Nutrient content of whole cottonseed

The objective of this study was to determine if the nutrient and gossypol contents and in vitro digestibility of 3 types of genetically modified whole cottonseed differed from traditional whole cottonseed. Samples of seed from traditional (no genetic modifications) and genetically modified varieties of cotton grown in 1999 and 2000 were analyzed. Genetic modifications included the insertion of genes to protect cotton from insect pests (Bt), and damage from glyphosate herbicides (RR), and from both (Bt/RR). Year effects were significant for in vitro dry matter (DM) digestibility, gossypol, DM, crude protein (CP), fat, neutral detergent fiber (NDF), acid detergent fiber (ADF), and ash. Higher rainfall resulted in higher CP, fat, and ash and lower NDF and gossypol. There were no differences among seed types for ground or whole seed digestibility, DM, CP, fat, NDF, ADF, ash, lignin, net energy for lactation, amino acids, total fatty acids, or seed index. Overall, the nutrient content and digestibility of varieties of genetically modified seed were similar to that of varieties of traditional whole cottonseed.     

The influence of cooking technique on dietary fibre of boiled potato

Samples of twenty-five different cultivars of potatoes were prepared and examined after cooking by boiling and by pressure cooking, peeled and 'in the jacket' in a factorial design to study the effect of cooking on dietary fibre fractions of potatoes. Raw samples were prepared as control.
The samples were analysed for acid detergent fibre (ADF) and lignin by published procedures. Filtration problems were encountered with the published procedure for neutral detergent fibre (NDF) giving rise to lack of reproducibility. Reproducibility was restored by introducing a short incubation of the sample with α-amylase enzyme ( Bacillus subtilis ) prior to the normal detergent digestion.
The lignin content of all samples was < 0.25% on a dry matter basis. Both ADF and NDF increased on cooking but boiled samples did not differ from pressure cooked samples. Cooking 'in the jacket' gave higher ADF values than peeled samples but the effect was not observed for NDF values.
Cultivar differences were significant for both ADF and NDF values but as the samples were all from a single season's crop in a single field a definitive ranking is not possible.     

Sodium sulphite effects on recovery and composition of detergent fibre and lignin from forage legumes varying in levels of proanthocyanidins

Alfalfa (Medicago sativa L), red clover (Trifolium pratense L), birdsfoot trefoil (Lotus corniculatus L), sainfoin (Onobrychis viciifolia Scop), crownvetch (Coronilla varia L), cicer milkvetch (Astragrlus cicer L), sericea lespedeza (Lespedeza cuneata (Dum-Cours) G Don) and kura clover (Trifolium ambiguum M Bieb) were subjected to sequential detergent fibre analysis to investigate the effects that the addition of sodium sulphite to neutral detergent has on the recovery and composition of fibre and lignin from forage legumes that vary in levels of proanthocyanidin (PA). Soluble, insoluble and neutral detergent insoluble PA (NDIPA) concentrations were highest in sericea, moderate in crownvetch, sainfoin and birdsfoot trefoil and absent in alfalfa, cicer milkvetch, red clover and kura clover. Addition of sodium sulphite reduced levels of neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL), neutral detergent insoluble nitrogen (NDIN) and acid detergent insoluble nitrogen (ADIN) recovered from most forages tested. The addition of sodium sulphite effectively eliminated NDIPA from NDF. The difference between fibre fractions prepared without and with the addition of sodium sulphite during the neutral detergent procedure was related to PA concentration. Neutral detergent fibre difference was positively correlated with soluble PA (r = 0.730, p = 0.0001), insoluble PA (r = 0.905, p = 0.0001) and NDIPA (r = 0.913, p = 0.0001). Acid detergent fibre difference was positively correlated with soluble PA (r = 0.796, p = 0.0001), insoluble PA (r = 0.976, p = 0.0001) and NDIPA (r = 0.974, p = 0.0001). Acid detergent lignin difference was positively correlated with soluble PA (r = 0.846, p = 0.0001), insoluble PA (r = 0.992, p = 0.0001) and NDIPA (r = 0.972, p = 0.0001). Neutral detergent insoluble nitrogen difference was positively correlated with soluble PA (r = 0.475, p = 0.0255), insoluble PA (r = 0.579, p = 0.0047) and NDIPA (r = 0.570, p = 0.0056). Acid detergent insoluble nitrogen difference was positively correlated with soluble PA (r = 0.798, p = 0.0001), insoluble PA (r = 0.969, p = 0.0001) and NDIPA (r = 0.979, p = 0.0001). Sodium sulphite has large effects on fibre values of PA-containing species. Our results suggest that the difference between fibre fractions prepared with and without the addition of sulphite to neutral detergent may be used to determine the effects of PA on protein solubility in detergents. © 1999 Society of Chemical Industry     

