Winter Pasture Research Articles

The role of traditional farming practices in ecosystem conservation: The case of transhumance and vultures

Transhumance is a traditional livestock practice based on the movement of livestock between winter and summer pastures with importance placed on biodiversity conservation. We analyzed the transhumant activity of sheep and cows in the uplands of the Cantabrian Mountains, NW Spain, and its influence on the ecology and management of the griffon vulture, a scavenger with a relevant ecosystem function. For the first time, we provided strong evidence of the close relationship between vultures and transhumance, which was previously only suggested. Vultures occupied roosting sites very close to the summer pastures and often consumed livestock carcasses. There was a strong spatiotemporal adjustment in the use of these mountain areas by transhumant livestock, especially sheep, and vultures. The number of transhumant sheep and cows within 10–12.5 km around the roosts were the best predictors of vulture occurrence and abundance, respectively, in generalized linear mixed models. Our estimates of potentially available food from livestock carcasses for vultures indicated that our study area can maintain important griffon vulture populations through a system based on traditional livestock farming including transhumance. Thus, transhumance is able to influence the top of the ecosystem (scavengers) and could aid in sustainable management of griffon vulture populations. In our study area, transhumant sheep were reduced by 62% in the last 15 years and only 20% of summer pastures are now occupied. The potential impact that the ongoing loss of transhumant activity could have on mountain ecosystem conservation should be assessed and taken into account by the new European Common Agricultural Policy.

Effects of supplemental dietary tannins on the performance of white-tailed deer (Odocoileus virginianus)

Tannins are natural and nutritionally significant components of the diets of browsing ungulates. In trials on supplemented pastures and in drylots, we estimated dry matter intake (DMI), weight gain, and urea N, potassium, cortisol and creatinine in urine of captive white-tailed deer fed pelleted diets that differed only in the respective quebracho tannin (QT) content. The low control, medium and high QT rations were 3.6, 63 and 152 g/kg DM respectively. There was no tannin-free pellet option. Trials were divided into winter pasture, restricted choice and spring growth. In winter pasture trial on pasture using QT, deer reduced QT intake relative to that expected under random foraging. This aversion was also apparent during the spring growth trial. While DMI in the winter pasture trial remained similar among treatments (p > 0.05), averaging 130 g/kg(0.75)/day, deer gained more weight (p < 0.05) when given a choice that included the high QT ration. During subsequent spring growth, DMI and weight gains generally exceeded those of the winter period. Unlike the winter pasture trial, weight gains in spring growth trial were higher (p < 0.05) in the low-control QT treatment. In the restricted choice trial, weight gain was again higher (p < 0.05) for deer fed a low-control QT diet. The urea N/creatinine ratio of deer fed the low-control QT diet (0.0357) was over three times that of deer fed the high QT diet (0.0107). Neither potassium/creatinine nor cortisol/creatinine ratios were affected by diet (p > 0.05). Collectively, these results suggest that although deer do not avoid tannins, and even ingested up to 5% under the choice options in these trials, the effect of tannins on deer performance may vary by season as well as by foraging opportunities.

A preliminary survey of zearalenone and other mycotoxins in Australian silage and pasture

The oestrogenic mycotoxin zearalenone can occur in pasture and fodder infected with various Fusarium spp., and at concentrations exceeding 1 mg/kg, it has been associated with a reduction in the fertility of grazing ruminants. Pasture and fodder samples collected in four small studies from cattle and sheep farms in south-eastern Australia were tested for zearalenone and other mycotoxins using high performance liquid chromatography. Zearalenone in winter pasture was detected (viz. &gt;0.1 and up to 5.0 mg/kg DM) in 8 of 22 pastures; three exceeded the tolerance concentration, 1.0 mg/kg. Zearalenone was detected in 15 of 24 samples of silage that were submitted by farmers for nutritional assessment, but that were not suspected of toxicity; 12 were in the range 1.0–80 mg/kg. Zearalenone was correlated with crude protein concentration (r = 0.59, P &lt; 0.05); it was high in legume-dominant compared with grass-dominant silage (P &lt; 0.04). In a separate investigation of 28 feed samples submitted for mycotoxin screening by nutritionists/veterinarians, zearalenone was detected in 7 of 13 pastures, in two of two hays and 9 of 13 silages (6 of 28 exceeded 1 mg/kg). Deoxynivalenol was detected in 6 of 13 pastures, one of two hays and 10 of 13 silages. Deoxynivalenol was high (0.64–1.76 mg/kg) in five silages of excellent/average appearance. Ergovaline and lolitrem B were detected at above tolerable concentrations in four of eight perennial ryegrass-dominant samples examined. Aflatoxins, ochratoxin A and fumonisins were detected in some samples although the concentrations were low. Two samples contained either zearalenone and ergovaline, or zearalenone and deoxynivalenol, where both mycotoxins exceeded tolerable concentrations.

