Abstract

In pastoral systems, N intake by dairy cows generally exceeds requirements (Kolver 2000). Feeds with low N concentration can ‘dilute’ the amount of N eaten by grazing dairy cattle, and ultimately reduce N pollution of the environment. Use of fodder beet (FB) crop has increased substantially in New Zealand because of its high DM yield potential. Fodder beet also has low N content in the bulb of the plant (0.8 to 1.5% of DM; Heuzé et al. 2015) which is useful for diluting dietary N content. However, these low N concentrations could result in deficiencies of specific amino acids (AA), potentially limiting milk production. This paper reports the effect on plasma AA concentrations of partial replacement of ryegrass pasture with FB in the diet of lactating dairy cows. This information will provide insights on how low-N diets could impact nutrient supply to dairy cattle.

D, Pacheco, G Waghorn, and DE Dalley

Proceedings of the New Zealand Society of Animal Production, Volume 76, Adelaide, 62-64, 2016