Effect of an Accelerated Adaptation Protocol on Performance and Health of Feedlot Steers Drenched with Lactipro

Authors: Rebecca L. McDermott, Graduate Student and Research Technician; Samuel E. Loy, Undergraduate Student; Isaque F. Vicci, Research Technician, Animal Science, Lincoln; Mark Corrigan, Braden C. Troyer, Axiota Animal Health, Fort Collins, CO; Galen E. Erickson, Professor, Jim C. MacDonald, Professor, Animal Science, Lincoln.

Summary with Implications

A finishing study evaluated the effects of an accelerated adaptation protocol in conjunction with Lactipro on performance and health of steers. Five adaptation programs were evaluated with steers adapted to a finishing diet in 21, 14, 7, or 0 days. An additional accelerated adaptation program provided intensive feed delivery with 0-d adaptation. Cattle assigned to the 21-d and 0-d adaptations gained faster and consequently had greater HCW compared to the 7-d and 14-d adaptation, resulting in a quadratic response for ADG and HCW. The 0-d adaptation with intensive feed delivery had similar ADG and HCW compared to the 21-d and 0-d adaptation suggesting more frequent feed delivery during the initial days of adaptation does not prove to be beneficial. No differences were observed for any health outcomes. These data suggest that when cattle are drenched with Lactipro NXT, an accelerated adaptation approach with 100% finisher is suitable as it yields similar results to a traditional 21-d adaptation program.

Introduction

Forage-based, lower energy adaptation rations are used to transition cattle over a period of 3-4 weeks to high-grain diets consisting of readily fermentable carbohydrates. This slowly adapts the ruminal ecosystem and more importantly the animal’s eating behavior. The adaptation period is especially important to ensure lactate utilizing bacteria can multiply to prevent lactic acid accumulation. However, the adaptation period comes with its own challenges for feedlots such as roughage acquisition, handling, shrink, feeding, and the need for multiple diets to be milled and delivered at the feedlot. Implementation of accelerated step-up protocols could improve the feedlot’s operational efficiency and animal performance. Megasphaera elsdenii is a ruminal bacteria responsible for utilizing lactate produced in the rumen when cattle are adapted to a high-starch diet. Naturally occurring M. elsdenii can take weeks for the rumen to reach a healthy population to effectively handle high-starch diets. Lactipro delivers an immediate, viable population of M. elsdenii directly to the rumen, thus reducing the time needed for the rumen ecosytem to adapt. The objective of this study was to evaluate the effects of utilizing an accelerated adaptation program on performance and health of steers entering the feedlot but instead of dosed with Lactipro.

Procedure

A finishing study was conducted at the Eastern Nebraska Research, Extension, and Education Center using 1,000 crossbred steers (initial BW = 888 lb; SD = 66) in a generalized randomized block design. To mimic cattle coming off grass pasture, steers were fed a ration consisting of 67% grass hay and 33% ryelage with ad libitum access, beginning four days prior to the first day weight for each block on d 0. The individual unshrunk weights captured on d 0 were used to assign cattle to pen. After processing d 0, cattle were placed into pens with 18 inches of bunk space per head and fed starter ration at approximately 1.9% of BW (DM basis). Cattle were weighed again on d 1. The two consecutive day weights were used to establish initial BW. Steers in each starting block were blocked by BW into light, medium, and heavy BW blocks [n = 2, 6, and 2 replicates, respectively] based on first day unshrunk BW, stratified by BW within block, and assigned randomly to pen within block. Pens within block were assigned randomly to 1 of 5 treatments, with a total of 20 steers per pen and 10 replications per treatment.  

Treatments were designed to evaluate the length of an accelerated adaptation phase (0, 7, or 14-d) compared to a traditional adaptation (21-d). Dietary treatments included 1) traditional 21-d adaptation (TRAD-21; 100% finisher on d 21), 2) accelerated 14-d adaptation (ACC-14; 100% finisher on d 14), 3) accelerated 7-d adaptation (ACC-7; 100% finisher on d 7), 4) accelerated 0-d adaptation (ACC-0; 100% finisher on d 2), and 5) accelerated 0-d adaptation with intensive feed delivery (ACC-0+, 100% finisher on d 2). All cattle were fed 3 times daily for the first 30 days, except cattle on the ACC-0+ treatment, which were fed 6 times daily for d 2-5 and transitioned to 3 times daily from d 6. Cattle were fed twice daily for the remainder of the trial.

A two ration-blending system was used for the adaptation period. The starter and finisher rations are provided in Table 1. The finishing ration was changed from 7% corn silage and 4% corn stalks to 15% corn silage on d 78 due to forage availability. Steam flaked corn was processed to a flake density of 27.8 lb/bu. All steers were offered the starter diet on d 1 at approximately 1.9% of BW (DM basis) after processing. Beginning on d 2, cattle started their respective adaptation protocol. Bunk space was limited to 9 inches per head based on current recommendations from consulting nutritionists in Nebraska.

