Deletion variant near ZNF389 is associated with control of ovine lentivirus in multiple sheep flocks.

Ovine lentivirus (OvLV) is a macrophage-tropic lentivirus found in many countries that causes interstitial pneumonia, mastitis, arthritis and cachexia in sheep. There is no preventive vaccine and no cure, but breed differences suggest marker-assisted selective breeding might improve odds of infection and control of OvLV post-infection. Although variants in TMEM154 have consistent association with odds of infection, no variant in any gene has been associated with host control of OvLV post-infection in multiple animal sets. Proviral concentration is a live-animal diagnostic measure of OvLV control post-infection related to severity of OvLV-induced lesions. A recent genome-wide association study identified a region including four zinc finger genes associated with proviral concentration in one Rambouillet flock. To refine this region, we tested additional variants and identified a small insertion/deletion variant near ZNF389 that showed consistent association with proviral concentration in three animal sets (P < 0.05). These animal sets contained Rambouillet, Polypay and crossbred sheep from multiple locations and management conditions. Strikingly, one flock had exceptionally high prevalence (>87%, including yearlings) and mean proviral concentration (>950 copies/µg), possibly due to needle sharing. The best estimate of proviral concentration by genotype, obtained from all 1310 OvLV-positive animals tested, showed insertion homozygotes had less than half the proviral concentration of other genotypes (P < 0.0001). Future work will test additional breeds, management conditions and viral subtypes, and identify functional properties of the haplotype this deletion variant tracks. To our knowledge, this is the first genetic variant consistently associated with host control of OvLV post-infection in multiple sheep flocks.

Mutations in Ovis aries TMEM154 are associated with lower small ruminant lentivirus proviral concentration in one sheep flock.

Small ruminant lentivirus (SRLV), also called ovine progressive pneumonia virus or maedi-visna, is present in 24% of US sheep. Like human immunodeficiency virus, SRLV is a macrophage-tropic lentivirus that causes lifelong infection. The production impacts from SRLV are due to a range of disease symptoms, including pneumonia, arthritis, mastitis, body condition wasting and encephalitis. There is no cure and no effective vaccine for preventing SRLV infection. However, breed differences in prevalence and proviral concentration indicate a genetic basis for susceptibility to SRLV. Animals with high blood proviral concentration show increased tissue lesion severity, so proviral concentration represents a live animal test for control post-infection in terms of proviral replication and disease severity. Recently, it was found that sheep with two copies of TMEM154 haplotype 1 (encoding lysine at position 35) had lower odds of SRLV infection. In this study, we examined the relationship between SRLV control post-infection and variants in two genes, TMEM154 and CCR5, in four flocks containing 1403 SRLV-positive sheep. We found two copies of TMEM154 haplotype 1 were associated with lower SRLV proviral concentration in one flock (P < 0.02). This identified the same favorable diplotype for SRLV control post-infection as for odds of infection. However, frequencies of haplotypes 2 and 3 were too low in the other three flocks to test. The CCR5 promoter deletion did not have consistent association with SRLV proviral concentration. Future work in flocks with more balanced allele frequencies is needed to confirm or refute TMEM154 association with control of SRLV post-infection.

Validation and fine mapping of a QTL for ovulation rate on swine chromosome 3.

Ovulation rate (OR) is an important component of litter size, but mutation(s) in gene(s) underlying OR QTL have yet to be identified in pigs. Markers within an OR QTL on SSC3 were genotyped in three white composite lines selected for ten generations for increased OR or uterine capacity (UC), with one line being an unselected control. Numbers of corpora lutea (CL) and UC (number of fully formed fetuses) were collected at approximately 105 days of gestation, as well as ovary weight (OW), uterine length (UL) and uterine weight (UW) measurements at 160 d of age in generation 12 and 13 females from all three lines. Six microsatellites and ten single nucleotide polymorphisms (SNPs; 0-42 cM) were genotyped in pigs from all lines of generations 11 through 13. The allele frequencies of 24269.1, SW2429, 7907.2 and 7637.2 were different (P < 0.01) in the OR line compared to the control line. A significant (P < 0.05) association of CL with 24269.1 (additive effect 0.65 ± 0.32) was detected, and additive genotypic effects approached significance for markers at 28 through 35 cM (16963.2, 27514.1 and SWR1637). Haplotyping of 7637.2 and 16963.2 (31 through 32 cM) identified a significant additive association of haplotype 1 with CL (-0.62 ± 0.30). These markers were also associated with OW (24296.1 and SWR1637), UL (16963.2, 27514.1 and haplotypes of 7637.2/16963.2) and UW (haplotypes of 7637.2/16963.2). This study verifies an OR QTL on SSC3. However, based on the data, it was concluded that there may be two genes, at 13 through 18 cM and 28 through 35 cM, controlling OR on SSC3p.

