Feedlot Finishing Research Articles

PSXIII-22 Intake, digestibility, and ruminal parameters of Nellore cattle fed with amylolytic and fibrolytic enzymes in feedlot

Abstract This study was carried out to evaluate the use of dietary exogenous enzyme (ENZ) products with amylolytic and fibrolytic activity on nutrient intake, digestibility, and ruminal volatile fatty acids production (VFA) of Nellore cattle in feedlot. Rumen-cannulated Nellore steers [n = 10; body weight (BW) = 543 kg ± 28.6 BW] were distributed in a replicated Latin-square design (5 × 5) in individual pens. The treatments consisted of a negative control (CON; without ENZ); Amylase (AML; Amaize, Alltech, 0.5 g/kg of DM); Xylanase (FBL, Fibrozyme, Alltech, 0.9 g/kg of DM); Half dose (HD; AML 0.25 g/kg of diet DM and FBL 0.45 g/kg of diet DM); and Full dose (FD; AML 0.5 g/kg of diet DM and FBL 0.90 g/kg of diet DM; Table 1). The experimental period lasted 19 d (14 d of adaptation and 5 d of collection). Between d 15 and 18, total fecal collection was performed and on d 19 rumen fluid was collected at 0, 4, 8, 12, and 16 h post-feeding for ammonia, VFA, and pH determination. The data were analyzed as orthogonal contrasts using SAS: (C1) CON vs. ENZ, (C2) AML vs. FBL, (C3) HD vs. FD, and (C4) AML + FBL vs. HD + FD. There were no C1 differences for nutrient digestibility, total VFA, or ruminal pH (P > 0.10). However, a tendency effect in neutral detergent fiber (NDF) intake (P = 0.065) was observed, where animals fed ENZ had reduced values compared with animals kept in CON group. In the same way, ENZ reduced ther extract (EE) intake (P = 0.023), ruminal ammonia (P < 0.001), and isovalerate proportion (P = 0.080) as well as increased proportion of acetate (P < 0.001), valerate (P < 0.001) and acetate:propionate ratio (P = 0.030). No differences were observed in nutrient intake between AML and FBL (P > 0.10), but AML had greater organic matter (OM) digestibility (P = 0.097) and ruminal valerate (P = 0.039) and decreased butyrate proportion (P = 0.068). Animals that received FD had greater values of dry matter (DM; P = 0.009) and OM (P < 0.001) digestibility than HD. The enzyme combination resulted in greater DM (P = 0.026), OM (P = 0.062), crude protein (P = 0.018), EE (P = 0.063) and NDF (P = 0.040) intake and reduced OM digestibility (P = 0.008) compared with AML and FBL alone. The addition of exogenous enzymes in feedlot diets affected nutrient utilization and ruminal fermentation of Nellore cattle fed a feedlot finishing diet.

125 Could yeast derivatives change beef cattle water intake in different scenarios?

Abstract Adequate water intake is linked to greater dry matter intake, heat loss, and productivity. To measure the water intake of beef cattle reared in groups, two experiments were carried out in Brazil (South East/Middle East) using water throughs coupled with scales (Intergado, Betim, Brazil) and RFID individual identification systems, allowing the recording of individual water intake of animals. In experiment 1, young bulls (n = 96; 105 d on feed - feedlot) were randomly assigned to four treatments: 1) Control, no yeast derivative; 2) AY – 7 g·animal⁻¹·d⁻¹, Autolyzed Yeast grown on sugarcane molasses (RumenYeast, ICC, Brazil); 3) YM – 3 g·animal⁻¹·d⁻¹, yeast rich in soluble Yeast Metabolites; 4) YB – 5 g·animal⁻¹·d⁻¹, Yeast Blend (live Yeast plus autolyzed Yeast). Diets (adaptation, growing, and finishing) x treatments were treated as fixed effects on the complete randomized design. In experiment 2, backgrounding bull calves (n = 32) reared on grazing and 710 g/d of protein supplements (90 d) were randomly assigned to two treatments: 1) Control, no yeast derivative; 2) AY – 7 g·animal⁻¹·d⁻¹, Autolyzed Yeast (RumenYeast), the means were subjected to ANOVA analyses. In both experiments, additives were inserted into the diet (mineral premix or supplement), animals were the experimental unit, and differences were declared significant at P < 0.05. Yeast derivatives increased (P < 0.05) water intake in both experiments (Figure 1). The average increment in water intake (L·animal⁻¹·d⁻¹ was 13.9%. Interestingly, the increment in relation to control was noted for all yeast derivatives and scenarios covered by the experiments (feedlot adaptation diet, feedlot growing diet, feedlot finishing diet, and grazing system). Until now, there seems to be no literature explanation for our findings. However, these results could help to explain the positive effects of yeast derivatives on rumen pH, protein microbial flow, and thermal stress since greater water intake increases the passage rate of rumen fluid and body heat loss. Statistical correlations may not be understood as a cause-consequence link. However, when dealing with a new question, correlations may give us a path to go on and investigate. Malheiros et al. (2023) noted a negative correlation between water intake and rumen dimethylamine. Autolyzed yeast can strongly decrease the concentration of rumen methylamines in cows facing subacute acidosis (Humer et al., 2018). Niacin metabolism should also be investigated since its supplementation enhances cows’ blood niacin levels and water intake. Yeast derivatives are rich in niacin, and autolyzed yeast supplementation can increase blood niacin and body heat loss during summer (Dias et al., 2018), probably increasing water need. In conclusion, yeast derivatives increased the water intake of beef cattle, and this finding adds to the understanding of how yeast derivatives supplementation benefits ruminants.

