Corn Steep Liquor and Fermented Ammoniated Condensed Whey as Protein Sources for Lactating Cows and Yearling Heifers Grazing Winter Native Range

Story in Brief Corn steep liquor (CSL) and fermented ammoniated condensed whey (FACW) were compared to cottonseed meal (CS1\I) as protein sources f())' wintering 6 I lactating first-calf Hereford heifers and 32 yearling HerefOl'd heifers on nati\'e range. Cattle were allotted by weight and individually fed 6 days per week fill' 12 weeks one of four protein treatments: negative control (I\C). positi\'e control (PC), CSL and FACW to provide .7. 1.5. 1.5 and 1.51b crude protein «;1') per day. respectively, to the lacating heifers and .2. .4. .4 and .4 Ib CP per da\'. respecti\'eIy. to the yearling heifers. CSM was supplied in the CSL and FACW treatmellls at the same level as in the negative control. Lactating heifers fed the I\C lost more (P<.005) weight and body condition (120 Ib and 1.6 units) than those fed the PC (45.8 Ib and .9 units). Weight and condition losses were similar (1'>.05) f(lr lactating heifers fed PC, CSL and FACW. Yearling heifers fed the NC lost more (P<.005) weight than those fed the PC (49.4 \'S 10.6 Ib). Yearling heifers fed CSL and FACW gained more (P<.005) weight than those fed the PC (17.6 and 9.3 vs 1O.6Ib). Feeding CSL resulted in significantly lower rumen pH, lower ruminal acetate and higher ruminal butyrate, isovalerate and caproate le\-els than did feeding either control. Supplementing with FACW produced significantly lower rumen pH, higher rumen ammonia and soluble carbohydrate levels. lower ruminal acetate, and higher ruminal propionate and butyrate concentrations than did either control supplement. In vitro ammonia concentrations fi))' FACW were similar at 1,2,4 and 8 hours incubation and were higher (I' < .05) than the CSL ammonia concentrations. Ammonia nitrogen, amino acid nitrogen and long chain polypeptide and protein nitrogen accounted for 13.3. 17.0 and 29.6 percent of total nitrogen, respectively. in CSL and 60.0, 7.0 and 13.2 percent of total nitrogen, respectively, in FACW. Corn steep liquor and FAC\\' appear to be effective protein sources for cows and heifers grazing winter native range.