Acid-base balance in ruminating calves given sodium hydroxide-treated straw

Area of Science:

• Animal Nutrition
• Comparative Physiology
• Ruminant Metabolism

Background:

• Understanding mineral and non-metabolizable base (NB) balance is crucial for ruminant growth.
• Alkali treatment of barley straw can alter its nutritional value and impact animal physiology.
• Assessing the renal control of acid-base and electrolyte status is vital in livestock feeding studies.

Purpose of the Study:

• To quantify non-metabolizable base (NB) balance and mineral retention in growing bull calves.
• To evaluate the effects of long-term alkali-treated barley straw on growth, mineral deposition, and acid-base status.
• To determine the renal capacity to manage excess mineral and NB loads from diet.

Main Methods:

• Whole-body mineral and non-metabolizable base (NB) balance studies were conducted in Holstein X Friesian bull calves.
• Animals were fed either standard barley straw (Group A) or alkali-treated barley straw (Groups B, C, D).
• Blood and urine acid-base and electrolyte parameters were monitored over a 105-day experimental period.

Main Results:

• Normal growth in Group A was associated with positive NB balance due to tissue deposition.
• Bull calves fed alkali-treated straw tolerated high dietary loads of NaOH or NaCl without significant acid-base or growth disturbances.
• Surplus minerals and NB were absorbed and excreted via increased urine volume, with efficient renal regulation of extracellular fluid.

Conclusions:

• Growing bull calves maintain positive NB balance through tissue deposition, primarily in the skeleton.
• Ruminants exhibit a remarkable capacity to adapt to alkali-straw feeding, managing excess mineral and NB loads through renal excretion.
• Efficient renal control is key to maintaining stable extracellular fluid composition and acid-base homeostasis despite dietary challenges.