Yield, herbage composition, and tillering of timothy cultivars under grazing H. T. Kunelius1, G. H. Dürr1, K. B. McRae2, S. A. E. Fillmore2, G. Bélanger3, and Y. A. Papadopoulos1 1Crops and Livestock Research Centre, Agriculture and Agri-Food Canada, 440 University Avenue, Charlottetown, Prince Edward Island, Canada C1A 4N6, (e-mail:
[email protected]); 2Atlantic Food and Horticulture Research Centre, Agriculture and Agri-Food Canada, Kentville, Nova Scotia, Canada B4N 1J5, 3Soils and Crops Research and Development Centre, 2560 Hochelaga Boulevard, Sainte-Foy, Québec, Canada G1V 2J3 . Contribution no. 977, received 2 October 2001, accepted 10 July 2002.
Kunelius H. T., Dürr, G. H., McRae, K. B., Fillmore, S. A. E., Bélanger, G. and Papadopoulos, Y. A. 2003. Yield, herbage composition, and tillering of timothy cultivars under grazing. Can. J. Plant Sci. 83: 57–63. Timothy is widely grown for silage and hay in eastern Canada. The relative performance of timothy cultivars under grazing is not, however, well documented. This research determined dry matter production, herbage composition, and tiller characteristics of 34 timothy cultivars under two grazing schedules over 3 yr on the same plots. Several cultivars outyielded the standard cultivar, Farol (7.96 t ha–1), by up to 10% for the 3-yr mean. Richmond and Comtal were the highest-yielding cultivars (8.75 t ha–1) while AC Regal had the best relative yield persistence over the experimental period. Crude protein concentrations of cultivars ranged from 172 to 208 g kg-1 for early and 150 to 179 g kg–1 for late grazing. Neutral detergent fibre (NDF) concentrations ranged from 460 to 495 g kg–1 and concentration of acid detergent fibre (ADF) ranged from 241 to 270 g kg–1 among the cultivars in early grazing. Differences in NDF and ADF concentrations between early and late grazing schedules varied among the cultivars indicating a variable rate of change in fibre concentration. Farol, Timora, Promesse, and Comtal had greater tiller densities than most other cultivars while AC Alliance, Colt, and Winmor had below average tiller densities throughout the grazing season. The ratio between reproductive and vegetative tillers was higher early in the season, than later, but depended on the grazing schedule. The reproductive to vegetative tiller ratios covered a wide range in the third (2–54) and fourth (3–115) grazing periods. We conclude that yield and relative yield persistence of timothy cultivars under grazing varied greatly among cultivars. Tillering density of cultivars also varied but was not significantly related to cultivar performance under grazing. Key words: Timothy, Phleum pratense, grazing, composition, tiller Kunelius, H. T., Dürr, G. H., McRae, K. B., Fillmore, S. A. E., Bélanger, G. et Papadopoulos, Y. A. 2003. Rendement, composition des herbages et tallage des cultivars de fléole servant à la paissance. Can. J. Plant Sci. 83: 57–63. On cultive beaucoup la fléole pour la production de foin et d’ensilage dans l’est du Canada. Néanmoins, on ne connaît pas grand-chose du rendement des différents cultivars destinés à la paissance. Trois années durant, les chercheurs ont étudié la production de matière sèche, la composition des herbages et les caractéristiques de tallage de 34 cultivars de fléole sur des parcelles identiques, dans le cadre de deux régimes de paissance. Plusieurs variétés avaient un rendement supérieur à celui de Favol (7,96 tonnes par hectare), le cultivar servant d’étalon. L’écart a atteint jusqu’à 10 % pour la moyenne triennale. Richmond et Comtal étaient les cultivars les plus productifs (8,75 tonnes par hectare), mais AC Regal a présenté le rendement le plus stable pour la durée de l’expérience. La concentration de protéines brutes variait de 172 à 208 g par kilo avec une mise à l’herbe hâtive et de 150 à 179 g par kilo avec une mise à l’herbe tardive. Avec le régime de paissance hâtive, la concentration de fibres au détergent neutre (FDN) fluctuait de 460 à 495 g par kilo et celle de fibres au détergent acide (FDA) de 241 à 270 g par kilo. La variation de la quantité de FDN et de FDA entre les deux régimes de paissance fluctue d’un cultivar à l’autre, signe que la concentration de fibres évolue différemment dans le temps. Les talles de Farol, de Timora, de Promesse et de Comtal étaient plus denses que ceux de la plupart des autres cultivars; d’autre part, AC Alliance, Colt et Winmor ont présenté des talles d’une densité inférieure à la normale toute la saison. Le rapport entre le nombre de talles reproducteurs et végétatifs est plus élevé au début de la saison, mais il varie avec le régime de paissance. Ce rapport fluctue considérablement au cours de la troisième (2–54) et de la quatrième (3–115) période de mise à l’herbe. Les auteurs en concluent que le rendement et la stabilité relative de ce dernier varient considérablement avec le cultivar. La densité du tallage fluctue aussi, mais elle ne présente pas de corrélation significative avec le rendement des cultivars en régime de paissance. Mots clés: Fléole, Phleum pratense, paissance, composition, talle
Timothy (Phleum pratense L.) is the most widely grown perennial forage grass species in eastern Canada. It is well adapted to the prevalent cool and moist climate and provides high dry matter yields of quality forage under these conditions (Kunelius 1990; McElroy and Kunelius 1995). Grown principally for hay and silage in livestock operations and short-term crop rotations, regrowth is often grazed in the summer and fall.
