Fecal Neutral Detergent Fiber Research Articles

The Establishment of Fibrolytic Bacteria in the Foal Gastrointestinal Tract Is Related to the Occurrence of Coprophagy by Foals.

The consumption of maternal feces (coprophagy) is commonly observed in healthy foals and is a proposed contributor to microbial colonization of the foal's gastrointestinal tract (GIT). This study investigated the role of coprophagy in the establishment of fibrolytic bacteria in the foal GIT. Nine thoroughbred mares were dosed with chromic oxide, an indigestible marker, as a method to detect the occurrence of coprophagy by their foals. Foal fecal samples were collected from 12 h to 21 d after birth to measure chromic oxide and neutral detergent fiber (NDF) and to enumerate cellulolytic bacteria using culture-based techniques. Milk yield was estimated at 7 and 14 d postpartum. Coprophagy was detected as early as 3 d after birth and detected in all foals by 7 d of age. There were strong relationships between coprophagy and cellulolytic bacteria and NDF in foal feces at 7 d of age (r = 0.9703 and r = 0.7878, respectively; p < 0.05). Fecal NDF and chromic oxide concentrations were negatively related to milk yield (r = -0.8144 and r = -0.6966, respectively; p < 0.05), suggesting milk availability affected the incidence of coprophagy. Based on the relationships identified, maternal feces are an important source of fiber and live microbes for the foal, contributing to the development of the microbial community.

PSI-8 Digestible Energy and Metabolizable Energy Prediction Using Chemical Composition of Feces with no Dietary Information

Abstract The objective of the present study was to develop prediction equations for digestible energy (DE) and metabolizable energy (ME) in swine diets based on chemical compositions of feces with no dietary information. A total of 262 fecal samples obtained from growing pigs fed 27 diets from 4 experiments were used. The diets were based mainly on corn, soybean meal, and other plant-originated feed ingredients. In the digestibility experiments, feces and urine were quantitatively collected using the marker-to-marker procedure. The diet and fecal samples were analyzed for dry matter (DM), crude protein, ash, and neutral detergent fiber (NDF). Digestible energy in the 27 diets ranged from 2,907 to 4,374 kcal/kg DM and ME ranged from 2,774 to 3,983 kcal/kg DM. Fecal ash was positively correlated with DE (r = 0.81, P &amp;lt; 0.001) and ME (r = 0.66, P &amp;lt; 0.001) whereas fecal NDF was negatively correlated with DE (r = –0.66, P &amp;lt; 0.001) and ME (r = –0.74, P &amp;lt; 0.001). The energy prediction equations developed using fecal chemical components were: energy digestibility = 88.1 + 0.37 × ash – 0.28 × NDF (R2 = 0.57, P &amp;lt; 0.001); DE (kcal/kg DM) = 3,604 + 32.8 × ash – 11.1 × NDF (R2 = 0.71, P &amp;lt; 0.001); and ME (kcal/kg DM) = 4,077 + 15.7 × ash – 18.1 × NDF (R2 = 0.63, P &amp;lt; 0.001) where chemical components are expressed as % DM. In conclusion, energy digestibility, DE values, and ME values in swine diets are correlated with fecal ash and NDF concentrations and the energy values can be predicted using fecal ash and NDF concentrations without dietary information.

Analysis of fecal nutrients and particle size in captive proboscis monkeys (Nasalis larvatus) fed seasonal dietary foliage at a Japanese zoo.

One male and three female captive proboscis monkeys (Nasalis larvatus) were used as test animals to compare fecal nutrients after being fed seasonal foliage. Foliage and fecal samples were collected during three seasons (spring, summer, and winter). We analyzed crude ash (CA), ether extract (EE), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL). In addition to the above components, for the fecal samples, we examined total fecal nitrogen (TFN), nitrogen in fecal NDF (NDF-N), metabolic fecal nitrogen (MFN), and particle size distribution (MPS). Seasonal differences in foliage components were observed, with NDF and ADF being lowest in spring (p < 0.05). Fecal NDF and ADF also tended to be lowest in spring. Further, the distribution of fecal particle size indicated that MPS tended to increase in winter. The mean fecal NDF content (47.4%) for all three seasons measured in this study was as much as 1.3 times lower than previously reported values in free-ranging specimens. These data provide useful information that can be used to find some suitable food items for the endangered highly folivorous monkeys in captivity.

