Vaccination Timing Does Not Affect Growth Performance but Enhances Antibody Titers in Previously Vaccinated Calves

Simple Summary

Limited information is available regarding the timing of vaccine administration to low-risk, relatively unstressed beef calves upon arrival to a feedlot facility. The objective of this study was to evaluate health measures, growth performance, and antibody titer responses in previously vaccinated newly weaned calves that were administered vaccinations upon arrival to a feedlot facility compared to calves not receiving vaccination upon arrival. Growth performance and health measures were not dependent upon the timing of vaccination following arrival to a feedlot facility; however, calves vaccinated upon arrival did report higher antibody titer concentrations compared to calves that did not receive vaccination. Collectively, providing additional vaccination upon arrival to low-risk, relatively unstressed calves did not appreciably improve feedlot performance but may provide additional antibody titers if calves were to experience immunological challenges in the feedlot.

Abstract

The objective of this study was to evaluate the health, growth performance, and antibody titers of previously vaccinated newly weaned calves administered a respiratory and clostridial vaccine compared to no vaccination upon arrival. Single-sourced, newly weaned beef steers [n = 70; initial body weight (BW) = 254 ± 5.9 kg] were allotted to 10 pens (n = 5 pens/treatment; 7 steers/pen). Steers were blocked by BW in a randomized complete block design and assigned to one of two treatments: VAC (vaccinated for respiratory and clostridial species upon arrival) or NOVAC (not vaccinated upon arrival). Steers were individually weighed on d 0 (arrival), 1, 21, and 42 for growth performance measures. Whole blood samples were collected (n = 3 steers/pen) on d 1, 21, and 42 via jugular venipuncture for antibody titer responses. Depression scores (DS) of 0 (normal) to 4 (moribund) were recorded daily for each individual steer for 21 d. Dry matter intake as a percentage of BW tended (p = 0.07) to increase for the NOVAC group compared to the VAC group. No treatment × day interactions (p ≥ 0.50) were observed for DS or antibody titers. Growth performance was unaffected by vaccination but vaccinated calves had greater antibody titer responses throughout the 42 d study.

1. Introduction

Bovine respiratory disease (BRD) is the most costly disease and the leading cause of morbidity and mortality in United States feedlots [1]. This is caused in part by the segmented characteristic of the beef industry resulting in the transport of cattle between different feeding facilities, making prevention of disease more challenging [2]. Even though vaccination against viral and bacterial pathogens that lead to BRD has been proven to be an effective means to control disease, there is a body of evidence suggesting that respiratory vaccinations are not as effective in immunocompromised peri-weaned calves [2,3,4].

Newly weaned calves commonly go through a variety of stressors, such as transportation as well as feed and water deprivation, during the initial 24 h post-weaning period [5]. The severity of these stressors (time off feed/water, transit time, weather, etc.) can influence the calf’s immune system. It has been reported that a large portion of calves (62.5%) that come through an auction facility have already received at least one vaccination prior to weaning [6]. Incorporating vaccination protocols during preconditioning phases has been shown to build immunity in cattle prior to anticipated exposure to stressors and pathogens [7,8], such as the weaning event. However, there is limited information regarding the performance of calves once they are in a backgrounding facility that have already received vaccinations prior to the weaning event.

Calves respond differently to the stressors applied at the time of weaning based on their vaccination status [2]. Thus, knowing prior vaccine and management history is important to consider when receiving cattle into a feedyard to determine the effective timing of vaccination. Further investigation is needed to determine the proper vaccination timing protocols for calves that have received a prior vaccination and are directly shipped from the ranch to the receiving feedyard without passing through marketing facilities. Therefore, we hypothesized that previously vaccinated, newly weaned calves administered vaccinations upon arrival would have increased antibody titers, improved health, and enhanced growth performance measures compared to calves not receiving vaccination upon arrival. To test this, the objective of this research was to evaluate health measures, growth performance, and antibody titers to Infectious Bovine Rhinotracheitis (IBR), Bovine Virus Diarrhea (BVD) Type I and II, Parainfluenza (PI₃), and Bovine Respiratory Syncytial Virus (BRSV) in previously vaccinated, newly weaned calves—either administered a respiratory and clostridial vaccine on arrival or with no administration of vaccinations upon arrival.

