Comparison of alternative backgrounding systems on beef calf performance, feedlot finishing performance, carcass traits, and system cost of gain1

The Professional Animal Scientist 28 (2012):541–551

©2012 American Registry of Professional Animal Scientists

Comparison of alternative backgrounding systems on

beef calf performance, feedlot finishing performance, carcass traits, and system cost of gain1 R. Kumar,* H. A. Lardner,*†2 J. J. McKinnon,* D. A. Christensen,* D. Damiran,*† and K. Larson† *Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5A8 Canada; and †Western Beef Development Centre, Humboldt, Saskatchewan S0K 2A0, Canada

ABSTRACT A 3-yr experiment was conducted to evaluate the effects of swath grazing forage barley (Hordeum vulgare; cv. Ranger) or foxtail millet (Setaria italica; cv. Golden German) compared with grass-legume hay fed in drylot pens on beef calf performance during backgrounding and finishing phases. Annually, 120 spring-born Angus-cross stocker calves (60 steers, 60 heifers; BW = 227.6 ± 3.5 kg) were randomly allocated to 1 of 3 replicated (n = 2) backgrounding (BG) systems. Backgrounding systems were 1) swathed barley grazing (BAR), 2) swathed millet grazing (MILL), and 3) 1 This research was supported in part by grants from the Saskatchewan Agriculture Development Fund (Regina, SK), Saskatchewan Cattle Marketing Deduction Fund (Regina, SK), Advancing Canadian Agriculture and Agri-Food Fund (Ottawa, ON), and Western Beef Development Centre (Humboldt, SK). 2 Corresponding author: blardner.wbdc@ pami.ca

ground hay bunk fed in drylot (DL). All calves were supplemented with a 16% CP range pellet (2.5 kg/d). Swath-grazed calves were limit grazed using electric fencing in 4-ha paddocks with a 3-d grazing period for 96 d each year. Following BG, calves were placed in a feedlot, separated by BG treatment, and fed a similar finishing diet for 155 d and harvested at a targeted endpoint of 12 mm of rib fat. Forage samples were collected every 21 d and analyzed for DM, CP, and DE. Digestible energy content was greatest (P < 0.05) for swathed barley (10.0 MJ/ kg) and lowest for DL hay (8.4 MJ/kg). Stocker ADG during BG was greatest (P < 0.05) for BAR (0.8 kg/d) compared with MILL (0.6 kg/d), and DMI of BAR calves (7.8 kg/d) was numerically greater (P = 0.32) than MILL (6.8 kg/d) or DL calves (7.5 kg/d). Cost of gain for the BAR system ($1.70/kg) was 31% less (P < 0.05) compared with the MILL ($2.45/kg) or DL ($2.47/kg) system, suggesting swath grazing whole plant barley with beef calves may be more cost effective. There were no differences (P > 0.05) in final feedlot BW, total feedlot

ADG, rib or rump fat, carcass characteristics, or feedlot cost of gain of calves from the 3 backgrounding systems. This experiment indicates that backgrounding calves on swathed barley or millet in field paddocks will not adversely affect feedlot performance or carcass characteristics compared with backgrounding calves in a traditional DL system. Key words: backgrounding, barley beef calf, feedlot finishing, millet, swath grazing

INTRODUCTION Backgrounding is the controlled rate of growth of beef animals to maximize frame size before the deposition of fat to obtain a greater carcass weight at slaughter (Perillat et al., 2003). Muscle development and skeletal size are related to carcass weight and the potential growth during the backgrounding period (Tatum et al., 1988). Traditionally in western Canada, spring-born calves are grazed on pasture with their dams during sum-

542 mer, weaned in the fall and moved to pens for backgrounding, where they are fed stored feedstuffs, a traditional drylot feeding system (Karantininis et al., 1997). This phase is then followed by feedlot finishing where calves are fed to a targeted harvest weight. In Saskatchewan, Canada, the cow-calf operation is the main enterprise for many beef cattle producers; however, high inputs and yardage costs involved in pen feeding can affect profit (Saskatchewan Ministry of Agriculture, 1998). Growth of the Saskatchewan beef industry depends on developing alternate backgrounding programs for beef calves and evaluating which program is economically feasible (Gould and Price, 1998). Based on cost of gain, feed availability, and current markets, producers will ascertain whether calves should be backgrounded on swath-grazed annual forages or fed processed forage in the feedlot. Cattle entering the feedlot will differ in age and weight as a result of different backgrounding systems, which could produce differences in carcass quality (Klopfenstein et al., 2000). For efficient backgrounding, proper selection of forage species should be based on agro-climatic growing conditions and the forage should provide adequate quality and nutrient density for desired growth of the animal. Swath-grazed cereals are well suited to provide quality feed due to flexible seeding dates and high yield compared with cool season perennials, which can lead to better animal performance in backgrounding systems (McCartney et al., 2008). Aasen et al. (2004) indicated that swath grazing, can reduce cost of baling, hauling, feeding, and manure removal. Studies evaluating alternative backgrounding systems on beef calf performance and cost of gain through to harvest are limited. Therefore, the objective of this experiment was to compare the effects of 3 backgrounding systems: swathed barley grazing, swathed millet grazing, and drylot pen feeding on beef calf performance, subsequent feedlot performance, carcass characteristics, and system cost of gain.

Kumar et al.

MATERIALS AND METHODS Experimental Sites and Crop Management Backgrounding trials over 3 yr were conducted at the Western Beef Development Centre’s Termuende Research Ranch located near Lanigan, Saskatchewan, Canada (51°51′N, 105°02′W). The Termuende Research Ranch is located in east-central Saskatchewan, and soils consist primarily of a mixture of Oxbow Orthic Black and carbonated Oxbow with a loam texture (Saskatchewan Soil Survey, 1992). In spring of each year (June 12, 2007, May 29, 2008, and June 10, 2009), 8 ha of forage barley (Hordeum vulgare; cv. Ranger) and 8 ha of foxtail millet (Setaria italica; cv. Golden German) were seeded at 109 and 17 kg/ha, respectively. Both crops also received actual N fertilizer applied at 22.7 kg/ha. In the fall, before grazing, each field of barley or foxtail millet was further sub-divided into replicate (n = 2) 4-ha paddocks for swath grazing systems using portable electric fencing. The same 16-ha field was used in all 3 yr.

