Simulating Precision Feeding of High-Concentrate Diets with High-Fat Inclusion and Different Plant-Based Saturated, Unsaturated, and Animal Fat Sources in Continuous Culture Fermenters

Controlling dry matter intake (DMI) is one strategy to reduce feed costs and increase efficiency. Including fat at a high concentrate level can increase the energy density of diets fed to ruminants, thus reducing DMI further. Therefore, the objective of this study was to evaluate the effects on fermentation and nutrient digestion of including different fat sources when high-concentrate diets with high-fat inclusion are used under simulating precision feeding in continuous culture. We hypothesized that incorporating different fat sources into the aforementioned program can improve nutrient utilization without affecting rumen fermentation. Four treatments were randomly assigned to eight continuous cultures in a randomized complete block design and ran for two periods of 10 d. Diets included a high concentrate level (HC; 65% DM) with high-fat inclusion starting with a 3% basal level of fat in the diet as the control (0% added fat; CON) and 9% fat in the diet (6% added poultry fat, PF; 6% added coconut oil, CO; and (6% added soybean oil, SO). Data were analyzed using the MIXED procedure of SAS with repeated measures. The DM, OM, NDF, and ADF digestibility coefficients (dCs) were higher for PF and CO, followed by SO and then CON. Starch and FA dCs were higher for different fat sources than for the CON. The total VFA concentration was higher for CON. There was a reduction in acetate and propionate with different fat sources. The mean culture pH and NH₃N were the highest for CO, followed by PF, then SO, and CON. The protozoa population was higher for CON than for the other fat treatments, followed by CO, PF, and SO. These results suggest that simulated precision feeding using continuous culture fermenters with high-concentrate diets up to 65% and high fat up to 6% can improve nutrient digestion approximately to 15% with changes in fermentation rate and profiles.