2. Materials and Methods

2.1. Institutional Animal Care and Use Approval

This study was conducted at the Ruminant Nutrition Center in Brookings, SD, between October and December 2021. The animal care and handling procedures used in this study were approved by the South Dakota State University Animal Care and Use Committee (2109-061E).

2.2. Cattle Management and Treatments

Single-sourced Charolais × Angus crossbred steers (n = 70; initial BW = 254 ± 5.9 kg) were used in a 42 d receiving phase study. Steers were procured from the same ranch in western South Dakota where all steers were managed similarly in a rangeland setting from birth to weaning. Approximately 30 d prior to the weaning event, all steers were vaccinated against IBR, BVD Types I and II, PI₃, and BRSV (Pyramid 5 Plus Presponse, Boehringer Ingelheim Animal Health, Duluth, GA, USA); Clostridium chauvoei, C. septicum, C. novyi, C. sordelli, C. perfringens Types C and D, and Haemophilus somnus (Vision 7 Somnus with Spur, Merck Animal Health, Rahway, NJ, USA); and treated against internal (Ivermectin Injection, Durvet Inc., Blue Springs, MO, USA) and external parasites (Standgaurd, Elanco Animal Health, Greenfield, IN, USA). On the day of weaning (d − 1), all steers were transported approximately 513 km to the Ruminant Nutrition Center in Brookings, SD. Steers were provided with long-stem grass hay in bunks the day of receiving. On d 0, steers were individually weighed (scale readability 0.454 kg) to determine an allotment BW. On d 1, steers were again weighed and assigned to 1 of 10 pens (n = 5 pens/treatment with 7 steers/pen) in a randomized complete block design (blocked by initial BW) into two treatments: vaccinated for IBR, BVD I and II, PI₃, and BRSV (Bovi-Shield Gold 5, Zoetis, Parsippany, NJ, USA), and clostridial species (Ultrabac 7/Somubac, Zoetis) upon arrival [VAC] or not vaccinated [NOVAC]. Steers assigned to the VAC treatment group were administered vaccinations on d 1. All steers were fed in small pipe and cable pens (7.62 m × 7.62 m concrete surface pens with 7.62 m of concrete bunk space) with automatic heated waters.

2.3. Dietary Management

Fresh feed was manufactured and fed twice daily in a stationary mixer (2.35 m³; scale readability 0.454 kg). The diet [

Table 1. Diet formulation for a 42 d study for previously vaccinated, newly weaned steers vaccinated for Infectious Bovine Rhinotracheitis, Bovine Virus Diarrhea Type I and II, Parainfluenza-3, Bovine Respiratory Syncytial Virus, and clostridial species upon arrival (VAC) or not vaccinated upon arrival (NOVAC).

Item	d 1 to 42
Wheatlage, %	39.43
Liquid Supplement 1, %	5.16
Oat Hay, %	10.10
Dried Distillers Grains Solubles, %	9.39
Soybean Hulls, %	35.93
Diet Composition
Dry Matter, %	51.11
Crude Protein, %	12.92
Neutral Detergent Fiber, %	56.49
Acid Detergent Fiber, %	38.64
Ash, %	6.99
Ether Extract, %	2.62
Net Energy of Maintenance, Mcal/kg	1.72
Net Energy of Gain, Mcal/kg	1.04

¹ Liquid supplement (all values except dry matter on a dry matter basis): 36.27% crude protein; 28% non-protein nitrogen; 0.74 Mcal/kg of net energy for maintenance; 0.50 Mcal/kg of net energy for gain; 1.62% crude fat; 1.06% crude fiber; 4.62% calcium; 0.43% P; 2.28% K; 0.47% Mg; 5% NaCl; 3.38% Na; 0.54% S; 4 ppm Co; 200 ppm Cu; 20 ppm I; 25.15 mg/kg of ethylenediamine dihydroiodide; 150.29 ppm Fe; 400 ppm Mn; 3.08 ppm Se; 700 ppm Zn; 44,092 IU/kg of vitamin A; 440.92 IU/kg of vitamin E; and 551 g/Mg of monensin sodium (Rumensin, Elanco, Indianapolis, IN, USA).

; dry matter (DM) basis] consisted of ingredients common to the northern plains feeding region and was provided at an ad libitum amount. Liquid supplement was included to provide monensin sodium (Rumensin 90; Elanco, Indianapolis, IN, USA) at 27.5 g/kg (DM basis) and vitamins and trace minerals to meet nutrient requirements for growing and finishing beef cattle [9]. Diets presented in Table 1 are the actual DM diet composition, plus tabular nutrient concentrations and energy values calculated according to Preston [10].

