Masters Theses

Date of Award

6-1973

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Husbandry

Major Professor

Karl M. Barth

Committee Members

Robert S. Dotson, James B. McLaren

Abstract

A three-year grazing trial was conducted to evaluate the production of slaughter heifers using fescue-lespedeza (F-L) and orchardgrass-clover (O-C) pastures and two levels of winter feeding.

Eight three-acre pastures were used: four O-C pastures that were reseeded in 1961 and four F-L pastures that were established in 1954 and renovated by light disking and overseeding with lespedeza in 1962. The soils on which pastures were established were all Land Capability Class III. Pastures were fertilized with P, K, and Ca according to soil test recommendations; no nitrogen fertilizers were used. Pastures were clipped to remove excess growth and to keep forage in a growing stage.

Heifers selected for the grazing trial came from Tennessee Feeder Calf Sales and were of similar weight (approximately 525 pounds), type grade and condition grade. Before heifers were placed on trial, they were implanted with 24 mg of diethylstilbestrol. Heifers were assigned to one of the eight experimental groups according to body weight and condition grade. Results of the study were analyzed using an analysis of variance.

During the fall pasture phase, which averaged 42 days, F-L grazed heifers gained 0.23 pounds per day while O-C grazed heifers lost 0.24 pounds per day (significant, P<.05). Heifers were removed from all pastures at the same time; therefore, winter productive potential of F-L pastures were not accurately evaluated because they were still growing after O-C pastures were depleted of forage.

During the winter silage feeding phase, which averaged 99 days, heifers fed the high-level winter ration gained 1.25 pounds per day while those fed the low-level winter ration gained 0.75 pounds per day. Heifers fed the high-level winter ration had a lower feed conversion than those fed the low-level winter ration. Heifers that received the high-level ration also had higher condition scores than those that received the low-level winter ration.

During the spring and summer grazing phase, which averaged 111 days, heifers that grazed O-C pastures outgained those that grazed F-L pastures (1.24 vs. 0.85 pounds per day, respectively). The heifers grazing F-L pastures that had received the low-level winter ration outgained the high-level winter ration heifers 1.04 to 0.65 pounds per day, respectively. O-C pastured heifers that had received the low-level winter ration outgained high-level winter ration heifers 1.40 to 1.07 pounds per day. By the end of the spring and summer pasture phase, heifers that had been on the low wintering level had compensated for the lower gains and decreased condition made during the winter.

Heifers that grazed O-C pastures averaged 0.6 condition grade units higher than those grazing F-L pastures during the spring and summer grazing phase.

During the full-feed phase (average 53 days), heifers that had grazed F-L pastures made higher gains than those that had grazed O-C pastures. The F-L heifers that had been fed the high winter ration, however, did not gain as well as the O-C pastured heifers that had been fed the low-level winter ration. In comparing the wintering level effects on the full-feed phase, the F-L heifers on low-level winter ration outgained the F-L heifers on high-level winter ration 2.10 to 1.81 pounds per day, respectively. O-C heifers that were fed the low-level winter ration outgained those fed the high-level ration 1.85 to 1.67 pounds per day, respectively. Heifers that grazed F-L pastures increased 0.75 condition grade units while heifers that had grazed O-C pastures increased 0.25 condition grade units. Those heifers on the low winter level gained 1.0 condition grade units while those that were wintered on the high-level gained 0.7 condition grade units.

Overall daily gains for heifers were 1.02, 0.97, 1.01, and 0.99 pounds per day for F-L low-level ration, F-L high-level ration, O-C low-level ration and O-C high-level ration, respectively. Both O-C and F-L pastures and both levels of winter feeding produced similar overall average daily gains. Condition grades of heifers at the beginning of each year of the study averaged Low Good (9.1). Average USDA slaughter grades of individual carcasses were Average Good (10.5). Final weights and final USDA slaughter grades did not differ significantly (P<.05). In 1968, carcass data were very similar.

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