Performance of young calves fed soybean protein replacers

Area of Science:

• Animal Nutrition
• Dairy Science
• Protein Metabolism

Background:

• Soybean protein is a potential alternative to milk protein in calf milk replacers.
• Understanding the digestibility and utilization of different soy protein sources is crucial for calf starter diets.

Purpose of the Study:

• To evaluate the efficacy of soybean protein concentrate and full-fat soy flour as protein sources in calf milk replacers.
• To assess the impact of calf age on the digestibility and nitrogen retention of soy-based milk replacers.

Main Methods:

• Two 12-week trials were conducted with Holstein calves.
• Calves were fed milk replacers with varying protein sources (milk protein, soy protein concentrate, full-fat soy flour, defatted soy flour) at different crude protein levels (26% and 30%).
• Apparent digestibility coefficients for dry matter, protein, fat, and ash, along with average daily nitrogen retention, were measured at different age periods.

Main Results:

• Soybean protein sources (soy protein concentrate and full-fat soy flour) showed lower apparent digestibility and negative nitrogen retention in younger calves compared to milk protein.
• Digestibility and nitrogen retention significantly improved for soy-based replacers as calves aged from 10-15 days to 30-35 days.
• Defatted soy flour exhibited the lowest digestibility and nitrogen retention across all measurements.

Conclusions:

• Calves demonstrate an improved ability to utilize soy-based milk replacers with increasing age.
• Soy protein concentrate and full-fat soy flour can be effectively used in calf milk replacers, particularly as calves mature.
• Further research may be warranted to optimize soy protein processing for younger calves.