Forage Quality Index Research Articles

Fibre Analyses of an Evergreen, a Deciduous Woody and a Non-woody Dicotyledon: Comparison of Two Techniques

Forage fibre content is frequently used as an index of forage quality, where high fibre content indicates low forage quality. Although the acid-detergent fibre (ADF) and acid-pepsin digestibility (AP) techniques have provided similar estimates of forage quality for a variety of herbaceous monocotyledonous plants, these techniques have provided dissimilar estimates of fibre content for a willow, a deciduous woody dicotyledonous forage. This lack of correlation has been attributed to variations in the proportions of stem and leaf material that comprised the willow samples. Both the ADF and AP techniques were used to compare the estimates of the fibre content of willow leaves, willow sterns, an evergreen ericaceous dwarf shrub. and a non-woody dicot. A strong negative correlation and a linear relationship were found between the fibre content, as determined by ADF, and the digestibility, as determined by AP, for each sample type. The linear relationships were significantly different for all sample types. This suggests that, although phenological changes in fibre content may differ between samples, the two techniques provide a very similar estimate of forage quality in dicotyledonous forages. In the case of deciduous woody dicotyledons, leaf and stem material must be separated prior to the analyses.

Potential for woody plant control by Spanish goats in the sagebrush steppe

Botanical composition of the diet of eight Spanish goats was studied on the Northern Great Basin Experimental Range during two stages of plant phenology (active growth in early July and cured forage in mid-August) to assess their potential for the control of sagebrush ( Artemisia tridentata sspp. wyomingensis Nutt.) and western juniper ( Juniperus occidentalis Hook.) and their nutritional status on sagebrush-steppe rangelands. Diets were quantified by documenting the number of visits to each species, the bites harvested and time expended grazing each forage over 4 consecutive days in each period. Forage chemical characteristics evaluated included: CP, NDF, ADF, ADL and IVDMD. Diet composition and forage quality indices varied significantly ( P < 0.05) with changes in plant phenology. Vegetation cover averaged 52% in the pasture and consisted of 36% grasses, 8% forbs, 7% shrubs and 0.6% trees. Available herbage (excluding woody plants) was 534 kg ha −1 during active growth trials and 572 kg ha −1 when forages had cured. When forages were green goats acquired 28% of their total bites from grasses, 71% from forbs, 0.3% from shrubs and 0.9% from juniper trees. After forages had cured values were 35% from grasses, 56% from forbs, 0.1% from shrubs and 8.8% from juniper. The browsing of juniper (both foliage and bark), after herbaceous forages had cured, was the only substantive use of woody plants. Sagebrush was only lightly used (0.2% of total bites) when herbaceous forages were actively growing. Available herbage was of relatively high quality during both trials. When forages were actively growing, CP of grasses ranged from 8.9 to 5.6%, forbs from 17.7 to 8.5%, sagebrush scored at 8.5%, juniper foliage at 8.1% and juniper bark at 3.2%. After herbaceous forages had cured, grass CPs ranged between 6.2 and 3.1%, forbs from 10.4 to 4.4%, shrubs were not sampled and juniper foliage averaged 7.6%. Given the low levels of browsing exhibited by goats on sagebrush and juniper we see little opportunity for control of these woody plants when pastures provide a diverse ( N = 25 species) array of readily available (534–572 kg ha −1) and nutritious forages and pastures are lightly stocked (0.63 goats ha −1 month −1). We do need, however, to further explore their potential for control of these species under several other regimes. These include extended trials on more deteriorated rangelands, trials during seasons or conditions where forage is limited and the animal's selective opportunity is restricted and trials in high quality environments on newly established sagebrush and juniper seedlings.

