Effect of Interseeded Clovers on Forage Quality of Annual Ryegrass Pastures Grazed By Stocker Cattle.

In the first year of a three-year evaluation of N delivery methods for stocker cattle grazing annual ryegrass, impacts of interseeded clover on botanical composition of pastures and on forage dry matter (DM) mass, in vitro DM digestibility (IVDMD), and crude protein (CP) concentration were determined. Treatments included 1) annual ryegrass fertilized at the recommended rate of N (112 kg N ha-1) in split application (NFERT), 2) crimson clover interseeded into annual ryegrass that received half the recommended rate of N (56 kg N ha-1; CC), and 3) arrowleaf clover interseeded into annual ryegrass that received half the recommended rate of N (56 kg N ha-1; AC). The study lasted 140 days from 14 Dec. 2015 to 11 May 2016. Mean forage mass (P < 0.001) was greatest for NFERT (860 kg ha-1) pastures, intermediate for CC (777 kg ha-1), and least for AC (627 kg ha-1) pastures. Clover percentage within pastures over the grazing season was greatest (P < 0.001) for CC (194 g kg-1) and did not differ between AC (10 g kg-1) and NFERT (0.00 g kg-1). Crude protein concentration for NFERT (137 g kg-1) and CC (155 g kg-1) did not differ, but both were greater (P < 0.013) than AC (128 g kg-1). In vitro DM digestibility was not impacted by treatment (P = 0.77). There was a decrease (P < 0.001) in IVDMD as the grazing season progressed from 946 g kg-1 in Dec to 894 g kg-1 in Jan, 854 g kg-1 in Feb, 891 g kg-1 in March, 843 g kg-1 in April, and 715 g kg-1 in May. Results are interpreted to mean that interseeded CC may provide CP and IVDMD like that of N-fertilized annual ryegrass, but with reduced forage mass, and greater CP and IVDMD than AC.