A SURVEY OF SILAGE QUALITY ON NORTHLAND DAIRY FARMS

Abstract

A survey was made on 31 dairy farms of the botanical and chemical composition of pasture being ensiled and of the chemical composition of the resultant silages. Despite the wide range in grass (37-100s) and legume (O-SO%) components, drymatter content (20-56v/o), soluble carbohydrate (4-19s) and neutral detergent fibre (NDF) (43-69%) contents, NDF was the only component significantly correlated with dry matter digestibility (range 53-76%) (r = -0.77; P > 0.01). Wilting time ranged from 2-47 hours except in seven of the silages which were not wilted. Four silages were not covered with polythene but were similar in chemical composition to other silages when sampled in summer. Phosphorus (P) (.lS-.42% DM) and nitrogen (N) (l.O-2.2% DM) in silage were below published requirements for cows in mid lactation in more than 75% of the silages. It is suggested that either or both of these minerals may limit milk production from cows fed a predominantly silage ration during summer. Ensiling of less-mature pasture is advocated to ensure a more digestible feed which is likely to contain adequate levels of P and N.