Nutritive Value Attributes Research Articles

Timothy yield and nutritive value with a three-harvest system under the projected future climate in Canada

Jing, Q., Bélanger, G., Qian, B. and Baron, V. 2014. Timothy yield and nutritive value with a three-harvest system under the projected future climate in Canada. Can. J. Plant Sci. 94: 213–222. Timothy (Phleum pratense L.) is harvested twice annually in Canada but with projected climate change, an additional harvest may be possible. Our objective was to evaluate the impact on timothy dry matter (DM) yield and key nutritive value attributes of shifting from a two- to a three-harvest system under projected future climate conditions at 10 sites across Canada. Future climate scenarios were generated with a stochastic weather generator (AAFC-WG) using two global climate models under the forcing of two Intergovernmental Panel on Climate Change emission scenarios and, then, used by the CATIMO (Canadian Timothy Model) grass model to simulate DM yield and key nutritive value attributes. Under future climate scenarios (2040–2069), the additional harvest and the resulting three-harvest system are expected to increase annual DM yield (+0.46 to +2.47 Mg DM ha−1) compared with a two-harvest system across Canada but the yield increment will on average be greater in eastern Canada (1.88 Mg DM ha−1) and Agassiz (2.02 Mg DM ha−1) than in the prairie provinces of Canada (0.84 Mg DM ha−1). The DM yield of the first harvest in a three-harvest system is expected to be less than in the two-harvest system, while that of the second harvest would be greater. Decreases in average neutral detergent fibre (NDF) concentration (−19 g kg−1DM) and digestibility (dNDF, −5 g kg−1NDF) are also expected with the three-harvest system under future conditions. Our results indicate that timothy will take advantage of projected climate change, through taking a third harvest, thereby increasing annual DM production.

Timothy yield and nutritive value with a three-harvest system under the projected future climate in Canada

Jing, Q., Belanger, G., Qian, B. and Baron, V. 2014. Timothy yield and nutritive value with a three-harvest system under the projected future climate in Canada. Can. J. Plant Sci. 94: 213-222. Timothy (Phleum pratense L.) is harvested twice annually in Canada but with projected climate change, an additional harvest may be possible. Our objective was to evaluate the impact on timothy dry matter (DM) yield and key nutritive value attributes of shifting from a two- to a three-harvest system under projected future climate conditions at 10 sites across Canada. Future climate scenarios were generated with a stochastic weather generator (AAFC-WG) using two global climate models under the forcing of two Intergovernmental Panel on Climate Change emission scenarios and, then, used by the CATIMO (Canadian Timothy Model) grass model to simulate DM yield and key nutritive value attributes. Under future climate scenarios (2040-2069), the additional harvest and the resulting three-harvest system are expected to increase...

Benefits of mixing timothy with alfalfa for forage yield, nutritive value, and weed suppression in northern environments

Bélanger, G., Castonguay, Y. and Lajeunesse, J. 2014. Benefits of mixing timothy with alfalfa for forage yield, nutritive value, and weed suppression in northern environments. Can. J. Plant Sci. 94: 51–60. Alfalfa can be grown alone or with a grass, but little information exists on the benefits of mixing alfalfa (Medicago sativa L.) with a grass in northern environments. Our objectives were (1) to determine the benefits in terms of forage yield, nutritive value, and weed suppression of mixing timothy (Phleum pratense L.) with alfalfa and (2) to evaluate the persistence of alfalfa cultivars of varied adaptation to cold and of alfalfa populations selectively improved for superior freezing tolerance in a grass–legume mixture and in monoculture. This study was conducted in a region with 1700 degree-days (5°C basis) with one harvest in the seeding year (2008), three harvests in each of two post-seeding years, and one harvest in the third post-seeding year. Adding timothy to alfalfa increased the seasonal total dry matter (DM) yield by an average of 0.57 Mg DM ha−1 yr−1 in the first 2 post-seeding years and this seasonal effect was due mostly to a DM yield increase at the first harvest. The weed contribution to total DM yield in the three harvests of the first 2 post-seeding years was greater in the alfalfa monoculture (16 to 47%) than in the alfalfa–timothy mixture (12 to 36%). Mixing timothy with alfalfa also increased neutral detergent fibre concentration and digestibility, decreased N concentration, and tended to increase water soluble concentration, but had little effect on forage DM digestibility. Cultivars and populations recurrently selected for superior freezing tolerance did not differ in persistence and had a limited effect on DM yield and nutritive value attributes. The positive effect on DM yield of mixing timothy with alfalfa was not accompanied by a reduction in forage digestibility that is usually observed with increased DM yield.