Short communication: Diet digestibility measured from fecal samples and associations with phenotypic and genetic merit for milk yield and composition

Selection for improved feed utilization is of high interest globally but is limited by the high cost of obtaining feed intake for individual cows and relies on indirect measures of feed efficiency. Supplementing selection with mechanistic measures of feed use could make selection for feed utilization more direct and effective. The objectives of this study were to evaluate fecal sampling as a method of determining digestive efficiency of individual cows and to evaluate associations of digestive efficiency with genetic and phenotypic merit for milk yield and composition. Fecal samples were obtained manually from the rectum of 90 Holstein cows in the morning, afternoon, and evening on a single date and composited across the day. The fecal samples were dried, ground, and stored. Diet and fecal neutral detergent fiber (NDF) were determined using the filter bag method, and indigestible NDF was determined in situ with a 12-d rumen incubation. Fecal NDF (60.1%) and indigestible NDF (41.9%) were higher than that from feed samples (14.2 and 35.9%, respectively). Total-tract digestibility was calculated using the marker ratio method. Total-tract dry matter (DM) digestibility averaged 66.0 ± 2.4% and total-tract NDF digestibility averaged 42.8 ± 3.0%. Higher milk fat percent and genetic merit for milk fat percent were associated with greater NDF and DM digestibility. Milk yield was negatively associated with NDF and DM digestibility. Fecal sampling is a feasible method to directly measure digestive efficiency, and substantial variation was observed among cows. Given significant between-cow variation and associations with milk fat percent and genetic merit for milk fat percent, potential selection for total-tract NDF digestibility estimated via fecal sampling warrants further exploration.

Fecal particle dry matter and fiber distribution of heifers fed ad libitum and restricted with low and high forage quality

Wet sieving of manure can be used as a means of evaluating the nutrient utilization of diets by dairy cows. A commercially available system for this analysis (Nasco Digestion Analyzer, Nasco, Fort Atkinson, WI; NDA) employs principles of wet sieving for on-farm assessment. The objective of this study was to evaluate effects of diet manipulations and sampling techniques on fecal particle dry matter (DM), neutral detergent fiber (NDF), and starch distribution on NDA sieves. Eight Holstein heifers (means ± SD; age 18.4 ± 0.6 mo and BW 457.2 ± 27.3 kg), were randomly assigned to a split-plot 4 × 3 incomplete Latin square experimental design with 18-d periods (15 d of adaptation and 3 d of sampling). Treatment rations differed in forage quality (high ADF <35%, low ADF >35%) and fiber content (high NDF >45%, low NDF <40%) and were offered to heifers for ad libitum and restricted intakes. Diets were fed to allow 900 to 1,000 g/d of body weight gain and fed once daily. Fecal grab samples were collected 0, 6, 12, and 18 h after feeding all 3 d of the sampling period, and the remaining feces was collected in the manner of total fecal collection to represent a daily composite sample. After wet sieving of each sample using a NDA kit, the retained material on sieves was dried and analyzed for DM, NDF, and starch content. Sampling day and feeding regimen did not affect distributions of nutrients. Distributions of total fecal particle DM were greater for high forage quality and high fiber content diets (14.66 to 20.37% of sample DM). The NDF content in retained material decreased with decreasing sieve size (from 89.81 to 86.86%) and was not affected by forage quality and fiber content, whereas NDF retained on NDA (% DM) followed the same pattern as the retained particle DM weight. Starch content in retained material was below 0.5% in the majority of diets. Average retained fecal particle DM and NDF content varied depending on the time after feeding, resulting in the large differences between grab fecal samples and a daily total composite sample. However, average values of retained particle DM and NDF weight for all sampling time points were similar to ones from total daily composite sample.

Effect of Limit-Fed Diets With Different Forage to Concentrate Ratios on Fecal Bacterial and Archaeal Community Composition in Holstein Heifers.

