Hampshire Boars Research Articles

Responses to 19 generations of litter size selection in the NE Index line. II. Growth and carcass responses estimated in pure line and crossbred litters.

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.

Examination of the relationship between the estrogen receptor gene and reproductive traits in swine12

The relationship between estrogen receptor (ESR) genotype and reproductive traits in a population of Yorkshire, Large White, and crossbred animals was studied. Reproductive tract and litter data were analyzed for associations with ESR genotype, parity, and breed. Forty-six Yorkshire, 31 Large White, and 70 crossbred females from the above population were mated to Hampshire boars and slaughtered at 75 d of gestation. Data collected included ovulation rate, uterine horn length, number of fetuses, fetal weight, uterine weight, number of mummies, fetal sex, fetal placement, fetal survival, and fetal space. Data were analyzed using a model that included the fixed effects of ESR genotype, breed, parity, and all significant two-way interactions. Litter data representing 212 litter records were analyzed in a model that included the fixed effects of ESR genotype of dam, parity, farrowing month, dam breed, sire breed, and all significant two-way interactions. The ESR genotype was significantly associated with the total litter weight of piglets born and total litter weight of piglets born alive. Dams with the AA genotype had significantly (P = 0.04) heavier litters at birth (14.44 ± 0.36 kg) than dams with the BB genotype (13.43 ± 0.47 kg). Ovulation rate was significantly (P < 0.05) different between animals of parity 1 (17.22 ± 0.41) and parity ≥ 3 (19.92 ± 0.85). Significant breed effects were observed for fetal weight, with purebred Large White animals having a greater fetal weight per horn (3,909 ± 114 g) than purebred Yorkshire animals (3,553 ± 92 g). Notable, but nonsignificant, trends with respect to ESR genotype were also observed for number of piglets alive at weaning and total litter weight at weaning. The ESR gene is positively associated with several previously uninvestigated reproductive traits.

Examination of the relationship between the estrogen receptor gene and reproductive traits in swine.

The relationship between estrogen receptor (ESR) genotype and reproductive traits in a population of Yorkshire, Large White, and crossbred animals was studied. Reproductive tract and litter data were analyzed for associations with ESR genotype, parity, and breed. Forty-six Yorkshire, 31 Large White, and 70 crossbred females from the above population were mated to Hampshire boars and slaughtered at 75 d of gestation. Data collected included ovulation rate, uterine horn length, number of fetuses, fetal weight, uterine weight, number of mummies, fetal sex, fetal placement, fetal survival, and fetal space. Data were analyzed using a model that included the fixed effects of ESR genotype, breed, parity, and all significant two-way interactions. Litter data representing 212 litter records were analyzed in a model that included the fixed effects of ESR genotype of dam, parity, farrowing month, dam breed, sire breed, and all significant two-way interactions. The ESR genotype was significantly associated with the total litter weight of piglets born and total litter weight of piglets born alive. Dams with the AA genotype had significantly (P = 0.04) heavier litters at birth (14.44 +/- 0.36 kg) than dams with the BB genotype (13.43 +/- 0.47 kg). Ovulation rate was significantly (P < 0.05) different between animals of parity 1 (17.22 +/- 0.41) and parity > or = 3 (19.92 +/- 0.85). Significant breed effects were observed for fetal weight, with purebred Large White animals having a greater fetal weight per horn (3,909 +/- 114 g) than purebred Yorkshire animals (3,553 +/- 92 g). Notable, but nonsignificant, trends with respect to ESR genotype were also observed for number of piglets alive at weaning and total litter weight at weaning. The ESR gene is positively associated with several previously uninvestigated reproductive traits.