Timothy in pasture provides a palatable, low-cost feed for cattle during the growing season. Animal performance on timothy pasture is usually equal to or better than that on other temperate grasses (Alder 1970; Davies and Morgan Abbreviations: ADF, acid detergent fibre; CP, crude protein; DM, dry matter; NDF, neutral detergent fibre 57
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1982; Rode and Pringle 1986; Maunsell and Scott 1996). Milk solids production by cows has been found to be greater on timothy pasture than on either perennial ryegrass (Lolium perenne L.) or orchardgrass (Dactylis glomerata L.) (Johnson and Thomson 1996). Because timothy grows upright with the stem apices raised, it is suspected to lack tolerance to frequent defoliation under grazing (Nesheim and Karlsen 1988; Kunelius and Narasimhalu 1993). Furthermore, knowledge concerning grazing management, developed for other grass species, may not be valid for timothy pastures (Virkajärvi and Järvenranta 2001). The effect of grazing animals on timothy cultivars is not well understood because cultivars are usually developed and evaluated under mechanical defoliation. Large differences in groundcover, available forage, and apparent intake among timothy cultivars rotationally grazed by dairy cows have been reported (Casler et al. 1998). Some evidence suggests that animal performance on pasture can be improved through small but consistent improvements in the nutritional quality of grasses (Westwood and Norriss 1999). Although timothy is sown in pastures, relatively little attention has been paid to developing timothy cultivars for grazing purposes, particularly under Maritime conditions (Berg et al. 1996; Caradus 1988; Stevens et al. 1993; Kunelius et al. 2001). In New Zealand, Caradus (1988), Stevens et al. (1993), and Maunsell and Scott (1996) reported on grazing studies with timothy cultivars, including Kahu, which was developed for pasture use. Other timothy cultivars in our study were also developed for use in pasture or as conserved forage, but their performance under grazing is not well documented. Timothy cultivars may differ in their ability to adjust tiller density and size to maintain sward productivity (Kunelius et al. 2001). In contrast to other grasses, such as meadow fescue (Festuca pratensis Huds.), timothy sward is characterized by a predominance of reproductive tillers (Bélanger and Richards 1997). Hence, the study of the relationship between tiller density and size should take into account both vegetative and reproductive tillers. Such information, in turn, should lead to the definition of selection criteria, which could be used to develop timothy cultivars adapted to grazing. This study aimed to determine DM production, composition and sward characteristics of timothy cultivars under two grazing schedules. MATERIALS AND METHODS The experiment was conducted at Charlottetown, Prince Edward Island, Canada (Lat/Long: 46.2/63.1 and 23 m above sea level) under temperate, moist conditions with occasional periods of summer drought (Table 1). The soil was a fine sandy loam, an Orthic Humo-Ferric Podzol with a pH of 6.6. Before seeding, the experimental site was fertilized with 50 kg N ha–1. Timothy cultivars were sown at 12 kg ha–1 on 26 August 1994. The timothy plots (1.5 × 20 m) were sprayed with MCPA at 420 g a.i. ha–1 and dicamba at 105 g a.i. ha–1 on 15 May 1995 to control broadleaf weeds. In the production years (1995-1997), ammonium nitrate was applied at 50 kg N ha–1 in early May and after the first grazing period; also at 40 kg N ha–1 after the second and third grazing periods. Timothy plots also received P (20–30 kg
ha–1) and K (50–90 kg ha–1) based on soil test recommendations in the seeding and production years. Intervals between grazing events and sward height at the start of grazing appear in Table 2. At the first grazing, timothy cultivars under the early schedule were at the vegetative stage of development. Timothy cultivars under the late schedule were grazed 7 d later than under the early schedule. Pregrazing sward and post-grazing stubble heights were measured with a sward stick (Barthram 1986) in five randomly selected areas on each plot. All timothy plots in each main plot were grazed simultaneously by crossbred yearling steers of various genetic backgrounds. Stocking rates were adjusted to achieve within 2 d an average post-grazing height of 9 cm for the cultivars. The plots were grazed four times in year 1 (1995), year 2, and year 3, except for