Variation In Forage Quality Research Articles

Informing the prediction of forage quality of Mediterranean grasslands using hyperspectral reflectance: Concentration vs content, phenology, and generalisation of models

ContextRemote sensing has shown potential to provide accurate and real-time information on grassland forage quality, crucial for the management of livestock systems. However, there are still uncertainties that must be considered to make models reliable and practical. A source of discrepancy regards the measurement unit describing forage quality variables, namely either mass-based concentration (%) or mass per surface area content (kg ha−1). Furthermore, phenological patterns largely influence grassland reflectance and have a strong impact on model accuracy. Also, the generalisation of empirical models in heterogeneous grasslands can hinder their applicability. Objectives1) Assess the suitability of retrieving forage quality parameters as concentration (%) versus content (kg ha−1). 2) Investigate the performance of multitemporal compared to phenophase-specific models. 3) Evaluate the generalisation ability of the models. MethodsSamples were collected from five farms to determine Dry Matter Yield (DMY) and both, concentration (%) and content (kg ha−1) of forage quality variables including crude protein (CP), neutral and acid detergent fibre (NDF, ADF), and enzyme digestibility of organic matter (EDOM). The relationship between forage quality variables and DMY were analysed by Pearson Correlations and Principal Component Analysis. Reflectance was recorded with a FieldSpec spectroradiometer. Partial Least Squares Regression (PLSR) was used to explore the relationship between forage variables and reflectance. ResultsThe forage quality variables were strongly correlated to DMY when expressed as content (kg ha−1) r>0.83 but not when expressed as concentration (%). For the best predicted variables, CP and NDF, the results of the PLSR models indicated better performance in concentration-based estimation. CP% was the best predicted variable (R2cv=0.8, NRMSEcv=9.8 %). Multitemporal models showed overall higher performance (CP%, R2cv=0.81) than phenophase-specific models (CP%, R2cv=0.60 green, R2cv=0.70 green-senescent and R2cv<0 senescent grasslands). The generalisation ability was low and varied among farms (R2test 0–0.60). ConclusionsThe use of concentration (%) is more accurate and representative of forage quality than content (kg ha−1), which seemed redundant with DMY and misleading from the true nutritive value for livestock.Multitemporal models performed better than phenophase-specific models due to their larger range of values. The ability to predict forage quality in senescent grasslands is low. The usefulness of the models is context-dependent, and their application requires knowledge of the limitations and status of the grasslands. Efforts must be directed toward improving the generalisation ability through the development of models calibrated with larger and more diverse datasets.

Linking summer nutrition to behavior and performance of black‐tailed deer

AbstractMany large‐herbivore populations are regulated at least in part by bottom‐up forces, and thus relationships between herbivores and their habitat are of fundamental importance to wildlife managers. Variation in nutritional resources—and how herbivores respond to that variation—influences rates of nutrient intake, which directly affect nutritional condition, pregnancy rates, timing of parturition, offspring birth mass, and survival. Accordingly, nutrition‐focused research holds great potential for uncovering the mechanisms that govern population performance of large herbivores and for assessing the nature and magnitude of bottom‐up limitations. We quantified relationships between the foodscape (i.e., spatiotemporal variation in forage quality and abundance) in southwestern Oregon, USA, and black‐tailed deer (Odocoileus hemionus columbianus) behavior and performance, with a focus on the influence of maternal nutrition on fawn survival. We hypothesized that black‐tailed deer performance (i.e., fawn birth mass and survival) is influenced by the availability of high‐quality forage during spring and summer and patterns of foodscape use exhibited by individual deer. From 2016–2023 we monitored movement and survival of adult female black‐tailed deer and their offspring. We also conducted intensive vegetation sampling and used generalized additive modeling to map the foodscape available to deer in spring and summer. Suitable forage biomass (i.e., maximum biomass of forage that together exceeded quality thresholds for supporting one fawn) was highly variable across space and time, and our top foodscape model explained 70% of the variation in suitable biomass (adjusted R2 = 0.70). We observed a strong, positive relationship between use of the foodscape by maternal females prior to parturition and fawn birth mass. Although maternal foodscape use after parturition did not influence the probability of fawn survival, survival increased with increasing birth mass. These results suggest that the effects of nutrition on fawn survival in our study system are indirectly mediated by maternal behavior (i.e., use of the foodscape) and the corresponding effects on birth mass of fawns. Our study adds to a growing body of literature supporting a fundamental link between foodscape use and population performance of large herbivores. Wildlife managers can use the dynamic models we developed to assess habitat quality and to make quantitative predictions about how different management actions (e.g., forest thinning) are likely to influence habitat quality and performance of black‐tailed deer.