Common promoter deletion is associated with 3.9-fold differential transcription of ovine CCR5 and reduced proviral level of ovine progressive pneumonia virus.

Chemokine (C-C motif) Receptor 5 (CCR5) is a chemokine receptor that regulates immune cell recruitment in inflammation and serves as a coreceptor for human immunodeficiency virus (HIV). A human CCR5 coding deletion (termed delta-32) results in strong resistance to HIV infection, and sequence variants in CCR5 regulatory regions have been implicated in delayed progression to acquired immune deficiency syndrome. Both ovine progressive pneumonia virus (OPPV), also known as maedi-visna, and HIV are macrophage-tropic lentiviruses, have similar genomic structures, and cause lifelong persistent host infection, suggesting CCR5 may have a role in regulating OPPV provirus levels. Therefore, the ovine CCR5 genomic sequence was determined, and sequence variants were obtained from the open reading frame and surrounding regulatory sites. One CCR5 variant contained a 4-base deletion within a binding site for octamer transcription factors in the promoter region. A test for differential transcription from each allele in heterozygous animals showed a 3.9-fold transcription difference (P < 0.0001). OPPV proviral levels were also measured in 351 naturally exposed Rambouillet, Polypay and Columbia sheep. Deletion homozygotes showed reduced OPPV proviral levels among these animals (P < 0.01). The association of this CCR5 promoter deletion with OPPV levels will need to be validated in additional populations before the deletion can be recommended for widespread use in marker-assisted selection. However, because of the large impact on transcription and because CCR5 has roles in inflammation, recruitment of effector cells, and cell-mediated immunity, this deletion may play a role in the control of infections of many diverse pathogens of sheep.

Evaluation of Rambouillet, Polypay, and Romanov-White Dorper × Rambouillet ewes mated to terminal sires in an extensive rangeland production system: Lamb production.

Ewe productivity (i.e., total number or weight of lambs weaned per breeding ewe) is a key indicator of lamb production efficiency. This study compared various measures of ewe productivity and ewe and lamb performance among ewes of 3 breed types mated to rams of 4 terminal-sire breed types in an extensive rangeland production system. Purebred Rambouillet ( = 212), purebred Polypay ( = 236), and crossbred Romanov-White Dorper × Rambouillet (RW-RA; = 231) ewes were produced from locally adapted Polypay and Rambouillet ewes and then annually mated to Columbia, Suffolk, Columbia × Suffolk, or Suffolk × Columbia sires for up to 4 yr, beginning at 1 yr of age. The cumulative number and weight of lambs weaned through 4 yr were greater for RW-RA (5.9 lambs and 153 kg, respectively) and Polypay ewes (4.9 lambs and 123 kg, respectively) than for Rambouillet ewes (2.9 lambs and 99 kg, respectively) and also were greater for RW-RA ewes than for Polypay ewes (all < 0.001). Greater productivity of RW-RA and Polypay ewes, compared with Rambouillet ewes, was driven by greater lambing rates (ewes lambing per ewe exposed) as ewe lambs (87 and 77 vs. 31%, respectively; < 0.001) and greater ( < 0.001) litter sizes as ewe lambs (1.3, 1.3, and 1.0, respectively) and adult ewes (2.1, 2.0, and 1.6, respectively). The RW-RA ewes also had greater longevity ( < 0.01) and cumulative lambing rates ( < 0.001) than Polypay and Rambouillet ewes. Lamb BW at birth and weaning in adult ewes favored less-prolific Rambouillet ewes ( < 0.001), but after adjustment for type of birth and rearing and weaning age, differences in weaning BW among ewe breed types were small and not significant ( = 0.08). Effects of sire breed type on measures of cumulative ewe productivity were not significant ( > 0.74), but Suffolk-sired lambs had the heaviest adjusted birth weights ( = 0.01) and Columbia-sired lambs tended to have the lightest adjusted weaning weights ( = 0.12). Combined effects of heterosis and additive breed effects were associated with greater lambing rates in ewe lambs, larger litters at all ages, and substantially greater number and weight of lambs weaned for Polypay and RW-RA ewes than for Rambouillet ewes.

Locomotor activity, core body temperature, and circadian rhythms in mice selected for high or low heat loss.