Application of near-infrared reflectance spectroscopy to chemical analysis of heterogeneous and botanically complex grassland samples

The potential of near-infrared reflectance spectroscopy (NIRS) for determining the chemical composition of heterogeneous, botanically complex semi-natural grassland herbage was assessed. Samples were collected over four consecutive years at different maturation stages and were analysed by chemical and NIRS procedures for crude protein, neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin and cellulose. A subset of samples was selected on the basis of spectral features in order to establish calibration equations, while the other samples were used for validation. The wavelengths selected by using multiple regression were similar to others previously reported. The ranges of correlation coefficients and standard errors of prediction, respectively, for the various components when NIRS and chemical procedures were compared were as follows: protein, 0·93-0·95 and 0·57-0·70; NDF, 0·92-0·93 and 2·06-2·37; ADF, 0·85-0·87 and 1·42-1·56; lignin, 0·90-0·94 and 0·45-0·59; cellulose, 0·82-0·86 and 1·27-1·45. The accuracy of predictions for these chemical components was similar to previously reported values.     

Effect of lignin linkages with other plant cell wall components on in vitro and in vivo neutral detergent fiber digestibility and rate of digestion of grass forages

The objective of this study was to correlate in vitro and in vivo neutral detergent fiber (NDF) digestibility (NDFD) with the chemical composition of forages and specific chemical linkages, primarily ester- and ether-linked para-coumaric (pCA) and ferulic acids (FA) in forages fed to dairy cattle. The content of acid detergent lignin (ADL) and its relationship with NDF does not fully explain the observed variability in NDFD. The ferulic and p-coumaric acid linkages between ADL and cell wall polysaccharides, rather than the amount of ADL, might be a better predictor of NDFD. Twenty-three forages, including conventional and brown midrib corn silages and grasses at various stages of maturity were incubated in vitro for measurement of 24-h and 96-h NDFD. Undigested and digested residues were analyzed for NDF, acid detergent fiber (ADF), ADL, and Klason lignin (KL); ester- and ether-linked pCA and FA were determined in these fractions. To determine whether in vitro observations of ester- and ether-linked pCA and FA and digestibility were similar to in vivo observations, 3 corn silages selected for digestibility were fed to 6 ruminally fistulated cows for 3 wk in 3 iso-NDF diets. Intact samples and NDF and ADF residues of diet, rumen, and feces were analyzed for ester- and ether-linked pCA and FA. From the in vitro study, the phenolic acid content (total pCA and FA) was highest for corn silages, and overall the content of ester- and ether-linked pCA and FA in both NDF and ADF residues were correlated with NDF digestibility parameters, reflecting the competitive effect of these linkages on digestibility. Also, Klason lignin and ADL were negatively correlated with ether-linked ferulic acid on an NDF basis. Overall, esterified FA and esterified pCA were negatively correlated with all of the measured fiber fractions on both a dry matter and an NDF basis. The lignin content of the plant residues and chemical linkages explained most of the variation in both rate and extent of NDF digestion but not uniformly among forages, ranging from 56 to 99%. The results from the in vivo study were similar to the in vitro data, demonstrating the highest total-tract aNDF digestibility (70%; NDF analysis conducted with α-amylase and sodium sulfite) for cows fed the corn silage with the lowest ester- and ether-linked pCA content in the NDF fraction. In this study, digestibility of forage fiber was influenced by the linkages among lignin and the carbohydrate moieties, which vary by hybrid and species and most likely vary by the agronomic conditions under which the plant was grown.     

