Comparison of cool-season perennial grasses for forage production and nutritive value, steer performance, and economic analysis1

The Professional Animal Scientist 29 (2013):403–412

©2013 American Registry of Professional Animal Scientists

Comparison of cool-season perennial grasses for forage production and nutritive value, steer performance, and economic analysis1

H. A. Lardner,*†2 C. I. Ward,‡ E. Darambazar,† and D. Damiran*† *Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5A8, Canada; †Western Beef Development Centre, Humboldt, Saskatchewan S0K 2A0, Canada; and ‡Saskatchewan Ministry of Agriculture, 38 5th Ave. N, Yorkton SK S3N 0Y8, Canada

ABSTRACT Over 3 yr, cool-season perennial grasses, including Carlton smooth bromegrass (Bromus inermis Leyss.; SB), Paddock meadow bromegrass (Bromus riparius Rehm.; MB), AC Knowles hybrid bromegrass (B. riparius × B. inermis; HB), AC Goliath crested wheatgrass [Agropyron cristatum (L.) Gaertn.; CW], and Courtenay tall fescue (Festuca arundinacea Schreb.; TF), were established in ten 0.8-ha paddocks (2 per cultivar) at Western Beef Development Centre’s Termuende Research Ranch near Lanigan, Saskatchewan, to evaluate the effect of grass species on forage DM production and nutritive value, steer performance, and economic analysis. Eighty-four stocker calves (Bos tauThis research was supported in part by grants from the Saskatchewan Agriculture Development Fund, Saskatchewan Beef Development Board, and Western Beef Development Centre. 2 Corresponding author: blardner.wbdc@ pami.ca 1

rus; BW = 323 ± 5 kg) were randomly allocated to all 10 paddocks and managed in a put-and-take grazing system. Tester steers were used to measure performance, and additional steers were added as necessary to equalize available forage among paddocks. Grazing was initiated on May 27, May 28, and June 1 in yr 1, 2, and 3, respectively. Year 1 and total-3-yr forage DM were greatest (P = 0.04) for CW compared with other grasses. Tall fescue CP was greatest at the beginning of the grazing period in yr 1, whereas TF NDF was least at the start and middle of the graze period in yr 1. Across all years, the greatest ADG was observed for steers on CW and HB treatments, which did not differ (P = 0.55). Animal grazing days (AGD) were greater (P < 0.05) for TF in yr 2 and 3 than AGD on SB paddocks. Total-3-yr AGD for TF were 26 and 39% greater than those of SB and CW, respectively. Tall fescue produced more BW gain per hectare annually (P = 0.03) and 3 yr total than did SB paddocks. Total expenses to manage a stocker program were 41% lower compared with growing an annual

crop. Stocker profitability was similar (P = 0.08) from grazing a TF pasture enterprise ($104/ha), compared with growing a barley crop, averaged over 3 yr ($114/ha). Key words: cool-season grass, forage production, grazing, stocker

INTRODUCTION Crested wheatgrass [Agropyron cristatum (L.) Gaertn.] and smooth bromegrass (Bromus inermis Leyss.) have long been used for both hay production and pasture grazing in western Canada (Smith et al., 1986; Vogel et al., 1993). High forage nutritive value and early spring growth of crested wheatgrass make it suitable in complementary grazing systems (McKendrick and Sharp, 1970). Crested wheatgrass is very drought tolerant, is winter hardy, and tends to persist for long periods of time. Smooth bromegrass is a rhizomatous sod former that is winter hardy and drought tolerant (Smith et al., 1986).

404 More recently, meadow bromegrass (Bromus riparius Rehm.), hybrid bromegrass (B. riparius × B. inermis), and tall fescue (Festuca arundinacea Schreb.) have been studied for pasture use in western Canada. Meadow bromegrass, a bunch-type grass with basal leaf growth, has increased regrowth compared with smooth bromegrass, making this species more suitable for pasture rather than hay production. Meadow bromegrass is often used in mixtures with alfalfa (Medicago sativa L.), but there is little published data on its performance in pure stands (Knowles et al., 1993). Agriculture Canada’s breeding program generated hybrid bromegrass, which is a cross between smooth and meadow bromegrass. This species was selected to have characteristics that are intermediate to the 2 parental lines (Coulman, 2004) and is suitable for both hay and pasture production (Knowles and Baron, 1990). Tall fescue is a deep-rooted, bunchtype grass that is less winter hardy than is smooth bromegrass. Tall fescue has been shown to provide excellent autumn and winter grazing in temperate areas of the United States and Canada (Smith et al., 1986). It is also important to consider the economic analysis of pasture systems in addition to forage DM production (Adams et al., 1994). In an experiment involving Saskatchewan producers, Highmoor (2005) reported the daily costs of feeding, bedding, and yardage were $1.00 and $0.79 per cow, respectively. This daily total cost of $1.79 per cow was $1.00 more per cow than the average grazing cost of $0.80 per cow (McCartney et al., 2004). Lang (2006a) also reported grazing costs ranged from $0.69 to $0.80/d per cow for 2002 to 2005 compared with winter feed costs, which ranged from $0.99 to $1.28/d per cow. Few cool-season grasses have been evaluated for livestock performance and stand persistence under grazed conditions before commercial release (Lardner et al., 2003). Most forage testing occurs in small plots using mechanical defoliation methods, such as mowing, which fails to impose grazing

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animal effects, such as pulling, treading, and nutrient deposition, which may cause different responses than clipping (McCartney and Bittman, 1994). This experiment compared 5 perennial cool-season grasses for forage DM yield and nutritive value, steer performance, and economic analysis compared with growing annual crops.

