Pasture Feeding Research Articles

Recent investigations of ergot alkaloids incorporated into plant and/or animal systems.

Recent investigations of ergot alkaloids incorporated into plant and/or animal systems.

Pasture harvest, carbon sequestration and feeding potentials under different grazing intensities

Pasture harvest, carbon sequestration and feeding potentials under different grazing intensities

Varying pasture growth and commodity prices change the value of traits in sheep breeding objectives

Breeding programs for livestock require economic weights for traits that reflect the most profitable animal in a given production system. Economic weights are commonly based on average conditions. In pasture based livestock production systems the cost of feed is an important profit driver, but availability of feed from pasture can vary greatly within and between years. Additionally, the price of supplementary feed during periods of feed shortage and the prices for meat and wool vary between years. Varying prices and pasture growth can change the optimal management of the flock affecting profitability. This paper investigates how variation in commodity prices and pasture growth affect the economic values of traits in the breeding objective. We modelled a sheep farm with a self-replacing Merino flock bred for wool and meat in a Mediterranean environment. We optimised management decisions across 5years using dynamic recursive analysis to maximise profit when commodity prices and pasture growth varied annually. Actual pasture growth and wool, meat, and grain prices from 2005 to 2009 were used. Management could adapt to varying pasture growth and commodity prices by changing sheep numbers, age structure of the flock and amount of grain fed to sheep. The economic value of seven traits in the breeding objective were compared for a scenario with average pasture growth and commodity prices over years and a scenario with varying pasture growth and commodity prices over years. Variation in pasture growth and commodity prices decreased average profit and increased the economic value of all breeding goal traits compared to the average scenario. The order of importance of traits stayed the same between varying and average scenarios but the relative importance of traits changed. The economic values that increased the most were for traits that had increased profit with the smallest impact on energy requirements such as yearling live weight, longevity and fibre diameter. Our results showed that it is important to account for variation in feed availability and commodity prices when determining the expected profit and economic values for traits. The results also suggest that whereas variation in pasture growth and commodity prices between years makes the farming operations less profitable, these changing conditions increase the genetic variation in profitability of sheep. Therefore, genetic improvement has more value relative to scenarios where pasture feed supply and prices are constant.

Cheddar Cheese from Cow Milk with Elevated Conjugated Linoleic Acid Levels

The aim of the study was to evaluate the effect of feed management on conjugated linoleic acid (CLA) level in milk and subsequently on fatty acid profile of cheese. Twenty cows were divided into 2 groups, fed on grass silage and pasture feed with sunflower supplementation for 14 days. Milk samples were collected and analyzed for composition and fatty acid profile using gas chromatograph. Cheddar cheese was manufactured from both milk types and ripened for 120 days. During ripening, it was analyzed for composition and fatty acid quantification. The supplemented diet significantly increased the CLA content in milk. Similarly the cis-9, trans-11 CLA content in Cheddar cheese were more than twofold in case of supplemented diet as compared to grass silage. During ripening, CLA concentration remained stable. The sunflower supplementation showed no effect on cheese composition. Hence, supplemented pasture resulted in elevated CLA content in milk compared to grass silage.

Effects of dam size and nutrition during pregnancy on lifetime performance of female offspring

It has previously been shown that both dam size and nutrition in pregnancy can affect individual performance traits of ewe offspring to three years of age. The objective of this study was to determine if dam size and nutrition during pregnancy affected lifetime productivity to six years of age in ewe offspring. In 2005, Romney ewes (G0) were selected as heavy (H; n=450, mean live weight=60.8±0.18kg (s.e)) or light (L; n=450; mean live weight=42.5±0.17kg) based upon live weight at the time of mating, and then randomly allocated to receive pregnancy maintenance (M) or ad libitum (A) pasture feeding treatment from day 21 to 140 of pregnancy; resulting in four treatment groups (HA, HM, LA and LM). Live weight, body condition and reproductive performance data were recorded in the ewe offspring (HA n=55, HM n=58, LA n=42 and LM n=43) from 2007 to 2011 (580–2298 days of age). In addition live weights of their lambs (grand progeny) to weaning were recorded (n=1491 in total). Daughter live weights and body condition scores were inconsistently affected by dam size and nutrition over time and at most measurement points no differences (P>0.05) were found. At 2050 days of age A-daughters had higher proportion that ovulated than M-daughters (P=0.01) and A-daughters gave birth to more lambs than M-daughters (P=0.05), but there were no differences (P>0.05) found in relation to number or weight of lambs weaned. Daughters from H dams had a higher total number of antral follicles (P=0.018) and total number of follicles (P=0.05) at 2599 days of age, and greater proportion (P=0.016) of daughters that were present (survived) in the flock in 2011 compared to daughters from L dams. There were no interactions (P>0.05) between dam size and nutrition for any parameters of lifetime reproductive performance data collected. This study suggests that dam size and nutrition during pregnancy has a minimal impact on daughter lifetime performance. Therefore under the conditions of the present study farmers do not need to consider dam size and pregnancy nutrition when selecting progeny as replacement ewes.