Climate change effects on pasture systems in south-eastern Australia

Climate change projections for Australia predict increasing temperatures, changes to rainfall patterns, and elevated atmospheric carbon dioxide (CO2) concentrations. The aims of this study were to predict plant production responses to elevated CO2 concentrations using the SGS Pasture Model and DairyMod, and then to quantify the effects of climate change scenarios for 2030 and 2070 on predicted pasture growth, species composition, and soil moisture conditions of 5 existing pasture systems in climates ranging from cool temperate to subtropical, relative to a historical baseline. Three future climate scenarios were created for each site by adjusting historical climate data according to temperature and rainfall change projections for 2030, 2070 mid- and 2070 high-emission scenarios, using output from the CSIRO Mark 3 global climate model. In the absence of other climate changes, mean annual pasture production at an elevated CO2 concentration of 550 ppm was predicted to be 24–29% higher than at 380 ppm CO2 in temperate (C3) species-dominant pastures in southern Australia, with lower mean responses in a mixed C3/C4 pasture at Barraba in northern New South Wales (17%) and in a C4 pasture at Mutdapilly in south-eastern Queensland (9%). In the future climate scenarios at the Barraba and Mutdapilly sites in subtropical and subhumid climates, respectively, where climate projections indicated warming of up to 4.4°C, with little change in annual rainfall, modelling predicted increased pasture production and a shift towards C4 species dominance. In Mediterranean, temperate, and cool temperate climates, climate change projections indicated warming of up to 3.3°C, with annual rainfall reduced by up to 28%. Under future climate scenarios at Wagga Wagga, NSW, and Ellinbank, Victoria, our study predicted increased winter and early spring pasture growth rates, but this was counteracted by a predicted shorter spring growing season, with annual pasture production higher than the baseline under the 2030 climate scenario, but reduced by up to 19% under the 2070 high scenario. In a cool temperate environment at Elliott, Tasmania, annual production was higher than the baseline in all 3 future climate scenarios, but highest in the 2070 mid scenario. At the Wagga Wagga, Ellinbank, and Elliott sites the effect of rainfall declines on pasture production was moderated by a predicted reduction in drainage below the root zone and, at Ellinbank, the use of deeper rooted plant systems was shown to be an effective adaptation to mitigate some of the effect of lower rainfall.

Komi reindeer herding: the effects of socialist and post-socialist change on mobility and land use

This paper contributes to the discussion concerning the way in which Soviet state policies have influenced the lives, social organization, economy and culture of a group of indigenous Komi reindeer herders of northern Russia: its main focus is to explain how these policies have changed the herders’ patterns of migration and land use. Extensive anthropological fieldwork—to determine current and past herding practices—was carried out and archives were thoroughly investigated to document land use changes in relation to state reindeer herding policies. It was found that compared with those of several decades ago, the migration routes are now much shorter, as the herders have abandoned large areas of winter pastures located in the southernmost part of their herding territory. This “abandonment” phenomenon is endemic amongst reindeer herders generally, throughout the Komi Republic. Whereas the reasons for the abandonment of winter pastures are diverse, they can be attributed mostly to the state sedentarization policy, which has modified the family structures of herders, and the continuing decreases in state subsidies that have changed the balance between state and private ownership of reindeer. Both these factors have greatly contributed to the herders’ dependence on visiting towns, where they now own flats, and on selling reindeer products, upon which they are increasingly reliant for financial security.

