Short Herbage Research Articles

Ingestion of Soil by Grazing Sport Horses.

Simple SummarySoil ingestion has been well documented for the majority of outside reared animals but not in horses. As soil can be a vector of environmental pollutants, such studies generally aim at controlling exposure to pollutant uptake in food producing animals. In horses, ingestion of soil may cause gastrointestinal disorders such as sand colic or intestinal damage. Therefore, soil ingestion has been studied in Irish sport horses grazing at three levels of herbage offer: 2, 3 or 4% of their body weight. Their soil intake was around 4% of the totally ingested dry matter corresponding to 543 to 648 g of dry soil per animal per day, which is quite similar to cattle in normal grazing conditions. Such amounts would clearly be an issue for food safety in areas with contaminated soil but also an animal welfare issue due to gastrointestinal damage. The height of the pastured grass sward seems to be a reliable criterion to indicate the level of risk of soil intake when horses graze short herbage in close proximity to the ground surface and should be moved to a new paddock.Data on soil ingestion in horses are lacking in contrast to other free-range animals. The importance of soil as a vector for environmental pollutants to food is less relevant in horses but several disorders secondary to soil ingestion, such as sand colic or enteritis have been reported. Therefore, soil ingestion has been studied on Irish sport horses grazing at three offered levels of daily herbage: 2, 3 and 4% of their body weight. Soil ingestion was estimated by the faecal recovery of a soil natural marker. Horses had 4.5, 4.1 and 3.7% of soil in their total intake respectively for the 2, 3 and 4% herbage offers. The 4% offer presented significantly less intake (543 g/d) compared to the more restricted offers (624 and 648 g respectively for 3 and 2%). The post-grazing sward height was significantly lower on the 2% offer (3.1 cm) compared to the higher offers (4.1 and 4.4 cm respectively for 3 and 4%). Thus, restricted herbage allowance made grazing closer to the ground and increased soil ingestion. The sward height appeared to be a reliable indicator to manage animal withdrawal from a pasture to limit soil ingestion and the risk of gastrointestinal pathologies caused by it.

The effect of feeding maize silage 1 h or 9 h before the herbage meal on dry matter intake, milk production, nitrogen partitioning and rumen function of lactating dairy cows

The study was conducted to evaluate the effect of the timing of feeding maize silage before a short herbage meal on dry matter (DM) intake, milk production, nitrogen (N) partitioning and rumen function of lactating dairy cows. Ten lactating, pregnant, Friesian × Jersey rumen-fistulated dairy cows aged 4–5 years were blocked in pairs by milksolids (MS; sum of protein and fat) production (1.73 ± 0.097 kg MS/cow.day; mean ± s.d.), bodyweight (519 ± 24.7 kg), days in milk (163 ± 12.5), and body condition score (3.9 ± 0.21). Cows within pairs were randomly allocated to one of two treatments: (1) five cows were offered one-third of their estimated total DM intake (5 kg/cow.day) as maize silage after the afternoon milking at 1500 hours, ~1 h before herbage was provided (1BH); (2) five cows were offered one-third of their estimated total DM intake as maize silage after morning milking at 0700 hours, ~9 h before herbage was provided (9BH). All cows were offered two-thirds of their total estimated DM intake (11 kg/cow.day) over a period of 4 h from 1600 hours to 2000 hours as freshly cut perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens) in an indoor system. Cows were adapted to diets for 9 days (Days 1–9), followed by 5 days of measurement (Days 10–14). Maize silage DM intake did not differ between treatments averaging 5.1 kg DM/cow.day. Herbage DM intake was greater (P = 0.02) for 9BH (11.2 kg DM/cow.day) than 1BH (10.4 kg DM/cow.day). Milk yield (P = 0.001) and MS production (P = 0.08) were greater for 9BH than 1BH (18.8 vs 15.4 kg/cow.day and 1.63 vs 1.48 kg MS/cow.day, respectively). There was no effect of time of supplementation on N partitioned to milk, faeces, or urine. The purine derivatives to creatinine ratio, as an indication of microbial protein production, was greater (P = 0.04) for 9BH than 1BH. Daily mean rumen pH and the concentration of total rumen volatile fatty acids, acetate, butyrate, and ammonia N were not affected by treatment. However, the peak concentration of ruminal ammonia N was 27% lower (P < 0.05) for 9BH than 1BH. The concentration of non-esterified fatty acid (P = 0.03) and beta-hydroxy butyric acid (P = 0.01) were greater for 1BH than 9BH (0.14 vs 0.09 and 0.81 vs 0.71 mmol/L, respectively). These results indicate that under herbage feed restriction, altering the time of supplementation relative to the herbage meal can increase herbage DM intake and subsequent milk production.