MATERIALS AND METHODS The experiment was conducted over 3 consecutive yr at the Western Beef Development Center’s Termuende Research Ranch near Lanigan, Saskatchewan, Canada (51°51′N; 105°02′W) on a mixture of Oxbow Orthic Black and carbonated Oxbow soils with a loam texture (Saskatchewan Soil Survey, 1992). Topography of the pastures (NW-22-33-21-W2) was gently to moderately hummocky. Established monoculture pastures of 5 perennial cool-season grasses were grazed from May to September in the summers of 2005 (yr 1), 2006 (yr 2), and 2007 (yr 3) to compare forage DM yield, forage nutritive value, and performance of grazing cattle. Grass species included 1) AC Knowles hybrid bromegrass (B. riparius × B. inermis; HB); 2) Carlton smooth bromegrass (B. inermis Leyss.; SB); 3) Paddock meadow bromegrass (B. riparius Rehm.; MB); 4) AC Goliath crested wheatgrass [A. cristatum (L.) Gaertn.; CW]; and 5) Courtenay endophyte-free tall fescue (F. arundinacea Schreb.; TF). Smooth bromegrass, HB, and MB were each established using a no-till drill (John Deere, Moline, IL) on May 22, 1999, at a rate of 10 (SB) and 12 (HB, MB) kg/ha in 6 paddocks of 0.8 ha each, with 2 paddocks of each of the 3 grasses. Crested wheatgrass and TF were each established using a no-till drill (John Deere) adjacent to these paddocks on May 28, 2003, at a rate of 10 (CW) and 5 (TF) kg/ha in 4 paddocks of 0.8 ha each, with 2 paddocks of each grass species. Before establishment, the areas were sprayed with glyphosate at 2.0 kg/ha of active ingredient to facilitate weed con-

trol. Postestablishment weed control included 0.288 kg/ha of active ingredient fenoxaprop-p-ethyl (Acclaim Extra, Bayer CropScience, Pittsburgh, PA), 0.334 kg/ha of active ingredient bromoxymil (Buctril M, Bayer CropScience), and 0.198 kg/ha of active ingredient tralkoxydim (Achieve, Syngenta, Wilmington, DE). Nitrogen and P fertilizer was applied before grazing each year. All paddocks were fertilized with 79 kg/ha N (urea) and 23 kg/ha P2O5 (diphosphorus pentoxide) each spring via coulter disc application according to soil-test recommendations.

Forage Determination and Nutritive Value Forage DM yield was determined using a cage comparison technique (Klingman et al., 1943). Each paddock had 3 randomly placed exclusion cages (1.8 × 1.2 m) allocated before grazing. Available forage (kg of DM/ ha) was measured at the start of each grazing period by clipping six 0.25m2 quadrats per grass, 1 inside and 1 outside of each cage to a stubble height of 2.5 cm. After clipping, cages were randomly repositioned within the paddock. Previously harvested areas were not reharvested. Forage DM yield was determined using the following formula (Thompson et al., 2003): Cumulative DM yield = start of experiment initial growth + (wk 1 inside cage clip − start of experiment initial growth) + (wk 2 inside cage clip − wk 1 outside cage clip) + (wk 3 inside cage clip − wk 2 outside cage clip) + . . . Clipped samples from outside the exclusion cages were used for forage nutritive-value analyses. All samples were dried to a constant weight (55°C) in a forced-air oven and ground through a 1-mm screen

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using a Wiley grinder (Thomas Wiley Laboratory Mill, Model 4, Thomas Scientific, Swedesboro, NJ). Forage nutritive-value analyses included CP, NDF, and ADF at the initiation, midpoint, and termination of each grazing period. Forage DM was determined by oven drying the samples in a forcedair oven at 55°C until a constant weight was reached. Crude protein (N × 6.25) was analyzed using a Leco FP428 Nitrogen Analyzer (Leco Corporation, St. Joseph, MI). Neutral detergent fiber and ADF were determined by the batch procedures using an ANKOM 200 Fiber Digester outlined by ANKOM Technology Corp. (Fairport, NY).

Environmental Data Monthly average precipitation and temperature were recorded at a meteorological station at the Termuende Research Ranch, 1 km east of the pastures. Historical weather data were obtained from Environment Canada climate data for Esk, Saskatchewan, approximately 5 km southeast of the pastures (51°48′N, 104°51′W; www. climate.weatheroffice.ec.gc.ca). Data are presented from April to October each year to provide rainfall and temperatures during the grazing period.