Prediction of laboratory and in situ protein fractions in legume and grass silages using near-infrared reflectance spectroscopy

Legume and grass silage samples (n = 121) were collected from commercial forage testing laboratories (trial 1). Samples were dried at 55 degrees C for 48 h, ground, scanned on a near-infrared reflectance spectrophotometer, and analyzed for crude protein (CP), soluble CP, acid detergent fiber (ADF) CP, and neutral detergent fiber (NDF) CP by wet chemistry methods. Sixty samples were selected for calibration development, and the remaining samples were used for equation validation. Near-infrared reflectance spectroscopy accurately predicted the CP content of the silages (R2 = 0.96), but prediction of soluble CP, ADF CP, and NDF CP was markedly less accurate. The coefficients of determination and standard errors of calibration for CP, ADF CP, NDF CP (percentage of DM), and soluble CP (percentage of CP) were as follows (0.96 and 0.80, 0.77 and 0.24, 0.72 and 0.71, and 0.82 and 4.40). In a second study, legume and grass silage samples (n = 32) were dried at 55 degrees C and ground (2 mm). Duplicate dacron bags containing 5 g of silage were incubated in the ventral rumen of three ruminally cannulated cows for 0, 3, 6, 12, 24, 48, and 72 h. In situ protein fractions, including rapidly degraded protein, slowly degraded protein, undegradable protein, degradation rate, and rumen-undegradable protein, were determined. Original samples were reground (1 mm) and scanned. Previously defined near-infrared spectroscopy calibration procedures were conducted. Coefficients of determination for in situ CP fractions were R2 > 0.92 with the exception of degradation rate (R2 = 0.87). Data suggest that in situ protein fractions are better predicted by near-infrared reflectance spectroscopy than by laboratory protein fractions.     

Dietary fibre and components of the nitrogen-free extract of almond kernels

Determinations of neutral and acid detergent fibre residues (NDF and ADF), hemicellulose, cellulose and lignin in almond nuts (Prunus amygdalus) were carried out. The NDF content was about 5% while the crude fibre content was only approximately 2%. The composition of several components of nitrogen-free extract (NFE) such as soluble sugars, starch, gums and mucilages and pectins were also determined, and the results are discussed.     

Modification of in-vitro digestibility and cell-wall composition of cocksfoot,ryegrass and timothy by imazethapyr

Recent studies have shown that the compound imazethapyr (5-ethyl-2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)nicotinic acid) possesses growth regulatory activity and can be used to enhance nutritive value of grasses. However, little is known about possible effects of this material on fibre composition or potential fibre utilisation by ruminants. The objective of this research was to examine imazethapyr-treated cocksfoot (Dactylis glomerata L), ryegrass (Lolium perenne L × L multiflorum Lam), and timothy (Phleum pratense L) for possible treatment-induced changes in in-vitro digestibility and in concentrations of selected fibre constituents. Replicated field plots treated with imazethapyr at 0 (control) or 100 g ai ha^?1 during the vegetative (pre-elongation) stage of growth were harvested when controls were in the early stage of inflorescence emergence. Samples taken from treated plots 4 weeks post-treatment had higher in-vitro dry matter disappearance (IVDMD), lower neutral detergent fibre (NDF), lower acid detergent fibre (ADF), lower cellulose, lignin, and higher hemicellulose concentrations compared with controls. Imazethapyr treatment also reduced the concentration of p-coumaric acid in NDF, but had no effect on ferulic acid. The treatment effect on in-vitro NDF disappearance, however, was inconsistent among the grass species and was statistically non-significant (P = 0·10), implying that, under the conditions of this study, imazethapyr-related enhancements in IVDMD can be attributed primarily to a reduction in the amount of NDF and its associated constituents, as opposed to qualitative differences in NDF composition.     

Evaluation of tropical grasses for milk production by dual-purpose cows in tropical Mexico.

