Carbohydrate spectroscopic features of bio-oil co-products in relation to rumen degradation kinetics in ruminants

Abstract Text:

The objectives of this study were to investigate the carbohydrate structure makeup associated with dry matter (DM) rumen degradation kinetics of three commonly used bio-oil co-products in ruminants. Three bio-oil products (rapeseed meal, canola meal and soybean meal) from three different sources in both Canada and China were collected in 2014. The carbohydrate spectral features were investigated using attenuated total reflectance-Fourier transform infrared spectroscopy instrument. The rumen degradation kinetics was determined according to the in situ nylon bag method with 3 rumen cannulated lactating Holstein cows at Rayner Dairy Teaching and Research Facility, University of Saskatchewan, Canada. The PROC MIXED procedure of SAS 9.3 was used for spectral data and degradation kinetics data analyses. The PROC CORR procedure of SAS was used to investigate the relationship between carbohydrate structure makeup and metabolic characteristics. Significances were declared at P < 0.05.The results showed that the peak area intensities of structural carbohydrate related region and its multiple peaks height were all lower in rapeseed meal and canola meal compared to soybean meal (P < 0.05). The cellulosic compound related spectral region had lower peak area and peak height intensities in rapeseed meal and canola meal than soybean meal (P < 0.05). Additionally, structural carbohydrate to total carbohydrate ratio and cellulosic compound to total carbohydrate ratio were all lower in rapeseed meal and canola meal than soybean meal (P < 0.05). For in situ DM rumen degradation kinetics, rapeseed meal had significantly lower soluble fraction than soybean meal. Rapeseed meal and canola meal had significantly lower potentially degradable fraction and higher undegradable fraction in comparison with soybean meal (P < 0.05). Compared to soybean meal, rapeseed meal and canola meal had higher rumen bypass DM content, and lower rumen effectively degradable DM content. There is a close relationship between carbohydrate spectral parameters and nutrient metabolic characteristics. The peak area intensity of functional group such as structural carbohydrate, cellulosic compound related region and their ratio to total carbohydrate were all positively related with DM degradable fraction and negatively correlated with DM undegradable fraction (P < 0.05). In conclusion, canola meal genetically developed from rapeseed meal shares similar carbohydrate structure and nutrition availability with rapeseed meal. The unique carbohydrate molecular spectral bands in the mid-IR region are highly associated with the nutrient utilization of bio-oil co-products in ruminants.

Keywords:

 carbohydrate molecular structure; vibrational spectroscopic profiles, nutrient metabolic characteristics