Fatty acid profile of zebu beef cattle from the Central African sub-region

This study analysed the meat fatty acid (FA) composition of three zebu breeds, Gudali (GU), White Fulani (WF) and Red Mbororo (RM), raised on savannah pasture and monitored in the commercial context of the Yaounde abattoir. Samples of m. longissimus thoracis from 60 bulls belonging to the GU, WF and RM breeds were collected and analysed for fat and FA composition. The fat content of the meat was low, but similar across breeds (1.34 ± 0.912 g/100 g muscle, mean ± SD). Meat from the GU breed had higher C18:3n-3 and C22:5n-3 proportions and lower C18:0 and total saturated FA proportions than WF meat. Red Mbororo meat had an intermediate FA composition compared with the other breeds. The elongase and Δ9 desaturase indices were comparable among breeds. In summary, the results indicate that there are minimal differences in beef FA composition of the three breeds from the Central African sub-region. Additionally, based on the polyunsaturated FA (PUFA) proportion, 13.9% of the total lipids and n-6/n-3 PUFA ratio, 1.95, consumption of beef from these breeds could be beneficial to human health. This is possibly owing to the pasture feeding and low fat content of the beef. Keywords : Intramuscular fat; fatty acid composition; natural pasture

Regional Management of Farmland Feeding Geese Using an Ecological Prioritization Tool

Wild geese foraging on farmland cause increasing conflicts with agricultural interests, calling for a strategic approach to mitigation. In central Norway, conflicts between farmers and spring-staging pink-footed geese feeding on pastures have escalated. To alleviate the conflict, a scheme by which farmers are subsidized to allow geese to forage undisturbed was introduced. To guide allocation of subsidies, an ecological-based ranking of fields at a regional level was recommended and applied. Here we evaluate the scheme. On average, 40 % of subsidized fields were in the top 5 % of the ranking, and 80 % were within the top 20 %. Goose grazing pressure on subsidized pastures was 13 times higher compared to a stratified random selection of non-subsidized pastures, capturing 67 % of the pasture feeding geese despite that subsidized fields only comprised 13 % of the grassland area. Close dialogue between scientists and managers is regarded as a key to the success of the scheme.

Fatty acid and sensory profiles of Caciocavallo cheese as affected by management system

The effect of season of the year associated with changes in feeding and management system (pasture-based vs. confinement) on milk and cheese fatty acid profile and on sensory properties of Caciocavallo cheese was evaluated on 3 mountain dairy farms. Each farm used a pasture-based feeding system from April to June and from September to October (PS), and a confinement system for the rest of the year (CS). As a consequence of grazing, PS milk showed higher percentages of C18:3, cis-9,trans-11 conjugated linoleic acid, and trans-11 C18:1, and a reduced percentage of C16:0. The fatty acid profile of cheese largely reflected that of the corresponding raw milk from which cheese was made. This led to a significant decrease of atherogenic index in cheeses produced from cows on pasture. Based on sensory analysis, cheese from animals kept on pasture was more yellow and had a lower intensity of butter and smoked odors than did CS cheese. In addition, grazing induced a lower intensity of bitter and a higher intensity of spicy flavors compared with cheese from CS animals. In regard to texture, pasture feeding resulted in higher intensity of friability and graininess. All cheeses performed well in consumer tests; the panel found all samples more than acceptable for overall liking, and for liking according to appearance, taste/flavor, and texture. Overall liking of Caciocavallo cheese, as assessed by slope analysis, was affected primarily by taste/flavor (raw slope k=0.88) and texture (k=0.97), whereas appearance had a lesser effect (k=0.72). The acidic and sensory profiles of cheese were well discriminated, with healthier cheeses produced by grazing cows. Therefore, wider use of pasture should be promoted to accentuate this favorable feature. Based on the specific nutritional and sensory characteristics of mountain Caciocavallo cheese, particularly that obtained from grazing animals, efforts should be made to indicate the quality of this cheese to the consumer and improve product recognition.

