Dairy Area Research Articles

酪農家，川へ入る―住民と NGO の協働による河川環境再生プロジェクト

酪農家，川へ入る―住民と NGO の協働による河川環境再生プロジェクト

Mycotoxins in small grains and maize: Old problems, new challenges

This paper reviews the challenges relating to chronic contamination of small grains and maize with deoxynivalenol and related compounds, fumonisin and the use of ensiled cereals in cool dairy areas. Uncertainties in the tolerable daily intakes for deoxynivalenol and fumonisin are discussed as they have the potential to affect current regulatory limits. In addition, climate change is resulting in more extreme rainfall and drought events which favour formation of deoxynivalenol and fumonisin, respectively. The development and refinement of models for predicting mycotoxin accumulation from weather data will become an essential tool for managing these events. Such models are also important for providing timely food aid to developing countries, which experience increased occurrence of acute toxicities, especially in children. Chronic contamination of silage in some areas with some Penicillium toxins deserves more attention in terms of their economic effects and possible implications for the purity of milk.

Effect of whole cottonseed supplementation on energy and nitrogen partitioning and rumen function in dairy cattle on a forage and cereal grain diet

The experimental objective was to determine the effect of adding whole cottonseed (WCS) to a forage and cereal grain diet on the energy and nitrogen balance and rumen function of lactating dairy cattle. Two experiments were carried out, a field experiment and an indoor metabolism experiment. In the field experiment, 50 lactating cows ~200 days in milk were randomly allocated to one of two groups (control or WCS). Cows were offered lucerne hay (morning) and ryegrass-based pasture silage (afternoon) in one group for 5 weeks. The hay and silage were placed on the ground in a bare paddock. Cows in each group were also individually offered cracked grain in a feed trough at 3 kg dry matter (DM)/cow.day at milking times. In addition, at milking times, cows in the WCS group were individually offered 2.7 kg DM/cow.day of WCS with their grain supplement. Samples of rumen fluid were collected from each fistula, ~4 h after grain feeding in the morning, of eight cows (four per group) on 1 day in each of the 5 weeks of treatment. In the metabolism experiment, immediately after the 5 weeks of feeding, 12 lactating cows, six from each treatment from the field experiment, were randomly selected and individually housed in metabolism stalls and fed the same diets for a 6-day energy and nitrogen balance study. Cows were fed at milking times (0700 and 1530 hours) and all feed offered and refused was weighed daily. All cows were offered 5.6 kg DM/cow.day of pasture silage, 4 kg DM/cow.day of lucerne hay and 3 kg DM/cow.day of cereal grain. In addition, cows in the WCS treatment group were offered 2.7 kg DM/cow.day of WCS with their grain supplement. In the metabolism study, adding WCS to the diet resulted in a greater energy intake, but there was no depression in energy digestibility. Whole cottonseed also increased nitrogen intake and nitrogen digestibility of the diet was increased from 62 to 75%, but the proportion of nitrogen in milk remained the same with a greater proportion of nitrogen appearing in body tissue. In the field experiment, supplementation with WCS did not alter rumen fluid ammonia-N or volatile fatty acid concentrations. Adding WCS did not affect three of the main classes of protozoa, based on size, within the two major orders of ciliate protozoa. The WCS did, however, reduce the levels of entodiniomorphs >200 µm diameter and holotrichs < 200 µm diameter, but these only account for a small number of the total protozoa present. Supplementation of a forage and grain-based diet with WCS improved the energy and protein content of the diet without any negative effects on rumen digestion and with a similar proportion of dietary energy and nitrogen appearing in milk. Over the summer period in winter-rainfall dairying areas in south-east Australia when pasture availability is limited and the diet is mainly comprised of forage and cereal grain fed at a level that is energy-limiting for maximum production, WCS can be and is used to supplement the diet to improve milk yield and profitability.

ESTUDO DA EFICÁCIA “IN VITRO” DO AMITRAZ E DA DELTAMETRINA COMO CARRAPATICIDA NO CONTROLE DE Boophilus microplus (CANESTRINI, 1887) NA BACIA LEITEIRA DA MICRORREGIÃO DE GOIÂNIA - GOIÁS

The efficacy of amitraz and deltamethrin as acaricides against Boophilus microplus (Canestrini, 1887) was evaluated through an in vitro immersion test using engorged female ticks collected in the dairy area of the microrregion of Goiânia, State of Goias. The effectiveness of the experimental compounds, on concentrations of 250 ppm, was determined by the effect as measured in percentages of inhibited reproduction (%INR) after treatments of the ticks with liquid formulations. The results were: amitraz showed the best efficacy with a percentage of inhibited reproduction (%ITR) of 97.11%; for deltamethrin such value was 70.86%, which was considered very low to be used as an acaricide. KEY-WORDS: Boophilus microplus ; acaricides; amidines; pyrethroids; cattle.