Balanço do carbono orgânico no solo sob integração lavoura-pecuária no sul do Brasil

A integração lavoura-pecuária tem apresentado um avanço recente em áreas historicamente utilizadas com pecuária de corte extensiva no sul do Brasil. O inadequado manejo das pastagens de inverno associado ao uso da monocultura da soja no verão podem limitar o aporte de resíduos vegetais ao solo e reduzir os estoques de C orgânico do solo. O objetivo deste trabalho foi avaliar o impacto do aumento da freqüência de pastejo no inverno e de sistemas de culturas de verão no estoque de C orgânico total do solo (COT). O experimento, realizado por quatro anos sob sistema plantio direto, seguiu um delineamento de blocos ao acaso, em arranjo bifatorial 3x3, com quatro repetições. O fator A foi constituído por três intervalos de pastejos durante o inverno: sem pastejo (SP), pastejo a cada 28 dias (P28) e pastejo a cada 14 dias (P14). O fator B constou de três sistemas de culturas de verão: monocultura de soja (Mon-S), monocultura de milho (Mon-M) e rotação anual de soja e milho (Rot-S/M). Foram quantificadas as adições de C ao solo via resíduos vegetais e os estoques de COT do solo segundo os métodos de camada e massa equivalentes de solo. O aumento da freqüência de pastejo diminuiu o aporte de C oriundo das pastagens de inverno de 5,3 Mg ha-1 no tratamento SP, para 1,7 e 1,3 Mg ha-1 nos tratamentos P28 e P14, respectivamente. O milho foi a cultura que proporcionou o maior aporte de C ao solo, com uma média de 6,0 Mg ha-1, enquanto a soja adicionou apenas 2,2 Mg ha-1. Os estoques de C orgânico calculados com base em camadas equivalentes de solo foram superestimados nos tratamentos P14 e P28 e subestimados no tratamento SP em comparação aos resultados obtidos com base nas massas equivalentes de solo, que foram utilizados para comparação dos sistemas de manejo. Os estoques de C orgânico nas camadas de 0-0,025, 0,025-0,05 e 0,05-0,10 m foram linearmente relacionados à adição anual de C pelas culturas (pastagem + culturas anuais), sendo necessária a adição de 4,48 Mg ha-1 ano-1 para a manutenção do estoque original de C orgânico da camada de 0-0,10 m. A baixa adição de C ao solo pelos resíduos vegetais no tratamento P14 resultou numa emissão líquida estimada de C para a atmosfera (0,05 a 0,27 Mg ha-1 ano-1 ), enquanto o solo no tratamento SP atuou como um dreno de C atmosférico (0,19 a 0,30 Mg ha-1 ano-1). No tratamento P28, o comportamento do solo como fonte ou dreno de C dependeu do sistema de cultura de verão, tendo sido estimada uma emissão líquida de C do solo sob Mon-S (0,04 Mg ha-1 ano-1 ) e uma retenção líquida de C sob Mon-M (0,15 Mg ha-1 ano-1 ) e Rot-S/M (0,11 Mg ha-1 ano-1 ). O maior intervalo entre pastejos, durante o inverno, associado à utilização do milho no verão contribuiu para maiores adições de resíduos vegetais e acúmulo de C orgânico no solo.

Comportamento ingestivo de cordeiras em pastagem consorciada de inverno sob diferentes intensidades de desfolha