Grazing Animal Management Over 3 yr, backgrounding trials were conducted from October 19, 2007, to January 24, 2008 (yr 1); October 15, 2008, to January 15, 2009 (yr 2); and November 9, 2009, to February 2, 2010 (yr 3). Each year, 120 springborn Black Angus calves (BW = 227.6 ± 3.5 kg; 60 steers; 60 heifers) were used for the experiment. Calves were weaned (in late September of each year) and adapted for 15 d to field crop treatments before their allocation to the different backgrounding systems. All animals were cared for in accordance with the guidelines of the Canadian Council on Animal Care (1993). Before starting each trial, all calves were vaccinated against bovine respiratory syncytial virus, infectious bovine rhinotracheitis, bovine viral diarrhea, and parainfluenza 3 (STARVAC 4 plus; Novartis Animal Health Inc., Mississauga, Ontario, Canada),

and a Clostridium 8-way modified live vaccine (Covexin 8; Schering-Plough Animal Health, Guelph, Ontario, Canada). Calves were also dewormed with 30 mL of ivermectin (Megamectin, Novartis Animal Health Inc.) topically and implanted with 36 mg zeranol (Ralgro, Schering-Plough Corp., Kenilworth, NJ). Calves were stratified according to BW and gender and randomly allocated to 1 of the 3 backgrounding systems. Each backgrounding system (n = 3) had 2 replicates (n = 2; 2 paddocks and pens for grazing and feeding system, respectively), and each replicate group consisted of 20 calves (10 steers; 10 heifers). The drylot pen system was located at the Termuende Research Ranch, 0.5 km away from the winter field grazing site. Two drylot pens surrounded by wooden slatted fences with 20% porosity fencing were used with a stocking density of 20 calves per pen.

Backgrounding Systems Calves were allocated feed in each backgrounding system based on BW, forage nutrient density from laboratory analysis, and environmental conditions using CowBytes Beef Ration Balancing Program (Version 4, Alberta Agriculture, Food and Rural Development, Alberta, Canada) according to NRC (2000) requirements for growing beef calves with a targeted BW gain of 0.8 kg/d. Backgrounding systems included 1) barley swath grazing (BAR), where the barley was swathed at soft dough stage into windrows and beef calves grazed windrowed feed in field paddocks; 2) millet swath grazing (MILL) where the millet was swathed at 30% heading into windrows and beef calves grazed windrowed feed in field paddocks; and drylot (DL) pen feeding, where beef calves were housed in outdoor pens (50 × 120 m) and bunk fed a similar ration of processed (coarsely chopped) grass-legume (80% brome; 20% alfalfa) hay. Grass-legume hay is the most commonly used forage for backgrounding beef calves in western Canada.

Alternative backgrounding systems for beef calves

In the field grazing systems (BAR, MILL), the outer perimeter of each paddock was fenced with high tensile electric wire, and feed was allocated every 3 d by moving the fence. All calves were supplemented daily at 0800 h with a range pellet (16% CP; 10.5% ADF; 77.0% TDN; 15.2 Mcal/ kg DE; 33 mg/kg monensin sodium (Rumensin 200; Elanco Animal Health, Guelph, Ontario, Canada) at 2.5 kg/d to meet protein and energy requirements during the backgrounding phase. All calves had ad libitum access to a commercial 2:1 mineral supplement (Feed-Rite Mineral Ltd., Winnipeg, Manitoba, Canada) that contained 22% Ca, 14% P, and 1% Zn (guaranteed minimum of 125 mg/ kg I, 4,000 mg/kg Cu, 5,300 mg/kg Mg, 40 mg/kg Co, 450 mg/kg Fe, 200 KIU/kg of vitamin A, and 40 IU/ kg of vitamin E) and cobalt iodized salt that contained 99% NaCl (guaranteed minimum of 150 mg/kg I, and 100 mg/ kg of Co) throughout the backgrounding period. Three portable wind breaks (10 m × 6 m) and a water trough were provided in each paddock.

Calculations Estimated average DMI of BAR or MILL backgrounding systems was

determined as a percentage of forage DM disappearance between preand postgrazed sampling of swaths and bales in each paddock and pen, similar to the technique described by Volesky et al. (2002) and Kelln et al. (2011). Each year, immediately after swathing, but before grazing, DM yield per linear meter of swathed forage was determined by weighing 25 (3 × 1 m) random sections of swath in each paddock. Determining DM of residual feed per meter was estimated using the same technique, and before weighing of residual feed, all fecal, and foreign debris not associated with the residue was removed. Average daily forage DMI was calculated using the following equation: DMI, kg/d = (kg DM/p allocated – kg DM/p residual)/n/p; where p = 3-d feeding period; n = 20 calves per experimental unit. For the DL system, calves were fed for ad libitum intake with feed delivered once daily at 0800 h with a mixer wagon, and the amount of feed delivered to each pen was recorded daily. Every 2 wk, the bunks were cleaned and any orts were weighed. Actual DMI was calculated based on DM delivered to the pen and corrected for any orts that were recorded.

Table 1. Effect of backgrounding system on estimated DMI, consumed nutrients, and beef calf performance over 3 yr Backgrounding system1 Item

BAR

MILL

DL

SEM

P-value

DMI, kg/d CP, kg/d NDF, kg/d TDN, kg/d DE, MJ/d Performance2   Initial BW, kg   Final BW, kg   ADG, kg/d   BW change, kg

7.76 0.92 3.25 4.28 76.31   207.1 288.1a 0.8a 77.9a

6.81 0.90 3.16 3.51 61.25   207.3 269.4b 0.6b 59.0b

7.53 0.75 3.84 3.89 68.65   207.7 290.7a 0.8a 79.9a

0.447 0.105 0.286 0.518 8.116   8.46 7.65 0.03 4.39

0.32 0.19 0.23 0.27 0.13   0.99 0.01 <0.01 <0.01

Means within a row with different superscripts differ (P < 0.05). 1 BAR = swathed barley grazing; MILL = swathed millet grazing; DL = drylot pen feeding. 2 4% pencil shrink applied to all BW. a,b

543

Forage Analysis Composite samples from barley swaths, millet swaths, and ground hay from each pen of the DL system were collected before the start of trial and every 21 d throughout the trial. All samples were placed in a forced-air oven at 55°C for 72 h to obtain DM content. Samples were then ground to pass through a 1-mm screen using a Wiley mill (model 2, Arthur H. Thomas Co., Philadelphia, PA). Duplicate samples were then analyzed for total DM, ether extract, ADF, and ADL according to the AOAC (2000). Neutral detergent fiber was analyzed according to the procedure of Van Soest et al. (1991). Neutral detergent fiber and ADF were analyzed using an Ankom 2000 Fiber Analyzer (Ankom Technology, Fairport, NY). Crude protein was determined by the Kjeldahl nitrogen method (AOAC, 2000) using a Kjeltec 2400 auto analyzer. The Kjeltec 2400 auto analyzer was also used to determine ADF and NDF insoluble protein (AOAC, 2000) with residues recovered on Whatman No. 54 paper. Feed TDN and DE levels were determined according to Weiss et al. (1992). Estimated diet quality (DQ; CP, NDF, ADF, TDN, and DE) was calculated as DQ(% DM) = [∑Ii(DQi/100)/∑Ii]100, where Ii is the DMI of each diet (forage and supplement) during the backgrounding trial (kg/d), and DQi = nutrient composition of each feed i (% DM; Table 1).

Animal Measurement All BW were measured unshrunk at similar time of day, and a 4% pencil shrink was applied. Body weights were taken on 2 consecutive days at the start and end of the trial and every 21 d throughout the trial.

