G. Flachowsky et al., EVALUATION OF STRAW TREATMENT WITH AMMONIA SOURCES ON GROWING BULLS, Animal feed science and technology, 60(1-2), 1996, pp. 117-130
Energetical and ecological aspects of straw ammoniation were calculate
d based on five feeding trials with growing bulls consuming untreated,
ammonia or urea treated wheat straw. Dry straw was gased with ammonia
(3.0-3.2%) and wet straw (38.1-56.3% dry matter, DM) was treated with
urea (2.5-5% on DM base). In digestibility experiments with sheep and
feeding trials with 104 growing bulls fed treated and untreated straw
was compared. Bulls consumed 2 kg concentrate per day and untreated o
r treated straw ad libitum. In two experiments ammonia or urea treated
straw was given in adequate amounts to untreated straw (pair feeding)
. Based on the results of feeding trials energetic input (60 or 80 MJ
per kg N from ammonia or urea) and ecological output (NH3, CO2) were c
alculated, Ammoniation increased apparent digestibility of organic mat
ter of wheat straw from 43.9 to 52.7%, urea treatment enhanced it from
46.5 to 53.0% on average. Pair feeding of ammonia or urea treated whe
at straw resulted in an increase of daily liveweight gain amounting 69
and 55 g day(-1). Ad libitum intake of treated straw increased daily
weight gain with range of 75 to 290 g. Animal growth rate was used to
evaluate the different straw treatments with regard to the ammonia sou
rces. Between 0.8 and 7.0 kg body weight were produced per kg N added
to the straw due to higher digestibility and increased straw intake. A
ssuming a conversion rate of 5 kg grains for 1 kg beef, one kg N used
as fertilizer has at least to increase the yield of cereals in the ran
ge of 3.8 and 35 kg, otherwise the N-utilization on the field would be
less efficient. Low animal response to ammoniation of straw resulted
in high fossil energy needs per animal and high environmental pollutio
n. More dose-response trials are necessary to allow a better evaluatio
n of N-efficiency in straw treatment.