If carryover feed was present the following morning, orts were collected, weighed, and dried in a forced air oven at 100 °C for 24 h to determine DM content. The DMI of each pen was adjusted to reflect the total DM delivered to each pen after subtracting the quantity of dry orts for each interim period. Weekly DM analysis (drying at 60 °C until no weight change), tabular nutrient values [10], and corresponding feed batching records were used to determine actual diet formulation and nutrient composition. Weekly samples were composited into monthly samples for analysis of nutrient composition. Proximate analysis of each ingredient was conducted monthly according to the following: DM [method no. 935.29 [11]]; N [method no. 968.06 [12]]; ether extract [method no. 2003.06 [13]]; neutral detergent fiber [method no. 2002.04, [14]]; acid detergent fiber [method no. 973.18, [15]]; and ash [method no. 942.05 [16]].

2.4. Depression Scores

Depression scores (DS) were recorded by a trained observer daily for each individual steer within each pen in the morning prior to feeding from d 1 to 21 to determine clinical signs of BRD [17]. Depression scores were recorded based on the proportion of steers within the pen that reported each level of DS. Depression scores were ranked on the following scale: 0 = normal, no signs of disease or depression; 1 = noticeable depression, signs of weakness are usually not apparent, slower than pen mates but still perks up when approached and does not appear weak, actively follows your movements with a raised head; 2 = marked depression, moderate signs of weakness may be apparent but without significantly altered gait, stands with head lowered, will perk up when approached but will return to depressed stance, moves slowly, falls toward back of group, and may display signs of weakness such as incoordination; 3 = severe depression accompanied by signs of weakness such as altered gait or lowered head, obviously very weak, displaying difficulty in moving with group, raised head only when approached closely; or 4 = moribund, unable to rise.

2.5. Antibody Titers

Whole blood samples were collected via jugular venipuncture from a subsample of steers (n = 3 steers/pen, closest to the pen mean BW; the same 3 steers were used throughout the study duration) on d 1, 21, and 42 using an evacuated tube (Vacutainer tube) and a 16 ga × 3.81 cm needle into two 10 mL non-additive tubes. After collection, blood samples were allowed to clot at 20 °C for 30 min before centrifugation at 1250× g at 4 °C to harvest sera. Serum was stored in quintuplicate aliquots (one aliquot per antibody) at −80 °C. Sera were individually analyzed at a commercial animal disease research and diagnostic laboratory for titer concentrations and interpretations according to the laboratory’s standard operation procedures. Individual animal sera were analyzed to determine the number of positive titers and the titer concentrations. Positive titers were indicated by having a dilution factor equal to or greater than 1:8 parts as determined by the diagnostic laboratory. This is referred to as the proportion of steers with positive titers to each antibody. Individual animal data was then averaged within each pen for statistical analysis.

2.6. Growth Performance Calculations

Steers were individually weighed on d 0, 1, 21, and 42. Cumulative daily weight gain was based on initial BW (average of full BW of d 0 and 1 with no shrink applied) and final shrunk BW (a 4% pencil shrink was applied to d 42 BW). Average daily gain (ADG) was calculated as the difference between final shrunk BW and initial BW, divided by the days on feed for the respective period. Feed efficiency, or the gain-to-feed ratio (G:F) was calculated by dividing the ADG by dry matter intake (DMI). Dry matter intake as a percentage of BW was calculated from the average BW divided by the average DMI for that period.

2.7. Dietary NE Utilization Calculations

Observed dietary net energy (NE) was calculated from the daily energy gain (EG; Mcal/d) according to the medium frame steer calf equation using mean equivalent BW [median feeding BW × (478/534)]: EG, Mcal/d = ADG^1.097 × 0.0557 W^0.75; energy gain was the daily deposited energy and W was the mean equivalent BW [9]. Maintenance energy required (EM; Mcal/d) was calculated by the following equation: EM, Mcal/d = 0.077 BW^0.75 [9,18] where BW is the average of initial shrunk BW and final shrunk BW (initial BW shrunk 4% and final BW shrunk 2%). Using the estimates required for maintenance and gain, the observed dietary NE_m and NE_g values of the diet were generated using the quadratic formula: $x={\displaystyle \frac{-b\pm \sqrt{b^2-4ac}}{2c}}$, where x = NE_m, Mcal/kg, a = −0.41 EM, b = 0.877 EM + 0.41 DMI + EG, c = −0.877 DMI, and NE_g was determined from the following formula: 0.877 NE_m – 0.41 [19,20]. The observed-to-expected NE ratio was determined from observed dietary NE for maintenance or gain divided by tabular NE for maintenance or gain. To calculate predictive values, a final body weight of 665 kg was assumed to be the mature body weight from previous data on steers of similar composition [21].