Influence of trough versus pasture feeding on average daily gain and carcass characteristics in ruminants: A meta-analysis

Quantitative meta-analysis was run on 108 publications featuring 116 experiments and 399 treatments dealing with the effect of trough or pasture feeding environment (FE) on ruminant performances. The objective was to compare the effect of trough or pasture FE on ADG, diet OM digestibility (OMD), various carcass characteristics, and the interaction between FE and complementation modalities. Live weight was adjusted to compare results between species. Results showed that trough-fed animals had higher ADG (+17.89%; P < 0.001), hot carcass yield (HYield; + 2.47%; P < 0.001) and carcass fat content (+ 24.87%; P < 0.001) than pasture-fed animals but lower carcass muscle and bone percentages (-1.60% [P = 0.010] and -7.63% [P = 0.003], respectively). Feeding environment had no effect on diet OMD (P = 0.818), but the number of observations was low. After considering the addition or not of concentrate in the diet (addiCO), FE effect persisted on ADG (P = 0.024) and carcass fat content (P = 0.027) but not on HYield (P = 0.078) or muscle and bone percentages (P = 0.119 and P = 0.581, respectively). After considering the nature of the concentrate (natCO), FE effect persisted on ADG (P < 0.001) and HYield (P = 0.004). Considering the percentage of concentrate in the diet (PCO) erased FE effect on ADG (P = 0.891) and HYield (P = 0.128). In contrast, considering the quantity of concentrate(QCO) erased FE effect on ADG (P = 0.084) but not on HYield (P = 0.006) or on carcass fat and muscle contents (P = 0.040 and P = 0.040, respectively) although the FE effect on carcass bone content persisted (P = 0.550). Animal species and physiological stage had no effect on any of the variables studied (P > 0.05) but experiment did (P ≤ 0.001). The increase in ADG was positively correlated to HYield in cattle (P = 0.002) and small ruminants (P = 0.003) and positively linked to carcass fat content (P = 0.007) but not carcass muscle content, which actually decreased (P = 0.001). Overall, this meta-analysis confirmed previous reports of FE effects and revealed how the differences generally reported result from a confounding effect of FE and nature of the diet. Indeed, in most of the studies used, trough-fed animals were supplemented with concentrate whereas pasture-fed animals were not. This research also highlighted the fact that pasture-fed animals have the potential to achieve the same performances as trough-fed animals when fed a similar diet.

Oxidative stability of milk fat in respect to its chemical composition

The oxidative stability of milk fat from non-pasteurised sweet cream was examined over a 24-month period with respect to the fatty acid composition, and β-carotene, vitamin A, α-tocopherol and phospholipid contents. The oxidative stability of milk fat was significantly higher during the period of pasture feeding of cows compared with the stall feeding period. Positive correlations were reported between the oxidative stability index and contents of fat-soluble vitamins and phospholipids in milk fat. An equation developed from a multiple regression analysis with step-wise elimination of variables indicated that the oxidative stability of milk fat was affected to the greatest extent by the contents of α-tocopherol, β-carotene, C18:1 cis and trans acids and conjugated linoleic acid.

The effect of production system and management practices on the quality of meat products from ruminant livestock