Weather Temperature and precipitation data during the experiment were collected from a Termuende Research Ranch Benchmark Site weather station located 1.5 km east of the experimental site. Precipitation in the form

544 of snow was obtained from Environment Canada’s Climate Data for Esk, Saskatchewan, approximately 5 km southeast of the experimental site (51°48′N, 104°51′W; http://www. climate.weatheroffice.ec.gc.ca). The 3-yr average monthly precipitation at the experimental site for May, June, July, and August was 27.7, 66.3, 65.2, and 51.7 mm, respectively. The 30-yr average precipitation for the Lanigan area was 53.5, 83.9, 66.1, and 53.0 mm for May, June, July, and August, respectively. Three-year average monthly temperature at the experimental site for May, June, July, and August was 9.64, 14.72, 19.37, and 17.51°C, respectively. The 30-yr average temperature for the Lanigan area was 11.3, 15.91, 18.12, and 17.20°C for May, June, July, and August, respectively. Klein (2008) reported that the optimum growing temperature in Saskatchewan for a cool season crop such as barley is 18 to 24°C, and for warm season crops such as millet, the optimum temperature is 32 to 35°C. This may suggest that the average growing season temperature in the Lanigan area may favor optimum growth of barley, rather than millet. The 3-yr average temperature at the experimental site for October, November, December, and January was 4.78, −2.83, −17.34, and −15.95°C, respectively. During December, the temperature was 3.4°C lower, but otherwise normal temperatures were observed compared with the 30-yr average, during the grazing trial period. The 3-yr average monthly precipitation at the experimental site for October, November, December, and January was 29.15, 31.75, 14.00, and 2.87 mm, respectively. This indicates that November and January precipitation (in the form of snow) was 2.4 (13 mm higher) and 1.5 times (9.4 mm higher) greater than the 30-yr average, respectively.

Finishing Trial Animal Management. Following the grazing/backgrounding phase, all calves were group fed grass-legume hay (7 kg/per calf daily; 86% DM; 11.2% CP; 53.3% NDF; 34.6% ADF)

Kumar et al.

and 2.5 kg/d supplement pellet in drylot pens for 20 to 30 d during transition period before entering the feedlot. Calves were then shipped 115 km to the University of Saskatchewan Beef Research Unit located in Saskatoon, Saskatchewan, for the finishing trial. Upon arrival at the feedlot, all calves were vaccinated against Clostridial diseases (Covexin 8; Schering-Plough Animal Health, Kirkland, Quebec, Canada), Pasteurella hemolytica and Histophilus somni (Somnu-Star Ph; Novartis Animal Health Inc.), infectious bovine rhinotracheitis, bovine viral diarrhea (type 1 and 2), parainfluenza type 3 virus and bovine respiratory syncytial virus (Biostar, Starvac 4 Plus, Novartis Animal Health Inc.). Calves were further implanted with a trenbolone acetate (200 mg)-estradiol (20 mg) combination implant (Synovex Choice; Wyeth Animal Health, Guelph, Ontario, Canada). All calves were sorted by sex and backgrounding treatment and randomly assigned to 1 of 12 pens with a stocking density of 10 animals (steers or heifers) per pen. Finishing Feeding Management. Calves were adapted to the finishing diet through a series of 8 ration changes, which included a gradual diet increase in barley grain through replacement of barley straw and grass hay. A similar diet was fed to calves at different phases of the step-up program with the final finishing diet consisting of 87.1% barley grain, 5.3% supplement, and 7.7% barley silage (DM basis), which was formulated to provide 7.74 and 5.06 MJ/kg NEm and NEg, respectively, and which was considered sufficient for a targeted gain of 1.6 kg/d (Zinn et al., 2002). Diets were also formulated to meet NRC (2000) requirements with a Ca:P ratio of 1.5:1 to 2:1 and contained 27 mg/kg of monensin sodium (Rumensin, Elanco Animal Health). Calves were fed twice daily at 0800 and 1400 h. Feedlot DMI was calculated by a similar procedure as described previously in the DL treatment of the backgrounding trial. Samples from individual ingredient and total ration were collected every 2 wk and stored

for further chemical analysis. All samples were analyzed by techniques previously described for the backgrounding trial. Animal Measurement. All BW, subcutaneous fat (rib fat, mm) depth, and longissimius dorsi fat (rump fat, mm) reserves were used as indicators of animal performance. At start and end of the feedlot phase, calf BW were taken on 2 consecutive days before the morning feeding and every 28 d throughout the trial. Rib and rump fat of the live animal were measured every 2 wk with ultrasound as described by Bergen et al. (1997) using an Aloka SSD-500V real-time ultrasound machine and Aloka UST-5044 probe (3.5 MHz, Aloka Inc., Wallingford, CT). Carcass Measurement. In the first 2 yr of the experiment, animals were slaughtered at a commercial facility approximately 225 km from the feedlot, after reaching 12 mm rib fat. The animals were shipped the day before harvest and held overnight in lairage. Hot carcass weight was obtained immediately after harvest. After 24 h, carcasses were knife ribbed between the 12th and 13th rib, and carcass data (dressing percentage, yield grade, longissimius dorsi area size, and marbling score based on a 10-point system [score: 1 (very abundant), 5 (moderate), 10 (devoid)]. Shrunk ship weight, HCW, dressing percentage, yield grade, longissimius dorsi area, and marbling score were collected by Canadian Beef Grading Agency graders. Backgrounding Systems and Finishing Costs. The economic comparison of different backgrounding systems was analyzed using similar procedures as described in detail by Jungnitsch (2008) and Kelln et al. (2011). System costing tracks the costs associated with labor, machinery, yardage, and feed for each backgrounding treatment. Swath grazing feed costs included the actual costs for inputs—seed, fertilizer, herbicide—used to produce the barley and millet swaths. For the DL backgrounding system, feed costs were based on purchase price for hay used

Alternative backgrounding systems for beef calves

in diet, as well as the costs to process and supply the feed. The feedlot finishing trial included feed ingredient costs and yardage. Equipment costs in the backgrounding systems were calculated by multiplying custom rates published in the Saskatchewan Ministry of Agriculture’s Farm Machinery Custom and Rental Rate Guide (SMA, 2008–2009) by the time spent using the equipment. Total time spent feeding was calculated by averaging the time spent on the entire feeding process during 2 consecutive days. Time spent using equipment was measured after observing the various activities during the feeding process. Cost of labor was estimated at $15/h, and the rate for manure removal was estimated at $0.04/calf daily. Total production costs ($/calf daily) associated with each system were divided into 3 subgroups: 1) feed, 2) other direct costs (i.e., bedding, treatment costs), and 3) yardage. Feed costs included the expenses associated with production or purchase of forage, supplementation, and mineral/salt fed to the animals. Total cost of the feed or ration was determined by production cost for feedstuffs grown on-site or purchase cost per kilogram of feed produced multiplied by the amount (kg) consumed. Yardage cost included the machinery (equipment) used, labor for the different systems, repairs of building and corrals, depreciation, and manure removal (DL only). The cost of gain (COG, $/kg) for each system was calculated by dividing total production costs ($/calf daily) by animal gain (kg/d). Statistical Analysis. Statistical analysis of calf data was conducted using the Proc Mixed model procedure of SAS (SAS Institute Inc., Cary, NC). The experimental model was Yab = µ + ρa + αb + eab, where a is the block (year), b is the background system, µ is the overall mean, ρa is the random effect of the ith year, αb is the fixed effect of the jth treatment, and eab is the error term. Performance data including ADG, BW, DMI, and DE intake were analyzed using a randomized complete block design (RCBD) with year

