Effects of Cassava Hay Supplementation on Antibacterial Activity of the Lactoperoxidase System in Raw Milk of Dairy Cows

Abstract

Sixteen multiparous cows in early-to-mid lactation (82.4±8.6 day in milk, DIM) were used in a completely randomized block design with repeated measurement to evaluate the effects of cassava hay (CH) supplementation on antibacterial activity of the lactoperoxidase system in raw milk. The cows were blocked into four groups based on DIM and previous milk yield. Each group was randomly fed dietary treatment twice daily for four months. Treatment diets were: T1) concentrate (control); T2) concentrate+1 kgCH/head/day; T3) concentrate+2 kgCH/head/day; and T4) concentrate+3 kgCH/head/day. The concentrate for each treatment was formulated to provide together with CH, a daily intake of 1,830-1,940 gm protein. The cows received 25 kg/head/day of ruzi grass silage. After a 14-d adaptation period, daily milk yield was recorded and the raw milk of the cows was collected every month and analyzed for lactoperoxidase and thiocyanate concentration, standard plate, coliform, psychrotrophic and thermophilic counts. Milk yield and milk lactoperoxidase concentrations were not affected by treatments (P>0.05). Thiocyanate concentrations were higher (P<0.01) for T2, T3 and T4 than for T1. Standard plate, coliform, psychrotrophic and thermophilic counts were lower in T2, T3 and T4 compared to T1. The results showed that supplementation of cassava hay to dairy cows increased the efficiency of antibacterial activity of the lactoperoxidase system in raw milk.