Limit-feeding of a high concentrate diet has been proposed as an effective method for improving feed efficiency and reducing total manure output of dairy heifers; meanwhile the effects of this method on hindgut microbiota are still unclear. This study investigated the effects of a wide range of dietary forage:concentrate ratios (F:C) on the fecal composition of bacteria and archaea in heifers using next-generation sequencing. Four diets with different F:C (80:20, 60:40, 40:60, and 20:80) were limit-fed to 24 Holstein heifers, and the fecal fermentation parameters and bacterial and archaeal communities were investigated. With increasing dietary concentrate levels, the fecal dry matter output, neutral detergent fiber (NDF) content, and proportion of acetate decreased linearly (P < 0.01), while the fecal starch content and proportions of propionate, butyrate, and total branched-chain volatile fatty acids (TBCVFAs) were increased (P ≤ 0.05). An increased concentrate level linearly increased (P = 0.02) the relative abundance of Proteobacteria, and linearly decreased (P = 0.02) the relative abundance of Bacteroidetes in feces. At the genus level, the relative abundance of unclassified Ruminococcaceae and Paludibacter which may have the potential to degrade forage decreased linearly (q ≤ 0.02) with increasing dietary concentrate levels, while the relative abundance of Roseburia and Succinivibrio which may be non-fibrous carbohydrate degrading bacteria increased linearly (q ≤ 0.05). Some core microbiota operational taxonomic units (OTUs) also showed significant association with fecal VFAs, NDF, and/or acid detergent fiber (ADF) content. Meanwhile, the relative abundance of most detected taxa in archaea were similar across different F:C, and only Methanosphaera showed a linear decrease (P = 0.01) in high concentrate diets. Our study provides a better understanding of fecal fermentation parameters and microbiota under a wide range of dietary F:C. These findings support the potential for microbial manipulation by diet, which could enhance feed digestibility and relieve environmental problems associated with heifer rearing.

An analysis of dietary fiber and fecal fiber components including pH in rural Africans with colorectal cancer.

Background/AimsColorectal cancer (CRC) is now a major public health problem with heavy morbidity and mortality in rural Africans despite the lingering dietary fiber-rich foodstuffs consumption. Studies have shown that increased intake of dietary fiber which contribute to low fecal pH and also influences the activity of intestinal microbiota, is associated with a lowered risk for CRC. However, whether or not the apparent high dietary fiber consumption by Africans do not longer protects against CRC risk is unknown. This study evaluated dietary fiber intake, fecal fiber components and pH levels in CRC patients.MethodsThirty-five subjects (CRC=21, control=14), mean age 45 years were recruited for the study. A truncated food frequency questionnaire and modified Goering and Van Soest procedures were used.ResultsWe found that all subjects consumed variety of dietary fiber-rich foodstuffs. There is slight preponderance in consumption of dietary fiber by the control group than the CRC patients. We also found a significant difference in the mean fecal neutral detergent fiber, acid detergent fiber, hemicellulose, cellulose and lignin contents from the CRC patients compared to the controls (P<0.05). The CRC patients had significantly more fecal pH level than the matched apparently healthy controls (P=0.017).ConclusionsThe identified differences in the fecal fiber components and stool pH levels between the 2 groups may relate to CRC incidence and mortality in rural Africans. There is crucial need for more hypothesis-driven research with adequate funding on the cumulative preventive role of dietary fiber-rich foodstuffs against colorectal cancer in rural Africans “today.”

Abstract A19: Dietary-fiber and fecal fiber contents including pH in rural Africans with colorectal cancer

Abstract Studies have shown improved/increased intake of dietary fiber and low fecal pH are associated with a lowered risk for colorectal cancer. This study aimed to compare dietary fiber intake, fecal neutral detergent fiber (NDF) content, acid detergent fiber (ADF), cellulose, hemicellulose, lignin and fecal pH level of colorectal cancer patients and matched apparently healthy control group in rural Africans in Zaria, Nigeria. Twenty-one subjects of mean age 44.7 years who are diagnosed with colorectal cancer by histology and 14 apparently healthy matched control groups with mean age 45.2 years were recruited for this study. A predefined semi structured food frequency questionnaire (FFQ) was used to access the dietary fiber intake by the subjects. The fecal NDF content was analyzed by extracting 1 g of fecal sample with a mixture of ethanol/ether and refluxed with decalin and sodium sulphite. The extract was suctioned and washed with acetone to yield the total NDF. The NDF was refluxed with an acid detergent solution and dried overnight to yield the ADF. The differences in the NDF and ADF gave the total hemicelluloses. The differences in the weight of the ADF post-treatment with permanganate solution yielded the total lignin. The differences in weight of the permanganate residue post-treatment with 72% Sulphuric acid gave the cellulose content. A pH meter calibrated with buffers of pH 4 and 7 was used to measure the fecal pH of all the subjects. Results from the FFQ show all subjects consumed variety of dietary fiber food in significant amount. However, there was a significant difference in the fecal NDF, ADF, hemicellulose, lignin and cellulose contents from the colorectal cancer patients when compared with the control group (p &amp;lt;0.05). So also was there a significant difference in fecal pH between the two groups (p &amp;lt;0.05). Consumption of dietary fiber rich foodstuffs alone may not be adequate for prevention against colorectal cancer incidence in some rural Africans in Zaria. There is a need to look into other associating factors which, might have been contributing to colorectal cancer incidence/increase in rural African population. Citation Format: Mohammed Faruk, Sani Ibrahim, Ahmed Adamu, Abdulmumini Hassan Rafindadi, Yahaya Ukwenya, Yawale Iliyasu, Abdullahi Adamu, Mohammed Sani Shehu, Danladi Amodu Ameh, Sirajo Mohammed Aminu, Saad Aliyu Ahmed, John Idoko, Atara Ntekim, Aishatu Maude Suleiman, Khalid Zahir Shah, Kasimu Umar Adoke. Dietary-fiber and fecal fiber contents including pH in rural Africans with colorectal cancer [abstract]. In: Proceedings of the AACR International Conference: New Frontiers in Cancer Research; 2017 Jan 18-22; Cape Town, South Africa. Philadelphia (PA): AACR; Cancer Res 2017;77(22 Suppl):Abstract nr A19.