Adaptive, multi-paddock, rotational grazing management alters foraging behavior and spatial grazing distribution of free-ranging cattle

Sustainable management of grazinglands depends upon understanding how management practices influence livestock movements in space and time. We conducted a ranch-scale (2,600-ha) social-ecological experiment to examine how foraging behavior of cattle differs between a single large herd rotated adaptively among paddocks (collaborative, adaptive rangeland management; CARM) versus continuous, season-long grazing of paddocks by small non-rotational herds (traditional rangeland management; TRM). We analyzed how differences in cattle movement patterns may be linked to reductions in cattle growth rates and diet quality in the CARM treatment, relative to TRM. Cattle in the CARM treatment exhibited more linear grazing pathways, moved at lower velocity while grazing, and exhibited longer grazing bouts early in the growing season compared to TRM cattle. Grazing time within any given 10 × 10 m area was distributed more unevenly across TRM vs. CARM paddocks in years with average or above-average precipitation, but not in dry years. In all years, areas of high and low grazing intensity were more spatially clustered in TRM than CARM paddocks. Movement patterns of cattle managed using adaptive, multi-paddock rotations at high stock density (CARM) are consistent with less selective foraging. Such cattle form a “grazing front” that moves across the paddock and distributes grazing pressure in a more spatially homogeneous fashion. In years with substantial forage production, TRM cattle spent more time than CARM cattle in preferred areas of the paddock and foraged in more circular patches. In dry years, however, both treatments resulted in similarly even grazing distribution, likely due to limited intra-paddock variation in forage quality and quantity. At the ranch scale, these different intra-paddock movement patterns led to reductions in animal growth rates and no overall effect of grazing management on forage production.

Ranch-scale soil health, forage quality, and cattle grazing capacity linkages in a high-elevation steppe

The sustainability of rangeland grazing enterprises hinges on healthy and functioning soil resources. Yet information about how rangeland soil features influence livestock production has lagged relative to agronomic crop production. We established a ranch-scale assessment in Wyoming, USA to better understand soil health and livestock production. We integrated 26 years of animal day per hectare grazing records to relate livestock production to pasture-scale soil characteristics. In 2017, we measured 23 soil variables, and 11 forage variables (for Pascopyrum smithii) of 11 grazed pastures from 68 to 146 ha and three ungrazed exclosures. Pastures were stratified across animal day pasture categories (“Low,” “Medium,” “High,” and “None” or exclosure; considered a carrying capacity index). Significant relationships were found between nine of the 23 soil response variables but only one of the 11 forage response variables relative to the animal day pasture categories. Statistical analysis indicated significantly higher % soil organic carbon and forage lignin in the High animal day pasture category relative to the Low Animal Day pasture category (both p-values <0.05). No significant relationship was found between the Animal Day pasture category and forage crude protein (p = 0.3). The principal component analysis explained 98.22% (cumulative for the first two axes) of the variation of the soil health variables but was less insightful for forage quality variables (71.1% of variation explained). Soil organic carbon is a suitable indicator of animal days in pasture and may serve as a useful rangeland soil health indicator for livestock producers.

Assessment of Seasonal Variations in Forage Quality in Saanane Island National Park, Mwanza, Tanzania

Seasonal variations in proteins, vitamin A, vitamin C, carbohydrates and minerals (Ca, Fe, Na, K and P) for seven most grazed and four most browsed plant species were assessed using laboratory analysis to determine what nutrient resources were available to grazers and browsers inhabiting the Saanane Island. The results indicated great seasonal variations in proteins, vitamin A, vitamin C and carbohydrates which were statistically significant with P &lt; 0.01, F 3.444 at DF 5. Similarly, the minerals (Ca, Fe, Na, K and P) showed greater seasonal variations with K and P being higher during wet season, while Na and Fe were higher in dry season. The levels of proteins, vitamins, fibres and minerals were well above daily dietary requirements for grazers and browsers. These results suggested that both grazers and browsers were benefiting from seasonal differences in terms of available resources at disposal as animal health is regulated by levels of proteins and vitamins available in grazing and browsing materials. &#x0D; Keywords: Forage Quality, Minerals, Protein Saanane, Seasonality, Vitamin.

