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The effect of weaning regimen on behavioral and production responses of beef calves
The Professional Animal Scientist 32 (2016):229–235; http://dx.doi.org/10.15232/pas.2015-01447 ©2016 American Registry of Professional Animal Scientists. All rights reserved.
T hone effect of weaning regimen behavioral and production responses of beef calves
B. I. Wiese,*† S. Hendrick,†1 J. M. Stookey,† K. S. Schwartzkopf-Genswein,‡ S. Li,§ J. C. Plaizier,§ and G. B. Penner*2 *Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK, S7N 5A8 Canada; †Department of Large Animal Clinical Sciences, University of Saskatchewan, Saskatoon, SK, S7N 5B4 Canada; ‡Agriculture and Agri-Food Canada, Lethbridge Research Centre, Lethbridge, AB, T1J 4B1 Canada; and §Department of Animal Science, University of Manitoba, Winnipeg, MB, R3T 2N2 Canada
ABSTRACT The objective of this experiment was to investigate the effect of method and timing of weaning on the behavior and DMI of calves throughout weaning, transportation, and a simulated receiving period. Cow-calf pairs (n = 30) housed in a common paddock were randomly assigned to 1 of 3 treatments: preweaning by abrupt removal of the dam 5 d before transportation (AW-P), 2-stage weaning using nose flaps applied 5 d before transportation (2-STG), or abrupt weaning on the day of transport (AW-T). The experiment included 5 d of baseline measurement (BLN), a 5-d weaning period (WN), 4.5 h of transportation (TRANS), and a simulated receiving period encompassing two 1-wk measurement periods (REC1 and REC2, respectively). During the REC1 and REC2, calves were housed by treatment (n = 3). Pedometers were used to measure lying time and steps from BLN to REC1. During d 1 to 3 of
Present address: Coaldale Veterinary Clinic, 141 Broxburn Blvd., Lethbridge, AB, Canada. 2 Corresponding author: greg.penner@ usask.ca 1
WN, 2-STG calves took fewer steps than AW-P calves but more than AW-T calves (P < 0.001). The AW-P calves spent less time lying than 2-STG and AW-T calves only on d 1 and 2 of WN (P < 0.001). During REC1, AW-T took more steps (P < 0.001) on d 1 and 2 than both AW-P and 2-STG. The AW-T calves spent the least time lying during REC1 (P < 0.01). Dry matter intake during receiving did not differ among treatments. These data suggests that both method and timing of weaning affect behavioral responses during a simulated receiving period but do not affect DMI. Key words: beef cattle, behavior, newly received cattle, weaning
INTRODUCTION The combined stress of weaning, marketing, and transportation contributes greatly to decreased performance of newly received feedlot cattle (Loerch and Fluharty, 1999; Step et al., 2008). Therefore, minimizing weaning stress may be a strategy to improve health and performance of newly received calves. Two-stage weaning is suggested as an alterna-
tive to abrupt weaning as a way to reduce weaning stress for cows and calves (Haley et al., 2005). Research has reported that 2-stage weaning, through the application of nose flaps to prevent suckling before removal from the dam, reduces the number of vocalizations and steps on the day of weaning relative to abruptly weaning of calves (Haley et al., 2005; Loberg et al., 2008; Enríquez et al., 2010). In terms of performance, calf ADG is not reduced or is moderately improved in the short term by 2-stage weaning (Haley et al., 2005; Enríquez et al., 2010). Moreover, calves weaned using a 2-stage approach spend 23% more time eating (Haley et al., 2005) than abruptly weaned calves. Unfortunately, previous experiments have an inherent confounding between weaning method and time because all dams were removed on the same day (Haley et al., 2005; Enríquez et al., 2011). Thus, past research compared responses of calves after removal of the dams, and consequently, it is not clear whether the benefits reported for 2-stage weaning are due to method of weaning or timing of weaning relative to shipping. Additionally, previ-
230 ous experiments have not confirmed whether method of weaning affects DMI after weaning, despite Haley et al. (2005) reporting an increase in time spent eating. We hypothesized that calves weaned using the 2-stage method will show less behavioral indications of stress and have a greater DMI during a simulated receiving period than their abruptly weaned counterparts. Moreover, we hypothesized that part of the benefit from the 2-stage weaning approach is related to the timing of weaning relative to shipping. The objective of the current experiment was to investigate the effects of weaning method and timing of weaning on the behavioral responses of calves before, during, and after weaning and their DMI in a simulated receiving period.
MATERIALS AND METHODS Animal Husbandry, Experimental Design, and Treatments The use of cows and calves in this experiment was approved by the University of Saskatchewan Animal Research Ethics Board (protocol number 20100021) and was in accordance with the guidelines of the Canadian Council of Animal Care. Thirty multiparous Hereford cows nursing male calves born between March 14 and April 11, 2012, and sired by Gelbvieh, Red Angus, or Simmental bulls, from the Goodale Research Farm at the University of Saskatchewan, were selected to minimize variation in age, sex, and BW. At birth, all calves were given a 1-mL i.m. injection of vitamins A and D (5,000 kIU/mL vitamin A and 75 kIU/mL vitamin D; Vitamin AD500, Bimeda–MTC Animal Health Inc., Cambridge, ON, Canada) and 1 mL of vitamin E and selenium (135 IU/mL and 3 mg/mL, respectively; Dystosel, Pfizer Canada Inc., Kirkland, QC, Canada) and were vaccinated subcutaneously at 6 to 8 wk of age with a multivalent viral vaccine for bovine viral diarrhea virus, infectious bovine rhinotracheitis, parainfluenza 3, and bovine respira-