Performance of a Swedish deep-bedded feeder pig production system in Iowa

AbstractAt the Iowa State University Armstrong Research and Demonstration Farm in southwestern Iowa, a Swedish feeder pig production system was studied and demonstrated for 2-1/2 years. The system is based mainly on straw bedding, simple buildings, and intensive management. The system was designed to minimize pig stress and use of subtherapeutic antibiotics in the feed. Gestating and breeding sows were group-housed in a hooped structure with individual feeding stalls. Large round bales of cornstalks were used for bedding. Farrowing, lactation, and nursery phases were housed in a remodeled hog house. Cubicles with rollers and oat straw bedding were used for farrowing. Two groups of Yorkshire × Landrace sows bred to Hampshire boars produced feeder pigs in the system. Conception rates averaged 95%, and litter size averaged 11.3 live pigs/litter. Sows were allowed to select their own bedded farrowing cubicle. Prewean pig mortality, mostly from crushing, was high (29%), occurring primarily in the first 3 days. At 2 weeks of age the cubicles were removed and group lactation occurred. After group lactation the average pig weaning weight was 10.4 kg at 33.9 days of age. At weaning the sows were removed, and the pigs remained in the bedded farrowing/lactation room for 24 additional days. The pigs weighed 24.8 kg at 60 days of age, and overall nursery phase average daily weight gain was 549 g/day. Overall pig health was excellent with no major clinical diseases confirmed. The demonstration exceeded reproductive performance measures of typical small- and mid-sized Iowa farms.

Detection and duration of porcine reproductive and respiratory syndrome virus in semen, serum, peripheral blood mononuclear cells, and tissues from Yorkshire, Hampshire, and Landrace boars.

Because transmission of porcine reproductive and respiratory syndrome virus (PRRSV) can occur through boar semen, it is important to identify persistently infected boars. However, even for boars given the same PRRSV strain and dose, variability in the duration of viral shedding in semen has been observed, suggesting that host factors are involved in PRRSV persistence. To determine whether there are host genetic factors, particularly litter and breed differences related to the persistence of PRRSV, 3 litters from 3 purebred swine breeds were used for this study. It was also determined whether PRRSV could be detected for a longer period of time in serum, semen, or peripheral blood mononuclear cells (PBMC) and if PRRSV could still be detected in tissues after these antemortem specimens were PRRSV negative for a minimum of 2-3 weeks. Three Hampshire, 3 Yorkshire, and 2 Landrace PRRSV-naive boars were obtained and inoculated intranasally with a wild-type PRRSV isolate (SD-23983). All boars within each breed were from the same litter, and litters were within 9 days of age. Serum and PBMC were collected twice weekly from each boar and analyzed for the presence of PRRSV by virus isolation and the polymerase chain reaction (PCR). Serum was also used to obtain virus neutralization titers and enzyme-linked immunosorbent assay S/P values. Semen was collected twice weekly from 7 of 8 boars and analyzed by PCR. After all specimens were PRRSV negative for a minimum of 2-3 weeks, each boar was euthanized, and 21 tissues plus saliva, serum, feces, and urine were collected. All postmortem specimens were evaluated by virus isolation. Specimens that were PRRSV negative by virus isolation were then evaluated by PCR. The mean number of days (+/-SD) for the duration of PRRSV shedding in semen was 51+/-26.9 days, 7.5+/-4.9 days, and 28.3+/-17.5 days for Landrace, Yorkshire, and Hampshire boars, respectively. Because of small sample sizes and large SDs, the differences in duration of PRRSV shedding in semen between breeds were not considered significant. However, the trend suggested that Yorkshire boars were more resistant to PRRSV shedding in semen than were Landrace boars, requiring further investigation using a larger numbers of boars. PRRSV was detected for a longer period in semen than in serum or PBMC in 4 of 7 boars. Viremia could be detected for a longer period in serum than in PBMC in 6 of 8 boars. After a minimum of 2-3 weeks of PRRSV-negative serum, semen, and PBMC, PRRSV could still be detected in the tonsil of 3 of 8 boars by virus isolation, indicating that boars still harbor PRRSV within the tonsil even though antemortem specimens are PRRSV negative.

The influence of ultimate pH and intramuscular fat content on pork tenderness and tenderization.