Responses of American black bears to spring resources

AbstractIn temperate regions of the world, food resources are seasonally limited, which causes some wildlife species to seek out nutrient‐rich resources to better meet their caloric needs. Animals that utilize high‐quality resources may reap fitness benefits as they prepare for mating, migration, or hibernation. American black bears (Ursus americanus) are omnivores that consume both plant and animal food resources to meet macronutrient needs. Black bears capitalize on high‐quality food resources, such as soft mast in summer and hard mast during autumn, but we know less about the importance of resource quality during spring. Therefore, we sought to understand the relationship between the spatiotemporal variation in the availability of food and resource selection of black bears during spring. We also aimed to infer potential changes in foraging tactics, from opportunistic foraging to more active selection. Although black bears are described as opportunistic omnivores, we hypothesized they select areas with high‐quality forage when available. We instrumented 7 black bears with GPS collars in 2017 and 2018 and estimated fine‐scale resource selection with integrated step‐selection functions. We found evidence that black bear movements were influenced by forage quality of vegetative food resources. However, we failed to find evidence that black bears actively alter their movements to take advantage of seasonal neonate elk. Although black bears represent a substantial cause of mortality for neonate elk, we found that black bears likely feed on neonates encountered opportunistically while traveling between patches of high‐quality forage. Few studies have shown evidence of an omnivorous species capitalizing on spatiotemporal variation in forage quality, yet our data suggest this may be an important strategy for species with diverse diets, particularly where resources are seasonally limited.

Effects of two water regimes on morphological traits, nutritive value and physiology of three Bituminaria bituminosa varieties from the Canary Islands

AbstractMorphological traits, nutritive values and physiological responses to two different water regimes of three Bituminaria bituminosa varieties: var. albomarginata, var. crassiuscula and var. bituminosa were evaluated in a greenhouse experiment. Two water regimes were imposed for 63 days; well‐watered (WW) plants and deficit‐watered (DW) plants, both starting from a high soil water content (dripping point). The three varieties showed similar aerial biomass reduction under reduced watering, 50% for var. albomarginata, 51% for var. bituminosa and 43% for var. crassiuscula. Var. Albomarginata showed lower shoot biomass under both water regimes than var. bituminosa (56.2% in WW plants and 55.2% in DW plants) and var. crassiuscula (52% in WW plants and 57.8% in DW plants). This lower shoot biomass could be attributed to the high initial soil water content imposed in this experiment, affecting early development. This hypothesis is supported by the lower root biomass production of var. albomarginata and its distribution. The DW treatment of this experiment was not sufficiently restrictive to cause morphological modifications, whilst of the forage quality variables analysed, only ash was affected. Var. crassiuscula and var. albomarginata had a lower specific leaf area (239 cm2 g‐1 and 235 cm2 g‐1, respectively) than var. bituminosa (352 cm2 g‐1), which might represent an important adaptation to high light intensity and temperature conditions. The values of stem mass fraction (SMF) and leaf mass fraction (LMF) for var. crassiuscula (SMF = 0.36 and LMF = 0.28) and var. albomarginata (SMF = 0.35 and LMF = 0.36) indicated better forage aptitude of these varieties than var. bituminosa (SMF = 0.50 and LMF = 0.19). All varieties showed good values of crude protein and digestibility, although important differences were found between leaf and stem. According to the studied morphological, nutritional and physiological traits, var. albomarginata showed the best aptitude for being introduced as permanent grasslands in some Mediterranean farming systems. However, the possible susceptibility of var. albomarginata to high water content in the soil could limit its introduction. These results help to inform the potential use of these three Canarian B. bituminosa varieties to improve Mediterranean rainfed grasslands of extensive farming systems.

Can Mowing Substitute for Fire in Semiarid Grassland?