Potential for woody plant control by Spanish goats in the sagebrush steppe

The botanical composition of the diet of eight Spanish goats was studied on the Northern Great Basin Experimental Range during two stages of plant phenology (active growth in early July and cured forage in mid-August) to assess their potential for control of sagebrush ( Artemisia tridentata subspp. wyomingensis Nutt.) and western juniper ( Juniperus occidentalis Hook.) and the nutritional value of their diets on sagebrush steppe rangelands. Diets were quantified by documenting the number of visits to each species, the number of bites harvested and time expended grazing each forage over four consecutive days in each period. Forage chemical characteristics evaluated included: CP, NDF, ADF, ADL and IVDMD. Diet composition and forage quality indices varied significantly ( P < 0.05) with changes in plant phenology. Vegetation cover averaged 52% in the pasture and consisted of 36% grasses, 8% forbs, 7% shrubs and 0.6% trees. Available herbage (excluding woody plants) was 534 kg ha −1 during active growth trials and 572 kg ha −1 when forages had cured. When forages were green goats acquired 28% of their total bites from grasses, 71% from forbs, 0.3% from shrubs and 0.9% from juniper trees. After forages had cured values were 35% from grasses, 56% from forbs, 0.1% from shrubs and 8.8% from juniper. The browsing of juniper (both foliage and bark), after herbaceous forages had cured, was the only substantive use of woody plants. Sagebrush was only lightly used (0.2% of total bites) when herbaceous forages were actively growing. Available herbage was of relatively high quality during both trials. When forages were actively growing, CP of grasses ranged between 8.9-5.6%, forbs from 17.7-8.5%, sagebrush scored at 8.5%, juniper foliage at 8.1% and juniper bark at 3.2%. After herbaceous forages had cured, grass CPs ranged between 6.2 and 3.1%; forbs from 10.4 to 4.4%; shrubs were not sampled; and juniper foliage averaged 7.6%. Given the low levels of browsing exhibited by goats on sagebrush and juniper we see little opportunity for control of these woody plants when pastures provide a diverse ( n = 25 species) array of readily available (534–572 kg ha −1) and nutritious forages and pastures are lightly stocked (0.63 goats ha −1 month −1). We do need, however, to explore further their potential for control of these species under several other regimes. These include: extended trials on more deteriorated rangelands; trials during seasons or conditions where forage is limited and the animal' s selective opportunity is restricted; and trials in high quality environments on newly established sagebrush and juniper seedlings.

Classification of Erythrina provenances by rumen degradation characteristics of dry matter and nitrogen

Some species of the genus Erythrina have considerable potential as forage, but information on their nutritional value is scanty. The objective of the study was to define groups of Erythrina provenances based on rumen degradation parameters for dry matter and nitrogen which would be useful in the selection of provenances for detailed nutritional or tree improvement studies. Degradation parameters (i.e. soluble fraction (a), slowly degradable fraction (b), rate of degradation (c) and extent of degradation (a + b) were estimated for twenty Erythrina provenances belonging to seven species (E. abyssinica, E. bentipoeme, E. brucei, E. burana, E. melanacantha, E. poeppigiana and E. variegata)). The data were subjected to principal component and cluster analyses for grouping, and the 20 provenances were placed into four distinct cluster groups. Provenances of E. brucei and E. abyssinica belonged to three clusters, whereas provenances of E. burana and E. variegata were confined to one cluster. Using extent of dry matter and nitrogen degradation values of 71 and 86% respectively, as a forage quality index, members of clusters 1 and 2 (i.e. E. abyssinica, ILCA 10606; E. brucei, ILCA 10579, 10625, 10628, 10637, 10643; E. burana 10575, 10641, 12157; E. melanacantha ILCA 10574 and E. variegata ILCA 14991 and 14994), appeared to be superior in quality to their counterparts in clusters 3 and 4. The results suggested existence of intra and inter-species variation in rumen degradation characteristics for dry matter and nitrogen within the genus Erythrina.

Forage Quality and Harvest Index of Corn Hybrids under Different Growing Conditions

AbstractRecent studies suggest that grain content may not necessarily predict corn (Zea mays L.) forage quality. Field studies were conducted at two New York locations in 1991 and 1992 to evaluate forage quality differences among commercial corn hybrids across different growing conditions and the relationship between the harvest index (HI) value and forage quality. Twelve hybrids, which ranged in relative maturity from 95 to 116 d, were evaluated in two experiments according to maturity differences. Each hybrid was hand‐harvested at the 1/2‐milk‐line stage or 350 g kg−1 dry matter (DM) concentration to determine DM yield, HI, whole‐plant N, neutral‐detergent fiber (NDF), acid‐detergent fiber (ADF), lignin, and in vitro true digestibility (IVTD). Although the relationship among hybrids for NDF was consistent across three of four site‐year comparisons, year × hybrid and location × hybrid interactions existed in one experiment because some hybrids received a killing frost at one location before attaining the 1/2‐milk‐line stage. In contrast, hybrid interactions for IVTD did not exist, which suggests a consistent relationship among hybrids for digestibility, even if hybrids received a killing frost between the dent and 1/2‐milk‐line stage. The HI correlated closely with NDF (−084 and ‐0.82) and IVTD (0.79 and 0.63) in both experiments. Likewise, lignin correlated closely with NDF (0.84 and 0.88) and IVTD (−0.76 and −0.79). The data suggest that livestock producers can continue to choose hybrids with high grain content if relatively low fiber and high digestibility are of prime interest.

