Abomasal protein infusions for growing steers fed corn grain rations

Area of Science:

• Animal Nutrition
• Ruminant Physiology
• Nutrient Metabolism

Background:

• Growing steers fed urea-supplemented corn diets may have nutrient limitations.
• Postruminal nutrient supply is crucial for optimizing growth performance.

Purpose of the Study:

• To evaluate the impact of abomasal casein infusion on nitrogen balance in steers.
• To determine if feed intake level affects the response to postruminal protein supplementation.
• To assess the benefit of supplemental abomasal urea on nitrogen retention.

Main Methods:

• Five growing steers received abomasal infusions of casein (0-120 g) in a 5x5 Latin square.
• A second study used four steers to compare ad libitum vs. limit-feeding with casein infusion.
• A third trial infused urea or dextrose into steers to assess nitrogen retention.

Main Results:

• Abomasal casein infusion did not consistently increase nitrogen retention.
• Nitrogen retention tended to increase with urea infusion.
• The benefit of casein infusion on nitrogen retention was potentially greater with limit-feeding.

Conclusions:

• Nitrogen balance in young growing steers fed a urea-supplemented corn diet is likely limited by energy, total nitrogen, or other nutrients, not postruminal amino acids.
• Supplemental postruminal protein is unlikely to be beneficial under these feeding conditions.