Effect of Continuous Grazing on the Diet of Steers

David A. Yates, D. C. Clanton, J. T. Nichols
1982 Journal of range management  
Continuous grazing of Sandhill native forage at a normal stocking rate in late August had no effect on organic matter intake (OMI), but the protein content and in vitro organic matter digestibility (IVOMD)5declined over a 3-week period. The average OMI was 75 g/kg W' . As the availability of forage declined, the ability of the steers to selectively graze was apparently reduced. Similarly, continuous grazing of mixed prairie-type range from October 30 to March 13 had no effect on OMI but the
more » ... ein content of the diet was reduced. The IVOMD did not change during the winter grazing trial. The average OMI was 66 g/kg W.75 Steer calves gained .24 kg daily during the grazing period. Crampton et al. ( 1960) stated, "Of all 6000 feeds thus far studied, forages continue to present the greatest problem of a meaningful quantitative description of their nutritive value."Nutritive value is the product of quantity and quality of the diet consumed by grazing animals. Crampton et al. (1960) also stated, "The importance of the relative intake of a forage as compared to its digestibility in determining the numerical value of the Nutritive Value Index is approximately 70 vs 3070, respectively." The best assessment of the qualitative value of the diet of a grazing animal is determined using forage samples collected by esophageal fistula (Lesperance et al. 1974, Kartchner and Campbell 1979) . The quantity of forage consumed by the grazing animal can be measured indirectly using indicators (Harris et al. 1967 , Raleigh et al. 1980 ) with or without total fecal collection (Kartchner and Campbell 1979). Many factors, i.e., weather, type of forage, chemical composition, and plant maturity, have been associated with the quantity and quality of the grazing animal's diet. An excellent review of these factors appears in the work of Kartchner and Campbell 1979. The effect of continuous grazing on voluntary forage intake and diet quality have not been studied extensively on native range, especially Sandhills or mixed-prairie type vegetation. The objective of the research reported here was to study the effect of continuous grazing on the quantity and quality of steer diets when grazing Sandhills range in late summer or mixed-prairie type range during the winter. Materials and Methods Two experimental pastures of different vegetation types, located in west central Nebraska, were used for two separate grazing trials. Both study areas were located within the 43 to 48-cm precipitation zone. Stocking rates were calculated for each study area in accordance with site potential and range condition class as suggested by Soil Conservation Service guidelines. Pastures were fully stocked Authors are former graduate assistant in animal science (now Extension specialist in animal science, Univ. of Wyoming), professor of animal science and professor of agronomy (range and forage), Univ. of Nebraska North Platte Station, North Platte.
doi:10.2307/3898313 fatcat:vmbdy55qfjcc7onwaxbzff45vy