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tory syncytial virus (Starvac 4 Plus, Novartis Animal Health Canada Inc., Mississauga, ON, Canada) and with a 9-way clostridia vaccine (Covexin Plus, Merck Animal Health, Montreal, QC, Canada). All calves were castrated by banding by an experienced technician at 1 d of age. At the start of the experiment, calves were (mean ± SD) 162 ± 8.7 d old and weighed 234.3 ± 17.8 kg. All cow-calf pairs were housed in a common paddock for 5 d before the start of the experiment and had free access to hay and water. On a DM basis, the nutrient analysis of the grass-hay was (mean ± SD) 91.9% DM, 12.2 ± 0.85% CP, 59.5 ± 0.07% NDF, 1.4 ± 0.17% ether extract, and 7.4 ± 0.05% ash. The experiment consisted of 5 distinct periods: a 5-d baseline period (BLN), a 5-d weaning period (WN), a transportation event (TRANS), and 2 consecutive weeks of a simulated receiving period where calves were housed in drylot pens and fed using fence-line bunk feeders (REC1 and REC2). During BLN and WN, cow-calf pairs were housed in a common pen and had free access to grass hay (same as described above). Calves were stratified by BW and within strata were randomly assigned to 1 of 3 treatments such that initial calf BW was balanced across treatments. Treatments, applied during WN, included (1) a 2-stage weaning approach (2-STG) where each calf was fitted with a plastic nose flap that prevented suckling (JDA Livestock Innovations Ltd., Saskatoon, SK, Canada) on d 1 of WN (5 d before TRANS) but were returned back to the common pen in the presence of their dam throughout the WN period, (2) abrupt weaning of calves by removing their dam on d 1 of WN, which also corresponds to 5 d before the TRANS event (AW-P), and (3) abrupt weaning of calves by physical separation from their dam on the day of TRANS (AW-T). Although AW-P calves were physically separated from their dam, they were housed in the same pen as 2-STG and AW-T calves and dams. It is important to note that we
did not verify whether AW-P calves attempted to or successfully suckled from the remaining dams in the pen. To ensure that processing calves did not confound the response, all calves were handled on each day. On the day of TRANS, all calves were loaded into a stock trailer (2.4 m × 9.8 m) with straw for bedding. Calves were transported for 4.5 h (250 km) to mimic shipping and returned to Goodale Farm (Saskatoon, SK). Calves were then grouped by treatment and placed into 1 of 3 pens measuring 23 × 30.5 m. This resulted in 3 pens for each treatment (2 pens with 3 calves and 1 pen with 4 calves). Calves were penned by treatment to facilitate measurement of DMI as affected by the weaning treatment, and as such pen was considered the experimental unit for REC1 and REC2, During REC1 and REC2, steers were fed a diet consisting of 45% barley silage, 45% barley grain, and 10% of a mineral and vitamin pellet on a DM basis, formulated to meet nutrient requirements (NRC, 2000). Feed samples were collected twice weekly from the stored feed immediately before feeding, and the DM content was determined using a forced-air oven at 55°C. If necessary, diets were adjusted to maintain the specified forage-to-concentrate ratio. Feed samples were analyzed at Cumberland Valley Analytical Services (Hagerstown, WI) for DM, ash, CP, NDF, ADF, ether extract, starch, Ca, and P using wet chemistry. A detailed description of the procedures was described by Rosser et al. (2013). The composition of the diet on a DM basis was (mean ± SD) 57.4 ± 0.66% DM, 91.8 ± 0.27% OM, 14.0 ± 0.01% CP, 37.1 ± 0.30% NDF, 23.5 ± 0.19% ADF, 2.6 ± 0.09% ether extract, 32.2 ± 0.02% starch, 39.7 ± 0.50% nonfiber carbohydrate, 0.70 ± 0.03% Ca, and 0.41 ± 0.002% P. Ionophores were not used in this experiment. The amounts of feed offered and refused for each pen were determined daily, as was refusal DM content. Dry matter intake was calculated as the difference between the amount of DM offered and refused.
Method and timing of weaning
Data and Sample Collection Measurement of Calf Activity. Seventeen of the 30 calves (n = 6, 6, and 5 for 2-STG, AW-P, and AW-T, respectively) were fitted with a pedometer (IceTag3D; Ice Robotics Ltd., South Queensferry, Scotland, UK) on the right front leg to measure calf activity by the magnitude of acceleration in 3 dimensions at 16 Hz. Pedometers were administered on d 1 of BLN and removed on d 7 of REC1. Three of the 17 loggers failed before any data were collected, leaving six 2-STG calves, 4 AW-T calves, and 4 AW-P calves with complete activity measurements. A 1-s interval between consecutive measurements was used for data collection, and data were summarized based on 1-min intervals using a software program (IceManager Desktop Software, Ice Robotics Ltd.) to determine the amount of time spent lying and the number of steps per day. BW and Blood Collection. Calves were weighed individually on d 1 of BLN, d 1 of WN, immediately before transport (BTRANS), upon arrival after transport (ATRANS), on d 1 of REC1 and REC2, and at the end of REC2. At weighing, a blood sample was collected into two 10-mL evacuated tubes containing Na-heparin (158 IU units) and silica act clot activator (BD, Franklin Lakes, NJ) for plasma and serum, respectively, except on d 1 of BLN, where only serum was collected. Plasma tubes were placed immediately on ice, and serum tubes were allowed to clot at room temperature. All samples were transported to the laboratory within 1 h and centrifuged at 2,500 × g for 15 min at 4°C. Serum and plasma samples were stored at −20°C until analysis. Plasma glucose was measured using a glucose oxidase/peroxidase enzyme preparation (No. P7119; SigmaAldrich, Oakville, ON, Canada) and dianisidine dihydrochloride (No. D3252–5g Sigma-Aldrich). Absorbance was determined with a plate reader (SpectraMax PLUS384, Molecular Devices Corp., Sunnyvale, CA)
at a wavelength of 450 nm. Plasma insulin was measured using a commercial ELISA kit (Mercodia, Uppsala, Sweden). Serum nonesterified fatty acid (NEFA) concentration was measured using a commercial colorimetric kit (NEFA-HR2; Wako Diagnostics, Richmond, VA) modified for a plate reader. Serum BHBA was measured based on the oxidation of BHBA and the resulting color change induced by the reduction of nicotinamide adenine dinucleotide (No.127841, Roche, Mississauga, Ontario, Canada). Plasma samples collected BTRANS and ATRANS were used for the analysis of serum amyloid A and lipopolysaccharide binding protein as described by Li et al. (2012).
Statistical Analysis One AW-P calf was removed from the experiment because of health reasons unrelated to the treatment. Data were analyzed independently for each period (i.e., BLN, WN, BTRANS, ATRANS, REC1, and REC2) using the Mixed Model in SAS (SAS Institute Inc., Cary, NC; version 9.3). The model included the fixed effect of treatment and day and the 2-way interaction, with day included as a repeated measure. The covariance error structure that yielded the lowest Akaike’s and Bayesian information criterion for each variable was used, and when the F-test was significant, the Bonferroni correction was applied and used to identify means that differed (P < 0.05). Tendencies are discussed when 0.1 > P > 0.05. For all measurements except DMI, calf was considered to be the experimental unit. For DMI, pen was considered to be the experimental unit.