Grazing Management Each year, 84 crossbred British × Continental (Bos taurus) steers (yr 1, initial BW = 337 ± 4 kg; yr 2, initial BW = 308 ± 3 kg; yr 3, initial BW = 325 ± 6 kg) were purchased and stratified by BW, tagged to allow individual identification, and randomly allocated to 1 of 10 paddocks. Steers had ad libitum access to a 1:1 range mineral (Feed Rite Mineral Ltd., Winnipeg, MB, Canada) that contained 16% Ca, 16% P (guaranteed minimum of 10,000 mg/kg of Zn, 125 mg/kg of I, 4,000 mg/kg of Cu, 5,300 mg/kg of Mg, 40 mg/kg of Co, 450 mg/kg of Fe, 200 IU/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 of I and 100 mg/kg of Co) in mineral feeders on pasture. Steers were implanted before the experiment start with Ralgro (36 mg of Zeranol; Schering-Plough Corp., Kenilworth, NJ) and vaccinated against bovine respiratory syncytial virus, infectious bovine rhinotracheitis, bovine viral diarrhea, and parainfluenza 3 (Starvac 4 plus; Novartis Animal Health Canada Inc., Mississauga, Ontario, Canada), and a Clostridium 8-way modified live vaccine (Covexin 8; Schering-Plough Animal Health, Guelph, Ontario, Canada). All animals were handled according to the Guidelines of the Canadian Council on Animal Care (1993). Grazing was initiated following clipping to determine initial forage biomass for each grass species. Stocking rate was then adjusted to provide similar initial forage allowance per animal at the start of the grazing period. Individual paddocks were separated with electric fencing, and water was provided ad libitum to all paddocks in stock troughs through surface pipelines. A variable stocking rate was managed using a put-andtake grazing system with 3 randomly chosen tester steers per paddock (Mott and Lucas, 1952). Tester steers remained on their designated pastures for the duration of the grazing period, whereas additional put-and-take steers, similar in BW, were added or removed from pastures to maintain similar forage availability and maturity in each pasture type. Steers remained on each replicate paddock until grasses were grazed to a uniform stubble height of approximately 5 cm, with no additional regrowth observed in yr 1 and 3 to justify additional grazing. The experiment had 1 grazing period in yr 1 and 3, whereas in yr 2, because of very good growing conditions and above-normal rainfall (Table 1), 2 grazing periods were obtained. All grasses were grazed late May to early September. The pastures were grazed for 48 d (May 27 to July 14) in yr 1, 81 d (period 1, May 27 to July 14; period 2, August 5 to September 7) in yr 2, and 84 d (June 1 to August 23) in yr 3. Before the start of

the experiment each year and between grazing periods in yr 2, steers were allowed to graze a crested wheatgrass– smooth bromegrass common pasture.

Animal Measurement Tester steers were weighed over 2 consecutive days at approximately 0800 h without shrinking the cattle, and 2-d BW were averaged. Body weights were taken at the start and finish of the experiment and at 7-d intervals during the experiment. Average daily gain was determined using only tester-steer BW change between initiation and finish of each grazing period. All BW data were converted to animal unit equivalents (AU) to account for differences in steer BW (AU = BW0.75/4550.75; Vallentine, 1990) and were expressed as animal grazing days (AGD) per ha using the following equation: AGD = [Σ(animal unit equivalent × days on pasture)]/pasture area. BW gain per hectare was calculated for each grass species using the following equation (Mott and Lucas, 1952): BW gain/ha = ADG of steers × AGD.

Statistical Analysis Statistical analysis was conducted using the MIXED procedure of SAS for ANOVA (SAS Institute Inc., Cary, NC). The experimental model was Yab = μ + ρa + αb + eab, where a is the block (year), b is the grass species, 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. Steer ADG, AGD, BW gain per hectare, forage yield, and forage nutritive value were analyzed as a randomized complete block design with the 5 grass species as treatments and with 2 replicates per grass species per year. In yr 2, data were calculated and averaged between the 2 grazing periods. Forage nutritive values were analyzed using

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Table 1. Weather data for grazing seasons 2005, 2006, and 2007 at Termuende Research Ranch and 30-yr1 average 2005 Item April May June July August September October Total   April May June July August September October Total 1

2006

Maximum temperature, °C

Minimum temperature, °C

Rainfall, mm

Maximum temperature, °C

Minimum temperature, °C

Rainfall, mm

12.3 16.5 20.0 25.0 22.7 18.4 11.2

−0.6 2.6 9.7 10.6 8.5 5.3 −1.3

8.8 53.0 66.7 38.2 96.8 87.6 16.4 367.5

12.3 17.5 22.4 26.1 25.9 18.2 6.0

0.3 5.8 11.1 12.5 10.1 5.5 −3.5

41.0 99.2 89.0 23.8 34.8 121.0 55.2 464.0

−2.1 4.5 9.0 11.4 10.1 4.8 −1.4

21.8 46.3 59.1 64.9 47.7 31.8 17.9 289.5

 

 

 

2007

 

9.0 17.8 21.7 24.1 21.7 17.1 11.3

 

−2.1 5.1 9.0 12.4 9.1 3.8 0.0

8.6 61.8 94.6 44.6 63.4 38.0 15.6 326.6

 

9.5 17.7 22.0 24.7 23.9 17.2 9.8

  30-yr average

 

Historical weather data obtained from Esk, SK (51°48′N, 104°51′W) approximately 5 km from the experiment site.

