Effect of condensed molasses solubles on intake growth performance digestibility and certain rumen parameters of sheep

Abstract

With a shortage of, and an increase in the price of conventional feedstuff for livestock, combined with the restrictions on the disposal of by-products from industrial plants, this has lead to by-product materials being commonly used as raw materials in ruminant diets. Condensed molasses solubles (CMS) is a byproduct derived from the fermentation of molasses during the production of ethanol. In this trial sugarcane CMS was used to replace molasses in a high concentrate sheep ration. The experimental diets were based on an iso-nitrogenous and iso-energetic basis with only the inclusion levels of CMS differing between the diets. The treatments were 0% CMS (control), 4% CMS, 8% CMS and 12% CMS; thus the inclusion of CMS was 0%, 4%, 8% and 12% on an as is basis in the diets respectively. The control diet (0% CMS) contained no CMS but 8% molasses. Experiment 1, a 4 x 4 Latin Square design with four rumen cannulated Merino wethers was conducted to determine the effect of different inclusion levels of CMS on intake, apparent total tract digestibility, rumen fermentation, apparent nitrogen retention and microbial nitrogen production. Feed intake did not differ (P >0.05) between treatments. Organic matter digestibility was lower (P <0.05) in the 0% CMS and 4% CMS treatments compared to the 12% CMS treatment. Rumen fermentation, apparent nitrogen retention and microbial nitrogen production showed no differences (P >0.05) between treatments; however some experimental error may have influenced the microbial nitrogen production results. Experiment 2, a randomised complete block design with 200 South African Mutton Merino lambs (27.6 kg ± 4.8 kg) was conducted to access the effects of different inclusion levels of CMS on intake, growth performance and carcass characteristics of the lambs under practical feedlot conditions. The 0% CMS treatment had a lower (P <0.05) average daily gain and final live body weight compared to the 4% CMS treatment. The 0% CMS treatment had a higher (P <0.05) feed conversion ratio compared to the 4% CMS, 8% CMS and 12% CMS treatments. Feed intake did not differ (P >0.05) between treatments. The 0% CMS treatment also had lower (P <0.05) carcass traits compared to the 4%, 8% and 12% CMS treatments. One of the concerns with using CMS was the high levels of sulphur. Liver samples were taken and analysed for copper to determine if the sulphur had reduced the absorption of the copper in the body. The copper concentration in the livers of 0% CMS treatment was lower (P <0.05) than the 8% CMS treatment. All the treatments had copper concentrations that fell within the range of normal liver copper values, thus assuming that sulphur did not have an adverse effect. The results suggest that condensed molasses solubles can be included up to 12% on an as is basis to replace molasses in a high concentrate diet without having an adverse effect on intake, growth performance, digestibility and certain rumen parameters of sheep. Further research needs to be conducted into including CMS at higher levels.