Effects of feeding lubabegron on gas emissions, growth performance, and carcass characteristics of beef cattle housed in small-pen environmentally monitored enclosures during the last 3 mo of the finishing period

The development of technologies that promote environmental stewardship while maintaining or improving the efficiency of food animal production is essential to the sustainability of producing a food supply to meet the demands of a growing population. As such, Elanco (Greenfield, IN) pursued an environmental indication for a selective β-modulator (lubabegron; LUB). LUB was recently approved by the United States Food and Drug Administration (FDA) to be fed to feedlot cattle during the last 14 to 91 d of the feeding period for reductions in gas emissions/kg of unshrunk final BW and HCW. A 4 × 2 factorial arrangement of treatments was used with the factors of dose (0.0, 1.38, 5.5, or 22.0 mg·kg⁻¹ DM basis) and sex (steers or heifers). Three 91-d cycles were conducted (112 cattle/cycle) with each dose × sex combination being represented by a single cattle pen enclosure (CPE; 14 cattle/CPE) resulting in a total of 168 steers and 168 heifers (n = 6 replicates/dose). There were no interactions observed between dose and sex for any variable measured in the study (P ≥ 0.063). Five gases were evaluated for all pens based on CPE concentrations relative to ambient air: NH₃, CH₄, N₂O, H₂S, and CO₂. Cumulative NH₃ gas emissions were reduced by feeding cattle 5.5 and 22.0 mg·kg⁻¹ LUB (P ≤ 0.023) and tended (P = 0.076) to be lower for the cattle fed 1.38 mg·kg⁻¹ LUB compared with the negative controls (CON). The cumulative NH₃ gas emission reductions of 960 to 1032 g, coupled with HCW increases (P ≤ 0.019) of 15 to 16 kg for all LUB doses vs. CON, led to reductions in NH₃ gas emissions/kg HCW for all three LUB treatments (P ≤ 0.004). Similar to HCW, reductions in NH₃ gas emissions/kg of unshrunk final BW were observed for all LUB doses (P ≤ 0.009) and were attributable to both decreases in NH₃ gas emissions and numerical increases in BW. Dose had no effect on cumulative emissions or emissions standardized by BW or HCW for the other four gases (P ≥ 0.268). LUB is a novel tool to reduce emissions of NH₃ gas per kilogram of unshrunk live BW and hot carcass weight.

PSIII-10 The Effect of Sire Line on Grow-finish Performance, Carcass Characteristics, and Meat Pricing Variables for Commercial Crossbred Pigs

The objective of this study was to evaluate the effect of sire line on wean-to-finish performance, carcass characteristics, and meat pricing variables. Pigs used for this study were the progeny of a commercial Landrace x Large White female mated to one of the following sire lines: a purebred Duroc line (Line S1), or a synthetic (Line S2) or purebred Duroc line (Line S3) originating from a different genetic source. An equivalent number of pigs (n =144) were used per group, for 432 pigs placed on test. Average initial weights per line were 6.67 ± 0.24, 6.67 ± 0.24, and 6.60 ± 0.24 for lines S1, S2, and S3, respectively. At placement, 8 pigs were assigned to each pen (split sex) and blocked by line and initial BW, with 18 replicates per line. Data were analyzed at the pen level using the PROC MIXED procedure of SAS, where the effects of line, sex, and line*sex were fitted as fixed effects and replicate was fitted as a random effect. Overall, piglets from line S2 (0.403 vs 0.381; P ≤ 0.0004) and line S3 (0.402 vs 0.381; P ≤ 0.001) had improved GF compared with piglets from line S1. The ADFI was greater in piglets from line S1 relative to piglets from line S2 (2.264 vs 2.117 kg; P ≤ 0.0001) and line S3 (2.264 vs 2.159 kg; P ≤ 0.004). The ADG, HCW, dressing yield, and loin depth were not different among treatment (P > 1.00). Piglets from line S3 had greater percent lean (57.12 vs 56.29 %; P ≤ 0.0001) and better carcass grade premium ($7.07 vs 6.60; P ≤ 0.0291) relative to piglets from line S1. In conclusion, line S1 piglets had greatest ADFI, but line S2 pigs and line S3 piglets had better feed efficiency. Line S3 pigs were leaner and had better carcass grade premium.

PSIII-9 The Effect of Sire Line on Reproductive Performance During Lactation

The objective of this study was to estimate the effect of sire line on sow and piglet performance during lactation. Commercial Landrace x Large White females (n = 60) were bred to one of the following sire lines: a purebred Duroc line (Line S1), a synthetic (Line S2), or purebred Duroc (Line S3) from a different genetic source. Matings were balanced by line and parity. Females were fed a common gestation and lactation diet during these respective phases. Sow and piglet data were analyzed as a completely randomized design using the GLM procedure of SAS. Results show that, during lactation, females bred to line S3 lost significantly (P = 0.01) more BW (-16.93 ± 3.56 kg) than females bred to line S2 (-2.00 ± 3.50 kg). However, no evidence of a difference (P = 0.18) in BW loss was detected between females bred to line S3 (-16.93 ± 3.56 kg) vs. Line S1 (-7.90 ± 3.56 kg). Further, sows bred to line S3 weaned significantly (P = 0.03) more piglets (12.0 ± 0.28) than females bred to line S2 (10.9 ± 0.27), but not (P = 0.1) compared to females bred to line S1 (11.7 ± 0.27). No significant effect of line (P > 0.05) or parity (P > 0.05) on total number of piglet’s born, number born alive, number of stillborn piglets, or preweaning mortality was detected. The number of mummified fetus tended to be lower in line S2 (0.17 vs 0.66; P = 0.079) and line S3 (0.12 vs 0.66; P = 0.051) sows compared with line S1 sows, respectively. In conclusion, sire line did not have a significant effect on total number born, number born alive, number stillborn, or preweaning mortality. However, females bred to line S3 lost significantly more BW during lact but weaned significantly more piglets than females bred to line S2.