Daily locomotor activity, core body temperature, and their circadian rhythms were measured in lines of mice selected for high (MH) or low (ML) heat loss and unselected controls (MC). Lines were created by selecting for 16 generations in each of three replicates. Collection of locomotor activity and core temperature data spanned Generations 20 and 21 for a total of 352 mice. Physical activity and core body temperature data were accumulated using implanted transmitters and continuous automated collection. Measurement for each animal was for 3 d. Activity was recorded for each half hour and then averaged for the day; temperature was averaged daily; circadian rhythm was expressed in 12-h (light vs dark) or 6-h periods as well as by fitting cyclic models. Activity means were transformed to log base 2 to lessen heterogeneity of variance within lines. Heat loss for a 15-h period beginning at 1630 and feed intake for 7 d were measured on 74 additional mice in order to estimate the relationship between locomotor activity and heat loss or feed intake. Selection lines were different (P < 0.01) for both locomotor activity and core body temperature. Differences were due to selection (MH-ML, P < 0.01), and there was no evidence of asymmetry of response (P > 0.38). Retransformed from log base 2 to the scale of measurement, mean activity counts were 308, 210, and 150 for MH, MC, and ML, respectively. Mean core temperatures were 37.2, 36.9, and 36.7 degrees C for MH, MC, and ML (P < 0.01), respectively. Females had greater physical activity (P < 0.01) and body temperature (P < 0.01) than males. There was no evidence of a sex x selection criterion interaction for either activity or temperature (P > 0.20). Overall phenotypic correlation between body temperature and log base 2 activity was 0.43 (P < 0.01). Periods during the day were different for both 12- and 6-h analyses (P < 0.01), but there were no period x selection criterion interactions (P > 0.1) for physical activity or body temperature. More sensitive cyclic models revealed significant (P < 0.01) 24-, 12-, 8-, and 6-h cycles that differed (P < 0.01) among lines. Estimated differences between MH and ML mice in feed intake and heat loss due to locomotor activity were 36 and 11.5%, respectively. Variation in activity thus contributed to variation in feed intake.

Evaluation of Columbia, U.S. Meat Animal Research Center Composite, Suffolk, and Texel rams as terminal sires in an extensive rangeland production system: VI. Measurements of live-lamb and carcass shape and their relationship to carcass yield and value.

Linear measurements on live lambs and carcasses can be used to characterize sheep breeds and may have value for prediction of carcass yield and value. This study used 512 crossbred lambs produced over 3 yr by mating Columbia, U.S. Meat Animal Research Center (USMARC) Composite, Suffolk, and Texel rams to adult Rambouillet ewes to assess sire-breed differences in live-animal and carcass shape and to evaluate the value of shape measurements as predictors of chilled carcass weight (CCW), weight of high-value cuts (rack, loin, leg, and sirloin; HVW), weight of trimmed high-value cuts (trimmed rack and loin and trimmed, boneless leg and sirloin; TrHVW), and estimated carcass value before (CVal) and after trimming of high-value cuts (TrCVal). Lambs were produced under extensive rangeland conditions, weaned at an average age of 132 d, fed a concentrate diet in a drylot, and harvested in each year in 3 groups at target mean BW of 54, 61, and 68 kg. Canonical discriminant analysis indicated that over 93% of variation among sire breeds was accounted for by the contrast between tall, long, less-thickly muscled breeds with greater BW and CCW (i.e., the Columbia and Suffolk) compared with shorter, more thickly muscled breeds with smaller BW and CCW. After correcting for effects of year, harvest group, sire breed, and shipping BW, linear measurements on live lambs contributed little to prediction of CCW. Similarly, after accounting for effects of CCW, linear measurements on live animals further reduced residual SD (RSD) of dependent variables by 0.2 to 5.7%, with generally positive effects of increasing live leg width and generally negative effects of increasing heart girth. Carcass measurements were somewhat more valuable as predictors of carcass merit. After fitting effects of CCW, additional consideration of carcass shape reduced RSD by 2.1, 3.6, 9.5, and 2.2% for HVW, TrHVW, CVal, and TrCVal, respectively. Effects of increasing carcass leg width were positive for HVW, TrHVW, and TrCVal. We also observed positive effects of increasing carcass length on TrCVal and negative effects of increasing cannon bone length on HVW and CVal. Increasing shoulder width had positive effects on CVal but negative effects on TrHVW. Differences in lamb and carcass shape were significantly associated with carcass yield and value, but the additional accuracy associated with use of these measurements was modest relative to that achieved from use of only shipping BW or CCW.

Evaluation of Columbia, USMARC Composite, Suffolk, and Texel rams as terminal sires in an extensive rangeland production system: VII. Accuracy of ultrasound predictors and their association with carcass weight, yield, and value.