A comparison of seroprevalence and risk factors for Theileria parva and T. mutans in smallholder dairy cattle in the Tanga and Iringa regions of Tanzania

A cross sectional serological survey was carried out in two geographical small-scale dairying areas of Tanzania to determine the distribution and prevalence and to quantify risk factors for Theileria parva and T. mutans during the period January to April 1999. The prevalence of serum antibodies to these two Theileria parasites was determined using an indirect enzyme-linked immunosorbent assay (ELISA) technique. The results suggest that the parasites are widely distributed through out the two study sites and seroprevalence of 23% and 48% for T. parva were obtained for Tanga and Iringa regions, respectively. Seroprevalence of T. mutans ranged from 17% in the Tanga region to 40% in the Iringa region. Farm and animal data were collected and analysed by multiple logistic regression models to explore the risk factors associated with seroprevalence to T. parva and T. mutans pathogens. In both regions, seroprevalence for the two Theileria spp. pathogens increased significantly with age. Pasture grazed animals were more likely to be seropositive than those that were zero-grazed. Among individual animal characteristics, seropositivity was higher in cash-bought and charity gifted animals compared to cattle obtained using a formal credit agreement. Further studies on the relative role of risk factors for theileriosis found in this study may assist in the development of an effective control package.

Effect of neosporosis on productive and reproductive performance of dairy cattle in Costa Rica

A cross-sectional study was conducted to assess the effect of neosporosis on productive and reproductive parameters in dairy cows. Cows ( n = 2743) from 94 farms located in the most important dairy areas in Costa Rica were used in the study. The size of the herds ranged from 32 to 379 females (mean = 110, median = 125). An indirect ELISA was used to determine the serostatus of the cows towards Neospora caninum. The effect of neosporosis on milk production was analysed by a mixed linear model. In addition, the effects on calving interval (days) and calving to conception interval (days) were analysed by survival analysis. The risk of abortion in relation to N. caninum serostatus was assessed by logistic regression, with herd as a random effect. Overall, 1185 of 2743 cows (43.3%) were seropositive for Neospora. Eighty-nine of 94 (94.7%) farms were classified as Neospora-seropositive. It was estimated that cows seronegative to Neospora produced an additional 84.7 L of milk ( P = 0.6). Serostatus did not have a significant effect on the length of the calving interval in the Cox proportional hazard survival analysis (Hazard ratio = 1.2, 95% CI: 0.9, 1.4). The logistic regression model had a weak positive association between serostatus and abortion (OR 1.7, 95% CI: 0.8, 3.9), but did not show a strong association between serostatus and the number of services per conception (OR = 0.95, 95% CI: 0.7, 1.3). In conclusion, there were no significant effects of Neospora serostatus on production and reproductive performance in this study.

Avaliação de híbridos comerciais de milho para utilização como silagem na Região Sul do Brasil

As temperaturas baixas e geadas que ocorrem na Região Sul, durante a estação fria, determinam uma diminuição em quantidade e qualidade das pastagens. Para suprir as necessidades dos animais nos períodos de escassez de forragem, a silagem de milho tem sido muito utilizada. Tem sido apontada a existência de diferenças entre genótipos de milho quanto à produção e qualidade da silagem obtida. O objetivo deste trabalho foi identificar o potencial de híbridos comerciais de milho para produção de silagem na Região Sul do Brasil. Vinte e um híbridos foram testados em sete locais (Cascavel, Chapecó, Ijuí, Lages, Ponta Grossa, Teutônia e Urussanga), em delineamento de blocos casualizados com três repetições. Foram avaliados a produção de matéria seca e o potencial de produção de leite, estimado com base em análises bromatológicas. Houve diferença significativa entre híbridos quanto aos caracteres avaliados. As médias dos híbridos variaram de 11,27 a 14,83t ha-1 para produção de matéria seca e de 4,868 a 7,207kg ha-1 para produção de leite. Os efeitos de local e da interação de híbrido por local também foram importantes na determinação dos caracteres. As médias dos locais para produção de matéria seca variaram de 8,69 a 19,22t ha-1 e para produção de leite de 3,845 a 8,515kg ha-1, tendo Cascavel apresentado os valores mais altos. Existe variabilidade entre os materiais indicados para cultivo na Região Sul do Brasil quanto ao potencial de utilização na forma de silagem. Entretanto, como a classificação dos híbridos é fortemente influenciada pela interação de genótipos por ambientes, é necessário que as recomendações sejam regionalizadas.

