Dairy Cattle Feed Research Articles

A Survey on Aflatoxin M1 in Raw Milk of Fariman City, Khorasan Province, Iran

Background: Although milk is the valorous source of nutrition, consumption of aflatoxin M1 (AFM1) contaminated milk induces problems to human health. AFM1 is found in milk when dairy animals are fed with AFB1-contaminated feedstuff. AFM1 remains stable during milk pasteurization and storage as well as during the preparation of various dairy products. Objectives: The aim of the current study was to evaluate AFM1 contamination in raw milk of Fariman city. Materials and Methods: During the summer (July to September, 2012), 45 samples of raw milk were collected randomly from Fariman, Iran. The samples were analyzed with a commercial competitive enzyme-linked immunosorbent assay (ELISA) kit. Results: AFM1 was detected in all milk samples. The mean concentration of AFM1 was 11.61 ± 0.72 ng/L with a range of 6.3-23.3 ng/L. None of the samples had levels exceeding the maximum tolerance limit (50 ng/L) accepted by the European Union. Conclusions: AFM1 contamination of milk is not a concern in this city. However, dairy cattle feed samples of various livestocks must be regularly checked for aflatoxin and the storage conditions of feeds should be strictly controlled.

Supplementation of Heit-Chrose into Dairy Cow Feed Improves in Vitro Rumen Fermentation

The objective of the study was to evaluate the effect of Heit-Chrose (HC) supplementation using in vitro method on ruminal fermentation of dairy cattle. HC is a feed supplement containing allicin, saponin and organic minerals ( Se , Cr and Zn). This research was conducted using completely randomized design, with 6 treatments and 4 replications. The treatments were : 1). C = dairy cattle feed (CP 15.38%, CF 23.38%, TDN 61.26%); 2). HC-0 = C+ organic minerals (0.3 ppm Se + 0.15 ppm Cr + 40 ppm Zinc-lysinat) + 0 ppm of HC; 3). HC-15= C + 15 ppm HC; 4).HC-30 =C+ 30 ppm of HC; 5). HC-45 =C+ 45 ppm of HC; 6). HC-60 =C + 60 ppm of HC. Data obtained were analyzed using analysis of variance of SPSS program. HC supplementation increased the DMD, OMD, VFA, but reduced total gas, methane and protozoa count. HC supplementation greater than 30 ppm did not further improve ruminal fermentation. Supplementation at 30 ppm of HC to dairy cow feed was the appropriate level to improve the efficiency of rumen fermentation.

Supplementation of Heit-Chrose into Dairy Cow Feed Improves in Vitro Rumen Fermentation

The objective of the study was to evaluate the effect of Heit-Chrose (HC) supplementation using in vitro method on ruminal fermentation of dairy cattle. HC is a feed supplement containing allicin, saponin and organic minerals ( Se , Cr and Zn). This research was conducted using completely randomized design, with 6 treatments and 4 replications. The treatments were : 1). C = dairy cattle feed (CP 15.38%, CF 23.38%, TDN 61.26%); 2). HC-0 = C+ organic minerals (0.3 ppm Se + 0.15 ppm Cr + 40 ppm Zinc-lysinat) + 0 ppm of HC; 3). HC-15= C + 15 ppm HC; 4).HC-30 =C+ 30 ppm of HC; 5). HC-45 =C+ 45 ppm of HC; 6). HC-60 =C + 60 ppm of HC. Data obtained were analyzed using analysis of variance of SPSS program. HC supplementation increased the DMD, OMD, VFA, but reduced total gas, methane and protozoa count. HC supplementation greater than 30 ppm did not further improve ruminal fermentation. Supplementation at 30 ppm of HC to dairy cow feed was the appropriate level to improve the efficiency of rumen fermentation.

Determination of dietary starch in animal feeds and pet food by an enzymatic-colorimetric method: collaborative study.