Profitability, greenhouse gas emissions and feed-food competition of strategies to exploit compensatory growth in Uruguayan weanling-to-beef systems

This study evaluates nutritional and management strategies aimed at exploiting compensatory growth (CG) in weanling-to-beef systems in Uruguay. The evaluation encompassed productivity, economic viability, and environmental impact. The Grange Beef System Model, augmented with Uruguayan national technical coefficients, was used. Four weanling-to-beef systems were modeled: 1) forage only with no CG (FNC), 2) forage only with management improvements to exploit CG (forage with CG; FWC), 3) forage with concentrate supplementation during two winter feeding periods (forage with supplementation; FWS), and 4) forage with supplementation during the first winter followed by feedlot finishing (forage with feedlot; FWF). The systems purchased spring-born Angus calves at 8 months of age and 180 kg live weight (LW) and finished with a slaughter weight of 550 kg. FWS system was used as reference with the performance parameters obtained during 5 years of systems experimentation. FNC used the performance parameters of FWS but during winter periods, LW gain was lower due to the absence of concentrate supplementation. FWC used the previous FNC performance parameters, but increased LW gain after the first and second winter restriction period due to improved grazing management practices thereby exploiting CG. FWF is based on the FWS system but instead of moderate supplementation during the second winter (concentrate: 3.0 kg/d/head), steers are feedlot finished (concentrate: 9.5 kg/d/head) exploiting CG due to previous summer-autumn restriction period. FNC and FWC increased age at slaughter, reducing net beef production by 21 and 11 % relative to FWS, respectively. In contrast, FWF reduced age at slaughter, increasing beef production by 93 % compared to FWS. FWS and FNC had similar profitability expressed in net margin; however, FWC and FWF increased net margin by 33 and 107 % compared to the FWS, respectively. FNC and FWC increased greenhouse gas (GHG) emissions intensity per beef produced by 17 and 3 % relative to FWS, respectively; meanwhile, FWF reduced GHG intensity by 10 % relative to FWS. Due to the inclusion of concentrates in the diet for FWS and FWF systems, the only net producers of human edible energy and protein were the forage-only systems (FNC and FWC). In summary, strategically harnessing CG in both pasture and feedlot finishing stages within a weanling-to-beef system in Uruguay successfully increased profitability. Feedlot finishing reduced GHG emissions per beef produced. However, the forage-only farm systems emerged as the only net producers of human-edible energy and protein.

Pathways toward Climate-Neutral Red Meat Production

Ruminant livestock industries can support the climate stabilization ambitions of the Paris Agreement through interventions that reduce GHG emissions (predominantly biogenic methane) and sequester carbon in landscapes. This study explored pathways for the Australian red meat industry (grazing, feedlot finishing, and domestic processing) to become climate neutral, whereby the radiative forcing (RF) footprint is plateaued and there is no additional forcing contribution. Emissions timeseries (CO2, N2O, CH4) were compiled for 1990 to 2020 and projected to 2030 under a business-as-usual scenario (including an 18% increase in sheep and 13% increase in beef cattle) and with a range of production system and vegetation management interventions. The RF footprint peaked in 2018 at 7.13 mW/m2 and decreased to 7.07 mW/m2 in 2020. With the future expansion of the herd/flock and under business-as-usual conditions, the RF footprint is projected to increase by 2.8% by 2030. However, with a combination of interventions, production has the potential to increase with a decreasing RF footprint, a condition that can be described as climate neutral. The Australian red meat industry has made an historical contribution to global RF increase. However, with ongoing RF management, it is possible to increase food production within climate-neutral limits.

Ruminal Microbiome Differences in Angus Steers with Differing Feed Efficiencies during the Feedlot Finishing Phase.

