Doctoral Dissertations

Seyoum Gelaye

Date of Award

8-1981

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Animal Science

Major Professor

Karl M. Barth

Committee Members

J.B. McLaren, J.R. Savage, E.W. Swanson

Abstract

A total of 59 beef cattle were used in investigations relating inherent and production differences to intake and digestibility of nutrients. Twelve lactating cows in a total-collection digestion trial, 24 cows in 3 successive acid-insoluble ash indicator-ratio digestion trials (trials 1, 2 and 3) and 23 yearling steers in another indicator-ratio digestion trial were fed mainly grass hay, grass silage and corn silage, respectively. The data were analyzed by the method of linear multiple regression.

The cows in the total-collection digestion trial offered the orchard-grass timothy hay (OGTH) consumed 1.6 kg more (P<.10) dry matter than those cows fed the tall-fescue-timothy hay (TFTH). More neutral detergent fiber (14.6%, P<.001), acid detergent fiber (14.7%, P<.01), hemicellulose (9.4%, P<.01), cellulose (21.7%, P<.001) and crude protein (12.5%, P<.01) were digested by the cows fed TFTH than those cows fed the OGTH. Cow weight was positively related to the digestibility of dry matter, neutral detergent fiber, neutral detergent solubles, acid detergent fiber and crude protein and the respective regression coefficients were .07% (P<.05), .06% (P<.10), .10% (P<.05), .04% and .10% (P<.10). Calf age accounted for about 29% (P<.05) of the variation in digestibility of the dry matter and for about 5% (P<.05) of the variation in digestibility of the neutral detergent fiber by their dams.

In the 3 successive indicator-ratio digestion trials the daily dry matter intake was higher in the pregnant than in the nonpregnant cows by about 2.0 kg (P .05) in a 66-day (range, 25 to 89 days) pregnancy (trial 2) and by about 1.5 kg (P<.01) in a 108-day (range, 67 to 131 days) pregnancy (trial 3). Stage of gestation did not affect nutrient intake at 34 days (range, 25 to 48 days) postconception (trial 1). However, as pregnancy advanced to 66 (trial 2) and 108 days (trial 3) a 1-day increase in the length of gestation was associated with a 40-g decrease in daily dry matter intake in trial 2 and a 30-g decrease in trial 3. The nonpregnant cows digested 3.9% more (P<.05) of the neutral detergent fiber and 4.3% more (P<.01) of the hemicellulose in trial 2 but .73% less (P<.05) of the hemicellulose in trial 3. In trial 2 a 1-day increase in the age of the in situ developing fetus caused a rise in digestibility of neutral detergent fiber and hemicellulose of .12% (P<.10) and .19% (P<.01), respectively. However, in trial 3, a 1-day increase in the age of the in situ developing fetus caused a reduction of .19% (P<.05) in the digestibility of hemicellulose. In trial 1, the cow whose milk production was higher by 1 kg digested significantly more of the dry matter (3.0%, P<.05), neutral detergent fiber (3.3%, P<.05), acid detergent fiber (3.6%, P<.05), hemicellulose (3.5%, P<.001) and cellulose (3.0%, P<.05).

The study with the yearling steers revealed that the steer with a 1-kg greater metabolic size consumed about 110 g more dry matter (P<.001) than the lighter steer. A comparison in nutrient digestibility among Angus (A), Hereford (H), A x H and H x A steers revealed that nutrient digestibility was similar in A, H and H x A. However, the A x H steer as compared to the A steers digested significantly less (P<.05) of the dry matter (7.8%), neutral detergent fiber (10.8%), neutral detergent solubles (6.4%), acid detergent fiber (10.3%), hemicellulose (12.0%) and cellulose (8.6%).

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Share

COinS