Starch, glycogen, maltooligosaccharides, and other α-1,4- and α-1,6-linked glucose carbohydrates, exclusive of resistant starch, are collectively termed "dietary starch". This nutritionally important fraction is increasingly measured for use in diet formulation for animals as it can have positive or negative effects on animal performance and health by affecting energy supply, glycemic index, and formation of fermentation products by gut microbes. AOAC Method 920.40 that was used for measuring dietary starch in animal feeds was invalidated due to discontinued production of a required enzyme. As a replacement, an enzymatic-colorimetric starch assay developed in 1997 that had advantages in ease of sample handling and accuracy compared to other methods was considered. The assay was further modified to improve utilization of laboratory resources and reduce time required for the assay. The assay is quasi-empirical: glucose is the analyte detected, but its release is determined by run conditions and specification of enzymes. The modified assay was tested in an AOAC collaborative study to evaluate its accuracy and reliability for determination of dietary starch in animal feedstuffs and pet foods. In the assay, samples are incubated in screw cap tubes with thermostable α-amylase in pH 5.0 sodium acetate buffer for 1 h at 100°C with periodic mixing to gelatinize and partially hydrolyze α-glucan. Amyloglucosidase is added, and the reaction mixture is incubated at 50°C for 2 h and mixed once. After subsequent addition of water, mixing, clarification, and dilution as needed, free + enzymatically released glucose are measured. Values from a separate determination of free glucose are subtracted to give values for enzymatically released glucose. Dietary starch equals enzymatically released glucose multiplied by 162/180 (or 0.9) divided by the weight of the as received sample. Fifteen laboratories that represented feed company, regulatory, research, and commercial feed testing laboratories analyzed 10 homogenous test materials representing animal feedstuffs and pet foods in duplicate using the dietary starch assay. The test samples ranged from 1 to 70% in dietary starch content and included moist canned dog food, alfalfa pellets, distillers grains, ground corn grain, poultry feed, low starch horse feed, dry dog kibbles, complete dairy cattle feed, soybean meal, and corn silage. The average within-laboratory repeatability SD (sr) for percentage dietary starch in the test samples was 0.49 with a range of 0.03 to 1.56, and among-laboratory repeatability SDs (sR) averaged 0.96 with a range of 0.09 to 2.69. The HorRat averaged 2.0 for all test samples and 1.9 for test samples containing greater than 2% dietary starch. The HorRat results are comparable to those found for AOAC Method 996.11, which measures starch in cereal products. It is recommended that the dietary starch method be accepted for Official First Action status.

Sustainability of Corn Stover Harvest Strategies in Pennsylvania

Pennsylvania farmers have a long history of harvesting corn (Zea mays L.) stover after grain harvest for animal bedding and feed or as a component of mushroom compost, or as silage for dairy cattle feed. With the shallow soils and rolling topography, soil erosion and carbon losses have been minimized through extensive use of cover crops, no-till, and organic matter additions from animal manure. Our objective was to determine the effect of harvesting corn stover as a feedstock for bioenergy production in continuous corn or corn–soybean [Glycine max (L.) Merr.] rotations on corn grain and stover yields, soil carbon, nitrogen, phosphorus, potassium, and the potential for cover crops to mitigate negative impacts of stover harvest. Although there was not a significant effect of stover harvest on corn grain yields in continuous corn, stover harvest tended to increase yields in years with wet springs but decreased them in dry years. Under the corn soybean rotation, 100 % stover removal always resulted in lower grain yields. The harvest index (HI) varied from 0.45 to >0.6 over the 5-year period with the lowest HI values being in response to a late summer drought and highest values being associated with an early summer drought. In most cases, 60 % soil cover was maintained in fall and spring with 50 % harvest of corn stover. Without a rye (Secale cereale L.) cover crop, surface residue for 100 % stover harvest ranged from 20 to 30 %, whereas it was greater than 40 % when rye was established promptly in the fall. Soil carbon was similar across stover removal levels, crop rotations, and cover crops, as were soil nitrogen, phosphorus, and potassium concentrations, since nutrient removal by the grain and stover were replaced with fertilizer additions. Based on the crop yield, surface cover, and soil nutrient responses, partial stover removal could be sustainable under typical climate and management practices in Pennsylvania.

