|Akins, Matthew - University Of Wisconsin|
|Cavadini, Jason - University Of Wisconsin|
Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/14/2018
Publication Date: 6/25/2018
Citation: Coblentz, W.K., Akins, M.S., Kalscheur, K., Brink, G.E., Cavadini, J.S. 2018. Effects of growth stage on quality characteristics of triticale forages. Journal of Dairy Science. 101 (suppl. 2):63.
Technical Abstract: The use of triticale (X Triticosecale Wittmack) in dairy-cropping systems has expanded greatly in recent years, partly to improve land stewardship by providing winter ground cover. Our objectives were to relate the nutritive value of triticale forages grown in central Wisconsin with plant growth stage. Replicated 3.7 × 9.1-m plots of triticale were harvested at various growth stages during spring/early-summer of 2016 and 2017. Growth stages were quantified using a linear staging system that is suitable for use as a continuous, independent regression variable; growth stages ranged from 20 to 29 for tillering up to 80 to 89 for seed ripening. In 2016, the mean DM yield at the boot stage (3,804 kg DM/ha) was only 30% of that observed at the soft-dough stage of growth (12,642 kg DM/ha). Although DM yields were reduced in 2017, primarily due to spring flooding, the percentage of forage DM harvested at boot stage compared with soft-dough was similar (26.9%; 1453 vs. 5399 kg DM/ha). Regressions of DM yield (kg/ha) on growth stage for 2016 were explained by a cubic model (Y = 0.0663 x3 – 9.44 x2 + 595 x – 9810; R2 = 0.985) compared to a simple linear response for 2017 (Y = 103 x – 3024; R2 = 0.934). Many nutritional characteristics, such as NDF, were affected by the juxtaposition and balance of two generally competing factors: i) increased concentrations of structural plant fiber as plants matured; and ii) the accumulation of highly digestible carbohydrate during seed-head development. As such, the relationship between NDF and growth stage was best fitted to higher-ordered models for 2016 (Y = 0.0000369 x4 - 0.00886 x3 + 0.745 x2 – 25.4 x + 342.5, R2 = 0.975) and 2017 (Y = - 0.000570 x3 + 0.0828 x2 – 3.14 x + 74.9, R2 = 0.950). Single-endpoint estimates of in-vitro NDF digestibility after 24, 30, or 48-h incubations declined with plant maturity, and were closely related (R2 = 0.906) to growth stage by linear or quadratic regression models that were similar across production years. Typical recommendations for harvesting triticale at boot stage to facilitate the planting of double-cropped corn are strongly supported by the extensive 30-h in-vitro disappearance of NDF at that growth stage, which comprised 63.1 ± 1.79 and 64.8 ± 7.39% of NDF for 2016 and 2017, respectively.