Calibration and performance evaluation of the STICS crop model for simulating timothy growth and nutritive value

Several models for simulating the growth and nutritive value of forage crops have been developed in past decades but most of them are specific to one crop species and focus only on agronomic outputs. In this study, we calibrated and evaluated the performance of the STICS crop model for the simulation of the growth and nutritive value (cell wall concentration and digestibility, in vitro true dry matter [DM] digestibility, and N concentration) of timothy (Phleum pratense L.) under Canadian growing conditions. Equations used for calculating nutritive value attributes were derived from the CATIMO model (CAnadian TImothy MOdel). The calibration included two datasets, one for eastern Canada (cultivar Champ) and one for western Canada (cultivar Climax). Very good agreement between simulations and measurements was obtained for the calibration dataset (RMSE% ≤10% for all variables). Twenty-two datasets including leaf area index (LAI), forage DM yield, N concentration, cell wall concentration and digestibility, and in vitro true DM digestibility were then used to evaluate model performance. The model simulated LAI, forage DM yield, nitrogen concentration and nutritive value of the primary growth fairly well for all sites (RMSE% <30%), but was less successful for the regrowth (i.e. average RMSE of forage DM: 66.5 and 85.9gm−2 for primary growth and regrowth, respectively). The next step in this research will be to perform, multi-annual simulations to evaluate crop reserve simulations and improve regrowth simulation.

Yield and Composition of Sweet Pearl Millet as Affected by Row Spacing and Seeding Rate

Sweet pearl millet [Pennisetum glaucum (L.) R. BR.] seems promising for ethanol production, but optimal cropping practices are unknown for the cool and humid conditions of eastern Canada. We evaluated the effects of two row spacings (18 and 36 cm) and four seeding rates (5, 10, 15, and 20 kg ha−1) on biomass dry matter (DM) yield, water soluble carbohydrate (WSC) concentration and yield, and nutritive value of sweet pearl millet at two sites in Québec, Canada. Increasing seeding rates decreased biomass DM and WSC yields at Sainte‐Anne‐de‐Bellevue but had a limited effect at Saint‐Augustin‐de‐Desmaures. Hence, a seeding rate of 5 kg ha−1 resulted in maximum biomass DM (12.4–19.1 Mg ha−1) and WSC (1.56–2.64 Mg ha−1) yields. Row spacing did not affect biomass DM and WSC yields at Saint‐Augustin‐de‐Desmaures but biomass DM yield was greater at a row spacing of 18 cm at Sainte‐Anne‐de‐Bellevue. The WSC concentrations in leaves and stems were inconsistently affected by seeding rate but were not affected by row spacing. The WSC concentrations were greater in stems (140.7–162.4 g kg−1 DM) than in leaves (35.7–48.1 g kg−1 DM). Increasing the seeding rate generally decreased N concentrations of leaves and stems and digestibility of neutral detergent fiber (NDF) but increased concentrations of acid detergent fiber and NDF. Row spacing did not affect any nutritive value attributes. Seeding at 5 kg ha−1 with a row spacing of 18 cm maximize biomass and WSC yield with minimal effect on forage nutritive value of sweet pearl millet.

Drying procedures affect non-structural carbohydrates and other nutritive value attributes in forage samples

Forage non-structural carbohydrates (NSC) are an important source of energy readily available to rumen microbes. Sampling procedures that quickly reduce plant metabolic activity after cutting and preserve macromolecular structures are required for accurate estimation of forage NSC concentration and other nutritive value attributes. Although several drying procedures exist, their efficiency to reflect composition of fresh samples is unclear. We compared five drying procedures on fresh samples of timothy ( Phleum pratense L.) and alfalfa ( Medicago sativa L.): (1) oven-drying at 55 °C for 48 h; (2) high-temperature pretreatment at 100 °C for 1 h followed by oven-drying at 55 °C for 48 h; (3) freezing pretreatment at −20 °C for 1 mo followed by oven-drying at 55 °C for 48 h; (4) microwave pretreatment for 1 min followed by oven-drying at 55 °C for 48 h; and (5) freezing at −20 °C for 1 mo followed by freeze-drying. Starch, sucrose, glucose, fructose, fructans (timothy) or pinitol (alfalfa), N, neutral detergent fibre assayed with a heat-stable amylase (aNDF), acid detergent fibre (ADF), neutral detergent insoluble N (NDIN), and acid detergent insoluble N (ADIN) concentrations, and in vitro true digestibility of DM (IVTD) and digestibility of neutral detergent fibre (dNDF) were determined in the spring growth and summer regrowth of two production years. Soluble carbohydrate (SC) concentration was estimated using the sum of sucrose, glucose, fructose, and fructans or pinitol. The NSC concentration was obtained by adding SC and starch. Averaged across forage species and growth periods, NSC concentrations were similar and generally highest ( P<0.001) in freeze-dried samples (89.8 mg/g DM), the reference procedure, and the microwave-pretreated samples (86.7 mg/g DM); oven-drying at 55 °C resulted in the lowest NSC concentration (57.6 mg/g DM). Values of other nutritive value attributes with the microwave pretreatment were comparable to those of the other drying procedures, except that it tended to increase forage NDIN. The NDIN concentration was lowest ( P<0.001) in freeze-dried samples (2.1 mg/g DM) and generally highest in microwave-pretreated samples (7.5 mg/g DM). The effect of drying procedure on aNDF, ADF, IVTD, dNDF, and ADIN concentrations varied slightly with forage species and growth period. Principal component analysis (PCA) highlighted the closeness between freeze-drying and microwave pretreatment for the global assessment of the nutritive value of forages, including NSC concentration. Microwave pretreatment should be given greater consideration as an effective and easy-to-use sample preparation procedure for the characterization of the nutritive value of fresh forages.