Accumulating data indicate the importance of fire in rangeland systems. Mowing is a common management technique sometimes considered a surrogate for fire. However, direct comparisons of fire and mowing effects are limited. Our objective was to determine whether mowing can substitute for fire in rangeland by comparing effects on plant biomass, composition, cover, soil nutrients, and forage quality. Three disturbance treatments (nontreated control, spring mowing with clipping removal, and spring fire) were randomly assigned to 21 plots (5 × 5 m) each on silty and claypan ecological sites in a completely randomized design, with seven replications per site. Current-yr biomass was similar among control, mowed, and burned treatments (1 003, 974, 1 022 ± 64 kg ● ha−1). Mowing shifted functional group composition by reducing C3 perennial grass 12% and increasing forbs 8%. Non-native species were a larger component of mowed (12%) than control (6%) or burned plots (4%). Fire increased bare ground 35%, reduced litter 32%, and eliminated previous yrs’ growth the first growing season. Plant-available soil N and S more than doubled with fire, and there was a trend for more P in burned plots. Mowing effects were limited to a trend for less soil Fe. Mowing affected 42% of the forage quality variables with a 2% average improvement across all variables. Fire affected 84% of the variables, with a 12% average improvement. Mowing increased forage P and K, whereas fire increased forage concentrations of N, K, P, S, Mg, Fe, Mn, and Cu. Total digestible nutrients increased 1.1% with mowing and 2.1% with fire. In vitro dry matter disappearance increased 2.2% with mowing and 6.7% with fire. Burned plots had greater in vitro fermentation than controls or mowed plots. Although mowing can be a useful management tool, it is not a substitute for the ecological effects of rangeland fire.

Relationships between long-term fertilization management and forage nutritive value in grasslands

Effects of fertilization on grassland have been widely investigated in terms of botanical composition, forage yield and quality, and their agricultural and environmental consequences. However, there are no published studies of the contribution of fertilization to variability of forage quality involving systematic investigation of this effect. Therefore, our objectives were to: (i) evaluate the impact of long-term fertilization treatments on Arrhenatherion elatioris-type meadow vegetation, (ii) investigate effects of interaction among year, cut and fertilization on forage quality in association with forage yield and functional groups proportion with quantification of fertilization effect, and (iii) compare the predictive ability of visually estimated functional groups coverage (FGC) vs. weight proportion ratio of functional groups (FGW) for variability in forage quality in the first cut. Six mineral fertilization treatments (control, N0P40K100, and P40K100 in combination with 50, 100, 150 and 200 kg N ha−1) were evaluated over a three-year period (2014–2016) under a three-cut regime. Intensive NPK fertilization doubled forage yield and increased the grass proportion with a corresponding decrease of forbs and legumes. Grass proportion in harvested forage was positively correlated with fibre content in the first cut and with organic matter digestibility and net-energy for lactation in subsequent cuts. In all cuts there was a consistent correlation in ash and crude protein content with legumes and forbs. Fertilization had less influence on forage quality, compared with inter-year effects or seasonal variability. For each cut, fertilization contributed around 20% of the variability in forage quality, where half of its contribution was realized through increased yield and changes in proportion of functional groups. The explanation power of functional groups in the first cut was slightly higher for the FGC method than the FGW proportion method, which suggests both methods are at least as effective in relation to grassland nutritive value. In summary, if fertilization results in only small changes in grassland yield or botanical composition, its effect on forage quality is greatly reduced. Plant developmental stage or nutritive value of particular species are potential explanations for the rest of the variability.

CARACTERIZACIÓN DE LOS PASTIZALES DEL ÁREA DE PROTECCIÓN DE FLORA Y FAUNA NEVADO DE TOLUCA PARA LA PRODUCCIÓN OVINA

&lt;p&gt;In the Nevado de Toluca Flora and Fauna Protection Area (&lt;em&gt;Área de Protección de Flora y Fauna Nevado de Toluca&lt;/em&gt;—APFFNT), farmers engage in pastoral activity, using communal areas for grazing. This activity is a means of production that provides the necessary products for the subsistence of shepherds, although knowledge of the specific characteristics of the grasses and implications for livestock production is lacking. The objectives of this study were to evaluate the primary productivity, nutritional quality and predominant plant species of three grasslands in the APFFNT, in order to evaluate their Dry Matter (DM) production. Grasslands were selected in the Agua Blanca, Loma Alta and La Peñuela localities. In each locality six areas for study were defined, and in each of the area, an exclusion cage was placed. From September 2013 to August 2014, samples were taken every 28 days to determine the increase of the grass yield in each area over time. In the grasslands in Agua Blanca, significant differences were not observed in Net Forage Accumulation (NFA) across time. In the Loma Alta grasslands, however, production was different (P&amp;lt;0.05) from November to April, the months corresponding to the lowest production levels and the least precipitation. In the La Peñuela grasslands, the lowest NFA was produced in February and the highest NFA in July (P&amp;lt;0.05). The results presented in this paper indicate a high degree of variation in forage quality across the months studied. An increase in fiber and a decrease in protein was observed during the dry season. The results of this study provide an important foundation for sustainable development in livestock activity in the APFFNT grasslands.&lt;/p&gt;

