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.
On day 0 of year 1 and 2, sixty-four Brangus crossbred heifers per year were stratified by initial body weight (BW) and age (mean = 257 ± 20 kg and 271 ± 22 d) and allocated into 16 bahiagrass (Paspalum notatum) pastures (4 heifers/pasture/yr). Treatments were randomly allotted to pastures in a 2 × 2 factorial arrangement of treatments (4 pastures/treatment/yr). Treatments consisted of concentrate dry matter (DM) supplementation at 1.50% of BW from day 0 to 100 (CON) or concentrate DM supplementation at 1.05% of BW from day 0 to 49 and 1.95% of BW from day 50 to 100 (SST). Then, each respective supplementation strategy was added or not with immunomodulatory feed ingredient from day 0 to 100 (OMN; 4 g/45 kg of BW). Heifers were assigned to an estrus synchronization protocol from day 100 to 114. Heifers detected in estrus from day 111 to 114 were inseminated (AI) 12 h after estrus detection. Heifers not detected in estrus were timed AI on day 114. All heifers were exposed to Angus bulls from day 120 to 210 (1 bull/pasture). Effects of supplementation strategy × OMN inclusion × hour were detected (P < 0.0001) only for intravaginal temperature from day 26 to 30, which were the least (P ≤ 0.03) for SST heifers offered OMN supplementation and did not differ (P ≥ 0.17) among all remaining treatments from 0830 to 1600 h. Effects of supplementation strategy × OMN inclusion and OMN inclusion were not detected (P ≥ 0.12) for any variable, except for percentage of heifers detected in estrus, which was greater (P = 0.01) for heifers supplemented with vs. without OMN. Total concentrate DM offered from day 0 to 100 and heifer BW on days 0 and 56 did not differ (P ≥ 0.49) between CON and SST heifers, but SST heifers were heavier (P ≤ 0.01) on days 100 and 210 compared to CON heifers. Body surface temperature on day 25 and plasma IGF-1 concentrations on day 75 were greater (P ≤ 0.04) for SST vs. CON heifers. Percentage of pubertal heifers, heifers detected in estrus, and pregnancy to AI did not differ (P = 0.36) between SST and CON heifers but final pregnancy percentage was greater (P = 0.04) for SST vs. CON heifers. Thus, OMN supplementation decreased intravaginal temperature of SST heifers but failed to improve their growth and reproduction, whereas the SST strategy improved body thermoregulation, growth, and final pregnancy percentage of heat stressed Bos indicus-influenced beef heifers compared to a constant concentrate supplementation strategy.
Sunn hemp (Crotalaria juncea L.) is a warm‐season legume often used as a cover crop; however, there is limited information about nutrient cycling of sunn hemp residue. The objective of this study was to evaluate the effect of sunn hemp genotype and residue management on plant characteristics, decomposition, and suppression of Fusarium, Pythium, Sclerotinia, and Sclerotium microbe species. Two field experiments were conducted in Ona, FL. In Experiment 1, treatments were the split‐plot arrangement of three sunn hemp genotypes (Ubon, Blue Leaf, and ‘Tropic Sun’; main plot) and two biomass managements (removal or leaving the biomass on the field; subplot), distributed in a randomized complete block design. There was a greater biomass accumulation in 2019, but with no differences among genotypes (mean = 4,431 kg DM ha−1). Blue Leaf had greater N concentration than Ubon (23 vs. 19 g kg−1) and greater suppression of the Phytium populations than Ubon and Tropic sun in 2019 (0.9 vs. 2.0 colony forming unit g soil−1). In Experiment 2, the litter bag technique was used to estimate biomass and N decomposition. Treatments were the factorial arrangement of three genotypes and two residue management strategies (incorporated into the soil or placed on the soil surface). Sunn hemp biomass incorporation enhanced organic matter disappearance and N mineralization rate but leaving sunn hemp on the soil surface may result in a steadier N supply for the subsequent crop.
The effects of application of bovine urine on biomass and nitrogen (N) accumulation in 3 tropical grasses (Urochloa decumbens cv. Basilisk, U. humidicola cv. Humidicola and Megathyrsus maximus cv. Mombasa), and on available N concentrations in soil (NH4+-N, NO3--N) were studied using a randomized complete block design with 3 replicates. There were significant interactions between species and urine application over time in terms of herbage accumulation and N concentration (P<0.01), with significant differences in the concentrations of N available in the soil (P<0.01). Soil temperature and precipitation had important effects on the concentrations of both soil ions. Application of bovine urine increased dry matter accumulation of all grasses in the short term and of U. decumbens over the whole year. Application of urine increased soil N levels, but for U. humidicola and M. maximus the effects were transient. It is necessary to continue with longer-term studies in the Piedmont plains to determine the effects of livestock grazing on the biogeochemical cycles, environmental impacts and natural mitigation options that the ecosystem offers, e.g. CO2 sequestration, biological nitrification inhibitors and organic matter decomposition.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.