RESULTS AND DISCUSSION Abrupt weaning was shown to be stressful for calves, as measured by both physiological (Lynch et al., 2010; Kim et al., 2011) and behavioral (Haley et al., 2005) changes. Adopting practices that improve welfare by reducing stress at weaning should be an ongoing pursuit for stakeholders
231 in the beef cattle industry. Accordingly, several methods such as fenceline weaning (Price et al., 2003) and the use of 2-stage weaning using nose flaps (Haley et al., 2005) to prevent suckling while in the presence of the dam were evaluated as strategies to reduce the stress at weaning. Previous experiments have reported that abrupt weaning increases walking distance (Lay et al., 1998; Haley et al., 2005; Enríquez et al., 2010) and decreases the time spent lying relative to weaning strategies where the calf has direct contact with the dam during the weaning process. In the current experiment, the number of steps taken by calves during BLN tended (P = 0.061) to differ, with 2-STG calves taking 2,778 steps/d, AW-T calves taking 2,616 steps/d, and AW-P taking 2,007 steps/d (data not shown). It is not clear why the number of steps would differ before application of treatments. However, the response is likely due to normal individual variation, especially because lying time did not differ (P = 0.20) among treatments during BLN, with an average of 14.4 h spent lying each day (Figure 1). The concentration of BHBA was greater during BLN for AW-T (P = 0.010) than for 2-STG and AW-P, which did not differ (Table 1). Baseline insulin and NEFA did not differ between treatments with P = 0.93 and 0.55, respectively. Upon initiation of the WN period, AW-P calves took twice as many steps on d 2 of WN than AW-T and 2-STG calves (P < 0.001; Figure 1) and spent less time lying (P < 0.001) on d 1 and 2 of WN compared with the other treatment groups, which did not differ. This suggests that despite both 2-STG and AW-P calves losing access to milk on the same day, it was the separation from the dam that caused the AW-P calves to alter their behavior. This is supported by the lack of difference in time spent lying and number of steps taken between 2-STG and nonweaned calves (AW-T) during WN. It appears that implementing the 2-STG weaning system allows calves to express similar behaviors as
232 nonweaned calves, with the exception of suckling. Interestingly, pretransport serum NEFA was greater for 2-STG than AW-T (P = 0.017; Table 1), which suggests that 2-STG calves may spend more time attempting to suckle rather than eating, leading to negative energy balance and mobilization of body fat. However, serum BHBA, plasma glucose, and insulin did not differ between treatments (P > 0.1). Although acute-phase proteins such as serum amyloid A were reported to be elevated after weaning (Kim et al., 2011), we were unable to detect a treatment difference for the concentrations of serum amyloid A and lipopolysaccharide binding protein (P > 0.1) after weaning (BTRANS and ATRANS). This suggests that at the physiological level, all 3 treatments were affected equally by the stresses of weaning. There were no behavioral differences detected between any of the treatments from d 3 of WN onward, which is consistent with the findings of Lambertz et al. (2014), and suggests that the positive
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effect of 2-stage weaning is short in duration. These results support that abrupt weaning is more stressful for calves than weaning in 2 stages but suggest that weaning with the use of nose flaps is not stress free. Likely, the benefit of 2-stage weaning is due to dividing the stress into 2 smaller stressors, namely the loss of milk followed by loss of the dam (Weary et al., 2008). The transportation event in this experiment imposed a physiological stressor as indicated by BW loss (shrink) ranging between 8.9 and 9.4 kg/4 h without differences among treatments (Table 2). Past experiments have indicated that transportation following weaning increased the concentrations of acute-phase proteins such as serum amyloid A and haptoglobin (Arthington et al., 2003). Moreover, plasma glucose is expected to increase after fasting coupled with transportation (Phillips et al., 1991). We did not see differences for BHBA, NEFA, insulin, serum amyloid A, or lipopolysaccharide binding protein.
There was, however, a tendency for blood glucose concentration to be less for 2-STG calves than the other 2 treatments (P = 0.054; Table 1) after transportation. It should be noted that the transportation event was only 4.5 h in duration and calves were not fasted before transportation, which may explain the differential response for the current experiment and a previous experiment (Arthington et al., 2003). There were no differences (P > 0.1) among treatments for plasma or serum metabolites and insulin during REC1 or REC2; however, it should be noted that calves were resorted, but were not mixed with new cohorts, and therefore the stress experienced may not have been severe enough to induce marked changes in metabolism and inflammatory responses. Dry matter intake during REC1 was influenced by day (P < 0.001), with DMI decreasing from d 1 to 2, but then increasing from d 3 to reach a maximum of 7.9 kg on d 5 (Figure 2). There was a tendency for
Figure 1. Effect of weaning method and timing of weaning on the number of steps and lying behavior of steer calves. Calves were exposed to 1 of 3 treatments: (1) abruptly weaned on d 1 (AW-P; black bars) of the period designated weaning (WN), (2) weaned by preventing suckling on d 1 of WN using nose flaps (2-STG; gray bars), or (3) abruptly weaned (AW-T; white bars) on d 1 of receiving. Bars with diagonal lines in panels A and D indicate the overall effect of day as the treatment and treatment × period interactions were not significant during baseline (BLN) measurements. Panels B and E report results during WN, and panels C and F report results during recovery period 1 (REC1). Columns with different letters within a panel indicate values that differ (P < 0.05). Error bars depict the SEM.