2.8. Statistical Analysis

Data were analyzed using analysis of variance appropriate for a randomized complete block design experiment using the GLIMMIX procedures of SAS 9.4 (SAS Inst. Inc., Cary, NC, USA). A power test was conducted based on previous research at the facility that indicated that 5 replicate pens per treatment were adequate to detect performance differences of 10%. Vaccination status was included as a fixed effect, and block was considered a random factor; pen served as the experimental unit for all analyses. The MIXED procedure in SAS 9.4 was used to analyze DS and antibody titers. Day was included as a repeated measure, with initial proportions (DS and positive titers) or concentrations (titers) included as covariates. Individual animal proportions and concentrations were averaged within each pen for statistical analyses. Compound symmetry was included as the covariate structure. Each animal was included as a subject for repeated analyses. A log transformation was used to convert antibody titer concentrations for statistical analysis. Least squares means (LSMEANS) were generated and treatment effects were separated using the least significance differences (PDIFF with LINES option). An α level of 0.05 determined significance and an α level of 0.06 to 0.10 was considered a tendency.

3. Results and Discussion

Calves sold through auction facilities have been shown to be more profitable for producers if calves receive previous vaccination [22]. Auction facilities have implemented programs for calves previously vaccinated that have added value to calves [23] and resulted in improved health and/or performance following the weaning event. Maguire [8] stated that calves vaccinated ≥30 d prior to weaning and revaccinated ≥14 d following the backgrounding facility arrival resulted in a 17.5% reduction in mortality. As a result, these calves have been termed as low risk. In a survey of calves sold through an auction facility, 62.5% of calves had received at least one vaccination prior to coming through the sale barn [6]. The same survey also stated that calves administered vaccination prior to weaning received, at minimum, a premium of USD 1.97 per hundred weight over unvaccinated calves at auction [6]. However, there is limited information regarding the health and growth performance of cattle that are previously vaccinated and the timing of additional vaccination once they are received into a backgrounding facility.

In the present study, calves were either vaccinated upon arrival or did not receive a vaccination for the 42 d study. It has been suggested that delaying vaccination of high-risk calves until 14 to 30 days after feedlot arrival improves health and performance [24,25]. Previous research has indicated that having appropriate preconditioning strategies (vaccinating calves ≥ 30 d prior to weaning) plays a key role in decreasing morbidity rates associated with BRD [7] and may influence the timing of subsequent vaccination. It was also noted that proper vaccination protocols should be recommended based on what is ideal for the producer, location, specific phase of production, and management practices [26]. The calves in the present study were not immunologically naïve because they were previously vaccinated before weaning and were relatively unstressed as they were transported directly to the receiving facility compared to calves transitioned through an auction facility. Therefore, to better understand the timing of vaccination in the backgrounding facility with this type of calves, vaccination was delayed the entire 42 d receiving period, which would represent a common receiving period for recently weaned calves before they are transitioned to a finishing yard.

3.1. Depression Scores

No steers in the present study had DS higher than a score of 1 (Figure 1) and no steers were treated throughout the study. The low observed DS are likely because of pre-weaning vaccination status or management factors prior to or upon arrival to the receiving facility as both treatments did not report DS higher than a score of 1. There were no treatment × day interactions (p > 0.05) for DS during the 21 d evaluation period. However, there was a day effect (p < 0.01) where steers from both treatments had a greater proportion of DS of 1 on d 7 compared to the rest of the first 21 d. This is similar to a study by Step et al. [7], where the highest morbidity rates were observed at an average of 7.62 d and 7.21 d for single vaccinated and revaccinated calves, respectively, from newly weaned calves that received vaccination upon arrival with or without revaccination 11 d later. This presents a potential timeframe of observation of BRD symptoms in newly received cattle. This also emphasized that calves receiving vaccination prior to feedlot arrival have reduced mortality [8]. As the calves in the present study were transported directly from the ranch to the receiving yard without traveling through an auction facility, and were not commingled with calves from outside sources, it is likely that these calves experienced less stress compared to the general population of calves entering grow yards [27,28,29]. This could further explain the lack of differences in DS as well as the lack of heightened DS (>1) observed. Calves reported to have DS greater than 1 are considered high-risk calves and typically have traveled through auction facilities and been commingled with calves from different sources [7]. Another factor to consider is that all calves in the present study were consuming long stem grass hay out of the concrete bunks on d 0 and were offered a receiving ration on d 1. This is important to note as the consumption of feed allows rumen microbes to remain active and avoid risk of acidosis [9], which may aid in the maintenance of health and prevention of heightened depression scores.

