Changes in milk composition as affected by subclinical mastitis in goats

Area of Science:

• Veterinary Medicine
• Animal Science
• Dairy Production

Background:

• Subclinical mastitis (SM) is a prevalent udder infection in dairy animals.
• Understanding SM's impact on milk composition and yield is crucial for dairy goat farming.
• Previous research has focused on clinical mastitis, leaving gaps in knowledge regarding subclinical effects at the glandular level.

Purpose of the Study:

• To investigate the effects of subclinical mastitis (SM) on milk yield and curd yield (Yc) in dairy goats.
• To elucidate the underlying mechanisms of SM's impact on milk composition at the glandular level.
• To compare the effects of SM in goats with findings in sheep.

Main Methods:

• Twenty-five Israeli dairy goats were used, with one udder half naturally infected with coagulase-negative staphylococci and the contralateral half serving as a control.
• Milk yield, somatic cell count, N-acetyl-beta-D-glucosaminidase activity, and concentrations of lactose, casein, whey protein, albumin, Ca2+, and proteose peptone were measured.
• Plasmin and plasminogen activity, Ca2+ activity, and curd yield (Yc) were also assessed.

Main Results:

• Infected udder halves showed significantly lower milk yield and curd yield (Yc).
• Higher somatic cell counts and N-acetyl-beta-D-glucosaminidase activity were observed in infected glands.
• Lactose concentration was lower, while whey protein and albumin concentrations were higher in infected glands. Proteose peptone concentration was significantly increased.

Conclusions:

• Subclinical mastitis significantly impairs milk yield and curd yield in dairy goats through alterations in milk composition.
• Increased enzymatic activity and changes in protein and mineral profiles characterize SM at the glandular level.
• The findings provide insights into the mechanisms of SM's detrimental effects on milk production in goats.