Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)


Dairy Science


Short-term (6 to 13 wk) experiments indicated that adding small amounts of dried whey to the concentrate mix fed to lactating dairy cows increase d milk fat percentage, but decreased milk production. In order to determine if the increased fat percentage was a positive response to dried whey in the ration, or an artifact of drying off the cows early, 5% dried whey product (DWP) was included in the concentrate mix fed to 10 Holstein cows. All cows started on the experiment in their 4th wk postpartum and continued for the duration of their lactation. The DWP replaced a portion of the ground shelled corn, soybean meal, and dicalcium phosphate which was included in the control group's concentrate mix. Corn silage was f e d ad libitum, with alfalfa hay fed at 5 kg/hd daily, while concentrates were Jed at 1 kg/3 kg milk produced. There was no difference in actual milk production between the control and DWP-fed cows (21. 3 kg/day for both groups), but 4% fat-corrected milk and percent milk fat were higher for the DWP-fed cows (19.6 and 20.0 kg/day; 3.58 and 3.68%, respectively). Persistencies of actual production during the experiment (changes from 3rd wk postpartum) were slightly less for the DWP-fed cows, but persistency of 4% fat-corrected milk and milk fat yields were greater for the DWP-fed cows. Milk protein and solids-not-fat production and percentages of each were not affected by ration treatment. A subsequent 16 wk lactation trial was conducted to evaluate the effects of feeding large amounts of dried whey (65%) in the concentrate mix. Two groups of 10 Holstein cows which had been paired according to stage of lactation and lactation number were used. The dried whey replaced all of the ground shelled corn, dicalcium phosphate, trace mineralized salt, and portions of the rolled oats and soybean meal which were included in the control group's concentrate mix. The cows were fed corn silage ad libitum, 3.5 kg alfalfa hay/hd and grain (1 kg/3 kg milk produced) daily. Control cows produced more milk (25.3 and 22.1 kg/day, respectively) and more 4% fat-corrected milk (23.1 and 21.2 kg/day, respectively). However, cows fed dried whey had higher percent milk fat (3.77 and 3.46%, respectively). Persistencies of actual production during the experiment (changes from pretreatment) were less for the whey—fed cows, but persistency of fat-corrected milk was about the same due to an increase in milk fat percent from pretreatment for cows fed dried whey. Nitrogen components of milk were essentially the same for both groups with slightly less non-protein nitrogen in the milk of whey-fed cows. Rumen samples taken via stomach tube indicated higher molar percentages of butyrate and valerate, and lower values for acetate, propionate, and isobutyrate for whey-fed cows. Dry matter content of feces samples indicated that feeding this large amount of dried whey caused some diarrhea.

Library of Congress Subject Headings

Dairy cattle
Dairy cattle -- Feeding and feeds


Includes bibliographical references (pages 38-42)



Number of Pages



South Dakota State University


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Dairy Science Commons