3.2. Antibody Titers

There were no treatment × day interactions (p > 0.05) for the proportions of positive titers or antibody titer concentrations for the antibodies analyzed. There were also no day effects (p > 0.05) for IBR, BRSV, and BVD Type I or II.

There was a treatment effect (p < 0.05) for the proportion of steers with positive titers (Figure 2) and for log titer concentrations for IBR (Figure 3). Steers in the VAC treatment had a greater (p = 0.04) proportion of steers with positive IBR titers compared to NOVAC steers (59.42% vs. 37.25%). Limited information is available that specifically discusses IBR titer responses in calves that were previously vaccinated and revaccinated. However, in a study where calves vaccinated approximately 30 d prior to weaning and at weaning were compared to calves that did not receive any vaccinations, they reported a greater proportion of steers with positive titers (25% vs. 1%) compared to the calves that were not vaccinated [30]. It is important to note that the proportion of NOVAC steers with positive titers remained constant (37.25%) throughout this study, which is higher than the levels observed in vaccinated calves by Kirkpatrick et al. [30]. Steers in the VAC treatment had increased (p = 0.03) IBR titer concentrations compared to NOVAC steer concentrations (1.14 vs. 0.95). Kirkpatrick et al. [30] reported increased IBR titer concentrations in calves vaccinated approximately 30 d prior to weaning and at weaning compared to calves that did not receive any vaccinations. This is similar to Menanteau-Horta et al. [31], where calves vaccinated at 84 (36 d prior to weaning) and 196 d (76 d after weaning) of age had increased IBR titer concentrations compared to calves only vaccinated at 196 d of age. Thus, it appears that vaccination prior to weaning increased IBR titer concentrations regardless of the timing of revaccination. This provides beneficial information about the long-term immunity of calves. Providing additional vaccination upon receiving facility arrival can increase the proportion of positive titers and titer concentrations compared to no vaccination, which is advantageous for enhancing calf immunity.

There was a treatment effect (p < 0.05) for the proportion of steers with positive titers (Figure 4) and log titer concentrations (Figure 5) for PI₃. All VAC steers had positive (p = 0.04) PI₃ titers throughout this study compared to only 80% of NOVAC steers with positive titers. Kirkpatrick et al. [30] only observed 50% of calves with positive titers for PI₃ when calves were vaccinated 30 d prior to weaning and at weaning compared to 32% of control calves that were not vaccinated. Increased (p = 0.01) PI₃ antibody titer concentrations were also noted for VAC steers compared to NOVAC steers (1.93 vs. 1.18). This agrees with Kirkpatrick et al. [30], where vaccinated calves had increased titers at weaning and 42 d into the study, as well as with Schumaher et al. [32], where steers had increased PI₃ titers following additional vaccination at weaning compared to delaying vaccination 15 d after weaning. Fulton et al. [33] also observed increased overall PI₃ titer concentrations when calves were vaccinated 95 d prior to weaning and at weaning compared to calves that did not receive vaccinations. Providing additional vaccination increased the proportion of steers with positive titers and the concentration of titers for PI₃, which is noteworthy for enhancing immune responses in weaned calves. Regardless of the timing of additional vaccination, initial administration prior to weaning appears to increase antibody titers in preparation for potential challenges during the weaning event.

There was also a day effect (p < 0.05) for PI₃ titer concentrations (Figure 6) where titer concentrations were increased (p = 0.03) on d 21 compared to d 42 (1.72 vs. 1.38, respectively) but both were similar to d 1, which was intermediate (1.44). Similar titer concentration levels were reported on the day of weaning and 42 d later in the study by Kirkpatrick et al. [30] for calves that were not vaccinated; however, the calves that were vaccinated 30 d prior to weaning and at weaning reported similar titer concentrations at these timepoints but had increased concentrations 42 d following weaning, which disagrees with the present study. Still, it does appear the initial vaccine administration prior to weaning resulted in increased titer concentrations throughout the receiving period.

