Protein for calves on a limited milk-early weaning system

Area of Science:

• Animal Science
• Ruminant Nutrition
• Dairy Cattle Management

Background:

• Limited milk-early weaning programs are common for Holstein heifer calves.
• Optimizing calf starter rations is crucial for early growth and development.
• Understanding the impact of crude protein levels and sources is essential for efficient calf rearing.

Purpose of the Study:

• To evaluate the effects of different crude protein (CP) percentages and sources in pelleted calf starter rations.
• To determine the optimal CP level for Holstein heifer calves on a limited milk-early weaning program.
• To compare the efficacy of urea versus vegetable protein in calf starter rations.

Main Methods:

• Holstein heifer calves (n=10 per group) were fed five pelleted starter rations with varying CP (10%, 12.5%, 15%) and protein sources (vegetable protein, urea) from 3 days to 12 weeks of age.
• Rations were formulated to meet specific digestible protein:digestible energy ratios.
• Feed intake, average daily gain (ADG), and feed efficiency were analyzed, adjusting for birth weight and other factors.

Main Results:

• Calves fed 15% CP rations exhibited greater feed intake and ADG compared to those fed 10% or 12.5% CP rations.
• Feed efficiency from week 5 to 12 was improved with 15% CP rations compared to lower CP levels.
• No significant differences in feed intake, ADG, or feed efficiency were found between urea and vegetable protein sources.

Conclusions:

• Higher crude protein levels (15%) in pelleted starter rations positively impact growth performance in Holstein heifer calves.
• Crude protein content, rather than the source (urea vs. vegetable protein), appears to be the primary driver of performance in this study.
• Optimizing CP levels in starter rations is a key strategy for enhancing early development in dairy heifers.