Short communication: The effects of morning compared with evening feed delivery in lactating dairy cows during the summer

Delivering fresh feed in the evening is a management strategy sometimes used during periods of heat stress, but previous experiments have observed that night feeding increased feed intake during the 2 h after feeding and did not change intake during the overnight period. The objective of this study was to determine the effect of night feeding on daily rhythms of the dairy cow during the summer season. Twelve Holstein cows were used in a crossover design with 14-d periods. An automated system recorded the timing of feed intake over the last 7 d of each period. Treatments were ad libitum feeding with fresh feed delivery 1×/d at 0830 h or 2030 h. Milk yield and composition were not changed by treatment, but night feeding decreased the concentration of preformed fatty acids in milk fat. Night feeding decreased feed intake 1.7 kg/d, and decreased total-tract dry matter and neutral detergent fiber (NDF) digestibility by 0.7 and 0.8 percentage units, respectively. The amount of feed consumed in the first 2 h after feeding was 64% greater with night feeding, but intake did not differ between treatments during the night or early afternoon. A treatment by time of day interaction was observed for fecal NDF and indigestible NDF concentration and plasma glucose, insulin, and urea concentrations. Night feeding resulted in an increase in plasma insulin after feeding, which decreased plasma glucose. The daily rhythm of core body temperature was entrained by treatment, with the phase shifted and the amplitude decreased by night feeding indicating alteration of the central clock. In conclusion, feeding cows once per day in the evening during the summer caused a similar increase in feed intake and plasma insulin after feeding as previously observed during non-heat stress seasons. Night feeding also decreased intake and total-tract digestibility. The daily pattern of feed intake and other behaviors should be considered before initiation of night feeding.

The effects of feeding a partial mixed ration plus a top-dress before feeding on milk production and the daily rhythm of feed intake and plasma hormones and metabolites in dairy cows

Total mixed rations (TMR) are commonly fed to dairy cows with a goal of reducing ruminal acidosis, but the daily pattern of feed intake has major implication for rumen fermentation and postabsorptive physiology. Generally there is low feed intake during the overnight period and high intake after feeding and during the afternoon. The objective of this study was to determine if feeding a partial mixed ration (PMR) plus a high starch top-dress before feeding of the PMR would improve production and modify key daily rhythms. The top-dress was fed before feeding as ruminal starch is at a nadir and amylolytic capacity is expected to be low. Ten Holstein cows were used in a crossover design with 14-d periods. Cows were housed in tie stalls with feed tubs and feed weight was recorded every 10 s for observation of feeding behavior. Treatments were a control TMR fed once per day at 0900 h or a partial mixed ration plus a top-dress (PMR+TD). The top-dress was fed at 9.5% of DMI offered at 0800 h and contained steamflaked corn, canola meal, and nonprotein nitrogen. No interaction was observed between treatment and milking time. Milk yield tended to be decreased 1.1 kg and milk fat yield was decreased 70 g/d by PMR+TD. Milk fat preformed fatty acids were decreased and no effect was observed of treatment on trans-10 C18:1 or other indicators of biohydrogenation-induced milk fat depression. No effect was observed of treatment on meal parameters including meal size and number. The PMR+TD increased total-tract neutral detergent fiber (NDF) digestibility by 1.2 percentage points. Treatment changed the daily pattern of fecal NDF and indigestible NDF, indicating changes in rumen function over the day. No effect was observed on plasma glucose, but the amplitude of the daily rhythm of insulin was increased by PMR+TD. The PMR+TD also increased plasma nonesterified fatty acids and decreased blood urea nitrogen across the day. Core body temperature is entrained by the central biological clock and its phase was advanced 42 min and its amplitude slightly increased by PMR+TD. In conclusion, the top-dress appears to have modified the central circadian rhythm and plasma insulin and blood urea nitrogen. This demonstrates that timing of feeding can be used to manage daily rhythms of the dairy cow, although the optimal timing requires further investigation.