There was a treatment effect (p < 0.05) for the proportion of steers with positive titers (Figure 7) and log titer concentrations (Figure 8) for BRSV. Steers in the VAC treatment group had a greater (p = 0.04) proportion of steers with positive titers for BRSV compared to NOVAC steers (98.96% vs. 81.04%). This contradicts Kirkpatrick et al. [30], where the timing of vaccination did not influence the proportion of positive titers to BRSV. However, steers in the present study had an average of 90% of steers with positive titers compared to only 20% of steers in Kirkpatrick et al. [30] that had positive titers to BRSV. This is likely due to steers in the present study receiving vaccination prior to the weaning event. Steers in the VAC treatment had increased (p = 0.01) BRSV titer concentrations compared to the titer concentrations of the NOVAC group (1.72 vs. 1.11). This is similar to Schumaher et al. [32], where delaying vaccination resulted in reduced titer concentrations compared to calves that received vaccination prior to weaning. However, this contradicts works by Fulton et al. [33], where titer concentrations were not different between vaccinated and nonvaccinated groups, and Step et al. [7], where calves were only vaccinated at weaning or were vaccinated at weaning followed by revaccination 11 d later. This is also different from Kirkpatrick et al. [30], where the BRSV log titers were different only at 42 d after weaning. Therefore, it appears that increased BRSV titer concentrations from weaning to throughout the receiving period may be dependent upon vaccination ≥ 30 d prior to the weaning event.

No treatment × day interactions or main effects (p > 0.05) were observed for BVD Type I and II concentrations. This disagrees with a 56 d trial by Richeson et al. [24], where there was a treatment × day interaction for BVD Type I and II titer concentrations between calves that received a respiratory and clostridial vaccine alone or in combination upon feedlot arrival. In the same trial, BVD Type I titer concentrations were also increased with respiratory vaccine administration upon arrival, which contradicts the present study where delaying vaccination did not influence (p = 0.44) BVD Type I titer concentrations (Figure 9) nor BVD Type II titer concentrations (Figure 10). This contradicts Fulton et al. [33], Kirkpatrick et al. [30], and Menanteau-Horta et al. [31], where increased titers for BVD Type I and II were observed in calves that had previous vaccination and were revaccinated. It is important to note that all steers in the present study had positive titers for BDV Type I and II. This differs from Kirkpatrick et al. [30], where vaccinated calves compared to nonvaccinated calves reported 64% vs. 3% and 83% vs. 3% positive titers for BVD Type I and II, respectively. However, it has been observed that steers receiving vaccinations prior to feedlot arrival and prior to a second booster vaccination had increased antibody titers compared to those that had delayed vaccine administration for BVD I and II [34] or BVD Type I, BRSV, PI₃, and bovine herpesvirus [32]. As all calves in the present study were vaccinated prior to their arrival at the feedlot, and either received vaccination or were not vaccinated upon arrival, this may help explain the lack of differences between treatments. This may also explain why all calves had adequate antibody titers throughout the duration of the study. Overall, it is evident from results of the present study and previous research that administering respiratory vaccinations prior to the weaning event increased the proportion of positive antibody titers and titer concentrations. The proportion of positive antibody titers and titer concentrations was further enhanced when administered a vaccine booster at weaning, with the exception of BVD Type I and II in the present study. The reason behind why there was greater response to vaccine administration compared to previous research may be a function of previous management of the steers resulting in steers being relatively unstressed and a low-risk population.

3.3. Growth Performance

Growth performance responses for the 42 d period were not influenced (p ≥ 0.10) by treatment (

Table 2. Growth performance responses for a 42 d study in previously vaccinated, newly weaned steers vaccinated for Infectious Bovine Rhinotracheitis, Bovine Virus Diarrhea Type I and II, Parainfluenza-3, Bovine Respiratory Syncytial Virus, and clostridial species upon arrival (VAC) or not vaccinated upon arrival (NOVAC).