Minerals Profile of Soil, Feed, Fodder and Serum of Dairy Cattle in North Eastern Ghat (NEG) of Odisha

A survey based study was planned in North Eastern Ghat (NEG) of Odisha to analyse the mineral profile of soil, feed, fodder and serum of dairy cattle. This agro-climatic zone comprises of four districts namely Kandhamal, Ganjam, Raygada and Gajapati. Amongst those two districts viz Ganjam and Gajapati are taken for the study considering the density of dairy cattle population. In the similar manner two Blocks from Ganjam District namely Khallikote, Kukudakhandi and two blocks from Gajapati District namely Mohana, R.Udayagiri was considered for our experimental area with two villages from each of the block. Macro and micro minerals like Calcium (Ca), Phosphorus (P), Zinc (Zn), Copper (Cu), Manganese (Mn) and Iron (Fe) were estimated for soil, feed, fodder and serum. Soil Ca was estimated by rapid titration method and available soil phosphorus was determined by colorimetric analysis. The soil micro minerals like Cu, Fe, Zn and Mn were analyzed as per the method of Lindsay and Lindsay (1978). Dry ash and Wet ash method were used for analysis of macro and micro minerals respectively for feed and fodder. The concentration of Ca and P in serum was estimated by using the kit method. The serum micro minerals like Cu, Fe, Zn and Mn were estimated by Atomic Absorption Spectrophotometer method. The findings depicted that cattle of this region are severely deficient in Ca, Zn, and Cu and marginally deficient in P and Mn with higher value of Fe content than the respective critical levels. Considering the importance of productivity and reproductive performance of dairy animal an area specific mineral mixture must be prepared and fed to the animals to meet the deficiencies of these minerals.

Methods to Evaluate Rumen Protected Lysine for Dairy Cows

There are many rumen protected amino acid products available for dairy cattle feeding. However, feed formulation programs require values related to rumen solubility, rate of disappearance in the rumen and total tract digestibility and often such values are not available. In vivo testing procedures are complex, time consuming and expensive. This study was conducted to determine if a newrapid, lower cost in vitro method developed for feed ingredients could be applied to a rumen protected lysine product (DairynatLys-30, Jefo Nutrition Inc). In vivo determination of the rapidly solubilized protein fraction, rate of degradation of the slowly solubilized fraction and total tract digestibility studies were compared to the in vitro method in use in many ingredient analysis laboratories for feed ingredients such as forages, protein supplements and grains. Results showed that the rapidly soluble fraction (8.33% and 8.66% of total N for in vivo and in vitro methods) and rates of disappearance in the rumen (2.64%/h and 2.43%/h for in vivo and in vitro procedures) compared favorably between the two methods for the rumen protected product. Total tract digestibility values were slightly higher (84.4%) with the in vivo method used than with the in vitro method (75.9%), and both are in the expected calculated range of digestibility of 80%. In conclusion the in vitro method appears to be an acceptable alternative for evaluating rumen protected amino acids.

Management and use of dairy cattle feed resources on smallholder certified organic pineapple farms in Central Uganda

