Steam-flaked lupins for preruminant calf rations

Steam-rolled lupins were studied as a cheaper alternative to complex and expensive commercial calf rations for rearing dairy calves. Four diets were fed to 4 groups of 6-8 calves: diet 1, 100% commercial pelletted calf ration (CR), 0% steam-flaked lupins (SFL); diet 2, 67% CR, 33% SFL; diet 3, 33% CR, 67% SFL; and diet 4, 100% SFL. A multimineral salt block and fresh water were available. Calves received milk-replacer (MR) in week 1, MR plus experimental diets in weeks 2-5, then experimental diets plus a small amount of straw in weeks 6-10. Calves grazed fresh pasture in weeks 11-15. Blood and rurnen contents were sampled in weeks 2 (blood only) 4,6 (diets 1-4), 8 and 10 (diets 1-3). In weeks 2-5, calves fed diet 4 ate less than calves fed diets 1, 2 and 3 (SFL 0.38 v. 0.50 kg dry matter (DM)/day, MR 0.47 v. 0.49 kg DM/day; P<0.05), grew less rapidly (0.58 v. 0.66 kg/day, not significant) and lost appetite in weeks 5-7. Feeding diet 4 was abandoned and CR, barley and hay were fed in weeks 8-10. In weeks 6-10, calves ate 2.49 kg DM/day of diets 1, 2 and 3 and grew 0.99 kg/day. Growth rates did not differ, at 0.59 kg/day in weeks 11-15; thus calves fed diet 4 seem to have sustained no permanent injury. Plasma glucose was higher in calves fed diet 4 in week 6 (P<0.05) but otherwise did not differ between diets or ages. Ruminal volatile fatty acids differed between diets only in week 6, when diet 4 resulted in a lower concentration than diets 1, 2 and 3 (95 v. 118 mmol/L), with 54.6 v. 49.9% acetic, 31.0 v. 34.1% propionic, and 8.0 v. 10.7% butyric acids. Plasma acetate increased steadily from 0.23 mmol/L at week 2 to 0.58 mmol/L at week 10 (P<0.05), with no difference between diets. We conclude that SFL can be a satisfactory component of the diet of young calves at up to 67% of the ration, producing calves with sufficiently developed ruminal digestion to permit unsupplemented grazing after 10 weeks of feeding.