Graduate Thesis Or Dissertation
 

Seasonal cattle and sheep diets on Festuca arundinacea-Trifolium subterraneum and Lolium perenne-Trifolium subterraneum pastures in western Oregon

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/1n79h7655

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  • Sheep and cattle dietary preferences were determined on tall fescue-subclover ( Festuca arundinacea-Trifolium subterraneum) and perennial ryegrass-subclover (Lolium perenne-Trifoliuni subterraneum) pastures in western Oregon during the spring and summer periods of 1964 and 1965. Esophageal-fistulated Willamette ewes and Hereford and Hereford-Angus yearling cattle were grazed separately on each pasture mixture at a low stocking rate in 1964 and both low and high stocking rates in 1965. Contrasting weather patterns in 1964 and 1965 provided conditions for high subclover production in the first year but virtually none the second year. Hence, dietary preferences were studied on favorable pasture composition in 1964 and under abnormal conditions in 1965. Under light grazing and high percentage subclover in 1964, the following results were obtained: (1) On both pasture mixtures, sheep selected diets containing more subclover than grass during spring and early summer. During mid to late summer, sheep preferred green tall fescue to dry subclover on Festuca pasture, but on the dry, perennial ryegrass pasture, dietary percentage of dry subclover increased. (2) Cattle preferred both grasses to subclover, with greater preference during summer. (3) Both sheep and cattle diets contained more crude protein than the forage available, with one exception. Cattle on ryegrass-subclover during summer selected only ryegrass which contained less crude protein than dry subclover. (4) Sheep dietary crude protein levels exceeded those of cattle at all times. Accordingly, sheep dietary crude protein content was nutritionally adequate by accepted feeding standards but cattle diets were deficient on ryegrass-subclover and borderline on tall fescue-subclover during August. (5) Estimated digestibility of forage, expressed as percent dry matter disappearance (PDMD) in vitro, was similar for both pasture mixtures, decreasing from approximately 65 in late April to approximately 45 in late August. In 1965 with two intensities of grazing and negligible amounts of subclover, results were as follows: (1) Effects of the two grazing intensities were more pronounced on forage than on dietary characteristics. Heavy grazing resulted in less forage available which contained more crude protein and more ash but was not different in PDMD from lightly-grazed forage. In contrast, dietary PDMD was greater under light than heavy grazing although dietary ash content increased. Dietary crude protein levels were unaffected by grazing intensity. (2) Sheep dietary preferences were altered in the absense of sub-clover; cattle preferences remained unchanged. Annual grasses were abundant in 1965, up to 70 percent of the forage in ryegrass pastures. Sheep preferred subclover although it occurred in amounts less than 6 percent of the total forage. In its absence, annual grasses were preferred to tall fescue and ryegrass during spring and early summer. Annual grass dry matter content increased more rapidly in June than tall fescue or ryegrass; sheep preferences switched to the perennial grass species at this time. Cattle, as in 1964, selected tall fescue and ryegrass in preference to annual grasses except for one period in May. (3) Both sheep and cattle diets contained more crude protein and ash than did the available forage. Dietary PDMD was not greater than forage PDMD until late season. (4) Sheep diets contained more crude protein and ash than did cattle diets. Also, sheep dietary PDMD exceeded that of cattle. Dietary crude protein and ash values from tall fescue forage exceeded those from ryegrass forage. The pattern and probable amount of salivary contamination of esophageal fistula samples varied between cattle and sheep and between the two pasture mixtures. Dietary crude protein deficiencies occurred by late July 1965, one month earlier than 1964. Cattle dietary protein levels were higher from tall fescue than from ryegrass forage but no differences existed between sheep dietary crude protein levels on either pasture mixture. Dietary PDMD was greatest on ryegrass. Dietary PDMD values did not exceed those of forage until mid-June and thereafter remained slightly below 50. Correlation coefficients among and between forage and dietary characteristics served to clarify existing relationships.
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file details BedellThomasE1966.pdf 2017-08-16 Público Baixar