Plastic adaptations of foraging strategies to variation in forage quality in Alpine chamois (Rupicapra rupicapra)

Foraging efficiency strongly affects individual fitness and is influenced by diverse factors such as food quality and quantity, as well as intra- and inter-specific interactions. We investigated whether Alpine chamois (Rupicapra rupicapra (Linnaeus, 1758)) in a protected area in the Swiss Alps adapted their foraging behaviour to forage availability and quality by modeling the bite and step rates of individuals on vegetation nitrogen content, relative plant cover, sex, daytime, air temperature, and slope. Vegetation characteristics were derived using remote sensing data from airborne imaging spectroscopy data sets and feeding locations determined using a theodolite. Chamois increased their bite rates with decreasing forage nitrogen content, decreasing slope, and increasing temperature. Step rates were higher at high temperatures and decreased with increasing relative plant cover. Males showed higher bite rates and lower step rates than females. Daytime had no influence on either bite or step rates. An increase in bite rate may represent a plastic adaptation of foraging behaviour to compensate for lower nutritional quality of the available vegetation. Our results show variability in foraging behaviour according to both vegetation characteristics and physical environment and emphasize the use of remote sensing data to investigate relationships between habitat and subtle behavioural adaptations in ungulates.

Forage production from fine branches and sprouts of native maniçoba

The growth and forage production of Manihot glaziovii were evaluated in plants growing in Itapetim-PE, Brazil via a complete block experimental design with four treatments (0, 33, 50, and 100% branch cutting intensity) to analyze increases in height and diameter. Furthermore, 3×2 factorial treatments (three branch cutting intensities: 33, 50, and 100% as well as two types of collected forage material: Branches with diameter &lt; 10 mm and corresponding sprouts on the same branches 1 year after being cut) were analyzed for improvement in forage quantity and quality parameters. Height increase was affected (P &lt; 0.05) by branch cutting intensity (0.29, 0.11, 0.43, and -0.04 m plant-1, respectively, for 0, 33, 50, and 100% branch cutting intensities), while the increase in diameter was not affected (P &gt; 0.05) (3.97 mm plant-1 was the overall mean increase). Cutting intensity×type of collected material, in combination, affected (P &lt; 0.05) the quantity of the collected forage: means were considered similar (P &gt; 0.05) in the first (branches) and second (sprouts) forage collection events for 33% (0.66 and 0.75 kg dry matter plant-1, respectively) and 50% (1.40 and 1.73 kg dry matter plant-1, respectively) cutting intensities; it decreased (P &lt; 0.05) from the first to the second collection events, when 100% of branches and sprouts were harvested (3.37 and 2.06 kg dry matter plant-1, respectively). The combined effects of aforementioned parameters were observed (P &lt; 0.05) as interactions for some forage quality variables. Neutral detergent fiber content remained constant (P &gt; 0.05) between 50.57 and 54.41% in forage containing branch and sprouts from 33 and 50% cutting intensities. It increased (P &lt; 0.05) to 62.20% in sprouts from 100% cutting intensity. Acid detergent fiber content increased (P &lt; 0.05) from around 38.4% to 46.63% in sprouts from plants subjected to 100% cutting intensity. The crude protein (between 8.72 and 10.08%) and ether extract (between 2.74 and 4.35%) contents were unaffected (P &gt; 0.05) by these factors. Mineral matter content was higher (P &lt; 0.05) in sprouts from all cutting intensities with 5.9% being the highest. Up to 50% of Manihot glaziovii branches with Ø &lt; 10 mm and corresponding 1-year-old sprouts can be pruned with no negative effect on the quality and quantity (up to 1.73 kg dry matter plant-1) of the collected forage.