Cross-sectional estimation of <i>Babesia bovis<i/> antibody prevalence in cattle in two contrasting dairying areas in Tanzania

The crude prevalence of antibodies to Babesia bovis infection in cattle was estimated by serology using indirect ELISA during the period January to April, 1999. Sera were obtained from 1,395 dairy cattle (of all ages, sexes and breeds) on smallholder farms, the majority being kept under a zero grazing regime. The crude prevalence of antibodies to Babesia bovis was 6 % for Tanga and 12 % for Iringa. The forces of infection based on the age sero-prevalence profile, were estimated at six for Iringa and four for Tanga per 100 cattle years-risk, respectively. Using random effect logistic regression as the analytical method, the factors (variables) of age, source of animals and geographic location were hypothesised to be associated with sero-positivity of Babesia bovis in the two regions.

Distinguishing sources of groundwater nitrate by 1H NMR of dissolved organic matter

Dissolved organic matter (DOM) originating from a certain source usually carries characteristic marks in its molecular structures that can be recognized by spectroscopic analysis. Sources of water-borne contaminants, such as nitrate, can be identified by recognition of the characteristics of DOM entrained in the water. In this study, DOM in groundwaters sampled from a dairy/crop production area (Chino Basin, CA) was analyzed by 1H nuclear magnetic resonance ( 1H NMR). Results showed that DOM derived from natural soil organic matter has a characteristic resonance at a chemical shift region of 4.0–4.3 ppm, while DOM derived from dairy wastes has a characteristic resonance at a lower chemical shift region of 3.2–3.6 ppm. These signature resonances were then used to distinguish the origins of nitrate in the groundwater. It was found that disposal of dairy wastes on croplands is the primary source of nitrate contamination in groundwater underlying the Chino Basin dairy area.

Eradication of bovine brucellosis in the 10th Region de Los Lagos, Chile

The process of Bovine Brucellosis Eradication that began in 1996 in the 10th Region de Los Lagos of Chile will be reviewed. The region comprises the most important dairy area of the country and it has the largest concentration of brucellosis infected herds. Based on the information gathered by an epidemiological surveillance system, the results of the eradication process for the years 1996 till 2001 are presented as rates of Milk Ring Test (MRT) positive dairies, rates of brucellosis reactors (bovines) in livestock markets and slaughterhouses, and the annual incidence and prevalence of brucellosis infected herds. During the period the rates of positive dairies, bovine reactors in livestock markets and slaughterhouses, and the annual incidence and prevalence of infected herds have experienced a decrease, while the rate of bovine reactors in slaughterhouses has remained stable. Data on the preventive measures taken, such as vaccination of female bovines and Certification of Brucellosis Free Herds, are also shown. The surveillance system has allowed the detection of infected herds, while the measures of prevention and cleaning of infected herds have allowed a reduction in the incidence and prevalence of the infection by Brucella abortus.

Evolution of nitrogen species air pollutants along trajectories crossing the Los Angeles area.

Ambient aerosol sampling was conducted in Diamond Bar, Mira Loma, and Riverside, CA, to observe at close range the effects of ammonia emissions on air quality. These sites are located upwind,within, and downwind, respectively, of the Chino dairy area, the largest single source of ammonia emissions in the Los Angeles area. Inertial impactors and bulk filter samplers provided 4-7-h measurements of aerosol chemical composition and size distribution. Daily average fine particle mass concentrations were in the range 22.4-143.0 microg m(-3). On some days the fine particulate matter concentrations were more than two times greater than the proposed 24-h Federal standard of 65 microg m(-3). Ammonium nitrate was the largest component of fine particle mass at all three sites; 24-h average fine particulate ammonium plus nitrate concentrations ranged from 11.7 to 75.4 microg m(-3). A single air mass was studied as it passed the Diamond Bar air monitoring site in the morning and stagnated near Mira Loma in the evening of the same day. Between these two sites NO was oxidized to NO2, and the ammonia concentration increased by a factor of 5. A second air parcel trajectory, which stagnated near Mira Loma during the early morning and passed near the Riverside site approximately 24 h later, showed a decrease in ammonia concentration over time that is consistent with dilution as the air mass moved downwind from the source of ammonia in the dairy area. Particulate NH4NO3 concentration in that air parcel remained approximately constant over time, consistent with a continued excess of NH3 relative to HNO3 downwind of the dairy area.

