title: Feeding value of glycerol as a replacement for corn grain in rations fed to lactating dairy cows.
abstract: Growth of the corn ethanol industry has created a need for alternatives to corn for lactating dairy cows. Concurrent expansion in soydiesel production is expected to increase availability and promote favorable pricing for glycerol, a primary co-product material. The objective of this study was to determine the feeding value of glycerol as a replacement for corn in diets fed to lactating dairy cattle. Sixty lactating Holstein cows housed in individual tie stalls were fed a base diet consisting of corn silage, legume forages, corn grain, soyhulls, roasted soybeans, and protein supplements. After a 2-wk acclimation period, cows were fed diets containing 0, 5, 10, or 15% refined glycerol for 56 d. Cows were milked twice daily and weekly milk samples were collected. Milk production was 36.3, 37.2, 37.9, and 36.2 +/- 1.6 kg/d and feed intake was 23.8, 24.6, 24.8, and 24.0 +/- 0.7 kg/d for 0, 5, 10, and 15% glycerol treatments, respectively, and did not differ except for a modest reduction in feed intake during the first 7 d of the trial for 15% glycerol (treatment x time effect). Milk composition was not altered by glycerol feeding except that milk urea nitrogen was decreased from 12.5 +/- 0.4 to 10.2 +/- 0.4 mg/dL with glycerol addition. Cows fed diets containing 10 and 15% glycerol gained more weight than those fed rations containing 0 or 5% glycerol but body condition scores did not differ with glycerol feeding. The data indicate that glycerol is a suitable replacement for corn grain in diets for lactating dairy cattle and that it may be included in rations to a level of at least 15% of dry matter without adverse effects on milk production or milk composition.
authors.affiliation: Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA. sdonkin@purdue.edu
authors.forename: S S
authors.initials: SS
authors.lastname: Donkin
authors.forename: S L
authors.initials: SL
authors.lastname: Koser
authors.forename: H M
authors.initials: HM
authors.lastname: White
authors.forename: P H
authors.initials: PH
authors.lastname: Doane
authors.forename: M J
authors.initials: MJ
authors.lastname: Cecava
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D003404:Creatinine / Q000652:urine; D004032:Diet; D004043:Dietary Fiber / Q000008:administration & dosage / Q000378:metabolism; D004063:Digestion; D004435:Eating / Q000187:drug effects; D005260:Female; D005990:Glycerol / Q000008:administration & dosage*; D007774:Lactation / Q000502:physiology*; D008892:Milk / Q000737:chemistry; D009584:Nitrogen / Q000378:metabolism; D011687:Purines / Q000652:urine; D015430:Weight Gain; D003313:Zea mays
chemical_list: D004043:Dietary Fiber; D011687:Purines; D003404:Creatinine; D009584:Nitrogen; D005990:Glycerol; C030985:purine