Evaluation of nutritive value and in vitro rumen fermentation gas accumulation of de-oiled algal residues

Background：Algae are widely recognized for their high oil content and for exponentially accumulating biomass with particular potential to provide single cell protein for human consumption or animal feed.It is believed that along with biodiesel from algae,the high protein de-oiled algal residue may become an alternative feed supplement option in the future.This study was conducted to investigate de-oiled algal residue obtained from the common Chlorella species,Thalassiosira weissflogii,Selenarstrum capricornutum,Scenedesmus sp.,and Scenedesmus dimorphus for assessment as potential feed supplements for ruminants by comparing with soybean（Glycine max） meal and alfalfa（Medicago sativa） hay.Results：With the exception of T.weissflogii,algal residue had higher concentrations of Cu,Zn,and Mn and lower concentration of Ca,Mg,and K than soybean meal and alfalfa hay.The algal residue CP（crude protein）concentrations ranged from 140 to 445 g/kg DM and varied among the de-oiled residues.In vitro rumen fermentation gas accumulation curves indicated that algal biomass degradation potential was less than that of soybean meal or alfalfa hay by up to 41.7%.The gas production curve,interpreted with a dual pool logistic model,confirmed that the fraction sizes for fast fermenting and slow fermenting of de-oiled algal residues were smaller than those in soybean meal and alfalfa hay,and the fermenting rate of the fractions was also low.Conclusions：Inferior in vitro rumen gas accumulation from the five de-oiled algal residues suggests that these algal byproducts are less degradable in the rumen.

Assessment of fodder quality of leaves of multipurpose trees in subtropical humid climate of India

The leaves of 12 species （Acacia auriculiformis, Albizzia procera, Dalbergia sissoo, Gliricidia maculata, Leucaena leuco- cephala, Samanea saman, Azadirachta indica, Eucalyptus hybrida, Gmelina arborea, Michelia champaca, Morus alba, and Tectona grandis） of Multipurpose trees and shrubs （MPTs） grown in the agroforestry arboretum were evaluated for their nutritional characteristics in terms of proximate composition, cell wall constituents, total tannins, major （Ca and P） and trace minerals （Fe, Cu, Zn, Mn and Co）, in vitro dry matter and organic matter digestibility （IVDMD and IVOMD） and metabolisable energy （ME） values. There were significant （P〈0.01） variations among MPTs for all parameters studied. The average values of （92.02±0.30）%, （16.00±0.74）%, （3.05±0.13）%, （18.97±1.07）%, （54.00±1.12）% and （7.98 ± 0.30）% （DM basis） were observed for OM （organic matter）, CP （crude protein）, EE （ether extract）, CF （crude fibre）, NFE （nitrogen-free extract） and total ash, respectively. Leguminous trees had high CP compared to nonleguminous ones （18.30% vs 13.70%）. The mean values for cell wall constituents viz., NDF （neutral detergent fibre）, ADF （acid detergent fibre）, hemi cellulose, cellulose and ADL （acid detergent lignin） were found to be （52.48±1.05）%, （31.72±0.97）%, （20.76±0.88）%, （16.97±0.70）% and （9.57±0.62）%, respectively. The total tannin contents averaged （4.22±0.32）%. The ratio of Ca to P was quite wider. The levels of Fe and Mn were adequate to rich in all the MPTs while many of the tree species possessed P, Cu, Zn and Co level below the critical limits for the animals. The average IVDMD and IVOMD values were found to be （48.96±1.30）% and （50.69±1.36）%, respectively. The ME value averaged （6.95i-0.11） MJ·kg-1 DM. The CP content had significant positive correlation with IVDMD, IVOMD and ME val- ues while NDF, ADF, ADL and total tannins showed negative correlations with these three parameters. Based on the results, Leucaena Leucocephala could be considered as good quality fodder as it had the highest level of IVDMD/IVOMD （65.20%/67.66%） and ME （7.95 MJ·kg-1 DM） while G. maculata, M. alba, A. indica, D. sissoo and S. saman were of medium type and rest of poor quality.