Demands for products of animal origin are increasing worldwide owing to the significant growth in the human population and changes in the health, wealth and life expectancy of people. The agricultural sector has the scientific knowledge, expertise and technology to respond to these challenges, but consumers are concerned about the methods used to meet these new challenges. They are also concerned about the environmental impact of modern technologies and intensification of production systems. Various combinations of pasture-based and intensive systems are employed to raise ruminant livestock, depending on resources and climate. The quality of animal products from production systems differs, but there are advantages and disadvantages for each. In South Africa, cattle and sheep are generally fattened for short periods to ensure efficient production and to meet market requirements. This is more easily achieved by feeding different proportions of concentrate diets, with or without feed additives and growth promotants that are approved for use in food-producing animals. Hormonal growth implants are strictly regulated for use in animal production systems. Production systems affect both the extrinsic and intrinsic aspects of carcass and meat quality of livestock. Extrinsic aspects that are affected include weight gain, age at slaughter and carcass weight. Concentrate feeding generally yields a more consistent carcass composition than pasture-fed animals, which addresses the necessity for more consistent meat quality. Intrinsic aspects of animal products that are affected include carcass composition and conformation, carcass fat content and colour, meat composition, colour, tenderness and flavour. Beef and lamb from pastures are darker, and carcass fat contains more yellow pigments, which may affect a consumer’s choice to purchase. The typical pasture flavour in meat is because of the presence of branched-chain fatty acids, 3-methylindole and other oxidation products, and off-flavours are often detected. In many countries, the meat flavour of intensively fed livestock is preferred to pasture-fed animals, but certain consumers prefer the more intense pasture flavour. Pasture feeding has beneficial effects on n-3 fatty acids, notably eicosapentaenoic acid (EPA, C20:5n-3) and docasahexaenoic acid (DHA, C22:6n-3). Beef and lamb from pasture-fed animals are generally less tender, but shelf life is better, owing to the presence of antioxidants such as vitamin E.Keywords: Hormonal growth implants, feed additives, antimicrobial implants, carcass quality, meat quality

Improving beef meat colour scores at carcass grading

Unacceptable meat colour scores at the time of carcass grading are associated with reduced meat quality and consumer rejection. We hypothesised that the meat colour at carcass grading would be influenced by the pH and temperature decline post slaughter, as these would be determined by animal and processing factors. Beef carcasses (n = 1512) at seven Australian processing plants were assessed, at grading, for the meat colour of the M. longissimus thoracis. Statistical modelling determined the animal, carcass and processing factors contributing to the meat colour score at carcass grading. The occurrence of unacceptably dark meat dropped from 8 to 3% when the time of grading was increased from 14 to 31 h post slaughter (P &lt; 0.01). A high temperature at pH 6 (rigor temperature), high final pH (pHF), pasture feeding and older animals were associated with dark M. longissimus thoracis at carcass grading (P &lt; 0.05 for all). Less than 30% of carcasses with non-compliant pHF displayed a dark non-compliant meat colour &gt;3, indicative of an opportunity to determine the mechanism behind this pH-induced colour development and thus reduce the incidence of non-compliance. It is recommended that when there is a high occurrence of carcasses with a dark meat colour &gt;3 that the time from slaughter to grading is checked to ensure carcasses are in full rigor at the grading point. This will assist in minimising economic penalties due to dark-coloured carcasses. Finally, animal factors, such as maturity and feeding regime also had a considerable impact on the meat colour at carcass grading.

Interaction between plant physiology and pasture feeding value: a review

Plant–animal interactions impact on all elements of pasture and animal performance in grazing systems. The quality of pastures for animals can be described in terms of feeding value (FV), which is a combination of feed nutritive value (NV) and voluntary intake. There are numerous complex interactions between plant physiology and pasture FV and NV. This review focuses on these interactions in four key areas (plant growth strategies, phenological development, pasture regrowth, and response to environmental stress), extracting key principles and illustrating how plant breeding or management may be used to manipulate such interactions to improve FV. The FV is low in pastures with native species that have evolved in nutrient-poor environments, especially if there are greater proportions of C4 than C3 species in the sward. Reproductive development of grasses and long grazing intervals (which affect stage of regrowth) reduce the proportion of leaf and increase stem or dead matter content in the sward. This is exacerbated by environmental stresses such as warmer temperatures and water deficit. Management decisions provide a means of manipulating many of these interactions to improve the FV of pasture, especially by improving soil nutrient status, using irrigation where possible, introducing exotic perennial pasture species such as perennial ryegrass, phalaris and tall fescue, linking the timing of grazing to stage of regrowth, and carefully managing post-grazing residual sward state. Likewise, plant breeding has focused on altering the flowering date of grasses, reducing aftermath heading, and reducing lignification within the plant to improve the FV of pasture for livestock.