Factors associated with Neospora caninum serostatus in cattle of 20 specialised Costa Rican dairy herds

Twenty-five specialised Costa Rican dairy farms (located in the Poás area) were used to determine neosporosis seroprevalence and the association of seropositivity with environmental and management factors. The farms involved were selected intentionally and all of them use VAMPP 5.1 (Veterinary Automated Management and Production Control Programme) as management-information system. Holstein–Friesian, Jersey and crosses between them were the most-frequent breeds in these herds. The number of females per farm varied from 41 to 296. Our cross-sectional study had two phases. In the first phase, we determined the presence or absence of seropositivity at herd level. For the second phase, all females in 20 seropositive farms were bled. Serum samples were tested for antibodies to Neospora caninum using an indirect enzyme-linked immunosorbent assay (ELISA). A questionnaire with factors mentioned in the literature was administered to the farmers. Logistic regression (LR with herd as random effect) was used to assess the relationships of the serostatus at the individual level with characteristics of the cows and environmental factors. In the first phase all herds had >20% seropositive females; therefore, all herds were eligible for the second phase. In the second phase, the overall prevalence was 39.7% (1191/3002), and within-herd prevalences were between 25.0 and 70.5%. Age 3–6 years, parity ≤2 of the dam of the cow, Jersey breed and lack of purposive sampling to diagnose abortive infectious disease were associated with positive serostatus; other management and environmental factors did not show significant associations. The lack of association between management and environmental factors with serostatus might be because all farms were exposed to a considerable number of potential factors. That all herds of this study were seropositive for neosporosis and the within-herd prevalence was considerable raises questions about how far the infection is spread in other dairy areas of Costa Rica.

Characterization of lactococci isolated from milk produced in the Camembert region of Normandy.

Thirty-eight Lactococcus strains, isolated from raw milk produced in two dairy areas in Normandy, were identified at the phenotypic level. Only Lactococcus lactis strains with the lactis phenotype were found in the milk samples. Most strains fermented lactose (97%) and showed proteinase activity (76%). Isolates were characterized by RAPD technique and rRNA gene restriction analysis. More L. lactis strains with the lactis genotype were found in the first area, while L. lactis strains with the cremoris genotype predominated in the second area. RAPD was more efficient than rRNA gene restriction analysis in differentiating between strains with the subsp. lactis genotype. For L. lactis with the subsp. cremoris genotype, the second method gave a better result but there was poor discrimination between strains. Plasmid profiles were determined. Patterns ranged in size from 1.3 to 16.5 kbp, and 29 different profiles were found. Six groups of strains were determined, five of which were specific for the area of origin. It is suggested that the region of manufacture could influence organoleptic properties of cheeses because of different Lactococcus strains in the raw milk used for cheese making.