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DMI to differ between treatments by day (P = 0.068). Dry matter intake of 2-STG calves followed the same pattern as the day effect, whereas DMI of AW-T calves was least on d 1 and 2 before increasing to d 4 and AW-P calves showed only subtle increases in DMI from d 1 to 5. There were no differences found in REC2 (data not shown), with DMI ranging between 7.2 and 7.8 kg/d. Thus, our data are only partially supportive of past experiments reporting a reduc-
tion in time spent at the bunk for abruptly weaned calves relative to 2-STG calves in response to weaning (Haley et al., 2005). We were unable to detect differences (P > 0.10) for ADG during REC1 or REC2 (Table 2), suggesting that performance is not affected by weaning method. Unfortunately, by using pen as the experimental unit, the power of this portion of the experiment was limited. Therefore, although results suggest that DMI and ADG during the receiv-
ing period are not affected by weaning method, caution must be taken with these findings. In contrast, the timing of the weaning event had an effect on the behavioral responses of calves during a simulated receiving period. On d 1 and 2 of REC1, AW-T calves took more steps than AW-P and 2-STG calves (P < 0.001) and spent less time lying on d 1 of REC1 than both 2-STG and AW-P calves (P < 0.001). On d 2, AW-T calves spent less time
Table 1. Effect of weaning method and timing of weaning on blood metabolites, insulin, and acute-phase proteins in steer calves Treatment2 Variable1
AW-P
2-STG
AW-T
N BLN BHBA, mg/dL Insulin, μg/L NEFA, μEq/mL BTRANS BHBA, mg/dL Glucose, mg/dL Insulin, μg/L NEFA, μEq/mL Serum amyloid A, mg/mL Lipopolysaccharide binding protein, mg/mL ATRANS BHBA, mg/dL Glucose, mg/dL Insulin, μg/L NEFA, μEq/mL Serum amyloid A, mg/mL Lipopolysaccharide binding protein, mg/mL REC1 BHBA, mg/dL Glucose, mg/dL Insulin, μg/L NEFA, μEq/mL REC2 BHBA, mg/dL Glucose, mg/dL Insulin, μg/L NEFA, μEq/mL
9 13.2b 0.19 273 11.3 72.6 0.17 414ab 63 7.5 9.8 83 0.17 504 58 7.6 12.3 80.6 0.13 157 10.6 79.6 0.14 228
10 13.8b 0.22 232 12.7 76.7 0.12 526a 128 9.1 10.6 72.2 0.12 583 148 9.9 12.2 78.7 0.12 165 11.0 76.8 0.20 266
10 17.6a 0.23 252 11.8 82.0 0.15 229b 107 12.4 11.2 82.6 0.16 419 132 13.1 14.2 81.7 0.21 190 12.2 81.7 0.21 190
SEM3
1.0 0.06 27 0.9 3.8 0.03 71 36 2.5 1.3 3.6 0.03 68 43 2.6 1.0 3.8 0.04 33 1.0 4.6 0.04 37
P-value
0.006 0.91 0.58 0.56 0.23 0.34 0.016 0.46 0.36 0.74 0.064 0.30 0.21 0.30 0.34 0.27 0.84 0.22 0.77 0.45 0.74 0.50 0.36
Means within a row with different superscripts differ from each other (P < 0.05). The experiment consisted of 4 measurement periods: baseline (BLN, d −10 to −6 relative to transport), weaning (WN, d −5 to −1 relative to transport), transportation (on the day of weaning, steers were loaded on a trailer and transported for 4.5 h), and a simulated 2-wk receiving period (REC1 and REC2). Blood samples and BW were collected before transportation (BTRANS) and upon arrival after transportation (ATRANS). 2 Calves were exposed to 1 of 3 treatments: (1) abruptly weaned on d 1 (AW-P) of the period designated weaning (WN), (2) weaned by preventing suckling on d 1 of WN using nose flaps (2-STG), or (3) abruptly weaned (AW-T) on d 1 of receiving. 3 The largest SEM is reported. a,b 1
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lying than the AW-P calves (13.3 vs. 16.7 h) but did not differ from 2-STG (15.2 h), which in turn did not differ from AW-P calves. Therefore, calves weaned and transported on the same day appear to exhibit more behavioral indications of stress than those weaned before transport. This finding suggests that part of the diminished stress response observed for 2-STG weaning relative to abrupt weaning in previous experiments (Haley et al., 2005; Enríquez et al., 2011) may in fact be related to the timing of the weaning event. In the current experiment there were no differences in the number of steps taken by calves from d 3 of REC 1 onward, with less than 2,000 steps/d across treatments (Figure 1). Time spent lying did not differ among treatments from d 2 onward, with all calves spending approximately 15.0 h/d lying (Figure 1), supporting previous results that the stress due to weaning appears to be transient, regardless of method of weaning.
Figure 2. Effect of day within recovery period 1 (REC1) and recovery period 2 (REC2) on DMI after calves were (1) abruptly weaned and separated from their dam 5 d prior (AW-P) to the start of REC1, (2) weaned 5 d prior by preventing suckling using nose flaps (2-STG), or (3) abruptly weaned (AW-T) on d 1 of REC1. For REC1 (panel A), P-values for treatment, day, and the treatment × day interaction were 0.96, <0.001, and 0.068, respectively. For REC2 (panel B), P-values for treatment, day, and the treatment × day interaction were 0.96, 0.10, and 0.92, respectively. Means with different letters within a panel indicate values that differ (P < 0.05). Error bars depict the SEM.
The results of the present experiment indicated that regardless of the weaning method used, weaning calves before transportation minimizes behavioral indicators of stress in a simulated receiving period but does
Table 2. Effect of weaning method and timing of weaning on BW and ADG of steers Treatment2 Variable1
AW-P
2-STG
AW-T
SEM3
P-value
BLN, kg BTRANS, kg ATRANS, kg Shrink,4 kg REC1 BW, kg ADG, kg/d REC2 BW, kg ADG, kg/d
236 233 225 8.98 245 2.92 248 0.51
234 244 235 9.43 254 2.75 255 0.19
235 234 231 9.03 248 2.41 255 0.99
6 7 7 1.72 8 0.39 8 0.37
0.99 0.57 0.57 0.98 0.71 0.65 0.80 0.32
The experiment consisted of 4 measurement periods: baseline (BLN, d −10 to −6 relative to transport), weaning (WN, d −5 to −1 relative to transport), transportation (TRANS; on the day of weaning steers were loaded on a trailer and transported for 4.5 h), and a simulated 2-wk receiving period (REC1 and REC2). Blood samples and BW were collected before transportation (BTRANS) and upon arrival after transportation (ATRANS). 2 Calves were exposed to 1 of 3 treatments: (1) abruptly weaned on d 1 (AW-P) of the period designated weaning (WN), (2) weaned by preventing suckling on d 1 of WN using nose flaps (2-STG), or (3) abruptly weaned (AW-T) on d 1 of receiving. 3 The largest SEM is reported. 4 The difference between BTRANS and ATRANS BW. 1
not improve DMI or ADG. Additionally, the use of a 2-stage weaning approach mitigated behavioral changes in response to the weaning process.
IMPLICATIONS The results of this experiment support previous studies indicating that use of a 2-stage weaning approach reduces behavioral indicators of stress associated with weaning in calves. These findings further suggest that part of the benefit observed with 2-stage weaning may be attributable to calves being weaned before transport. Furthermore, weaning calves before transportation, regardless of method, can be effective in reducing behavioral indicators of stress upon arrival at the feedlot but may not affect performance.
ACKNOWLEDGMENTS Funding for the project was provided through the Natural Sciences and Engineering Research Council of Canada (NSERC) ENGAGE program and JDA Livestock Solutions Inc. (Saskatoon, SK, Canada). The authors would like to thank R. Kanafany Guzman, P. Górka, G. Gratton, and M. E. Walpole at the University of Saskatchewan for assistance with
Method and timing of weaning
data and sample collection and analysis, and F. Brown and C. Goldhawk at Agriculture and Agri-Food Canada for assistance with the pedometer measurements.
