In Vitro Dry Matter Disappearance Research Articles

Relationship Between Tannin Levels and Nutritive Value of Sericea1

One low‐tannin sericea synthetic strain (Lespedeza cuneata (Dumont) G. Don) was compared with high‐tannin strains over different years, harvests, and test locations for in vitro dry matter disappearance (IVDMD). Concentrations of fiber and lignin were determined for representative samples of both low‐tannin and high‐tannin strains. Increments of a water‐soluble purified tannin fraction, “sericin,” were added to samples of one lowtannin and one high‐tannin strain for IVDMD analysis. The low‐tannin strain was consistently about 25% higher in IVDMD than high‐tannin sericea over years, harvests, and locations where mean values varied widely. There were only small differences among high‐tannin strains for IVDMD. The low‐tannin strain was quite similar to two high‐tannin strains in fiber and lignin concentrations. The results strongly support the conclusion that tannin was the cause of IVDMD difference between lowand high‐tannin genotypes. IVDMD of both low‐ and high‐tannin sericea decreased progressively with added increments of sericin. Both tannin and sericin were effective in limiting the IVDMD of sericea forage.

Nutritional Characteristics of Forage Sorghum and Sudangrass after Frost1

AbstractWater soluble carbohydrate (WSC) levels and in vitro dry matter disappearance (IVDMD) were evaluated in relation to changes in crude fiber levels of the forage.Mature forage sorghum (157 days of age), sampled three times after frost, averaged 25.3% WSC, 20% crude fiber, and 52.9% IVDMD. Sudangrass harvested under the same conditions averaged 3.1% WSC, 39.6% crude fiber, and 36.9% IVDMD. Third regrowth forage sorghum (56 days of age) analyzed 5.5% WSC, 23.8% crude fiber, and 57.1% IVDMD. The respective values of sudangrass of the same age were 3.4, 25.5, and 50.6%.The data obtained suggest that the nutritive value of some sorghums, as measured by IVDMD, does not decrease appreciably with increased maturity. The increase in percentage WCS observed in mature forage sorghum compared to less mature tissue was attributed to an increased stem diameter and an active pith parenchyma.

The relation of lignin, cellulose, protein, starch and ether extract to the ‘curing’ of range grasses

A field experiment was conducted over 2 years to evaluate five cultivars and four experimental synthetics of smooth bromegrass (Bromus inermis Leyss.), six cultivars of orchardgrass (Dactylis glomerata L.), four cultivars of timothy (Phleum pratense L.), three cultivars of tall fescue (Festuca arundinacea Schreb.) and two cultivars of reed canarygrass (Phalaris arundinacea L.). Herbage was sampled on seven dates during spring and early summer. Each treatment was replicated three times. Cultivars differed in nitrogen (N) concentration for orchardgrass, timothy and tall fescue. Timothy cultivars varied most in N, ranging from 24.7 g kg−7 for ‘Clair’ to 27.2 g kg−1 for ‘Verdant’. Within each species, the later maturing cultivars were generally highest in N. Cultivar differences in in vitro dry matter disappearance (IVDMD) were found for smooth bromegrass (range 41 g kg−1), orchardgrass (range 22 g kg−1) and timothy (range 27 g kg−1), but not for the other species. Cultivar effects for neutral detergent fiber were significant only for smooth bromegrass (range 27 g kg−1) which also differed in acid detergent fiber and hemicellulose. Cultivars of reed canarygrass, orchardgrass and timothy differed in cellulose, hemicellulose and acid-insoluble ash, respectively. Cultivar × date interactions were generally not significant except in 1982 when all species but orchardgrass had interaction effects for one or more constituents. These data indicate that grass cultivars differ in quality but that, within a species, cultivars generally respond similarly to advancing maturity.