Intramuscular fat (IMF) and ultimate pH (pHu) influence tenderness, but their roles have not been conclusively determined. Length of storage also affects tenderness and may interact with IMF and pHu. We evaluated the effects of pHu, IMF, and storage time on the tenderness of pork longissimus muscle and determined whether the contribution of the various factors was dependent on genetic line. To obtain variation in IMF, Berkshire (B), Duroc (D) and Hampshire (H) boars were crossed with Yorkshire-Landrace sows. In four trials, a total of 176 pigs were used. To obtain a range in pHu, half of the pigs were deprived of feed before slaughter. Warner-Bratzler shear force (WBS) of each loin was assessed after 2, 7, and 14 d of storage at 0 to 2 degrees C. Warner-Bratzler shear force decreased (P < 0.05) from 4.89 kg at d 2 to 4.16 kg at d 7 to 3.52 kg at d 14. The H pork (n = 62) had a lower (P < 0.05) WBS than the other pork at d 2. After 7 d of storage, this difference had disappeared. Based on glycolytic potential, 30 of the H pigs were carriers of the Rendement Napole (RN) gene. When these pigs were excluded from the analysis, there was no difference in tenderness or tenderization of H, D, and B pork. The correlation between IMF and WBS was -0.11 at d 2, -0.21 at d 7, and -0.19 at d 14. In D pork, the relationship between IMF and WBS was linear, and IMF accounted for 47% of the differences in WBS. In H and B pork, the relationship between IMF and WBS was not significant. For each cross, the relationship between pHu and WBS was different; in D pork it was quadratic, in H pork WBS increased linearly, and in B pork there was no significant relationship between WBS and pHu. The 30 kDa/actin ratio, a measure of myofibrillar degradation, increased (P < 0.05) during storage. Differences in 30 kDa/actin ratio did not explain differences in pork tenderness or tenderization. Further research on determinants and mechanisms of pork tenderness and pork tenderization is needed before production of consistently tender pork will be possible.

The effect of the Halothane and Rendement Napole genes on carcass and meat quality characteristics of pigs.

The objective of this study was to determine the effects of the Halothane (N) and Rendement Napole (RN) genes on carcass and meat quality characteristics in pigs. Halothane and RN carrier (Nn/RN- rn+) Hampshire boars (n = 4) were mated to dams that were homozygous for the normal allele of both genes (NN/rn+ rn+) to produce progeny of four genotypes: 1, NN/rn+ rn+ (n = 31); 2, Nn/rn+ rn+ (n = 27); 3, NN/RN- rn+) (n = 30); and 4, Nn/RN- rn+ (n = 23). A DNA test was used to determine Halothane genotype, and longissimus glycolytic potential was used to predict the RN genotype. Pigs were reared under standard conditions to approximately 120 kg live weight and slaughtered at a commercial plant, and carcass characteristics and meat quality were evaluated. Halothane carriers (Nn/ _ _), in comparison to Halothane normal (NN/_ _) pigs, had shorter carcasses, lower longissimus ultimate pH, higher Minolta L* and b* values, and greater drip loss. Rendement Napole gene carriers (_ _/RN- rn+) had higher L* and b* values and drip and cooking loss and lower longissimus ultimate pH than homozygous recessive animals (_ _/rn+ rn+). There were Halothane x RN genotype interactions (P < 0.05) for subjective color, firmness, and marbling scores, and for shear force. Animals that were normal for both genes (NN/rn+ rn+) had the highest subjective scores for color (2.60, 1.88, 1.85, and 1.95, SE = 0.181, P < 0.05), firmness (2.53, 2.03, 2.10, and 1.89, SE = 0.182, P < 0 .05), and marbling (2.11, 1.44, 1.53, and 1.55, SE = 0.153, P < 0 .05) for genotypes 1, 2, 3, and 4, respectively, suggesting darker, firmer muscle with a higher level of marbling for this genotype. Shear force was highest for Nn/rn+ rn+ animals (3.83, 4.41, 3.79, and 3.70, respectively, SE = 0.172, P < 0.05). Gilts had less s.c. backfat thickness, greater longissimus muscle area, and lower subjective marbling scores than barrows. There was no effect (P > 0.05) of gender on other meat quality traits. This study illustrates the negative effects of the Halothane and RN genes on fresh pork quality and suggests that in combination the detrimental effects of the two genes are additive for ultimate pH, objective color, and water-holding capacity.

Prevalence of Campylobacter spp isolated from the intestinal tract of pigs raised in an integrated swine production system