PROC MIXED for 3 sample times, at the initiation, mid-point, and finish of each grazing period. Where significant differences were indicated (P < 0.05), means were separated at the 5% level of significance using Tukey’s procedure (Steel et al., 1997).

Economic Analysis An economic analysis of stocker profitability from grazing each grass species (grazing system) was calculated each year and then compared with growing barley grain (annual cropping system) on the same land. Revenues, costs, and profit were determined for all grasses and compared with revenues, costs, and profit resulting had the land been cropped with an annual barley crop. All dollar values expressed are in Canadian dollars. Revenues generated from the forage-based systems were the result of custom grazing stocker cattle based on kilograms of BW gain. In this calculation, the custom grazing rate was $0.86/kg for 2005 and 2006 and $0.99/kg for 2007. The rate was determined using Saskatchewan

prices from May through September in 2005, 2006, and 2007 for a 322-kg, medium-framed steer (Canfax, 2007). The grazing rate was then multiplied by BW gain per hectare (Table 4) to determine revenue generated from each grass species. In each grazing system, variable or operating costs included supplemental feed and minerals, veterinary and medicine costs, fertilizer, and custom work. Fixed costs in the grazing system included fence and water repair, fence and water depreciation and investment, insurance and license, grass establishment costs, and land rent. Crested wheatgrass was assumed a stand life of 20 yr, so establishment costs were amortized for that period of time, whereas TF and all bromegrasses (HB, MB, SB) were assumed a stand life of 12 yr, so costs were amortized for that time. There was a single herbicide cost of $109.84/ha (SMA, 2008a) and $12.15/ ha for application. All field work was valued a custom rate per hectare from the Saskatchewan Ministry of Agriculture’s Farm Machinery Custom and Rental Rate Guide (SMA, 2008a). At

seeding, 56 kg of N/ha was placed with the seed. Each year, all pastures were fertilized with 79 kg of N/ha and 22 kg of P/ha of liquid fertilizer. Supplemental salt and minerals was estimated to be $8.08/ha (Lardner, 2004). Veterinary and medicine costs were estimated at $12.35/ha. Yearly fence and water repair costs were estimated at $3.43/ha and fence, water depreciation, and investment were estimated at $11.14/ha. In addition, insurance and licenses were estimated to cost $4.69/ha. Finally, the cost of land rent was assumed to be $61.75/ ha each year of the experiment (SMA, 2008a). For comparison purposes, revenue was calculated by using average bushel yield for barley per hectare for the Lanigan, Saskatchewan, area according to SMA (2008b) for each year. The bushel yield was multiplied by the Canadian Wheat Board final price for barley (1 CW Barley) less the shipping cost. Estimation of costs to annual crop the land were calculated using Saskatchewan Ministry of Agriculture Crop Planning Guides for the Black

Stocker performance grazing cool-season perennial grasses

Table 2. Cumulative biomass of grass pastures (kg of DM/ha) Item

CW1

HB

SB

MB

TF

SEM

2005 2006 2007 Total

7,514a 3,293 5,985 16,792

3,835b 4,799 6,329 14,963

3,197b 3,879 4,455 11,531

2,868b 5,712 6,617 15,197

3,932b 4,887 5,931 14,750

716 634 517 —

Means within a row with different superscripts differ (P < 0.05). CW = AC Goliath crested wheatgrass; HB = AC Knowles hybrid bromegrass; SB = Carlton smooth bromegrass; MB = Paddock meadow bromegrass; TF = Courtenay endophyte-free tall fescue.

a,b 1

Soil Zone (SMA, 2008b). Costs were based on the crop being direct seeded into stubble. Variable costs included seed, chemical, fertilizer, machinery fuel and repairs, crop insurance premium, custom work, interest, utilities, and office and miscellaneous expenses. Fixed costs included building repair, machinery and building depreciation and interest, insurance, licenses, and land rent (SMA, 2008b).

RESULTS AND DISCUSSION Environmental Data Differences in maximum and minimum temperatures between years and 30-yr averages were observed, with 6 to 8% higher temperatures in July and August 2006 (Table 1). The major difference was in rainfall, with 27, 61, and 13% above normal observed April to October in yr 1, yr 2, and yr 3, respectively. The difference in rainfall between yr 1 and yr 2 was approximately 26% and between yr 2 and yr 3, approximately 42%, with above normal observed in yr 2. In this experiment, rainfall levels above normal were observed September to October 2005 and May to June 2006, which allowed for 2 grazing periods in 2006.

