barrows. Growth rate of the boars continued at an increasing rate until they reached 87.3 kg live weight, while maximum daily gain of barrows occurred at 76.3 kg live weight or 11 kg less than that of boars. At 105 kg, boars had 31.3% less 10th rib backfat thickness and 2.9% greater carcass length than barrows, but longissimus muscle area did not differ. Barrows had greater backfat thickness at 105 kg than 145-kg boars. As live weight increased from 105 to 145 kg, carcass length, 10th rib backfat thickness and longissimus area of boars increased (P less than .01) linearly. Fat-free muscle weights of the brachialis (BR), semitendinosus (ST) and longissimus (L) did not differ between boars and barrows at 105 kg. Boars at 105 kg had 1.3 and 1.7% more moisture in the BR and ST, respectively, than barrows. Percentage protein, total intramuscular fat and fiber diameter in the BR, ST and L muscles did not differ between boars and barrows at 105 kg or with increasing live weight in boars. Total RNA increased linearly (P less than .05) in the BR and ST as boars increased in live weight from 105 to 145 kg.  相似文献   

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