Objective To enumerate the prevalence of Campylobacter isolates in the intestinal tract of market-weight swine raised in an integrated swine operation in Texas. Sample Population Samples of cecal contents were collected from 595 pigs (mean body weight, 110 kg [242 lb]) at time of slaughter. Pigs were offspring of Yorkshire-Landrace sows and Duroc or Hampshire boars. Pigs originated from 4 farrow-to-finish farms. Procedure During a 9-month period, visits were made to a slaughter plant to remove cecal contents from market-weight hogs. Samples were obtained from 50 pigs/visit from designated farms so that samples were obtained 3 times from pigs of each of 4 farms. Isolation of Campylobacter spp was accomplished by use of enrichment broth and restrictive media, using microaerophilic conditions. Results Campylobacter spp were isolated from 70 to 100% of the pigs, depending on the farm and the date the samples were collected. Campylobacter coli was isolated from 20 to 100% (mean, 60%) of samples, and C jejuni was isolated from 0 to 76% (mean, 31%) of samples. Campylobacter lari was isolated from 2 pigs. Concentrations of C coli or C jejuni ranged from 103 to 107 colony-forming units/g of cecal content. Conclusions and Clinical Relevance Campylobacter coli generally is accepted as a common inhabitant of the intestinal tract of swine. However, analysis of results of this study suggests that a relatively high prevalence of C jejuni may be found in pigs raised on specific farms. (J Am Vet Med Assoc 1999;215:1601–1604)

Pattern of protein retention in growing boars of different breeds, and estimation of maximum protein retention

Protein and energy metabolism in boars of different breeds, 10 each of Hampshire, Duroc and Danish Landrace was measured in balance and respiration experiments by means of indirect calorimetry in an open‐air circulation system. Measurements were performed in four periods (Period I‐IV) covering the body weight range from 25 to 100 kg. In order to achieve maximum protein retention (RP) a daily intake of digestible protein > 12 g/kg0.75 and metabolisable energy > 1100 kJ/kg0.75 was assumed to be necessary. Protein retention of Danish Landrace boars was inferior to that of Hampshire and Duroc boars in Periods III and IV, and therefore, 55 measurements on Hampshire and Duroc boars fulfilling the chosen criteria for digested protein and ME intake were used for calculation of maximum protein retention, giving the following significant quadratic relationship: RP [g/d]= 11.43‐W0.75‐0.144‐W1.50(n = 55, RSD = 15.2, CV = 9.2%, R2 = 0.851) with a summit of 227 g/d at 135 kg BW. In Period I, when BW was below 30 kg, 12 measurements fulfilled the chosen criterion for digested protein but not for ME, and these data were used comparatively. Protein retention of boars with a low ME intake in Period I was significantly below that of boars with a high ME intake (93 g/d vs. 107 g/d; P = 0.02). In summary, the present data have shown that boars of high genetic potential have capacity for maximum protein retention of about 230 g/d, and that there was a significant quadratic relationship between protein retention and metabolic body weight, indicating that maximum protein retention was not reached until 135 kg BW. Differences in capacity for protein retention were recorded between boars of different breeds, with Duroc and Hampshire boars being superior to Danish Landrace boars. Additionally, the crucial importance of a sufficient ME supply early in the growth period was underscored by a lower protein accretion rate of boars given a daily ME supply below 1100 kJ ME/kg0.75 at an approximate BW of 25 kg.

Fattening and slaughter values of pigs in relation to their genotype and to the protein source in their feed rations

The studies were carried out on F1 progeny of multiparous Polish Large White sows and boars of Belgian Landrace, Hampshire x Pietrain hybrid, and Pietrain breed. The control group consisted of purebred Polish Large White pigs. The experimental part of the studies was performed on 120 fatteners divided up to 4 race groups, with 30 heads in each (namely 15 barrows and 15 gilts). Moreover, each group was divided into two following subgroups: the SoS one, which was given feed mixture with extracted soybean meal and the RpS one, which was given feed mixture with extracted rapeseed meal. The fattening started with 23 kg of body weight and was realized up to 100 kg. Twenty fatteners from each group (including 5 barrows and 5 gilts from a subgroup) were subjected to the control slaughter. The fatteners average daily body weight gains, and energy and digestible crude protein conversion per 1 kg of gain were as follows: after Belgain Landrace boars 788 g, 32.3 MJ and 358 g; after Hampshire x Pietrain boars 766 g, 33.6 MJ and 373 g; after Pietrain boars 720 g, 34.4 MJ and 382 g; after control group boars 705 g, 36.3 MJ and 403 g, respectively. It was found that hybrids after boars of evaluated breeds have positively (P < or = 0,01) better carcass meatness, and in a better way use digestible protein and metabolizable energy for production of 1 kg of meat. On that reason the best are hybrids after Belgian Landrace boars, carcasses of which yielded 52.4% of meat and converted 27% less of digestible crude protein and metabolizable energy for 1 kg meat production, than the White Large Polish fatteners. For no examined feature interaction between genotype and protein source in feeding diet was found. The growth rate and utilization of fodder were better for pigs fed on mixture with extracted soybean meal than for the ones fed on mixture with extracted rapeseed meal (P < or = 0.05). The fodders with high protein content did not differentiate meatness traits, whereas digestible crude protein and metabolizable energy conversion for 1 kg meat production in pigs, being given extracted soybean meal in diet, was lower (P < or = 0.05) than in pigs given extracted rapeseed meal.