Use of lamb BW or chilled carcass weights (CCW), live-animal ultrasound or direct carcass measurements of backfat thickness (BF; mm) and LM area (LMA; cm(2)), and carcass body wall thickness (BWall; mm) to predict carcass yield and value was evaluated using 512 crossbred lambs produced over 3 yr by mating Columbia, U.S. Meat Animal Research Center Composite, Suffolk, and Texel rams to adult Rambouillet ewes. Lambs were harvested at 3 BW endpoints within each year. The predictive value of 3 to 5 additional linear measurements of live-animal or carcass size and shape was also evaluated. Residual correlations (adjusted for effects of year, breed, and harvest group) between ultrasound and direct measurements were 0.69 for BF and 0.65 for LMA. Increasing ultrasound or carcass LMA had positive effects (P < 0.001) on yield of chilled carcass (i.e., on dressing percentage) and, at comparable CCW, on weight of high-value cuts (rack, loin, leg, and sirloin) before trimming (HVW), weight of trimmed high-value cuts (trimmed rack and loin and trimmed boneless leg and sirloin; TrHVW), and carcass value before (CVal) and after (TrCVal) trimming of high-value cuts. By contrast, ultrasound and direct measures of BF had positive effects on yields of CCW and on HVW and CVal but large negative effects on TrHVW and TrCVal. After adjusting for BW at scanning, increases of 1 mm in ultrasound BF or 1 cm(2) in ultrasound LMA were associated with changes of US$-0.32 (P < 0.10) and $1.62 (P < 0.001), respectively, in TrCVal. Carcass BWall was generally superior to carcass BF as a predictor of TrHVW and TrCVal. Carcass LMA was superior to ultrasound LMA but carcass BF was inferior to ultrasound BF for prediction of carcass yield and value. Increasing LMA thus would be expected to improve carcass yield and value. Addition of linear measurements of live-animal or carcass size and shape to the prediction model reduced residual SD (RSD) for TrHVW and TrCVal by 0.4 to 2.2%, but subsequent removal of ultrasound or direct measures of BF and LMA from the prediction model increased RSD by 7.4 to 12.2%. Measurements of CCW, LMA, BF, and BWall would thus be appropriate to support programs for value-based marketing of lamb carcasses and are superior to systems based only on measurements of size and shape in unribbed carcasses.

Evaluation of Columbia, USMARC-Composite, Suffolk, and Texel rams as terminal sires in an extensive rangeland production system: VIII. Quality measures of lamb longissimus dorsi.

Quality measures of lamb longissimus dorsi were evaluated in 514 crossbred wether lambs to assess sire breed differences. Wethers were produced over 3 yr from single-sire matings of 22 Columbia, 22 U.S. Meat Animal Research Center (USMARC)-Composite (Composite), 21 Suffolk, and 17 Texel rams to adult Rambouillet ewes. Lambs were reared to weaning in an extensive western rangeland production system and finished in a feedlot on a high-energy finishing diet. One of three harvest groups were randomly assigned to each lamb, and lambs were transported to The Ohio State University abattoir when the mean BW of wethers remaining in the feedlot reached 54.4, 61.2, or 68.0 kg. After harvest, subjective lean quality scores were assigned and LM pH (immediately after and 24 h after harvest), color (quantified as Minolta L*, a*, and b*), intramuscular fat (IMF), cooking loss percentage, and Warner-Bratzler shear force (WBSF) were determined. Statistical models included fixed effects of sire breed, year of birth, and harvest group and random effects of sire (nested within sire breed and year) and maternal grandsire. Year and harvest group were significant (P < 0.04) for all traits, except harvest group was not for WBSF and lean quality (P > 0.28). At comparable numbers of days on feed, Texel-sired wethers had the greatest (more desirable; P < 0.01) subjective lean quality scores while Composite- and Suffolk-sired lambs were intermediate and Columbia-sired lambs had the lowest (less desirable). Minolta L* values were greater (P < 0.02) for Texel- than Columbia-sired lambs, although this difference is not visually discernible by humans. No significant (P > 0.05) sire breed effects were detected for LM pH at or 24 h after harvest, Minolta a* and b*, IMF, percentage of cooking loss, and WBSF at comparable numbers of days on feed. At comparable chilled carcass weight, significant (P < 0.01) sire breed effects were detected for subjective lean quality score. Texel-sired lambs had greater scores than Columbia- and Suffolk-sired lambs, but Composite-sired lambs did not differ from lambs sired by the other sire breeds. Sire breed effects were not detected (P > 0.15) for LM pH at or 24 h after harvest, Minolta L*, a*, and b*, cooking loss percentage, IMF, and WBSF at comparable chilled carcass weight. Therefore, results of the present study indicated that the 4 sire breeds produced crossbred lamb carcasses that had similar and desirable LM quality measurements, meeting consumer expectations.

