Optimizing nitrogen utilization in growing steers fed forage diets supplemented with dried citrus pulp

Area of Science:

• Animal Science
• Ruminant Nutrition
• Forage Utilization

Background:

• Dried citrus pulp (DCP) is a potential energy source for ruminants.
• Bahiagrass hay is a common forage, often deficient in nitrogen.
• Supplemental nitrogen (N) is crucial for optimizing ruminal function and animal performance.

Purpose of the Study:

• To compare the effects of different supplemental N sources (solvent soybean meal, expeller soybean meal, urea) on ruminal fermentation of DCP.
• To evaluate the impact of these N sources on the performance of growing steers fed DCP and bahiagrass hay.

Main Methods:

• Experiment 1: In vitro incubation of DCP with different N sources to measure fermentation parameters.
• Experiment 2: A 4x4 Latin square design with steers fed bahiagrass hay and DCP, supplemented with N from urea or soybean meals, measuring intake and digestibility.
• Experiment 3: Individual feeding trials with steers comparing DCP, DCP + urea, or DCP + soybean meal, assessing dry matter intake (DMI) and average daily gain (ADG).

Main Results:

• Nitrogen supplementation increased ruminally fermentable fractions, in vitro dry matter digestibility (IVDMD), pH, ammonia, and total volatile fatty acids (VFA).
• Soybean meal-based N supplements improved DM and N intake, and N and ADF digestibility compared to urea.
• Steers fed soybean meal supplementation exhibited greater DMI, ADG, and improved growth efficiency compared to urea.

Conclusions:

• Supplemental nitrogen is essential for optimizing ruminal function and performance in growing steers fed DCP and forage.
• Soybean meal as a nitrogen source enhanced diet digestibility and animal performance more effectively than urea.
• The choice of supplemental nitrogen source significantly impacts nutrient utilization and growth outcomes in ruminants.