Abstract

The nutritive value of perennial ryegrass (RG), low mass Matua prairie grass (LM) and high mass Matua prairie grass (HM) swards were measured during early spring, late spring, summer and autumn of 1987/88 and 1988/89. Pre-grazing herbage masses were approximately 3000, 4000 and 5500 kgDM/ha for RG, LM and HM swards, respectively. Lactating cows on a common herbage allowance (50 kg DM/cow daily), grazed the ryegrass and Matua swards at mean intervals of 25 and 35 d, respectively. Values for the concentration of N (% OM) and DMD in whole plants, average across all seasons, were (%N) 2.6, 2.5 and 2,3, and (% DMD) 71.4, 71.1 and 69.4, respectively, for RG, LM and HM. The values for HM were significantly lower than those for the other two treatments. Values for the concentration of N and DMD in green grass leaf were (%N) 3.4, 3.5 and 3.5, and (% DMD) 72.4, 71.9 and 71.5, respectively, for RG, LM and HM. There were no significant differences in % N between the three treatments; the differences in % DMD between RG and HM was significant. During the autumn in both years, the LM treatment had a higher value for DMD % than the RG treatment (by 3 to 6% units). These results indicate that even at high pre-grazing herbage masses (4-5 tDM/ha) Matua prairie grass plants maintained relatively high nutritive values in green leaf and stem.

JM, Kelly, BW McBridge, LP Milligan, and DR Waldo

Proceedings of the New Zealand Society of Animal Production, Volume 51, , 123-128, 1991