Evaluation of Columbia, USMARC-Composite, Suffolk, and Texel rams as terminal sires in an extensive rangeland production system: IV. Postfabrication carcass component weights.

Postfabrication carcass component weights of 517 crossbred wether lambs were analyzed to evaluate 4 terminal-sire breeds. Wethers were produced over 3 yr from single-sire matings of 22 Columbia, 22 USMARC-Composite (Composite), 21 Suffolk, and 17 Texel rams to adult Rambouillet ewes. Lambs were reared to weaning in an extensive western rangeland production system and finished in a feedlot on a high-energy finishing diet. When wethers reached a mean BW of 54.4, 61.2, or 68.0 kg, they were transported to The Ohio State University abattoir for harvest. After refrigeration for approximately 24 h, chilled carcass weight (CCW) was measured, carcasses were fabricated according to Style A of Institutional Meat Purchase Specifications, and postfabrication weights were recorded. At comparable numbers of days on feed, Suffolk-sired lambs had heavier (P < 0.04) neck, breast, shoulder, foreshank, rack, loin, leg, sirloin, roast-ready rack, trimmed loin, and boneless leg cuts than progeny of the other sire breeds. Boneless sirloins were heavier (P < 0.01) for Suffolk-sired than Composite-sired lambs but did not differ from those for Columbia- or Texel-sired lambs. Columbia- and Suffolk-sired lambs had heavier (P < 0.01) hindshanks than Texel-sired lambs. Suffolk-sired lambs had heavier (P < 0.01) high-value cuts (rack, loin, leg, and sirloin) and trimmed high-value cuts than progeny of the other sire breeds. Cutting loss (CCW - wholesale cut weights) and high-value trimming loss were greatest (P < 0.02) for Suffolk-sired lambs and least for Texel- and Composite-sired lambs. Sire breed did not affect (P > 0.06) flank weight. Data adjusted to comparable CCW reduced the number of significant sire-breed effects and changed sire-breed rankings of carcass component weights, for which sire breeds differed. After adjusting, Suffolk-sired lambs had lighter (P < 0.05) loins than Columbia- and Composite-sired lambs, Composite-sired lambs had heavier (P < 0.05) high-value cuts than Suffolk-sired lambs, and Suffolk- and Columbia-sired lambs had heavier (P < 0.05) necks than Texel-sired lambs. At predicted backfat thickness of 6.6 mm, Composite-sired lambs had a greater (P < 0.05) percentage of high-value cuts than Suffolk-sired lambs before but not after trimming. Producers can use these results to select terminal-sire breeds that will complement their production system and improve lamb value.

Evaluation of Columbia, USMARC-Composite, Suffolk, and Texel rams as terminal sires in an extensive rangeland production system: V. Postweaning growth, feed intake, and feed efficiency.

This study was conducted to quantify differences in feed efficiency among 4 sire breeds using records from 1,109 crossbred lambs over 3 yr. Lambs were produced from mating Columbia, USMARC-Composite (Composite), Suffolk, and Texel rams to adult Rambouillet ewes. After weaning, lambs were finished on a high-energy diet in group-fed pens. Efficiency was assessed at 45 and 90 d on study, 50 and 60 kg of BW, and 6.6 and 9.1 mm of fat depth between the 12th and 13th ribs. Sire breed affected most of the traits that were measured. At 90 d, Suffolk-sired lambs had gained 13 to 19% more BW (P < 0.001), were 7 to 13% heavier (P < 0.001), and had consumed 4 to 11% more (P < 0.001) ME than the other breed crosses. However, at 90 d, G:F (59.9 vs. mean of 56.2 g BW gain/Mcal of ME; P < 0.01) and residual BW gain (RG; 0.94 vs. -0.33 kg BW; P < 0.05) were greater for Suffolk-sired lambs than for the other 3 sire breeds. Also, RG for Suffolk-sired lambs was greater (P < 0.01) at 6.6 and 9.1 mm of fat depth (0.62 vs. -0.24 kg and 0.87 vs. -0.33 kg of BW, respectively) and at 60 kg of BW (0.73 vs. 0.31 kg of BW) than for the other sire breeds. At 90 d, Columbia-sired lambs had the greatest (P < 0.01) residual feed intake (RFI; 7.01 vs. mean of -2.33 Mcal ME for the 3 other sire breeds). At 60 kg of BW, Texel- and Composite- (-2.34 Mcal ME, combined) had more favorable (P < 0.01) RFI than Columbia-sired lambs (6.42 Mcal ME), and Suffolk-sired lambs (0.49 Mcal ME) were intermediate and not different from the other 3 sire breeds. At 6.6 mm of fat depth, Columbia- and Suffolk- (3.30 Mcal ME, combined) had greater (P < 0.001) RFI than Texel-sired lambs (-4.23 Mcal ME); at 9.1 mm of fat depth, Columbia-sired lambs had the greatest (P < 0.05) RFI (7.35 vs. -2.11 Mcal ME for the other breeds combined). In summary, except for ME intake at 90 d, Suffolk-sired lambs were equal or superior to Columbia-, Composite-, and Texel-sired lambs for BW, BW gain, ME intake, G:F, RFI, and RG to 90 d, 60 kg of BW, and 9.1 mm of fat depth. Breed rankings were consistent across the study period for G:F and RG, but rankings changed over time for RFI.