A major locus (RN) affecting muscle glycogen content is located on pig chromosome 15.

The RN locus in pigs has a major effect on the amount of stored glycogen in white muscle and affects meat quality. The fully dominant RN- allele, associated with high glycogen content, occurs in the Hampshire breed. We have mapped the RN locus using a large half-sib family comprising one heterozygous RN-/rn+ Hampshire boar mated to homozygous rn+/rn+ Swedish Landrace x Swedish Yorkshire sows. The segregation at the RN locus was inferred from data on glycolytic potential and residual glycogen in white muscle which both showed clear bimodal distributions. Highly significant evidence for genetic linkage was obtained against microsatellite markers on Chromosome (Chr) 15. Multipoint analysis revealed the order Sw1111-8.0-S0088-10.6-RN-4.8-Sw936,Sw906 (recombination estimates are given as Kosambi cM). Comparative mapping data imply that the human homolog of RN is located on Chr 2q.

Factors Affecting Performance and Disposition of “Heavy” Purebred Boars

Performance data were collected from 543 purebred boars that were grown to an average body weight of 144kg. Animal weight (WT), daily gain (ADG), and backfat (BF) measures were collected individually, whereas feed conversion (FC) was recorded on a pen basis. Duroc and Yorkshire boars grew at a faster rate (P<.05) than did those of the Hampshire or Landrace breeds. Hampshire boars excelled with reduced BF levels (P<.05) over all other breeds. There were no significant breed differences in FC at these heavy weights.There were significant (P<.05) variations between breeds, within breeds, and within genetic lines in the performance of offspring. The 10 highest performing sirelines (TPI) accounted for 90 (17%) of all boars evaluated. These sirelines included five from the Duroc, four from the Yorkshire, and one from the Hampshire breed. No significant (P<.05) breed differences existed in the auction value of boars. About 16% of the auction sale value was due to price differences among various year, season, and unit combinations. Only 6% could be attributed to changes in current industry prices and 11% explained by the TPI.

Evaluation of the growth performance and carcass characteristics of commercial pigs produced in Quebec

Data for a total of approximately 2900 commercial pigs tested in 12 trials from 1987 to 1990 at the Beaumont test station in Quebec were used to determine the effect of sex, sire breed, cross type and parity number of the dam on growth performance and carcass characteristics. Pigs were housed four to a pen and were fed commercial diets. Feed intake and growth rate were measured during the test, and carcass measurements were taken at slaughter and at 24 or 72 h following slaughter. Castrated males ate more per day, had a better gain and reached slaughter weight (96.4 ± 5.6 kg) at a younger age than gilts. Gilts had a better carcass yield and were leaner than castrated males. Commercial pigs sired from Duroc or Duroc–Hampshire boars had a growth performance superior to that of pigs sired by Landrace, Yorkshire or Hampshire boars. Progeny from Duroc or Duroc–Hampshire boars also produced carcasses with less loin fat, a thicker loin muscle, a higher estimated lean yield and a better classification index. Pigs from three-way crosses had a higher average daily gain and a better feed conversion than pigs from other types of crosses (single, backcross, four-way, synthetic and purebred), and they reached market weight at a younger age. Most carcass characteristics were also affected by the type of cross, but no specific type of cross was clearly superior to the others for the various variables studied. An increase in parity number of the dam caused a gradual decrease in growth performance, except for pigs from parity six, which presented the best results. There was also a linear decrease in loin muscle thickness, estimated lean yield and classification index and a linear increase in loin fat thickness with increase in parity number of the dam. Key words: Pig, growth performance, carcass composition

Vasointestinal polypeptide (VIP)-immunoreactive nerves in the boar penis.

