In dairy production, high feed efficiency (FE) is important to reduce feed costs and negative impacts of milk production on the climate and environment, yet little is known about the relationship between FE, eating behaviour and activity. This research communication describes how cows differing in FE, expressed as daily energy corrected milk production per unit of feed intake, differed in eating behaviour and activity. We used data from a study of 253 lactations obtained from 97 Holstein and 91 Jersey cows milked in an automatic milking system. Automated feed troughs recorded feed intake behaviour and cows wore a sensor that recorded activity from 5 to 200 d in milk (DIM). We used a mixed linear model to estimate random solutions for individual cows for traits of steps, lying and eating behaviour and calculated their correlation with FE during four periods (5–35, 36–75, 76–120 and 121–200 DIM). Separate analyses were performed for each breed and period. We found that individual level correlations between FE and behaviour traits were stronger in Jersey than in Holstein cows. Eating rate correlated weakly negatively to FE in Holstein cows and more strongly so in Jersey cows, such that efficient Jerseys were slower eaters. The physical activity of Jersey cows was weakly and negatively correlated to FE, but this was not the case in Holstein cows. We conclude that eating rate was consistently negatively associated with FE throughout lactation for Jersey cows, but not for Holstein cows.

Maternal infection in pregnancy is a known risk factor for adverse pregnancy outcome, and a number of zoonotic pathogens may constitute a risk to pregnant women and their fetuses. With animal contact as a proxy for the risk of zoonotic infection, this study aimed to evaluate pregnancy outcome in women with self-reported occupational or domestic contact with livestock compared to pregnant women without such contact. The Danish National Birth Cohort collected information on pregnancy outcome from 100 418 pregnant women (1996–2002) from which three study populations with occupational and/or domestic exposure to livestock and a reference group of women with no animal contact was sampled. Outcome measures were miscarriage, very preterm birth (before gestational week 32), preterm birth (before 37 gestational weeks), small for gestational age (SGA), and perinatal death. Adverse reproductive outcomes were assessed in four different exposure groups of women with occupational or domestic exposure to livestock with no association found between exposure to livestock and miscarriage, preterm birth, SGA or perinatal death. These findings should diminish general occupational health concerns for pregnant women with exposures to a range of different farm animals.

Laboratory investigations were designed to study the influence of temperature, pH and oxygen tension on the growth of Arthrobotrys oligospora, a nematode-trapping microfungus. Experiments were performed to evaluate the potential role of A. oligospora in destroying third-stage larvae of Cooperia spp. on agar plates and in cattle faeces. The fungus had a growth rate optimum at 23°ree;C and pII 6. Anaerobic cultivation for 23 hours at 23°ree;C and 39°ree;C inhibited fungal growth, but it did not destroy the fungus, which regained growth upon a subsequent shift to aerobic conditions at 23°ree;C. Under experimental conditions in petri-dishes containing agar, the nematode-trapping efficiency of the fungus was striking in that 100% of a population of third-stage larvae of Cooperia spp. was captured within three days of the experiment. The trapping efficiency in faeces was shown to depend upon the inoculation level. At a concentration of approximately 2500 conidia per g faeces, 99% of the larvae were destroyed. The possibilities of using nematode-trapping fungi in controlling animal-parasitic nematodes arc discussed.

Artificially prepared cow pats containing Ostertagia ostertagi eggs were deposited on two pasture plots in May, June and July 1986. Half of the cow pats, placed on one plot, were inoculated with 2000 conidia per gram faeces of the predacious fungus Arthrobotrys oligospora. On the other plot fungus-free control cow pats were placed at the same time. In the faeces generally fewer infective O. ostertagi larvae developed in the inoculated than in the control cow pats. On the herbage around the control cow pats deposited in May, June and July a maxium concentration of infective larvae was found at the same time on the 6th of August 1986. At that time the herbage larval infectivity around inoculated cow pats deposited in May, June and July was subject to a reduction of 48%, 89% and 46%, respectively, compared with fungus-free control cow pats. This experiment indicates that a concentration of 2000 A. oligospora conidia per gram faeces results in a significant lowering of the herbage larval infectivity during the grazing season in Denmark.

Laboratory experiments were designed to select nematophagous fungi that were able to survive in vitro conditions simulating passage through the gastro-intestinal tract of cattle. All of the tests were conducted at 39°C. In a primary stress selection step in diluted rumen fluid, 21 isolates were obtained. Each of the primary stress selected isolates was tested in synthetic saliva, rumen fluid simulating the activity in the rumen, rumen fluid followed by pepsin-hydrochloric acid treatment simulating the additional effect of ruminal and abomasal activity, pepsin-hydrochloric acid solution simulating conditions in the abomasum and finally in a trypsin solution as an example of enzyme activity in the gut. The effect of the rumen fluid alone, or rumen fluid followed by pepsin-hydrochloric acid treatment, were responsible for the reduction in surviving fungal isolates. Only six of thirteen isolates belonging to the genus Arthrobotrys survived while seven of eight isolates of the genus Duddingtonia survived. Fourteen isolates were tested for their predatory capacity in a dung pat bioassay. Fungi of the genera Arthrobotrys and Duddingtonia reduced the development of Ostertagia ostertagi third stage larvae by approximately 75% and 96% respectively compared to the number of larvae that developed from fungus-free control pats.

