AbstractA double-reversal experiment with 80-day periods, extending from day 26 to day 265 of lactation, was conducted with 2 groups of 10 cows each. The two treatments consisted of two different concentrate mixtures, one of which had a simple formula consisting of ground shelled corn, soybean-oil meal, fortified molasses, bonemeal, and salt, and was prepared at the Substation, while the other was a complex mixture obtained from a commercial source. Both mixtures contained nearly the same level of crude protein. Concentrate allowances were based upon the Maryland Standards. The remainder of the ration consisted of a moderate amount of sorghum silage, or occasionally green chopped grass, and low-quality pasture. The simple-concentrate mixture proved to be more palatable than the complex mixture. The lactational response obtained with the simple mixture as compared with the complex mixture was significantly (P < 0.01) greater in production of milk uncorrected for fat content, 28.2 vs. 27.1 pounds per day, though not significantly different in production of 4-percent fat-corrected milk nor in production of milk fat. The efficiency of utilization of the simple mixture was significantly, P < 0.05, better for the production of milk uncorrected for fat content, 55.3 vs. 56.8 pounds of concentrates per 100 pounds of milk produced, but not significantly better for the production of 4-percent fat-corrected milk. The cost of concentrates per 100 pounds of milk produced was $2.34 for the simple and $2.67 for the complex mixture. It is concluded that, under conditions of the present experiment, in which forage was limited in quantity and of only fair quality, a simple concentrate mixture formulated to supply digestible energy at a minimum cost is just as adequate nutritionally for lactating cows as a concentrate mixture containing a multitude of different ingredients and supplemented with minerals, vitamins, and antioxidants. It is further concluded that the use of such simple concentrate mixtures prepared at the dairy farm will result in a reduction in feeding costs, provided the operation is large enough to offset the cost of the required machinery. A possible alternative would be the commercial preparation by feed mills of simple concentrate mixtures which could be sold to dairymen at a lower price than the present complex commercial mixtures.
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