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Tall fescue (Lolium arundinaceum Schreb.) is the most predominant forage used in Southeastern United States for cow-calf production. Endophyte-infected tall fescue is easily established, adaptable to different environments and grazing tolerant, however alkaloids produced by the fungus cause metabolic disorders in animals referred to fescue toxicosis. Previous research has demonstrated cows consuming endophyte-infected tall fescue have decreased prolactin concentrations, decreased milk production and reduced growth performance in stacker calves. Animals have been shown to differ in degree of tolerance to endophyte-infected tall fescue. T-Snip is a commercial genetic test developed to identify tolerance of cattle to toxic tall fescue. The objective of this study was to analyze correlation between T-Snip test in cows consuming endophyte-infected tall fescue and 205-d weaning weights of their respective calves. We hypothesized T-Snip test score would be predictive of 205-d weaning weights of calves from cows consuming endophyte-infected tall fescue. Nine herds, with 4 herds tested 2 or more years, consuming endophyte-infected tall fescue were tested for fescue toxicity tolerance using the T-Snip genetic test between yr 2012 and 2015. Cows were scored from 0 to 5 for tolerance to fescue toxicity with zero being intolerant and 5 being most tolerant. Total of 2494 tests were performed and number of animals per herd ranged from 75 to 647. Correlation coefficient between cow tolerance score and 205-d weaning weights were measured for each herd and year data set. Correlation from each data set was significant (P < 0.02). The correlation coefficient averaged 0.63 and ranged from 0.42 to 0.76. Calf weaning weights from cows scored 0, 1, 2, 3, 4, and 5 averaged 212, 218, 226, 233, 240, and 246 kg, respectively. In conclusion T-Snip score from cows consuming endophyte-infected tall fescue was correlated to calf 205-d weaning weight and can be used as an indicator of tolerance to fescue toxicity. Difference in calf weaning weight between tolerant and intolerant cows averaged 28 kg. Tolerance to toxic tall fescue as determined by T-Snip analysis accounts for approximately one-half the effect of toxic tall fescue on calf weaning weight. [ABSTRACT FROM AUTHOR]

It is crucial for agricultural production to identify the trigger that switches plants from vegetative to reproductive growth. Agricultural sustainability in semiarid regions is challenged by nitrogen (N) fertilizer overuse, inadequate soil water, and heavy carbon emissions. Previous studies focused on the short-term effects of a single application of N and water but have not investigated the long-term effects of different irrigation and N fertilizer regimens on crop yields and yield components. N application is routinely coupled with water availability, and crop yields can be maximized by optimizing both. We examined the growth of western wheatgrass [Pascopyrum smithii (Rydb.) Á. Löve], a temperate-region forage and turf grass, using multiple different combinations of N fertilizer [(NH4)2·CO3] and irrigation levels over 3 years to determine optimal field management. We conducted multifactorial, orthogonally designed field experiments with large sample sizes, and measured fertile tillers m-2 (Y1), spikelets/fertile tillers (Y2), florets/spikelet (Y3), seed numbers/spikelet (Y4), seed weight (Y5), and seed yield (Z) to study factors associated with the switch between vegetative and reproductive growth. Fertilization had a greater effect on seed yield and yield components than irrigation. Y1 had the strongest positive effect on Z, whereas Y5 had a negative effect on Z. Irrigation and fertilization affected Z, Y1, and Y5. Fertilizer concentrations were positively correlated with Z, Y1, and Y5, whereas irrigation levels were negatively correlated. The ridge regression linear model results suggested N application rate and irrigation had antagonistic effects on Y1 (X3 = 867.6-4.23×X2; R2 = 0.988, F = Infinity, P<0.0001). We conclude that the optimal amount of N fertilizer and irrigation was 156 kg ha-1 + 115 mm for seed yield, 120 kg ha-1 + 146 mm for spikelets/fertile tillers, and 108 kg ha-1 + 119 mm for seed numbers/spikelets. These results will improve yield and reduce agricultural inputs for P. smithii in semiarid and arid regions, thereby reducing fertilizer pollution and conserving water., Competing Interests: The authors have declared that no competing interests exist.

Temperate grasses belonging to the Festuca-Lolium complex are important throughout the world in pasture and grassland agriculture. Tall fescue (Festuca arundinacea Schreb.) is the predominant species in the United States, covering approximately 15 million ha. Tall fescue has distinctive morphotypes, two of which are Continental (summer active) and Mediterranean (summer semidormant). This is the first report of a linkage map created for Mediterranean tall fescue, while updating the Continental map with additional simple sequence repeat and sequence-tagged site markers. Additionally, this is the first time that diversity arrays technology (DArT) markers were used in the construction of a tall fescue map. The male parent (Continental), R43-64, map consisted of 594 markers arranged in 22 linkage groups (LGs) and covered a total of 1577 cM. The female parent (Mediterranean), 103-2, map was shorter (1258 cM) and consisted of only 208 markers arranged in 29 LGs. Marker densities for R43-64 and 103-2 were 2.65 and 6.08 cM per marker, respectively. When compared with the other Poaceae species, meadow fescue (F. pratensis Huds.), annual ryegrass (L. multiflorum Lam.), perennial ryegrass (L. perenne L.), Brachypodium distachyon (L.) Beauv., and barley (Hordeum vulgare L.), a total of 171 and 98 orthologous or homologous sequences, identified by DArT analysis, were identified in R43-64 and 103-2, respectively. By using genomic in situ hybridization, we aimed to identify potential progenitors of both morphotypes. However, no clear conclusion on genomic constitution was reached. These maps will aid in the search for quantitative trait loci of various traits as well as help define and distinguish genetic differences between the two morphotypes., (© 2015 The Authors.)