Evaluation of Columbia, USMARC-Composite, Suffolk, and Texel rams as terminal sires in an extensive rangeland production system: III. Prefabrication carcass traits and organ weights.

To evaluate terminal-sire breeds, harvest BW, prefabrication carcass measurements, and organ weights were evaluated over 3 yr for 518 crossbred wether lambs (ovis aries). Lambs were produced by single-sire matings of 22 Columbia, 22 USMARC-Composite (Composite), 21 Suffolk, and 17 Texel rams to adult Rambouillet ewes. Lambs were raised to weaning under an extensive western rangeland production system and finished in a feedlot on a high-energy finishing diet. Wethers were randomly assigned to be harvested at an average BW of 54.4, 61.2, or 68.0 kg and then transported to The Ohio State University abattoir for harvest. Wether BW was recorded before transport (off-test BW) and before harvest. Prefabrication carcass measurements and organ weights were recorded either after harvest or after an approximate 24-h chill. At comparable numbers of days on feed, Suffolk-sired lambs had heavier (P < 0.01) off-test BW, harvest BW, HCW, chilled carcass weight (CCW), and kidney weights than lambs sired by the other breeds. Suffolk-sired lambs had more (P < 0.01) kidney-pelvic fat than did Columbia-sired lambs; Composite- and Texel-sired lambs were intermediate and did not differ (P > 0.06) from the other crossbred lambs. Texel- and suffolk-sired lambs had larger lm area and greater conformation scores than Columbia-sired lambs (P < 0.03). Texel-sired lambs had greater (P < 0.01) body wall thickness, quality grades, and leg scores than Columbia-sired lambs. Composite- and Suffolk-sired lambs did not differ from each other or from lambs sired by any other breed for body wall thickness (P > 0.18) and were intermediate for quality grades and leg scores. Sire breed did not affect (P > 0.05) shipping shrink, dressing percentage, pelt weight, liver weight, and fat depth. Adjusting data to a comparable off-test BW or CCW modified sire breed rankings for some measurements. Texel-sired lambs were equal or superior to lambs sired by other breeds for HCW, CCW, dressing percentage, pelt weight, LM area, quality grade, and leg and conformation scores. However, Texel-sired lambs also had values for kidney-pelvic fat weight, fat depth, and body wall thickness that were equal to or greater than those of lambs sired by the other breeds, indicating increased fatness at comparable BW. Producers can use these results to select terminal-sire sheep breeds that will complement their production system and improve market lamb value.

Evaluation of Columbia, USMARC-Composite, Suffolk, and Texel rams as terminal sires in an extensive rangeland production system: II. Postweaning growth and ultrasonic measures of composition for lambs fed a high-energy feedlot diet.

Over 3 yr, postweaning growth patterns and changes in ultrasonic measurements of fat depth (FD) and LM area were assessed for 1,049 crossbred ewe and wether lambs (Ovis aries) produced by mating adult Rambouillet ewes to 1 of 22 Columbia, 22 USMARC-Composite (Composite), 21 Suffolk, or 17 Texel rams and raised to weaning under extensive Western rangeland conditions. After weaning, lambs were transitioned to a high-energy finishing diet in a feedlot, weighed weekly for 13 to 16 wk, and scanned using ultrasound at 2-wk intervals to estimate FD and LM area between the 12th and 13th ribs. Lambs sired by Suffolk rams were 5 to 12% heavier (P < 0.05) at start of test, grew 14 to 22% faster (P < 0.001), and were correspondingly 7 to 14% heavier (P < 0.001) after 90 d on test than lambs sired by rams of the other 3 breeds. At this time, lambs sired by Texel rams were 5% lighter (P < 0.01) than Columbia- or Composite-sired lambs, which did not differ (P > 0.20). Columbia-sired lambs had less FD (8.9 mm) but smaller LM areas (15.6 cm(2)) at 90 d on test (both P < 0.01) than lambs sired by rams of the other breeds (average of 9.8 mm for FD and 16.6 cm(2) for LM area), which did not differ for either measurement at this time. At 60 kg, predicted FD differed among sire breeds (P < 0.001) and were similar for Suffolk- (7.6 mm) and Columbia-sired (7.9 mm) lambs, intermediate for Composite-sired lambs (9.1 mm), and largest for Texel-sired (10.1 mm) lambs. At a BW of 60 kg, LM area differed between all pairs of sire breeds (P < 0.05), and was largest for Texel-sired lambs (16.7 cm(2)), followed by Composite-, Suffolk-, and Columbia-sired lambs (15.7, 14.8, and 14.5 cm(2), respectively). At a predicted FD of 9.1 mm (the boundary between U.S. Yield Grades 3 and 4), the predicted LM area for Suffolk-sired lambs (16.2 cm(2)) was similar (P > 0.10) to that of Texel-sired lambs (16.0 cm(2)) and superior (P < 0.01) to that of Composite- (15.7 cm(2)) and Columbia-sired lambs (15.4 cm(2)). Lambs sired by Suffolk rams were thus equal or superior to lambs sired by the other 3 breeds in growth, FD, and LM area at comparable ages, fatness at 60 kg, and LM area at a FD of 9.1 mm, but inferior in LM area to Texel- and Composite-sired lambs at comparable BW.