Methodological considerations for the use of faecal nitrogen to assess diet quality in ungulates: The Alpine ibex as a case study

Faecal indices are used to describe spatiotemporal patterns of diet quality in wild herbivores, and near infrared spectroscopy methods (NIRS) distinctively reduce costs and labour compared to conventional chemical analyses. In this study we compared the prediction accuracy of faecal nitrogen (N), ash and fibrous fractions of a laboratory instrument (NIRS) with that of a lightweight portable instrument (VisNIRS) using faecal samples of Alpine ibex (Capra ibex). We then compared how different indices based on faecal N and fibrous fractions were able to detect the expected temporal trend and difference between sexes in diet quality, and verified whether the presumably lower accuracy of NIRS and VisNIRS (compared to wet chemistry) influenced the ability of indices to detect such trends. The laboratory NIRS was more accurate than the portable VisNIRS, especially for fibrous fractions. Predicted data from both instruments clearly identified the temporal trend identified by chemically analysed data, but only NIRS identified the small difference between sexes. Expressing faecal N as a proportion of organic matter (OM) or neutral detergent fibre (NDF) improved the power of the index as compared to expressing it as a proportion of dry matter (DM), irrespective of the method used to estimate the data. Faecal NDF contents followed the patterns expected from the variation of faecal N, while faecal acid detergent fibre (ADF) and especially lignin (ADL) followed contradictory patterns, which might be due to a selection of different forage sources rather than to changing quality of a homogenous forage source. We conclude that expressing faecal N as a proportion of OM is advised with wild herbivores faeces, where ash content can be biased by accidental soil contamination or ingestion. Faecal fibrous fractions are useful to complement faecal N and to avoid simplified interpretations of the results. For this purpose, NIRS methods can be extremely useful to predict multiple indices on large numbers of samples. VisNIRS portable instruments might be unable to detect subtle biological patterns in small numbers of samples. However, developing procedures for portable instruments outside laboratory facilities might further improve practicability, cost effectiveness, and, through allowing on-field predictions on large numbers of samples, power of statistical testing of diet quality indices.

Predictability of growth performance in feedlot cattle using fecal near infrared spectroscopy

Near-infrared spectroscopy (NIRS) was used to predict nutrients and apparent total tract digestibility (aTTD) of nutrients and gross energy (GE) using 282 dried ground fecal samples collected monthly over 13 mo from the pen floor of six feedlots in southern Alberta. Mixed-model regression was used to examine relationships among fecal composition, digestibility, dry matter intake (DMI), average daily gain (ADG), and gain to feed ratio (G:F). Lower (P < 0.01) fecal starch, greater (P ≤ 0.04) fecal neutral detergent fiber, and greater (P ≤ 0.01) aTTD of dry matter (DM), organic matter (OM), starch, and GE were observed in cattle fed tempered versus dry-rolled barley, with no differences in DMI, ADG, or G:F. Compared with cattle fed barley, those fed a wheat–barley grain mixture had greater (P ≤ 0.02) fecal starch and aTTD of DM, OM, as well as greater ADG, and G:F. Heifers had a lower (P ≥ 0.05) aTTD of DM and GE than steers. A quadratic relationship was observed between fecal starch and G:F, with sex and av...

The effects of feeding rations that differ in fiber and fermentable starch within a day on milk production and the daily rhythm of feed intake and plasma hormones and metabolites in dairy cows