Forage Yield and Nutritive Value Forage DM yield of the 5 cool-season grasses are presented in Table 2. The DM yield of SB and MB paddocks was similar to yields reported

by Thompson et al. (2003). This fact suggests that the yield of bromegrass forage in this experiment is representative of potential DM production of an established pasture when fertilized on a yearly basis. In yr 1, CW paddocks produced greater (P = 0.03) DM yield than did the other grasses. Earlier in the grazing period (May) in yr 1, CW was vegetative, which may explain the greater DM yield compared with other grasses. In this experiment, HB, SB, and MB were very productive and produced similar DM biomass (3,998 kg/ha) to those reported by Lardner et al. (2000) (3,911 kg/ha) in an experiment evaluating cool-season species at 5 different locations in the Parkland of Saskatchewan. In yr 1, the 3 bromegrasses had similar production, but in yr 2 and yr 3, the distribution of DM yield between these species indicates the HB and MB produced more yield compared with SB over the 2 yr. This is in agreement with research regarding these grasses as Van Esbroeck et al. (1995) reported that the first 21 to 28 d following grazing, SB showed a lower leaf area index and growth rate (kg of DM/d) compared with both MB and hybrid bromegrass. The result is that SB has less leaf tissue to generate regrowth. Also, HB and MB are capable of elongating cut tillers, whereas SB cannot do this (Coulman and Knowles, 1995). Only MB had greater DM yield, whereas the other grasses had lesser or similar yield as the reported values (SMA, 2008b) in yr 2 of this experiment. Forage DM yield was greater for HB and MB

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in yr 3 than the 5,200 kg of DM/ ha reported for these varieties for the Black soil zone of Saskatchewan (SMA, 2008b). Comparing total DM yield over all 3 yr (Table 2), CW and MB accumulated the greatest forage biomass. Tall fescue, HB, MB, and CW produced 28, 30, 32, and 46% greater total DM yield than did SB paddocks, respectively. Crested wheatgrass and MB produced greater DM yields more consistently, with TF and HB following a similar trend. Nutritive value of the forages was assessed at initiation, mid-point, and end of the grazing periods (Table 3). Sampling times were chosen to best represent changes in forage nutritive value over the grazing season. In yr 1, differences were detected (P = 0.03) in CP levels between cool-season grasses at the start of grazing. Tall fescue, HB, CW, and SB had greater CP than did MB forage, suggesting greater-quality forage of newly established grasses early in the season. This pattern was also observed in yr 3, although in yr 2, forage CP varied (P = 0.05) between species in the middle of the grazing season. Each grass declined in CP at each sampling time. Crude protein levels were not different (P = 0.07) among all species at the end of the grazing season over all years. Differences were observed (P = 0.04) in NDF and ADF concentrations at each sampling time during the grazing period. Detergent fiber concentrations in TF were lesser in most years at the initiation and midpoint of the grazing season compared with NDF and ADF levels of the other grasses. This would suggest TF could provide adequate-quality forage in late-season grazing. In all established grasses, CP decreased and NDF and ADF increased as the grazing season progressed. These results are similar to an earlier experiment that reported whole-plant nutritive values for MB, SB, and 3 cultivars of HB at 3 stages of plant maturity: vegetative, heading, and anthesis (Ferdinandez and Coulman, 2001). At the vegetative stage of

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Table 3. Nutritive value at sampling time of 5 cool-season perennial grasses1 CP, % Species2 2005  CW  HB  MB  SB  TF  SEM 2006  CW  HB  MB  SB  TF  SEM 2007  CW  HB  MB  SB  TF  SEM

Initial  

21.6a 21.6a 17.5b 20.5a 22.2a 1.21   19.1 20.3 20.4 19.2 17.7 1.08   19.6ab 23.0a 20.8a 18.1b 18.5ab 1.40

NDF, %

Middle  

15.1 12.5 12.9 14.0 13.0 0.75   17.4a 12.7bc 11.2c 12.7bc 14.1b 0.86   13.1 14.3 11.5 10.2 12.5 0.87

Final  

12.2 9.6 12.1 10.5 11.5 0.82   12.2 10.4 8.4 12.6 9.1 0.89   10.1 10.2 8.8 8.4 8.6 0.97

Initial  

52.0a 53.0a 52.8a 54.3a 47.5b 1.03   48.6 52.0 52.3 54.7 52.0 0.99   52.6 52.7 55.2 55.8 53.4 1.07

ADF, %

Middle  

59.0a 59.7a 59.1a 58.8a 55.6b 0.79   54.7c 59.8a 58.1b 59.8a 59.6ab 0.81   60.5a 58.2b 56.1c 60.6a 59.6ab 0.78

Final  

59.4bc 62.7ab 57.9c 63.5a 58.9c 0.82   64.8a 62.0b 60.7c 61.2b 61.4b 0.86   64.3 67.2 59.2 67.0 60.0 0.78

Initial  

25.8bc 27.2b 29.0a 27.8ab 24.1c 0.91   24.4 25.9 27.2 26.7 25.7 0.83   27.5 25.8 27.1 26.7 26.4 0.89

Middle  

31.7a 31.5a 30.9b 30.2b 29.3b 0.74   27.6b 31.3a 31.2a 31.9a 31.3a 0.82   33.0 30.9 32.8 33.3 30.5 0.71

Final  

32.3b 35.1a 31.4b 34.9a 32.4b 0.76   36.8a 33.8b 34.5b 33.7b 33.1b 0.78   36.0 37.2 36.4 38.6 36.8 0.74

