Alfalfa and Timothy Nutritive Value in Contrasted Climatic Regions.

Forage nutritive value is known to be affected by temperature but little information exists on the effect of climatically-contrasted regions on forage nutritive value. We compared the nutritive value of forages produced in three contrasted sites in the province of Quebec, Canada (Sainte-Anne-de-Bellevue, 2098 degree-days; Saint-Augustin-de-Desmaures, 1712 degree-days; and Normandin, 1359 degree-days). Dry matter (DM) yield and stages of development of alfalfa (Medicago sativa L.) and timothy (Phleum pratense L.) were measured and forage samples were taken once a week for four to six weeks at each site during the primary growth of 2015 and 2016. Values of the nutritive attributes were fitted to the stages of development by quadratic functions and then predicted for a given stage of development. At the late bud stage of development for alfalfa, the neutral detergent fiber (NDF) concentration was less (428 vs. 485 and 468 g kg^-1 DM) and the forage in vitro true DM digestibility was greater (768 vs. 727 and 726 g kg^-1 DM) at Normandin than at Saint-Augustin-de-Desmaures and Sainte-Anne-de-Bellevue, whereas forage DM yield was lowest at Normandin (4.25 vs. 6.65 and 6.26 Mg ha^-1). At early heading for timothy, the forage NDF concentration was less at Normandin than at Saint-Augustin-de-Desmaures and Sainte-Anne-de-Bellevue (593 vs. 645 and 639 g kg^-1 DM), the in vitro true DM digestibility was greater at Normandin than at Saint-Augustin-de-Desmaures and similar at Sainte-Anne-de-Bellevue (831 vs. 786 and 826 g kg^-1 DM), but the forage DM yield was less at Normandin (4.17 vs. 6.39 and 5.11 Mg ha^-1). The greater nutritive value of timothy and alfalfa grown at the northernmost site (Normandin) was mainly explained by the well-established negative relationship between nutritive value and DM yield.