A daily pattern of feed intake, milk synthesis, and plasma metabolites and hormones occurs in dairy cows fed a total mixed ration once or twice a day. The objective of this study was to determine if feeding multiple rations within a day, complementing these rhythms, would improve milk production. Twelve Holstein cows were used in a replicated 3×3 Latin square design with 21-d periods. Cows were housed in tie stalls with feed tubs, and feed weight was recorded every 10 s for observation of feeding behavior. Rations were a low fiber and high fermentable starch ration [LFHS; 27.4% neutral detergent fiber (NDF) and 31.7% starch based on 55.7% corn silage and 14.1% steam-flaked corn], a high fiber and low fermentable starch ration (HFLS; 31.7% NDF and 22.3% starch based on 44% corn silage, 26.3% alfalfa haylage, and no steam-flaked corn), and a total mixed ration that was a 1:3 ratio of LFHS and HFLS (30.7% NDF, 24.5% starch). The control treatment (CON) cows were fed the total mixed ration at 0700h, the high/low treatment (HL) fed HFLS ration at 0700h and LFHS ration at 2200h, and the low/high (LH) treatment fed LFHS ration at 0700h and HFLS ration at 1100h (LFHS and HFLS rations fed at a 1:3 ratio). No effect was found of treatment on daily milk, but LH decreased milk fat concentration and yield compared with HL (0.2 percentage units and 0.24kg, respectively). Daily dry matter and NDF intake and total-tract digestibility did not differ between treatments. The HL treatment reduced intake at the morning-conditioned meal after feeding and reduced intake before the evening feeding. A treatment by time of day interaction was found for fecal NDF and indigestible NDF concentration, blood urea nitrogen (BUN), plasma insulin, and fatty acid concentration, and body temperature. The CON and LH treatments increased the daily amplitude of fecal NDF by 1.0 and 1.1 percentage units compared with HL. Plasma insulin was higher in HL than CON at 0100 and 0400h, but lower at 1300 and 1900h. Plasma fatty acids were higher for CON than HL at 0700h and HL was lower than LH at 0400 and 1900h. Plasma BUN was higher for HL than control at 0100h, but lower at 1000h. Body temperature in CON and HL treatments followed a similar diurnal pattern, whereas body temperature for LH was lower than that of HL treatment at 1300 and 2300h. No daily rhythm was found of fecal indigestible NDF concentration, plasma glucose, or fatty acids detected in the HL treatment, and the amplitude of plasma insulin and BUN was lower for HL compared with CON (70 and 60% decrease, respectively). In conclusion, feeding 2 rations that differ in fiber and fermentable starch modifies diurnal rhythms in dairy cows. Furthermore, feeding a high fiber and low fermentable starch ration during the high intake period of the day may stabilize nutrient absorption across the day.

0457 Characterization of the variation in the daily excretion of fecal constituents and digestibility predictions in beef cattle fed feedlot diets using near infrared spectroscopy

Six heifers were individually housed and assigned to once (FF1) or twice (FF2) daily feeding regimes over backgrounding and finishing periods. Following adaptation, total faecal collections were conducted at 4-h intervals and at 24-h intervals over 4 d, and near-infrared spectroscopy (NIRS) was used to predict faecal organic matter (OM), starch, nitrogen (N), neutral detergent fibre (NDF), acid detergent fibre (ADF), and acid detergent lignin (ADL). At each interval, NIRS calibrations were used to estimate faecal constituents and ADL to calculate apparent (aTTD) and estimated (eTTD) total tract digestibility. Faecal dry matter (DM) (%), NDF, and ADF varied among 4-h interval samples in the backgrounding period and faecal DM, starch, NDF, ADF, and ADL in the finishing period. Faecal starch was able to predict aTTD during both feeding periods (backgrounding: R 2 = 0.96, P < 0.01; finishing: R 2 = 0.98, P < 0.01). The NIRS calibrations for predicting aTTD using the 4-h interval samples or the 4-d-24-h composite were least accurate for NDF and ADF. Most 4-h interval samples could be used to predict eTTD of nutrients, and aside from starch in the finishing period, there were no differences in eTTD using faecal samples collected over 4-h intervals versus those collected over 4 d. Spot faecal samples collected at any time point from multiple cattle have the potential to predict digestibility. Timing of sampling after feeding must be standardized to predict starch digestibility during the finishing period, with samples between 0- 4ha nd 8-16 h generating estimates of both starch concentration and digestibility that were closest to that derived from 4-d-24-h composite samples.

Evaluation of winter food quality and its variability for red deer in forest environment: overwintering enclosures vs. free-ranging areas

AbstractPopulations of European ungulates have grown substantially over recent decades, resulting in considerable environmental and socio-economic impacts. Availability and quality of natural and supplemental food sources are among the main factors driving their population dynamics. Detailed knowledge of food quality of management-targeted species is therefore of primary importance for their successful management. The main aim of this study was to evaluate winter food quality and its variability for an important ungulate species in the Czech Republic - i.e. red deer, using faecal indices (faecal nitrogen, faecal acid detergent fibre, faecal neutral detergent fibre) and near infrared reflectance spectroscopy. We compared food quality for red deer and its possible differences between overwintering enclosures (i.e. fenced areas where red deer spend harsh winter conditions) and neighbouring unfenced free-ranging areas within two study areas. The results obtained showed that winter food quality and its variability for red deer are of different quality and variability in the overwintering enclosure and neighbouring free-ranging area. The observed differences in concentrations and amounts of variation of faecal indices are most probably related to animal densities at individual study areas. Wildlife managers should therefore keep animals in overwintering enclosures at moderate densities and to provide high quality forage to all individuals in order to balance nutrition of both the individuals inside and outside the enclosures. Nevertheless, further studies are needed in order to provide deeper knowledge on red deer food quality and its variability in space and time.