Fine-scale spatial and seasonal rangeland use by cattle in a foot-and-mouth disease control zones

Overgrazing of ranglands and foot-and-mouth disease (FMD) are persistent problems in the communal lands bordering the Kruger National Park (KNP) and the adjacent private game reserves in South Africa. Improved livestock management is needed to address these problems, and detailed understanding of cattle ranging behaviour in the FMD control zones is central to improving livestock management. We used environmental data on seasonal variation in forage quality (nitrogen content) and quantity (biomass) derived from high resolution satellite imagery, coupled with cattle GPS locations, to develop a resource utilization function of cattle space use patterns and predicted spatial patterns of their probability of occurrence in the wet and dry seasons. We calculated cattle resource utilization distributions and delineated home ranges of cattle from six villages by applying utilization kernels using the plug-in method as a bandwidth estimator. The overlap between seasonal home ranges was 61% and between core areas 49%, indicating seasonal selectivity mainly within the home ranges. Cattle selected forage with higher quantity and quality during the dry season but behaved like bulk grazers in the wet season. Furthermore, we found that herds in the dry season usually have smaller home ranges and stay closer to water sources and villages than in the wet season. Our prediction maps highlight seasonal differences in probability of cattle occurrence, with implications for rangelands management strategies to minimalize overgrazing and FMD transmission.

Determination of fibre and protein content in heterogeneous pastures using field spectroscopy and ultrasonic sward height measurements

Feeding of livestock on pastures requires constant monitoring of diet composition to ensure consistent levels of animal production. The widely used but conventional techniques to measure the components of feed are impractical to obtain in-field forage quality status for making real-time decisions. Assessment of forage quality parameters using proximal sensing is of particular interest. The present study aimed to demonstrate the potential of using a combination of ultrasonic and canopy reflectance data to predict forage quality variables of heterogeneous pastures. A field experiment with pastures continuously grazed by cows with three stocking density treatments (moderate, lenient and very lenient stocking) was used to calibrate ultrasonic and hyperspectral reflectance sensors. Hyperspectral analysis by a modified partial least square regression (MPLSR) resulted in maximum accuracy for the prediction of acid detergent fibre (ADF) and crude protein (CP) (R2calibration=0.63–0.85). Any reduction of hyperspectral data into vegetation indices based on few specific narrow wavebands or satellite broadbands reduced prediction accuracy significantly. However, prediction of ADF and CP was improved by a combined analysis of ultrasonic sward height and vegetation indices or satellite broadbands, so that most calibration models exceeded an RPD (ratio of standard deviation and standard error of prediction) value of 1.4, which is considered as an acceptable predicting capability for variable field condition. Our findings showed that combined sensing systems using reflectance and ultrasonic sensors may provide acceptable prediction accuracies for practical application even under extremely heterogeneous pasture conditions.

Nutritional, technological and managerial parameters for precision feeding to enhance feed nutrient utilization and productivity in different dairy cattle production systems.

Abstract Increased future demand of animal products as well as competition between food, feed and fuel, require efficient utilization of feed resources to strengthen environmental, economic and social sustainability of livestock systems. The objective of this review is to summarize current knowledge on precision feeding (PF) and the relevance of PF approaches in dairy cattle production systems in developing countries. The concept of PF aims at achieving balanced nutrition (matching animal requirements with nutrient supply, preferably from locally available feed resources) to improve animal productivity and to reduce both the cost of production and environmental pollution. In addition to the supply of proper amounts of nutrients to the dairy cow using various methodologies and tools, approaches that enhance overall nutrient digestion and availability to the animal are also discussed as an integral part of PF. These approaches involve improved analyses of feed ingredients, nutrient requirement determination, formulation of a balanced ration, individual feeding, optimization of rumen and post rumen digestion, and optimization of metabolism of absorbed amino acids and other nutrients. Based on identified and analysed PF approaches, processing and treatment of forage, including conservation through ensiling, is promising to improve feed intake and productivity of the cow and to reduce excretion of environmental pollutants per unit milk. Experiments with rumen protected nutrients for both fat and protein gave a wide range of results. Inconsistent effects of the use of enzymes such as cellulases and xylanases on feed efficiency have been observed. Plant extracts need more research to get tangible results but have a broad scale of potential (indirect) advantages on production and health. Similarly more research is needed for probiotics and acidifiers, which have shown inconsistent results. Medicinal or hormonal approaches have proven to be effective in animal performance and feed efficiency. Feeding concepts, such as ration balancing programmes or the use of feed blocks, resulted in improved feed efficiency and substantially increased farmer income. In view of large variation in forage quality, rapid determination of nutrient composition of forage on site is indispensable in PF of dairy cattle. The relevance of application of the elaborate approaches for intensive, mixed crop-livestock, mixed extensive and extensive systems have been discussed. The focus of PF in developing countries should be on using feed resources that do not compete with human food, and in amounts that meet the nutrient requirements for production from the targeted animal. Policy and institutional building options are needed to realize the potential of PF for sustainable dairy production systems.

