Dietary cation–anion difference of Timothy (Phleum pratense L.) as influenced by application of chloride and nitrogen fertilizer

The effectiveness of forages to prevent post‐calving hypocalcaemia, when used as a feed source for non‐lactating dairy cows, can be predicted by the dietary cation–anion difference (DCAD). Three to four weeks before calving, the ration of non‐lactating dairy cows should have a DCAD around ?50 mmol_c kg^?1 DM. In an experiment, swards, based on Timothy (Phleum pratense L.), were used to (i) evaluate the impact of two types (CaCl₂ and NH₄Cl) and four application rates of chloride fertilizer per season (0, 80, 160 and 240 kg Cl ha^?1) in combination with two N application rates (70 and 140 kg N ha^?1) on mineral concentrations and DCAD in the herbage, and (ii) determine the economically optimal rate of chloride fertilizer (Cl_op) for DCAD in herbage. Chloride and N fertilizers were applied in the spring and, after the first harvest in 2003 and 2004 at four locations that differed in K content of their soils. Two harvests were taken during each year. Averaged across N‐fertilizer application rates, harvests and locations, the highest rate of chloride fertilizer increased chloride concentration in herbage by 8·5 g kg^?1 dry matter (DM) and decreased DCAD in herbage by 190 mmol_c kg^?1 DM to values as low as ?9 mmol_c kg^?1 DM. Both types of chloride fertilizer had the same effect on chloride concentration and DCAD in herbage and had no effect on DM yield. When no chloride fertilizer was applied on soils with a high content of available K, application of N fertilizer increased DCAD in herbage by 47 mmol_c kg^?1 DM at both harvests. Herbage DCAD was lower in summer than in spring by 47–121 mmol_c kg^?1 DM depending on the location. Application of chloride fertilizer can effectively lower the DCAD of Timothy‐based herbages; the economically optimal rate of chloride fertilizer in the spring varied from 78 to 123 kg Cl ha^?1, depending on soil K and chloride contents and expected DM yield.     

Morphology,tannin concentration and forage value of 15 Swiss accessions of sainfoin (Onobrychis viciifolia Scop.) as influenced by harvest time and cultivation site

Fifteen accessions of sainfoin (Onobrychis viciifolia Scop.) were characterized for morphological and phenological traits at Reckenholz in the Swiss lowlands (Experiment 1). The effects of accession, harvest time and site on dry‐matter yield, condensed tannin (CT) concentration and forage value (Experiment 2) were determined at three sites in Switzerland varying in altitude from 440 to 559 m. Three to four harvests were taken in the first year after establishment (second year of stand) with harvests 1 and 2 chemically analysed. From the characterization in Experiment 1, a clear grouping of single flowering (Communis) and multiple flowering (Bifera) accessions emerged. Additionally, within the Communis accessions, distinct groupings were identified (historical landraces and newly collected ecotypes) based on morphological characteristics. Experiment 2 showed that Communis and Bifera accessions had a similar chemical composition in the first harvest. In the second harvest, Communis accessions were higher in crude protein and CT and lower in neutral and acid detergent fibre concentrations than Bifera accessions. Total dry‐matter yields were higher for Bifera accessions. Among the Communis accessions, ecotypes had consistently higher CT concentrations than landraces. In vitro organic matter digestibility did not significantly differ among accessions. There were clear effects of harvest time and site for most variables, with clear harvest time × sainfoin group interaction but no site × sainfoin group interactions. The results clearly demonstrate that historical landraces and newly collected ecotypes expand the range of available genetic variation for sainfoin breeding.