|OTTMAN, MICAEL - University Of Arizona|
Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 4/5/2021
Publication Date: N/A
Technical Abstract: Recently, there has been increased interest in including triticale (X Triticosecale Wittmack) or other winter cereals within forage programs throughout the southwest USA. Our objectives were to screen 14 diverse triticale cultivars for agronomic and nutritive characteristics with specific emphasis on identifying normal, as well as deviant, responses to calendar date and plant maturity throughout late-winter and spring. Fourteen cultivars were established at Maricopa, AZ in a randomized complete block design with each cultivar represented within each of 3 field blocks. Plots were established on 18 December 2018, and then harvested at 2-wk intervals beginning on 27 February and ending 23 May 2019. Across all harvest dates (N = 315 forages), forage energy density (NEL) exhibited strong negative correlations (P < 0.001) with growth stage (r = - 0.879), plant height (r = - 0.913), head weight (r = - 0.814), and estimated dry matter (DM) yield (r = - 0.886), but was positively associated with percentage of leaf (r = 0.949; P < 0.001), and weakly associated with percentage of stem (r = 0.138; P = 0.014). Through 10 April, similar correlations were observed within individual harvest dates (N = 45 forages) for growth stage (r = - 0.439; P = 0.03), leaf percentage (r = 0.274; P = 0.068), and plant height (r = -0.578; P = 0.012), but not consistently for stem or head percentages. Within later harvest dates, only sporadic correlations with NEL were observed. Mostly cubic regression models best explained relationships for neutral-detergent fiber, acid-detergent lignin, 30- and 48-h in-vitro disappearance of DM and fiber, and NEL with days from 1 February or growth stage. Coefficients of determination (R2 = 0.860) in all cases indicated good fit for the polynomial models. When days from 1 February was used as the independent regression variable, maximum deviations from the normal or typical cultivar were largely associated with cultivar maturation rate. However, when growth stage was substituted as the independent variable, plant height, stem percentage beginning at anthesis, and head percentage were associated with the maximum negative deviation from normal. The 0.23 Mcal/kg differential between the most extreme positive and negative deviant cultivars for NEL at a common late-boot/early-heading stage of growth suggests careful attention should be placed on cultivar selection, in addition to forage inventory needs and overall cropping goals.