The catabolic activity of the ruminal microbial community of cattle enables the conversion of low-quality feedstuffs into meat and milk. The rate at which this conversion occurs is termed feed efficiency, which is of crucial importance given that feed expenses account for up to 70% of the cost of animal production. The present study assessed the relationship between cattle feed efficiency and the composition of their ruminal microbial communities during the feedlot finishing period. Angus steers (n = 65) were fed a feedlot finishing diet for 82 days and their growth performance metrics were evaluated. These included the dry matter intake (DMI), average daily gain (ADG), and residual feed intake (RFI). Steers were rank-ordered based upon their RFI, and the five lowest RFI (most efficient) and five highest RFI (least efficient) steers were selected for evaluations. Ruminal fluid samples were collected on days 0 and 82 of the finishing period. Volatile fatty acids (VFA) were quantified, and microbial DNA was extracted and the 16S rRNA gene was sequenced. The results showed that the ADG was not different (p = 0.82) between efficiency groups during the 82-day feedlot period; however, the efficient steers had lower (p = 0.03) DMI and RFI (p = 0.003). Less-efficient (high RFI) steers developed higher (p = 0.01) ruminal Methanobrevibacter relative abundances (p = 0.01) and tended (p = 0.09) to have more Methanosphaera. In high-efficiency steers (low RFI), the relative abundances of Ruminococcaceae increased (p = 0.04) over the 82-day period. The molar proportions of VFA were not different between the two efficiency groups, but some changes in the concentration of specific VFA were observed over time. The results indicated that the ruminal microbial populations of the less-efficient steers contained a greater relative abundance of methanogens compared to the high-efficiency steers during the feedlot phase, likely resulting in more energetic waste in the form or methane and less dietary energy being harvested by the less-efficient animals.

Soil health and root‐zone enrichment characteristics between paired grassland and cropland fields in the southeastern United States

AbstractBackgroundSoil organic C and N data from privately managed pastures in the southeastern United States are relatively scant.MethodsA paired‐farm approach was deployed to determine how a variety of soil health parameters related to nutrient and water cycling might be altered under grazed, botanically diverse perennial pastures compared with annual monoculture croplands in three Major Land Resource Areas of the southeastern United States.ResultsSoil stability index averaged 0.64 and 0.91 mm mm−1 under cropland and grazed pasture, respectively, suggesting that pastures had a more stable soil surface that was resistant to erosion and allowed rapid water infiltration. Surface‐soil organic C and N fractions (i.e., total, particulate, and mineralizable fractions at 0–10 cm depth) were greater under pasture than under cropland. Across locations, root‐zone enrichments (0–30 cm depth) of organic C and N fractions were greater under pasture than under cropland. Within locations, root‐zone enrichment of total soil N was greater (p < 0.05) under pasture than under cropland in the Blue Ridge (2.87 vs. 1.10 Mg N ha−1, respectively) and the Piedmont (2.80 vs. 2.10 Mg N ha−1), but not in the Blackland Prairie (2.40 vs. 2.12 Mg N ha−1).ConclusionsThis study provides evidence that rotationally grazed, perennial grasslands can store more soil organic C and N and improve soil surface stability conditions compared with neighboring croplands producing commodity feed grains for feedlot finishing.

341 Effect of Multispecies Fungal Culture Extract Supplementation on the Growth Performance and Carcass Characteristics of Feedlot Cattle

Abstract To evaluate the effect of supplementing feedlot cattle with a multispecies fungal culture extract (MFE; Aspergillus flavus, Aspergillus niger, Aspergillus oryzae, Aspergillus terreus, Phlebia radiata, Pyricularia oryzae, Stropharia coronilla, Thanatephorus cucumeris, Trichoderma longibrachiatum, Trichoderma reesei, Trichoderma viride) in growth performance and carcass characteristics, Angus × SimAngus-crossbred steers (n = 14) and heifers [n = 46; body weight (BW) 344 ± 21 kg] were used in randomized complete block design. Cattle were blocked by BW and housed in 4 feedlot pens (randomly assigned 2 pens per treatment) where a hay-based diet was fed for 84 d (backgrounding), followed by a ground corn-based finishing diet. Subsequently, cattle were harvested upon reaching desired 12th rib fat thickness (2.0 cm). Diets were offered ad libitum and with (MFE) or without (CON) the inclusion of the multispecies fungal culture extract supplement. Steers were weighed at 28-d intervals throughout the experimental period and carcass data were provided by a USDA grader. All data were analyzed using the PROC MIXED procedure of SAS considering the fixed effect of treatment and sex, and the random effect of block and pen (block). During the 84-d period of the backgrounding phase, feeding MFE increased (P = 0.05, Table 1) the average daily gain (ADG) by ~10%, and tended to increase (P = 0.06, Table 1) the dry matter intake (DMI). No differences were observed in the gain to feed ratio (G:F) between treatments (P = 0.67, Table 1). At the conclusion of the 84-d period, cattle fed MFE were heavier (P = 0.04, Table 1) than cattle in the CON treatment. In the finishing phase, no treatment differences were observed (P ≥ 0.36) for the ADG, DMI, and G:F. At the end of the experiment, cattle supplemented with MFE were heavier (P = 0.04, Table 1) than cattle in the CON treatment. The quantity of days on feed in the finishing diet required to reach harvesting target was not different (P = 0.60) among treatments. For the carcass characteristics, dietary inclusion of the MFE tended to increase the hot carcass weight (P = 0.10, Table 2) and increased the marbling score (P = 0.01, Table 2). No treatment effect was detected (P ≥ 0.25, Table 2) for the dressing, longissimus muscle area, 12th rib fat thickness, kidney-pelvic-heart fat content, and yield grade. Results from this study suggest that dietary inclusion of a multispecies fungal culture extract might improve the growth performance of beef cattle fed forage-based diets, as well as their carcass characteristics after conclusion of the feedlot finishing phase.