Survival of infective Ostertagia ostertagi larvae on pasture plots under different simulated grazing conditions

This study was carried out to examine the survival of infective Ostertagia ostertagi larvae (L 3) on pasture under different simulated conditions of grazing, i.e. mixed grazing of cattle and nose-ringed sows, or grazing by cattle alone. Standardised pats of cattle faeces containing O. ostertagi eggs were deposited on three types of herbage plots, which were divided into zone 1: faecal pat; zone 2: a circle extending 25 cm from the edge of the faecal pat; zone 3: a circle extending 25 cm from the edge of zone 2. For “tall herbage” (TH) plots, the herbage in zone 2 was allowed to grow naturally, while the herbage in zone 3 was cut down to 5–7 cm fortnightly, imitating a cattle-only pasture. For “short herbage” (SH) plots, the herbage in both zones 2 and 3 were cut down to 5–7 cm fortnightly, imitating mixed grazing of cattle and sows. The grass in the “short herbage and scattered faeces” (SH/SF) plots were cut as for SH plots, and the faeces were broken down 3 weeks after deposition and scattered within zone 2, imitating the rooting behaviour of co-grazing sows. Five faecal pats from each plot group were collected on monthly basis, along with the herbage from zones 2 and 3 cut down to the ground. Infective larvae were then recovered from both faeces and herbage. The numbers of L 3 recovered from zone 1 were higher in the TH plots than in the other two groups and, furthermore, the larval counts from SH plots were always higher than from SH/SF plots. The three groups followed a similar pattern during the season regarding numbers of L 3 in zone 2, and no clear patterns between plot types were obtained. The presence of L 3 in zone 3 was almost negligible. Important differences were seen throughout the study from the biological point of view; more L 3 were able to survive in faeces on the TH plots, presumably reflecting a better protection from heat and desiccation compared to those in the other plots. The overall results support the idea that mixed grazing of cattle and pigs favour the reduction of O. ostertagi larval levels in pasture. This reduction is mainly due to the grazing behaviour of pigs, which by grazing up to the very edge of the cattle faeces, will either expose the larvae in faeces to adverse environmental summer conditions or ingest cattle parasite larvae, or both.

Effects of irrigation on appearance and survival of infective larvae of goat gastro-intestinal nematodes in guadeloupe (French West Indies)

In Guadeloupe (French West Indies), faeces from naturally infected goats were deposited during the dry season on three plots, irrigated with long (plot A) or short herbage (B) and non-irrigated with long herbage (C). Microclimatic data and the evolution of L3 population size in faeces, on soil surface and on herbage were followed over a period of 26 days. The initial nematode egg population was comprised of 58% Haemonchus contortus (HC), 25% Trichostrongylus colubriformis (TC) and 17% Oesophagostomum columbianum (OC). Temperature and water content varied in time and space (soil, faeces, herbage) from homogeneous in A to very heterogeneous in C. In A and B, population dynamics were similar with higher values of maxima in A. Larval peaks occurred on day 9 after deposition in faeces in plot A: 23.1, 39.1 and 17.2 L3/100 eggs, respectively for HC, TC and OC; the same day in soil: 1.9, 0.6 and 3.1 L3/100 eggs. On day 26 it remained less than 1 L3/100 eggs in both soil and herbage for the three species. In C, only TC larvae were observed coming, after rain, from eggs in which hatching had been delayed. It was difficult to separate the respective effects of temperature and water content on the development of the eggs, but irrigation gave favourable conditions for all eggs to develop into larvae. Pasture rotation with 28–35 days of regrowth should minimize the increased risk of infection for the goats due to irrigation.

