Combination of carbohydrases and essential oils improve dietary performance of feedlot steers on a high-energy diet

Essential oils and enzymes are alternatives to feed additives for ruminants that aim to replace the use of ionophores and improve animal performance, but their mechanisms of action are different. Therefore, the present study aimed to verify if there is a synergistic effect in the combined use of enzymes carbohydrates and essential oils on the performance, ingestive behavior and carcass traits of steers fed a high-energy diet. During the finishing period of 78 days, 40 steers were assigned to four treatments: CON- control; ENZ- enzymatic complex; EO- essential oil blend; ENZ+EO - enzymatic complex combined with essential oil blend. Regardless of the feedlot periods, the ENZ+EO treatment caused a reduction in the dry matter intake (12.48%) compared to the control. The ENZ+EO treatment resulted in the lowest mean fecal output and, consequently, the highest dry matter digestibility (DMD) and starch digestibility (SD), compared to the other treatments. Animals that received EO and ENZ+EO in the diet spent more time in feeding. As for the number of times animals visited the feeding trough, the highest values were presented by the animals in the EO, ENZ and ENZ+EO treatments. For the carcass parameters, only the subcutaneous fat thickness on the rib was significantly different between treatments, with the highest values obtained by adding EO and ENZ+EO (8.80 and 8.10 mm respectively). Thus, the combination of carbohydrate enzymes and essential oils proved to be synergistically beneficial in relation to better use of nutrients and productive performance of feedlot steers.

Effect of Fresh Citrus Pulp Supplementation on Animal Performance and Meat Quality of Feedlot Steers

The use of fruit by-products such as citrus pulp represents a feeding ingredient that deserves to be evaluated as an energy source in animal rations. Thirty-six British breed steers were allotted to one of the three feeding treatments (12 steers/treatment): 0%, 15% and 30% of fresh citrus pulp inclusion in the ration in a randomized complete block design to evaluate animal performance and carcass and meat quality traits. In the present study, the inclusion of fresh citrus pulp up to 30% of the diet did not affect the animal average daily gain (p > 0.05) but steers that were fed the pulp consumed less feed (p < 0.05) and presented a lower feed conversion ratio (p < 0.05) than their counterparts without citrus pulp in their diet. No effect of fresh citrus pulp was observed on carcass and meat quality (p > 0.05). A greater lipophilic antioxidant capacity (p < 0.05) in meat was observed when fresh citrus pulp was offered at 15% of the diet. Fresh citrus pulp used up to 30% as a feed ingredient in feedlot rations does not negatively affect animal performance or meat quality but, rather, has a positive effect on dry matter intake and a better feed conversion ratio.

Evaluation of reticulorumen temperature boluses for the diagnosis of subclinical cases of bovine respiratory disease in feedlot cattle

Bovine respiratory disease (BRD) is the most important and costly health issue of the feedlot industry worldwide. Remote monitoring of reticulorumen temperature has been suggested as a potential tool to improve the diagnostic accuracy of BRD. The present study aimed to evaluate 1) the difference and degree of reticulorumen hyperthermia episodes between healthy and subclinical BRD feedlot steers, 2) determine the correlation between reticulorumen hyperthermia and lung pathology, performance, and carcass traits. Mixed-breed feedlot steers (n= 148) with a mean arrival weight of 321 ± 3.34 kg were administered a reticulorumen bolus at feedlot entry and monitored for visual and audible signs of BRD until slaughter when lungs were examined and scored for lesions indicative of BRD. Post-slaughter animals with no record of BRD treatment were assigned to one of three case definitions. Healthy steers had no visual or audible signs of BRD (i.e., CIS=1), and total lung consolidation score &lt; 5% or pleurisy score &lt; 3 at slaughter. Subclinical BRD cases had a CIS of 1, and a lung consolidation score ≥ 5% or a pleurisy score of 3 at slaughter. Mild CIS cases had at least one CIS of 2, and a lung consolidation score &lt; 5% and a pleurisy score &lt; 3 at slaughter. Subclinical BRD and mild CIS cases had longer total duration of reticulorumen hyperthermia, more episodes and longer average episode duration above 40.0°C compared to healthy steers (P &lt; 0.05). A moderate positive correlation was found between lung consolidation and total duration (r = 0.27, P &lt; 0.001), episode duration (r = 0.29, P &lt; 0.001) and number of episodes (r = 0.20, P &lt; 0.05). Pleurisy score was also found to be moderately and positively correlated with total duration (r = 0.23, P &lt; 0.01), episode duration (r = 0.37, P &lt; 0.001) and number of episodes (r = 0.26, P &lt; 0.01). Moderate negative correlations were found between reticulorumen hyperthermia and carcass traits including hot standard carcass weight (HSCW) (- 0.22 ≤ r ≤ - 0.23, P &lt; 0.05) and P8-fat depth (- 0.18 ≤ r ≤ - 0.32, P &lt; 0.05). Subclinical BRD reduced carcass weight by 22 kg and average daily gain (ADG) by 0.44 kg/day compared to healthy steers (P &lt; 0.05), but mild CIS cases had no effect on performance (P &gt; 0.05). The reticulorumen bolus technology appears promising for detection of subclinical BRD cases in feedlot cattle as defined by lung pathology at slaughter.