Influence of management regime and harvest date on the forage quality of rangelands plants: the importance of dry matter content.

In spite of their recognized ecological value, relatively little is known about the nutritional value of species-rich rangelands for herbivores. We investigated the sources of variation in dry matter digestibility (DMD), neutral detergent fibre content (NDF) and nitrogen concentration (NC) in plants from species-rich Mediterranean rangelands in southern France, and tested whether the dry matter content (DMC) was a good predictor of the forage quality of different plant parts. Sixteen plant species with contrasting growth forms (rosette, tussock, extensive and stemmed-herb) were studied, representative of two management regimes imposed in these rangelands: (i) fertilization and intensive grazing and (ii) non-fertilization and moderate grazing. Among the 16 plant species, four species were found in both treatments, allowing us to assess the intraspecific variability in forage quality and DMC across the treatments. The components of nutritional value (DMD, NDF and NC) as well as the DMC of leaves, stems and reproductive plant parts, were assessed at the beginning of the growing season and at peak standing biomass. All components of nutritional value and DMC were affected by species growth form: rosettes had higher DMD and NC than tussocks; the reverse being found for NDF and DMC. As the season progressed, DMD and NC of the different plant parts decreased while NDF and DMC increased for all species. DMC was negatively related to DMD and NC and positively to NDF, regardless of the source of variation (species, harvest date, management regime or plant part). Path analysis indicated that NDF was the main determinant of DMD. Better assessment of forage quality in species-rich systems requires consideration of their growth form composition. DMC of all plant parts, which is closely related to NDF, emerged as a good predictor and easily measured trait to estimate DMD in these species-rich systems.

Relationships between botanical composition, yield and forage quality of permanent grasslands over the first growth cycle

AbstractThis study examined the relationships between botanical composition and forage parameters (yield and forage quality variables) in 153 permanent grasslands located in the Massif Central of France. Grasslands were sampled at two vegetation stages in the first growth cycle. Botanical composition, yield, ash, crude protein, neutral detergent fibre, acid detergent fibre, acid detergent lignin, organic matter digestibility (OMD) and voluntary intake (VI) were estimated for each sample. Temporal variability in species–forage parameter relationships were accounted for using innovative multivariate analyses applied mainly in ecological science. Crude protein and OMD were weakly correlated when each harvest time was analysed separately. Species–forage parameter relationships remained stable during the first growth cycle. The stability of these relationships indicates that permanent grasslands dominated by competitive species were associated with high yield and forage quality values whereas permanent grasslands composed of conservative species and/or high proportions of senescent material were associated with high structural carbohydrate values and low yield, OMD and VI values. Based on these relationships, we propose a typology of permanent grasslands along with a set of indicator species enabling non‐specialist botanists to easily classify grasslands for grassland management purposes.

Bison foraging responds to fire frequency in nutritionally heterogeneous grassland

Foraging decisions by native grazers in fire‐dependent landscapes modulate the fire–grazing interaction. Uncovering the behavioral mechanisms associated with the attraction of grazers to recently burned areas requires understanding at multiple spatial scales in the ecological foraging hierarchy. This study focused on feeding in the area between steps in a foraging bout, the feeding station, as forage chemistry and vegetation architecture play central roles in these fine‐scale, feeding‐station decisions. The forage maturation hypothesis (FMH) uses the temporal dynamics of forage quality and quantity in grasslands to explain the distribution of large herbivores, but does not address herbivore responses to inter‐patch variation caused by fire‐induced nutrient increases of forage quality. Using an experimental setting with contrasting fire treatments we describe the effects of variable burn history on foraging kinetics by bison at Konza Prairie Biological Station (KPBS). We assessed the potential to link the FMH in a complementary fashion to the transient maxima hypothesis (TMH) to explain temporal variation in bison responses to grassland forage quality and quantity in response to burning at different temporal frequencies. Forage attributes met predictions of the TMH that allowed us to investigate how forage maturation affects feeding station foraging behavior across watersheds with varying burn frequency. At sites burned in the spring after several years without burning, both bite mass and intake rate increased with increasing biomass at a greater rate during the growing season than during the transitional midsummer seasonal period. In these infrequently burned watersheds, early growing season bite mass (0.6 ± 0.05 g; mean ± SE), bite rate (38 ± 1.5 bites/min), and intake rate (21 ± 2.3 g/min) was reduced by ~15%, 13%, and 29% during the midsummer transitional period. A behavioral response in foraging kinetics at the feeding station occurred where a nonequilibrial pulse of high‐quality resource was made available and then retained by repeated grazing over the growing season. Our results provide the first experimental evidence for demonstrating the fine‐scale behavioral response of a large grazer to fire‐induced changes in forage attributes, while linking two prominent hypotheses proposed to explain spatial variation in forage quality and quantity at local and landscape scales.