Pasture response to fertiliser inputs under dairy grazing

Conversion of sheep and beef farms into dairy units has resulted in research on appropriate fertiliser rates and pasture species to achieve maximum productivity in minimum time. An onfarm trial involving five different mixtures of pasture species (based on fescue, prairie grass, an improved mixture, farmer mixture or original pasture), three rates of nitrogen as urea (0, 50 or 100 kg/ha of N applied half in March and half in August) and four rates of superphosphate (0, 250, 500 or 1000 kg/ha applied annually in March) was established in Canterbury on a Waimakariri sandy silt loam with border-dyke irrigation and an Olsen P of 5 pg/ml. The trial was grazed by dairy cattle as part of the general rotation; plots were not fenced individually. Pasture growth rates were measured pre- and post-grazing using a calibrated pasture probe. Botanical dissections ,were made seasonally and soil samples were taken annually. Pasture dry matter production was greatest from the prairie grass, "improved" mixture and the original pasture, involved often contain a high proportion of annual and perennial, low-producing species. Grass species, nutrient status and management have been identified as the limiting factors in dairy conversion (Kleyngeld & Kleyngeld 1992). Ryegrass and white clover are still the most common species used in pasture renovation (Maloney 1991). However, short-rotation ryegrasses are favoured by some dairy farmers, and in new dairying areas such as Canterbury, optimally producing species may differ from those used in the more traditional North Island dairying areas (Charlton & Belgrave 1992). Nitrogen (N) is recognised as a strategic tool for increasing grass production in winter-spring in summerdry areas (Thomsoneta/. 1991) as well as for extending the milking season for factory supply herds in Southland (Kleyngeld & Kleyngeld 1992). High rates of nitrogen (217 and 324 kg/ha per year) have been found to increase annual net herbage accumulation by 23 and 27%, respectively, in the Waikato, but clover content declined significantly (Harrisetaf. 1994). Maintenance fertiliser requirements have been related to desired stocking rate in the past, based on animal production system and soil type (Computerised Fertiliser Advisory System (CFAS), reaching 13 000,ll 000 and 16 000 kg/ha in years Cornforth & Sinclair 1984). Recently responses in milk one, two and three, respectively; production from yield have been recorded to very high rates (100 kg/ha- IT the fescue increased with time; the 'farmer' mix performed poorly. Nitrogen at 50 kg/ha was generally sufficient to produce maximum yield increases. Increasing superphosphate increased production; this effect decreased with time. Change in Olsen P reflected superphosphate inputs and after three years of differential superphosphate application the Olsen P status was 8, 14, 27 or 42 (corresponding to 0, 250, 500 or 1000 kg/ha superphosphate). Keywords: Bromus wildenowii, dairy conversion, dry matter production Festuca arundinacea, Loliumperenne, nitrogen, Olsen P, superphosphate

Genetic Parameters for Yield and Reproductive Traits of Holstein and Jersey Cattle in Florida

Records of yield and reproduction from 4293 Holstein and 2143 Jersey first lactation cows from eight Holstein and six Jersey herds were utilized to evaluate genetic parameters for Florida, a subtropical environment. Statistical analyses were by derivative-free REML with the animal model. Genetic variances were based on variation in estimated breeding values of individual cows. Heritabilities were .27 to .43 for yields (6 estimates), .38 to .51 for constituent percentages (4 estimates), and .025 to .056 for reproduction (6 estimates), which were similar to estimates for temperate areas from similar procedures. Also, correlations of breeding values between yields were high and between yields and reproduction were low and generally antagonistic. Correlated responses in calving interval from selection for yield, with selection intensities of 1.0 to 1.5, would be expected to lead to increases of 1.0 to 5.2 d per generation (12 estimates). Thus, estimates of genetic parameters and correlated responses in this subtropical environment did not differ appreciably from those that occur in temperate dairy areas.

Aspects of heifer management which limit productivity on dairy farms in Western Australia: a survey

In 1989, a survey of 53 producers from the major dairy areas of the south-west of Western Australia was conducted to determine current management practices for dairy heifers and to identify of areas of heifer management which could be improved to increase overall farm productivity. Total farm size averaged 220 ha, with an average market milk quota of 699 L/day (50% of total milk produced). One-third of producers described their farm activity as dairying only. Some 116 calves were born per farm, with a year-round calving distribution. Calves were fed 5.4 L whole milk/day, with an average age at weaning of 13 weeks (range 5-26 weeks). Mortality recorded to 3 months of age was 4% and the most important health problem associated with calf rearing was scours. Of those properties with a health problem, 25% used antibiotics on a regular basis. All producers provided supplementary feed pre-weaning. In the period between weaning and mating, more than half the producers ran heifers on paddocks 3-80 km distant from the main farm, with hay the most common form of supplementary feed. Most dairy heifers were naturally mated to Hereford, Friesian, or Angus sires; hence, few heifers from first calvers were kept as dairy replacements. Average age at first calving was reported to be 30 months, with 1 in 9 heifers culled post-calving, generally for low milk production. The survey highlighted several aspects of heifer management with the potential to improve overall productivity of dairy farms in Western Australia. They include earlier weaning, strategic use of antibiotics to prevent the development of antibiotic resistance, greater use of artificial insemination, and a reduction in age at first calving.

Prevalence of parasite eggs and cysts in faeces from dairy cows in Colombia.

When 1,711 bovine faecal samples from 113 farms in eight dairy areas of Colombia were examined for the presence of helminth eggs Fasciola hepatica eggs were found in the faeces from 60% of the farms and samples from animals kept above 2,000 m. Strongyle eggs were found in faeces from 82% of the farms and in 18% of the samples.