as a block. Backgrounding systems (BAR, MILL, and DL) were included as main treatments with 6 replicates per treatment over 3 yr. For forage nutritive analysis, the model included fixed effect of forage (backgrounding system), sampling time (time), and forage × time with year as a blocking factor. Analysis showed that the effect of forage was significant; however, time and forage × time were not significant (P > 0.05), and hence, time and forage × time interaction were removed from the model and data were re-analyzed to assess only the main effect of forage. Each replicate group of calves (n = 20) was considered an experimental unit for a total of 18 experimental units over the 3-yr experiment. For the feedlot trial, animal performance data were also analyzed as an RCBD with pen as an experimental unit. The model included fixed effect of backgrounding system, with year as a blocking factor. Similarly, carcass and system COG data were analyzed using an RCBD. Marbling score data were analyzed using the GLIMMIX macro (SAS Institute Inc.) with a binomial error structure and logit data transformation. For all data, Tukey’s multiple range test was applied to determine whether the treatment means were different, and differences were considered significant when P < 0.05.

RESULTS AND DISCUSSION Forage Yield and Nutritive Value Swathed barley biomass was greater (P < 0.05) than swathed millet biomass (5,952 vs. 3,467 kg/ha; SEM = 362 kg/ha) over the 3-yr experiment (Figure 1). Whole plant barley swath had the lowest (P < 0.05) NDF and ADF, but was greater (P < 0.05) in TDN and DE than whole plant millet swath or brome-alfalfa hay (Table 2). Whole plant millet swath had greater (P < 0.05) CP concentration among all backgrounding forages; however, millet was similar (P > 0.05) in NDF and energy (TDN, DE) concentration to the brome-alfalfa hay fed in the DL

545

Figure 1. Swathed barley and millet crop biomass (DM) over 3 yr. Vertical bars with different letters (a,b) differ (P < 0.05).

system. The brome-alfalfa hay had the greatest (P < 0.05) ADF and the lowest CP level. Crude protein, ADF, NDF, TDN, and DE concentrations in forages in the current experiment were similar to forage quality reported by other grazing studies (Mackay et al., 2003; McCartney et al., 2004; Baron et al., 2006; Kelln et al., 2011). Estimated dietary composition of BAR backgrounding system was lower (P < 0.05) in NDF and ADF, but greater (P < 0.05) in TDN and DE compared with ration composition of MILL or DL systems (Table 2). Additionally, ADF level was the greatest (P < 0.05) in the DL system diet, but lower (P < 0.05) in CP. Estimated dietary TDN tended (P = 0.06) to be greater in the BAR backgrounding system than in the MILL and DL backgrounding systems. Overall, estimated diet composition in all backgrounding systems met NRC (2000) recommended CP density for backgrounding this class of cattle.

Average DMI and Nutrient Intake No differences (P > 0.05) were detected among backgrounding systems for average DMI or nutrient intake by the calves (Table 3). Estimated daily DMI were 7.76, 6.81, and 7.53 kg/d for BAR, MILL, and DL systems, respectively. According to NRC (2000) level 1 model, based on a diet containing 60% TDN, calves with a

546

Kumar et al.

Table 2. Nutrient composition of forages and estimated dietary composition fed in backgrounding systems over 3 yr (DM basis) Item DM, % CP, % NDF, % ADF, % TDN, % DE, MJ/kg Diet composition1 CP, % NDF, % ADF, % TDN, % DE, MJ/kg

Barley

Millet

Hay

75.2b 60.5c 83.8a 11.8b 13.8a 8.8c b a 64.8 74.3 77.3a 42.1c 48.0b 54.4a 62.7a 57.3b 55.7b a b 8.8 8.4b 10.0 Backgrounding system2 BAR

MILL

12.4 45.5c 30.7c 56.5 10.5

b

SEM

P-value

0.33 0.38 2.52 1.14 1.31 0.24  

<0.01 <0.01 <0.01 <0.01 <0.01 <0.01  

0.57 1.82 1.02 1.85 0.38

<0.01 <0.01 <0.01 0.06 0.09

DL

13.9 50.2b 33.8b 53.7 10.0 a

10.4c 55.0a 40.1a 52.7 10.0

Means within a row with different superscripts differ (P < 0.05). Forage and supplement. 2 BAR = swathed barley grazing; MILL = swathed millet grazing; DL = drylot pen feeding. a–c 1

Table 3. Effect of backgrounding system on feedlot performance of beef calves over 3 yr Backgrounding system1 Item

BAR

MILL

DL

SEM

P-value

Performance Initial BW, kg Final BW, kg ADG, kg/d ADG2 ADG, d 1 to 28 ADG, d 29 to 56 ADG, d 57 to 84 ADG, d 85 to 112 DMI, kg/d Feed:gain Rib fat,3 mm  Initial  Final  Change Rump fat,4 mm  Initial  Final  Change

  323.8a 602.1 1.63   0.49 0.39 0.46 0.45 11.46 7.02   5.79 12.15 6.30   60.02 90.64 28.50

  307.3b 595.7 1.65   0.49 0.41 0.52 0.42 11.46 6.92   4.99 11.75 6.30   57.63 88.50 28.85

  320.8a 601.3 1.61   0.47 0.42 0.47 0.45 11.40 7.03   5.09 11.55 6.20   60.69 91.60 28.40

  5.85 9.78 0.04   0.04 0.02 0.03 0.03 0.16 0.12   0.79 0.34 0.89   2.02 1.26 2.50

  <0.01 0.74 0.59   0.86 0.44 0.08 0.32 0.88 0.50   0.46 0.39 0.99   0.54 0.22 0.98

Means within a row with different superscripts differ (P < 0.05). BAR = swathed barley grazing; MILL = swathed millet grazing; DL = drylot pen feeding. 2 ADG as percentage of mean BW. 3 Ultrasound measurements of subcutaneous fat thickness. 4 Ultrasound measurements of longissimus dorsi area. a,b