Three nematode-trapping fungi, one Arthrobotrys oligospora and two Duddingtonia flagrans isolates, were fed to Ostertagia ostertagi-infected calves to test their ability to destroy larvae of this parasite in faeces and consequently to reduce the transmission of infective larvae to herbage. The fungi had previously been selected for their capability to pass the alimentary tract of cattle without losing growth and nematode-trapping potentials. Dung was collected from three calves each fed one of the three fungi and placed as 1-kg cow pats on a parasite-free grass plot together with control cow pats from a calf that was not given fungi. The cow pats contained comparable concentrations of parasite eggs. The two D. flagrans isolates were highly effective in that they reduced herbage larval infectivity by 74–85%. In contrast, A. oligospora did not show any effect in the present experiment. Field experiments will demonstrate if D. flagrans represents a potential organism for biological control of bovine gastrointestinal nematodes under practical agricultural management conditions.

The experiment was designed to test the survival and performance of stress selected nematophagous fungi after passage through the gastro-intestinal tract of cattle. Ruminating calves were fed daily with a fixed amount of fungal material grown on barley grains. The excreted dung was collected on days four and five after the start of the feeding experiment. Barley grains were washed out of the excreted dung and incoculated on water-agar plates. After incubation for one week, nine out of ten fungal isolates were re-isolated from these plates. The predatory capacity of the fungi in the excreted faeces was tested in a dung pat bioassay and a faecal culture system. In the dung pat bioassay. two fungi of the genus Arthrobotrys and six of the genus Duddingtonia reduced the development of Ostertagia ostertagi third stage larvae by 85% (61%–93%). compared to the number of larvae developed from fungus-free control pats. In seven out of these eight isolates, the reduction of larvae in the faecal cultures was 92% (76%–99%).

Artificially prepared cow pats containing Ostertagia ostertagi eggs were deposited on two comparable grazing plots at weekly intervals during June and July 1987. Before deposition the cow pats, on the one plot, were inoculated with 0·250 g mycelial fragments per kg of faeces of the predacious fungus Arthrobotrys oligospora. On the other control plot comparable numbers of non-inoculated cow pats were placed at the same time. Subsequently, in July, two equal groups of calves were turned out one on each plot to graze for two months after which they were necropsied. The number of infective O. ostertagi larvae in inoculated cow pats was reduced by 42% and herbage larval infectivity around them by 50–71% as compared with the corresponding parameters in control pats and surrounding herbage. After a grazing period of two months the calves on the plot with inoculated cow pats had acquired worm burdens that were on average 37% lower than those of calves on the control plot. The lower degree of parasitism in these calves was also reflected in lower egg counts, lower serum pepsinogen levels and higher body weight.

In field experiments, conducted on parasite-free grass plots in two consecutive summers, artificially prepared cow pats containing Cooperia oncophora eggs were inoculated with the nematode-trapping fungus Arthrobotrys oligospora. Numbers of infective C. oncophora larvae isolated from the pats as well as from the surrounding herbage were subject to an approximately teh-fold reduction as compared with numbers in fungus-free pats and herbage surrounding these. This reduction was undoubtedly a result of entrapment of the parasite larvae within the faecal pats.

A field trial was conducted to evaluate the potential of the nematode-destroying fungus Duddingtonia flagrans to control free-living stages of horse strongyles. In late Spring 2 groups of horses (yearlings) with mixed infections of strongyles were allowed to contaminate 2 equal-sized pastures. One of the groups (F) received a daily dose of D. flagrans mixed in a feed supplement, while the other (C) received a similar amount of supplement without fungus. During a 3-month contamination period strongyle egg counts in faeces and number of infective strongyle larvae harvested from faecal cultures were determined. Grass samples were collected fortnightly. After the contamination period the yearlings were removed and 2 groups of young tracer foals (TF and TC) grazed the fungus and control pastures respectively for 4 weeks, housed for another 15 weeks and then killed to determine their worm burdens. The number of larvae in cultures from group TF was significantly lower than that in TC and herbage infectivity was reduced to a very low level on the pasture grazed by horses fed fungi. The number of Strongylus vulgaris and Strongylus edentatus larvae was also significantly lowered in group TF. Cyathostome larvae recovered from the mucosa of the ventral and dorsal colon and from the caecum were significantly lowered in group TF foals. Also, the number of strongyles found in the gut contents of group TF foals were significantly reduced in the dorsal colon, but numbers of worms in the ventral colon and in the caecum were similar to those of the controls.

Ammonia volatilization and denitrification were measured in a ryegrass field in Denmark after direct injection and application with trail hoses of an untreated cattle slurry and an anaerobically digested slurry in late May-early June 1993 and 1994. Ammonia volatilization was measured using a windtunnel system for a period of 8 days after slurry application. Denitrification was measured for a period of 21 days after slurry application. In an adjacent field experiment, nitrogen-uptake (N-uptake) was determined in the first two cuts of the ryegrass harvested after slurry application. N losses through ammonia volatilization were larger in 1993 than in 1994 due to differences in climatic conditions. Ammonia volatilization was lowered substantially (47–72%), when slurry was injected compared with surface application. In 1993 the loss from surface-applied digested slurry was only 35% of total ammoniacal nitrogen (TAN), while the loss from the raw slurry was 47%. There were no significant differences in ammonia volatilization from the two slurry types in the other experiments. N losses through denitrification were low (< 2% of TAN), but there were clear differences in the losses, depending on slurry type, application method and experimental year. Injection of the slurry gave a larger N-uptake in the first cut of grass compared to the trail-hose application. In 1993 N-uptake from the digested slurry treatment gave significantly larger N-uptake compared to the raw slurry in the first cut.