In experiment two, investigated greater CP concentrations with soybean meal and blood meal each supplying 50% of the CP at 11, 14, 17, 20, 23, or 26% of the diet dry matter. The DMI of calves did not differ across the different CP concentrations, but DMI was 48% less during week one relative to week two. Crude protein intake increased from 265 to 738 g/d (0.58 to 1.63 lb/d), with only the 23 and 26% CP concentrations meeting the protein requirements of 525 lb calves trying to achieve a 3 lb/d ADG. Not surprisingly, ADG increased linearly with the 23 and 26% CP treatments having the greatest ADG during week one. Interestingly, G:F demonstrated a quadratic response where 17 and 20% CP treatments were greatest during week one and for ADG and G:F across the entire four week receiving period on average. Therefore, the results indicate that about 20% CP resulted in the best feedlot performance during the receiving period.
Experiment three investigated changing dietary CP concentrations after week one and week two when feed intake appeared to be the lowest. Crude protein concentrations were 23% for week one, 17% for week two, and 12.5% for week three. In addition, different feedstuffs were investigated to supply dietary protein, with either soybean meal, blood meal, corn gluten meal, or fish meal used. Feed intake was 40 to 48% less during week one compared with week two. The different protein sources did not result in any significant differences in feedlot performance during the four week receiving period. As long as metabolizable protein requirements are being met, a wide variety of protein sources may be used to meet dietary protein needs of newly received feedlot calves.
It is not uncommon for newly received feedlot calves to have feed intakes 0.5 to 1.5 % of their body weight during the first week. However, providing these stressed calves adequate energy and protein to meet their nutrient needs will improve their ability to increase their feed intake and combat potential illnesses. Providing calves a preconditioning period before feedlot entry can greatly reduce weaning stress, expose and acclimate calves to the feedstuffs used in feedlots, and accumulate energy reserves prior to transport, which will allow for an easier transition into the feedlot for newly received calves.
Source : msu.edu