Modelling methane emissions from remotely collected liveweight data and faecal near-infrared spectroscopy in beef cattle

The objective of the present study was to develop a model-data fusion approach using remotely collected liveweight (LW) data from individual animals (weighing station placed at the water trough) and evaluate the potential for these data from frequent weighing to increase the accuracy of estimates of methane emissions from beef cattle grazing tropical pastures. Remotely collected LW data were used to calculate daily LW change (LWC), i.e. growth rate on a daily basis, and then to predict feed intake throughout a 342-day grazing period. Feed intake and diet dry matter digestibility (DMD) from faecal near-infrared spectroscopy analysis were used to predict methane emissions using methods for both tropical and temperate cattle as used in the Australian national inventory (Commonwealth of Australia 2014). The remote weighing system captured both short- and long-term environmental (e.g. dry and wet season, and rainfall events) and management effects on LW changes, which were then reflected in estimated feed intake and methane emissions. Large variations in all variables, measured and predicted, were found both across animals and throughout the year. Methane predictions using the official national inventory model for tropical cattle resulted in 20% higher emissions than those for temperate cattle. Predicted methane emissions based on a simulation using only initial and final LW and assuming a linear change in LW between these two points were 7.5% and 5.8% lower than those using daily information on LW from the remote weighing stations for tropical and temperate cattle, respectively. Methane emissions and feed intake can be predicted from remotely collected LW data in near real-time on a daily basis to account for short- and long-term variations in forage quality and intake. This approach has the potential to provide accurate estimates of methane emissions at the individual animal level, making the approach suitable for grazing livestock enterprises wishing to participate in carbon markets and accounting schemes.

Effects of short-term variation in forage quality and forage to concentrate ratio on lactating dairy cows

Within-farm variation in forage composition can be substantial and potentially costly, and it presents challenges for sampling the forage accurately. We hypothesized that day-to-day variation in forage neutral detergent fiber (FNDF) concentrations and diet variation caused by sampling error would have negative effects on production measures in lactating dairy cows. Twenty-four Holstein cows (73d in milk) were used in 8 replicated 3×3 Latin squares with 21-d periods. Treatments were (1) control (CON), (2) variable (VAR), and (3) overreacting (ORR). On average, over the 21-d period, all 3 treatments were the same [24.7% FNDF and 48.2% forage dry matter (DM) composed of 67% alfalfa silage and 33% grass silage]. The CON treatment was essentially consistent day-to-day in total forage and FNDF concentrations and proportion of alfalfa and grass silages. The VAR treatment changed daily (in a random pattern) in proportion of alfalfa and grass silages fed, which resulted in day-to-day changes in FNDF (range was 21.5 to 28%). The ORR treatment varied in a 5-d cyclic pattern in total forage and FNDF concentrations (26, 24, 28, and 21.5% FNDF). Over the 21d, ORR (25.1kg/d) had higher DM intake compared with CON (24.5kg/d) and VAR (24.3kg/d). Milk production (42.8kg/d), milk fat (3.5%), and milk protein (2.8%) were not affected by treatment; however, a treatment × day interaction was observed for milk production. Lower daily milk yields for VAR and ORR compared with CON were rare; they only followed sustained 4- and 5-d periods of feeding higher FNDF diets compared with CON. In contrast, increased daily milk yields for VAR and ORR versus CON were more frequent and followed sustained diet changes of only 2 or 3d. Lipolytic and lipogenic-related enzyme mRNA abundances in subcutaneous adipose tissue were not affected by treatment. Treatment × day interactions were observed for milk fatty acid markers of cellulolytic bacteria (iso-14:0, iso-15:0, iso-16:0) and lipolysis (18:0) and generally followed the expected response to changes in daily rations. Overall, extreme daily fluctuations in FNDF had no cumulative negative effect on production measures over a 21-d period, and daily responses to transient increases in FNDF were less than expected.