Beginning on d 2, dry matter cuts and bumps for all treatments were based on a % of maintenance energy intake determined by cattle aggression and bunk scores. This approach was used to maintain continuity in energy increases between replicates and different treatments. Prior to the first feeding, bunk scores (1-5) were recorded for each pen. For the first feeding, 30% of the previous day’s intake was fed. During the first round of feeding, trained personnel followed the feed truck and recorded cattle aggression scores (1-4) based on % of cattle at the bunk, with 1 being most aggressive and 4 being the least aggressive. The average of the bunk score prior to the first feeding and cattle aggression score at the first feeding were used to determine a bunk call for the day (1 to 4.5). The bunk call was then associated with a decrease, no change, or increase in energy intake (NEg; Mcal/d). Energy intake was associated with dry matter delivery for the remaining feed deliveries each day. 

On d 1, all steers were implanted with a Revalor-XS and given an oral dose of 20 mL of Lactipro NXT (1.0 x 1010 CFU; Axiota Animal Health; Fort Collins, CO). After an average of 152 d on feed, cattle were harvested at a commercial abattoir, where hot carcass weight (HCW) and liver abscesses were recorded. After a 48-hr chill, carcass characteristics including marbling score, longissimus muscle (LM) area, and yield grade were recorded. Dietary NEm and NEg values were calculated based on intake, ADG, and BW of cattle, using NRC (1996) equations.

Data were analyzed using the MIXED procedure of SAS (SAS Institute Inc., Cary, N.C.) with pen as the experimental unit, block as a fixed effect, and weight block nested within start block. Orthogonal contrasts defined linear and quadratic effects of TRAD-21, ACC-14, ACC-7 and ACC-0, the effect of ACC-0 vs. ACC-0+, and the effect of TRAD-21 vs. ACC-0+. Probabilities less than or equal to alpha (P ≤ 0.05) were considered significant, with tendencies acknowledged at P > 0.05 and P ≤ 0.10.

Results

Finishing performance and carcass characteristics are summarized in Table 2 and health outcomes are summarized in Table 3. Dry matter intake responded quadratically (P = 0.01) with the greatest DMI observed at TRAD-21 and the least DMI at ACC-7. Cattle assigned to TRAD-21 and ACC-0 treatments gained faster compared to those in ACC-14 and ACC-7 treatments, which were similar, resulting in a quadratic response for ADG (P = 0.01). The lower ADG observed for the ACC-14 and ACC-7 treatments could be associated with a lack of starch in the rumen early in the adaptation phase limiting substrate availability for the dosed M. elsdenii to multiply and establish a healthy population. This challenge wasn’t observed with the TRAD-21 treatment because cattle were gradually transitioned to a higher starch diet. As a result, the native microbial population, including M. elsdenii, had time to adapt naturally without needing large starch input early on. Accordingly, cattle assigned to TRAD-21 and ACC-0 treatments had greater HCW and final BW compared to those in ACC-14 and ACC-7 treatments. The ACC-0+ treatment had similar ADG, HCW, and final BW to the TRAD-21 and ACC-0 treatments (P ≥ 0.58) suggesting more frequent feed delivery during the initial days of the adaptation phase did not prove to be beneficial. Feed conversion tended to respond quadratically (P = 0.07) with an increase in F:G for cattle on ACC-14. Longissimus muscle area also tended to respond quadratically in a similar manner to HCW (P = 0.06). Liver abscesses decreased linearly with cattle assigned to TRAD-21 treatment having a greater prevalence of liver abscesses and cattle assigned to ACC-0 having the lowest (P = 0.02). No differences were observed for liver abscesses for the ACC-0+ treatment compared to the TRAD-21 or the ACC-0+ compared to the ACC-0 treatment (P ≥ 0.20). No other differences (P ≥ 0.16) were observed for carcass characteristics or health outcomes. 

Conclusions

These data suggest that when cattle are drenched with Lactipro NXT, an accelerated adaptation approach with 100% finisher from the beginning is suitable because cattle performance is similar to a traditional adaptation program. This is likely because feeding 100% finisher displaces forage with starch therefore increasing substrate availability that the microbes provided in Lactipro can utilize. Additionally, this approach improves feedlot’s operational efficiency by improving mill efficiency with the need for less diets and reducing forage usage by 22%. 

Acknowledgment

Funding for this research was provided by Axiota Animal Health. Products used in this study were provided by Elanco Animal Health, Merck Animal Health, and Zoetis Inc.

Copyright © 2025 The Board of Regents of the University of Nebraska. All rights reserved.