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235 NRC. 2000. Nutrient Requirements of Beef Cattle: Update. 7th ed. Natl. Acad. Press, Washington, DC. Phillips, W. A., P. E. Juniewicz, and D. L. VonTungeln. 1991. The effect of fasting, transit plus fasting, and administration of adrenocorticotropic hormone on the source and amount of weight lost by feeder steers of different ages. J. Anim. Sci. 69:2342–2348. Price, E. O., J. E. Harris, R. E. Borgward, M. L. Sween, and J. M. Connor. 2003. Fenceline contact of beef calves with their dams at weaning reduces the negative effects of separation on behavior and growth rate. J. Anim. Sci. 81:116–121. Rosser, C. L., P. Gorka, A. D. Beattie, H. C. Block, J. J. McKinnon, H. A. Lardner, and G. B. Penner. 2013. Effect of maturity at harvest on yield, chemical composition, and in situ degradability for annual cereals used for swath grazing. J. Anim. Sci. 91:3815–3826. Step, D. L., C. R. Krehbiel, H. A. DePra, J. J. Cranston, R. W. Fulton, J. G. Kirkpatrick, D. R. Gill, M. E. Payton, M. A. Montelongo, and A. W. Confer. 2008. Effects of commingling beef calves from different sources and weaning protocols during a forty-two-day receiving period on performance and bovine respiratory disease. J. Anim. Sci. 86:3146– 3158. Weary, D. M., J. Jasper, and M. J. Hötzel. 2008. Understanding weaning distress. Appl. Anim. Behav. Sci. 110:24–41.
T hone effect of weaning regimen behavioral and production responses of beef calves
B. I. Wiese,*† S. Hendrick,†1 J. M. Stookey,† K. S. Schwartzkopf-Genswein,‡ S. Li,§ J. C. Plaizier,§ and G. B. Penner*2 *Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK, S7N 5A8 Canada; †Department of Large Animal Clinical Sciences, University of Saskatchewan, Saskatoon, SK, S7N 5B4 Canada; ‡Agriculture and Agri-Food Canada, Lethbridge Research Centre, Lethbridge, AB, T1J 4B1 Canada; and §Department of Animal Science, University of Manitoba, Winnipeg, MB, R3T 2N2 Canada
ABSTRACT The objective of this experiment was to investigate the effect of method and timing of weaning on the behavior and DMI of calves throughout weaning, transportation, and a simulated receiving period. Cow-calf pairs (n = 30) housed in a common paddock were randomly assigned to 1 of 3 treatments: preweaning by abrupt removal of the dam 5 d before transportation (AW-P), 2-stage weaning using nose flaps applied 5 d before transportation (2-STG), or abrupt weaning on the day of transport (AW-T). The experiment included 5 d of baseline measurement (BLN), a 5-d weaning period (WN), 4.5 h of transportation (TRANS), and a simulated receiving period encompassing two 1-wk measurement periods (REC1 and REC2, respectively). During the REC1 and REC2, calves were housed by treatment (n = 3). Pedometers were used to measure lying time and steps from BLN to REC1. During d 1 to 3 of
Present address: Coaldale Veterinary Clinic, 141 Broxburn Blvd., Lethbridge, AB, Canada. 2 Corresponding author: greg.penner@ usask.ca 1
WN, 2-STG calves took fewer steps than AW-P calves but more than AW-T calves (P < 0.001). The AW-P calves spent less time lying than 2-STG and AW-T calves only on d 1 and 2 of WN (P < 0.001). During REC1, AW-T took more steps (P < 0.001) on d 1 and 2 than both AW-P and 2-STG. The AW-T calves spent the least time lying during REC1 (P < 0.01). Dry matter intake during receiving did not differ among treatments. These data suggests that both method and timing of weaning affect behavioral responses during a simulated receiving period but do not affect DMI. Key words: beef cattle, behavior, newly received cattle, weaning
INTRODUCTION The combined stress of weaning, marketing, and transportation contributes greatly to decreased performance of newly received feedlot cattle (Loerch and Fluharty, 1999; Step et al., 2008). Therefore, minimizing weaning stress may be a strategy to improve health and performance of newly received calves. Two-stage weaning is suggested as an alterna-
tive to abrupt weaning as a way to reduce weaning stress for cows and calves (Haley et al., 2005). Research has reported that 2-stage weaning, through the application of nose flaps to prevent suckling before removal from the dam, reduces the number of vocalizations and steps on the day of weaning relative to abruptly weaning of calves (Haley et al., 2005; Loberg et al., 2008; Enríquez et al., 2010). In terms of performance, calf ADG is not reduced or is moderately improved in the short term by 2-stage weaning (Haley et al., 2005; Enríquez et al., 2010). Moreover, calves weaned using a 2-stage approach spend 23% more time eating (Haley et al., 2005) than abruptly weaned calves. Unfortunately, previous experiments have an inherent confounding between weaning method and time because all dams were removed on the same day (Haley et al., 2005; Enríquez et al., 2011). Thus, past research compared responses of calves after removal of the dams, and consequently, it is not clear whether the benefits reported for 2-stage weaning are due to method of weaning or timing of weaning relative to shipping. Additionally, previ-
230 ous experiments have not confirmed whether method of weaning affects DMI after weaning, despite Haley et al. (2005) reporting an increase in time spent eating. We hypothesized that calves weaned using the 2-stage method will show less behavioral indications of stress and have a greater DMI during a simulated receiving period than their abruptly weaned counterparts. Moreover, we hypothesized that part of the benefit from the 2-stage weaning approach is related to the timing of weaning relative to shipping. The objective of the current experiment was to investigate the effects of weaning method and timing of weaning on the behavioral responses of calves before, during, and after weaning and their DMI in a simulated receiving period.