Avaliou-se a relação entre a estrutura do pasto, as variáveis ambientais e o comportamento ingestivo de cordeiras Ile de France × Texel em pastagem consorciada de aveia-preta (Avena strigosa Schreb.), azevém (Lolium multiflorum Lam.) e trevo-vermelho (Trifolium pratense L.) sob quatro intensidades de desfolha (muito alta, alta, média e baixa). Utilizaram-se pastejos intermitentes considerando a soma térmica de 300 graus-dia como critério para determinar os intervalos de pastejo. As avaliações do comportamento ingestivo foram feitas por meio de observação visual em quatro períodos contínuos de 24 horas realizados no período de maio a outubro de 2006. O maior tempo de pastejo ocorreu na intensidade baixa. Altas intensidades de desfolha ocasionaram aumento da densidade populacional de perfilhos de azevém e não alteraram o peso desses perfilhos. A massa de bocados e a qualidade da dieta selecionada pelas cordeiras foram semelhantes entre as intensidades testadas. Em pastagem de aveia+azevém+trevo-vermelho, quando o intervalo de pastejo é determinado pela soma térmica de 300 graus-dia, a utilização de intensidades de desfolha que variam de baixa a muito alta não altera o comportamento ingestivo de cordeiras. O comportamento ingestivo é afetado pelo ciclo do pasto e pelo fotoperíodo e a seletividade dos animais reduz ao final do período de utilização da pastagem, quando ocorre aumento no tempo de pastejo e na distância percorrida em busca de locais de alimentação.

Yield and Nutritive Value of ‘Spring Green’ Festulolium and ‘Jesup’ Endophyte‐Free Tall Fescue Stockpiled for Winter Pasture

Pasture‐based dairies in the Midwest have a difficult time providing high‐quality pasture during winter. Little is known about the yield and nutritive value of festulolium when stockpiled for winter grazing compared to tall fescue. In this study, the yield and nutritive value of ‘Jesup’ endophyte‐free tall fescue [Schedonorus phoenix (Scop.) Holub.] and ‘Spring Green’ festulolium [Festulolium loliaceum (Hudson) P.V. Fournier] were evaluated monthly from November to March over three years. The research was conducted near Mt. Vernon, MO, on a Gerald silt loam (fine, mixed, active, mesic Aeric Fragiaqualf). In two of the three years, stockpiled tall fescue out‐yielded festulolium by as much as 930 kg ha−1 Both tall fescue and festulolium yields decreased over winter by approximately the same percentage; losses from November to March ranged from 32 to &gt;75%. The nutritive value of stockpiled festulolium was consistently greater than stockpiled tall fescue during winter. Both stockpiled festulolium and tall fescue contain sufficient crude protein and total digestible nutrients at one times maintenance to maintain most small breed dairy cows during their dry period but would be severely lacking once lactation started. Despite the greater nutritive value of stockpiled Spring Green festulolium compared to Jesup tall fescue, the low forage yield of festulolium makes its use questionable for pasture‐based dairies.

Availability of gastro-intestinal nematode larvae to sheep following winter contamination of pasture with six nematode species on the Northern Tablelands of New South Wales

This experiment was designed to determine the infective consequences of winter pasture contamination by sheep infected with 6 species of trichostrongylid gastro-intestinal nematode (GIN) at Armidale in the New England region of NSW. Ten helminthologically inert pasture plots were contaminated using ‘donor’ sheep harbouring artificial infections of Haemonchus contortus, Trichostrongylus colubriformis, Trichostrongylus vitrinus, Trichostrongylus axei, Nematodirus spathiger and Teladorsagia circumcincta. A single plot was contaminated in March to serve as a positive control and three plots in each of the winter months of June, July or August of 2007. Weekly assessments of 24 h faecal output and worm egg count of all donor sheep, combined with differentiation of larval cultures enabled calculation of total egg deposition per plot for each GIN species for each month of contamination. All plots were provided with supplemental spray irrigation sufficient to remove desiccation as a cause of non-development. The infective consequence of each monthly contamination was assessed by grazing each plot with two tracer sheep for the last 14 days of each month following contamination until a final grazing in November. Translation for each GIN species was expressed as the percentage of eggs deposited translating to worms counted in tracer sheep. The GIN parasites fell into two distinct groups differing greatly in translational success. Translation of egg to establishment in the tracer host was ineffective for H. contortus, T. axei and T. colubriformis but effective for T. vitrinus, T. circumcincta and N. spathiger. Overall mean total translation for each of these species throughout the experiment was respectively 0.00%, 0.00%, 0.00%, 0.34%, 0.45% and 0.48%. We conclude that winter contamination of pastures in this region with eggs of the latter 3 species is capable of impacting on the health of sheep subsequently grazing these pastures. Where H. contortus and T. colubriformis predominate, paddocks selected for spring lambing may be grazed safely over the winter months without contributing significantly to pasture contamination. These findings are particularly relevant to the preparation of clean spring lambing paddocks in this region using grazing management.

