Comparison of total-mixed-ration and feed-to-yield strategies on blood profiles and dairy cow health.

Seventy-two Holstein-Friesian dairy cows were offered the same amount of concentrates over the first 140 days of lactation, by either a 'total-mixed-ration' or a 'feed-to-yield' strategy. The effects on blood profiles and cow health were examined. Cows on total-mixed-ration were offered a mixed ration comprising grass silage and concentrates (50:50 dry matter basis). Cows on feed-to-yield were offered a basal mixed ration (grass silage plus 6 kg concentrates/cow/day) plus additional concentrates via an out-of-parlour feeding system, calculated according to each individual cow's milk yield during the previous week. Cows on total-mixed-ration had a higher mean haemoglobin, packed cell volume and lymphocyte percentage. Concentrate allocation strategy had no effect on serum haptoglobin concentrations, interferon-gamma production of pokeweed mitogen-stimulated whole blood culture, the incidence of clinical or subclinical mastitis, lameness, respiratory or digestive problems and no strong relationships were identified between production parameters with serum metabolites, inflammatory and immune measures. This study demonstrates small physiological differences in metabolic parameters, and no differences in inflammatory or immune parameters, when allocating concentrates by total-mixed-ration or feed-to-yield.