BILL E. KUNKLE INTERDISCIPLINARY BEEF SYMPOSIUM: A meta-analysis of research efforts aimed at reducing the impact of fescue toxicosis on cattle weight gain and feed intake1

Abstract

The objective of this paper is to present a systematic review and meta-analysis of research efforts aimed at recovering cattle production losses attributed to toxic endophyte-infected [ (Morgan-Jones & Gams.) Glenn, Bacon, & Hanlin comb. Nov.] tall fescue [ (Schreb.) Darbysh.]. The strategies presented include those 1) applied with forage systems, 2) based on pharmacological compounds and functional foods, and 3) based on supplemental dietary nutrients. Cattle BW gain and DM intake was the dependent response evaluated. Among the forage systems reviewed, studies with nontoxic, endophyte-infected tall fescue as a total replacement forage system demonstrated the greatest improvement in per-hectare (152 ± 27.5 kg/ha) and per-animal (0.29 ± 0.03 kg/d) BW gain. Studies with interseeded legumes have exhibited a small and highly variable BW gain effect size per hectare (52 ± 24.1 kg/ha) and per animal (0.11 ± 0.03 kg/d). The legume response was seasonal, with summer exhibiting the greatest benefit. Studies with chemicals that suppress plant growth demonstrated BW gain responses (0.17 ± 0.06 kg/d) equal to or greater than the response observed with legume studies. Cattle grazing toxic tall fescue responded well to anthelmentics, antimicrobial feed additives, and steroid implants, and the use of these technologies may additively help recover production losses. As a group, functional foods have not improved BW gain ( = 0.85). Studies with cattle supplemented with highly digestible fiber supplements observed a 0.15 kg greater BW gain compared with studies using starch- and sugar-based supplements ( < 0.05). Weight gain was positively impacted by the level of supplementation (0.06 kg/DM intake as percent BW). Supplement feed conversion was estimated at 6:1 for the highly digestible fiber supplements compared with 11:1 for starch-based supplements. Tall fescue forage DM intake was predicted to maximize at a supplemental feeding rate of 0.24% BW with a breakpoint at 0.5% BW, and total maximum DM intake (forage plus supplement) occurred at 2.7% BW when supplemental feeding approached 0.9% BW. Results from this meta-analysis should be useful for 1) establishing and comparing measured responses to theoretical improvements in BW gain when additive strategies are considered, 2) research planning, and 3) producer education.

Meta-analysis of the effects of monensin on growth and bloat of cattle on pasture

“…BW gain converted to ADG). For studies that did not report SEM for a continuous response variable or a response was calculated from available data, an estimate of SEM was determined arithmetically from P -values ( Idris and Robertson, 2009 ; Gadberry et al, 2015 ). When P -value thresholds were provided, α = 0.05 was used for P < 0.05.…”

Ecological Intensification of Food Production by Integrating Forages

“…In some cases, these limitations cause such variability in success, even under research conditions, that producers are hesitant to adopt these strategies. For example, legume inclusion in endophyte-infected tall fescue research does not guarantee an increase in animal gain [108], leaving producers unsure about whether to adopt the practice because of additional risk associated with seed and establishment costs.…”

Meta-analysis of the effects of monensin on performance of beef replacement heifers and beef cows

“…To minimize study exclusion, missing continuous responses were calculated from available data (e.g., weight gain converted to ADG). For studies that did not report SEM for a continuous response variable, or a response was calculated from available data, an estimate of SEM was determined arithmetically from P values ( Gadberry et al, 2015 ). When P value thresholds were provided, α = 0.05 was used for P < 0.05.…”