the late grazing system in year 3 which was grazed three times due to poor growth of timothy. The third grazing in year 2 was eliminated from the data set (and marked as missing values) after cattle broke into a paddock before sampling. Before each grazing period, a randomly selected 20 × 20 cm area on each plot was clipped at soil surface. The timothy herbage was separated into reproductive (seed head showing or exhibiting stem elongation) and vegetative tillers; tillers were counted and weighed after drying at 85°C for 48 h. Ground cover by timothy on each plot was rated visually before the first grazing period. Herbage biomass before grazing was determined from a 1.5 × 3 m area of plot harvested with a Haldrup forage plot harvester (J. Haldrup, Løgstor, Denmark) at 9-cm stubble height. At each grazing, yield was determined from an area of plot that had been grazed, but not clipped for yield during the season. After the first grazing, the plots were clipped to a uniform height of 9 cm. After subsequent grazings during the season, clipping was not needed because post-grazing stubble heights among the cultivars were similar (8.9 range ± 1.2 cm). Samples (350 g) of chopped (2–4 cm long) fresh herbage were collected from each plot, freeze-dried, and DM determined. The dried samples were ground to pass a 1-mm screen for determining composition of herbage. Nitrogen was determined by combustion with the LECO-CNS-1000 analyzer (LECO Instruments Ltd., Mississauga, ON) and elemental N was multiplied by 6.25 to obtain crude protein (CP). Mineral composition (Ca, Mg, Na, P, K, Cu, Zn, Mn, Fe, B, S) was analyzed by inductively coupled argon-plasma spectrometry after dry ashing and extraction with dilute HCl (Thermo Jarrell Ash Corp. 1100, Waltham, MA). Neutral detergent fibre (NDF) and acid detergent fibre (ADF) concentrations were determined with ANKOM Fiber Analyzer F 200 (ANKOM Technology Corp., Fairport, NY) based on the method of Van Soest (1982). The experiment was set out in a split-plot design structure with two grazing schedules randomized to the four replicates (two replicates each), but the 34 timothy cultivars (Table 4) were randomized according to a generalized lattice (alpha series) to six blocks of five plots, and one block of four plots (Genstat 5 Committee 1993). Analyses were performed with replicates, blocks, and plots treated as ran-
KUNELIUS — YIELD, HERBAGE COMPOSITION, AND TILLERING OF TIMOTHY CULTIVARS UNDER GRAZING Table 1. Mean monthly temperatures and total monthly precipitation during the three grazing seasons in Charlottetown, Prince Edward Island, Canada Temperature (°C) Month
Year 1
May 7.4 June 14.6 July 19.6 August 17.7 September 12.3 October 10.2
Precipitation (mm)
Year 2
Year 3
Mean 80 yr
Year 1
Year 2
Year 3
Mean 80 yr
8.3 15.5 18.1 19.0 14.0 7.4
8.6 13.8 19.0 17.7 14.8 7.2
9.2 14.8 18.8 18.4 14.0 8.6
100 122 68 75 71 82
109 81 163 12 106 119
91 87 26 75 81 36
94 87 78 90 92 112
dom effects in the models while grazing schedules and cultivars of timothy were fixed effects (Table 3). When years were included in a multiple-year ANOVA, years (and its interaction with fixed effects) were taken to be random effects. Pair-wise correlations among the cultivar means from the ANOVA and residual maximum likelihood (REML) analyses were calculated. Some measurements were repeated on the same plot for each grazing over the three growing seasons. The methods used to bring these repeated measures into summary variates depended on the variate and whether spatial variation had to be taken into account (Snedecor and Cochran 1980 pp 330–332). Seasonal DM yields were calculated for each year and the 3-yr mean; these were analyzed by REML to account for the spatial variation among the blocks following the generalized lattice design for cultivars (Table 4). Similar variates that did not have significant spatial variation among blocks were analyzed by ANOVA according to the split-plot design. These included yield persistence and the visual groundcover assessment taken in May of year 3. Tiller samples were taken and separated into vegetative and reproductive tillers before most grazings over the 3 yr, but there were gaps in the sampling plan. Samples were taken in different areas each time, and were not repeated measurements on the same plants; tiller data for the four grazings were analyzed with a multiple year model (Table 3). Crude protein, NDF, and ADF were analyzed similarly (Tables 5 and 6). Missing values were estimated according to the