Effects of narasin or virginiamycin on growth performance and carcass characteristics of growing and finishing pigs.

The objective of this experiment was to determine the effects of narasin (NAR; Skycis®; Elanco Animal Health, Greenfield, IN) or virginiamycin (VIR; Stafac®; Phibro Animal Health Corporation, Teaneck, NJ) on finishing pig growth performance and carcass characteristics. Two separate experiments were conducted at the same site in 2013 and 2014. A total of 576 pigs (initial BW = 23.2 ± 0.19 kg) were housed in 24 pens with 8 pigs per pen in Exp. 1. In Exp. 2, a total of 888 pigs (initial BW = 26.2 ± 0.12 kg) were housed in 39 pens with 8 pigs per pen. Treatments consisted of a series of unmedicated corn-soybean meal diets (CON), CON + NAR (15 mg/kg), or CON + VIR (11 mg/kg) fed for 108 d (Exp. 1) or 109 d (Exp. 2). Pen was the experimental unit in both studies. Data were analyzed as a randomized complete block design with the main effects of block and treatment (Exp. 1) and as an incomplete block design with the fixed effect of treatment and the random effects of barn and barn within block (Exp. 2). In Exp.1, NAR and VIR increased (P < 0.05) ADG and ADFI from days 0 to 28, and BW on days 28, 56, 76, and 97 as compared to pigs fed CON. During days 0-28, pigs fed NAR had a greater (P < 0.05) G:F than those fed CON or VIR. Also, during days 28-56 pigs fed VIR had a greater (P < 0.05) ADFI than pigs fed CON. Pigs fed NAR or VIR had greater (P < 0.05) carcass yield than those fed CON. In Exp.2, feeding NAR increased (P < 0.05) pig BW from days 54 through 96 compared to pigs fed CON or VIR. No differences (P > 0.05) in ADG were detected between pigs fed VIR and CON through the first 74 day, but ADG of pigs fed VIR was similar to (P > 0.05) those fed NAR from days 26 to 54. From day 0 to 109, NAR improved ADG compared to pigs fed VIR, which also had similar gain to those consuming CON (P = 0.04). Feed efficiency was similar between pigs fed NAR and VIR with pigs fed CON intermediate (P = 0.05). Pigs fed NAR had a greater (P < 0.05) HCW and loin depth than those fed CON or VIR. A subtherapeutic dose of VIR showed improvements in growth performance that were similar to NAR in one experiment. Although there were differences in the magnitude of growth and carcass effects of NAR between the two studies, pigs fed NAR showed at least a tendency to have greater G:F and in some cases increased carcass weight and yield compared to pigs consuming nonmedicated feed.

Impact of Pichia guilliermondii on sow, litter, and weaned pig immune performance.