An area-wide model approach for the management of a disease vector planthopper in an extensive agricultural system

The “Mal de Río Cuarto” disease in maize is a viral disease caused by a reovirus (MRCV) and transmitted by the delphacid planthopper Delphacodes kuscheli Fennah in a persistent manner. Although the disease is endemic in only one provincial department, when regional outbreaks occur the losses in maize production are very significant. Actively dispersing D. kuscheli individuals were collected from 15 sampling sites during the 1999 and 2000 spring seasons using sticky traps placed at 6 m above ground level, designed to detect flying individuals. Insect host patches were surveyed using Landsat 5 TM images for the periods studied. Two critical landscape metrics, total class area and mean proximity index, were calculated using FRAGSTATS 3.3 on the winter pasture satellite images. A multiple regression model showed the relationship between host patch area, mean proximity index and D. kuscheli abundance to be highly significant ( R 2 = 0.96, r = 0.98, P < 0.0001). Spatial simulations of different host areas and different interpatch separations were created in order to test the effect of these metrics on the abundance of the dispersing individuals. The estimate of the insect's abundance showed that, although patch size is very important in determining mean insect abundance in an area, the separation of these patches is crucial to establish the effect of host patch area on the abundance of dispersing individuals. Until now, disease management consisted in modifying sowing dates in order to avoid maximum D. kuscheli abundances and thus minimize risk of Mal de Río Cuarto Disease. Our results show that a rational area-wide management of host patches can keep populations of the vector at a very low level, diminishing the risk of a regional outbreak.

Hypertension and insulin resistance in a mixed-breed population of ponies predisposed to laminitis

To determine the metabolic phenotype of a group of laminitis-prone ponies when at pasture in summer, compared with when at pasture in winter. 40 ponies of various breeds predisposed to recurrent pasture-associated laminitis and 40 unaffected control ponies. Body condition score and size of the crest of the neck were assessed, blood samples obtained, and blood pressure measured by use of an indirect oscillometric technique, while ponies were kept on winter pasture (last week of November or beginning of December) and again on summer pasture (June). Serum insulin concentration and plasma glucose, triglyceride, uric acid, and ACTH concentrations were measured. Insulin sensitivity was calculated with proxies derived from basal serum insulin and plasma glucose concentrations. No significant differences were apparent between ponies predisposed to laminitis and control ponies during winter. However, in June, laminitis-prone ponies had increased serum insulin concentration and plasma triglyceride and uric acid concentrations, compared with control ponies. Also, laminitis-prone ponies were relatively insulin resistant, compared with control ponies. Mean blood pressure was significantly higher during summer in laminitis-prone ponies (median [interquartile range], 89.6 mm Hg [78.3 to 96.9 mm Hg]), compared with control ponies (76.8 mm Hg [69.4 to 85.2 mm Hg]). Summer pastures appear to induce metabolic responses in some ponies, leading to expression of the prelaminitic phenotype, which includes hypertension as well as insulin resistance. Signs of this metabolic syndrome may not be apparent in affected ponies during periods of grazing winter pasture. Understanding this syndrome may enable improved countermeasures to be devised to prevent laminitis.

Phosphorus, nitrogen and sediment losses from irrigated cropland and pasture grazed by cattle and sheep

Grazing forage crops during winter can lead to soil physical damage and contaminant losses especially on Pallic soils prone to compaction and structural degradation. A site in North Otago (Timaru silt loam) with 2 years sheep and cattle grazing on winter forage crops and pasture was used to measure phosphorus (P) and nitrogen (N) losses in sub-surface (leachate from shallow lysimeters) flow and P losses in overland flow. Keywords: phosphorus, nitrogen, sediment, irrigation, overland flow, treading, grazing, pasture, crop land

New Zealand made controlled release coated urea increases winter growth rates of Italian ryegrass with lower N leaching than uncoated urea

