Date of Graduation
Davis College of Agriculture, Natural Resources and Design
Animal and Nutritional Sciences
Edward C. Prigge.
To establish the effect of sward height, concentrate feeding time and grazing time management on performance of grazing cattle, thirty-two cross-bred beef (24 Angus and 8 Hereford) cows (632 kg BW) and calves (104 kg BW) were grouped by weight and calving date. They were randomly assigned to two sward height (SH) treatments (4 to 8 or 8 to 12 cm), replicated four times. The cows were fed a concentrate supplement (4.1 kg DM·cow -1·d-1) in the AM at 0700 h or PM at 1800 h (T), and either restricted to 12 h/d grazing (0700 to 1900 h) or unrestricted to 24 h/d grazing (MGT). The experiment was repeated over three 15-d periods in May, June/July and August 2000. The herbage on high SH pasture was higher (P < .05) in fiber and lower (P < .01) in crude protein compared to low SH herbage. For cows on restricted grazing, supplementing in the AM as opposed to PM resulted in greater (P < .05) forage DMI (8.6 vs. 8.1 kg/d) while unrestricted cows had greater forage DMI (8.4 vs. 8.2 kg/d) when supplemented in the PM as opposed to AM. Supplementing in the PM as opposed to AM resulted in greater (P < .05) herbage DMD (67.7 vs. 65.4%) for cows on high SH; cows on low SH had greater herbage DMD (66.3 vs. 64.5%) when supplemented in the AM. An interaction between T and MGT (P < .10) for digestible DMI (DDMI) was apparent. For cows restricted to 12 h/d grazing, supplementing in the AM as opposed to PM resulted in greater DDMI (5.0 vs. 4.7 kg/d) while unrestricted cows had greater DDMI (4.9 vs. 4.6 kg/d) when supplemented in the PM as opposed to AM. Supplementing in the PM as opposed to AM, increased the time spent grazing (P < .10) to a greater extent for restricted compared to unrestricted cows. When forage availability or grazing time is limiting, supplementing in the AM may result in greater forage utilization because of increased forage DMD and DDMI.
Gekara, Ondieki James, "Influence of sward height, daily timing of concentrate supplementation and grazing time management on pasture utilization of lactating beef cows" (2003). Graduate Theses, Dissertations, and Problem Reports. 1950.