Formulation of exclusively organic diets that meet maintenance and production requirements of dairy cattle is a major limitation to production of premium organic products of animal origin. This study was therefore carried out to assess the use and availability of feed resources and the coping strategies used by farmers to overcome dry season feed shortages on 64 smallholder certified organic pineapple farms. Data was collected using semi-structured questionnaires and two focus group discussions. Majority of households were headed by males (62.9%) while average age of respondents was 42.5 years. Farmers allocated more land (P<0.05) to organic pineapple production compared to livestock. Beside dairy cattle, farmers also kept chickens, goats and pigs. Tethering was the commonest cattle management system. Fifty three percent of respondents reported using both natural pastures and crop residues as major dairy cattle feed resources while only 19% reported using elephant grass. Banana peels (25.1%) and sweet potato vines (24.7%) were the most important crop residues fed to cattle. Farmers reported high cost of concentrates and scarcity of feeds as their biggest challenges in dairy cattle production. Of the respondents, 51.4% conserved feed for their cattle as fodder banks. As a coping strategy to feed shortages, majority (42.9%) of farmer scavenged for feed resources from both organic certified and nonorganic neighbouring farms which is contrary to organic livestock farming standards. It was, therefore, concluded that management of livestock feeding in the study area fell short of the requirements for organic livestock feeding standards. Research to develop strategies that can use alternative on-farm feed resources through ensiling organic pineapple wastes during the dry season is recommended as a long term strategy to address feed challenges for organic livestock farmers.

Annual and regional variations of aflatoxin B1 levels seen in grains and feed coming from Croatian dairy farms over a 5-year period

The aim of the study was to investigate annual and regional differences in the level of aflatoxin B1 (AFB1) in grains and dairy cattle feed. Maize (n ¼ 972), wheat (n ¼ 201), barley (n ¼ 147), oat (n ¼ 136), grain mixtures (n ¼ 168), and dairy cattle feed (n ¼ 325) were sampled from 2009 to 2013 on different farms and in different farm factories situated in four Croatian regions. The samples were analysed for AFB1 using the validated ELISA immunoassay. AFB1 was determined in 16.4% of all investigated samples, among which maize was proven to be the most contaminated, with 21.7% of the samples recovered during 2013 harbouring AFB1 in concentrations over the permissible ones. Levels higher than permitted were observed in 17.9% and 12.3% of grain mixtures and dairy cattle feed, respectively, whereas concentrations of AFB1 determined in other crops throughout the investigated period met the stipulated requirements. The results revealed the AFB1 occurrence to be significantly (p < 0.05) dependent on the cultivation region, with the highest levels generally found in maize harvested in 2013 and consequently in grain mixtures and cattle feed that can most likely be associated with climatic conditions as the most critical factor for mould formation, and thus also AFB1 production.

An overview on single nucleotide polymorphism studies in mastitis research

Mastitis is an inflammatory condition of the mammary gland caused by microorganisms as diverse as bacteria, viruses, mycoplasma, yeasts and algae. Mastitis is an economically devastating disease mainly affecting the crossbred cattle in India. Control strategies against mastitis includes antibiotic therapy, vaccination, improvements in dairy cattle husbandry, farm and feeding management etc. but has met with little success.. Mastitis tolerance/susceptibility is difficult to measure directly and hence milk somatic cell count (SCC) or milk somatic cell score (SCS) is used as an indicator trait for mastitis as both traits are highly positively correlated. Single nucleotide polymorphism ) marker is a single base change in a DNA sequence at a given position. SNP markers are the most preferred genetic markers nowadays. Currently most researches worldwide have been targeting molecular high density SNP markers that are linked to mastitis tolerance in an attempt to incorporate to understand the genetics of host resistance to mastitis and this knowledge will be helpful in formulating breeding programmes in an attempt to control mastitis. This article reviews various SNPs which are reported to be significantly associated with mastitis tolerance/susceptibility. mastitis, single nucleotide polymorphism, somatic cell count. (SNP

Original Research Article Milk Yield and Feed Conversion of Sokoto Gudali Cows Fed Elephant Grass Ensiled with Cassava Peel