PSXI-29 Influence of a Direct Fed Microbial on Growth Performance, Carcass Data, and Immune Function in Feedlot Finishing Steers

Abstract One hundred and eighty crossbred beef steers (405.9 ± 2.3 kg) were used to determine the impact of a direct fed microbial (DFM) on growth performance, carcass characteristics, and immune response in finishing beef cattle. Steers were blocked by body weight and randomly assigned, within block, to 1 of 2 treatments (3 replicates/treatment: 30 steers/replicate). Groups within a replicate were randomly assigned to treatments. Treatments included: 1) no DFM (control) and 2) DFM supplementation at 50 mg/animal/d [BOVAMINE DEFEND Plus containing Lactobacillus animalis, Propionibacterium freudenreichii, Bacillus licheniformis, and Bacillus subtilis]. All steers were fed a high concentrate, steam-flaked corn-based finishing diet. Individual feed intake was recorded daily via the GrowSafe system. Body weights were collected every 28 d. Jugular blood samples were collected from all steers on day 0 and 112. On d 55 of the experiment, 10 steers per pen (30 steers per treatment) were randomly selected and injected, subcutaneously with 4.0 mg of ovalbumin (OVA). Jugular blood samples were collected from each steer on d 0, 7, 14, and 21 post injection. On d 112 of the experiment, the same steers were injected with the same dose of OVA and intramuscularly with 5 mL of a 25 % pig red blood cell (PRBC) solution. Jugular blood samples were collected from each steer on day 0, 7, 14, and 21 post injection. After receiving the finishing diet for 185 d, cattle were transported to a commercial abattoir and slaughtered. Hot carcass weights were collected at the time of slaughter. Carcasses were allowed to chill for 24 h before carcass data were collected. Data were analyzed as a completely randomized block design and individual animal within pen was considered the experimental unit. Initial body weight, final body weight, and overall feed efficiency were similar across treatments. Steers receiving DFM had greater (P < 0.01) body weights and average daily gains on d 28 and 55 and greater (P < 0.04) dry matter intakes over the entire experiment compared with controls. Hot carcass weight, longissimus muscle area, quality grade, and marbling score were similar across treatments. However, dressing percentage (P < 0.02) was greater in steers receiving DFM compared with controls. Antibody titers to OVA and PRBC and d 112 interferon gamma concentrations were similar across treatments. However, red blood cell superoxide dismutase activity was greater (P < 0.05) in DFM-supplemented cattle compared with controls on d 112 of the experiment. These data suggest that BOVAMINE DEFEND Plus supplementation improves growth performance during certain periods of the finishing phase, increases overall dry matter intake and carcass yield, and may impact antioxidant status in beef cattle.

176 Relationships Among Early Life Weight and Growth Among Halfblood Bos Indicus Male Calves and Associations with Carcass Weight

Abstract Nellore-Angus steers (n = 572) born in 2009-2013, 2015, and 2019 and Brahman-Angus reciprocal steers (n = 73) born in 2019 and 2020 were evaluated for calf and carcass weights (HCW). Calves were born and reared at the McGregor Research Center and included F2, F3, F4, and F5 Nellore-Angus and F1 Brahman-Angus. Calves were weighed at 4 approximate times: within 48 h of birth (BWT), 50 d age (spring-working, SWWT, not available for 2009-2010), 180 d age (pre-weaning, PRWWT), and approximately 210 d age (weaning, WWT). Animals born in the same year were managed similarly, and cow herds were managed together in most cases except during annual natural service, multi-sire breeding seasons. Animals born in the same year were managed as contemporaries post-weaning and for feedlot finishing. Mixed model analyses of variance for calf traits included genetic type (nested within calf birth year), calf birth year, age of dam category, and covariates of Julian birth date (BWT, SWWT) or calf age (PRWWT and WWT) as fixed effects. In each year at least 2 genetic types were present; however, because of imbalance across years, only genetic types produced in the same years were compared following significant F-tests. For these analyses cow age category did not affect calf BWT or SWWT, but showed influence for PRWWT (P = 0.006) and WWT (P < 0.001); cow age category did not affect calf ADG. Differences in calf weights (P < 0.001) and calf ADG (P < 0.001) due to the genetic type were driven by reciprocal differences between Brahman-Angus crosses and potential maternal hybrid vigor advantages for F2 Nellore-Angus calves from F1 dams vs. other genetic types. Brahman-sired F1 (B × A) males were 12.7 to 14.1 kg heavier for BWT (P < 0.001) and 14.9 to 19.2 kg heavier for SWWT (P < 0.001) than Angus-sired F1 males (A × B), but persistence to weaning varied across years. It appears in these data that some genetic types may be more sensitive to individual year effects, but it is uncertain why. Correlations of calf weight traits with HCW were inconsistent across genetic types. No calf weight was associated with HCW in A × B crosses, and only PRWWT in B × A related to HCW (r = 0.44, P = 0.007). Among Nellore-Angus crosses, BWT showed small to moderate correlation to HCW (0.23 < r < 0.46); however, among the F4 and F5 calves, later weights (SSWT, PRWWT and WWT) had large correlations with HCW (0.50 < r < 0.79) whereas these correlations ranged from 0.24 to 0.37 in F2 and F3 steers. It appears animals of similar Bos indicus percentage may have quite different calf growth patterns related to HCW.