1

similar BW and ADG target as the current experiment were predicted to have DMI in the range of 6.95 to 9.51 kg/d. Stocker calves in the BAR and DL systems had estimated DMI that were within this range, but calves in the MILL system consumed slightly less than the NRC prediction. Several studies (Cordova et al., 1978; Van De Kerckhove et al., 2011) conducted with grazing cattle in the western United States and Canada indicated DMI estimates have generally ranged between 1 to 3% of BW. Similarly, calves in the current experiment consumed 3.1, 2.9, and 3.0% of BW for the BAR, MILL, and DL backgrounding treatments, respectively. Several factors can influence DMI of grazing animals, but the most important factors are forage availability and gastrointestinal fill (Van Soest, 1994). Because swathed forages were allocated, feed accessibility was not expected to limit DMI in the current experiment. Forage NDF is the predictor of rumen fill in grazing ruminants (Van Soest, 1994). In this experiment, daily NDF intake was 1.3, 1.3, and 1.5% of BW for the BAR, MILL, and DL calves, respectively. According to Allen (2000), DMI is negatively correlated with NDF when intake is limited by gut fill and positively correlated when intake is limited by energy. In this experiment, the correlation between available feed NDF and DMI of MILL system stockers was negative and moderate (r = −0.529; P = 0.281; n = 6), which is an indication that millet NDF concentration was not the only factor affecting the lower DMI associated with the whole plant millet in swaths. Another possible reason for the lower DMI of the MILL system compared with the BAR and DL system may be due to millet plant structures such as the presence of bristles in the inflorescence. An observation following swathing and drying in the field was that the whole plant millet seed heads became very hard, possibly reducing the palatability of the forage. Another observation was the increased moisture (lower DM; Table 2) content of the swathed millet in

Alternative backgrounding systems for beef calves

November and December in all 3 yr, when some plants were frozen, potentially affecting apprehension and DMI of the forage. This may also have reduced palatability (Damiran, 2005) of the swathed millet crop, ultimately leading to reduced DMI of calves on this backgrounding system. Estimated DMI of BAR and DL calves was similar (7.8 vs. 7.5 kg/d), yet estimated DE intake was 10% greater for BAR calves compared with DL calves. McCartney et al. (2004) reported that beef cows grazing swathed barley had similar levels of DMI (10.7 vs. 11.7 kg/d) compared with silage-fed cows, but swath-grazing cows gained weight more slowly (P < 0.01) compared with silage-fed drylot system cows. The differences observed by McCartney et al. (2004) compared with the results of the current experiment suggest that the maintenance energy (NEm) requirements of calves grazing swathed barley were higher due to exposure to environment in extensive paddocks compared with DL calves in pens. Likewise, Kelln et al. (2011) reported similar DMI (12.3 and 13.4 kg/d) for beef cows swath grazing barley and managed in drylot pens in a 3-yr winter grazing experiment conducted in Saskatchewan, and Volesky et al. (2002) observed similar DMI of windrow-grazing calves and bale-fed calves in Nebraska. Based on the combination of DMI and forage energy density, the calculated DE intake tended (P = 0.13) to be higher for the BAR calves (76.3 MJ/d), lowest for the MILL calves (61.3 MJ/d), and moderate for the DL calves (68.7 MJ/d; Table 3). As stated by NRC (1996), maintenance energy requirements increase by 10 to 20% for grazing animals compared with cattle managed in a drylot pen. If this additional energy increase is compared between calves in the current experiment, the stockers in MILL system consumed 10 to 20% less energy compared with their counterparts fed in DL or BAR systems.

Animal Performance There were no differences (P > 0.05) for initial BW among the back-

grounding systems (Table 1). Calves in the BAR and DL systems had similar (P > 0.05) final BW (288.1 vs. 290.7 kg), which were greater (P < 0.05) than the final BW (269.4 kg) of MILL calves. On average, calves in the MILL system gained 25% less than calves in the DL or BAR system (59.0 vs. 78.9 kg; SEM = 4.39). This difference is likely attributed to calves in BAR system consuming a similar calculated energy intake as DL calves, whereas it was estimated that calves in MILL system consumed 10 to 20% lower energy (Table 1). Calves attained the targeted ADG of 0.8 kg in BAR and DL systems, but ADG for MILL calves was only 0.6 kg. As additional evidence, the correlation between calves ADG and DEI increased when adjusting BAR and MILL calf energy intake by 10 (r2 = 0.61, P = 0.006, n = 18) and 20% (r2 = 0.71, P = 0.001, n = 18) compared with the correlation between ADG and unadjusted energy (r2 = 0.47; P = 0.050, n = 18). Overall, these findings are in agreement with those results of McCartney et al. (2004) and Kelln et al. (2011), which suggested that beef animals managed in extensive grazing systems need additional energy supplementation.

Finishing Performance Initial BW of BAR calves at start of feedlot phase was similar (323.8 vs. 320.8 kg; P < 0.05) to DL calves, and 16.5 kg greater than initial BW of MILL calves (307.3 kg; Table 3). Initial BW for DL calves was 13.5 kg greater (P < 0.05) than the MILL calves. However, no differences were found in final feedlot BW among calves due to backgrounding systems (P = 0.744). On average, the MILL calves gained 10 kg more than BAR calves (288.4 vs. 278.3 kg) and 8 kg more than the DL calves (288.4 vs. 280.4 kg) during the finishing period. Nevertheless, DMI was not (P = 0.882) different among systems with a mean DMI of 11.46 kg/d during the finishing period. No difference was observed in feedlot ADG (P = 0.598) of calves among the systems, although

547

the current experiment revealed a tendency (P = 0.08) for the MILL calves to gain faster from d 57 to 84 of the finishing period compared with the BAR and DL calves, suggesting a compensatory gain by the MILL calves. In agreement to the current experiment, a compensatory gain was reported by Hersom et al. (2004), where differences in backgrounding ADG of calves grazing winter wheat and native range were mitigated during the finishing period where all animals were provided the same finishing ration. White et al. (1987) also reported similar results, where steers grazing winter wheat pasture during the backgrounding period had the highest BW gains and exhibited the highest BW gain during the first 28 d of a subsequent summer grazing period or feedlot finishing period. However, calves were not different (P > 0.05) in rib and rump fat. Variation in results have been well documented on the effects of different backgrounding systems with different nutrient restrictions on the subsequent finishing performance and carcass characteristics due to differences in severity and duration of feed restriction (Klopfenstein et al., 2000; Choat et al., 2003). Carstens et al. (1991) reported that steers limit fed a diet during backgrounding (0.04 kg/d ADG) exhibited a compensatory gain 37% greater than those continuously fed during finishing. Moreover, Choat et al. (2003) also documented that steers grazing native range gained 28% less compared with animals grazing winter wheat over a 180-d background period, but finishing ADG was 7.4% greater for the native range backgrounded steers compared with the winter wheat backgrounded steers. Lack of any significant effect of compensatory gain for the MILL calves during feedlot finishing may be due to length of the winter grazing period and thus a lesser degree of feed restriction was imposed in this experiment. An increased compensatory growth can be exploited when lower growth during one phase of beef production coincides with time of low input and allows the expres-

548 sion of this growth when input costs are high (Drouillard and Kuhl, 1999). There is also the practice of assigning price discounts for feeder cattle, entering the feedlot with greater body condition (Smith et al., 2000). Based on data in the current trial, price discounts of calves grazing swathed barley (BAR), having greater body condition may not be justified in relation to their subsequent finishing performance. Furthermore, any factor affecting forage availability or quality may change the degree of compensation in grazing animals (Lewis et al., 1990). Similar to our results, Hersom et al. (2004) reported that steers grazing either native range (with low ADG) or winter wheat (with high ADG) during backgrounding had similar feedlot performance. In contrast, Phillips et al. (1991) obtained increased gains and improved feed efficiency during finishing for animals previously grazing dormant native grass (with low ADG) compared with steers grazing winter wheat (with high ADG) during the backgrounding period. As noted by Choat et al. (2003), it may be difficult to explain the variation in results of different experiments because of multi-factorial causes, which may include number of days animals grazed, initial body composition, genetics, environment, and performance of animals that were restricted and nonrestricted in nutrient intake.