additive model in the ANOVA or REML algorithms in Genstat 5 (Genstat 5 Committee 1993) with a corresponding reduction in the error degrees of freedom. Some of the variates required transformations to meet the assumptions for ANOVA. Relative yield persistence of the ith cultivar was defined by LOG10(Ri /Rstd), where the ratio of the third to the first seasonal yield for the ith cultivar is denoted by Ri and for the standard cultivar, Farol, by Rstd. The means were back transformed to the percentage scale for presentation (Table 4). Tiller density consists of count data and were analyzed as √X; the means and standard errors were back transformed to the arithmetic scale for presentation in Table 6. Ground cover, expressed as percentage data, did not require transformation because the range of its values is limited. To assist in displaying the variation among the timothy cultivars under grazing, we used the LSD range centred on the grand mean to differentiate between the extreme groups
59
Table 2. Average grazing interval and pre-grazing sward height of timothy cultivars for two grazing schedules Grazing interval (d)
Sward height (cm)
Grazing
Earlyz
Late
Early
Late
First Second Third Fourth
34y 26 31 52
41 33 36 36
29 31 26 16
37 27 27 17
zGrazing schedule. yDays from 1 May,
start of growing season.
of cultivars. In Tables 4–6, values for the cultivars in the “high” group are in bold type and those in the “low” group are underlined. All the bolded values are significantly different from the underlined values, according to the LSD procedure at the 5% level. There will be more LSD significant differences (some extremes in each group will differ with some of the intermediate values), but the simplified display aids in conveying the diversity of timothy cultivar responses under grazing. Statistical tests were performed at (P = 0.05) except where noted otherwise. The rows in Tables 4–6 are ordered according to the values of the 3-yr DM yield to assist in conveying relationships between variates, or their lack of a strong correlation. RESULTS The DM yields of cultivars were significantly different in each year and for the 3-yr mean (Table 4). In year 1, DM yields of cultivars ranged from 7.20 to 9.36 t ha–1, in year 2 from 5.83 to 7.54 t ha–1, and in year 3 from 8.11 to 10.52 t ha–1. Rainfall from late July to mid-September in year 2 was low, reducing the growth rate of timothy (Table 1). Comtal had the highest DM yields among the cultivars in year 1 and 2. Basho, AC Regal, Promesse, and Richmond were the highest-yielding cultivars in year 3 and greater than AC Alliance, Carola, Nike, Alexander, Mariposa, and Toro. Cultivar Farol, a commonly grown pasture timothy in Atlantic Canada, was used as a standard. For the 3-yr mean, eight cultivars had yields ranging from 8.43 to 8.75 t ha–1 , which was at least 0.5 t ha–1 more than that for seven other cultivars with less than 7.93 t ha–1; yield for Farol was 7.96 t ha–1. Richmond and Comtal were the highest-yielding (8.75 t ha–1) cultivars, but Itasca, Kahu, SF8602, Salvo, AC Antoine, and Promesse also outyielded the standard cultivar, Farol, by 0.4 to 0.7 t ha-1. Several of the cultivars recommended in 2001 for Atlantic Canada had DM yields similar to Farol, except Richmond and Itasca, which yielded more than Farol. The DM yields of AC Alliance were lowest among the recommended cultivars. The 3-yr mean DM yields were greater (P < 0.01) for the early than late grazing system. The yield difference was greatest in the third year when there were three, instead of four, grazings for the late system. The difference in seasonal yield between the early and late grazing schedules was smallest in year 2. The persistence of yield for cultivars over several production years is important in pasture production. Yield persistence was correlated with year 3 DM yield, but both variates lacked the precision to differentiate cultivars clear-
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Table 3. Analysis of variance partitioning of degrees of freedom (df) for single year and multiple year models Single year model Source of variation Grazing schedule (GS) Rep within GS Cultivar Cultivar × GS Residual
Multiple year model df 1 2 33 33 66z
Source of variation
df
Year Grazing schedule (GS) Reps within GS and Year Cultivar Year × Cultivar GS × Cultivar Residual
2 1 8 33 66 33 264
zIn the REML analysis for DM yield, the spatial variation was partitioned into
24 df among blocks within replicates and 42 df among plots within blocks.