In a field trial the application of 5 and 7% polyurethane coated controlled release urea, 10% dicyanodiamide coated urea and three x 50 split urea (SU) applications at 150 kg N/ha (150 N) increased winter pasture dry matter (DM) production of Italian ryegrass over the June-September period by between 1666 to 2240 kg DM/ha. These treatments also reduced nitrate leaching losses from 6.8 to 1 kg N/ha compared to urea (U). Keywords: controlled release urea, nitrogen utilisation, pasture, ryegrass

Terpenoids and benzenoids in La Serena cheese made at different seasons of the year with a Cynara cardunculus extract as coagulant

The objective was to determine the influence of the season of manufacture and the ripening time on the volatile terpenoids and benzenoids of La Serena cheese made in summer, winter and spring, using a plant coagulant. Ewes were fed with formulated feed in summer, grazing on natural pastures in winter and spring. Most terpenoids and benzenoids present in cheese were observed in the formulated feed (mainly terpenes), and in the Cynara cardunculus extract (mainly benzenoids). The enantiomeric α(+)⧸ α(−)−pinene ratio changed during ripening. γ-Curcumene, α-humulene, ethyl benzene and propyl benzene and all xylene isomers decreased, while α-terpineol, verbenone, benzyl alcohol, 2-phenyl-ethanol, benzoic acid methyl ester, and the phenolic compounds increased significantly during ripening. Safranal, geranyl acetone, γ-curcumene and α-curcumene were more abundant in spring than in winter cheeses. Alkyl benzenes and other benzenoids were significantly more abundant in summer than in winter or spring cheeses.

Transhumant Pastoralism in Yak Production in the Lower Mustang District of Nepal

Abstract There are thirty yak herd owners, all men and mainly Thakalis, between Jomsom and Lete in Lower Mustang. Transhumance is used in herding yaks, which migrate seasonally between winter pastures at about 3,000-4,000 metres and summer pastures at about 4,000-5,000 metres above sea level. Absentee herd ownership, in which shepherds (usually members of a non-Thakali ethnic group) herd only yaks and do not own any animals themselves, is common. Yaks are raised primarily for meat and milk, though substantial income is realized from selling blood during two blood-drinking ceremonies and from selling yaks as pack animals. Milk is used for products such as butter/ghee and a dry, hard curd cheese (chhurpi), which are mainly sold but also used for home consumption and for making 'salty butter tea'. Yak wool has little commercial value today but is used to make rope and tents. Yak owner estimations of how much of their income is derived from their herds range widely between 10 percent and 90 percent, but average about 50 percent. Additional income is made from the sale of seasonal crops, in particular apples, potatoes, maize, millet and barley that are produced on the owners' land. Owners also raise chickens, cows, buffalo, oxen, horses and goats. Two of the herd owners owned hotels that were run by their families. In this study, annual earnings from yaks totalled approximately Nepalese Rupees (N.Rs) 72,780 and total income for the herd owner was about N.Rs 145,560 (U.S. $2,079). We concluded that for these herd owners, yak raising is not a subsistence economic activity but rather part of a market economy based on speculative investments and accumulation. Moreover, yak production is a very high-risk enterprise as disasters can decimate large proportions of a herd quickly.

Atributos físicos do solo em sistema de integração lavoura-pecuária sob plantio direto

