Studies on the diet of the grazing animal. I. Seasonal changes in the diet of sheep grazing on pastures of different availability and composition

Abstract

The diet of grazing sheep was studied by using animals with oesophageal fistulas. Seasonal changes in the botanical and chemical composition of the diet when grazing Phalaris–annual grasses–subterranean clover pasture are described. The effect of grazing intensity on diet is considered. A comparison was made of diets on seven pasture species. None of the species examined had a useful qualitative superiority over Phalaris either in winter or in summer, when the digestibility of this species declines considerably. Relations between botanical and chemical composition of the diet and the pasture are discussed. Significant relations were established between the nitrogen and soluble carbohydrate contents of diets and their digestibility.

Nutritive Content of Sheep, Goat, and White-Tailed Deer Diets on Excellent Condition Rangeland in Texas

“…Rangeland in low condition classes may require more protein supplement for longer periods due to the reduced diversity of high-quality plants and inadequate forage quantity. also reported that CP content of sheep diets was not limiting to animal production (Arnold et al 1966;Bedell 1971;Wilson 1976).…”

Not all sheep prefer clover: diet selection revisited

“…clover) in the diet against . its proportion in the sward (Meyer et al 1957;Weir &Torell 1959;Arnold 1960Arnold , 1987Wilson 1963;Van Dyne & Heady 1965;Arnold et al 1966;Grimes et al 1966;Bedel 1968Bedel , 1973Hamilton et al 1973;Leigh & Holgate 1978;Briseno & Wilman 1981;Milne et al 1982;Clark & Harris 1985;Curll et al 1985). A major problem with this approach, particularly if the real aim is to measure preference, lies in estimating the proportion of that item that is available to the sheep.…”

“…Some data from continuously grazed swards suggest that grass and clover are distributed in a similar manner from the top of the sward (Johnson et al 1989). Also, Arnold et al (1966) tested diet selection under continuous grazing throughout 2 years of study and found essentially no difference between the proportion of clover in the diet and that in the sward (see also Grimes et al 1966;Arnold 1987; but see Bedell 1968). Furthermore, Milne et a/.…”

“…This belief persists (e.g. Vallentine 1990) despite an equally large body of evidence suggesting a lack of selectivity in sheep (Arnold et al 1966;Grimes et al 1966;Clark et al 1982;L'Huillier et al 1984L'Huillier et al , 1986Arnold 1987). Vallentine (1990), in a new textbook on grazing management, goes so far as to state that the selectivity index (percentage clover in the diet divided by the percentage clover in the sward) of sheep grazing clover is 1-8 (taken from the results of Van Dyne & Heady 1965; see also Ridout & Robson 1991, for more on constant preferences).…”

Cattle Selection for Aspen and Meadow Vegetation: Implications for Restoration

“…The major increase in lignin content occurs when plants change from the elongation stage to the reproductive stage (Chen et al 2002). Vegetation containing high ADF values have lower digestible energy concentration and can restrict dry matter intake, ultimately decreasing the amount of energy cattle receive (Arnold et al 1966;Moore and Jung 2001). Therefore, aspen suckers, with ADF levels never exceeding 28% provided a higher quality diet that meets energy demands of cattle.…”