41 Characterizing the amount and variability of intramuscular fat deposition throughout the loin using barrows and gilts from two genotypes

Pork quality is evaluated by commercial processors along the ventral surface of whole boneless loins. However, in retail settings boneless chops are evaluated individually for quality. The objective was to determine the variability in marbling attributable to chop location, sex, and sire line. The population of pigs evaluated were sired by commercial duroc boars selected for meat quality (MQ; n=96) or lean growth (LG; n=96) and equally split between sexes. Upon slaughter and fabrication, bone-in chops were removed from four locations along the loin (A=6th rib, B=10th rib, C=last rib, D=4th lumbar). Pairs of chops from each location were used for visual color, visual marbling, and subjective firmness, Warner-Bratzler shear force, and determination of moisture and extractable lipid (IMF). Variability across location, sex, and sire line was measured using a Levene’s test and the VARCOMP procedure of SAS was used to evaluate the proportion of variability each contributed to total variance. Barrows produced chops with greater IMF (3.64%) and variability (P< 0.001) than gilts (3.20%; P< 0.001). Chops from MQ pigs exhibited greater IMF (4.02%) and variability (P< 0.001) than LG (2.82%; P< 0.001). Chops from location A (3.80%) and D (3.77%) had greater IMF than B (3.34%; P< 0.001) with all three locations greater than C (2.77%; P< 0.001). Variance (s2) also differed (A=1.44% B=1.59% C=1.05% D=2.18%; P< 0.05) across chop locations. Of the variability in IMF, 33.0% was attributed to sire line, 10.16% to chop location and 4.01% to sex, with 52.83% unaccounted for. Location A chops were the most tender (2.57kg; P< 0.001) and C chops the least tender (2.93kg; P< 0.01). No differences in variability (s2; P=0.40) of tenderness were observed across chop location (A=0.31kg B=0.24kg C=0.24kg D=0.23kg). In conclusion, chop location, sex, and sire line all contribute to the amount and variability of pork loin marbling. Supported by National Pork Board Grant #18-118.

Evaluation of Variability of Instruments Used in Pork Loin Quality Assessments

ObjectivesIt has been historically proven that when measuring instrumental color, the magnitude of the color value will differ between instruments types, (i.e., HunterLab and Minolta). However, it is not known whether variability of readings within machine differs between machine type when measuring instrumental color or pH. It is also not known if pH or color values from one machine can be used to predict values from a second machine. The objectives were to (1) evaluate the effect of machine on the variability of instrumental color and pH measurements of boneless pork loins and (2) determine if color or pH measurements from one machine type can be used to predict measurements from a second machine type.Materials and MethodsTwo different sets (n1 = 253 and n2 = 294, respectively) of loins from a commercial processing facility were measured for instrumental color analysis. Loins were evaluated on the ventral face at the approximate location of the 10th rib at 22 h postmortem. Instrumental color was measured using a Minolta CR-400 Chroma meter equipped with a D65 illuminant, 2° observer, 8mm aperture, and calibrated with a white tile specific to the machine, but the first set were measured with an open aperture while the second used a closed aperture. The HunterLab was equipped with a 10° observer, 25 mm port and calibrated with a black and white tile specific to the machine for both sets. Ultimate pH was measured on three additional sets of loins (n1 = 249, n2 = 170, and n3 = 285 for each group, respectively) using two separate pH meters. Color and pH data were analyzed using the MIXED procedure of SAS as a 1-way ANOVA with two levels (Minolta and Hunter for color, Meter A and Meter B for pH). Variances for each treatment were calculated using the means procedure and tested for homogeneity using the Levene’s test of the GLM procedure. Means and variances were considered different at P ≤ 0.05. Coefficients of determination (R2) were calculated using the REG procedure between Hunter and Minolta readings and between pH meters.ResultsRedness, Chroma and hue angle had greater variability (P < 0.01) when measured using the open aperture Minolta than HunterLab, while only chroma (P = 0.04) and hue angle (P < 0.01) had greater variability when using the closed aperture Minolta compared with the HunterLab. Variability of other traits did not differ between machines. For each set of loins, pH variability was greater for meter B than meter A. R2 values between the HunterLab and open aperture Minolta were 0.42 for lightness, 0.41 for redness, 0.27 for yellowness, 0.28 for saturation, and 0.18 for hue angle. R2 values between the HunterLab and closed aperture Minolta were 0.42 for lightness, 0.42 for redness, 0.33 for yellowness, 0.24 for saturation, and 0.04 for hue angle. Meter A was able to predict between 17–21% of variation in Meter B.ConclusionOverall, variability was generally not different between color machines, while pH meters had different variabilities between machines and on days of measurement. Neither color instruments nor pH meters were able to predict values from other instruments of different types well enough for practical use.