A compactação do solo é um dos principais fatores responsáveis pela queda da produtividade das culturas agrícolas. Por isso, o impacto causado pelo pisoteio bovino sobre o solo e os conseqüentes reflexos nos atributos físicos densidade do solo, porosidade do solo, resistência mecânica à penetração e infiltração de água no solo, em área manejada sob sistema integração lavoura-pecuária, foram investigados em experimento de campo, no município de Jari, na região do Planalto Médio do Rio Grande do Sul, Brasil. Foram avaliados três sistemas de manejo da pastagem de inverno (aveia-preta, Avena strigosa Schreber + azevém, Lolium multiflorum Lam.), caracterizados pela freqüência de pastejo: (1) Sem Pastejo (SP), (2) Pastejo a cada 28 dias (P28) e (3) Pastejo a cada 14 dias (P14). Além disso, foi avaliada a influência da cultura de verão, soja [Glycine max (L.) Merr.] ou milho (Zea mays L.), em rotação com as pastagens de inverno, em amenizar ou agravar a ação compactadora do pisoteio bovino. A compactação do solo, avaliada pela sua densidade, concentrou-se na camada de 0-0,05 m de profundidade, porém houve redução de sua macroporosidade até a camada de 0,10-0,15 m, no sistema com a maior freqüência de pastejo (P14). A resistência mecânica do solo à penetração atingiu valores de 2,61 e 2,49 MPa nos tratamentos P14 e P28, respectivamente, nas profundidades de 0,05 e 0,08 m, enquanto as áreas que não foram pastejadas mantiveram valores inferiores a 1,66 MPa. A taxa de infiltração de água no solo foi alterada significativamente pelo pisoteio bovino e pela cultura de verão antecedente. Com a cultura de milho, o solo mostrou-se menos sensível ao pisoteio bovino, ao passo que com a cultura de soja na maior freqüência de pastejo (P14) a taxa de infiltração de água no solo foi reduzida. A cultura de soja proporcionou os maiores valores de macroporosidade nas camadas avaliadas e, quando conjugada à menor freqüência de pastejo (P28) ou à ausência de pastejo (SP), observaram-se as maiores taxas de infiltração de água no solo.

Spatiotemporal Variations in Growing Season Exchanges of CO2, H2O, and Sensible Heat in Agricultural Fields of the Southern Great Plains

Abstract Climate, vegetation cover, and management create finescale heterogeneity in unirrigated agricultural regions, with important but not well-quantified consequences for spatial and temporal variations in surface CO2, water, and heat fluxes. Eddy covariance fluxes were measured in seven agricultural fields—comprising winter wheat, pasture, and sorghum—in the U.S. Southern Great Plains (SGP) during the 2001–03 growing seasons. Land cover was the dominant source of variation in surface fluxes, with 50%–100% differences between fields planted in winter–spring versus fields planted in summer. Interannual variation was driven mainly by precipitation, which varied more than twofold between years. Peak aboveground biomass and growing season net ecosystem exchange (NEE) of CO2 increased in rough proportion to precipitation. Based on a partitioning of gross fluxes with a regression model, ecosystem respiration increased linearly with gross primary production, but with an offset that increased near the time of seed production. Because the regression model was designed for well-watered periods, it successfully retrieved NEE and ecosystem parameters during the peak growing season and identified periods of moisture limitation during the summer. In summary, the effects of crop type, land management, and water limitation on carbon, water, and energy fluxes were large. Capturing the controlling factors in landscape-scale models will be necessary to estimate the ecological feedbacks to climate and other environmental impacts associated with changing human needs for agricultural production of food, fiber, and energy.

Fixação biológica de nitrogênio por plantas de trevo (Trifolium spp) em sistema de integração lavoura-pecuária no Sul do Brasil

Este trabalho foi realizado com o objetivo de avaliar o efeito da inclusão de plantas de trevo (Trifolium spp) sob pastejo em sistema de integração lavoura-pecuária sobre a quantidade de N fixada, a produtividade, os componentes de rendimento da cultura de milho e os teores de nitrato no solo. O delineamento utilizado foi de blocos ao acaso, com três repetições, em que as parcelas foram constituídas dos resíduos de espécie forrageira (trevo e aveia) e as subparcelas, das quatro doses de N em cobertura (0; 60; 120; e 240 kg/ha). Durante o período de cultivo do milho (2004/2005), as parcelas contendo resíduo de trevo apresentaram maiores de teores de N-nitrato na profundidade de 0-5 cm em comparação àquelas cultivadas anteriormente com aveia, indicando que a cultura de milho encontraria praticamente todo o suprimento de nitrogênio, em decorrência do cultivo anterior de trevos pastejados. Não foram observados indícios de lixiviação de nitratos provocados pelos resíduos de leguminosas até a camada de 20 cm de profundidade do solo. No segundo ano de experimento, plantas de trevo pastejadas contribuíram, no mínimo, com suprimento de N de 90 kg/ha, como resultado da fixação biológica para a cultura de milho. No entanto, plantas de milho cultivadas sobre resíduos de aveia apresentaram máxima produtividade de grãos com aplicação de 180 kg/ha de N.

