Steer Gains under Six Systems of Coastal Bermudagrass Utilization

Hart, Richard H.; Marchant, W. H.; Butler, J. L.; Hellwig, R. E.; McCormick, W. C.; Southwell, B. L.; Burton, Glenn W.

doi:10.2307/3897142

Cited by 22 publications

(9 citation statements)

References 8 publications

(6 reference statements)

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“…These workers also noted low forage availability at the end of a rotation grazing period depresses gains and reduces total forage production. Hart et al (1976) found the average daily gain of steers was strongly and negatively correlated with grazing pressure, being lightest under continuous grazing and heavier under rotation and strip grazing.…”

Section: Grazing Systemsmentioning

confidence: 91%

Factors Affecting Forage Intake by Range Ruminants: A Review

Allison¹

1985

Journal of Range Management

161

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Variation in voluntary forage intake is undoubtedly the major dietary factor determining level and efficiency of ruminant production. This variation is largest and least predictable for grazing ruminants. Range ruminant productivity and efficiency is relatively low due, in part, to intake limitations; therefore, productivity could probably be increased most by increasing intake. Most available literature points to digestibility and rate of ingesta passage and reticula-rumen fill as primary mechanisms of intake regulation in range ruminants. Body size and physiological status of ruminants appear to have the largest effect of animal-related factors in governing level of voluntary intake. Kind and amount of supplementation, forage availability, and grazing intensity are major management-controlled variables affecting intake by domestic range ruminants.

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Section: Grazing Systemsmentioning

confidence: 91%

Factors Affecting Forage Intake by Range Ruminants: A Review

Allison¹

1985

Journal of Range Management

161

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“…Grazing pressure index is defined as heifer-days Mg-' (1,000 kg) of forage production at peak standing crop. Hart (1972) originally used the term "grazing pressure" to describe this ratio of animal-days to forage production, and grazing pressure was subsequently used in this way by McCartor and Rouquette (1977), Hart et al (1976, 1983, 1988a, 1988b), Guerrero et al (1984, and others. However, Scarnecchia (198.5) re-defined grazing pressure as "animal demand per unit weight of forage at any instant" and defined grazing pressure index as "ratio of animal demand to forage over a period of time.…”

Section: Heifer Gainsmentioning

confidence: 99%

Grazing Intensities, Vegetation, and Heifer Gains: 55 Years on Shortgrass

Hart¹,

Ashby²

1998

Journal of Range Management

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Shortgrass rangeland, dominated by blue grama (Bouteloua gracilis [H.B.K.] Lag. ex Steud), was grazed at 3 intensities, equivalent to mean stocking rates of 16.7, 23.0, and 36.5 beiferdays ha-', from 1939 through 1994. Few changes in plant communities had been documented by the early 1970's. In 1992-1994, frequency of occurrence, basal and foliar cover, and biomass at peak standing crop (PSC) were determined on the remaining pasture at each grazing intensity, and on 3 ungrazed exclosures. Blue grama and buffalograss (Buchloif dactyloides [Nutt.] Engelm.) increased, and western wheatgrass (Puwopyrum smithii [Rydb.] A. Love) and needle-and-thread (Spa coma&z Trin. & Rupr.) decreased, as grazing intensity increased. Redthree-awn (Aristiah longisetu Steud.) was most plentiful under light grazing. Basal cover and biomass of forbs were lower under grazing than in exclosures, but differences in biomass were not significant. Shrubs and half-shrubs decreased as grazing intensity increased. Frequency and cover of plains pricklypear (Opuntia polyacantha Haw.) were higher in the exclosures and under fight grazing than under moderate or heavy grazing; biomass was 4 to 6 times as high in the exclosures as under any grazing intensity, Heifer gains declined linearly with increasing grazing pressure index. Optimum (most profitable) stocking rate was about 20% higher than that under the moderate grazing intensity, under which biomass production was maintained and shrub and pricklypear remained at low levels. Returns to land, labor, and management were only slightly higher under the optimum stocking rate than under the moderate grazing intensity. The moderate grazing intensity appears to be both profitable and sustainable.

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“…2 it is observed that M at the value of convergence criterion defined is 83 g of medium digestibility forage kg-1 of body weight day-1 • Obviously, a steer could not possibly consume that amount of dry matter as green forage. Hart et al (8) reported average daily dry matter intake of harvested Coastal bermudagrass of21 to 28 g kg-' ofbody weight day-1 for steers weighing 245 to 260 kg at the beginning of the season. Therefore, the 83 g kg-1 body weight of forage dry matter indicates the amount of forage below which the lack of selectivity starts to limit steer performance.…”

Section: The Differential Equationmentioning

confidence: 99%

“…A number of authors have related the performance of grazing ruminants to the amount of available forage. Hart et al (8) reported that average daily gain (ADG) was strongly and negatively correlated with grazing pressure (r 2 = 0.60). Jamieson and Hodgson (10) reported a decline in intake of approximately 18% as daily herbage allowance was reduced from 90 to 30 g of forage dry matter per kg liveweight.…”

mentioning

confidence: 99%

Prediction of Animal Performance on Bermudagrass Pasture from Available Forage¹

Guerrero¹,

Conrad²,

Holt³

et al. 1984

Agronomy Journal

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Bermudagrass [Cynodon dactylon (L.) Pers.] is a major warmseason perennial grass grown on improved pastures in the South. Available forage and its digestibility vary widely in a normal grazing season on bermudagrass pasture. A method is needed to predict steer (Bos sp.) gains from the amount and digestibility of available forage. Five bermudagrass cultivars differing in digestibility were grazed at different grazing pressures to produce four levels of available forage. Forage was classified by concentration of in vitro digestible dry matter (IVDDM) as high (>600 g kg−1 IVDDM), medium (530 to 600 g kg−1 IVDDM), or low ( <530 g kg−1 IVDDM) digestibility. At each level of IVDDM, average daily gain (ADG) of steers was fitted to an asymptotic function of available forage. On high, medium, and low digestibility forages, approximate asymptotic ADG values were 0.94, 0.74, and 0.31 kg, and 68,83, and 89 g forage kg−1 body weight day−1, respectively, were needed to produce the asymptotic ADG values. For steers to maintain their weight on high, medium, and low digestibility forage, 14,18, and 43 g forage dry matter kg−1 body weight day−1, respectively, must be present. Because the quantities of available forage required for maximum steer gains or even for maintenance were far in excess of what the steers could physically consume, it appears that opportunity for selective grazing is necessary.

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Steer Gains under Six Systems of Coastal Bermudagrass Utilization

Cited by 22 publications

References 8 publications

Factors Affecting Forage Intake by Range Ruminants: A Review

Factors Affecting Forage Intake by Range Ruminants: A Review

Grazing Intensities, Vegetation, and Heifer Gains: 55 Years on Shortgrass

Prediction of Animal Performance on Bermudagrass Pasture from Available Forage¹

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Steer Gains under Six Systems of Coastal Bermudagrass Utilization

Cited by 22 publications

References 8 publications

Factors Affecting Forage Intake by Range Ruminants: A Review

Factors Affecting Forage Intake by Range Ruminants: A Review

Grazing Intensities, Vegetation, and Heifer Gains: 55 Years on Shortgrass

Prediction of Animal Performance on Bermudagrass Pasture from Available Forage1

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Prediction of Animal Performance on Bermudagrass Pasture from Available Forage¹