Two experiments using the Cornell Net Carbohydrate and Protein System were conducted to characterize the carbohydrate and protein fractions and corresponding rates of digestion of 15 tropical pasture grasses and to evaluate their ability to support milk production by dual-purpose cows. In the first experiment, ranges in carbohydrate and protein fractions of 15 grasses at 35 to 42 d of regrowth were: neutral detergent fiber (NDF) 63.5 to 74.9% of DM; permanganate lignin 4.7 to 7.8% of NDF; CP 5.5 to 11.9% of DM; and soluble protein 15.1 to 44.1% of crude protein (CP). The ranges of rates of digestion expressed as percent per hour were neutral detergent solubles (7.5 to 27.4); NDF (3.8 to 8.4); and neutral detergent insoluble protein (2.9 to 9.5). Predictions of the amount of milk that could be produced based on the amount of metabolizable energy supplied by the diet decreased 35% when NDF increased from 60 to 80%, and increased 88% when the rate of digestion of NDF increased from 3 to 6%/h. The milk production that could be sustained based on metabolizable protein in the diet doubled as CP increased from 4 to 12%. In the second experiment, nitrogen fertilization reduced NDF 7.3% and increased CP 84% without changing protein solubility, resulting in increased rumen nitrogen and metabolizable protein balances. With all forages, the Cornell Net Carbohydrate and Protein System predicted that availability of metabolizable protein would limit milk production. Predicted microbial growth was limited by ruminally available protein rather than by available carbohydrate.     

Apparent inhibition to digestion by lignin in normal and brown midrib stems

Lignin, a cell wall component, limits digestibility of plant cell walls. Brown midrib (bmr) mutants of forages have lignin with altered chemical composition compared with their normal counterparts. The objectives of this study were to determine if bmr lignin is more inhibitory to digestion than is normal lignin and if bmr has a consistent effect on rate of digestion across species and environments. Extent and rate of in-vitro cell wall digestion of normal and bmr stems of sorghum (Sorghum bicolor (L) Moench, two comparisons), millet (Pennisetum americanum (L) Leeke) and maize (Zea mays L, two comparisons) were determined. Samples were incubated in rumen fluid, and data were fitted with a first-order, nonlinear model to estimate concentrations of potentially digestible neutral detergent fibre (PDNDF), digestion rate of PDNDF, concentration of indigestible residue (IR), and lag time before digestion. The NDF, acid-detergent fibre (ADF), and acid-detergent lignin (ADL) analyses were conducted sequentially on undigested samples. The IR: ADL ratio was 37% greater for bmr than for normal plants, which indicates that bmr lignin inhibits digestion more than normal lignin per unit of lignin. Digestion rate of PDNDF was faster in bmr than in normal counterparts in one of the two sorghum comparisons (difference of 59%) and in the millet comparison (difference of 27%), but in neither maize comparison. The bmr mutants were lower than normal genotypes in NDF (9%) and ADL (47%) concentrations. The PDNDF concentration was 19% greater for bmr than for normal lines. Thus, decreased lignin concentration in bmr mutants increased the extent of NDF digestion but did not consistently increase the rate of digestion.     