227 Evaluation of Beef Cattle Performance on Nontraditional Beef Cattle Finishing System Compared with Traditional Beef Cattle Finishing System

Abstract While much research exists examining finishing cattle in conventional systems (confined cattle feeding, or feedlot systems), few data exist regarding finishing cattle in non-traditional systems, particularly in the micro-climates of the Gulf Coast. Non-traditional finishing systems feature additional variables and complexities versus feedlot finishing. The objective of this trial was to compare two non-traditional low input finishing cattle programs with a greater input traditional cattle finishing management program. Crossbred beef heifers [n = 12, initial body weight (BW) = 400 kg] were used to evaluate performance and cost of finishing beef cattle on limit-fed supplemental rations (CORN and SBH) compared with a totally mixed, free-choice ration (DIET). Animals were blocked by BW and randomly allotted to three treatments (CORN, n = 4; SBH, n = 4 and DIET n = 4). Two limit fed diets were combinations corn and a protein based mixing pellet (CORN) or soyhulls and a protein based mixing pellet (SBH), both fed at the rate of 1.9% of BW, while providing the heifers with free-choice access to bahiagrass (Paspalum notatum) forage during the summer months; DIET was a more conventional total mixed ration that provided both the concentrate and roughage component and included corn, soyhull pellets, mixing pellet, and cotton gin motes. Cattle were finished for 132 (n = 6) or 174 d (n = 6) and harvested at the MSU Meat Laboratory in Starkville located 235 miles from the trial location. Data were analyzed using MIXED procedure of SAS By design, dry matter intake during the entire finishing phase was greater (P = < 0.0001) for the free-choice DIET (10.8 kg. per day), compared with the limit fed diets (8.5 and 8.4 kg. per day). Overall average daily gain (ADG) was similar (P= 0.10) between both limit-fed diets (0.99 and 0.98 kg. per day for CORN and SBH). Average daily gain of cattle fed DIET (1.14 kg. per day) tended to be greater (P < 0.06) than both CORN and SBH diets. No differences were noted in G:F at any point during the study (P > 0.20). No differences (P > .0.05) were evident for slaughter weight, hot carcass weight, shrink, and dressing percentage among treatments. Total cost of gain for CORN and SOY were $1.74 and $1.65 cents per kilogram compared with DIET of $1.74 cents per kilogram (P = 0.76). Results indicate limit fed CORN and SBH diets could be a viable option to finish beef just as efficiently as a greater roughage total mixed ration (DIET).

Metabolic profile of goats fed diets containing crude glycerin from biodiesel production.

Feedlot finishing of goats is a growing practice, but the economic viability of this technology is compromised by the inclusion of ingredients such as corn and soybean. An alternative to minimize this barrier is the use of agroindustry coproducts as substitutes for those ingredients, such as crude glycerol. This study aimed to evaluated the metabolism of crossbred Boer finishing goats fed diets containing crude glycerin from biodiesel production. Thirty-two crossbred, castrated goat of age were distributed in a fully randomized experimental design with four treatments and eight replicates. The experiment lasted 69 days, and goats were fed sorghum silage and concentrate, with the inclusion of crude glycerin in the diet at levels of 0, 50, 100, and 150 g/kg on a dry matter basis. The diets did not have an effect (p > 0.05) on the serum urea levels. Increasing dietary crude glycerin levels did not the influence the metabolic or urinary profiles (p > 0.05). The liver tissue of the goats fed diets containing the highest crude glycerin inclusion levels showed deleterious effects. The inclusion of crude glycerin with approximately 6.6 g/kg methanol caused deleterious effects to the liver tissue of Boer crossbred goats as the glycerin concentrations increased. However, glycerin levels did not cause deleterious effects on the liver tissue or on the serum or urinary profiles. The use of crude glycerin with lower methanol content is recommended for goat diets.