Three groups of gestating gilts and sows (Exp. 1; n = 98) were used to determine the effects of Pichia guilliermondii (Pg), a whole yeast product (CitriStim, ADM Alliance Nutrition), on dam and litter immune parameters. At breeding, gilts and sows were allotted to 1 of 3 treatments maintained through lactation: sow control (SC) diet or SC supplemented with 0.1 (S1) or 0.2% (S2) Pg. Pigs from groups 1 (Exp. 2) and 2 (Exp. 3) were weaned (21 d) and allotted in a 3 (SC, S1, or S2) × 2 [nursery with Pg (NPg) or without Pg (NC)] factorial arrangement in a randomized complete block design. In Exp. 2 blood samples were collected on days 5 and 28 postweaning for analysis. In Exp. 3, 36 pigs were individually penned and challenged with lipopolysaccharide (25 µg/kg BW intramuscular; 0 h). Individual BW, ADFI, and rectal temperature (RT) were collected at -48, -24, 0, 24, and 48 h and blood samples were collected at 0, 5, and 24 h for analysis. In Exp. 1, total neutrophil count (NEU) and neutrophil:lymphocyte ratio (NLR) were greater on day 110 of gestation (P < 0.05) in S1 than SC. At weaning there was a liner increase (P < 0.05) in NEU, NLR, and percentage of total leukocytes (PTL) that were NEU as level of Pg increased in sow diets. In Exp. 2, pigs from S1 had increased (P < 0.05) overall IgG than SC. The PTL that were eosinophils was greater in pigs from S2 fed NPg on day 5 than NC (P < 0.05) and increased in all pigs from S2 on day 28 (sow linear, P < 0.1). On day 28, total leukocytes and eosinophils were increased in pigs from SC [quadratic response (Q), P < 0.05]. In Exp. 3, a linear increase (P < 0.05) in ADFI was observed at -24 to 0 h, -48 to 0 h, and 24 to 48 h as the level of Pg increased in sow diets. There was a linear increase in RT at -48, -24, 0, and 5 h with increasing Pg inclusion in sow diets (P < 0.05). However, RT decreased more from 5 to 24 h in pigs from sows receiving Pg. The number of monocytes and PTL that were monocytes were higher in S2 compared to SC and S1 (P < 0.05). Also, NEU were reduced at 5 h in S1 (P < 0.05), NLR was lower in S2 at 0 h and S1 at 5 h, IL-1ß concentration was greater in SC at 0 h and S1 at 5 h, and IL-6 concentration was greater in S2 at 0 h and S1 at 5 h (P < 0.05). Furthermore, blood urea N (BUN) was higher in NC at 0 and 5 h than NPg (P < 0.05). In conclusion, Pg appears to impact immune response criteria of sows and weaned pigs.

Maternal effects on traits measured during postweaning performance test of swine from four breeds.

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.

Genetic parameters for production traits and measures of residual feed intake in large white swine.

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

Attentional bias in normal subjects performing visual and tactile radial line bisections.

Misbisection of lines is thought to represent an attentional bias. When radial lines (intersection of the midsagittal and transverse planes) are presented below eye level, normal subjects are biased toward far peripersonal space in the visual modality and to near peripersonal space in the tactile modality. These errors may be related to a body centered, a retinotopic, or an object centered attentional bias. The purpose of this study was to contrast the body centered and retinotopic-objective centered hypotheses by having 12 normal subjects perform visual and tactile bisections of radial lines that are above and below eye level. The top of the page, which may be defined by retinotopic or object centered coordinates, contains the portion of the line that is most distant from our bodies when the page is below eye level. However, above eye level, the top of a radial line would be the portion of the page that is most proximal to our bodies. We observed that when stimuli are presented below eye level, normal subjects have a visual bias toward far peripersonal space or the top of the page or both, and have a tactile bias in the opposite direction. In the above eye position we found no overall bias in either modality. Because above eye level the body centered bias should have remained the same but the retinotopic or object centered bias should have reversed, our results suggest that the body and object centered or retinotopic biases, which are oriented in opposite directions, nullified each other.

Effects of 84-, 112- and 140-day postweaning feedlot performance tests for beef bulls.

Changes in performance traits in beef cattle over the last 30 yr necessitate the re-evaluation of central testing procedures to ensure that they are cost effective and appropriate for current test objectives. The objective of this study was to evaluate the potential for reducing the length of evaluation from 140 d to either 112 or 84 d. Data evaluated were postweaning feedlot performance test records (collected from 1977 to 1986) on 1,830 individually fed bulls. Bulls representing 13 breeds (n greater than 25 per breed) were evaluated in the University of Arkansas Cooperative Bull Tests at Fayetteville, Hope, and Monticello, Arkansas. Models were fit for ADG, daily feed intake (FI) and feed conversion (FCONV) from d 1 to d 140 (ADG1-140, FI1-140 and FCONV1-140, respectively) and from d 1 to d 112 (ADG1-112, F11-112 and FCONV1-112, respectively). Models fit for ADG1-140, FI1-140, and FCONV1-140 using information up to d 112 had R2 of .90, .99, .88, and .94, respectively, and using information up to d 84 had R2 of .82, .94, and .80, respectively. Spearman rank correlation coefficients (all P less than .0001) were .93 for ADG1-140 and ADG1-112, .93 for ADG1-112 and ADG1-84, .99 for FI1-140 and FI1-112, .91 for FCONV1-140 and FCONV1-112, and .90 for FCONV1-112 and FCONV1-84. These coefficients indicate that bulls ranked similarly for performance traits at 84, 112, and 140 d. If the primary objective of central station testing is to evaluate ADG during the linear phase of growth, and if testing procedures are those currently recommended by the Beef Improvement Federation, then feeding bulls beyond 112 d has no advantage because the information upon which selection decisions are made is similar at both 112 and 140 d.

