Use of Heating Methods and Xylose to Increase Rumen Undegradable Protein of Alternative Protein Sources: 2) Cottonseed Meal

Abstract

The ruminal kinetics of protein sources may be changed by heat and sugar treatments. Thus, these processing methods may be used as alternatives to increase beef-cattle diets’ rumen undegradable protein (RUP). We aimed to evaluate the effects of processing cottonseed meals with autoclave, conventional, and microwave ovens, with and without using xylose, on the ruminal kinetics degradation parameters and intestinal digestibility (ID). In situ studies were conducted, and each sample was incubated in the rumen to determine dry matter (DM) and crude protein (CP) rumen degradation kinetics. In vitro studies were also conducted to evaluate ID. The control treatment had a greater soluble fraction for DM and CP than processed cottonseed meals (p < 0.05). The addition of xylose decreased both DM and CP water-soluble fractions (fraction A) of cottonseed meal heated in a conventional oven (p < 0.05). Compared to the control, we observed a decrease in effective degradability and increased RUP for all processed methods (p < 0.05). Furthermore, conventional and microwave ovens showed greater ID than the control. Moreover, xylose-treated groups heated in the autoclave and conventional ovens had greater ID than xylose-untreated cottonseed meal. Under these experimental conditions, cottonseed RUP was increased by the evaluated processing methods.

Keywords: beef cattle; protein degradation; protein feedstuff; ruminal degradation.

Figure 1

Effects of autoclave heating and xylose treatment on dry matter effective degradability (a), ED, rumen undegradable protein (b), RUP, and intestinal digestibility (c) of cottonseed meal. ED = A + [B × kd/(kd + kp) × e^−kt] [28]; RUP = B × [kp/(kp + kd)], where A is the water-soluble fraction, g/kg; B is the potentially degradable water-insoluble fraction, g/kg; kd is the degradation rate of fraction b, h⁻¹; t is time, h; and kp is the rumen passage rate of 0.074 h⁻¹ [28].

Figure 2

Effects of conventional-oven heating and xylose treatment on dry matter effective degradability (a), ED, rumen undegradable protein (b), RUP, and intestinal digestibility (c) of cottonseed meal. ED = A + [B × kd/(kd + kp) × e^-kt] [28]; RUP = B × [kp/(kp + kd)], where A is the water-soluble fraction, g/kg; B is the potentially degradable water-insoluble fraction, g/kg; kd is the degradation rate of fraction b, h⁻¹; t is time, h; and kp is the rumen passage rate of 0.074 h⁻¹ [28].

Figure 3

Effects of microwave-oven heating and xylose treatment on dry matter effective degradability (a), ED, rumen undegradable protein (b), RUP, and intestinal digestibility (c) of cottonseed meal. ED = A + [B × kd/(kd + kp) × e^−kt] [28]; RUP = B × [kp/(kp + kd)], where A is the water-soluble fraction, g/kg; B is the potentially degradable water-insoluble fraction, g/kg; kd is the degradation rate of fraction b, h⁻¹; t is time, h; and kp is the rumen passage rate of 0.074 h⁻¹ [28].