Muscle proteome of crossbred cattle that received vitamin A at birth: impacts on meat quality traits

This study aimed to evaluate the skeletal muscle proteome of calves that received an intramuscular application of vitamin A at birth and its impacts on meat quality. Forty male crossbred calves were used from birth to feedlot finishing. On the day of birth, 20 calves were injected intramuscularly with a single dose of 300,000 IU of vitamin A and the other 20 animals received placebo (control). After weaning at 210 days, the animals of the two treatments were feedlot finished for 180 days. Longissimus muscle samples were collected for proteome analysis and meat quality assessment. There was a trend (P = 0.07) towards more tender meat in animals that received vitamin A compared to control (WBSF = 3.92 ± 0.16 kg vs. 4.23 ± 0.15). Meat color, pH and cooking loss were not affected (P > 0.05). Vitamin A treatment resulted in a more than 50% increase in intramuscular fat (IMF) content (P < 0.05) compared to control (4.10 ± 0.35% vs. 2.57 ± 0.27%). The intramuscular injection of vitamin A affected the post-mortem muscle proteome and the protein-protein interactions. A greater abundance of proteins involved in three main pathways were observed these being energy metabolism (GAPDH, ENO3, TPI1, CKM, and COX5A), muscle contraction (ACTB, ACTC1, ACTG1, ACTG2, ACTA1, ACTA2, ACTN1, ACTN2, ACTN3, TPM1, TPM2, TPM3, MYH1, PDLIM3, and TNNT3), protein binding, transport, and signaling (TUBA4A, VIM, TBA1B, and EEF1A2). A greater abundance of oxidative stress and cellular defense proteins (HSPA8 and DNAJC18) was specifically observed in the control treatment. Vitamin A upregulated key biological processes related to energy metabolism, which favored IMF accumulation during the finishing phase.

P63 Effect of the inclusion of pasture in feedlot finishing diet of Holstein steers on meat quality and fatty acid profile

P63 Effect of the inclusion of pasture in feedlot finishing diet of Holstein steers on meat quality and fatty acid profile

Feeding Management Strategies to Mitigate Methane and Improve Production Efficiency in Feedlot Cattle

Mitigation of greenhouse gases and decreasing nutrient excretion have become increasingly important goals for the beef cattle industry. Because feed intake is a major driver of enteric CH4 production and nutrient excretion, feeding management systems could be important mitigation tools. Programmed feeding uses net energy equations to determine the feed required to yield a specific rate of gain, whereas restricted feeding typically involves decreasing intake relative to the expected or observed ad libitum intake. In the context of growing/finishing systems typical of those in the United States and Western Canada, experimental results with programmed and restricted feeding have often shown decreased overall feed intake and increased gain efficiency relative to ad libitum feeding, but too much restriction can negatively affect harvest weight and associated carcass quality. Slick feed bunk management is a time-based restriction that limits day-to-day variation in feed deliveries, but the effects on intake and performance are not well defined. Simulations to estimate enteric CH4 emission and nitrogen excretion indicated that programmed feeding of a high-grain diet could appreciably decrease CH4 emissions and nitrogen excretion compared with traditional growing programs based on high-forage diets. For feedlot finishing, programming gain for a portion of the feeding period will decrease CH4 emission and N excretion only if cattle perform better than expected during the programmed phase or if compensatory growth occurs when cattle are transitioned to ad libitum feeding. Optimal approaches to implement programmed or restricted feeding that will yield increased efficiency should be the subject of future research in this area.

186 Effect of Feedlot Finishing Compared with Grass fed Beef Following Bale Grazing and Delayed Feedlot Entry on Steer Performance, Carcass Measurement and net Return

Abstract In a grass-fed system grazing study, yearling crossbred Aberdeen Angus x Red Angus x Angus x Angus steers (n = 72; 3 reps/8 steers/rep) were assigned to either a grass-fed annual forage (GFANN) or a grass-fed native range (GFNR) system, and compared with a NR feedlot control system (FLT), in a delayed feedlot entry program, to determine the effect of grazing and feedlot finishing performance, carcass measurements, and systems net return. Data were analyzed using the MIXED procedure of SAS. After 176.0 grazing days, GFANN, GFNR, and FLT steers were transitioned to free-choice cover crop hay bale feeding (BGRZ) and 3.09 kg daily of a wheatmidd-based supplement (SUP). GFANN and GFNR received hay and SUP for 92 d; FLT control steers received hay and SUP for 69 d before transfer to the University of Wyoming feedlot. Grass-fed and FLT steers were harvested at federally inspected abattoirs in Green Bay, WI, and Ft. Morgan, CO, respectively. BGRZ gain and ADG for GFANN and FLT were greater than GFNR (P = 0.075; P = 0.072). When GFANN and GFNR bale grazing finishing costs were combined with FLT cost, feed cost/unit of gain were greater for GFANN and GFNR compared with FLT (P = 0.006). Steer FLT HCW was 26% and 34% heavier (P = 0.001), marbling score was 32% and 38% greater (P = 0.001), and carcass value was 16% and 24% greater (P = 0.001) than GFANN and GFNR, respectively. Net return was -$88.25, $62.70, and $160.22 for GFANN, GFNR, and FLT, respectively. Farming and long-haul transportation cost for GFANN and GFNR negatively affected net return.