274 Comparison of Two Ultrasound Systems for Estimation of Carcass Attributes in Feedlot Steers

Sixty-eight (68) crossbred steers were evaluated using two real-time, B-mode ultrasound units to estimate final carcass attributes. The cattle were ultrasounded at the West Texas A&M research feedlot (Canyon, Texas) and carcass data was collected at the West Texas A&M Meats Laboratory (Canyon, Texas) or Tyson Fresh Meats (Amarillo, Texas). Objectives of the study were 1) to compare ultrasound live animal data to carcass attributes at harvest 2) to evaluate the performance differences between the ALOKA 500 (ALK) and the EVO ultrasound units All ultrasound images were captured by the same Ultrasound Guidelines Council (UGC) certified technician with images being processed at the UltraInsights Laboratory (Pierce, Colorado). The correlations between 12th rib fat thickness of the carcass (FTC) and ultrasound (FTU) were 0.84 for the ALK and 0.85 for the EVO, with no differences being found between the two units (P = 0.15). Correlations between the 12-13th rib carcass ribeye area (REAC) and ultrasound ribeye area (REAU) were 0.69 for the ALK and 0.66 for the EVO. There was no difference in REAU size between the two units. Carcass marbling score (MS) and ultrasound intramuscular fat (IMFU) correlations were 0.78 for the ALK and 0.84 for the EVO. The IMF data were found to be different between the two units, with the EVO measuring a mean IMFU value of 6.03 and the ALK a value of 5.26 with the change of 0.77 being different (P &lt; 0.01). It is concluded that both ultrasound units performed favorably when predicting FTC and marbling score but were not highly correlated for REAU. It was found that the predictions between the two units on FT and REA were the same, though the EVO was higher on both. The IMFU values between the ALK and EVO were different, with the EVO again predicting higher values.

PSIII-8 Sire breed differences for carcass attributes in feedlot steers using ultrasound technology

Live animal ultrasound measurements were taken on thirty-two feedlot steers and heifers for estimation of carcass endpoints including 12th rib fat thickness (FTU), ribeye area (REAU) and intramuscular fat (%FatU). Ultrasound measurements were collected by an inexperienced technician using an Aloka 500 ultrasound unit using Beef Image Analysis (BIA) software. The objective of the study was to evaluate carcass differences of four sire breed types including Angus (n = 11), Ultrablack (n = 6), Nelore (n = 6), Braunvieh (n = 1) and Angus X Nelore X Braunvieh hybrid (n = 8). Carcass data collected at harvest included 12th rib fat Thickness (FTC), Ribeye area (REAC), marbling score (MS), Yield Grade (YG), and Quality Grade (QG). The data were analyzed using SAS to determine breed effects. Means for FTU, FTC, REAU, REAC, %FatU and MS were 0.59 cm, 0.57 cm, 90.80 cm2, 83.53 cm2, 4.83%, and 483.75, respectively. There was no significant difference (P &gt; 0.05) in YG and FT due to breed of sire. However, there was a trend for sire breed for ribeye area (P = 0.0728) for Angus X Nelore X Braunvieh cross and MS (P = 0.0786) for Ultrablack. Pearson correlation values between FTU and FTC, REAU and REAC, and %FatU and MS were 0.1217 (P = 0.05068), 0.3545 (P = .0465) and 0.5161 (P = 0.0025), respectively. These data suggest little differences existed in carcass attributes between various sire breeds out of a set of crossbred commercial cows.

151 Intake, Growth, and Insectifugal Outcomes Associated with Free-choice Supplementation of Garlic Products to Feedlot Steers

Conflicting anecdotal accounts from producers about their cattle performance and fly-repellence outcomes while receiving garlic-infused supplements have limited feeding decisions. This study evaluated differences in animal performance and insectifugal outcomes among four groups (26 steers per group) over two years (total = 208 steers). The steers either received non-garlic mineral supplement (MS), MS+0.3% garlic oil-based premix (GOil), MS+2.5% garlic powder (LGP), or MS+5% garlic powder (HGP). A completely randomized design was implemented where each steer was assigned to each treatment group while balancing for bodyweight and breed composition. Steers received a feedlot ration and free-choice mineral supplement for 86 and 108 d in the first and second year, respectively. Individual feed and supplement consumption were measured with automatic feeding units. Fly abundance on each animal was determined using digital images collected during weekly fly surveys. The ADG, feed efficiency, ultrasound body composition, and intake-related activities were also evaluated during the study. Data were analyzed using linear- or generalized linear mixed models in SAS. A significant year and Group×year interactions were observed for daily supplement intake (P &lt; 0.02). Similar interactions (P &lt; 0.04) were observed for feeding behaviors associated with supplement intake. Fly abundance during the peak months was below the economic threshold and was not different among the groups (P = 0.25), but the year and Group×year interactions were significant (P &lt; 0.02). There were no differences among the groups for DMI (P = 0.81), ADG (P = 0.54) and gain to feed ratio (P = 0.34). The Group×year interactions were present for the change in ultrasound rib-fat-thickness. The reasons behind the differences in supplement intake are not clear but may be related to the garlic products’ phytochemical profiles. These results suggest that further studies are required to identify the specific bioactive compounds in garlic that affect supplement intake.