Means within a column within year with different superscripts differ (P < 0.05). Initial = initiation of grazing period; middle = mid-point of grazing period; final = end of grazing period. 2 CW = AC Goliath crested wheatgrass; HB = AC Knowles hybrid bromegrass; SB = Carlton smooth bromegrass; MB = Paddock meadow bromegrass; TF = Courtenay endophyte-free tall fescue. a–c 1

growth, Ferdinandez and Coulman (2001) reported that HB had consistently lower NDF and ADF values than did either MB or SB, but there was no consistent trend as these species matured. Others have suggested that MB has marginally less forage nutritive value than does smooth bromegrass (Knowles et al., 1993), but this trend was less evident as the species matured. With advancing plant maturity, changes occur to the chemical composition of plant parts and within the sward structure of grass pastures, causing the nutritive value to decrease (Collins and Fritz, 2003). Kilcher and Troelsen (1973) showed that the decline in forage nutritive value with advancing maturity in smooth bromegrass resulted primarily from a decrease in the leaf:stem ratio, a decline in the CP concentration, and an increase in the cell wall lignin concentration of the whole plant. In addi-

tion, the leaf component maintained lower lignin content and greater CP, gross energy, and in vitro digestible energy content throughout the growing season compared with the stem component.

Animal Performance ADG. Steer-performance data for all years were analyzed separately because of a significant interaction (P = 0.05) between years for ADG, AGD, and BW gain per hectare (Table 4). Steer ADG was not different (P = 0.12) for all species in all 3 yr and ranged from 0.9 to 1.7 kg/d (Table 4). Steer BW gain was anticipated to be high for CW because this species is known for high nutritive value and reserves in the spring (Table 3; McKendrick and Sharp, 1970). Only TF produced less than 1.0 kg/d gain for most years, which may be related to reduced nutritive value and palatabil-

ity of this species later in the season. Performance of grazing animals is dependent on several factors, including forage nutritive value and intake, with forage intake influenced by forage nutritive value (Hart et al., 1983; NRC, 1996). Therefore, grazing perennial grasses in spring and early summer when forage nutritive value is greatest (Table 3) and intake is not limiting (data not shown) may result in better animal performance. The steer performance data in this experiment were similar to the results reported by Thompson et al. (2003). In an earlier experiment, Knowles et al. (1993) reported that BW gains of grazing cattle were similar between meadow bromegrass and smooth bromegrass during a June to August grazing period but were superior for meadow bromegrass during the August through October time period. More recent grazing experiments in Saskatchewan have also found similar

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Table 4. Steer performance and grazing capacity of perennial grass pastures1 Item ADG, kg  2005   2006  2007 Animal grazing days, AUD/ha2  2005   2006  2007 BW gain/ha, kg  2005   2006  2007

CW 1.7 1.3 1.3

HB 1.6 1.3 1.4

SB 1.2 1.1 1.3

MB 1.2 1.2 1.4

TF 1.3 0.9 0.9

SEM 0.39 0.16 0.22

215 215b 252b

242 269ab 320b

221 243b 288b

235 301a 320b

229 375a 344a

9.8 18.5 14.5

351a 316a 331b

250b 316a 394a

271b 212b 322b

281ab 340a 386ab

316a 329a 471a

40.9 40.7 22.4

Means within a row with different superscripts differ (P < 0.05). CW = AC Goliath crested wheatgrass; HB = AC Knowles hybrid bromegrass; SB = Carlton smooth bromegrass; MB = Paddock meadow bromegrass; TF = Courtenay endophyte-free tall fescue. 2 AUD = animal unit day, based on 1 animal unit (455 kg). a,b 1

ADG between smooth bromegrass, meadow bromegrass, and hybrid bromegrass during the summer grazing season (Thompson, 2003; Thompson et al., 2003). Average daily gains ranged from 0.53 to 1.25 kg, 0.78 to 1.36 kg, and 0.74 to 1.62 kg for smooth bromegrass, meadow bromegrass, and hybrid bromegrass, respectively (Thompson et al., 2003). Reuter and Horn (2002), in an experiment at Marshall, Oklahoma, evaluated 3 cool-season perennial grasses and reported that ADG of heifers and steers grazing smooth bromegrass pastures were 0.80 and 0.98 kg/d, respectively. Differences in steer BW gain between this experiment and other research may be a result of differences in forage nutritive value, environment, or animal grazing characteristics (Horn et al., 1979). Additionally, a short grazing period combined with high forage nutritive value may have attributed to the great ADG observed in this experiment. However, based on the forage yield and nutritive-value data presented in Tables 2 and 3, it could be assumed that all pasture species involved in the experiment provided similar levels of nutrition and available forage, which may explain similar animal gains among grasses. AGD. In yr 1, AGD for all grasses were not different (P = 0.10). Total

AGD in yr 2 was not different (P = 0.08) for CW, HB, and SB; however, MB and TF produced 24 and 55% greater (P = 0.03) AGD compared with the other grasses. In yr 3, only TF had greater (P = 0.05) AGD than CW, HB, SB, and MB paddocks. In yr 2 and yr 3, TF produced more grazing days per hectare (P = 0.02) compared with the other grasses. Total-3-yr AGD for TF was 26 and 39% greater than for SB and CW, respectively. When describing tall fescue, Balasko (1986) stated that much of the increase of tall-fescue pasture area in recent years has been related to its ability to provide more grazing days per year than other tallgrowing cool-season grasses. Balasko (1986) also indicated that tall fescue may be well suited to spring, autumn, and winter grazing because a lack of palatability may limit its use for summer pasture. Because Courtenay TF is an endophyte-free tall-fescue variety, it is possible the species lacks some drought and heat tolerance compared with varieties that contain endophytes, as endophytes typically improve plant persistence, heat, and drought tolerance (Hoveland et al., 1997). Despite lower AGD on the CW paddocks in this experiment, Cohen et al. (2004) demonstrated that it is possible to obtain much greater AGD