Breed means for average daily gain, feed conversion and intake of beef bulls during postweaning feedlot performance tests.

Comparisons of ADG, feed/gain, daily feed intake and daily feed intake as percentage of body weight may be important to beef cattle producers and researchers in breed selection and computer modeling. Data evaluated were postweaning feedlot performance test records collected from 1967 to 1986 of 3,661 individually fed bulls. Bulls originated from University of Arkansas purebred herds, Fayetteville, and the University of Arkansas Cooperative Bull Tests at Fayetteville, Hope and Monticello. Data were analyzed separately for years 1967 to 1976 (P1) (n = 1,654) and 1977 to 1986 (P2) (n = 2,007). Breeds in P1 were Hereford (HH), Angus (AN), Charolais (CH), Polled Hereford (HP) and Santa Gertrudis (SG). Breeds in P2 were HH, AN, CH, HP, SG, Simmental (SM), Maine-Anjou (MA), Brangus (BN) and Beefmaster (BM). The model fitted included initial age, breed and test number (all P less than .01 except for initial age on ADG in P1). Test number included variation of year, location and season. Breed rankings from highest to lowest for ADG in P1 were CH, SG, HH, HP and AN and in P2 were MA, CH, SM, AN, HP, SG, HH, BN and BM. Breed rankings from highest to lowest for feed/gain in P1 were AN, SG, CH, HP and HH and in P2 were BM, BN, AN, SG, HP, SM, HH, MA and CH. Breeds highest to lowest for daily feed intake (as-fed basis) in P1 were CH, SG, AN, HP and HH and in P2 were SM, MA, CH, AN, BN, HP, SG, HH and BM.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationships among absolute growth rate, relative growth rate and feed conversion during postweaning feedlot performance tests.

Knowledge of the relationships between absolute growth rate (AGR), relative growth rate (RGR) and feed conversion (FCONV) of bulls in postweaning feedlot performance tests can give cattle producers important information for selecting superior sires. Weight gain and FCONV data that were collected during 16 yr were analyzed from 393 Angus and 340 Hereford bulls by 26 and 27 sires, respectively, that were individually fed in 140-d tests. Sire variance and covariance components were used to obtain heritability (h2) estimates for AGR, RGR and FCONV and the genetic correlations (rg) and phenotypic correlations (rp) among these traits. Respective mean AGR, RGR and FCONV were 1.27 +/- .14 kg/d, .4378 +/- .0395%/d and 7.32 +/- .58 kg/kg for the Angus and 1.28 +/- .12 kg/d, .4552 +/- .0388%/d and 6.56 +/- .46 kg/kg for the Hereford bulls. Estimates of h2 were similar for AGR and RGR in both Angus (.36 +/- .11 and .22 +/- .09) and Hereford (.33 +/- .11 and .20 +/- .09) bulls. The h2 estimates for FCONV were .14 +/- .07 for Angus and .13 +/- .08 for Herefords. For the Angus and Hereford bulls, respectively, rg were .86 +/- .09 and .86 +/- .13 between AGR and RGR, -.84 +/- .38 and -.74 +/- .49 between AGR and FCONV and -.84 +/- .49 and -.61 +/- .64 between RGR and FCONV. The rp were .80 +/- .03 and .68 +/- .04 between AGR and RGR, -.58 +/- .05 and -.51 +/- .05 between AGR and FCONV and -.71 +/- .04 and -.73 +/- .04 between RGR and FCONV for the Angus and Hereford bulls, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)