Abstract Year-round availability of feed is a major concern for dairy farmers in many parts of the tropics. Silage making is a reliable means of providing feed for dairy cattle during periods of forage scarcity. In this study, Elephant grass (EG) (Pennisetum purpureum) was ensiled with cassava peel (CSP) at 0, 10, 30 and 50% levels of inclusion on a wet basis. At 21, 42 and 63 days of ensiling, silage samples were taken for chemical analysis and the remaining materials were fed to four lactating Sokoto Gudali cows for a period of 84 days using a Latin square design. Dry matter (DM) content of silage mixtures increased from 18.22 to 28.70% as level of CSP in the silage mixture increased while crude protein (7.33 to 6.08%) and crude fibre (32.80 to 23.95%) decreased. Dry matter intake of cows, milk yield and feed conversion ratio (FCR) varied (P &lt; 0.05) with inclusion of cassava peel in the silage mixtures. Dry matter intake of cows increased from 2.56 to 3.84% of body weight (BW) and milk yield from 2.90 to 6.70 kg/d as proportion of CSP in the grass silage increased. Feed conversion ratio of cows ranged from 2.08 to 3.23 and improved with inclusion of CSP in the silage. These results show that addition of cassava peel to Elephant grass silage improved intake and milk production in Sokoto Gudali cows fed Elephant grass silage.

Caracterización energética y proteica de materias primas de origen animal empleadas en la formulación de alimentos balanceados para vacas lecheras.

Energetic and proteic characterization of prime sources of animal origin used in the formulation of a balanced feed for dairy cattle. The kinetics of ruminal degradation of dry matter, crude protein and ether extract were determined for fish, meat and bone, and poultry meals. These meals of animal origin showed characteristics proper of the species of origin, not only in the soluble fraction but also in the rates of ruminal degradability of the potentially degradable fraction. Based on the results of degradation after 48 hours of ruminal incubation, the true digestible contents of the protein and the digested ether extract were determined biologically, making the measurement of the total digestible nutrients, and the concentration and net rate of digestible energy and feed, more precise than determinations by chemical methods. The concentrations of energy for milk production was 2.02, 1.66, and 2.60 Mcals/kg for fish, meat and bone, and poultry meals, respectively. The fraction of soluble protein (A) was high in fish meal (75.29%), intermediate in meat and bone (46.83%), and low in poultry (25.75%), with a degradable fraction (B) of 10.62, 27.66, and 42.06%, along with an insoluble fraction (C) of 14.09, 25.51, and 32.19%, respectively. The degraded protein in the rumen was 83.23, 66.25, and 51.98% in the same order cited above. The contents of crude protein effectively retained by the animals during the whole digestive process were 53.29, 51.86, and 42.05% for fish, meat and bone and poultry meals, respectively.

Physical Characteristics of Pressed Complete Feed for Dairy Cattle

The study was aimed to evaluate the physical characteristics of the pressed complete feed in the forms of cube, cylinder and ball. The study was conducted to get a complete feed of dairy cows that can be developed commercially. The evaluation was done on a physical test : bulkiness, hardness and hygroscopic properties of pressed complete feeds. The results of this research showed that the bulkiness of pressed complete feed in the forms cubes, cylinders and balls were between 0.20 up to 0.48 liter/kg; the hardness of pressed complete feed, cylinders and balls were 3 lbs up to 14 lbs; the hygroscopic factor of pressed complete feed in the forms cubes, cylinders and balls were around 1.10% up to 9.69%. The pressed complete feed in the forms of cube and cylinder are better than the form of ball in physical characteristics. doi: 10.12777/ijse.4.2.2013.61-65

Supplementation of Sapindus rarak and Garlic Extract in Feed Containing Adequate Cr, Se, and Zn on Rumen Fermentation