ly (Table 4). Cultivars Basho and AC Regal had greater yield persistence than Nike, Alexander, Mariposa, and Toro despite similar 3-yr DM yields. The eight cultivars with “high” 3-yr DM yield and AC Regal had yield persistence values that were not significantly different. There was some evidence that the late grazing adversely affected yield persistence (early 5% versus –20% for late grazing, SE = 11.8). Ground cover by timothy in year 3 was highest at 92% for Motim and lowest at 65% for Winmor. Ground cover was significantly correlated with only vegetative tillers; pairwise correlation coefficients were 0.33, 0.45 and 0.70 for grazings 1, 2, and 4, respectively. Post-grazing stubble heights were similar, averaging 8.9 (range ± 1.2 cm) for all cultivars and grazings. Crude protein concentrations depended on grazing schedule and cultivars and ranged from a low of 172 g kg–1 for Toro to a high of 208 g kg–1 for Tika in early grazing, and a low of 150 g kg–1 for Goliath to 179 g kg–1 for Climax in late grazing (Table 5). Three cultivars (SF8604, Tika, and Normax) had high CP values for both grazing schedules, while Tiller, Goliath, Toro, and Salvo had low values for both. Champ had high CP for the early grazing and low CP for the late grazing, while AC Regal had the opposite. Other cultivars differed to a lesser degree. Crude protein concentrations averaged 193 g kg–1 for the early grazing system and 162 g kg–1 for the late system (P < 0.001). There were small but significant (P < 0.001) differences (not tabulated) among the cultivars in concentrations of P (3.4–3.7 g kg–1), K (26–29 g kg–1), Ca (2.9–3.7 g kg–1), Mg (1.5–1.7 g kg–1), B (5.7–7.5 mg kg–1), Cu (5.6–6.6 mg kg–1), S (2.3–2.6 mg kg–1), and Zn (23–29 mg kg–1) but the range was greater for Mn (39–58 mg kg–1). The NDF concentration of cultivars for the early grazing system ranged from 460 to 495 g kg–1 and from 493 to 527 g kg–1 for the late grazing (Table 5). The grazing schedule × cultivar interaction was significant at (P = 0.065) due to cultivar differences (11 to 51 g kg–1) between early and late grazing schedules. For example, the difference for the early-maturing cultivar Tiller was 46 g kg–1, while the difference for Salvo, also an early-maturating cultivar, was 11 g kg–1. For the late grazing, AC Alliance was lowest in NDF and Tiller was highest. Concentrations of ADF among the cultivars ranged from 241 to 270 g kg–1 for the early-grazing system (Table 5). In late grazing, the ADF concentration of cultivars ranged from
261 to 288 g kg–1. The difference in ADF concentration between early and late grazing schedules averaged 19 g kg–1 and interaction with cultivars was not significant. AC Alliance had the lowest ADF while Tiller was highest in ADF (251 vs. 276 g kg–1). Both NDF and ADF for the early grazing were positively correlated (r > 0.61) with DM yield in year 1, year 2, and the 3-yr mean. Also, all pair-wise correlations between NDF and ADF and the two grazings were significant. Tiller densities depended on the grazing schedule, the grazing event, and the cultivar (Table 6). Both the vegetative and reproductive tiller densities were highly variable due, in part, to the limited sample size. We can only discern general trends. The grazing schedule affected the number and type of tiller on the first grazing; 2000 and 800 vegetative tillers m–2 in the first grazing for the early and late grazing schedules, respectively, but accompanied by 600 and 1600 reproductive tillers m–2. The numbers were more consistent for later grazings. Tika, Carola, Farol, Goliath,Tuukka, Timora, Promesse, and Comtal had higher vegetative tiller densities than AC Alliance and Winmor. Cultivars with the highest reproductive tiller densities included Farol, Nike, Mariposa, Toro, and AC Regal, while Tika, Pick81009, Tuukka, Motim, Promesse, and Comtal had low reproductive tiller densities in most grazings. The ratio between reproductive and vegetative tillers was greater at the first grazing, with 15–74% of the tillers being reproductive. Early-maturing cultivars, such as Tiller and Richmond, had