on crested wheatgrass when it is heavily fertilized (>100 kg of N/ha). In a long-term grazing experiment evaluating the effects of N fertilizer on performance of pregnant yearling heifers at Lanigan, Saskatchewan, ADG ranged from 0.34 to 1.23 kg/d, whereas AGD ranged from 92 to 499 AUD/ha with greater AGD typically the result of timely precipitation and high N fertilization (Cohen et al., 2004). In this experiment, it appears that CW with moderate fertility (79 kg of N/ha, 23 kg of P/ha) and good moisture conditions early in the year has similar or greater AGD compared with the rhizomatous, sod-forming stand of smooth bromegrass. BW Gain per Hectare. In all years, BW gain per hectare was different (P = 0.05) between cool-season grass types (Table 4). Total BW gain per hectare in yr 1 was greater (P = 0.05) for CW and TF than gain per hectare from the 3 bromegrasses. Steers grazing the CW paddocks in yr 1 produced almost 41% as much BW gain per hectare as steers grazing the HB paddocks. In yr 2, CW, HB, MB, and TF produced greater BW gain per hectare compared with SB pastures (P = 0.04). For the grazing seasons of yr 2 and yr 3, MB and SB produced a BW gain of 340 and 212 kg/ha and 386

410 and 322 kg/ha, respectively (P = 0.05). Knowles et al. (1993), at Melfort, Saskatchewan, reported higher BW gain per hectare for meadow bromegrass and smooth bromegrass pastures, 458 and 404 kg/ha, respectively. In a more recent grazing experiment in Saskatchewan, Thompson et al. (2003) reported AGD and BW gain per hectare to be similar (P > 0.05) among hybrid, meadow, and smooth bromegrass species. Animal grazing days and BW gain per hectare values for this experiment are greater than those reported by Thompson et al. (2003) but not as great as those reported by Knowles et al. (1993). Differing results between the 3 experiments may be a consequence of differences in environmental conditions before and during the grazing season, as well as differences in grazing period length and stand age. Body weight gain per hectare for CW, HB, TF, and MB paddocks was not different (P = 0.11) in yr 2. Tall fescue produced the greatest BW gain per hectare because of the high number of grazing days (329 and 471 AUD/ha) and a moderate ADG (0.9 kg/d) in yr 2 and 3. In a 3-yr grazing experiment evaluating endophyteinfected and endophyte-free tall fescue in central Georgia, Hoveland et al. (1997) reported BW production per hectare to be 99 and 285 kg/ha and 124 and 159 kg/ha for spring and autumn grazing periods, respectively. In 1 yr of the experiment they were not able to obtain an autumn (second) grazing period similar to this experiment. In a put-and-take grazing system, such as the grazing management used in this experiment, it is often difficult to determine a stocking rate (steers/ ha) that will be similar for the entire grazing period. However, a measure such as AGD will provide insight as to the carrying capacity of the pasture. For all experimental grasses over the 3-yr experiment, stocking rates varied from 5 steers/ha for CW paddocks to 17.5 steers/ha for TF paddocks. The combined AGD for all steers was 215 and 375 AUD/ha for CW and TF paddocks, respectively.

Lardner et al.

With the greater stocking rate for TF paddocks, overall individual animal gain was decreased compared with the lower stocking rates observed for the CW paddocks. However, overall BW gain per hectare in TF paddocks was similar or greater (yr 3) than in CW paddocks (Jones and Sandland, 1974). In a similar experiment evaluating steer performance grazing meadow foxtail (Alopecurus pratensis L.) and timothy (Phleum pratense L.), Rode and Pringle (1986) reported that although timothy had lower AGD than did meadow foxtail, timothy pastures had 28% greater BW gain per hectare because of greater individual gains. Similarly, Jones and Sandland’s (1974) model suggests that individual gain may be sacrificed at greater stocking rates, but the potential exists to maximize overall animal gain with an optimum stocking rate. Therefore, in reference to the Jones and Sandland (1974) model, it is likely that the grasses in this experiment would be consistent with the linear relationship between individual animal gain and stocking rate as well as the quadratic relationship between gain per hectare and stocking rate.

