Phytogenic Feed Additives Pre- and Post-Calving and Effects of Substituting DDGs with Soybean Meal on Protein Metabolism in Beef Cattle

The objective of these studies was to evaluate nutritional strategies to improve beef cattle productivity through targeted supplementation and protein source manipulation. The first study investigated the effects of a phytogenic supplement (PHYT; a blend of turmeric, capsicum, and black pepper oleoresin) on colostrum yield and composition, calf passive immunity, and cow–calf performance. Twenty-three Angus-based cows were assigned to either a control group or received 250 or 500 mg/head/day of PHYT from 30 days pre-calving to 60 days post-calving. Supplementation with PHYT linearly increased colostrum fat and calf serum IgA concentrations. Milk fat, calf serum IgG, and colostrum IgM tended to increase with PHYT. Calf average daily gain (ADG) responded quadratically, with the 250 mg dose yielding the highest gain. These findings suggest that PHYT may improve colostrum quality and enhance calf immunity and growth in cow–calf systems. The second and third studies evaluated the impacts of replacing dried distillers grains with solubles (DDGS) with soybean meal (SBM) on ruminal protein degradability, ammonia and volatile fatty acid (VFA) concentrations, as well as nutrient and amino acid (AA) flow to the small intestine, digestibility, and overall nitrogen (N) utilization. Four Red Angus steers with ruminal, duodenal, and ileal cannulas were used in a 4 × 4 Latin square. Diets contained 0%, 50%, 75%, or 100% SBM in place of DDGS. Replacing DDGS with SBM had no effect on ruminally degradable protein or most AA digestibility. Ammonia and VFA concentrations were highest with 75% SBM, suggesting improved microbial fermentation. Lysine digestibility increased with SBM inclusion. Nitrogen intake and fiber digestibility showed non-linear patterns across treatments. Most AA reached the small and large intestines similarly across diets, and SBM and DDGS supplied comparable metabolizable protein. Collectively, these studies show that phytogenic supplements may enhance calf performance through improved colostrum quality, while SBM can effectively replace DDGS in finishing diets without compromising rumen health or protein supply. These findings support the use of botanical additives and SBM to optimize efficiency in beef cattle systems.