Evaluation of Columbia, USMARC-Composite, Suffolk, and Texel rams as terminal sires in an extensive rangeland production system: I. Ewe productivity and crossbred lamb survival and preweaning growth.

A 3-yr study was conducted to comprehensively evaluate Columbia, Suffolk, USMARC-Composite (Composite), and Texel breeds as terminal sires in an extensive rangeland production system. The objective was to estimate breed-of-ram effects on ewe fertility, prolificacy, and dystocia, and sire breed effects on lamb survival and growth until weaning at approximately 132 d of age. Data were from 22 Columbia, 22 Composite, 21 Suffolk, and 17 Texel rams with 957 exposures to 574 adult Rambouillet ewes (3- to 7-yr-old at lambing), 908 lambings, and 1,834 lambs. Ram breed did not affect ewe fertility (mean = 94.9%; p = 0.73), total number born per ewe lambing (mean = 2.02 lambs; p = 0.20), number born alive per ewe lambing (mean = 1.90 lambs; p = 0.24), or number weaned per ewe lambing (mean = 1.45 lambs, p = 0.94). Dystocia rates were different (p = 0.01) for ewes mated to Columbia (12.2%), Composite (13.5%), Suffolk (25.7%), and Texel rams (31.9%) during 1 yr of the study, but differences among ram breeds were not repeatable (p ≥ 0.38) during the other 2 yr. Suffolk-sired lambs were heavier (p ≥ 0.02) at birth (5.5 kg) and weaning (40.3 kg) than lambs sired by the other breeds, which did not differ (p ≥ 0.34) for birth weight (mean = 5.3 kg). Texel-sired lambs (37.4 kg) were lighter (p ≥ 0.02) at weaning than Columbia- (38.8 kg) and Composite-sired (38.4 kg) lambs, which did not differ (p = 0.40) for weaning weight. Sire breed effect approached significance (p = 0.06) for lamb survival to weaning; estimated survival probabilities were 0.87 (Columbia), 0.89 (Composite), 0.93 (Suffolk), and 0.86 (Texel) for lambs reared by their birth dam. Interaction between sire breeds and birth weight affected (p < 0.001) lamb survival and revealed that lightweight Columbia- and Suffolk-sired lambs had a greater risk of death than lightweight lambs sired by Composite and Texel rams, but risk of death did not increase substantially for heavyweight lambs from any of the breeds. When mated to adult Rambouillet ewes in an extensive rangeland production system, the use of Suffolk rams is warranted to improve preweaning growth of market lambs and is not predicted to affect ewe fertility, ewe prolificacy, dystocia, or lamb survival compared with the other sire breeds we tested.

Technical Note: Comparison of traditional needle vaccination with pneumatic, needle-free vaccination for sheep.

