Sunn hemp (Crotalaria juncea L.) is an annual legume widely used as cover crop; however, there is potential to use it as forage. The objective of this study was to evaluate forage characteristics of 5 sunn hemp genotypes (HA, nutritive value, N fixation and nematode control), and beef heifer responses (intake and digestibility) to sunn hemp dietary inclusion. Two experiments were conducted at Ona, FL in 2016 and 2017. In Exp. 1, treatments were the factorial arrangement of five sunn hemp genotypes (AU Golden, Crescent Sunn, Ubon, This article is protected by copyright. All rights reserved. Blue Leaf and Red Mini) and two harvesting time (60 d after seeding or flowering) in a randomized complete block design. In Exp. 2, treatments were 100% sun hemp hay, 50% sunn hemp-50% bermudagrass [Cynodon dactylon (L.) Pers] hay, or 100% bermudagrass hay diets distributed in a completely randomized design. In Exp. 1, Crescent Sunn had the greatest HA [15.2 Mg dry matter (DM) ha-1 ], N fixation (81 kg N ha-1) and nematode control (80% reduction). AU Golden had the greatest crude protein (CP) concentration at 60 d after seeding and flowering (155 and 162 g kg-1 , respectively). In Exp. 2, increasing the proportion of sunn hemp in the diet decreased total forage DM intake (1.6, 1.4 and 1.2 as a % bodyweight with 0, 50 and 100% sunn hemp inclusion). Sunn hemp harvested 60 d after seeding is adequate to meet the nutritional requirements of most beef cattle categories but the genotype choice affects HA and nutritive value.

The objective of this study was to evaluate the effects of monensin on performance of beef heifers fed warm-season forages. Brangus heifers (n = 24) were stratified by BW and BCS, and randomly assigned into 1 of 12 bahiagrass pastures (1.2 ha and 2 heifers/pasture). Heifers were offered 14 kg of sugarcane molasses and 3.5 kg of cottonseed meal weekly from day 0 to 84. Treatments were randomly assigned to pastures (6 pastures/treatment) and consisted of heifers supplemented with or without 200 mg/day of monensin. On d 85, heifers were allocated to individual drylot pens, provided free choice access to bermudagrass hay, and received their respective treatment for 10 d of adaptation and 11 d of data collection. Monensin did not impact (P ≥ 0.13) heifer BW, BCS, overall ADG, bahiagrass IVDOM, CP, herbage mass, and allowance. Supplement disappearance after 10 and 34 h of supplementation was greater for control vs. monensin heifers (P = 0.04) and tended to be greater for control vs. monensin heifers 24 h post-supplementation (P = 0.07). Plasma concentrations of glucose, IGF-1, and BUN (P ≥ 0.24) did not differ between treatments. From d 85 to 106, forage and total DM intake, in vivo DM digestibility, and heifer growth performance did not differ between treatments (P ≥ 0.12). Therefore, adding monensin to sugarcane molasses-based supplements decreased supplement consumption rate, but did not impact growth and blood parameters of heifers grazing warm-season grasses with limited nutritive value.

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