Characterization of the variation in the daily excretion of faecal constituents and digestibility predictions in beef cattle fed feedlot diets using near-infrared spectroscopy

Six heifers were individually housed and assigned to once (FF1) or twice (FF2) daily feeding regimes over backgrounding and finishing periods. Following adaptation, total faecal collections were conducted at 4-h intervals and at 24-h intervals over 4 d, and near-infrared spectroscopy (NIRS) was used to predict faecal organic matter (OM), starch, nitrogen (N), neutral detergent fibre (NDF), acid detergent fibre (ADF), and acid detergent lignin (ADL). At each interval, NIRS calibrations were used to estimate faecal constituents and ADL to calculate apparent (aTTD) and estimated (eTTD) total tract digestibility. Faecal dry matter (DM) (%), NDF, and ADF varied among 4-h interval samples in the backgrounding period and faecal DM, starch, NDF, ADF, and ADL in the finishing period. Faecal starch was able to predict aTTD during both feeding periods (backgrounding: R2 = 0.96, P &lt; 0.01; finishing: R2 = 0.98, P &lt; 0.01). The NIRS calibrations for predicting aTTD using the 4-h interval samples or the 4-d–24-h composite were least accurate for NDF and ADF. Most 4-h interval samples could be used to predict eTTD of nutrients, and aside from starch in the finishing period, there were no differences in eTTD using faecal samples collected over 4-h intervals versus those collected over 4 d. Spot faecal samples collected at any time point from multiple cattle have the potential to predict digestibility. Timing of sampling after feeding must be standardized to predict starch digestibility during the finishing period, with samples between 0–4 h and 8–16 h generating estimates of both starch concentration and digestibility that were closest to that derived from 4-d–24-h composite samples.

Prediction of rumen fiber pool in cattle from dietary, fecal, and animal variables

Feed intake control in ruminants is based on the integration of physical constraints and metabolic feedbacks. Physical constraints are related to the fill caused by the weight or volume of digesta in the reticulo-rumen. The amount of neutral detergent fiber (NDF) in the rumen (RNDF) may be used as an indicator of rumen fill. The objective of this study was to develop equations predicting RNDF from diet and animal characteristics using a meta-analysis technique. A treatment mean data set (n=314) was obtained from 84 studies, in which rumen pool size and diet digestibility were determined in lactating cows (n=231) or growing cattle (n=83). The data were analyzed using linear and nonlinear mixed models. Intake, rumen pool size, and fecal output of NDF were scaled to body weight (BW)1.0. Due to the heterogeneous nature of dietary NDF, predictions of RNDF based on NDF intake were not precise. Predictions were markedly improved by dividing NDF into potentially digestible and indigestible fractions, because rumen turnover time of indigestible NDF was 2.7 times longer than that of potentially digestible NDF. At equal NDF intake, RNDF was negatively associated with dietary crude protein concentration and positively with the proportion of concentrate in the diet. Models based on fecal NDF output generally performed better than those based on NDF intake, probably because the effects of intrinsic characteristics of dietary cell walls and associative effects of dietary components collectively influence fecal NDF output. The model based on fecal NDF output was improved by including dietary concentration of forage NDF in the model, reflecting slower turnover of forage NDF compared with concentrate NDF. The curvilinear relationship between fecal NDF output and RNDF could be described by a quadratic, Mitscherlich, or power function equation, which performed better than the quadratic or Mitscherlich equation. In addition to fecal NDF output and dietary concentration of forage NDF, animal and forage type had significant effects on RNDF. At the same fecal NDF output, growing cattle had a smaller RNDF than dairy cattle. Increased proportion of alfalfa or corn silages in forage decreased RNDF and increased proportion of tropical forages decreased it. It is concluded that RNDF can be predicted precisely from intake or fecal output data, and that predicted RNDF can be a useful tool in understanding the interplay between physical and metabolic factors regulating feed intake in ruminants.