Influence of trough versus pasture feeding on average daily gain and carcass characteristics in ruminants: A meta-analysis

Influence of trough versus pasture feeding on average daily gain and carcass characteristics in ruminants: A meta-analysis

Predicting Levels of Crude Protein, Digestibility, Lignin and Cellulose in Temperate Pastures Using Hyperspectral Image Data

Hyperspectral sensors provide the potential for direct estimation of pasture feed quality attributes. However, remote sensing retrieval of digestibility and fibre (lignin and cellulose) content of vegetation has proven to be challenging since tissue optical properties may not be propagated to the canopy level in mixed cover types. In this study, partial least squares regression on spectra from HyMap and Hyperion imagery were used to construct predictive models for estimation of crude protein, digestibility, lignin and cellulose concentration in temperate pastures. HyMap and Hyperion imagery and field spectra were collected over four pasture sites in southern Victoria, Australia. Co-incident field samples were analyzed with wet chemistry methods for crude protein, lignin and cellulose concentration, and digestibility was calculated from fiber determinations. Spectral data were subset based on sites and time of year of collection. Reflectance spectra were extracted from the hyperspectral imagery and collated for analysis. Six different transformations including derivatives and continuum removal were applied to the spectra to enhance absorption features sensitive to the quality attributes. The transformed reflectance spectra were then subjected to partial least squares regression, with full cross-validation “leave-one-out” technique, against the quality attributes to assess effects of the spectral transformations and post-atmospheric smoothing techniques to construct predictive models. Model performance between spectrometers, subsets and attributes were assessed using a coefficient of variation (CV), —the interquantile (IQ) range of the attribute values divided by the root mean square error of prediction (RMSEP) from the models. The predictive models with the highest CVs were obtained for digestibility for all spectra types, with HyMap the highest. However, models with slightly lower CVs were obtained for crude protein, lignin and cellulose. The spectral regions for diagnostic wavelengths fell within the chlorophyll well, red edge, and 2000-2300 nm ligno-cellulose-protein regions, with some wavelengths selected between the 1600 and 1800 nm region sensitive to nitrogen, protein, lignin and cellulose. The digestibility models with the highest CV’s had confidence intervals corresponding to ±5% digestibility, which constitutes approximately 30% of the measured range. The cellulose and lignin models with the highest CV’s also had similar confidence intervals but the slopes of the prediction lines were substantially less than 1:1 indicating reduced sensitivity. The predictive relationships established here could be applied to categorizing pasture quality into range classes and to determine whether pastures are above or below for example threshold values for livestock productivity benchmarks.

Pertumbuhan dan Hasil Tiga Varietas Alfalfa (Medicago sativa L.) dengan Perlakuan Tiga Macam Rhizobium pada Media Tanam Regosol Asal Banguntapan

ABSTRACT Different alfalfa varieties type of Rhizobium (a side of Rhizobium meliloti) affect to root nodule formation that will have an influence on the growth and yield quality of alfalfa. The rare presence of Rhizobium meliloti so it need to look for other potential rhizobium expected to form root nodules of alfalfa. The purpose of this research is to study the interaction of the three varieties of alfalfa inoculated with different type of rhizobium on growth and quality of alfalfa yield of the first cut. The experiment was conducted using a completely randomized design with factorial experiment in March to June 2012 in the Green House Laboratory of Forage and Pasture Feed Faculty of Animal Husbandry Gadjah Mada University. Data measurements and observations were done on growth parameters and the quality of the results and were analyzed by analysis of variance with a completely randomized design, and followed by Duncan's multiple range test level 5%. Regression correlation analysis performed to determine the relationship between two variables to determine the effect of growth and quality of alfalfa yield.The results showed that various rhizobium inoculated on Multiking 1, Vernal and Common failed and the unable to form viable root nodules. Several physiological parameters such as growth and photosynthetic rate, net assimilation rate and relative growth rate, showed significant differences between the combination treatment. Generally indicates that all combinations of treatments have relatively high levels of khlorofil, value between 1 to 3.3. Quality nutrients such as crude protein, crude fat, crude fiber, ash content and energy digestibility Variety Multiking 1, Vernal and Common are not significantly different. Nutritional quality and in vitro digestibility of Multiking1, Vernaland Common are not significantly different. Keywords : alfalfa varieties, type of rhizobium, growth, quality of yield, and in vitro digestibility

A recent assessment of the elemental composition of New Zealand pastures in relation to meeting the dietary requirements of grazing livestock1

