Yield and forage quality of kura clover (Trifolium ambiguum Bieb.) and intermediate wheatgrass [Thinopyrum intermedium (Host.) Barkw. & D.R. Dewey] mixtures compared with commonly grown forages such as alfalfa (Medicago sativa L.) and smooth bromegrass (Bromus inermis Leyss.) have not been fully explored. Our objective was to evaluate the effects of alfalfa, birdsfoot trefoil (Lotus corniculatus L.), and kura clover grown in binary mixtures with orchardgrass (Dactylis glomerata L.), smooth bromegrass, and intermediate wheatgrass on seasonal distribution of forage yield and quality. Plots of each species in monoculture and binary legume–grass mixtures were established in a randomized complete block design in 1994 near Boone, IA. Yield was measured monthly during the 1995 and 1996 seasons. In vitro dry matter digestibility (IVDMD), neutral‐detergent fiber (NDF), and crude protein (CP) concentrations were determined for each monoculture or mixture. Total yield was highest for monoculture alfalfa, alfalfa–intermediate wheatgrass, and alfalfa–smooth bromegrass with 13400, 12700, and 12600 kg ha−1 respectively in 1995, and 7500, 6800, and 6700 kg ha−1 respectively, in 1996. Kura clover had the lowest NDF (357 g kg−1) and highest IVDMD (740 g kg−1) concentrations compared with other forages. Yield, CP, and IVDMD concentrations of monoculture grasses were lower than those of the legume–grass mixtures or of the monoculture legumes. Legumes improved the seasonal distribution of yield and forage quality by beig more productive at later harvests. Yield of alfalfa–intermediate wheatgrass was equal to or better than other alfalfa–grass mixtures and could make a valuable legume–grass alternative.
No abstract
Complete information on forage quality characteristics of amaranth is unavailable. This study evaluated the forage quality of various amaranth accessions at different harvest dates. Seven accessions from the North Central Plant Introduction Station were established in June 1997 and June 1998 near Boone, IA. Subplots were harvested six times at 2‐wk intervals beginning 42 d after planting (DAP). In vitro dry matter digestibility (IVDMD), neutral detergent fiber (NDF), crude protein (CP), nitrate‐nitrogen, acid detergent fiber (ADF), acid detergent lignin (ADL), protein and fiber digestion, and undegradable intake protein (UIP) were determined. Averaged over accessions, IVDMD decreased (P < 0.05) from 780 g kg−1 at 42 DAP to 680 g kg−1 at 112 DAP. Digestibility ranged from 590 to 790 g kg−1 Averaged over accessions at 42 DAP, CP was 270 g kg−1 then decreased to 100 g kg−1 at 112 DAP. Neutral detergent fiber increased from 310 g kg−1 at 42 DAP to 430 g kg−1 at 112 DAP. Averaged over harvest date, Amaranthus cruentus (Zimbabwe) had the highest NDF (390 g kg−1), and A. hybrid (Puebla, Mexico) had the lowest (330 g kg−1). Amaranthus cruentus (Zimbabwe), A. cruentus (Rwanda), and A. hybrid (Puebla, Mexico) had UIP averaging 25, 22, and 16%, respectively, of total crude protein after 16 h of digestion. Forage quality of the accessions at most harvest dates was consistent with what would be expected for relatively good quality forage, although high nitrate levels are a concern.
Aminopyralid is a new auxinic herbicide that provides Canada thistle control at lower use rates than clopyralid. Studies were conducted to determine if differences in absorption, translocation, or metabolism account for aminopyralid's greater biological activity. Radiolabeled aminopyralid and clopyralid were applied to individual leaves of rosette-stage Canada thistle plants. Nonionic surfactant was used for the absorption studies because it provided higher aminopyralid absorption than methylated seed oil or crop oil concentrate. Clopyralid was absorbed very rapidly, reaching 72% 24 h after treatment (HAT) and remaining near or above 80% during a 192-h time course. During the same time period, aminopyralid absorption increased from 34 to 60%. Clopyralid translocation out of the treated leaf was significantly higher than aminopyralid, 39% compared with 17%, respectively, 192 HAT. More of applied clopyralid translocated to aboveground tissue 192 HAT (27%) than to roots (12%), whereas aminopyralid translocation was similar in aboveground tissue (10%) and roots (7%) 192 HAT. Neither aminopyralid nor clopyralid was metabolized 192 HAT. Although aminopyralid is effective at lower use rates than clopyralid, clopyralid absorption and translocation were higher in Canada thistle. These results suggest that aminopyralid's chemical structure may provide for greater biological activity at the target site than clopyralid.
Chaparral herbicide has been shown to suppress seedhead emergence in tall fescue [Lolium arundinaceum (Schreb.) Darbysh] and potentially mitigate the effects of fescue toxicosis. A two‐year grazing experiment evaluated steers grazed on endophyte‐infected fescue–Kentucky bluegrass (Poa pratensis L.) pastures either treated or untreated with Chaparral herbicide to determine if seedhead suppression alleviates fescue toxicosis and increases average daily gain (ADG). Treatments were assigned to six, 3.0‐ha fescue‐bluegrass pastures in a randomized complete block design with three replications. Pastures were grazed with 48 steers (2.7 steers ha−1) from 9 Apr. to 1 July 2009 and 6 Apr. to 7 July 2010. Reproductive tiller densities in treated pastures were low in both years (<7 m−2) in comparison with untreated pastures (113 and 69 tillers m−2 in 2009 and 2010, respectively). Ergovaline and ergovalinine concentrations were three‐ to sixfold greater in seeds than in leaf blades and sheaths of vegetative and reproductive tillers. Crude protein, water soluble carbohydrates, and in vitro digestible dry matter concentrations of tillers declined over time at a greater rate in untreated than in treated pastures. Steers on treated pastures had greater (P < 0.01) ADG, lower (P < 0.10) rectal temperatures, and greater (P < 0.01) serum prolactin concentrations. Results indicated that Chaparral herbicide can suppress reproductive development of fescue to increase ADG and reduce the severity of toxicosis.
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