Track 1-11

Description

Alfalfa proteins are extensively degraded during wilting, silage fermentation, and in the rumen. To efficiently use alfalfa non protein N, rumen microbes need a readily available energy source such as nonstructural carbohydrates (NSC); otherwise, surplus N in the form of rumen ammonia is converted into urea and excreted in the environment. Increasing the NSC concentration of alfalfa was thus the focus of our research program. Our objectives were to assess the impact of high NSC alfalfa on digestibility and microbial protein synthesis measured in vitro, and on ingestion, rumen metabolism, N use efficiency, and dairy cow performance. Increasing NSC concentration of alfalfa significantly enhanced in vitro dry matter (DM) digestibility and decreased NH3-N concentration in rumen fluid. An increase of 23 g/kg in alfalfa NSC concentration can improve forage DM intake (+5 %) and energy corrected milk production (+8 %). Feeding high-NSC alfalfa led to a higher rumen pH, suggesting that sugars do not cause rumen acidosis, and to a lower milk urea N (MUN) indicating an improvement in N utilization. Increasing NSC concentration of alfalfa is a low-cost tool to improve its utilisation in dairy rations and potentially mitigate the environmental footprint of milk production.

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High-Sugar Alfalfa for Dairy Cows

Alfalfa proteins are extensively degraded during wilting, silage fermentation, and in the rumen. To efficiently use alfalfa non protein N, rumen microbes need a readily available energy source such as nonstructural carbohydrates (NSC); otherwise, surplus N in the form of rumen ammonia is converted into urea and excreted in the environment. Increasing the NSC concentration of alfalfa was thus the focus of our research program. Our objectives were to assess the impact of high NSC alfalfa on digestibility and microbial protein synthesis measured in vitro, and on ingestion, rumen metabolism, N use efficiency, and dairy cow performance. Increasing NSC concentration of alfalfa significantly enhanced in vitro dry matter (DM) digestibility and decreased NH3-N concentration in rumen fluid. An increase of 23 g/kg in alfalfa NSC concentration can improve forage DM intake (+5 %) and energy corrected milk production (+8 %). Feeding high-NSC alfalfa led to a higher rumen pH, suggesting that sugars do not cause rumen acidosis, and to a lower milk urea N (MUN) indicating an improvement in N utilization. Increasing NSC concentration of alfalfa is a low-cost tool to improve its utilisation in dairy rations and potentially mitigate the environmental footprint of milk production.