Effects of dried citrus pulp on milk yield, milk composition and blood components of dairy cows

Twenty multiparous Friesian cows, 80–130 days postpartum, were allotted to two groups of ten cows, according to calving date, lactation number and daily yield, and assigned randomly to one of two diets in a crossover design experiment. The two experimental diets contained either 20% dried citrus pulp and 30% concentrate or 15% dried beet pulp, 8% ground maize and 27% concentrate, plus 50% maize silage (dry basis). The diets were offered individually, in tie-stalls, as total mixed rations in two equal amounts at 9:00 and 20:00 h to achieve ad libitum intakes. Dry matter, metabolizable energy and crude protein intakes, milk yield, milk protein content and yield, as well as content of milk lactose, total solids and non-fat solids were not significantly affected by the diet. In contrast, dried citrus pulp supplementation increased milk fat content (4.48 vs. 4.12%; P < 0.05) and milk fat yield (1.06 vs. 0.95 kg day−1; P < 0.05). No significant differences were observed in blood serum concentrations of glucose, total protein, albumin, globulin, urea, triglycerides, phospholipids, Na, K, Ca, P, Mg and Cl. In contrast, the serum concentration of cholesterol was higher (235 vs. 223 mg per 100 ml; P < 0.05) when the cows were fed on the diet containing dried citrus pulp.