Economic Comparison Revenue, expense, and profit from each of the grass pasture types are shown in Table 5. Every year, CW, HB, MB, and TF grazing systems showed positive profit ($3.46 to $210.74/ha). Net return or profit was greatest for the TF grazing system in yr 3 of the experiment at $210.74. Profit was also high for MB pasture in yr 3 of the experiment, generating $123.75/ha. Only one grazing systems, SB in yr 2, showed a loss of −$24.64/ha. Calculated return for selling barley grain showed 1 yr of net losses (−$178.96/ha; yr 1) and 2 yr of positive net returns ($155.77/ha, yr 2; $76.37/ha, yr 3; Table 5). From 2005 to 2007, the average grain yield for growing barley at Lanigan, Saskatchewan, is reported to be 3,368 kg/ha (SMA, 2008b). The average price per bushel for barley during that period was $0.075/kg, which would generate

a revenue of $252.60/ha. However, average variable costs for growing an annual crop in the current 3-yr experiment were almost twice the costs for managing perennial pastures, averaging $236.66/ha for barley (Table 5). Similarly, fixed costs were also greater to grow an annual crop, averaging $150.47/ha for barley. This resulted in average total costs of $388/ha, which was 67% greater than average total costs for the pasture grazing systems ($233/ha). Average total expense was $233/ ha, to generate average revenues of $285/ha for all grazing systems over 3 yr. However, average total expenses to grow barley grain was $388/ha, to generate average revenues of $405/ ha. The potential to generate revenue was not as great in the pasture-based stocker grazing system as growing an annual crop, but neither was the yearly cash outlay (variable costs) or financial risk. When averaged over the 3-yr experiment, growing barley grain generated a profit of $18/ha. In comparison, profits from stocker grazing systems averaged over 3 yr for CW, HB, and TF were $89, $76, and $104/ha, respectively. These results suggest that a stocker system grazing TF can generate 6-fold profit compared with growing barley over the experiment. Another advantage to custom grassing stockers is that the system has the potential to provide a similar or more consistent revenue source when compared with annual cropping systems. When growing annual crops, weather can be a major factor in determining potential revenue. In the east-central Saskatchewan region, cool-season perennial grass pastures in good condition may better withstand prolonged heat and early or late frosts much better than annual crops such as barley. If there is less potential risk to the overall revenue of the forage-based system, and the total costs are lower, it would suggest that custom grazing stockers on new varieties of MB or TF may be economically advantageous. This experiment evaluated custom grazing of yearling steers to generate revenue from new cultivars of cool-

411

Stocker performance grazing cool-season perennial grasses

Table 5. Revenue, expenses, and profit from pasture systems compared with annual cropping ($/ha)1 Item

CW

2005  Revenue   Variable expenses   Fixed expenses   Total expenses  Profit2 2006  Revenue   Variable expenses   Fixed expenses   Total expenses  Profit2 2007  Revenue   Variable expenses   Fixed expenses   Total expenses  Profit2

 

HB

301.16 124.84 93.36 218.21 82.95   320.90 125.50 93.36 218.86 102.03   327.99 156.79 90.74 247.53 80.46

 

238.96 124.84 105.77 230.62 7.84   322.62 125.50 105.77 231.27 91.35   389.67 161.50 98.43 259.93 129.73

SB  

231.66 124.84 103.35 228.02 3.46   204.21 125.50 103.35 228.85 −24.64   319.18 159.09 98.43 257.51 61.66

MB  

240.24 124.84 104.23 229.08 11.17   306.74 125.50 104.23 229.73 77.01   382.14 159.96 98.43 258.39 123.75

TF  

270.70 124.84 101.78 226.62 44.08   281.85 125.50 101.78 227.28 54.58   466.69 157.51 98.43 255.94 210.74

BR  

199.06 229.55 148.47 378.03 −178.96   551.79 246.74 149.28 396.02 155.77   463.71 233.69 153.66 387.35 76.37

CW = AC Goliath crested wheatgrass; HB = AC Knowles hybrid bromegrass; SB = Carlton smooth bromegrass; MB = Paddock meadow bromegrass; TF = Courtenay endophyte-free tall fescue; BR = barley grain. 2 Return over total expenses. 1

season perennial grasses; however, the likelihood that producers will graze cow-calf pairs, supplement on pasture (Scaglia et al., 2009), or sod seed into existing pasture (Beck et al., 2011) is just as great. In a recent 6-yr experiment evaluating the economics of converting from grain to grass production in northeast Saskatchewan, rotational grazing of perennial pastures (meadow bromegrass–alfalfa) by cow-calf pairs provided greater net return ($57.94/ ha) compared with annual cropping systems ($28.80/ha; Lang, 2006b). Thus, the results from this experiment are similar to those reported by Lang (2006b). Finally, grazing perennial cool-season grass pastures can provide comparable, if not greater, net returns compared with an annual cropping system.

IMPLICATIONS In this 3-yr experiment, crested wheatgrass was greater in first-year and total forage biomass than the other grasses. Tall fescue, CW, and HB had higher CP early in the grazing period than did MB forage. No

consistent difference was observed in growth performance of steers grazing cool-season grass pastures. However, TF and HB had greater total animal grazing days compared with the other grass species. Greatest BW gain per hectare was observed from steers grazing TF, CW, and MB totaled over the 3-yr experiment. Total expenses to manage a cool-season pasture program were 41% lower compared with growing an annual crop. The management decision to graze TF pastures with stocker cattle showed consistent profit averaging $104/ha over 3 yr. This would suggest that grazing this cool-season grass with stocker cattle can generate similar if not greater profit compared with growing barley over the long term. Decisions concerning which perennial grass variety to use in stocker programs can be used to manage risk and profit over time.

opment Fund. The authors also thank Leah Pearce and George Widdifield at the Termuende Research Ranch and numerous staff at the University of Saskatchewan for assisting in data collection and laboratory analysis.

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