Supplemental energy and extruded-expelled cottonseed meal as a supplemental protein source for beef cows consuming low-quality forage

doi:10.2527/jas.2008-1605

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Supplemental energy and extruded-expelled cottonseed meal as a supplemental protein source for beef cows consuming low-quality forage¹

S. J. Winterholler^*, D. L. Lalman^*^,2, M. D. Hudson^* and C. L. Goad

^* Department of Animal Science, and Department of Statistics, Oklahoma State University, Stillwater 74078

² Corresponding author: david.lalman{at}okstate.edu

Three experiments were conducted to evaluate the efficacy ofsupplemental energy and extruded-expelled cottonseed meal (ECSM;30.6% CP; 44% NDF, 10.2% fat; DM basis) as a protein supplement(SUP) to spring-calving beef cows (n = 96; 535 kg initial BW;5.4 initial BCS) consuming low-quality forage during late gestationand early lactation. Supplementation of ECSM was compared with2 traditional cottonseed meal-based SUP. For all experiments,SUP provided equal CP. On a DM basis, SUP included 1) a blendof 76% wheat middlings and 18% solvent-extracted cottonseedmeal (WMCSM); 2) solvent-extracted cottonseed meal (CSM); and3) delinted, extruded-expelled cottonseed meal (ECSM). In Exp.1, cows were individually fed SUP 3 d/wk until calving and 4d/wk during lactation; total SUP period was 95 d. Tall-grassprairie hay (4.4% CP; 74% NDF; DM basis) was provided duringthe SUP period. Changes in cow BW during gestation (P = 0.23),over the SUP period (P = 0.27), and over the 301-d experiment(P = 0.56) were similar. Changes in BCS were similar duringgestation (P = 0.78), over the SUP period (P = 0.95) and overthe 301-d experiment (P = 0.37). Calf birth weights (P = 0.21)and BW at weaning (P = 0.76) were not different. Percentageof cows exhibiting luteal activity at the beginning of breedingseason (P = 0.59), AI conception rate (P = 0.71), and pregnancyrate at weaning (P = 0.88) were not different. In Exp. 2, 18cows in early lactation from Exp. 1 were used to determine theeffect of SUP on hay intake and digestion. Hay intake tended(P = 0.10) to be greater for CSM than ECSM. Intake of OM andDM was greater for WMCSM (P $≤$ 0.02) compared with CSM and ECSM;likewise, digested DMI and OM intake were greater (P $≤$ 0.02)for WMCSM. Apparent total tract digestibility of crude fat wasgreater for ECSM than CSM (P = 0.03). In Exp. 3, cows (n = 20/treatment)of similar days postpartum were machine-milked to determineSUP effect on milk production and composition. Butterfat, protein,lactose, and milk urea N were not different (P > 0.10). Similarly,24-h milk production was not different (P = 0.25). Neither greaterenergy intake of cows consuming WMCSM nor greater fat intakeof cows consuming ECSM influenced cow performance measures orcalf weaning weight. Cow response to SUP with ECSM comparedwith traditional cottonseed meal-based SUP indicates that ECSMis a viable source of supplemental protein for beef cows consuminglow-quality forage.