Effects of soybean oil or various levels of whole cottonseed on intake, digestibility, feeding behavior, and ruminal fermentation characteristics of finishing beef cattle

Abstract

Six rumen-cannulated Nellore steers (407 ± 24 kg initial body weight) were used in a 6 × 6 Latin square design experiment to evaluate the effects of soybean oil (SO) or various levels of whole cottonseed (WC) in finishing diets. Treatments consisted of five levels [0, 8, 16, 24, and 32% of dry matter (DM) basis] of WC in diets containing 80% concentrate and one diet formulated to contain a similar concentration of lipid (DM basis) as diet WC32 but without WC, rather using SO. Increasing levels of WC decreased the intake of DM, non-fibrous carbohydrate, and total digestible nutrients (linear; P ≤ 0.01), tended to decrease the intake of crude protein (linear; P = 0.10), but didn't affect the intake of neutral detergent fiber (P = 0.12). The intake of total fatty acids increased (linear; P < 0.01) due to the increasing levels of WC. The inclusion of SO also increased the intake of total fatty acids (P < 0.01) but did not affect (P ≥ 0.20) the intake of DM, crude protein and neutral detergent fiber compared with WC0. Increasing levels of WC decreased the total volatile fatty acids concentration (linear; P < 0.001). Feeding SO reduced the total protozoa account (P < 0.001) compared with WC0. Feeding SO did not affect the intake, nutrient digestibility, and the main ruminal characteristics compared with the control diet, therefore no positive effects of increasing dietary fat content from 3.2 to 7.8% with soybean soil on growth performance would be expected. The DM intake was dramatically decreased in response to the levels of WC, as well as the ruminal fermentation characteristics.