Yield and nutritional quality of deferred sorghum hybrids

LAGRANGE, SEBASTIAN; ARELOVICH, HUGO MARIO; VASICEK, JUAN PABLO; BRAVO, RODRIGO DAMIÁN; MARTÍNEZ, MARCELA FERNANDA

Indianapolis

Congreso; ADSA-ASAS-CSAS Joint Annual Meeting 2013; 2013

ADSA-ASAS-CSAS

Forage deferral should improve winter food availability and quality for cow-calf grazing systems of semiarid Argentina. The objective was to determine morphometric characteristics, biomass yield and nutritional quality of forage harvested from sorghum hybrids (SH) as affected by deferral period through winter. SH and seed companies were: VDH 205 (grain), VDH 422 (silage), Sugargraze (forage-silage), VDH 701 (forage-photosensitive), all from Advanta; Lucero BMR (forage) from La Tijereta; and Pegual (Sudan-forage) from Génesis. SH were planted in 1.6 × 15 m-plots in a complete randomized block design. Plant density was 20, 25 and 35 plants/m2 for grain, silage and forage SH respectively. Winter clipping intervals were 194-d (C1), 229-d (C2) and 246-d (C3) after planting on December 4. Forage was cut at 5 cm, and crude protein (CP), in vitro dry matter digestibility (IVDMD), and neutral detergent fiber (NDF) were determined. Pegual developed 44 tillers/m2 followed by VDH 701 with 37 (P < 0.05). VDH701 and Sugargraze were the tallest with surpassing 270 cm in C1 and C2, staying taller VDH701 in C3 (P < 0.05), with the largest DM yield. Overall, a 32 % reduction in DM yield was found in C3. For VDH 205 and 422 prevailed heads (C1 and C2) increasing sheath fraction in C3. For VDH 701 and Sugargraze prevailed sheaths, as well as for Lucero and Pegual, with more heads compared to the other forage-SH. Sugargraze and VDH 701 exhibited the lowest DM content across cutting dates: 32 to 33% versus 50-60% for the other SH (P < 0.05). IVDMD decreased by cutting date: 60.7, 56.2 and 49.0 for C1, C2 and C3 respectively, being greater for VDH205, Sugargraze and VDH422. Sugargraze, VDH422 and VDH205 had the lowest NDF content which increased with cutting date. VDH205 had the highest average CP content (6.7%) followed by VDH422 (5.3 %) both steady across time; CP content only decreased in C3. Overall VDH422 had the best performance. SH can contribute with higher DM yield and better quality than other deferred forages to improve calf crop and land use efficiency