the greatest ratio while the late-maturing Motim had the lowest ratio. At the third and fourth grazings, the proportion of reproductive tillers decreased, but there were large differences among cultivars (0 to 28% reproductive). Comtal, Tuukka, Timora, Promesse, and Erecta had a low proportion of reproductive tillers in late summer, whereas AC Regal, AC Alliance, Basho, and Toro had high proportions. The DM weight per tiller was highest at first grazing and ranged from 87 to 172 mg tiller–1. In the second and third grazings, the tiller weights were 52 to 146 mg and 73 to 162 mg tiller–1, respectively. At the fourth grazing the tiller weight ranged from 19 mg tiller–1 for Farol to 164 mg tiller–1 for Toro. DISCUSSION Several cultivars yielded up to 10% more than Farol, the standard timothy cultivar, in the 3-yr mean. Richmond, an early-maturing cultivar, had consistently high yields every grazing season. In contrast, Comtal was the highest-yielding cultivar in year 1 and 2, but yield declined in year 3. Basho, Promesse, AC Regal, and Richmond had high yields in year 3. In the 3-yr mean, yield difference among the cultivars was up to 24%. Similar differences among timothy cultivars were also found in Atlantic Canada (Kunelius et al. 2001) and in Wisconsin (Casler et al. 1998) in pasture studies, but in New Zealand there were only small differences among 12 timothy cultivars (Maunsell and Scott 1996). Caradus (1988) concluded that Kahu was the most productive and persistent pasture cultivar of timothy under New Zealand conditions; it performed consistently well in these trials, and maintained good ground cover. Cultivars developed and
KUNELIUS — YIELD, HERBAGE COMPOSITION, AND TILLERING OF TIMOTHY CULTIVARS UNDER GRAZING Table 4. Seasonal DM yield, yield persistence, and groundcover of timothy cultivars under two grazing schedules Seasonal DM yield (t ha–1)
Yield Groundpersistencez covery (%)
Table 5. Crude protein, neutral detergent fibre (NDF) and acid detergent fibre (ADF) concentrations of timothy cultivars under two grazing schedules, averaged over all grazing periods Crude protein (g kg–1)
Cultivar
Yr 1
Yr 2
Yr 3
3-yr mean
AC Alliancex SF8604 Tika Pick81009 Carola Winmor Champx Farolx Tiller Nike Goliath Coltx Climaxx Alexander Drummondx Tuukka Timora Argus Basho Normax Motim Timfor Mariposa Erecta Toro AC Regal Itascax Kahu SF8602 Salvo AC Antoine Promesse Comtal Richmondx SEM (n = 4, 65 df) Early grazing Late grazing SEM (n = 68, 2 df) Mean
7.20w 7.49 8.07 7.77 7.86 7.85 8.35 8.19 8.42 8.82 8.29 8.08 8.30 9.08 7.91 8.64 8.14 8.68 8.19 8.54 8.46 8.43 8.85 8.58 9.09 7.94 8.54 8.61 8.64 9.23 8.50 8.54 9.36 9.14
6.01 6.37 6.07 5.83 6.47 6.60 6.25 6.44 6.63 6.99 6.33 6.46 6.63 6.53 6.92 6.43 6.64 6.55 6.26 6.92 7.03 7.14 7.09 6.79 7.34 6.96 7.13 7.12 7.24 7.18 7.08 6.81 7.54 6.94
8.11 8.85 8.90 9.33 8.7 9.18 9.14 9.56 9.02 8.17 9.27 9.78 9.17 8.50 9.36 9.38 9.86 9.49 10.15 9.33 9.44 9.40 8.27 9.74 8.37 10.52 9.36 9.74 9.66 9.32 9.89 10.41 9.59 10.48
7.03 7.60 7.65 7.67 7.79 7.87 7.92 7.96 7.99 8.04 8.08 8.09 8.10 8.11 8.12 8.16 8.17 8.18 8.18 8.23 8.26 8.27 8.28 8.30 8.34 8.36 8.43 8.49 8.53 8.61 8.63 8.66 8.75 8.75
–10 0 –8 –4 –7 –6 –13 0 –5 -25 –11 –2 –6 –26 1 –10 1 –9 5 –13 –5 –8 –20 –11 -24 7 –6 –7 –9 –17 –4 –1 –14 –6
71 72 81 69 69 65 78 89 75 71 84 67 68 76 73 83 71 76 75 70 92 74 75 78 74 70 74 79 69 76 76 80 73 71
0.402 8.01 8.8
0.368 6.96 6.5
0.451 11.59 7.09
0.214 8.86 7.47
8 5 –20
1.9 72 77
SEMy
0.244 8.41
0.275 6.73
0.614 9.34
0.176 8.16
3.8 75
SEM (2 df)
11.8 –8
(%)
zRelative
yield persistence is defined by LOG10(Ri/Rstd) where Ri is the ratio of yield in year 3 to year 1 for ith cultivar with Farol as standard (std). The ANOVA was performed on the LOG10 scale but the means are back-transformed to percentages for presentation. yGroundcover, visual estimate in May of year 3: 100 = full cover by timothy, 0 = no timothy left. xRecommended timothy cultivars in Atlantic Canada in 2001. win bold-faced type are significantly greater than those underlined in the same column, as judged by the LSD (5%) interval centred on the mean.