Carcass Characteristics No differences were observed for shrunk ship weight or HCW among the BAR, MILL, or DL backgrounding systems (P > 0.05; Table 4). Grade fat (P = 0.87), DP (P = 0.54), estimated lean yield (P = 0.64), longissimus dorsi area size (P = 0.26), and marbling score (P = 0.1 to 0.90) were also unaffected by backgrounding treatment. In Nebraska, Lewis et al. (1990) fed steers during finishing with a common dry-rolled corn and corn silage-based ration, and no differences (P > 0.05) were found in HCW, QG, or YG, indicating no effect of winter gain (backgrounding) on carcass characteristics of the

Kumar et al.

steers. Likewise, Hersom et al. (2004) reported no differences in dressing percentage, rib-fat thickness, kidney, pelvis, heart fat, longissimus dorsi area, marbling score, or YG of steers wintered on a high gain winter wheat system, low gain winter wheat system, or native range. Only HCW was greatest for steers on high-gain winter wheat when slaughtered at a common backfat (Hersom et al., 2004). In contrast, Neel et al. (2007) reported that Angus steers exhibiting low (0.23 kg/d), medium (0.45 kg/d), or high rates of gain (0.68 kg/d) during winter affected carcass characteristics when slaughtered at equal time end points; HCW, DP, and QG were greater (P < 0.05) for high-gain steers compared with low- or medium-gain steers. In the current experiment, as noted previously, rib-fat thickness, longissimius dorsi area size, and quality grades were not affected by backgrounding systems, indicating that an extensive grazing backgrounding system may not also negatively influence consumer preference for lean meat, which compels the producer to enhance lean meat production (Schaake et al., 1993). Similarly, differences in marbling scores of carcasses among calves in backgrounding systems were not detected (P > 0.05) in the current experiment. In contrast, Hersom et al. (2004) mentioned that winter grazing also affects fat deposition in animals due to differences in energy intake, which can be reflected by differences in marbling scores of animals. Thus, the effect of winter grazing on carcass characteristics varies and may be influenced by the type of forage grazed, age of cattle, and biological type of cattle or different implant strategy employed. Finally, the current experiment suggests that backgrounding calves on swathed grazing barley or swathed grazing millet systems will not adversely affect finishing performance and carcass characteristics compared with backgrounding calves in a traditional drylot pen system.

System Cost Backgrounding Phase. Feed cost of BAR calves ($0.92/calf/d) was sim-

ilar (P > 0.05) to that of MILL calves ($1.04/calf/d) and was lower (P < 0.05) than DL calves ($1.22/calf/d; Table 5). Crop production costs were higher and yield lower for the millet, which results in a higher forage cost for MILL ($0.34/calf/d) compared with BARL. Forage cost for DL calves ($0.49/calf/d) was highest among the 3 systems, and BAR calves had the lowest forage cost at $0.23/calf/d. Kelln et al. (2011) obtained feed costs of swath barley grazed ($0.31/cow/d) and DL wintering ($0.86/cow/d) cows that were lower than the findings of the current experiment. Higher costs in the current experiment are partly due to the extra supplementation required to achieve the targeted ADG. In the Kelln et al. (2011) experiment, only maintenance needs of the cows were met without any supplementation. A reason for the greater feed cost in the drylot system in our experiment compared with Kelln et al. (2011; $0.86/cow/d), may be due to purchasing the hay from an outside source as opposed to producing the hay at the experimental site like in Kelln et al. (2011). Other direct costs (i.e., bedding, treatment costs) were higher (P < 0.05) for the DL ($0.10/ calf/d) compared with the MILL or BAR ($0.06/calf/d) system. This was partly due to the use of residual or spoiled feed for bedding in swathed grazed systems, thereby decreasing the need for additional bedding and to variations in medicine treatment costs between systems. Total yardage costs of BAR ($0.38/calf/d) and MILL ($0.37/calf/d) were equal (P > 0.05), and 50% less than that of DL ($0.75/calf/d) system. This difference can be attributed to 50% lower machinery and labor costs (data not shown) for BAR and MILL compared with DL. Similarly, McCartney et al. (2004) reported 38% less labor for barley-swath-grazed compared with traditional DL-fed cows. Total cost of production was the greatest (P < 0.05) in the DL system ($2.06/calf/d), but was similar (P > 0.05) for BAR ($1.38/calf/d) and MILL ($1.48/ calf/d) systems. Lardner (2004a) compared the potential of swath-grazed

Alternative backgrounding systems for beef calves

Table 4. Effect of backgrounding system on carcass characteristics of calves over 2 yr Backgrounding system1 Item

BAR

MILL

DL

SEM

P-value

Shrunk ship weight, kg HCW, kg Dressing percentage, % Grade fat,2 mm Estimated lean yield,3 % Longissimus dorsi area, cm × cm Marbling score4   Percentage with score 5   Percentage with score 6   Percentage with score 7   Percentage with score 8

609.5 356.0 57.8 10.2 60.8 98.7

603.3 349.8 57.7 10.7 60.1 96.1

609.7 357.4 58.2 10.4 60.3 97.1

12.24 7.00 0.32 0.88 0.72 1.49

0.86 0.61 0.54 0.87 0.64 0.26

4.6 6.1 21.3 64.3

6.3 7.7 18.5 63.8

1.3 11.2 22.7 61.0

3.18 2.24 6.57 6.45

0.43 0.10 0.81 0.88

Means within a row with different superscripts differ (P < 0.05). BAR = swathed barley grazing; MILL = swathed millet grazing; DL = drylot pen feeding. 2 Grade fat is a measure of subcutaneous fat assessed perpendicular to the outside surface, within the fourth quarter of the rib-eye at the minimum point of thickness. 3 Estimated lean yield = 63.65 + 1.05 (muscle score) − 0.76 (grade fat). 4 Marbling score: 5 = moderate; 6 = modest; 7 = small; 8 = slight; 9 = traces, and 10 = devoid. a,b 1

forage corn and barley for weaned beef calves and revealed that total crop production expenses for corn were 67% higher; however, cost of

gain ($2.15 per kg for corn vs. $2.26 per kg for barley) for both crops was similar. Furthermore, Lardner (2004a) concluded that high crop production