Ryegrass or alfalfa silage as the dietary forage for lactating dairy cows

Renewed interest exists in using grass forages to dilute the higher crude protein (CP) and lower digestible fiber present in legumes fed to lactating dairy cows. A 3 x 3 Latin square feeding study with 4-wk periods was conducted with 24 Holstein cows to compare ryegrass silage, either untreated control or macerated (intensively conditioned) before ensiling, with alfalfa silage as the sole dietary forage. Ryegrass silages averaged [dry matter (DM) basis] 18.4% CP, 50% neutral detergent fiber (NDF), and 10% indigestible acid detergent fiber (ADF) (control) and 16.6% CP, 51% NDF, and 12% indigestible ADF (macerated). Alfalfa silage was higher in CP (21.6%) and lower in NDF (44%) but higher in indigestible ADF (26%). A lower proportion of the total N in macerated ryegrass silage was present as nonprotein N than in control ryegrass and alfalfa silages. Diets were formulated to contain 41% DM from either rye-grass silage, or 51% DM from alfalfa silage, plus high moisture corn, and protein concentrates. Diets averaged 17.5% CP and 28 to 29% NDF. The shortfall in CP on ryegrass was made up by feeding 7.6% more soybean meal. Intake and milk yields were similar on control and macerated ryegrass; however, DM intake was 8.3 kg/d greater on the alfalfa diet. Moreover, feeding the alfalfa diet increased BW gain (0.48 kg/d) and yield of milk (6.1 kg/d), FCM (6.8 kg/d), fat (0.26 kg/d), protein (0.25 kg/d), lactose (0.35 kg/d), and SNF (0.65 kg/d) versus the mean of the two ryegrass diets. Both DM efficiency (milk/DM intake) and N efficiency (milk-N/N-intake) were 27% greater, and apparent digestibility was 16% greater for DM and 53% greater for NDF and ADF, on the ryegrass diets. However, apparent digestibility of digestible ADF was greater on alfalfa (96%) than on ryegrass (average = 91%). Also, dietary energy content (estimated as net energy of lactation required for maintenance, milk yield, and weight gain) per unit of digested DM was similar for all three diets. Results of this trial indicated that, relative to ryegrass silage, feeding alfalfa silage stimulated much greater feed intake, which supported greater milk production.     

Protein fractionation byproduct from canola meal for dairy cattle

Fiber-protein is a byproduct arising from a process for fractionating high-quality protein from canola meal. The objective of this study was to evaluate the fiber-protein fraction by examining the chemical profiles, rumen degradation, and intestinal digestive characteristics and determining the nutritive value of the fiber-protein fraction as dietary components for dairy cattle in comparison with commercial canola meal and soybean meal. Available energy values were estimated based on National Research Council guidelines, whereas total true protein content potentially absorbable in the small intestine (DVE) were predicted using the predicted DVE/degraded protein balance (OEB) model. The results show that fiber-protein was a highly fibrous material [neutral detergent fiber (NDF): 556; acid detergent fiber (ADF): 463; acid detergent lignin: 241 g/kg of dry matter (DM)] compared with canola meal (NDF: 254; ADF: 212; acid detergent lignin: 90 g/kg of DM) due to the presence of a higher level of seed hulls in fiber-protein. Compared with canola meal, fiber-protein contained 90 g/kg of DM less crude protein (CP), 25% of which consisted of undegradable acid detergent-insoluble CP. Most of the ruminally undegradable nutrient components present in canola meal appeared to be concentrated into fiber-protein during the manufacturing process and, as a result, fiber-protein showed a consistently lower effective degradability of DM, organic matter, CP, NDF, and ADF compared with both canola meal and soybean meal. Available energy content in fiber-protein contained two-thirds of that of canola meal. The DVE was one-third that of soybean meal and one-fifth that of canola meal [DVE value: 58 vs. 180 (soybean) and 291 g/kg of DM (canola meal)]. The OEB value of fiber protein was positive and about half of that of soybean and canola meal [OEB value: 74 vs. 162 (soybean) and 137 g/kg of DM (canola meal)]. Fiber-protein can be considered as a secondary source of protein in ruminant feed.     

Carbohydrate Make Up of Huskey Barley

The chemical composition of two and six‐row huskey barley grown under Haryana agroclimatic conditions is reported. Two‐row varieties had slightly higher percentage of reducing sugars, sucrose and lignin, whereas protein, proanthocyanidins, starch, neutral detergent fibre (NDF), acid detergent fibre (ADF) and hemicellulose were higher in six‐row barleys. Malting significantly decreased the starch, sucrose and protein contents, while total soluble sugars, reducing sugars and maltose increased. The concommitant decrease in proanthocyanidins level is also desirable when barley is used for malting and brewing purposes. The variety RD2560 emerged to be superior for malting and brewing. The conduction of feeding trials and investigation of physico‐chemical properties of barley starch are suggested.     