MATERIALS AND METHODS Animal Husbandry, Experimental Design, and Treatments The use of cows and calves in this experiment was approved by the University of Saskatchewan Animal Research Ethics Board (protocol number 20100021) and was in accordance with the guidelines of the Canadian Council of Animal Care. Thirty multiparous Hereford cows nursing male calves born between March 14 and April 11, 2012, and sired by Gelbvieh, Red Angus, or Simmental bulls, from the Goodale Research Farm at the University of Saskatchewan, were selected to minimize variation in age, sex, and BW. At birth, all calves were given a 1-mL i.m. injection of vitamins A and D (5,000 kIU/mL vitamin A and 75 kIU/mL vitamin D; Vitamin AD500, Bimeda–MTC Animal Health Inc., Cambridge, ON, Canada) and 1 mL of vitamin E and selenium (135 IU/mL and 3 mg/mL, respectively; Dystosel, Pfizer Canada Inc., Kirkland, QC, Canada) and were vaccinated subcutaneously at 6 to 8 wk of age with a multivalent viral vaccine for bovine viral diarrhea virus, infectious bovine rhinotracheitis, parainfluenza 3, and bovine respira-
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tory syncytial virus (Starvac 4 Plus, Novartis Animal Health Canada Inc., Mississauga, ON, Canada) and with a 9-way clostridia vaccine (Covexin Plus, Merck Animal Health, Montreal, QC, Canada). All calves were castrated by banding by an experienced technician at 1 d of age. At the start of the experiment, calves were (mean ± SD) 162 ± 8.7 d old and weighed 234.3 ± 17.8 kg. All cow-calf pairs were housed in a common paddock for 5 d before the start of the experiment and had free access to hay and water. On a DM basis, the nutrient analysis of the grass-hay was (mean ± SD) 91.9% DM, 12.2 ± 0.85% CP, 59.5 ± 0.07% NDF, 1.4 ± 0.17% ether extract, and 7.4 ± 0.05% ash. The experiment consisted of 5 distinct periods: a 5-d baseline period (BLN), a 5-d weaning period (WN), a transportation event (TRANS), and 2 consecutive weeks of a simulated receiving period where calves were housed in drylot pens and fed using fence-line bunk feeders (REC1 and REC2). During BLN and WN, cow-calf pairs were housed in a common pen and had free access to grass hay (same as described above). Calves were stratified by BW and within strata were randomly assigned to 1 of 3 treatments such that initial calf BW was balanced across treatments. Treatments, applied during WN, included (1) a 2-stage weaning approach (2-STG) where each calf was fitted with a plastic nose flap that prevented suckling (JDA Livestock Innovations Ltd., Saskatoon, SK, Canada) on d 1 of WN (5 d before TRANS) but were returned back to the common pen in the presence of their dam throughout the WN period, (2) abrupt weaning of calves by removing their dam on d 1 of WN, which also corresponds to 5 d before the TRANS event (AW-P), and (3) abrupt weaning of calves by physical separation from their dam on the day of TRANS (AW-T). Although AW-P calves were physically separated from their dam, they were housed in the same pen as 2-STG and AW-T calves and dams. It is important to note that we
did not verify whether AW-P calves attempted to or successfully suckled from the remaining dams in the pen. To ensure that processing calves did not confound the response, all calves were handled on each day. On the day of TRANS, all calves were loaded into a stock trailer (2.4 m × 9.8 m) with straw for bedding. Calves were transported for 4.5 h (250 km) to mimic shipping and returned to Goodale Farm (Saskatoon, SK). Calves were then grouped by treatment and placed into 1 of 3 pens measuring 23 × 30.5 m. This resulted in 3 pens for each treatment (2 pens with 3 calves and 1 pen with 4 calves). Calves were penned by treatment to facilitate measurement of DMI as affected by the weaning treatment, and as such pen was considered the experimental unit for REC1 and REC2, During REC1 and REC2, steers were fed a diet consisting of 45% barley silage, 45% barley grain, and 10% of a mineral and vitamin pellet on a DM basis, formulated to meet nutrient requirements (NRC, 2000). Feed samples were collected twice weekly from the stored feed immediately before feeding, and the DM content was determined using a forced-air oven at 55°C. If necessary, diets were adjusted to maintain the specified forage-to-concentrate ratio. Feed samples were analyzed at Cumberland Valley Analytical Services (Hagerstown, WI) for DM, ash, CP, NDF, ADF, ether extract, starch, Ca, and P using wet chemistry. A detailed description of the procedures was described by Rosser et al. (2013). The composition of the diet on a DM basis was (mean ± SD) 57.4 ± 0.66% DM, 91.8 ± 0.27% OM, 14.0 ± 0.01% CP, 37.1 ± 0.30% NDF, 23.5 ± 0.19% ADF, 2.6 ± 0.09% ether extract, 32.2 ± 0.02% starch, 39.7 ± 0.50% nonfiber carbohydrate, 0.70 ± 0.03% Ca, and 0.41 ± 0.002% P. Ionophores were not used in this experiment. The amounts of feed offered and refused for each pen were determined daily, as was refusal DM content. Dry matter intake was calculated as the difference between the amount of DM offered and refused.
Method and timing of weaning
Data and Sample Collection Measurement of Calf Activity. Seventeen of the 30 calves (n = 6, 6, and 5 for 2-STG, AW-P, and AW-T, respectively) were fitted with a pedometer (IceTag3D; Ice Robotics Ltd., South Queensferry, Scotland, UK) on the right front leg to measure calf activity by the magnitude of acceleration in 3 dimensions at 16 Hz. Pedometers were administered on d 1 of BLN and removed on d 7 of REC1. Three of the 17 loggers failed before any data were collected, leaving six 2-STG calves, 4 AW-T calves, and 4 AW-P calves with complete activity measurements. A 1-s interval between consecutive measurements was used for data collection, and data were summarized based on 1-min intervals using a software program (IceManager Desktop Software, Ice Robotics Ltd.) to determine the amount of time spent lying and the number of steps per day. BW and Blood Collection. Calves were weighed individually on d 1 of BLN, d 1 of WN, immediately before transport (BTRANS), upon arrival after transport (ATRANS), on d 1 of REC1 and REC2, and at the end of REC2. At weighing, a blood sample was collected into two 10-mL evacuated tubes containing Na-heparin (158 IU units) and silica act clot activator (BD, Franklin Lakes, NJ) for plasma and serum, respectively, except on d 1 of BLN, where only serum was collected. Plasma tubes were placed immediately on ice, and serum tubes were allowed to clot at room temperature. All samples were transported to the laboratory within 1 h and centrifuged at 2,500 × g for 15 min at 4°C. Serum and plasma samples were stored at −20°C until analysis. Plasma glucose was measured using a glucose oxidase/peroxidase enzyme preparation (No. P7119; SigmaAldrich, Oakville, ON, Canada) and dianisidine dihydrochloride (No. D3252–5g Sigma-Aldrich). Absorbance was determined with a plate reader (SpectraMax PLUS384, Molecular Devices Corp., Sunnyvale, CA)
at a wavelength of 450 nm. Plasma insulin was measured using a commercial ELISA kit (Mercodia, Uppsala, Sweden). Serum nonesterified fatty acid (NEFA) concentration was measured using a commercial colorimetric kit (NEFA-HR2; Wako Diagnostics, Richmond, VA) modified for a plate reader. Serum BHBA was measured based on the oxidation of BHBA and the resulting color change induced by the reduction of nicotinamide adenine dinucleotide (No.127841, Roche, Mississauga, Ontario, Canada). Plasma samples collected BTRANS and ATRANS were used for the analysis of serum amyloid A and lipopolysaccharide binding protein as described by Li et al. (2012).
Statistical Analysis One AW-P calf was removed from the experiment because of health reasons unrelated to the treatment. Data were analyzed independently for each period (i.e., BLN, WN, BTRANS, ATRANS, REC1, and REC2) using the Mixed Model in SAS (SAS Institute Inc., Cary, NC; version 9.3). The model included the fixed effect of treatment and day and the 2-way interaction, with day included as a repeated measure. The covariance error structure that yielded the lowest Akaike’s and Bayesian information criterion for each variable was used, and when the F-test was significant, the Bonferroni correction was applied and used to identify means that differed (P < 0.05). Tendencies are discussed when 0.1 > P > 0.05. For all measurements except DMI, calf was considered to be the experimental unit. For DMI, pen was considered to be the experimental unit.
