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This experiment was conducted to determine the impact of a fish-porcine-microbial peptide cocktail (FPM) with/o ZnO supplementation on growth performance in nursery pigs fed diets containing low or adequate crude protein. A total of 288 weaned pigs (21 d) were blocked by initial BW and allotted to pens. (6 replicates per treatment). Pens were randomly assigned to 1 of 8 dietary treatments: 1) Adequate protein (AP) with ZnO and Fishmeal (phase 2, FM) or soybean meal (phase 3, SBM). 2) low protein (LP) diet devoid FM in phase 2 and reduced SBM in phase 3. 3–8) LP ZnO free diet in nursery phase 2/3 with increasing FPM (0.05, 0.25, 0.5%) with or without ZnO. Data were analyzed using PROC MIXED procedures of SAS with treatments as fixed effect and initial BW block as random effect. Orthogonal contrasts were performed to determine the effects of increasing FPM. ADG increased with increasing dietary FPM in pigs fed diets containing ZnO compared to pigs fed diet devoid of ZnO in nursery phase 2 (Linear FPM X ZnO, P < 0.01) & 3 (Quadratic FPM X ZnO, P < 0.05). End BW was higher for pigs fed AP diet when compared to NC (P < 0.01). BW increased with increasing FPM in pigs fed ZnO, while little or no response was observed in pigs fed ZnO free diets (Quadratic FPM X ZnO P < 0.02). Pigs fed 0.25 and 0.50% FPM with ZnO resulted in significantly higher feed intake among all treatments in nursery phase 3 (P < 0.05). During phase 2, increasing the level of FPM increased G:F in pigs fed diets with ZnO (P < 0.001) only. This study validated our previous finding that the growth promoting and intake enhancement effect of FPM in nursery pigs is ZnO dependent.

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.

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.

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.

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)

A field trial was conducted to compare growth responses of 1- to 40-day-old calves to three levels of STEER-oid® implant. A full dose of STEER-oid® consists of 8 pellets and contains 200 mg progesterone, U.S.P., and 20 mg estradiol benzoate, U.S.P. Calves implanted with 1/4 dose (n=35), 1/2 dose (n=30) and a full dose (n=31) were compared with a control group (n=30) receiving no implant. Calves were implanted on October 31, 1984, and December 18, 1984, to meet age restrictions. Mean age at the end of the study was 209 days. Variation in average daily gain (ADG) and final weight (FWT) due to initial weight, initial age, age of dam, sex, sire breed (Charolais vs. Simmental), dam group [Zebu cross (ZX) vs. British and Continental cross (BCX)], implant date and dosage was evaluated. Initial weight and initial age influenced (P

Knowledge of the relationships between scrotal circumference and performance traits can give cattlemen important information for selecting superior sires. Data were collected from 673 individually fed bulls in the University of Arkansas beef-bull performance tests from 1983 through 1986 to evaluate these relationships. Three Arkansas locations, including Fayetteville (1 test/yr), Monticello (1 test/yr), and Hope (2 tests/yr), and 10 breeds were included in the analysis. The dependent variable, scrotal circumference (SC), was analyzed using a model including test number, breed, initial weight (WTI), initial age, backfat thickness (BF), feed conversion (FCONV) and average daily gain (ADG). Scrotal circumference, WTI, BF, ADG, and FCONV were measured in cm, kg, cm, kg and as kg feed/kg gain, respectively. Test number accounted for the variation associated with year, location and season. Breeds evaluated were Simmental (SM), Angus (AN), Hereford (HF), Maine-Anjou (MA), South Devon (SD), Polled Hereford (PH), Charolais (CH), Santa Gertrudis (SG), Brangus (BR) and Beefmaster (BM). Least-squares means indicated that the SM bulls had larger SC (P< .05) than SD, PH, CH, SG, BR, and BM. Conversely, the BM bulls had smaller SC (P< .05) than SM, AN, HF, MA, SD, PH, and CH bulls. The partial regression coefficients of SC on WTI, BF, and ADG were .017, 1.459, and 3.328 cm per unit of measurement, respectively. These data suggest that bulls that are heavier at the start of the test, have higher ADG and greater BF tend to have larger SC.

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)