Vasointestinal polypeptide (VIP)-immunoreactivity was localized at LM-level in cryostat sections using a peroxidase-anti-peroxidase technique, and at EM-level in glutaraldehyde-fixed, resin-embedded sections using an immunogold technique, of samples from the penis of 3 Hampshire boars with a history of normal erection and mating behaviour. One boar of the same breed with an impotence diagnosis was also examined. In the normal animals, VIP-immunoreactivity was localized into nerves associated to blood vessels and non-vascular smooth muscle in the capsular lamina propria and the fibromuscular layers, and intermingled under the penis epithelium. At EM level, the immunogold localization confirmed the above mentioned results, VIP being localized in nerve terminals. Nerve terminals without VIP-reactivity had EM appearance of cholinergic or adrenergic nerve terminals. No obvious differences in VIP innervation were noticed among the normal boars. In the impotent animal, a marked depletion of VIP-immunoreactivity was evident, as well as degenerative changes in the adrenergic and cholinergic nerve profiles. It is concluded that the porcine penis is well innervated, along with adrenergic and cholinergic components, by VIP-containing nerves. The depletion of the scattered VIP-containing nerves in the impotent case suggests its involvement in the mechanisms of penile erection in the boar.

Phenotypic Trends Over Time for Performance of Centrally Tested Boars

Performance data of 2769 boars evaluated in a central test station were analyzed to evaluate phenotypic trends from 1971 through 1987 for average daily gain (ADG), pen feed to gain ratio (FG), backfat thickness (BF), and longissimus muscle area (LMA). The study included data from Duroc, Hampshire, Spotted, and Yorkshire boars. Data from several other breed groups were analyzed as a single group (designated Other). All breed groups increased in ADG (linear year eHect, P<.05), averaging 953 gin 1971 vs. 1030 in 1987. Averaged over years, ADG was highest for Duroc and Yorkshire boars and lowest for Other boars. Feed/gain fluctuated over the study period, with a small net improvement (P<.1 0) from 1971 through 1987 for Yorkshire, Hampshire, and Other boars. The change in FG per year among Duroc and Spotted boars was nonsignificant. Averaged over years, FG ranged from 2.45 for Hampshire to 2.60 for Spotted boars. In all breeds, BF decreased from 1978 through 1981, followed by a period of several years with little change and then a slight increase the last 2yr. These trends resulted in little difference between average BF in 1971 vs. 1987. Hampshire boars consistently had less BF than boars of other breed groups. Longissimus muscle area fluctuated with little net change for the entire evaluation period, although there appeared to be a slight upward trend among Hampshire boars from 1982 through 1987. Averaged over years, LMA ranged from 35.0cm2 for Yorkshire to 37.2cm2 for Hampshire boars. Boars tested in recent years in general gained faster, were similar in leanness and LMA, and in some breeds were slightly more efficient compared to boars tested in 1971.

A comparison of the Duroe, Hampshire, Landrace, and Large White as terminal sire breeds of crossbred pigs slaughtered at 85 kg liveweight

Quality assessments were made on samples of M. longissimus tissue from crossbred pigs sired by Duroc, Hampshire, Landrace, and Large White boars slaughtered at 85 kg liveweight. Samples from the Ha...

Association of restriction fragment length polymorphisms of swine leucocyte antigen class I genes with production traits of Duroc and Hampshire boars

Restriction fragment length polymorphism analyses of swine leucocyte antigen (SLA) class I genes were performed on 70 Duroc and 38 Hampshire boars from the 1986-87 national performance tests of each breed in the USA. Few boars were inbred. Southern blotting and hybridization procedures were performed on genomic DNA, isolated from white blood cells, using PvuII endonuclease and a swine major histocompatibility complex (MHC) class I probe. Durocs had an average of 11 restriction fragments, with the most common being in 63% of the boars and the least common appearing in only one boar. Hampshire boars had an average of 12 restriction fragments, with the most common appearing in 73% of the boars and the least common appearing in only one boar. Least squares procedures and stepwise regression methods were used to examine the association between DNA restriction fragments and the selection index (INDEX), average daily gain (ADG), average backfat thickness (BF), loin muscle area (LEA), and age at 104 kg (DAY104). In the Duroc breed one DNA restriction fragment was associated with decreased INDEX (P less than 0.05) and decreased ADG (P less than 0.05) whereas two other fragments were associated with increased BF (P less than 0.05). In the Hampshire breed two restriction fragments were associated with an increase in INDEX (P less than 0.05). Cluster analyses were used to group pigs of each breed on the basis of similar RFLP patterns. One cluster group in the Duroc breed was associated with lower average INDEX values (P less than 0.05), greater average DAY104 (P less than 0.05), and a larger mean LEA (P less than 0.05). In the Hampshire breed one cluster group was associated with lower INDEX (P less than 0.05). These results suggest there may be an association between swine MHC class I genes and performance traits in swine. The use of SLA class I restriction fragments, as genetic markers, may have potential in the future for improving pig performance.

