Characterization of season and sampling method effects on measurement of forage quality in fescue-based pastures1

Abstract

Information on seasonal changes and effects of sampling methods on the measurement of forage quality is limited for fescue-based pastures. Eight continuously grazed, 0.76-ha, fescue-based pastures were used to compare forage type, method of collection, and seasonal effects on forage quality in a repeated-measures, split-plot design. Four pastures were interseeded with red clover in March 2000. Masticate (M; from four ruminally cannulated steers) and hand--clipped (C) samples were collected every 28 d from April to October 2000. Interseeding red clover did not affect (P > 0.10) OM, CP, NDF, and ADF concentrations or CP degradability. Sampling method and season interacted (P < 0.03) for OM, CP, NDF, and ADF concentrations. Concentrations of OM averaged 5 percentage units more (P < 0.01) in C than in M in all months and were more variable with M than with C. Samples clipped between April and September averaged 5.5 percentage units greater NDF (P < 0.01), 3.0 percentage units greater ADF (P < 0.01), and 4.5 percentage units less CP (P < 0.01) than masticate samples obtained during the same time period. Fiber and CP concentrations did not differ (P > 0.10) between C and M samples obtained in October. Differences in CP degradability estimates (using Streptomyces griseus protease) between the two sample types were greater in late-season samples than in samples obtained from April to June. When S. griseus protein degradability estimates were compared with in situ estimates for masticate samples, no differences (P > 0.10) were detected early in the season (April to June). However, the S. griseus procedure overestimated in situ values (P < 0.01) by an average of 3 percentage units in samples obtained between July and October. Differences in composition of C and M samples were substantial until late season, when opportunities for selective grazing were minimal. Small differences between S. griseus and in situ estimates of CP degradability indicate that the S. griseus procedure can yield useful CP degradability estimates for fescue-based pasture samples. Although it might be possible to apply correction values to clipped samples to estimate CP and fiber concentrations of diets selected by grazing cattle, inconsistent relationships preclude this approach for estimates of CP degradability.

Influence of soybean hull supplementation on rumen fermentation and digestibility in steers consuming freshly clipped, endophyte-infected tall fescue1

“…The forage maintained a similar quality throughout the experiment, except that the N concentration of the forage in period 2 declined by 0.5%. The initial forage quality and changes over time are similar to clipped samples that were taken by Dubbs et al (2003) to characterize tall fescue forage quality. In period 1, the nutrient content (NDF and N) was similar for the forage feed and orts (data not shown).…”

A longitudinal study of back dimension changes over 1 year in sports horses

“…The carbohydrate contents of grasses and legumes fluctuate seasonally (Burns and Chamblee, 2000;Dubbs et al, 2003), with the highest content in late spring, lowest in the summer and winter, and intermediate in autumn (Vervuert et al, 2005). We observed peak changes in back dimensions in late spring and negative changes in January, probably reflecting the seasonal fluctuations in nutritional value of the pasture.…”

Nutritive value of red clover and lucerne forages for ruminants estimated by in vitro and in vivo digestibility methods

“…Forage quality is affected by a combination of numerous factors such as stage of maturity of forage, forage species, environmental conditions (locality of growth, temperatures, and precipitations), and agronomic treatments including storage conditions (Dubbs et al, 2003;Pozdíšek and Vaculová, 2008;Tyrolová and Výborná, 2008;Jančík et al, 2009). Low-quality forage often does not provide enough energy to adequately maintain cows during lactation (Baumann et al, 2004).…”

“…Low-quality forage often does not provide enough energy to adequately maintain cows during lactation (Baumann et al, 2004). Several authors (Buxton, 1996;Van Soest, 1996;Dubbs et al, 2003;Jančík et al, 2010 and others) mentioned temperature, light intensity, water availability, altitude, seasonal changes, weather, and the maturity stage of plants as factors influencing forage quality. Some authors (Hunt et al, 1989;Bal et al, 1997) have investigated the time of harvest for assessing the optimal maturity stage of the plant concerning nutrient content and digestibility.…”