Effect of microwave treatment on lucerne fodder

Abstract

Preliminary research has suggested that in vitro dry matter disappearance of some poor-quality fodder materials can be improved by microwave treatment. A laboratory-scale experiment that treated 50-g samples of lucerne hay in a 750-W microwave oven for 0, 40 and 80 s revealed that dry matter percentage increased by 1.7% as microwave treatment time increased from 0 to 80 s. The in vitro dry matter disappearance increased by 14.9% as microwave treatment increased from 0 to 80 s; however, there was no significant change in crude protein due to excessive variability in the results. This experiment was followed up with a larger-sample experiment in which 25-kg bags of lucerne fodder were treated for 7.5, 15, 22.5 or 30 min in an experimental 6-kW microwave chamber. Dry matter percentage increased by 7.2% as microwave treatment time increased from 0 to 30 min. Microwave treatment significantly increased dry matter disappearance during the in vitro digestion study; however, there were no significant differences between the various microwave treatment times. The 15-min treatment resulted in the greatest increase in dry matter disappearance (5.9%). The crude protein retained in the digestion residues increased by 19.2% as microwave treatment increased from 0 to 30 min. These laboratory studies were followed up with an animal response study in which 22 12–14-month-old Merino wethers were randomly allocated into either a group receiving a maintenance ration of untreated lucerne or a group receiving the same weight of microwave-treated lucerne. The average weight of the control group fluctuated around their starting weight during the 5-week-long trial, as would be expected from feeding a maintenance ration. By the end of the trial their average weight was 0.4% higher than when they started. However the group being fed the microwave-treated lucerne gained 8.1% of their initial bodyweight by the end of the trial.

Applications of Microwave Heating in Agricultural and Forestry Related Industries

“…Small scale in vitro pepsin-cellulase digestion experiments [103], similar to the technique developed by McLeod and Minson [104,105], demonstrated that microwave treatment: increased dry matter percentage with increasing microwave treatment time; increased in vitro dry matter disappearance with increasing microwave treatment time; but had no significant effect on post-digestion crude protein content.…”

“…The sudden jump in the heating rate after some time of steady heating may be evidence of thermal runaway ( Figure 9). Observation of the treated chaff showed no signs of charring; however the chaff was dry and crisp [103]. The onset of thermal runaway dramatically increases the heating efficiency.…”

“…However the group being fed the microwave treated lucerne gained 7 % of their initial body weight in the second week of the trial and maintained this body weight until the end of the trial. Their finishing weight after 5 weeks was 8.1 % higher than their starting weight [103].…”

“…Some of these problems of material transparency during microwave treatment can be overcome by compressing the fodder, which increases its ability to absorb microwave energy ( Figure 14). Brodie et al [103] treated 25 kg samples of lucerne chaff in an experimental 6 kW microwave chamber [31]. The temperature in the air space at the top of the lucerne bags rose to 100 °C in ~12 min and fluctuated above 100 °C for the remainder of the treatment time ( Figure 15).…”

Microwave Heating in Moist Materials

“…Microwave energy has also been used to manage weeds and other soil born pathogens (Nelson, 1987;Bansal, 2006) and to treat various animal feeds to improve their digestibility (Sadeghi & Shawrang, 2006Brodie et al, 2010). Microwaves are commonly used to process ceramics (Takayama et al, 2005) and can be used to drill through ceramics and glass (Jerby et al, 2002).…”