Genetic variability between two breeds based on restriction fragment length polymorphisms (RFLPs) of major histocompatibility complex class I genes in the pig

Restriction fragment length polymorphism analyses of SLA class I genes were performed on 55 Duroc and 24 Hampshire boars from the 1986-87 national performance tests of each breed. Few boars were inbred. Southern blotting and hybridization procedures were performed on genomic DNA isolated from white blood cells by using Pvu II, Bam HI, and Eco RI endonucleases and a swine MHC class I probe. Genetic variability within and between the two breeds was estimated in terms of nucleotide diversity, by using a mathematical analysis based on the different RFLP patterns. The nucleotide diversity calculated within each breed was less than that between the two breeds. The results from the nucleotide diversity analysis suggested that genetic variability was greater in the Duroc breed than in the Hampshire breed. A relatively high level of genetic variability was shown in the class I major histocompatibility complex genes in the pig.

Comparisons of specific crosses from Duroc-Landrace, Yorkshire-Landrace and Hampshire-Landrace sows managed in two types of gestation systems: pig performance.

Ten thousand one hundred sixty-nine pigs were farrowed in 844 litters that were produced by mating Duroc (D), Yorkshire (Y) and Hampshire (H) boars to Duroc-Landrace (DL), Yorkshire-Landrace (YL) and Hampshire-Landrace (HL) sows to study the effect of sire breed, dam breeding and gestation environment (pasture lots vs confinement stalls) on pig weights, survival rates and feed efficiency. Pigs sired by H boars were .05 kg heavier at birth than Y-sired pigs and .2 kg heavier at 21 d than Y- and D-sired pigs, but they were .6 kg smaller at 56 d. D-sired pigs grew .028 kg/d faster from 56 d to 100 kg and reached 100 kg approximately 5 d sooner than the Y- and the H-sired pigs. At birth, pigs out of DL sows were .21 kg heavier than pigs out of YL sows. Pigs out of HL sows grew .025 and .021 kg/d slower from 56 d to 100 kg compared with pigs out of DL and YL sows, respectively. Sows in the pasture gestation system produced pigs that were .05 kg heavier at birth than pigs out of sows in gestation stalls. Three-breed-cross pigs were .9 kg heavier at 56 d, grew .039 kg/d faster and took 7.9 fewer days to reach 100 kg than backcross pigs. The H sire breed had lower survival rates of pigs at 21 d and to 100 kg of those born alive (P less than .10), compared with pigs sired by D and Y boars. Pigs out of HL dams had the highest survival rates, whereas pigs out of YL sows had the lowest survival rates at birth, 21 d and at 100 kg. Three-breed-cross pigs averaged .025, .028 and .035 greater survival rates at birth, 21 d and 56 d than backcross pigs. Feed efficiency was most desirable in pens of pigs sired by H and D boars compared with pens of pigs sired by Y boars. However, pens of pigs with YL dams were more efficient than pens of pigs with HL dams.

Comparative growth performance, carcass characteristics, and meat quality of pigs sired by Hampshire and Landrace boars

Abstract The performance (25 – 85 kg liveweight) of Hampshire x (Landrace x Large WhIte) and Landrace x (Landrace x Large White) progeny was compared under three feeding regimes, namely ad libitum, restricted according to liveweight, and one in which all pigs received the same amount of feed over the same period of time. On each feeding regime, growth performance was similar for the two types of crossbreds, but Hampshire crosses had relatively higher carcass yields, lower backfat measurements, and larger ‘eye muscles’ in cross-section. The eye muscles of Hampshire crosses were paler and had higher drip losses than those of Landrace crosses but only a few carcasses of each breed type had pale, soft, exudative musculature. Breed of sire did not significantly influence the intramuscular fat content of eye muscle tissue.