title: Effect of protein source and soluble carbohydrate addition on rumen fermentation and lactation performance of Holstein cows.
abstract: Rumen in vitro and in vivo experiments were conducted to evaluate the effect of rumen undegradable protein and soluble carbohydrates on rumen ammonia N release and lactation performance of Holstein cows. In the in vitro experiment, freeze-dried annual ryegrass (Lolium multiflorum, LAM) pasture was supplemented 1:1 with ground corn-based grain supplements containing expeller or solvent soybean meal with sucrose or lactose supplements at 0, 2.5, or 5% of dry matter (DM). The ammonia release rate was slower with expeller compared with solvent soybean meal-supplemented diets. Sucrose supplementation at the 5% level lowered rumen ammonia concentrations, but lactose-fortification of grain supplements was without effect. In the in vivo study, 32 multiparous Holstein cows were blocked according to milk yield and randomly assigned to corn-based grain supplements containing 1) solvent soybean meal, 2) solvent soybean meal + 5% sucrose supplement, 3) expeller soybean meal, or 4) expeller soybean meal + 5% sucrose supplement. Grain supplements and fresh annual ryegrass were component fed at approximately a 1:1 grain to forage ratio (DM basis). Forage DM intake was higher for cows receiving solvent soybean meal supplemented grain supplements than those receiving expeller soybean meal (12.2 +/- 2.1 vs. 11.4 +/- 2.2 kg/d), but total DM intake was similar for all diets (22.8 +/- 2.9 kg/d). Fat-corrected milk yield was similar for all diets averaging 37.5, 38.2, 39.1, and 37.6 kg/d for diets 1 to 4, respectively. Rumen fermentation, milk urea nitrogen, and body condition were unaffected by supplements; however, cows fed grain supplement 1 utilized dietary energy more efficiently than cows offered the other dietary treatments. High dietary crude protein concentrations may have limited lactation response to rumen undegradable protein and sugar.
authors.affiliation: Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Franklinton 70438, USA. memccormick@agctr.lsu.edu
authors.forename: M E
authors.initials: ME
authors.lastname: McCormick
authors.forename: D D
authors.initials: DD
authors.lastname: Redfearn
authors.forename: J D
authors.initials: JD
authors.lastname: Ward
authors.forename: D C
authors.initials: DC
authors.lastname: Blouin
mesh_terms: D000641:Ammonia / Q000097:blood*; D000818:Animals; D002417:Cattle / Q000502:physiology*; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004044:Dietary Proteins / Q000494:pharmacology*; D005260:Female; D005285:Fermentation / Q000187:drug effects*; D007774:Lactation / Q000187:drug effects* / Q000502:physiology; D007785:Lactose / Q000494:pharmacology; D008892:Milk / Q000737:chemistry; D012417:Rumen / Q000378:metabolism*; D012434:Secale; D013025:Glycine max; D013395:Sucrose / Q000494:pharmacology; D014508:Urea; D003313:Zea mays
chemical_list: D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D013395:Sucrose; D000641:Ammonia; D014508:Urea; D007785:Lactose