Determination of the amount of wet corn gluten feed to include in Determination of the amount of wet corn gluten feed to include in diets for lactating dairy cows diets for lactating dairy cows

of the dry matter


Introduction
Wet corn gluten feed (WCGF) is a potential feedstuff for dairy cows located near a source.Data from studies conducted with feedlot steers suggest that it improves average daily gain and dry matter intake, reduces acidosis, and yields feed efficiency values comparable to those with corn.W et corn gluten feed is relatively low in starch (18 to 22% of dry matter, DM), and high in neutral detergent fiber (42% of DM), with a protein fraction that is very degradable (65%) in the rumen.Lactation diets formulated to complement these characteristics should optimize the use of WCGF.The objectives of our study were to evaluate the effects of WCGF on the performance of lactating dairy cows when it was substituted in the diet for a portion of the forage and corn grain and to determine the optimal amount of WCGF to include in diets for multiparous, lactating dairy cows.

Procedures
Twenty-four multiparous Holstein cows averaging 65 days in milk were used in six 4×4 Latin squares with 28-day periods.Cows were housed and fed in a tie-stall facility at the Kansas State University Dairy, Manhattan, KS, and were fed individually diets formulated to meet or exceed NRC (1989) nutrient requirements.Diets were formulated to be isocaloric and isonitrogenous with similar amounts of neutral and acid detergent fiber, rumen-undegradable protein (RUP), and DM.Alfalfa hay and corn silage were used as forages, and corn as the primary grain.Expeller soybean meal (Soybest, Grain States Soya, Delevan, KS), 48% solvent soybean meal, and blood meal were used to balance diets for RUP.Treatments were control (no WCGF) and WCGF at inclusion amounts of 20, 27.5, and 35% of diet replacing a mix of alfalfa hay, corn silage, and corn grain.
Diets were fed free choice as a total mixed ration and issued twice daily to ensure 10% orts.Daily milk production and feed intake were recorded, and milk samples (AM-PM composite) were collected weekly and analyzed for milk composition: milk protein, fat, lactose, solids-non-fat (SNF), milk urea nitrogen (MUN), and somatic cells (Heart of America DHI Laboratory, Manhattan, KS).Cows were weighed and scored for body condition at the beginning of the study and at the end of each 28-day period.Body weights (BW) were obtained immediately after the AM milking on 2 consecutive days, and the average was used for analysis.Blood samples were collected from the cooccygeal vein during the final week of each period, and the harvested plasma was frozen at -4°F until analyzed for glucose, urea nitrogen, and total alpha amino nitrogen (TAAN).

Results and Discussion
Cows fed WCGF produced more (P<0.01)milk and energy-corrected milk (ECM) than cows fed the control diet.Cows fed diets containing 20 and 27.5% WCGF (% of DM) consumed more (P<0.05)DM as a percentage of BW than cows fed the control or 35% WCGF diet.The resulting increase in milk yield can be explained partially by the increase in DM intake, but production efficiency (lb milk/lb DM intake) also improved in cows fed WCGF.Milk fat percentage was lower (P<0.05) in milk from cows fed 20 and 35% WCGF compared to controls.Cows fed WCGF produced more (P<0.01)milk protein, SNF, and lactose than cows fed the control diet, primarily because of the increase in milk yield.Cows fed 27.5 and 35% WCGF had greater (P<0.01)MUN than cows fed control or 20% WCGF.
Somatic cell count, BW, and body condition score were unaffected by dietary inclusion of WCGF.Plasma glucose, TAAN, and total triglycerides were similar among diets, but plasma urea nitrogen increased (P<0.05) when cows consumed WCGF.Fecal pH tended to be greater (P=0.06) for cows fed the 27.5 and 35% WCGF diets, whereas urine pH decreased (P<0.05) when WCGF was included in the diet.
In summary, WCGF substituted for a mix of alfalfa hay, corn silage, and corn grain in diets of multiparous Holstein cows increased ECM yield.Cows fed 35% WCGF (% of DM) were most efficient, but intake and ECM production data indicated that 27.5% WCGF (% of DM) is the optimum inclusion level.