Evaluation of TRICAL-336 Triticale, Maton Rye and Kentucky-31 Fescue as Winter Pasture for Meat Goats

ABSTRACT Because of their cold tolerance and double-cropping potential, small grains such as triticale (× Triticosecale Wittmack) and rye (Secale cereale) can play an important role in sustainable agriculture in Tennessee. A grazing trial was conducted to evaluate TRICAL-336 (triticale), Maton (rye) and Kentucky-31 fescue (control) for meat goats. Maton and TRICAL-336 were 78 and 74% higher in crude protein, 33 and 44% lower in acid-detergent fiber, and 49 and 51% lower in neutral-detergent fiber, respectively, than Kentucky-31. Net energy, total digestible nutrient, relative feed value, Ca, Mg, K and P contents were also significantly higher (P < 0.01) for Maton and TRICAL-336. Average daily gain and live weight gain per ha of does grazing Maton (74.0 g d−1 and 12.38 kg ha−1) and TRICAL-336 (78.9 g d−1 and 11.77 kg ha−1, respectively) were significantly higher (P < 0.05) than that of Kentucky-31 does which lost weight (−19.4 g d−1 and −2.6 kg ha−1, respectively) during the same period. Boneless major retail cut yield was 23 and 37% higher in favor of Maton and TRICAL-336, respectively, while boneless shoulder, boneless leg, loin and rack weight were 30, 35, 69 and 37% higher for TRICAL-336 and 17, 19, 22 and 61% higher, respectively, for Maton than for Kentucky-31. Hot carcass weights and chilled carcass weights were higher for Maton by 28 and 20% and for TRICAL-336 by 32 and 30%, respectively, than Kentucky-31. Slaughter weight, height to the cross, carcass length, kidney, pelvic and heart fat, thoracic circumference, blood concentration of creatine kinase, glucose, albumin, globulin, blood urea nitrogen, Ca, Na, K, monocyte, red blood cell, hematocrit and hemoglobin were significantly higher (P < 0.05) for TRICAL-336 and Maton.

Feeding behaviour of yaks on spring, transitional, summer and winter pasture in the alpine region of the Qinghai–Tibetan plateau

Of the present estimated world population of 14.2 million yaks, approximately 13.3 million occur within Chinese territories (Food and Agriculture Organization of the United Nations, 2003). Although there is an extensive bibliography covering the species, few studies have been conducted in the area of foraging behaviour. The present study was conducted at pasture during the spring, transitional, summer and winter seasons to determine the daily temporal patterns of grazing and ruminating behaviour by yaks. During each study period, two 24 h recordings were undertaken with each of six mature dairy yaks. One study period was conducted on each of the transitional, summer and winter pastures, whereas, due to the considerable changes occurring in the morphology of the spring pasture, three separate studies were completed during March, April and May. During the second of these studies (April), the effect of level of concentrate supplementation on grazing and ruminating behaviour was also examined. Behaviour recordings were made using solid-state behaviour recorders. Short-term intake rates (IR, g min −1) were calculated by weighing yaks before and after approximately 1 h of grazing, retaining the faeces and urine excreted and applying a correction for insensible weight loss. Yaks spent less time grazing during the dry season (the early period on the spring pasture) compared with the later green swards (the later period on the spring pasture, the transitional pasture and the summer pasture) ( P < 0.05). When the forage quality improved, but there was still insufficient mass (the later period on the spring pasture), the yaks extended their grazing time at the expense of other activities. During the early periods on the spring pasture, the short-term IR by yaks was up to 53 g DM min −1, significantly higher than at other times ( P < 0.05). The level of concentrate offered had little or no effect on grazing or ruminating time. The total eating time of the yaks offered 0.5 or 1.0 kg concentrate was 2.9 and 4.5 h day −1, respectively, significantly lower than unsupplemented yaks (6.8 h) ( P < 0.05). In general, yaks can regulate their foraging behaviour according to the changes of sward conditions in order to achieve optimal grazing strategies.