Forage Fibre Analyses: a Comparison of Two Techniques.

Forage fibre content is frequently used as index of forage quality where high fibre content indicates low forage quality. Fibre content is usually estimated by the familiar ADF technique. An alternative method, the acid-pepsin digestibility (AP) technique, provides an estimate of forage digestibility where low digestibility indicates a high fibre content. Fibre content estimates in herbaceous forage (Carex atherodes, C. aquatilis, Phalaris arundinacea, Calamagrostis spp., Agropyron trachycaulum [Elymus trachycaulus] and Hordeum jubatum) were compared by the ADF and AP techniques. There was a strong negative correlation between the fibre content, as determined by ADF, and the digestibility, as determined by AP, in a wide variety of herbaceous forages. This suggests that both techniques provide a very similar estimate of forage quality in herbaceous forages. Contrastingly, a similar analysis on Salix spp. and lichen showed a poor correlation between techniques, suggesting dissimilar estimates of fibre content of these forages.

The effect of simulated acid rain and ozone on the yield and quality of glasshouse-grown alfalfa

Under glasshouse conditions, alfalfa Medicago sativa L. cv ‘Saranac’ was exposed to simulated rain at pH values of 5·6 and 3·0, 1–2 times per week with or without ozone (ranging from 98 to 294 μg m −3 for 7 h/day) once a week. The pesticide diazinon (o,o-diethyl-o-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothiate), reported as having anti-oxidant activity on pinto bean, was used in the first of these experiments, but protection from ozone injury was not observed. After weekly exposures to simulated rain and ozone over a two-month period, no yield reductions occurred in a single alfalfa harvest. When rain treatments were increased to twice weekly over two consecutive harvests, no significant yield reductions attributable to increased acidity were found. Percent dry weight in all experiments was either increased or unaffected by simulated rain and ozone exposures. Percent nitrogen, an indicator of forage quality, showed decreases of 18–37% in plants treated with simulated rain at pH 3·0 when compared with control plants. The data revealed no synergistic-like effect on both the yield and quality of alfalfa due to simulated rain and ozone.

Nitrogen Effects on Crested Wheatgrass as Related to Forage Quality Indices of Grass Tetany1

AbstractNitrogen fertilization of forage is often accompanied by an increased incidence of grass tetany. A field experiment was established on two calcareous soils to evaluate the effects of N fertilizer on forage quality indices of grass tetany. Nitrogen, as NH4NO3, was applied at 0 and 150 kg N/ha in each of 2 years to separate plots. The crested wheatgrass [Agropyron desertorum (Fisch.) Schult] forage was harvested at regular intervals in the Spring tetany period during 1968 through 1971. Forage was analyzed for inorganic cations, N, total water‐soluble carbohydrates (TWSC), aconitic acid, higher fatty acids (HFA), dry matter, and ash alkalinity — a measure of total organic acids.Nitrogen fertilizer increased the concentrations (equiv. basis) of forage Mg and Ca more than the increase in K, thus slightly reducing the K/(Ca + Mg) values when compared to the unfertilized forage. However, forage K/(Ca + Mg) values were usually less than the 2.2 value above which the incidence of grass tetany increases rapidly. The potential dietary benefits from the higher Mg concentrations may have been offset by increased concentrations of K, N, HFA, N/TWSC, and aconitic acid, since these parameters are associated with decreased Mg availability to cattle.Low values for hypothetical blood serum Mg (calculated from forage N, Mg, and K concentrations) coincided with the occurrence of grass tetany in the field. The calculated serum Mg values were lower in the N‐fertilized forage than in the control.The aforementioned effects of N fertilization should not deter the judicious use of N for optimizing forage yields on semiarid ranges, since other research workers have found that grass tetany losses can be reduced by supplementing animals with Mg.