Chemical composition of some forages and various residues from feeding value determinations

NDF, ADF, ‘cellulose’ and IVOMD residues, from feeding value determinations, were prepared from some forages, including straw, alkali-treated straw, grass and lucerne samples. The crude protein, cellulose, hemicellulose, uronic acid, Klason lignin, lignin and ash contents of these residues and the corresponding original forage samples were determined together with the relative composition of the neutral sugar constituents after acid hydrolysis. Cellulose, hemicellulose and Klason lignin were the main components in the NDF fractions but substantial amounts of crude protein (1–6%) also remained. Cellulose and Klason lignin were the main components in the ADF fractions, but 7–14% of the fractions was hemicellulose and 1–4% crude protein. Cellulose was the main component in the ‘cellulose’ fractions, but they also contained 8–13% hemicellulose, 2–7% Klason lignin and 2–11% ash. The composition of the IVOMD residues showed that cellulose and hemicellulose had been dissolved to about the same amounts (70–80%) and that most of the Klason lignin remained.     

Lax leaf maize: cell wall composition and nutritional value

Forage nutritive value, which comprises traits such as digestibility, fibre, lignin and protein content, is an important criterion for maize (Zea mays L) harvested as silage. Lines with a characteristic phenotype (‘lax leaf’) could be useful sources of genes for improved nutritive value in maize. A study was conducted to characterise the cell wall composition of the lax leaf line. Lax leaf inbreds and inbreds representing ‘normal’ maize were evaluated for cell wall neutral sugars, uronic acids, Klason lignin and phenolic acids in five tissues from the ear node and the internode above it. Acid detergent fibre (ADF) and neutral detergent fibre (NDF) and 48 h in vitro true digestibility (IVTD) were predicted using near‐infrared reflectance spectrophotometry (NIRS) calibrated with a subset of the scanned samples. Lax leaf inbred tissues had lower levels of ADF, NDF, lignin and xylose and were more digestible than tissues from the inbreds representing ‘normal’ maize. It was not known whether the lax leaf phenotype resulted from alterations in nutritive value traits or whether laxness and nutritive value traits are independent from one another. A second study was conducted to determine the nature of genetic control of the lax leaf character and to determine the genotypic relation between the lax leaf character and nutritive value. A recombinant inbred mapping population was developed from a cross between the lax leaf line and an inbred line with stiff upright leaves. Whole‐plant samples from each recombinant inbred line were evaluated for ADF, NDF, acid detergent lignin (ADL) and IVTD of dry matter using NIRS. Laxness, measured by number of broken leaves, was associated with lower nutritive value in this population (genetic correlations 0.16–0.34), which was contrary to expectation. Amplified restriction fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers were used to identify linkage groups associated with the lax leaf character, digestibility and fibre content. Several linkage groups were associated with both the lax leaf character and nutritive value. Where these characters were associated with the same linkage group, the lax leaf parent allele was associated with greater laxness but reduced nutritive value. The lax leaf parent allele was associated with increased nutritive value in linkage groups unassociated with the lax leaf character. While the lax leaf line may be a good source for alleles for improved nutritive value, selection for laxness will not likely be accompanied by improvement in forage quality. © 2000 Society of Chemical Industry     

The study of Clitoria Ternatea L. hay as a forage alternative in tropical countries. Evolution of the chemical composition at four different growth stages

The nutrients and the total carotenoids of samples of Clitoria rernatea L. hay harvested at four different stages of growth were analysed. Yields were also estimated. The results were: protein (N × 6.25), 23–19%; crude fibre, 29–38%; ether extract, 4.4–3.4%; Ash, 9–7%; neutral detergent fibre (NDF), 42–54%; acid detergent fibre (ADF), 38–47%; permanganate lignin, 14–16%; cellulose, 21–29%. Moreover, after being stored for 6 months, the samples have a carotenoids content of 587–400 mg kg^?1. All data refer to DM content. First year results reveal that the forage plant can give high annual yields of hay, (18–29 t ha^?1) with good palatability, readily accepted by cattle. In certain warm areas with low rainfall it could replace lucerne (alfalfa) Medicago sativa L.     