An understanding of the benefits and limitations of pasture feeding underpins sustainable grazing systems that produce milk and meat from ruminant livestock. We evaluated the mineral composition of 1,106 pasture samples collected independently from locations across New Zealand from 2001 to 2006. About half were submitted during 2002 and 2003, and 87% came from the North Island. Most herbage was from ryegrass and clover-dominated swards. The concentrations of Ca, Co, Cu, Fe, K, Mg, Mn, Mo, Na, P, S, Se, or Zn were measured by nitric acid digestion followed by inductively coupled plasma optical emission spectroscopy or atomic absorption spectroscopy. Median concentrations for the macro elements were Ca 5.5, K 33, Mg 2.2, Na 2.0, P 4.0, and S 3.6 g/kg DM and for the trace elements were Co 0.10, Cu 8.4, Fe 131, Mn 74, Mo 0.66, Se 0.050, and Zn 43 mg/kg DM. Frequency histograms of concentrations revealed distributions ranging from near-normal to bottom-heavy skew with a long tail of high values. The minerals required for good plant growth were found at adequate concentrations in the majority of pastures. The exception was P; only 74% of pastures contained the recommended 3.5 mg P/kg DM. Results of the pasture survey were compared to the dietary intake requirements of cattle and sheep. For 7 elements, >95% of the pastures contained sufficiently high concentrations to meet the needs of unsupplemented animals. Exceptions were the Se dietary requirement, which was met by only 76% of pastures, the Co requirement of sheep met by only 54% of pastures, and the Cu, Na, and P requirements of cattle met by 25, 78, and 87% of pastures, respectively. Pasture analysis is an essential tool for identifying dietary insufficiency as well as unfavorable mineral balances where interactions could induce a deficiency, such as Cu × Mo and Mg × K. Monitoring of animals' nutritional status is also required to manage complex metabolic disorders related to peripartum flux of Ca and Mg. This study is the only large scale assessment of the mineral composition of New Zealand pastures to be published in 30 yr and the first to include a full range of trace elements. Knowing the proportion of pastures that are unlikely to meet nutritional requirements for some elements helps to define the risk areas for grazing livestock systems and provides an estimate of how prevalent mineral deficiencies might be if current practices of supplementation were not in place.

Effect of Sicilian pasture feeding management on content of α-tocopherol and β-carotene in cow milk

This study was performed to evaluate α-tocopherol and β-carotene contents of pasture milk under ordinary Sicilian farming conditions. Fourteen dairy farms were allocated into 2 balanced groups on the basis of cultivated (CULT) or spontaneous (SPO) pasture type feeding. Bulk milk per farm was collected 4 times from February through April at 3-wk intervals. Pasture botanical and diet composition, diet nutritional quality, milk yield and composition were estimated each time. Pasture intake levels were calculated based on feed analyses, hay and concentrate amounts fed, and milk yield and chemical composition. According to pasture intake, the farms were split into low pasture intake (LPI; <29.5% of dry matter) and high pasture intake (HPI; >29.5% of dry matter) groups. Milk samples per farm were analyzed for α-tocopherol and β-carotene contents by HPLC. The SPO group had higher levels of α-tocopherol and β-carotene in milk (0.7 and 0.3mg/L, respectively) and milk fat (19.0 and 7.5mg/kg fat, respectively) compared with the CULT group in milk (0.5 and 0.2mg/L, respectively) and milk fat (14.6 and 4.9mg/kg, respectively). High pasture intake compared with LPI increased α-tocopherol in milk fat (18.0 and 16.0mg/kg of fat, respectively). However, only in the SPO (not in CULT), HPI compared with LPI increased milk α-tocopherol (0.8 vs. 0.6mg/L, respectively), milk β-carotene (0.3 vs. 0.2mg/L, respectively), and milk fat β-carotene (8.4 vs. 6.6mg/kg, respectively). Results may be related to the different botanical composition of the respective pasture types and pasture intake. Spontaneous pasture compared with CULT contained a higher mass proportion of Asteraceae, Fabaceae, Cruciferae, Euphorbiaceae, and Malvaceae plants. Milk and milk fat α-tocopherol levels were higher on test-days (TD)-1, TD-2, and TD-4 compared with TD-3. For HPI farms, milk fat β-carotene content was higher on the first 2 TD compared with the last 2 TD. These differences could be related to plant biological stage. On Sicilian dairy farms, the highest milk α-tocopherol and β-carotene contents may be obtained feeding high levels of SPO pasture in the spring.

