Date of Award:

1982

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Animal, Dairy, and Veterinary Sciences

Advisor/Chair:

Melvin J. Anderson

Abstract

Twenty-four lactating cows were randomly assigned to three treatments within eight each 3 x 3 latin squares with three periods of 21 days duration. Three processing treatments of barley were 1) steam-rolled, 2) ground (fine), and 3) soak-rolled (soaked in water for appr. 24 hours, rolled, and fed within 48 hours). All rations were fed ad libitum and were comprised of 24% alfalfa hay, 16% corn silage, 35.5% barley, 12% whole cottonseed, 12% wheat bran, 0.3% salt, and 0.3% dicalcium phosphate on a dry matter (DM) basis. Electronic doors were used to collect individual feed intake data. Rations and feces grab samples were collected and analyzed chemically. Dry matter digestibility (DMB) was determined by acid insoluble ash. Body weights (BW) were taken every two weeks. Milk production was recorded daily and composition of milk fat, protein, and solids-not-fat (SNF) was determined twice a month. Production (kg/day) of milk, butterfat, protein, SNF; DM consumed (kg); percent DMD; efficiency 1 (kg) 4% fat corrected milk (FCM)/kg DM intake); and efficiency 2 (kg) 4% FCM/kg digestible dry matter (DDM) for rations 1, 2, and 3 were 24.2, 22,7, 21.8; 0.88, 0.80, 0.86; 0.83, 0.78, 0.74; 2.17, 2.04, 2.01; 19.8, 20.8, 18.7; 67.05, 71.05, 67.20; 1.16, 1.04, 1.18; 1.76, 1.46, and 1.83, respectively.

The method of processing barley caused significant differences (P<.01) in production of milk, percent fat, amount of protein, DDM, and efficiency 1 and 2. Likewise, it caused significant differences (P<.05) for 4% FCM, amount of fat, and SNF, and DM consumed, but there were no significant differences for SNF, proteing and percent DMD amount of feed consumed and refused, DM refused, and BW. Treatment by period interactions were significant (P<.01) for feed and DM consumed, feed efficiency 1 and 2, and DDM. Group by period interactions were highly significant (P<.05) for BW, (P<.05) for total milk production, and amount of protein. Correlations among all the variables were with those previously reported except for the correlations of percent SNF with total milk production, which was positive but non-significant (P>.05).

The cows fed ration 1 produced more total milk and protein than those on rations 2 and 3. There were not differences in feed consumed (or fed) among cows on the three rations. Cows on ration 2 consumed more DM than those on ration 3, but cows on ration 1 did not differ in DM consumption from those on either of the other treatments. Cows on ration 3 had the highest fat test, but showed no differences in the amount of fat produced compared to the cows on rations 1 and 2.

Cows on ration 2 had the highest percent DMD and DDM and since these were not the highest in total milk production but were the highest in DM consumption, they were the least feed efficient. Additionally, since cows on ration 3 consumed less DM than those on ration 2, the former had high feed efficiency equal to cows on ration 1.

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