PSVII-10 Effects of Supplementing a Standardized Plant-Derived Feed Additive Containing Isoquinoline Alkaloids on Rumen Lesions in Feedlot Cattle

Abstract Long-term feeding of high grain diets can lead to digestive disorders which can result in inflammation of the digestive tract, poor performance and a negative impact on animal welfare. Plant-derived feed additives are widely used in food producing animals to improve the productivity, digestibility, and health. The objective of the present study was to assess the effects of supplementing a plant-derived feed additive containing standardized concentrations of isoquinoline alkaloids (IQ) on rumen lesions in finishing feedlot cattle. Crossbreed bulls from a commercial feedlot were enrolled in the present study. During the control period (CON; n = 470): from September 1st to October 12th cattle were fed the feedlot finishing diet. During the treatment period (TRT; n = 480): from October 13th to November 23rd finishing feedlot cattle were fed the same ration plus 600 g/t of a feed additive with standardized concentrations of IQ. Slaughter was performed in 2 abattoirs and the rumen of animals were examined by the same investigator. Rumen health was scored by visual observation of the rumen epithelia: 1) normal rumen; 2) mild rumenitis; 3) moderate rumenitis; 4) diffuse rumenitis 5) ulcerative rumenitis. Statistical analysis was performed with the R software. The Pearson chi-squared statistic was performed to test the independence between the variables. Results showed that TRT had greater and positive association with score 2 (P&amp;lt; 0.05; 3.2), and a negative association (P&amp;lt; 0.05) with scores 4 (-1.1) and 5 (-1.1). The CON presented greater and positive association with score 3 (P&amp;lt; 0.05; 3.3), as well as positive association (P&amp;lt; 0.05) for the scores 4 (1.1) and 5 (1.1). In conclusion, supplementing finishing feedlot cattle with a plant-derived feed additive containing IQ resulted in less severe rumen lesions in feedlot cattle receiving finishing diets indicating that IQ exerted a positive effect on rumen condition.

Fortification of diets with omega-3 long-chain polyunsaturated fatty acids enhances feedlot performance, intramuscular fat content, fat melting point, and carcass characteristics of Tattykeel Australian White MARGRA lambs.

Meat eating quality indices such as intramuscular fat content (IMF) and fat melting point (FMP) of the Longissimus thoracis et lumborum muscle and the feedlot performance, carcass traits, and commercial wholesale cuts of lot-fed Tattykeel Australian White (TAW) MARGRA lambs as a result of dietary fortification of the diet with omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) were evaluated. A total of 75 TAW MARGRA lambs at 6 months of age with an average liveweight of 30 ± 1.2 kg were used. The lambs were randomly allocated to the following three dietary treatments of 25 lambs each in a 47-day feeding trial using a completely randomized experimental design: (1) control diet of hay plus pellets without omega-3 oil, (2) hay plus commercial whole grain pellets (MSM) without omega-3 oil, and (3) hay plus pellets fortified with omega-3 oil. It was hypothesized that dietary supplementation with omega-3 fortified pellets will improve feedlot performance, meat-eating quality indices of IMF, FMP, and carcass characteristics. Lot-fed lambs on the MSM whole grain had the highest feed intake of 1.69 kg/day, followed by the control at 1.57 kg/day and the lowest in the omega-3 diet at 1.01 kg/day (p = 0.0001). However, the omega-3 diet had the highest average daily gain of 230 g/head/day (p = 0.0001), indicating the greatest feed efficiency since it had the best growth response with minimal feed intake. Post-slaughter evaluation of the Longissimus thoracis et lumborum muscle revealed significant treatment variations in IMF (p = 0.0001), FMP (p = 0.0001), pH (p = 0.0380), and wholesale French rack primal cut (p = 0.0001). Strong correlations (p < 0.05) between liveweight, temperature, pH, FMP, and IMF were observed. Similarly, significant correlations between carcass characteristics of total saleable meat yield, lean trim, fat trims, bones, and leg shank were evident (p < 0.05). However, there were no treatment differences in the final liveweight, GR fat depth, hot standard carcass weight, or dressing percentage. The findings indicate that feedlot performance, meat-eating quality traits such as IMF and FMP, and commercial wholesale French rack cuts can be further improved during feedlot finishing of TAW MARGRA lambs through dietary supplementation with omega-3 oils, and hence the tested hypothesis of improved meat quality attributes is partially confirmed.

Evaluation of the effects of wood-sourced biochar as a feedlot pen surface amendment on manure nutrient capture.

