Exogenous β-mannanase improves feed conversion efficiency and reduces somatic cell count in dairy cattle

Area of Science:

• Animal Science
• Nutritional Biochemistry
• Enzyme Technology

Background:

• Exogenous fibrolytic enzymes, such as β-mannanase, show potential for improving feed conversion efficiency (FCE) in livestock.
• While extensively studied in nonruminants, the effects of β-mannanase supplementation in ruminants, particularly dairy cows, require further investigation.

Purpose of the Study:

• To evaluate the impact of β-mannanase supplementation on nutrient digestibility, FCE, and nitrogen utilization in lactating Holstein dairy cows.
• To determine the optimal dosage of β-mannanase for improving dairy cow performance.

Main Methods:

• A 3×3 Latin square design was employed with 12 multiparous Holstein cows.
• Cows were fed a basal diet supplemented with three levels of β-mannanase: 0% (control), 0.1% (low supplement, LS), and 0.2% (high supplement, HS) of dry matter.
• Nutrient digestibility, feed intake, milk yield, milk composition, and nitrogen utilization were monitored over 18-day periods.

Main Results:

• The low supplement (LS) dose of β-mannanase (0.1% DM) reduced dry matter intake but increased milk produced per kg of dry matter intake by 90g.
• Somatic cell count (SCC) in milk was significantly lower in cows fed the LS diet.
• The high supplement (HS) dose did not yield significant changes in milk yield, DMI, SCC, or nutrient digestibility.
• Despite reduced crude protein digestibility with LS, nitrogen intake reduction led to similar fecal nitrogen excretion; however, milk protein nitrogen partitioning improved.

Conclusions:

• Supplementation of β-mannanase at 0.1% of dietary dry matter effectively improves feed conversion efficiency and reduces milk somatic cell count in lactating dairy cows.
• This dosage enhances milk production efficiency without adverse effects on milk yield, composition, or overall nitrogen excretion.
• Further research may explore higher dosages or different enzyme combinations for potentially greater benefits.