evaluated primarily for hay production such as Richmond and AC Regal performed very well over 3 yr when evaluated under grazing. Timothy cultivars differed significantly in nutrient composition although the range for minerals was generally small. There were, however, differences in crude protein concentrations of cultivars ranging from 172 to 208 g kg–1 for early grazing, and from 150 to 179 g kg–1 for late grazing. Brégard et al. (2000) attributed differences in forage N concentration of two populations of timothy to differences in the proportion
61
NDF (g kg–1)
ADF (g kg–1)
Cultivar
Early
Late
Early
Late
Early
Late
AC Alliance SF8604 Tika Pick81009 Carola Winmor Champ Farol Tiller Nike Goliath Colt Climax Alexander Drummond Tuukka Timora Basho Argus Normax Motim Timfor Mariposa Erecta Toro AC Regal Itasca Kahu SF8602 Salvo AC Antoine Promesse Comtal Richmond
191x
156 172 168 152 151 166 156 157 156 161 150 160 179 154 159 171 161 161 167 178 169 176 161 164 153 177 160 163 161 154 155 159 171 151
460 470 475 470 466 472 462 472 481 476 486 473 474 486 479 474 469 463 487 480 482 480 472 484 495 483 480 478 479 495 471 484 487 483
493 509 502 506 500 499 513 510 527 503 497 502 498 502 505 502 504 508 508 499 509 501 503 516 517 513 499 510 506 506 501 508 509 511
241 248 249 256 251 253 247 262 264 256 259 252 255 261 259 255 255 246 261 258 257 259 253 263 268 263 258 258 260 270 252 257 269 260
261 273 270 278 275 276 275 277 288 271 271 271 273 267 268 272 274 273 280 272 276 274 269 284 286 279 272 277 275 270 268 276 281 279
Mean
201 208 196 195 190 202 186 186 200 180 203 193 193 196 198 203 185 195 200 197 195 188 196 172 186 183 192 195 180 193 177 196 194 3.9 193
5.2 162
1.8
477
3.7 506
6.2
257
274 3.3
zCrude protein = seasonal mean total N × 6.25. yCrude protein ( n = 12, 193 df), NDF and ADF (n = 6, 129 df). xValues in bold-faced type are significantly greater than those underlined
in the same column, as judged by the LSD (5%) interval centred on the mean.
of leaves. The proportion of leaves was not measured in our study and we could not explain the cultivar differences in CP concentration by the proportion of reproductive tillers or the tiller size. In general, crude protein concentration of timothy cultivars in this study would be sufficient to meet the requirements of lactating cows. Delaby et al. (1996) reported that cows grazing swards with crude protein concentrations greater than 160 g kg–1, had a low milk-production response to supplementary metabolizable protein. There were differences in the fibre concentration of cultivars, with AC Alliance being low both in ADF and NDF. Differences in ADF and NDF concentrations among the cultivars exceeded 30 g kg–1, which could affect animal performance. Differences in NDF and ADF concentrations were reported among half-sib-families and among popula-
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Table 6. Density of vegetative and reproductive tillers, and DM weight of tillers for timothy cultivars at four grazing periods Reproductive tillers (×100 m–2) Cultivar/grazing AC Alliance SF8604 Tika Pick81009 Carola Winmor Champ Farol Tiller Nike Goliath Colt Climax Alexander Drummond Tuukka Timora Basho Argus Normax Motim Timfor Mariposa Erecta Toro AC Regal Itasca Kahu SF8602 Salvo AC Antoine Promesse Comtal Richmond SEM (n = 24,y df) Early grazing Late grazing SEM (n = 408 8df) Mean
1
2
6 5 7 5 15 4 10 12 16 14 11 8 13 13 6 11 10 16 10 9 4 9 19 11 20 13 8 11 5 14 9 12 12 20 0.8 6 16 0.3 11
9 12 11 9 10 11 10 16 9 7 10 6 8 7 9 7 8 9 8 7 9 9 10 7 7 12 6 9 10 7 11 7 7 7 0.7 9 9 0.8 9
3 0.8 0.5 0.3 0.3 0.5 1.2 1.1 1.4 1.3 1.6 0.8 0.7 0.7 1.7 0.8 0.3 1.0 0.7 3.1 1.4 0.3 0.9 1.5 0.7 2.4 2.2 1.1 1.0 0.5 0.7 1.1 0.4 0.5 1.8 0.14 1.8 0.4 0.11 1.0