The objective of the study was to evaluate the effect of Sapindus rarak extract (SRE) with or without garlic extract (GE) on in vitro ruminal fementation. This research was conducted experimentally with a randomized block design, with 7 treatments and 5 blocks. The treatments were: R0: dairy cow feed; R1: R0 + 1.5 ppm Cr + 0.3 ppm Se + 40 ppm Zn; R2: R1 + 1.8 g/kg methanol extract of lerak fruit meal (SRE); R3: R2 + 0.25 ppm of garlic extract (GE); R4: R2 + 0.50 ppm of GE; R5: R2 + 0.75 ppm of GE; R6: R2 +1.0 ppm of GE. The results showed that the supplementation of SRE alone or without GE did not affect the pH, however, it decreased crude fiber digestibility. The supplementations of SRE and GE, decreased crude fibre digestibility as much as 13.01% up to 16.6%. The supplementation of 1.8 g/kg SRE + 0.25 ppm GE in the dairy cattle diet was able to decrease ace-tate, protozoal population and increase propionate. The supplementation of 1.8 g/kg SRE and 0.25 ppm garlic represents the best combination for dairy cattle feed in improving ruminal fermentation based on feed digestibility, fermentation products, and rumen bacterial population.

Fungi and mycotoxins in silage: an overview

The present revision shows the early and current knowledge in the field of silage fungi and mycotoxins explaining the relevance of fungi and mycotoxins in silage. The problem does not end in animal disease or production losses as mycotoxins in feed can lead to the presence of their metabolic products in dairy products, which will be eventually affecting human health, mainly infants. Silage is green forage preserved by lactic fermentation under anaerobic conditions. This ecosystem maintains its quality and nutritional value depending on interactions among physical, chemical and biological agents. Forages used for ensilage are naturally in contact with yeasts and filamentous fungi, and the contamination often occurs in the field and can also occur during harvesting, transport, storage. Moreover, postharvest poor management can lead to a rapid spoilage. Studies on fungal contamination of dairy cattle feed have shown how corn silage influences the contamination degree of feed supplied to livestock. Increasing knowledge in this area will help elucidate the influence that this microbiota exerts on production and/or degradation of mycotoxins present in silage. Some of these fungi, although opportunist pathogens, are relevant epidemiologically and represent a high risk of contamination to farm workers who handle them improperly.

Physical Characteristics of Pressed Complete Feed for Dairy Cattle

The study was aimed to evaluate the physical characteristics of the pressed complete feed in the forms of cube, cylinder and ball. The study was conducted to get a complete feed of dairy cows that can be developed commercially. The evaluation was done on a physical test : bulkiness, hardness and hygroscopic properties of pressed complete feeds. The results of this research showed that the bulkiness of pressed complete feed in the forms cubes, cylinders and balls were between 0.20 up to 0.48 liter/kg; the hardness of pressed complete feed, cylinders and balls were 3 lbs up to 14 lbs; the hygroscopic factor of pressed complete feed in the forms cubes, cylinders and balls were around 1.10% up to 9.69%. The pressed complete feed in the forms of cube and cylinder are better than the form of ball in physical characteristics. doi: 10.12777/ijse.4.2.2013.61-65

Feed–milk–manure nitrogen relationships in global dairy production systems

Nitrogen (N) inputs from fertilizer, biologically-fixed N, feed, and animal manure sustain productive agriculture. Agricultural systems are limited however in their ability to incorporate N into products, and environmental N losses may become local, regional and global concerns. The anticipated increases in global demand for food, especially for animal products, necessitate an urgent search for practices that enhance N use efficiency (NUE) and reduce environmental N loss. The objectives of this study were to determine feed–milk–manure N relationships for the global dairy herd, and to evaluate how well regional and production system determinations of these relationships correspond to measurements made under experimental conditions and on commercial dairy farms. Data on dairy cattle populations, feed and milk production from 142 countries were used in a Life Cycle Assessment (LCA) model to determine dry matter intake (DMI), N intake (NI), the percentage of NI secreted as milk N (NUE-milk), the percent of NI used by the whole-herd (NUE-herd), and manure N excretion (Nex). On a global basis, an average lactating cow weighs approximately 420kg; per animal unit (AU=1000kg live weight) daily DMI and NI are 21.0kg and 477g, respectively; annual milk production is 5000kg/AU; and NUE-milk and NUE-herd are 16.0% and 15.6%, respectively. Approximately 37% of global lactating cows have NUE-milk of <10% and these low efficient cows account for 10% of the milk production and 33% of Nex globally. Approximately 30% of global lactating cows have NUE-milk between 21% and 25% and these cows account for 53% of the milk production and 35% of Nex globally. Estimates of NUE-milk and Nex corresponded well to measurements under experimental and commercial farm conditions. Study determinations of Nex were however 3–50% lower than IPCC Tier 1 values of Nex for Africa, Middle East, Latin America and Asia. The apparent accuracy of LCA model calculations of Nex should enhance regional, production system and global determinations of dairy Nex loss during collection, storage, and land application, and the amounts of Nex actually recycled through crops and pastures.