RESULTS AND DISCUSSION Abrupt weaning was shown to be stressful for calves, as measured by both physiological (Lynch et al., 2010; Kim et al., 2011) and behavioral (Haley et al., 2005) changes. Adopting practices that improve welfare by reducing stress at weaning should be an ongoing pursuit for stakeholders
231 in the beef cattle industry. Accordingly, several methods such as fenceline weaning (Price et al., 2003) and the use of 2-stage weaning using nose flaps (Haley et al., 2005) to prevent suckling while in the presence of the dam were evaluated as strategies to reduce the stress at weaning. Previous experiments have reported that abrupt weaning increases walking distance (Lay et al., 1998; Haley et al., 2005; Enríquez et al., 2010) and decreases the time spent lying relative to weaning strategies where the calf has direct contact with the dam during the weaning process. In the current experiment, the number of steps taken by calves during BLN tended (P = 0.061) to differ, with 2-STG calves taking 2,778 steps/d, AW-T calves taking 2,616 steps/d, and AW-P taking 2,007 steps/d (data not shown). It is not clear why the number of steps would differ before application of treatments. However, the response is likely due to normal individual variation, especially because lying time did not differ (P = 0.20) among treatments during BLN, with an average of 14.4 h spent lying each day (Figure 1). The concentration of BHBA was greater during BLN for AW-T (P = 0.010) than for 2-STG and AW-P, which did not differ (Table 1). Baseline insulin and NEFA did not differ between treatments with P = 0.93 and 0.55, respectively. Upon initiation of the WN period, AW-P calves took twice as many steps on d 2 of WN than AW-T and 2-STG calves (P < 0.001; Figure 1) and spent less time lying (P < 0.001) on d 1 and 2 of WN compared with the other treatment groups, which did not differ. This suggests that despite both 2-STG and AW-P calves losing access to milk on the same day, it was the separation from the dam that caused the AW-P calves to alter their behavior. This is supported by the lack of difference in time spent lying and number of steps taken between 2-STG and nonweaned calves (AW-T) during WN. It appears that implementing the 2-STG weaning system allows calves to express similar behaviors as
232 nonweaned calves, with the exception of suckling. Interestingly, pretransport serum NEFA was greater for 2-STG than AW-T (P = 0.017; Table 1), which suggests that 2-STG calves may spend more time attempting to suckle rather than eating, leading to negative energy balance and mobilization of body fat. However, serum BHBA, plasma glucose, and insulin did not differ between treatments (P > 0.1). Although acute-phase proteins such as serum amyloid A were reported to be elevated after weaning (Kim et al., 2011), we were unable to detect a treatment difference for the concentrations of serum amyloid A and lipopolysaccharide binding protein (P > 0.1) after weaning (BTRANS and ATRANS). This suggests that at the physiological level, all 3 treatments were affected equally by the stresses of weaning. There were no behavioral differences detected between any of the treatments from d 3 of WN onward, which is consistent with the findings of Lambertz et al. (2014), and suggests that the positive
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effect of 2-stage weaning is short in duration. These results support that abrupt weaning is more stressful for calves than weaning in 2 stages but suggest that weaning with the use of nose flaps is not stress free. Likely, the benefit of 2-stage weaning is due to dividing the stress into 2 smaller stressors, namely the loss of milk followed by loss of the dam (Weary et al., 2008). The transportation event in this experiment imposed a physiological stressor as indicated by BW loss (shrink) ranging between 8.9 and 9.4 kg/4 h without differences among treatments (Table 2). Past experiments have indicated that transportation following weaning increased the concentrations of acute-phase proteins such as serum amyloid A and haptoglobin (Arthington et al., 2003). Moreover, plasma glucose is expected to increase after fasting coupled with transportation (Phillips et al., 1991). We did not see differences for BHBA, NEFA, insulin, serum amyloid A, or lipopolysaccharide binding protein.
There was, however, a tendency for blood glucose concentration to be less for 2-STG calves than the other 2 treatments (P = 0.054; Table 1) after transportation. It should be noted that the transportation event was only 4.5 h in duration and calves were not fasted before transportation, which may explain the differential response for the current experiment and a previous experiment (Arthington et al., 2003). There were no differences (P > 0.1) among treatments for plasma or serum metabolites and insulin during REC1 or REC2; however, it should be noted that calves were resorted, but were not mixed with new cohorts, and therefore the stress experienced may not have been severe enough to induce marked changes in metabolism and inflammatory responses. Dry matter intake during REC1 was influenced by day (P < 0.001), with DMI decreasing from d 1 to 2, but then increasing from d 3 to reach a maximum of 7.9 kg on d 5 (Figure 2). There was a tendency for
Figure 1. Effect of weaning method and timing of weaning on the number of steps and lying behavior of steer calves. Calves were exposed to 1 of 3 treatments: (1) abruptly weaned on d 1 (AW-P; black bars) of the period designated weaning (WN), (2) weaned by preventing suckling on d 1 of WN using nose flaps (2-STG; gray bars), or (3) abruptly weaned (AW-T; white bars) on d 1 of receiving. Bars with diagonal lines in panels A and D indicate the overall effect of day as the treatment and treatment × period interactions were not significant during baseline (BLN) measurements. Panels B and E report results during WN, and panels C and F report results during recovery period 1 (REC1). Columns with different letters within a panel indicate values that differ (P < 0.05). Error bars depict the SEM.