Feedstuffs utilized in U.S. feedlot finishing rations incorporate high concentrations of N and P, with less than 15% of fed N and P retained by the animal. The remaining N and P are excreted in the manure, where the opportunity for manure N loss via ammonia (NH3) volatilization from the feedlot pen surface is a risk to the environment and lowers the value of manure as a fertilizer. Two nutrient mass balance experiments were conducted during the winter and summer seasons to evaluate the effects of spreading unprocessed Eastern red cedar biochar onto the feedlot pen surface on manure nutrient capture and cattle performance. A 186-d feedlot finishing experiment was conducted from December to June (WINTER) and a subsequent 153-d finishing experiment was conducted from June to November (SUMMER). The WINTER experiment evaluated three treatments (5 pens per treatment; 10 steers per pen), including biochar spread on pen surface during the feeding period (1.40 kg biochar/m2; 17.6 m2/steer soil surface of the pen), hydrated lime spread on pen surface at end of feeding period (1.75 kg/m2) and control (no treatment applied). The SUMMER experiment evaluated biochar treatment (1.40 kg biochar/m2; 5 pens per treatment; 8 steers per pen; and 22 m2/steer soil surface of the pen) against control. There were no differences in N and P intake, retention, or excretion (P ≥ 0.38) between WINTER treatments. Steer performance (P ≥ 0.10) and carcass characteristics (P ≥ 0.50) were not impacted by pen treatment in WINTER. Nitrogen and P intake and excretion (P ≥ 0.35) were not different between treatments in SUMMER and retention of N and P was significantly greater for the biochar treatment (P ≤0.04) due to greater ADG (P = 0.05). There was no difference in DMI (P = 0.48) in SUMMER, steers on biochar pen treatment had heavier HCW (P = 0.05) and greater ADG, resulting in a tendency for greater feed efficiency (P = 0.08). In both experiments, biochar addition to the pen surface tended (P = 0.07) to increase manure N as a percent of manure DM, but this increase in N concentration did not impact kg of N removed from the feedlot pens (P ≥ 0.15) or N losses (P ≥ 0.68). The addition of red cedar biochar to the feedlot pen surface did not increase manure nutrient capture of N or P and did not reduce N losses associated with soil-based feedlot pens.

Comparing the responses of grain fed feedlot cattle under moderate heat load and during subsequent recovery with those of feed restricted thermoneutral counterparts: plasma biochemistry

Responses to heat stress in ruminants reflect the integration of local climatic conditions, environment/production system and the animal's homeostatic and homeorhetic capacities. Thus, the goal of ameliorating heat stress requires experimental settings that, within limits, closely resemble the target production system and cohort. We investigated the blood biochemical changes of two sequential cohorts of twelve 518 ± 23kg grain fed Black Angus steers. Each cohort consisted of two treatments of 6 head/group: a thermally challenged (TC) treatment and a feed restricted thermoneutral (FRTN) treatment. Both groups were housed in climate controlled rooms for 19days, with the TC group experiencing three distinct periods: PreChallenge, Challenge and Recovery. PreChallenge and Recovery delivered thermoneutral conditions, while Challenge consisted of 7days of moderate diurnal heat load. The FRTN group was maintained in thermoneutral conditions at all times. Both groups were then relocated to outdoor pens for a further 40days to detect any enduring change to metabolism as a consequence of the treatments. We compared blood biochemical responses of the treatments and inferred likely metabolic changes. Relative to the FRTN group, the TC animals experienced limited supply of triglycerides, cholesterol and glutamine during moderate heat load, suggesting constraints to energy metabolism. Lower blood urea during Recovery and in outdoor pens implied a requirement to capture N rather than allow its excretion. Altered liver enzyme profiles indicated a higher level of hepatic stress in the TC group. By the completion of feedlot finishing, the groups were not separable on most measures.

Liver abscess microbiota of feedlot steers finished in natural and traditional management programs.

Liver abscess etiology in feedlot steers involves the escape of bacteria from the digestive tract to form a polymicrobial abscess within or on the external surface of the liver. However, little is known about the effects of feedlot finishing systems on the microbial composition of the liver abscess purulent material. Liver abscesses were collected at the time of harvest from steers originating from a single feedlot managed in either a traditional program (which included tylosin phosphate supplementation) or a natural program (without tylosin phosphate supplementation). The purulent material of liver abscesses from traditionally managed steers (N = 53 abscesses) and that of naturally managed steers (N = 62 abscesses) was characterized using the V4 region of the 16S rRNA gene. Two phyla and three genera were found in greater than 1% relative abundance across all abscesses. The genus Fusobacterium was identified in all liver abscess samples and accounted for 64% of sequencing reads. Bacteroides and Porphyromonas genera accounted for 33% and 1% of reads, respectively. Trueperella was more likely to be found in the liver abscesses of naturally managed steers than traditionally managed steers (P = 0.022). Over 99% of the genus-level bacterial sequences observed across all liver abscesses belonged to Gram-negative genera. Bacteria known to colonize both the rumen and hindgut were identified within liver abscesses. No differences in alpha diversity or beta diversity were detected between liver abscess communities (between the two management programs or individual pens) when tested as richness, Shannon Diversity Index, or weighted UniFrac distances (P > 0.05). These results were consistent with previous identification of Fusobacterium necrophorum as the primary bacteriologic agent within liver abscesses and emphasized the relationship between the gastrointestinal microbiota and liver abscess formation. Though the microbiota of the liver abscess purulent material was similar between steers fed an antibiotic-free diet and those fed an antibiotic-containing diet from the same feedlot, divergence was detected in liver abscess communities with some being dominated by Fusobacterium and others being dominated by Bacteroides.