Prediction of voluntary intake of conserved forages by cattle and sheep from degradability characteristics determined using synthetic fibre bags in sheep

Extract

Hovell et al. (1986) proposed that degradation characteristics of forages, as measured in nylon bags, may have useful application in predicting voluntary intakes. They reported intakes of four hays by sheep were more closely related to the potential degradability of forage dry matter (DM) than to in vivo The present work was undertaken to examine these relationships with forages and with both young growing cattle and sheep.

Seven forages were prepared with the objective of providing material wide range of voluntary intake. The forages were:

• (i)WS, wheat straw

• (ii)AWS, round-baled WS wrapped in 4 layers of overlapping plastic sheet (Silawrap; Volac Ltd), injected with 32% aqueous ammonia at the rate of 40kg/1000kg DM

• (iii)H1, first cut ryegrass hay

• (iv)H2, second cut ryegrass hay from the same field as (iii)

• (v)S2, 50% DM silage, baled and wrapped with Silawrap, prepared from the same crop as H2

• (vi)ES2, the same crop as S2 sprayed with a mixed enzyme preparation (Deezyme, Finnish Sugar Company Ltd.) at 0.81/tonne immediately before baling and wrapping with Silawrap

• (vii)AS2, S2 treated with aqueous ammonia in the wrapped bale as for AWS. All forages were fed in the long form except WS which was coarsely chopped through a straw chopper without any retaining screen into approximately 7cm lengths.