Citrus meal as an energy supplement for dairy cows

Abstract

Nine cows in each of four treatment groups consumed an estimated 70% of metabolizable energy requirements as hay and an estimated 30% of metabolizable energy requirements as a supplement consisting of either 1. 3.9 kg rolled barley, 2. 0.7 kg citrus meal and 3.2 kg rolled barley, 3. 1.9 kg citrus meal and 2.0 kg rolled barley or 4. 3.4 kg citrus meal. Milk production showed no consistent response to changes in the proportions of citrus meal and rolled barley in the ration. Production of fat, solids-not-fat and protein were similar for all treatments. Milk solids-not-fat concentrations were lower (P < 0.05) from cows consuming 1.9 or 3.4 kg of citrus meal (87.5 and 85.9 g L-1, respectively) compared with those of cows consuming 0 or 0.7 kg of citrus meal (90.0 and 91.0 g L-1, respectively). Milk protein concentrations were also lower (P < 0.05) from cows consuming 1.9 or 3.4 kg of citrus meal (30.8 and 30.9 g L-1, respectively) compared with those of cows consuming 0 or 0.7 kg of citrus meal (33.1 and 34.8 g L-1, respectively). Organoleptic gradings showed that the cream from cows fed 3.4 kg of citrus meal was abnormal in flavour compared with cream from cows fed no citrus meal. Milk fat from cows fed 3.4 kg of citrus meal compared with that from cows not fed citrus meal contained more C18:1 fatty acid (1 8.4 and 15.2%, respectively), less C12 fatty acid (4.1 and 4.9%, respectively) and less C8 fatty acid (1.7 and 1.8%, respectively). Citrus meal can replace up to 2 kg of rolled barley on a dry matter basis in dairy concentrate mixtures without any detrimental effect on milk production, cow liveweight or flavour of the milk. However, citrus meal is not a suitable energy substitute for cereal grains in concentrate mixtures fed primarily to increase the solids-not-fat or protein content of milk.