Yield and nutritive value of timothy as affected by temperature, photoperiod and time of harvest

Abstract

Scenarios of global climate change forecast an increase in air temperature of 3°C over the next 100 years in eastern Canada. Growth and nutritive value of cool-season grasses are known to be affected by air temperature. It is also believed that grasses grown at high latitude have a greater nutritive value. The objectives of this study were to assess the effect of four combinations of day ⁄ night temperature and photoperiod (15 h-17 ⁄ 5°C; 15 h-22 ⁄ 10°C; 15 h-28 ⁄ 15°C; and 17 h-17 ⁄ 5°C) on dry-matter (DM) yield, in vitro true DM digestibility (IVTD), in vitro digestibility of neutraldetergent fibre (NDF), and concentrations of NDF, acid-detergent fibre (ADF), lignin, minerals and nonstructural carbohydrates (NSC) in timothy grown under controlled conditions. Furthermore, herbage was harvested in the morning and in the afternoon to assess the impact of the time of harvest. The dietary cation-anion difference [DCAD = (K + + Na + ) ) (Cl ) + 0AE6 S 2) )] and the grass tetany index [GT index = K + ⁄ (Ca 2+ + Mg 2+ )] were also calculated. Higher temperature regimes significantly decreased IVTD and digestibility of NDF but had a limited effect on concentrations of NDF, ADF and lignin. DM yield of herbage was less and the concentration of NSC was greater in timothy grown under a temperature regime of 28 ⁄ 15°C than the 17 ⁄ 5°C and 22 ⁄ 10°C regimes; this effect is mainly explained by a response to temperature stress. Values of DCAD and the GT index of herbage were also lower under the 28 ⁄ 15°C than the 17 ⁄ 5°C and 22 ⁄ 10°C regimes as a result of a decreased plant K concentration. Under the 17 ⁄ 5°C regime, an increase in 2 h of photoperiod resulted in increased DM yield, decreased concentrations of K, Ca, Mg, Cl and N, and an increased starch concentration; IVTD or digestibility of NDF were not affected, although lignin concentration was reduced.Harvesting timothy in the afternoon rather than in the morning resulted in higher NSC, mainly sucrose, concentrations, and decreased ADF and NDF concentrations. The forecasted increase in air temperature in eastern Canada over the next 100 years will result in lower yields and nutritive value of timothy.

Nutritional Quality of Herbaceous Vegetation in a Phryganic Mediterranean Ecosystem During the Grazing Period

“…Mineral and ash concentrations diminished from the second month of harvest (April) onwards showing their lowest values in July. Similar trends in mineral and ash concentration were found by Mountousis et al (2006; and can be caused by the increased air temperature (Bertrand et al, 2008) and its negative impact on plant mineral intake from the soil (Wang et al, 2006). Also, the reduction in mineral and ash content during plant growth has been attributed to the increased dry matter yield due to dilution of minerals in plant tissue (Pelletier et al, 2006).…”

How can forage production in Nordic and Mediterranean Europe adapt to the challenges and opportunities arising from climate change?

“…Higher temperatures lead to earlier stem elongation, a faster rate of decline in cell wall digestibility of both vegetative and reproductive tillers during aging, and hence faster decline in the digestibility of forages (Groot et al, 2003;Thorvaldsson et al, 2007;Bertrand et al, 2008;Bloor et al, 2010;Jing et al, 2013). In addition, higher standing biomass is associated with higher stem-to-leaf proportions and lower digestibility, at least in timothy (Bélanger and McQueen 1998;Bélanger et al, 2001), and thus climate change may lead to lower or higher digestibility through its effect on growth rate, stand density and competition for light.…”

Development of yield and nutritive value of timothy in primary growth and regrowth in northern growing conditions

“…A rise in temperature has the effect of increasing the rate of decline in digestibility in the first crop (Thorvaldsson 1987, 2006, Rinne et al 2001, Sihto and Rinne 2008. The optimum daytime temperature for the growth of timothy in summer appears to be around 17 o C (Bertrand et al 2008, Nordheim-Viken et al 2009). Under cooler temperatures, dry matter digestibility has been higher as a result of increase in cell wall digestibility and partly of delay in reaching a certain stage of development.…”

“…The low temperature has the effect of decreasing the crude fibre content of the dry matter. According to Bertrand et al (2008), the higher dry matter digestibility of timothy grown under cool temperatures was caused by an increase in cell wall digestibility, in part due to the delay in reaching a given stage of development under cooler temperature. The different development of regrowth digestibility compared to that of primary growth may be caused by the lower growing temperatures having a retarding impact on lignin synthesis (Van Soest et al 1978) and the proportion of leaves in the total herbage mass not declining with the advance in grass growth during late summer (Åman andLindgren 1983, Rinne et al 2000).…”