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Evaluating the establishment of perennial forages with annual warm-season grasses as companion crop on forage yield and quality.

S. Thevakumaran

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06-23-2020

Abstract:

236
Evaluating the establishment of perennial forages with annual warm-season grasses as companion crop on forage yield and quality.
S. Thevakumaran*1, C. Matteau2, B. Baurhoo1,2, P. Seguin1, A. Mustafa1. 1McGill University Saint Anne de Bellevue, QC, Canada, 2Belisle Solution Nutrition Inc Saint-Mathias-sur-Richelieu, QC, Canada.

The use of annual warm-season grasses as companion crops in the establishment of perennial forages have not been fully explored. This study evaluated forage yield, chemical composition and in vitro total-tract NDF digestibility (TTNDFD) of perennial mixtures (alfalfa, clover and tall fescue; control) seeded solely or with an annual companion crop [Sudangrass (SG), Sudangrass brown midrib (BMR) gene 12 (BSG), Sorghum-Sudangrass BMR gene 6 (BSSG) or oat]. Experimental plots (8 replicates per treatment) were harvested 60 d (1st cut) and 90 d (2nd cut) after planting at bud stage of alfalfa. The TTNDFD was estimated from potentially digestible NDF (pdNDF), digestion rate (kd) and passage rate (kp) while forage indigestible NDF (iNDF) was calculated from 240 h in vitro incubation. Potentially degradable NDF was calculated by subtracting iNDF from total NDF whereas digestion rate of pdNDF was estimated by in vitro incubation at 24, 30 and 48 h. Data were analyzed as repeated measures using the MIXED procedure of SAS with fixed effects of treatment and cut. Results showed that total forage yield (2 cuts; DM basis) was higher (P < 0.0001) for SG (6.8 T/ha), BSSG (6.7 T/ha) and BSG (6.3 T/ha) than control (4.1 T/ha). Oat produced 87% less forage yield in the second cut than first cut. Companion forages reduced (P < 0.0001) the yield of perennial legumes and weeds. Relative to control, companion forages reduced (P < 0.0001) lignin and crude protein but increased (P < 0.0001) NDF and ADF contents of harvested forages. Water-soluble carbohydrate concentration was highest with oat (12.4%), intermediate with SG (9.5%), BSG (9.1%) and BSSG (10.7%) and lowest with control (7.0%). Estimated milk yield was higher (P < 0.0001) with companion forages than control. In vitro TTNDFD of second cut followed the order (P < 0.0001): BSG and BSSG (average 62.2%) > SG (58.5%) > oat (53.3%) > control (52.3%). The iNDF was lower (P < 0.0001) with BSSG than control and oat treatment. In conclusion, establishing perennial forages with SG, BSG or BSSG may improve forage yields, nutritive value and fiber digestibility.

Keywords: cow, forage, fiber digestibility.

Biography: I, Ms. Sayanthika Thevakumaran, am a citizen of Sri Lanka. I am a Masters student in the department of Animal Science at McGill University since August 2018. I am very passionate about improving the nutrition of dairy cows. My research project is very innovative. For the first time, we are investigating the potential use of annual gramineaes forages, specifically Sudangrass and Sorghum-Sudangrass, in establishing new alfalfa fields to improve forage yields and forage quality. Results, so far obtained, are extremely interesting and may have immediate application in the dairy industry. Briefly, findings of this study may lead dairy producers to reconsider their seeding strategies when establishing new alfalfa fields.