This study was designed to substantiate the contribution of increasing solid feed intake (SF) to protein and energy supply of veal calves. Due to potential interactions between milk replacer and solid feed, occurring either at the level of digestion or post-absorptive, this contribution may differ from that in ruminants exclusively fed on concentrates and roughage. To this end, 48 Holstein Friesian male calves (55 kg, SD: 2.1 kg) were divided over 16 groups of 3 calves each. Groups were assigned to one of 4 solid feed intake levels: 0, 9, 18, or 27 g DM of SF kg BW-0.75 d-1. Solid feed consisted of 25% chopped wheat straw, 25% maize silage and 50% concentrates on a DM basis. All calves received 40.7 g DM milk replacer kg BW-0.75 d-1 during the experimental period. Groups were housed in respiration chambers during the 4-d experimental period, at an average BW of 164 kg (SD: 10.3 kg). Within chambers, calves were housed individually on metabolic cages to allow quantification of nitrogen balance. Data were analyzed using regression procedures with SF intake related parameters as independent variables. Preliminary results show that SF0 calves (exclusively milk replacer) retained 241 kJ kg BW-0.75 d-1 at an intake of 880 kJ kg BW-0.75 d-1. The incremental efficiency with which energy from SF ingested was retained was 0.33 (P <0.05). The incremental efficiency with which digestible energy from SF was retained was 0.53 (P <0.05). SF0 calves retained 0.62 g N kg BW-0.75 d-1 at an intake of 1.38 g N kg BW-0.75 d-1. The incremental efficiency with which N from SF ingested was retained was 0.74. Surprisingly, the efficiency of N retention (% of intake) increased with increasing N from SF by 0.35% per g N (P <0.05). With increasing SF intake, there was a substantial shift in N excretion from urine to feces (P <0.05). In conclusion, results show that in veal calves, efficiency of N utilization from SF (fed on top of a milk replacer diet) is markedly higher when compared with N utilization of milk replacer. Interactions between SF and milk replacer, such as an increased recycling of urea-N, may be involved.
|Title of host publication||2011 annual Meeting abstracts, ADSA/ASAS New Orleans, Louisiana, USA, 10 - 14 July, 2011|
|Publication status||Published - 2011|
|Event||ADSA/ASAS New Orleans, Louisiana - |
Duration: 10 Jul 2011 → 14 Jul 2011
|Conference||ADSA/ASAS New Orleans, Louisiana|
|Period||10/07/11 → 14/07/11|