PSII-5 Effect of progressive limit feeding in feedlot steers: A pilot study

The objective was to analyze the effect of progressive limit feeding on growth and performance during the finishing phase in feedlot steers. Thirty-nine steers (BW = 469 ± 31 kg) were divided into three blocks by weight. In each block, five steers were randomly assigned to a pen to be progressively limit fed (PLF), while the remaining eight steers were fed a common finishing diet ad libitum in a control (CON) pen. Progressive limit feeding refers to maintaining a previously growing animal at constant size by reducing the amount of feed offered by 3.29% daily for 14 consecutive days. Thus, on d 14, PLF steers were consuming 63% of original dry matter intake (DMI). All steers were fed ad libitum from d 15 until slaughter (d 106). Steers were fed a finishing diet, consisting primarily of dry-rolled corn, corn silage, and modified wet distillers grains. Data were analyzed using the MIXED procedure of SAS 9.4. Final BW was not affected (P = 0.82) by treatment; PLF and CON steers were 665 and 669 kg, respectively. Treatment did not affect overall ADG (P = 0.73); however, treatment did affect (P = 0.01) d 15–83 ADG as PLF steers gained 2.28 kg/d compared with 1.90 kg/d for CON steers. Overall DMI of PLF steers was 9% less (P = 0.02) than for CON steers (9.9 and 10.9 kg/d, respectively). Treatment did not affect (P = 0.10) DMI from d 15–106. Overall gain:feed (0.183 and 0.173 for PLF and CON steers, respectively) was not affected (P = 0.46) by treatment. Carcass characteristics were not affected (P ≥ 0.24) by treatment. A similar overall growth performance and reduced DMI for PLF steers suggests that progressive limit feeding may be a cost-effective approach to finishing feedlot steers.

PSIV-15 Examining the relationship between breed type and anabolic implant protocols in performance in the feedlot, health, and temperament of beef steers

The purpose of this research was to compare anabolic implant protocols in feedlot steers of two different breed types. Sixty steers were stratified by weight and breed in a 2 x 3 factorial design examining two different breeds: Angus (AN; n = 38) or Santa Gertrudis influenced (SG; n = 22), and three implant strategies: no implant (CON; n = 20), a moderate implant protocol (d0 implant: Revalor-G, d56 implant: Revalor-IS, d112 implant: Revalor-S; MOD; n = 20), or a vigorous implant protocol (d0 implant: Revalor-IS, d56 implant: Revalor-S, d112 implant: Revalor-200; VIG; n = 20). Steers were randomly placed into pens equipped with GrowSafe® bunks and fed the same ration. Weight, chute score (CS), exit velocity, blood, temperature, hip height and 12th rib fat thickness were collected approximately every 28d over a 112d period. Over the 112 d, SG steers tended (P = 0.10) to gain more hip height than AN steers. Anabolic implant protocol influenced total gain with both VIG and MOD steers gaining more (P &lt; 0.01) than CON. On d 0, SG steers had a higher (P &lt; 0.01) CS compared to AN steers, with this being maintained through the course of the trial. There was also as a tendency for there to be a breed*treatment effect (P = 0.06) on d112, with SG-MOD having a higher (P = 0.04) CS than AN-VIG, and a tendency (P = 0.08) for SG-VIG to have a higher CS than AN-VIG. Moderate and VIG implant protocols may be a useful tool to increase performance in feedlot steers. However, this research did find that SG influenced steers may have a more excitable temperament, but implant protocol did not influence (P &gt; 0.05) temperament.

Diurnal Ruminal pH and Temperature Patterns of Steers Fed Corn or Barley-Based Finishing Diets

This study evaluated the effects of corn or barley finishing diets on ruminal pH and temperature and their relationship to feed intake events using continuous reticulorumen monitoring of feedlot steers. Average daily ruminal pH and temperature were not impacted (p ≥ 0.17) by diet. However, diet did affect daily variation of ruminal pH and temperature (p < 0.01). Average hourly ruminal pH displayed a diet by hour post-feeding interaction (p < 0.01), where barley-fed steers had greater (p < 0.01) ruminal pH than corn-fed steers at 0, 1, 18, 19, 20, 21, 22 and 23 h post feeding, but had lower (p ≤ 0.05) ruminal pH than corn-fed steers at 6, 7, and 8 h post-feeding. Variation in ruminal pH hour post-feeding also displayed a diet by hour post-feeding interaction (p < 0.01), where barley-fed steers had greater (p ≤ 0.03) variation in ruminal pH at hours 1–17 post-feeding but did not differ (p ≥ 0.16) at 0, 18, 19, 20, 21, 22 and 23 h post-feeding. Additionally, average hourly ruminal temperature exhibited a diet by hour post-feeding interaction (p < 0.01). In summary, basal grain interacted with time post-feeding influencing ruminal pH and temperature in feedlot steers.