AN EXAMINATION OF THE EFFECT OF METHOD AND LEVEL OF CONCENTRATE FEEDING ON MILK-PRODUCTION IN DAIRY-COWS OFFERED A GRASS SILAGE-BASED DIET

An experiment was conducted to examine the effect of method and level of concentrate feeding on milk production characteristics in dairy cow s offered a grass silage-based diet. Twelve treatments were used with 24 Holstein/Friesian dairy cows in a four-period change-over design ex periment. Treatments consisted of these methods of concentrate feeding (twice daily, four times daily or complete diet) and four levels of c oncentrate feeding (2, 4, 6 or 8 kg/day). Offering a complete diet sig nificantly reduced silage substitution rate (0.28 kg silage dry matter (DM) per kg concentrate DM) compared with concentrates offered twice daily (0.50 kg silage DM per kg concentrate DM; P < 0.01). Method of c oncentrate feeding had no significant effect on milk yield or milk fat concentration (P > 0.05), although the response in milk protein conce ntration to increased concentrate food level was significantly greater with twice and four times daily concentrate feeding than with complet e diet feeding (0.59, 0.56 and 0.44 g/kg per kg increase in concentrat e food level; P< 0.05). Increasing concentrate inclusion level signifi cantly reduced silage DM intake (P < 0.001) but significantly increase d (P < 0.001) total DM intake. Milk yield and milk protein concentrati on were significantly increased (P < 0.001) and milk fat concentration significantly reduced (P < 0.01) with increasing concentrate inclusio n level. Total ration apparent digestibility coefficients were unaffec ted (P > 0.05) by either method of feeding or concentrate inclusion le vel. However, modified acid-detergent fibre apparent digestibility dec reased significantly with increasing concentrate inclusion (P < 0.01). Results suggested that offering complete diets, with concentrates com prising on average 0.33 of total DM intake, increased both silage and total DM intake although this was not reflected in either increased mi lk yield or improvements in milk composition.