Table 5. Effect of backgrounding systems on cost of gain over 3 yr Backgrounding system1 Item

BAR

MILL

DL

SEM

P-value

Backgrounding cost of gain   Feed cost, $/calf per day   Direct cost, $/calf per day   Yardage cost, $/calf per day   Total production cost, $/calf   per day   Cost of gain, $/kg Feedlot cost of gain   Feed cost, $/calf per day   Direct cost, $/calf per day   Yardage cost, $/calf per day   Total production cost, $/calf per day   Cost of gain, $/kg

  0.92b 0.08b 0.38b

  1.04ab 0.07b 0.37b

  1.22a 0.09a 0.75a

  0.099 0.007 0.037

  0.04 <0.01 <0.01

1.38b 1.70b   2.43 0.01 0.44

1.48b 2.45a   2.43 0.01 0.44

2.06a 2.47a   2.43 0.01 0.44

0.007 0.160   0.047 0.002 0.028

<0.01 <0.01   0.99 0.68 1.00

2.88 1.64

2.88 1.63

2.88 1.66

0.047 0.020

0.99 0.12

Means within a row with different superscripts differ (P < 0.05). BAR = swathed barley grazing; MILL = swathed millet grazing; DL = drylot pen feeding.

a,b 1

549

expenses were responsible for the high COG in both crops and backgrounding of calves on conventional drylot system could have been more cost effective. Lardner (2004b) also reported cost of gain of calves backgrounded on foxtail millet (cv. Golden German) to be around $0.60 per kg, although the grazing period was only 26 d. Based on these data, the author suggested that for better economic gain of calves, total grazing period should be at least 60 d. In addition, others (Kelln et al., 2011) found that in extensive winter grazing, an increase in soil fertility was observed due to retention of soil nutrients leading to increased production of subsequent crop as a result of spread of manure and urine. The value of ungrazed feed was outside the scope of this experiment. Total cost of production would be reduced further in the swathed barley and millet grazed backgrounding systems, if the stocking rate would have increased in the current experiment as suggested by McCartney et al. (2008). The swathed barley grazed system ($1.70/kg) had 30 and 31% lower (P < 0.05) COG compared with MILL ($2.45/kg) and DL ($2.47/ kg) systems, respectively. The higher COG for MILL compared with BAR even with similar cost of production was due to the lower daily gain (Table 1; 0.6 vs. 0.8 kg/d barley swath) of MILL calves. In parallel, DL calves had similar daily gain to BAR calves (Table 1); however, COG was greater, which is due to 49% higher total cost of production in the DL system. Cost of Gain for Finishing. Total cost of production for the feedlot finishing phase of the experiment included feed costs, direct costs, and yardage costs. Costs were divided by ADG (kg) to estimate COG (Table 5). There was no difference in the total feed cost, direct cost, yardage cost, and total production cost of calves during finishing due to previous BG systems. Finishing COG was numerically lower (P = 0.115) for swathgrazed calves than for DL calves. Specifically, MILL calves finishing COG was slightly lower among these BG systems, likely due to the greater

550

Kumar et al.

daily gain (1.65 kg/d MILL vs. 1.63 kg/d BAR and 1.61 kg/d DL) during subsequent feedlot feeding. Overall, this experiment indicated that swathed barley grazing and swathed millet grazing during backgrounding had no negative effects on calf performance and system cost during the subsequent finishing trial.

IMPLICATIONS Results of this experiment indicate that BAR is a viable option for backgrounding fall weaned beef calves in western Canada. Backgrounding calves in the BAR system resulted in similar performance as calves managed in DL system. In addition, COG was lower for calves in the BAR system compared with MILL and DL systems. In contrast, MILL and DL system COG was similar during backgrounding because MILL calf performance was lower than BAR calves. Backgrounding calves in BAR, MILL, or DL systems resulted in similar finishing performance and carcass characteristics. This suggests that BAR backgrounding systems can be more profitable than DL and are real alternatives to manage beef calves in a more environmentally sustainable manner.

ACKNOWLEDGMENTS This experiment was funded by the Saskatchewan Agriculture Development Fund (Regina, SK), Saskatchewan Cattle Marketing Deduction Fund (Regina, SK), Advancing Canadian Agriculture, and Agri-Food Fund (Ottawa, ON) and Western Beef Development Centre (Humboldt, SK). The authors are extremely grateful to George Widdifield, Leah Pearce (both with Western Beef Devopment Centre, Lanigan, SK, Canada), and Teresa Binetruy (University of Saskatchewan, Saskatoon, SK, Canada) for assistance in the field and data management during this experiment and Enkhjargal Darambazar (Western Beef Development Centre, Lanigan, SK, Canada) for her editing of this manuscript.

LITERATURE CITED Aasen, A., V. S. Baron, G. W. Clayton, A. C. Dick, and D. H. McCartney. 2004. Swath grazing potential of spring cereals, field pea and mixtures with other species. Can. J. Anim. Sci. 84:1051–1058. Allen, M. S. 2000. Effects of diet on short term regulation of feed intake by lactating dairy cattle. J. Dairy Sci. 83:1598–1624. AOAC. 2000. Official Methods of Analysis. 17th ed. AOAC Int., Gaithersburg, MD. Baron, V. S., A. C. Dick, D. McCartney, J. A. Basarab, and E. K. Okine. 2006. Carrying capacity, utilization, and weathering of swathed whole plant barley. Agron. J. 98:714–721. Bergen, R. D., J. J. McKinnon, D. A. Christensen, N. Kohle, and A. Belanger. 1997. Use of real-time ultrasound to evaluate live animal carcass traits in young performance-tested beef bulls. J. Anim. Sci. 75:2300–2307. Canadian Council on Animal Care. 1993. Guide to the care and use of experimental animals. Vol. 1. 2nd E. D. Olfert, B. M. Cross, and A. A. McWilliam, ed. CCAC, Ottawa, Ontario. Canada. Carstens, G. E., D. E. Johnson, M. A. Ellenburger, and J. D. Tatum. 1991. Physical and chemical components of the empty body during compensatory growth in beef steers. J. Anim. Sci. 69:3251–3264. Choat, W. T., C. R. Krehbiel, G. C. Duff, R. E. Kirksey, L. M. Lauriault, J. D. Rivera, B. M. Capitan, D. A. Walker, G. B. Donart, and C. L. Goad. 2003. Influence of grazing dormant native range or winter wheat pasture on subsequent finishing cattle performance, carcass characteristics, and ruminal metabolism. J. Anim. Sci. 81:3191–3201. Cordova, F. J., J. D. Wallace, and R. D. Pieper. 1978. Forage intake by grazing livestock: A review. J. Range Manage. 31:430–438. Damiran, D. 2005. Palatability of Mongolian rangeland plants. Page 92 in Cir. Inform. No. 3. Eastern Oregon Agric. Res. Sta. Union. Oregon State University, Corvallis. Drouillard, J. S., and G. L. Kuhl. 1999. Effects of previous grazing nutrition and management on feedlot performance of Cattle. J. Anim. Sci. 77:136–146. Gould, R., and M. Price. 1998. Research makes sense. Page 15. Canadian Cattleman. Nov. 1998: Vol. 42. Saskatchewan, Canada. Hersom, M. J., G. W. Horn, C. R. Krehbiel, and W. A. Phillips. 2004. Effect of live weight gain of steers during winter grazing: I. Feedlot performance, carcass characteristics, and body composition of beef steers. J. Anim. Sci. 82:262–272. Jungnitsch, P. 2008. Effect of winter feeding system on soil nutrients, forage growth, forage

