The Impact of Foliar Fungicide Application on Barley Forage Yield, Silage Quality, and Performance of Lactating Dairy Cows
Year: 2025
Type: dissertation
Abstract: The objectives were to determine the effects of foliar fungicide application on two barley forage varieties, one resistant (CDC Fraser) and the other susceptible (Claymore) to foliar fungal disease, on forage yield, silage quality, feed intake, milk production and composition, rumen fermentation, omasal nutrient flow, total-tract nutrient digestibility, and nitrogen (N) balance in dairy cows. Twelve multiparous Holstein cows (mean DIM = 40 ± 17; mean BW = 720 ± 26 kg at the start of the experiment) were used in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement of dietary treatments. Experimental periods were 25 d, with 18 d of dietary adaptation and 7 d of sample and data collection. Test diets were: 1) fungicide-treated Claymore silage (CF); 2) untreated Claymore silage (CNF); 3) fungicide-treated CDC Fraser silage (FF); and 4) untreated CDC Fraser silage (FNF) as the major source of forage. Forage yields were 1.86 (FNF), 1.46 (CNF), 1.17 (FF), and 1.35 (CF) t DM/ha, likely reflective of the low rainfall during the growing season. Due to dry and hot weather conditions during the growing season, the presence of foliar fungal disease was minimal. Experimental silages were similar in crude protein (mean = 14.0%; DM basis), ammonia (mean = 1.95%), and total volatile fatty acid (mean = 9.25%) concentrations. CDC Fraser silage had higher lactic acid concentration (P < 0.001) but lower pH (P = 0.01) and acetic acid concentration (P < 0.01) than Claymore silage. Silage aNDF contents (DM%) were similar in FF and FNF, but greater in CNF than CF (interaction; P < 0.05). Without fungicide application, barley variety had no effect on silage starch content (DM%), whereas with fungicide application, Claymore had a greater silage starch content than CDC Fraser (interaction; P < 0.05). Dry matter intake, milk yield, and milk composition were unaffected by diet (P > 0.05). Total tract nutrient digestibility was unaffected by diet (P > 0.05). Intake of N, and urinary and fecal N excretion, total N excretion, milk N, and apparent N balance (expressed as g/d or % of N intake) were unaffected by diet (P > 0.05). Omasal fluid and particle flow were not affected by dietary treatment (P > 0.05). Ruminal short-chain fatty acid (SCFA) concentrations and pH were unaffected by diet (P > 0.05); however, total SCFA concentration was similar in CF and CNF but was greater in FNF than FF (interaction; P < 0.05). Valerate concentration was similar in FF and FNF but greater in CF than CNF (interaction; P < 0.05). These results suggest that foliar fungicide application on barley, regardless of variety susceptibility to fungal diseases, did not negatively affect silage quality or dairy cow performance.
Author: James, Christina S
Institution: University of Saskatchewan
Language: English
Subfield: Animal Science and Zoology
Domain: Life Sciences
SDG: Zero hunger
Open Access status: green
OpenAlex ID: W7119280022