Effects of variety and crude protein content on nutrients and anti-nutrients in lentils (Lens culinaris)

Protein content was used as an indicator of environmental conditions for a study on varietal and environmental variation of proximate composition, minerals, amino acids and anti-nutrients of lentils. Four lentil varieties, each with three levels of protein content, were selected. Crude protein content ranged from 24.3% to 30.2%. Analysis of variance showed that both varietal and environmental conditions had a significant effect on starch content. Significant varietal differences were found in acid detergent fibre (ADF), neutral detergent fibre (NDF), fat, ash, calcium (Ca), copper (Cu), potassium (K), manganese (Mn), phosphorus (P) and Zinc (Zn). Protein showed significant effects on the amino acids, arginine and tryptophan. Variety had a significant effect on sucrose, stachyose, phytic acid, tannins and trypsin inhibitor activity (TIA). Major lentil components, protein and starch content were inversely correlated. K, Mn, P and Zn were negatively correlated with protein content. Tryptophan was the most deficient amino acid and the sulphur-containing amino acids were the second limiting amino acid in lentils. Raffinose was positively correlated with starch while negatively correlated with ADF.     

Freezing and Freezing-Thawing Cycles on Textural and Biochemical Changes of Meagre (Argyrosomus regius,L) Fillets During Further Cold Storage

The effects of freezing and freezing-thawing cycles during cold storage have been studied in meagre (Argyrosomus regius) fillets. Fillets were subjected to three conservation protocols: fresh, freezing at –20°C, and repeated freezing-thawing cycles. Fresh fillets were stored (4°C, 15 days), and the same protocol was followed for freezing and freezing-thawing after the freezing period. Freezing and freezing-thawing fillets were softer and presented lower water holding capacity than fresh, mostly attributable to collagen solubilization, and partial myofibrillar protein degradation. Cold storage (4°C) during 15 days caused softening in fresh and frozen fillets attributable to myofibrillar protein hydrolysis. Freezing-thawing cycles increased proteolysis, this leading to unacceptable softening even from early stages of further cold storage, and this was also revealed by SDS-PAGE.     

Comparisons of in situ dry matter disappearance kinetics of wheat forages harvested by various techniques and evaluated in confined and grazing steers

Ruminal in situ disappearance kinetics of forages are commonly evaluated in confined animals, but there have been relatively few attempts to evaluate disappearance kinetics of forage dry matter (DM) in grazing animals. Our objectives were 1) to evaluate the effects of harvest technique and sampling date on the in situ DM disappearance kinetics and nutritive value of wheat (Triticum aestiuum L.) forage, and 2) to compare the in situ disappearance kinetics of DM for these forages when the experimental steers were housed in confinement with those obtained from steers grazing wheat pasture. Wheat forage was harvested on three dates (March 6, March 27, and April 11, 2000). Sampling techniques evaluated on each date included three clipping techniques (whole plant, random pluck, and top half) and two evaluations of masticates (oven dried at 50 degrees C or lyophilized). There was an interaction of harvest technique and sampling date main effects for crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose, cellulose, lignin, and whole-plant ash. Disappearance kinetics of DM for these 15 forages were then evaluated by the in situ technique using five 393 +/- 54-kg crossbred steers consuming an alfalfa-based (Medicago sativa L.) diet in confinement, and subsequently, in five 448 +/- 49-kg crossbred steers grazing wheat pasture during March 2001. For fractions A, B, and C, potential extent, rate of disappearance (Kd), and effective ruminal degradability, linear regressions of values obtained for steers grazing wheat pasture on those obtained from confined cattle had significant slopes and exhibited high r2 statistics (>0.821). For fractions A and B, and Kd, the slope of these regression lines did not differ from unity, and the intercept did not differ from zero. For fraction C, potential extent of disappearance, and effective ruminal degradability, slopes were all equal to 1.19 and differed from unity. For effective degradability, deviation of the slope from unity can be explained, in part, on the basis of the passage rates used to calculate these values (0.035 and 0.062/h for confined and grazing steers, respectively). From a practical standpoint, the in situ disappearance kinetics of DM for these wheat forages did not appear to be altered substantially by evaluating them in grazing steers.