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DMI to differ between treatments by day (P = 0.068). Dry matter intake of 2-STG calves followed the same pattern as the day effect, whereas DMI of AW-T calves was least on d 1 and 2 before increasing to d 4 and AW-P calves showed only subtle increases in DMI from d 1 to 5. There were no differences found in REC2 (data not shown), with DMI ranging between 7.2 and 7.8 kg/d. Thus, our data are only partially supportive of past experiments reporting a reduc-
tion in time spent at the bunk for abruptly weaned calves relative to 2-STG calves in response to weaning (Haley et al., 2005). We were unable to detect differences (P > 0.10) for ADG during REC1 or REC2 (Table 2), suggesting that performance is not affected by weaning method. Unfortunately, by using pen as the experimental unit, the power of this portion of the experiment was limited. Therefore, although results suggest that DMI and ADG during the receiv-
ing period are not affected by weaning method, caution must be taken with these findings. In contrast, the timing of the weaning event had an effect on the behavioral responses of calves during a simulated receiving period. On d 1 and 2 of REC1, AW-T calves took more steps than AW-P and 2-STG calves (P < 0.001) and spent less time lying on d 1 of REC1 than both 2-STG and AW-P calves (P < 0.001). On d 2, AW-T calves spent less time
Table 1. Effect of weaning method and timing of weaning on blood metabolites, insulin, and acute-phase proteins in steer calves Treatment2 Variable1
AW-P
2-STG
AW-T
N BLN BHBA, mg/dL Insulin, μg/L NEFA, μEq/mL BTRANS BHBA, mg/dL Glucose, mg/dL Insulin, μg/L NEFA, μEq/mL Serum amyloid A, mg/mL Lipopolysaccharide binding protein, mg/mL ATRANS BHBA, mg/dL Glucose, mg/dL Insulin, μg/L NEFA, μEq/mL Serum amyloid A, mg/mL Lipopolysaccharide binding protein, mg/mL REC1 BHBA, mg/dL Glucose, mg/dL Insulin, μg/L NEFA, μEq/mL REC2 BHBA, mg/dL Glucose, mg/dL Insulin, μg/L NEFA, μEq/mL
9 13.2b 0.19 273 11.3 72.6 0.17 414ab 63 7.5 9.8 83 0.17 504 58 7.6 12.3 80.6 0.13 157 10.6 79.6 0.14 228
10 13.8b 0.22 232 12.7 76.7 0.12 526a 128 9.1 10.6 72.2 0.12 583 148 9.9 12.2 78.7 0.12 165 11.0 76.8 0.20 266
10 17.6a 0.23 252 11.8 82.0 0.15 229b 107 12.4 11.2 82.6 0.16 419 132 13.1 14.2 81.7 0.21 190 12.2 81.7 0.21 190
SEM3
1.0 0.06 27 0.9 3.8 0.03 71 36 2.5 1.3 3.6 0.03 68 43 2.6 1.0 3.8 0.04 33 1.0 4.6 0.04 37
P-value
0.006 0.91 0.58 0.56 0.23 0.34 0.016 0.46 0.36 0.74 0.064 0.30 0.21 0.30 0.34 0.27 0.84 0.22 0.77 0.45 0.74 0.50 0.36
Means within a row with different superscripts differ from each other (P < 0.05). The experiment consisted of 4 measurement periods: baseline (BLN, d −10 to −6 relative to transport), weaning (WN, d −5 to −1 relative to transport), transportation (on the day of weaning, steers were loaded on a trailer and transported for 4.5 h), and a simulated 2-wk receiving period (REC1 and REC2). Blood samples and BW were collected before transportation (BTRANS) and upon arrival after transportation (ATRANS). 2 Calves were exposed to 1 of 3 treatments: (1) abruptly weaned on d 1 (AW-P) of the period designated weaning (WN), (2) weaned by preventing suckling on d 1 of WN using nose flaps (2-STG), or (3) abruptly weaned (AW-T) on d 1 of receiving. 3 The largest SEM is reported. a,b 1
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lying than the AW-P calves (13.3 vs. 16.7 h) but did not differ from 2-STG (15.2 h), which in turn did not differ from AW-P calves. Therefore, calves weaned and transported on the same day appear to exhibit more behavioral indications of stress than those weaned before transport. This finding suggests that part of the diminished stress response observed for 2-STG weaning relative to abrupt weaning in previous experiments (Haley et al., 2005; Enríquez et al., 2011) may in fact be related to the timing of the weaning event. In the current experiment there were no differences in the number of steps taken by calves from d 3 of REC 1 onward, with less than 2,000 steps/d across treatments (Figure 1). Time spent lying did not differ among treatments from d 2 onward, with all calves spending approximately 15.0 h/d lying (Figure 1), supporting previous results that the stress due to weaning appears to be transient, regardless of method of weaning.
Figure 2. Effect of day within recovery period 1 (REC1) and recovery period 2 (REC2) on DMI after calves were (1) abruptly weaned and separated from their dam 5 d prior (AW-P) to the start of REC1, (2) weaned 5 d prior by preventing suckling using nose flaps (2-STG), or (3) abruptly weaned (AW-T) on d 1 of REC1. For REC1 (panel A), P-values for treatment, day, and the treatment × day interaction were 0.96, <0.001, and 0.068, respectively. For REC2 (panel B), P-values for treatment, day, and the treatment × day interaction were 0.96, 0.10, and 0.92, respectively. Means with different letters within a panel indicate values that differ (P < 0.05). Error bars depict the SEM.
The results of the present experiment indicated that regardless of the weaning method used, weaning calves before transportation minimizes behavioral indicators of stress in a simulated receiving period but does
Table 2. Effect of weaning method and timing of weaning on BW and ADG of steers Treatment2 Variable1
AW-P
2-STG
AW-T
SEM3
P-value
BLN, kg BTRANS, kg ATRANS, kg Shrink,4 kg REC1 BW, kg ADG, kg/d REC2 BW, kg ADG, kg/d
236 233 225 8.98 245 2.92 248 0.51
234 244 235 9.43 254 2.75 255 0.19
235 234 231 9.03 248 2.41 255 0.99
6 7 7 1.72 8 0.39 8 0.37
0.99 0.57 0.57 0.98 0.71 0.65 0.80 0.32
The experiment consisted of 4 measurement periods: baseline (BLN, d −10 to −6 relative to transport), weaning (WN, d −5 to −1 relative to transport), transportation (TRANS; on the day of weaning steers were loaded on a trailer and transported for 4.5 h), and a simulated 2-wk receiving period (REC1 and REC2). Blood samples and BW were collected before transportation (BTRANS) and upon arrival after transportation (ATRANS). 2 Calves were exposed to 1 of 3 treatments: (1) abruptly weaned on d 1 (AW-P) of the period designated weaning (WN), (2) weaned by preventing suckling on d 1 of WN using nose flaps (2-STG), or (3) abruptly weaned (AW-T) on d 1 of receiving. 3 The largest SEM is reported. 4 The difference between BTRANS and ATRANS BW. 1
not improve DMI or ADG. Additionally, the use of a 2-stage weaning approach mitigated behavioral changes in response to the weaning process.
IMPLICATIONS The results of this experiment support previous studies indicating that use of a 2-stage weaning approach reduces behavioral indicators of stress associated with weaning in calves. These findings further suggest that part of the benefit observed with 2-stage weaning may be attributable to calves being weaned before transport. Furthermore, weaning calves before transportation, regardless of method, can be effective in reducing behavioral indicators of stress upon arrival at the feedlot but may not affect performance.
ACKNOWLEDGMENTS Funding for the project was provided through the Natural Sciences and Engineering Research Council of Canada (NSERC) ENGAGE program and JDA Livestock Solutions Inc. (Saskatoon, SK, Canada). The authors would like to thank R. Kanafany Guzman, P. Górka, G. Gratton, and M. E. Walpole at the University of Saskatchewan for assistance with
Method and timing of weaning
data and sample collection and analysis, and F. Brown and C. Goldhawk at Agriculture and Agri-Food Canada for assistance with the pedometer measurements.
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