Vegetative tiller (×100 m–2)
4 2.2 2.9 0.2 1.1 2 1.7 3.4 6 2.5 2.9 0.7 1.4 0.7 2.3 0.8 0 0.4 3.1 2.0 2.8 0.2 1.7 2.6 0.5 2.7 4.0 2.3 1.8 3.2 1.4 2.9 0.6 0.2 2.0 0.24 1.5 1.9 0.13 1.8
1
2
3
10z 17 22 17 10 16 13 14 5 9 12 8 15 12 15 16 22 12 15 14 23 12 10 20 11 11 13 13 16 14 11 16 13 7 0.9 20 8 0.6 14
11 17 22 16 17 11 14 24 11 12 20 12 15 14 13 19 22 14 15 12 13 13 15 17 15 14 11 17 13 13 15 18 21 15 0.8 12 16 0.7 15
7 8 12 10 12 9 10 15 10 10 15 5 6 8 9 12 18 7 5 15 6 7 10 14 9 8 12 10 9 10 11 21 17 13 0.6 12 8 0.6 10
Tiller DM (mg) 4 6 11 13 8 16 7 13 17 11 9 15 7 7 11 14 16 16 9 20 11 23 11 12 14 8 10 10 16 10 15 10 14 17 9 1 14 10 0.3 12
1 172 107 97 130 135 160 126 87 168 145 160 165 150 137 130 122 115 132 125 124 100 162 155 97 127 132 135 111 132 153 142 118 124 162 12.3 107 160 12.3 134
2
zValues in bold-faced type are significantly greater than those underlined in the same column, as judged by the LSD (5%) interval yDegrees of freedom equal 127, 172, 99, and 87 for grazing 1, 2, 3, and 4; calculated over years and adjusted for missing values.
tions of timothy following one cycle of divergent selection (Surprenant et al. 1990a, b; Brégard et al. 2001). Cultivars also differed in their ability to maintain consistent fibre concentrations between early and late grazing schedules. Genetic variation in the decline of digestibility with advance in maturity has been reported in timothy (McElroy and Christie 1986). Salvo had similar fibre concentrations for both grazing schedules, while Tiller had the greatest increase in fibre between grazing schedules. Tiller density varied considerably among the cultivars. In general, tiller density of timothy cultivars was low in comparison to perennial ryegrass, a grass species not well adapted to cold-winter regions. The tiller densities in our study were similar to those reported by Bélanger (1996) and Kunelius et al. (2001) in Atlantic Canada. Several cultivars including Tika, Farol, Goliath, Tuuka, Timora, Promesse, and Comtal had consistently high vegetative tiller densities throughout the grazing season. Cultivars AC Alliance and Climax, both recommended in Atlantic Canada, had lower tiller densities than Farol timothy. Bélanger (1996) also
3
78 84 75 76 70 146 61 76 80 65 52 70 78 64 79 68 65 68 96 96 87 79 89 78 60 96 59 77 104 73 75 62 63 69 10.1 75 79 5.3 77
92 70 92 73 88 93 77 80 78 80 82 162 78 105 85 80 75 115 75 100 97 112 92 117 137 87 102 75 82 105 78 78 70 110 9.7 87 98 5.9 92
4 124 96 44 99 64 114 72 19 92 84 54 109 116 84 71 41 44 109 46 81 40 79 104 71 164 91 86 39 124 60 74 40 59 106 11.9 75 85 7 80
centred on the mean.
reported that the early-maturing cultivars, Clair and Axel, had a lower tiller density than the late-maturing cultivar Farol. Cultivars Farol, Nike, Mariposa, Toro, and AC Regal consistently had high reproductive tiller densities throughout the growing season. For the cultivars in the “high” 3-yr DM yield group, it appears that lower tiller density was offset by larger tiller size. A similar relationship is reported for perennial ryegrass (Matthew et al. 1995). Bélanger (1996) found that the greater tiller density of late-maturing cultivars compensated for their lower total leaf length per tiller. There were also differences in tiller densities during the growing season. For example, tiller density of Climax and Richmond declined after first grazing and remained low in late summer and fall. In contrast, vegetative tiller density of Carol timothy increased at the third and fourth grazing. Preferential grazing of timothy cultivars, which may influence tiller survival, was not apparent in this study as differences in post-grazing stubble heights were insignificant. The proportion of unsown species was low (
