[Urea utilization of growing lambs. 2. Growth experiments]

Area of Science:

• Animal Science
• Nutritional Biochemistry
• Agricultural Science

Background:

• Intensive lamb fattening requires optimizing feed rations for maximum performance.
• Understanding the impact of non-protein nitrogen sources like urea and fibrous roughages like straw is crucial for feed formulation.

Purpose of the Study:

• To evaluate the effects of urea and straw supplementation on the performance of lambs during intensive fattening.
• To determine the optimal inclusion levels of urea and straw for improved feed intake, energy utilization, and weight gain.

Main Methods:

• Two growth experiments were conducted with lambs in groups, varying urea (1-2%) and straw (20-30%) content in rations.
• Rations varied in dry matter (DM), energy (EFUcattle), and crude protein content (10.1-18.4%).
• Performance metrics including dry matter intake, energy utilization (EFUcattle/kg weight gain), and average daily weight gain were measured.

Main Results:

• Urea supplementation (1-2%) significantly increased daily weight gain by 24-26% compared to control groups.
• Rations containing urea showed improved dry matter, EFUcattle, and crude protein intake.
• Straw inclusion (20-30%) resulted in lower EFUcattle intake and increased energy expenditure per unit of weight gain, despite some variations in dry matter intake.

Conclusions:

• Urea supplementation is an effective strategy to enhance performance in intensive lamb fattening by improving nutrient intake and promoting weight gain.
• While straw can be included, its high inclusion level may negatively impact energy utilization and increase feeding costs.
• Optimizing urea and straw levels in feed rations is key for efficient and cost-effective lamb production.