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One possible approach for improving the nitrogen (N)‐use efficiency of perennial ryegrass (Lolium perenne L.) pastures and reducing environmental N losses is to select cultivars or incorporate alternative pasture species with lower shoot N concentrations. Viability of this strategy depends on herbage production not being unduly compromised. A pot experiment compared the shoot N concentration requirements of a diverse range of perennial ryegrass cultivars to achieve 90% and 99% of the herbage yield maxima achievable within a 20 day regrowth cycle. This research was undertaken to quantify if and what effect Australasian breeding programs have had on the N nutrition of perennial ryegrass. Our experiment found minimal genetic variation in the shoot N concentration requirements for vegetative perennial ryegrass swards to achieve near‐maximum herbage yields of living biomass. Across evaluated cultivars, swards achieving 90% and 99% of herbage yield maxima required minimum shoot N concentrations (on a dry matter basis) of 2.56% and 2.87%, respectively. Our experiment also evaluated the shoot N concentration requirements of modern summer‐active cocksfoot (syn. orchardgrass; Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb.) ecotypes. We found their shoot N concentration requirements to achieve optimal herbage growth to be similar to those of perennial ryegrass. Taken together, our results suggest that within the perennial ryegrass genome, and among similar high yielding temperate perennial grasses, there may be limited scope for selecting plants with lower shoot N concentration requirements. [ABSTRACT FROM AUTHOR]

Breeding for high magnesium (Mg) concentrations has been conducted for several forage species. Mgwell, Magnet, and HiMag are the first experimental strains, bred for increased Mg concentrations of orchardgrass, Italian ryegrass, and tall fescue, respectively. This experiment compared the performance and genetic variability of these high-Mg cultivars grown in solution culture with other cultivars in each species. Three mineral absorption experiments were carried out with one month aged seedlings. Seedlings were evaluated for shoot dry weight, uptake and concentration of Mg, calcium (Ca), and potassium (K), and also the density of these minerals in the shoot. The cultivars of different species behaved differently among the experiments even though the over all environmental condition was kept similar. The high-Mg cultivars showed higher Mg uptake per plant, but the differences were not so distinct. However, the trend in Mg concentration among the cultivars of different species was similar, and the difference between high-Mg cultivars and control cultivars was distinct. The Mg density in the shoot of these cultivars was significantly high. Also the high-Mg cultivars showed lower equivalent ratio, K/(Ca + Mg). Genotypic differences in high-Mg cultivars with others could be distinctly explained by differences in Mg concentration and Mg density in the shoot, which coupled with low K/(Ca + Mg) ratio. These common properties of high-Mg cultivars might be considered as a good parameter for screening. [ABSTRACT FROM AUTHOR]

Forage grass production is an important component of profitable dairying along the Pacific Northwest coast. Neutral detergent fiber digestibility (NDFD) is increasingly being used in ration formulation and forage benchmarking. However, data on differences in NDFD between and within cool-season grass species is limited. Therefore, the objective of this study was to determine if NDFD differs between and within species. In experiment 1, 15 cool-season grass varieties were replicated 3 times each in 6 m2 randomized field plots. Included were 5 varieties each of perennial ryegrass (Lolium perenne), orchardgrass (Dactylis glomerata), and tall fescue (Lolium arundinaceum). In experiment 2, three diploid and three tetraploid cool-season ryegrass varieties (Lolium perenne) were replicated 3 times each in 6 m2 randomized field plots. Plots were mechanically harvested six times at approximately 28 d intervals beginning in March. Forty eight-hour in vitro neutral detergent fiber (NDF) digestibility was determined using 0.3 g of sample in F57 bags in a DaisyII Incubator (Ankom Technology, Fairport, NY). In experiment 1, yield (2124±79 kg DM/ha/cutting) was similar across species. Neutral detergent fiber was less for ryegrass compared to orchardgrass (47.1 vs 48.5±0.4%; P < 0.01), but similar to both of these grasses was tall fescue (48.0%). Neutral detergent fiber digestibility was greater for ryegrass compared to orchardgrass and tall fescue (80.4 vs 77.5±0.6% of NDF; P < 0.01). Digestible NDF did not differ and was 37.4±0.3% of DM or 799±32 kg/ha/cutting. Neutral detergent fiber increased (linear; P < 0.01) and NDFD decreased (quadratic, cubic; P < 0.05) as the growing season progressed. In experiment 2, yield (2220±110 kg DM/ha/cutting), NDF (47.2±0.5%), NDFD (80.7±0.5%), and digestible NDF (38±0.4% of DM and 851±47 kg DM/ha/cutting) were similar for diploid and tetraploid ryegrasses. These results indicate species, when managed intensively, has little effect on yield and digestibility. [ABSTRACT FROM AUTHOR]