Photosynthetic pigments estimate diet quality in forage and feces of elk (Cervus elaphus)

Understanding the nutritional dynamics of herbivores living in highly seasonal landscapes remains a central challenge in foraging ecology with few tools available for describing variation in selection for dormant versus growing vegetation. Here, we tested whether the concentrations of photosynthetic pigments (chlorophylls and carotenoids) in forage and feces of elk (Cervus elaphus L., 1785) were correlated with other commonly used indices of forage quality (digestibility, energy content, neutral detergent fiber (NDF), and nitrogen content) and diet quality (fecal nitrogen, fecal NDF, and botanical composition of the diet). Photosynthetic pigment concentrations were strongly correlated with nitrogen content, gross energy, digestibility, and NDF of elk forages, particularly in spring. Winter and spring variation in fecal pigments and fecal nitrogen was explained with nearly identical linear models estimating the effects of season, sex, and day-of-spring, although models of fecal pigments were consistently a better fit (r2adjusted = 0.379–0.904) and estimated effect sizes more precisely than models of fecal nitrogen (r2adjusted = 0.247–0.773). A positive correlation with forage digestibility, nutrient concentration, and (or) botanical composition of the diet implies fecal photosynthetic pigments may be a sensitive and informative descriptor of diet selection in free-ranging herbivores.

The influence of habitat on body size and tooth wear in Scottish red deer (Cervus elaphus)

Body size has profound implications for ecology and life-history traits of mammalian species. Tooth wear is an indicator of food-processing investment and diet properties, with fitness consequences through differences in comminution efficiency, nutrient gain, and senescence. We investigate the relationships between mandible length (a proxy of skeletal body size), molar dentine thickness (a measure of tooth wear), and faecal neutral detergent fibre with residual ash (NDF–ash, a combined proxy of fibre and mineral components in the diet) in 874 male and female red deer (Cervus elaphus L., 1758) from 21 locations in moorland and woodland habitats across Scotland. Significant differences in mandible length occurred between habitats: woodland deer having larger mandibles than moorland deer. Within habitats, larger mandibles were related to higher rates of dentine wear, suggesting increased body size was associated with greater intake and processing of food. Both dentine wear and faecal NDF–ash were higher in moorland deer than in woodland deer, suggesting that fibre and (or) mineral abrasives in the diet may have contributed towards habitat differences in dentine wear. Between habitats, higher dentine wear was not associated with larger mandibles, in contrast to the relationship within habitats, indicating the precedence of additional environmental factors between habitats.

The effects of feeding time on milk production, total-tract digestibility, and daily rhythms of feeding behavior and plasma metabolites and hormones in dairy cows

The timing of feed intake entrains circadian rhythms regulated by internal clocks in many mammals. The objective of this study was to determine if the timing of feeding entrains daily rhythms in dairy cows. Nine Holstein cows were used in a replicated 3×3 Latin square design with 14-d periods. An automated system recorded the timing of feed intake over the last 7 d of each period. Treatments were feeding 1×/d at 0830h (AM) or 2030h (PM) and feeding 2×/d in equal amounts at 0830 and 2030h. All treatments were fed at 110% of daily intake. Cows were milked 2×/d at 0500 and 1700h. Milk yield and composition were not changed by treatment. Daily intake did not differ, but twice-daily feeding tended to decrease total-tract digestibility of organic matter and neutral detergent fiber (NDF). A treatment by time of day interaction was observed for feeding behavior. The amount of feed consumed in the first 2h after feeding was 70% greater for PM compared with AM feeding. A low rate of intake overnight (2400 to 0500h; 2.2±0.74% daily intake/h, mean ± SD) and a moderate rate of intake in the afternoon (1200 to 1700h; 4.8±1.1% daily intake/h) was noted for all treatments, although PM slightly reduced the rate during the afternoon period compared with AM. A treatment by time of day interaction was seen for fecal NDF and indigestible NDF (iNDF) concentration, blood urea nitrogen, plasma glucose and insulin concentrations, body temperature, and lying behavior. Specifically, insulin increased and glucose decreased more after evening feeding than after morning feeding. A cosine function within a 24-h period was used to characterize daily rhythms using a random regression. Rate of feed intake during spontaneous feeding, fecal NDF and iNDF concentration, plasma glucose, insulin, NEFA, body temperature, and lying behavior fit a cosine function within a 24-h period that was modified by treatment. In conclusion, feeding time can reset the daily rhythms of feeding and lying behavior, core body temperature, fecal NDF and iNDF concentration, and plasma blood urea nitrogen, glucose, and insulin concentration of dairy cows, but has no effect on daily DMI and milk production.