growth, animal performance, and economics. MS thesis. Univ. Saskatchewan, Saskatoon, Canada. Karantininis, K. A., T. I. McNinch, and W. J. Brown. 1997. Risk and (re-) organization in agriculture: The economics of backgrounding cattle in Saskatchewan. Can. J. Agric. Econ. 45:310–316. Kelln, B. M., H. A. Lardner, J. J. McKinnon, J. R. Campbell, K. Larson, and D. Damiran. 2011. Effect of winter feeding system on beef cow performance, reproductive efficiency, and system cost. Prof. Anim. Sci. 27:410–421. Klein, L. 2008. Suitability of cool and warm season cereal crops for swath grazing. Government of Saskatchewan. Accessed Oct. 2008. http://www.agriculture.gov.sk.ca/ Default.aspx?DN=de1b8105-4886-4c13-8d3b692c9d0a632a. Klopfenstein, T., R. Cooper, D. J. Jordon, D. Shain, T. Milton, C. Calkins, and C. Rossi. 2000. Effects of backgrounding and growing programs on beef carcass quality and yield. J. Anim. Sci. 77:1–11. Lardner, H. A. 2004a. Backgrounding of calves on corn and barley. WBDC Fact Sheet #2004–02. Western Beef Development Centre, Humboldt, Saskatchewan, Canada. Lardner, H. A. 2004b. Backgrounding of calves on Golden German millet swath. WBDC Fact Sheet #2004–01. Western Beef Development Centre, Humboldt, Saskatchewan, Canada. Lewis, J. M., T. J. Klopfenstein, and R. A. Stock. 1990. Effects of rate of gain during winter on subsequent grazing and finishing performance. J. Anim. Sci. 68:2525–2529. Mackay, W. S., J. C. Whittier, D. Couch, and D. N. Schutz. 2003. Inter seeding triticale with windrowed millet as a winter feeding program for developing heifers. Proc. West. Sec. Am. Soc. Anim. Sci. 54:238–241. McCartney, D., J. A. Basarab, E. K. Okine, V. S. Baron, and A. J. Depalme. 2004. Alternative fall and winter feeding systems for spring calving beef cows. Can. J. Anim. Sci. 84:511–522. McCartney, D., J. Fraser, and A. Ohama. 2008. Annual cool season crops for grazing by beef cattle. A Canadian Review. Can. J. Anim. Sci. 88:517–533. Neel, J. P. S., J. P. Fontenot, W. M. Clapham, S. K. Duckett, E. E. D. Felton, G. Scaglia, and W. M. Bryan. 2007. Effect of winter stocker growth rate and finishing system on animal performance and carcass characteristics. J. Anim. Sci. 85:2012–2018. NRC. 1996. Nutrient Requirements of Beef Cattle. 7th ed. Natl. Acad. Press, Washington, DC. NRC. 2000. Nutrient Requirements of Beef Cattle. 7th rev. ed. Natl. Acad. Press, Washington, DC.

Alternative backgrounding systems for beef calves Perillat, B. J., W. J. Brown, and R. D. H. Cohen. 2003. A risk efficiency analysis of backgrounding and finishing steers on pasture in Saskatchewan. Can. J. Agric. Sys. 80:213–233.

SMA (Saskatchewan Ministry of Agriculture). 2008–2009. Farm machinery custom and rental rate guide 2008–2009. SMA, Regina, Saskatchewan, Canada.

Phillips, W. A., J. W. Holloway, and S. W. Coleman. 1991. Effect of pre- and post weaning management system on the performance Brahman crossbred feeder calves. J. Anim. Sci. 69:3102–3111.

Smith, S. C., D. R. Gill, T. R. Evicks, and J. Prawl. 2000. Effect of selected characteristics on the sale price of feeder cattle in eastern Oklahoma: 1997 and 1999 summary. Pages 14–19 in Okla. Agric. Exp. Stn. Res. Rep. 980. Oklahoma State Univ., Stillwater.

Saskatchewan Soil Survey. 1992. The soils of Prairie Rose rural Municipality No. 309, Saskatchewan, Saskatchewan Institute of Pedology, Univ. Saskatchewan, Saskatoon, Canada.

Tatum, J. D., B. J. Klein, F. L. Williams, and R. A. Bowling. 1988. Influence of diet growth rate and carcass composition of steers differing in frame and muscle thickness. J. Anim. Sci. 66:1942–1954.

Schaake, S. L., G. C. Shelley, E. Halpin, L. W. Grimes, R. B. Brown, D. L. Cross, and C. E. Thompson. 1993. Carcass and meat sensory traits of steers finished on fescue and clover, summer forage, or for different periods in the drylot. J. Anim. Sci. 71:3199–3205.

Van De Kerckhove, A. Y., H. A. Lardner, K. J. W. Walburger, J. J. McKinnon, and P. Yu. 2011. Effects of supplementing spring-calving beef cows grazing barley crop residue with wheat-corn blend dried distillers’ grain plus solubles on animal performance and estimated dry matter intake. Prof. Anim. Sci. 27:219–227.

SMA (Saskatchewan Ministry of Agriculture). 1998. Agricultural Statistics 1998. Saskatchewan Agriculture and Food, Statistics Branch. Regina, Saskatchewan, Canada.

Van Soest, P. J. 1994. Nutritional Ecology of the Ruminant. 2nd ed. Cornell University Press, Ithaca, NY.

551

Van Soest, P. J., J. B. Robertson, and B. A. Lewis. 1991. Methods for dietary fiber neutral detergent fiber and nonstarch polysaccharides in relation to animal nutrition. J. Dairy Sci. 74:3583–3597. Volesky, J. D., D. C. Adams, and R. T. Clark. 2002. Windrow grazing and baled-hay feeding strategies for wintering calves. J. Range Manage. 55:23–32. Weiss, W. P., H. R. Conrad, and N. R. St. Pierre. 1992. A theoretically-based model for predicting total digestible nutrient values of forages and concentrates. Anim. Feed Sci. Technol. 39:95–110. White, T. W., F. G. Hembry, P. E. Humes, and A. M. Saxton. 1987. Influence of wintering weight change on subsequent pasture and feedlot performance by steers. J. Anim. Sci. 64:32–35. Zinn, R. A., F. N. Owens, and R. A. Ware. 2002. Flaking corn: processing mechanics, quality standard, and impacts on energy availability and performance of feedlot cattle. J. Anim. Sci. 80:1145–1156.