Effect of fibrous by-products on production and ruminal fermentation in lactating dairy cows.
Lactating dairy cows were used in experiments to determine the effects of feeding a combination of fibrous by-products to replace a portion of alfalfa hay or grain. Cows were fed a control diet, consisting of alfalfa hay, corn, soybean meal, and corn silage or one of four treatment diets. In these diets, a combination of soy hulls, corn gluten feed, and wheat midds replaced approximately 30 or 60% of alfalfa hay or 25 or 50% of corn and soybean meal. A 56-d production study used 50 midlactation dairy cows in a randomized complete block design. No differences in milk production or composition among treatments were measured, except for the diet in which 60% of the alfalfa hay was replaced with fibrous by-products. Cows fed this diet had a significantly lower percentage of milk fat compared with other treatments. A fermentation study used five fistulated, multiparous lactating dairy cows in a 5 x 5 Latin square design. Cows were fed one of the five experimental diets used in the production study during five consecutive 14-d periods. Rumen acetate to propionate ratio was highest for the control and 50% concentrate replacement diets (3.27) and lowest for the 60% hay replacement diet (2.78). This shift in ruminal volatile fatty acid profile corresponded to the change in milk fat percentage, measured during the production study. A mixture of fibrous by-products fed as an alternative to hay or grain ingredients could potentially decrease feed costs without a resultant decrease in milk production by mid-lactation dairy cows.
Mowrey
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A
Department of Animal Science, University of Missouri, Columbia 65211, USA.
Ellersieck
M R
MR
Spain
J N
JN
D000085:Acetates / Q000378:metabolism; D000818:Animals; D002417:Cattle; D004043:Dietary Fiber / Q000008:administration & dosage*; D005260:Female; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D007774:Lactation; D008055:Lipids / Q000032:analysis; D000455:Medicago sativa; D008892:Milk / Q000737:chemistry; D011422:Propionates / Q000378:metabolism; D012417:Rumen / Q000378:metabolism*; D012820:Silage; D013025:Glycine max; D003313:Zea mays
D000085:Acetates; D004043:Dietary Fiber; D008055:Lipids; D011422:Propionates