Effects of a novel direct-fed microbial on growth performance, carcass characteristics, nutrient digestibility, and ruminal morphology of beef feedlot steers

by Selleckchem | Jan 16 2024

The effects of a novel direct-fed microbial on feedlot performance, carcass characteristics, digestibility, ruminal morphology, and volatile fatty acid (VFA) profile of finishing steers were evaluated. Single source Angus-crossbred yearling steers (n = 144; initial BW = 371 ± 19 kg) were used in a randomized complete block design. Steers were blocked by initial BW and randomly assigned to treatments (12 pens/treatment; 4 steers/pen). Treatments included: A) CONTROL (no DFM, tylosin, or monensin; B) MONTY (monensin sodium [330 mg/animal-daily] and tylosin phosphate [90 mg/animal-daily]); and C) MONPRO (monensin sodium [same as previous] and L. salivarius L28 [1 × 10⁶ CFU/animal-daily]). Treatments were included in a steam-flaked corn-based finisher diet offered once daily using a clean-bunk management for approximately 149 d. The digestibility assessment was performed from d 70 to d 74. Ruminal fluid and rumen tissue samples were collected at the slaughter for VFA profile and papillae morphology analyses, respectively. Data were analyzed using the GLIMMIX procedure of SAS with pen serving as the experimental unit, treatment as fixed effect, and BW block as random effect. Steers offered MONPRO had on average 5.3 % less (P < 0.01) dry matter intake (9.56 kg/d) compared to either CONTROL (10.16 kg/d) or MONTY (9.96 kg/d). The carcass-adjusted final BW (613 kg; P = 0.23), overall ADG (1.64 kg/d; P = 0.23), and gain-efficiency (0.165; P = 0.61) were not affected by treatments. Steers offered CONTROL had greater (P < 0.01) marbling score and tended (P = 0.06) to have less carcasses grading Select and tended (P = 0.10) to have more carcasses grading Upper-Choice, while other carcass characteristics and liver-abscesses were not affected (P ≥ 0.23) by treatments. The digestibility of nutrients (P ≥ 0.13) and the ruminal VFA profile (P ≥ 0.12) were not affected by treatments. Steers offered MONPRO tended (P = 0.09) to have 16% greater average papillae number compared to other treatments. Yearlings offered finishing diets containing L. salivarius L28 plus monensin did not affect growth performance, digestibility, or ruminal VFA, but reduced feed intake. Carcass quality was negatively affected by treatments, while animals consuming L. salivarius L28 and monensin tended to improve ruminal morphology. Current findings in ruminal morphology and feed intake may warrant further assessment of diets containing L. salivarius L28 on beef cattle food safety aspects.

Comments:

This study seems quite comprehensive in its evaluation of the effects of the novel direct-fed microbial (DFM) on various aspects of feedlot performance and animal characteristics. It appears that the inclusion of L. salivarius L28 along with monensin did not significantly impact growth performance, digestibility, or ruminal volatile fatty acid (VFA) profiles. However, there were some noteworthy findings:

1. **Feed Intake:** Steers offered MONPRO (L. salivarius L28 and monensin) had a reduced dry matter intake compared to the other treatments. This reduction could be significant for feed management strategies.

2. **Carcass Quality:** The carcass characteristics were affected, with the CONTROL group showing greater marbling scores and tendencies towards different carcass grades compared to the other treatments. This indicates a potential impact of the microbial inclusion on meat quality attributes.

3. **Ruminal Morphology:** There was a tendency for steers offered MONPRO to exhibit an increase in average papillae number, which could imply a positive effect on ruminal morphology, possibly linked to improved nutrient utilization.

4. **No Significant Impact on Digestibility or VFA Profiles:** Despite the differences in feed intake and ruminal morphology, there were no significant effects observed in nutrient digestibility or ruminal VFA profiles among the treatments.

The conclusion that the addition of L. salivarius L28 and monensin did not substantially affect growth performance or ruminal fermentation but influenced feed intake and carcass quality is a critical observation. It highlights the potential for further investigation, especially in understanding the mechanisms behind the observed changes in feed intake and carcass traits.

The mention of potential further assessment regarding food safety aspects is interesting and underscores the need for a comprehensive evaluation beyond growth and carcass parameters.

If you're delving deeper into this area, exploring the mechanisms behind the observed effects on feed intake and carcass quality could provide valuable insights. Additionally, considering the implications for food safety in beef cattle production could be a crucial direction for future research or practical applications.