Genetic and Environmental Effects Upon Reproductive Performance of Holstein Crossbreds in the Sudan

Data from a herd near Khartoum for 1955 to 1977 were evaluated. Climate was semidesert with most rainfall (151 of 165mm) in July through September. Mean maximum daily temperatures ranged from 30.7 (January) to 41.1°C (May); mean minima were 14.6°C (January) and 26.9°C (June). Original base population (1907) was Butana with additions of Butana, Dairy Shorthorn, Ayrshire, Guernsey, and Holstein. Breed groups and % Holstein were 1, 0 to 25%; 2, 26 to 49%; 3, 50%; 4, 51 to 71%. Numbers and mean performance were gestation length, 2474, 279 d; services per conception, 2403, 2.07; calving interval, 4004, 441 d; days open, 3204, 165 d. Calving intervals (1689) were shorter for Group 3 −25 to −31 d as were postpartum days open (−27 to −31 d), and number of services per conception was lower (.21 to .37). These animals were Holstein by Butana crossbreds, so their superior performance could reflect effects of heterosis. Gestation lengths were affected by month of parturition (January > June, 5.6 d), which also affected services per conception (March > August, .75 services). Over time, not gestation length but services per conception, calving interval, and days open increased. Repeatabilities and heritabilities for these measures were .14 and .07; .07 and 0; .10 and 0; .07 and 0. Phenotypic correlation between days open and calving interval was .99 and with gestation length was −.12. Other phenotypic correlations ranged from −.01 to −.04. Heritability of age at first parturition (888) was .31. Estimates were similar to those from temperature dairy areas.

Projections for British Agriculture

While the 1947 Agriculture Act expresses general support for the farming industry, governments tend to take short-term views, while farmers need longterm indications of government intentions. The White Paper, Food from our own resources, attempts to provide such an indication, which must be viewed in the context of the country's dependence on imported food and of increasing home production from a declining area of agricultural land. Changes in govern? ment policies and the state of the economy suggest a lower rate of transfer of farmland to other uses in the future and the government expects the post-war rise in agricultural production to continue at much the same rate. The pro? jections of output for 1980 also have regional implications within the United Kingdom. Any increase in land under tillage is unlikely to come from eastern England, though there may be exceptions for particular crops. Great improvements in grassland productivity are possible, and an increase in dairy cattle, probably in the main dairying areas, should provide most of the addi? tional beef; but there are likely to be increases in numbers of both sheep and beef cattle on the uplands and upland margins respectively. In the longer run, the role of agriculture may well change in a European context; in the short run, much will depend on farmers' confidence. Since the outbreak of the Second World War, governments have played a major role in British agriculture, in the interests both of safeguarding supplies of homegrown food and of reducing the fluctuations in income which are a characteristic feature of farming. The 1947 Agriculture Act gave formal expression to that in? tention, for its purpose was to promote and maintain 'a stable and efficient agricul? tural industry, capable of producing such part of the nation's food supply and other agricultural produce as in the national interest it is desirable to produce in the United Kingdom and of producing it at minimum prices consistent with proper remuneration and living conditions for farmers and workers in agriculture and an adequate return on capital invested in agriculture'. Since 1947, this aim has been pursued by the publication of an annual review of the agricultural industry and, until the United Kingdom became a member of the European Economic Com?

Diurnal Fluctuation and Movement of Atmospheric Ammonia and Related Gases from Dairies

AbstractSimultaneous 24‐hour air sampling, 0.8 km upwind from the nearest cows in a large dairy area (145,000 cows) and 11.2 km upwind from the dairy area, showed distillable N (mostly NH3) concentrations of 190 and 6 µg/m3, respectively. An average distillable‐N concentration of 540 µg/m3 was measured during a 24‐hour sampling at the downwind corral fence of an isolated 600‐cow dairy. These data indicate significant N loss from dairy waste by NH3 volatilization. The significance of the effects of these higher atmospheric concentrations on NH3 absorption by soils, surface waters, and crops remains to be fully evaluated. Meteorological factors, particularly temperature inversions in the atmosphere and wind, along with proximity to the waste, greatly affected atmospheric concentrations of distillable N. A marked diurnal fluctuation with low concentrations in the afternoon and high concentrations at night were frequently recorded in the large dairy area. Higher nighttime values were related to temperature inversions in the atmosphere. A reversed diurnal pattern with the high afternoon and low nighttime concentrations were recorded at the isolated‐dairy site. Close proximity to the source and a high horizontal flux of distillable N with afternoon winds were important factors in this diurnal pattern. Winds averaging 9.3 km/hour transported distillable N 500 m from the isolated dairy at a height of 1.2 m.