Lateral transmission of blood-borne diseases can occur when a single needle is used repeatedly to vaccinate livestock. Needle-free technology to vaccinate sheep without damaging the carcass, causing lesions, or leaving needle fragments, and eliciting a similar antibody response as traditional needle vaccinations, has been hampered due to variable wool length. Vaccine delivery, injection time, and antibody response were evaluated for a prototype pneumatically powered, needle-free injector and for traditional needle injections. To determine optimal pressure for vaccine delivery with the pneumatic, needle-free injector, two 8-mo-old wethers were injected at pressures from 207 to 414 kPa in increments of 69 kPa. Injection time and antibody responses were evaluated using one hundred 8-mo-old wethers given primary and secondary inoculations of ovalbumin. Serum samples were collected before and after the inoculations on d 0, 14, 28, and 42. Optimal pressure to deliver a s.c. inoculation with the pneumatic, needle-free injector was 207 to 276 pKa. Inoculation of 100 wethers required 60% less time with the pneumatic, needle-free injector than with needle injections when a new needle was used on every animal. Antibody titers were the same (P > 0.12) for the pneumatic, needle-free and the needle injections on d 14, 28, and 42. In addition, antibody titers increased after primary and secondary inoculations, as expected. This study indicated that a pneumatic, needle-free injector can be used to elicit the same antibody response in sheep as a needle injection, and the pneumatic, needle-free injector was faster. The pneumatic, needle-free injector also would be expected to reduce lateral transmission of blood-borne diseases, and will save time, eliminate biohazard waste (e.g., used needles), and eliminate accidental needle sticks for livestock handlers when vaccinating sheep.

B-mode, real-time ultrasound for estimating carcass measures in live sheep: accuracy of ultrasound measures and their relationships with carcass yield and value.

Accuracy and repeatability of live-animal ultrasound measures, and the relationships of these measures with subprimal yields and carcass value, were investigated using data from 172 wethers. Wethers were F(1) progeny from the mating of 4 terminal sire breeds to Rambouillet ewes and were finished in a feedlot to a mean BW of 62.9 kg (SD = 9.5 kg). Before transport to slaughter, LM area, LM depth, and backfat thickness were measured from transverse ultrasound images taken between the 12th and 13th ribs. After slaughter, these measures were taken on each carcass. Carcasses were fabricated into subprimal cuts, and weights were recorded. Ultrasound accuracy and repeatability were assessed using bias, SE of prediction, SE of repeatability, and simple correlations. Relationships among ultrasound and carcass measures, and between these measures and carcass yield and value, were evaluated using residual correlations and linear prediction models. Ultrasound bias approached 0 for LM area, and backfat thickness was overestimated by only 0.69 mm. The SE of prediction and r were 1.55 cm(2) and 0.75 for LM area, and 1.4 mm and 0.81 for backfat thickness, respectively. The SE of repeatability was 1.31 cm(2) and 0.75 mm for LM area and backfat thickness, respectively. At a standardized BW and backfat thickness, wethers with larger LM area and LM depth yielded larger and more valuable carcasses, and these relationships were detectable with ultrasound. For each SD increase in carcass LM area, dressing percentage increased 1.57 percentage points, gross carcass value increased US$5.12, and boxed carcass value increased US$6.84 (P < 0.001). For each SD increase in ultrasound LM area, dressing percentage increased 0.95 percentage points, gross carcass value increased US$3.15, and boxed carcass value increased US$3.86 (P < 0.001). When LM area effects were adjusted for carcass weight, the response in boxed carcass value attributed to disproportionate increases in high-value subprimal cut weights was small. Associations of dressing percentage and carcass value with ultrasound and carcass LM depth were significant (P < 0.01) but smaller than corresponding associations with LM area. These data indicate biological and economical incentives for increasing LM area in wethers, and live-animal ultrasound can provide reliable estimates of carcass measures. These results are applicable to terminal sire breeders and producers who market sheep using carcass-merit pricing systems.

Rearranged gene order between pig and human in a quantitative trait loci region on SSC3.

A quantitative trait locus (QTL) for ovulation rate on chromosome 3 that peaks at 36 cM has been identified in a Meishan-White composite resource population with an additive effect of 2.2 corpora lutea. As part of an effort to identify the responsible gene(s), typing of additional genes on the INRA-University of Minnesota porcine radiation hybrid (IMpRH) map of SSC3 and comparative analysis of gene order was conducted. We placed 52 known genes and expressed sequence tags, two BAC-end sequences and one microsatellite (SB42) on a framework map that fills gaps on previous RH maps. Data were analysed for two-point and multipoint linkage with the IMpRH mapping tool and were submitted to the IMpRH database (http://imprh.toulouse.inra.fr/). Gene order was confirmed for 42 loci residing in the QTL region (spanning c. 17 Mb of human sequence) by using the high-resolution IMpRH2 panel. Carthagène (http://www.inra.fr/internet/departments/MIA/T/CarthaGene) was used to estimate multipoint marker distance and order using all public markers on SSC3 in the IMpRH database and those typed in this study. For the high-resolution map, only data for markers typed in both panels were used. Comparative analysis of human and porcine maps identified conservation of gene order for SSC3q and multiple blocks of conserved segments for SSC3p, which included six distinct segments of HSA7 and two segments of HSA16. The results of this study allow significant refinement of the SSC3p region that contains an ovulation rate QTL.