Item	Treatment
	VAC	NOVAC	SEM	p-Value
Pens, n	5	5	-	-
Steers, n	35	35	-	-
Body weight (BW) 1, kg
Initial 1	254	254	1.33	0.59
d 21 2	276	274	2.09	0.34
d 42	293	292	2.86	0.60
Average daily gain (ADG), kg/d
Initial to d 21	1.01	0.94	0.072	0.38
d 21 to 42	0.83	0.86	0.064	0.67
Initial to d 42	0.92	0.90	0.055	0.72
Dry matter intake (DMI), kg/d
Initial to d 21	4.71	4.84	0.088	0.23
d 21 to 42	6.35	6.52	0.119	0.22
Initial to d 42	5.53	5.68	0.092	0.18
DMI % BW 3
Initial to d 21	1.78	1.84	0.031	0.13
d 21 to 42	2.24	2.32	0.034	0.07
Initial to d 42	2.02	2.09	0.028	0.07
Gain–feed (G:F) 4
Initial to d 21	0.214	0.196	0.0161	0.32
d 21 to 42	0.133	0.135	0.0081	0.90
Initial to d 42	0.168	0.161	0.0082	0.44
Applied Energetic Measures
Observed net energy of maintenance Mcal/kg	1.90	1.83	0.041	0.19
Observed net energy of gain Mcal/kg	1.26	1.20	0.036	0.19
Observed–expected DMI	0.90	0.94	0.025	0.19
Observed–expected ADG	1.23	1.14	0.055	0.18

¹ Average of BW collected on d 0 and d − 1. No shrink was applied to this BW. ² BW was shrunk 4% to account for digestive tract fill. ³ Calculated as DMI divided by BW. ⁴ Calculated as ADG divided by DMI.

). This was similar to a 56 d study by Richeson et al. [24], where no differences were observed in ADG between steers that received a respiratory and clostridial vaccine alone or in combination. This was also similar to a trial by Schumaher et al. [32], where no differences for BW and ADG were detected in calves vaccinated for respiratory diseases 15 d prior to weaning, at weaning, or 15 d after weaning. However, Arthington et al. [3] and Rodrigues et al. [4] reported reduced ADG, feed efficiency, and DMI when calves were vaccinated for respiratory diseases or not vaccinated upon arrival and vaccinated for respiratory diseases or administered saline solution 20 d after weaning, respectively.

In the present study, DMI as a percentage of BW tended (p < 0.07) to increase by 3.5% for the NOVAC group compared to the VAC group from d 21 to 42. Cumulative dry matter intake as a percentage of BW also tended (p < 0.07) to increase by 3.3% for the NOVAC group compared to the VAC group. However, both VAC and NOVAC steers had numerically similar observed to expected DMI based on applied energetic measures. Conflicting differences in performance based on vaccination timing in previous research have been suggested to be attributable to variations in management history [24]. The lack of differences between treatment groups in the present study helps to confirm that knowing vaccination history prior to feedlot arrival in newly weaned calves helps reduce variance in performance independent of vaccination administration in the next phase of production. This is further confirmed by the lack of differences in applied energetic values indicating that performance during the receiving period is similar between calves that are vaccinated prior to the weaning event. The administration of vaccines to calves while they are still with their dams allows adequate time for calves to develop immunologic protection prior to encountering potential threats of BRD and other pathogens when being transitioned to a backgrounding facility [2]. Therefore, knowing prior vaccination management may be useful to predict performance responses in calves coming into a backgrounding facility.

4. Conclusions

The current study may present some limitations. Sparse information is available in the literature about cattle with the same parameters on feedlot performance beyond the receiving phase. Long-term effects of vaccination timing in relatively unstressed, previously vaccinated calves on overall feedlot performance, health outcomes, and carcass characteristics would be beneficial.

Collectively, growth performance was unaffected by vaccination timing. As expected, vaccinated calves had increased overall antibody titer responses. Secondary vaccination provided additional antibody titers in circulation that could be available during times when calves could be immunocompromised. In the present study, calves were relatively unstressed and were also not naïve to pathogens as they all had received prior vaccination at the ranch. Thus, knowing the prior history of calves at receiving is important for determining vaccine protocols. The present study indicates that proper vaccination management and administration in the cow–calf sector did not hinder calf performance in the feedlot, regardless of vaccination administration timing at feedlot entry. However, producers need to consider what method is most applicable to their operation. This information may aid producers in making vaccine management decisions for receiving calves following the weaning event. Future research should focus on evaluating the long-term impacts of vaccination timing in relatively unstressed, previously vaccinated calves. Additionally, future research could also evaluate varying levels of stress at different times throughout the receiving period.