Status of animal feed resources in Rwanda

Animal feed resources remain a major constraint for livestock development in tropical Africa. In Rwanda, grazing lands are shrinking sharply because crop cultivation is progressively encroaching on grazing areas with increasing human pressure (Mutimura and Everson 2011). Therefore, over 60% of households cultivating less than 0.7 ha, and owning livestock, practize zerograzing, where farmers cut-and-carry forage and crop residues to feed animals that are kept exclusively under sheds (MINAGRI 2009). In general, the main feed for dairy cattle under a zero-grazing system is Napier grass (Pennisetum purpureum). For more than a decade, efforts to improve the feed resource base and feeding management have been based on the introduction, characterization and evaluation of exotic forage species, including grasses and legumes. The main aim of this study was to identify and document the status of improved forages as animal feed resources and for use in environmental protection in Rwanda.

Capacidade de uso de solo das propriedades rurais na microbacia do córrego Guará no Município de Marechal Cândido Rondon/PR

Soil is a finite resource, limited and non-renewable. The type of soil management is crucial to the sustainability of hydrological and productive potential of a watershed. This study aimed to diagnose the current state of the watershed of the Guara River, performing characterizations of the physical and environmental management tools such as use territorial environmental and land. The investigative unit was the soil in order to find the main agents of degradation, and finally recommend the best ways to watershed management, minimizing soil degradation.The land use is the most relevant for agriculture (65.9%) cultivated with soybeans, corn and wheat. The area used for pasture was (11.8%) used for dairy cattle feeding. The watershed has slopes 0-13 degrees, it reducing the risk of erosion. In the analyzed properties, the main obstacles were risk of erosion, stoniness, and flood risk. The watershed has a great capacity for agriculture, and areas not suitable for agriculture, appear suitable for grazing and forestry.

Carbon dynamics and retention in soil after anaerobic digestion of dairy cattle feed and faeces

Animal manure and plant biomass are increasingly used for methane production. While minerals may be conserved during gas generation, the composition of the biogenic material is changed and less carbon (C) is returned to the soil in the digested residue. We evaluated the fate of C in ruminant feed treated differently before added to soil: no treatment (feed), anaerobic digestion (digested feed), consumed by cattle (faeces), consumed by cattle and anaerobic digestion (digested faeces). The materials were incubated for 245 days at 20 °C. The net CO2 release was determined and fitted to a kinetic C model (pool half-lives: 4, 20 and 100 days). During anaerobic digestion, gaseous C losses were 80 and 46% of the C in feed and faeces, respectively. The model predicted that 14, 58, 48, and 76% of the C applied in feed, digested feed, faeces and digested faeces are retained in soil after 1 to 2 years. When C lost during the pre-treatments was included, the long-term C retention in soil accounted for 12–14% of the C initially present in the feed. We conclude that soil microbial activity is reduced when residues are anaerobically digested for biogas before being applied to soil. However, the retention in soil of C over decades to centuries appears to be similar whether the initial turnover of plant biomasses occurs in the soil, in the digestive tract of ruminants, in an anaerobic reactor or in a combination of the latter two.