Ruminant Nutrition: Calves and Heifers

摘要

The effect of replacing 35% of milk protein by vegetable protein in milkreplacers (MR; 24:18% CP:EE) to young calves in an intensive rearingsystem was evaluated. Forty-eight Holstein male calves (41 ± 8 kg ofBW; 3–5d old), were blocked by BW and birthdate, and randomly assignedto 4 treatments (Trt): (1) 100% milk protein (MP), (2) 65% MP+ 35% micronized soybean meal (MS), (3) 65% MP + 35% wheat gluten(WG), or (4) 65% MP + 35% mixed 50:50 MS and WG (SW), offeringMR at 20% of BW, 12.5% of DM, twice daily, weaning at d 60.Water and starter (21% CP, since d 21) were offered ad libitum. Intakeand BW were recorded daily and weekly, respectively. Total feces werecollected from each calf on d 14–18 (digestibility); blood samples weretaken at d 23 and 51 (glucose and insulin). All variables were analyzedusing a mixed model. Intake, BW, ADG, feed efficiency (FE), glucose,and insulin were analyzed as repeated measures over week (Wk). Therewas no Trt effect on MR intake (937 ± 10.9 g DM/d; P = 0.40), starterintake (390 ± 31.0 g DM/d; P = 0.28), ADG (738 ± 30.0 g/d; P =0.95), final BW (85.9 ± 1.8 kg/d; P = 0.95), and FE (635 ± 24.0 g/d;P = 0.54). Replacing 35% of MR protein by MS or WG decreased DMand CP digestibility, but this was not observed when 50:50 mix of MSWGwas used, consuming calves on SW more digestible CP than MP andMS. We found a treatment effect on insulin and insulin to glucose, butnot on glucose (Table 1). It is possible that WG and SW affected insulinresponsiveness, but more information is needed to confirm it. Therefore,replacement up to 35% of MR protein by a 50:50 mix of MS-WG allowsto achieve similar digestion and performance than MR with 100% of MP.