title: Reducing nitrogen excretion and soybean meal use by feeding a lower rumen degradable protein balance and protected soybean meal to dairy cattle.
abstract: To reduce N pollution by dairy cows, two levels of rumen degradable protein balance (RDPB) and the use of protected protein sources were studied in two feeding trials. Trial 1 investigated if the effect of lowering the RDPB, at a constant DPI (digestible protein in the intestine) supply, could be compensated by using protected protein sources (formaldehyde treated (= formolated) soybean meal (FSBM) or a combination of FSBM and formolated rapeseed meal at a ratio of 60:40). Trial 2 studied if FSBM is as effective as soybean meal (SBM) at a low RDPB level. Each trial was set up as a Latin square design, with three treatments and three periods, involving 18 lactating Holstein cows. Reducing RDPB from about 150 g/d to below -40 g/d resulted in small negative effects on the milk production, independent of the protein source (protected or not). However, N excretion per kg fat and protein corrected milk (FPCM) and N efficiency were both improved. At a low RDPB level, the performance of FSBM (35.0 kg FPCM) was no better than after feeding a combination of FSBM and formolated rapeseed meal (34.7 kg FPCM). The use of FSBM (32.8 kg FPCM and 34.2% N efficiency) was as effective as SBM (32.5 kg FPCM and 34.2% N efficiency). As such, SBM use can approximately be halved by using FSBM, possibly in combination with locally produced rapeseed meal.
authors.affiliation: Institute for Agricultural and Fisheries Research (ILVO), Animal Sciences Unit, Belgium. sam.decampeneere@ilvo.vlaanderen.be
authors.forename: Sam
authors.initials: S
authors.lastname: De Campeneere
authors.forename: Johan L
authors.initials: JL
authors.lastname: De Boever
authors.forename: José M
authors.initials: JM
authors.lastname: Vanacker
authors.forename: Daniël L
authors.initials: DL
authors.lastname: De Brabander
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000502:physiology*; D003612:Dairying; D004032:Diet / Q000662:veterinary*; D004044:Dietary Proteins / Q000378:metabolism; D005260:Female; D009584:Nitrogen / Q000737:chemistry / Q000378:metabolism*; D012417:Rumen / Q000378:metabolism; D013025:Glycine max / Q000737:chemistry / Q000378:metabolism*
chemical_list: D004044:Dietary Proteins; D009584:Nitrogen