Improving pasture intake predictions by variable weighting of plant marker concentrations

It is difficult to measure pasture feed intake. A common method is based on naturally occurring, indigestible plant markers, such as long chain alkanes. Least-squares procedures are used to estimate diet composition and intake. If actual intake of a supplement is known, then total intake and the intake of all dietary components can be estimated. This ‘labelled-supplement’ approach requires an estimate of the faecal recoveries of the markers. The accuracy and precision of intake solutions for each animal is also affected by the sampling and measurement precision of the plant and faecal marker concentrations. This work was conducted to study whether weighting each marker's sums of squares in the least-squares procedure could be used to provide a more robust solution.Cluster and discriminant analyses of a plant marker database determined the contribution of each marker to discrimination between categories of plants. The markers’ cluster or discriminant weights were used to weight the sums of squares in the least squares procedures. The actual individual dry matter intakes (DMI) of 20 cattle were arbitrarily assigned for three different diets. Measurement and sampling variations in marker concentrations and/or faecal recoveries were simulated to generate predicted total pasture intakes around the actual values.Six marker weighting methods were compared for their DMI prediction error values and correlations between predicted and actual DMI: (A) all markers weighted by one; (B) separate cluster analyses of z scores for alkanes and alcohols; (C) combined cluster analyses for alkanes and alcohols; (D) discriminant analyses of z score marker data for plants categorized into grasses, legumes, shrubs and trees; (E) discriminant analyses of plants categorized on origin and plant, photosynthesis and reproduction type; and (F) discriminant analyses of plants categorized on plant, photosynthesis and reproduction type.The standard approach of weighting all markers by one (A) was satisfactory when marker concentration error was set at zero, however intake predictions were poor when the error was non-zero, which is likely. The weighted least-squares intake solutions that were more robust to variance in measured marker concentrations or in assumed faecal recovery rates were those using weights derived by methods D and F. Marker weights from Methods D, E and F resulted in similar intake prediction error variances and correlations. Methods E and F required more botanical information about plant species and method D was simpler, so method D is recommended rather than other methods studied here, including the standard method A. There are problems with using weights derived from an analysis of all published marker data, so better weighting methods may still be found for specific plant and marker datasets.

Milk volatile organic compounds and fatty acid profile in cows fed timothy as hay, pasture, or silage

Nutrient composition and organoleptic properties of milk can be influenced by cow diets. The objective of this study was to evaluate the forage type effects on volatile organic compounds, fatty acid (FA) profile, and organoleptic properties of milk. Timothy grass was fed as hay, pasture, or silage during a period of 27 d to a group of 21 cows in a complete block design based on days in milk. Each cow also received 7.2kg/d of a concentrate mix to meet their nutrient requirements. Forage dry matter intake averaged 13.9kg/d and was not different among treatments. Milk yield was higher for cows fed pasture, intermediate for cows fed silage, and lowest for cows fed hay. However, milk fat content was higher for cows fed hay and silage, compared with cows fed pasture. As a result, fat-corrected milk and fat yield were not different among treatments. Increasing the supply of dietary cis-9,cis-12 18:2 (linoleic acid) and cis-9,cis-12,cis-15 18:3 (α-linolenic acid) when feeding pasture enhanced the concentration of these 2 essential FA in milk fat compared with feeding hay or silage. Moreover, the ratio of 16:0 (palmitic acid) to cis-9 18:1 (oleic acid), which is closely related to the melting properties of milk fat, was lower in milk from cows on pasture than in milk from cows fed hay or silage. Cows fed hay produced milk with higher levels of several free FA and γ-lactones, but less pentanal and 1-pentanol. More dimethyl sulfone and toluene were found in milk of cows on pasture. Cows fed silage produced milk with higher levels of acetone, 2-butanone, and α-pinene. Results from a sensory evaluation showed that panelists could not detect a difference in flavor between milk from cows fed hay compared with silage. However, a significant number of assessors perceived a difference between milk from cows fed hay compared with milk from cows fed pasture. In a sensory ranking test, the percentage of assessors ranking for the intensity of total (raw milk, fresh milk, and farm milk), sweet (empyreumatic, vanilla, caramel, and sugar), and grassy (grass, leafy vegetable, and plant) flavors was higher for milk from cows fed pasture compared with hay and silage. Using timothy hay, pasture, or silage harvested at a similar stage of development, the current study shows that the taste of milk is affected by the forage type fed to cows. More research is, however, needed to establish a link between the sensory attributes of milk and the observed changes in volatile organic compounds and FA profile.