Observations on the bionomics of the free-living stages of Trichostrongylus vitrinus.

Eggs of Trichostrongylus vitrinus in faecal pellets deposited on grass plots each month from April 1981 to March 1982 developed into infective larvae. From October to March development was slow and mortality of the pre-infective stages was very high. From April to September development was more rapid. The weather was generally dry and mortality of the pre-infective stages was high on plots with short herbage but was lower on most of the plots with long herbage, especially in July and August. In the laboratory, development of eggs into infective larvae was completed at temperatures ranging from 4 degrees C to 27 degrees C in faecal pellets which were either kept moist or dried out slowly, but not in faecal pellets which dried out rapidly. The rate of development increased as the temperature rose. Infective larvae survived for up to 16 months on the herbage of grass plots; some survived during very cold weather in the winter of 1981/82. In the laboratory, infective larvae suspended in tap water survived even longer at 4 degrees C and 10 degrees C but not at higher temperatures. They were rapidly killed by continuous freezing. They survived for up to 8 weeks when subjected to desiccation. The relationship between climatic conditions and the development and survival of the free-living stages is discussed.

The Distribution of Excreta on New Forest Grassland Used by Cattle, Ponies and Deer

(1) The distribution of excreta on areas of reseeded grassland in the New Forest used by free-ranging cattle, ponies and fallow deer was shown to be non-random. Distinct latrine areas were recognized where the faeces of all three herbivore species were concentrated, and where the majority of urinations occurred. The mosaic of latrine and non-latrine areas can be detected in aerial photographs in which non-latrine areas appear as light-grey patches set in a matrix of the dark grey latrine areas. During the 3 years of the study the position of the mosaic proved to be relatively stable. (2) The latrine areas were characterized by an uneven sward about 50 mm tall with abundant thistles (Cirsium spp.) and ragwort (Senecio jacobaea). Non-latrine areas had an even and very closely cropped sward between 10 and 20 mm tall. Soil chemical analysis of the two kinds of area revealed significantly higher levels of exchangeable potassium in latrine areas, and on one site significantly higher levels of magnesium and organic matter. No significant differences were detected in soil reaction, nor in phosphorus or calcium levels. (3) Observations of grazing animals revealed a tendency, at all times of year, for ponies to avoid grazing in latrine areas. In winter and spring this tendency was very slight, but from midsummer until late autumn a substantial majority of grazing ponies were to be found in non-latrine areas. In contrast, only 2% of the cattle observations made over a period of 20 months were of animals grazing in non-latrine areas. (4) The standing crop of dung and the rate of dung production on the two kinds of area were monitored for 12 months on one lawn. The amount of pony dung produced on non-latrine areas was only 16.5% of that in latrine areas, while for cattle the corresponding value was 28-7%. It is argued that the observed pattern has been created by selective grazing and eliminatory behaviour of the ponies, and that the excreta of cattle and deer are largely confined to pony latrine areas because these animals are unable to graze the very short herbage of non-latrine areas.

Observations on the development and survival of the free-living stages of Hyostrongylus rubidus both in their natural environments out-of-doors and under controlled conditions in the laboratory.

Faces containing eggs of Hyostrongylus rubidus were deposited on grass plots each month throughout 1980. Eggs in faeces deposited on plots from May to October developed into infective larvae but in May development was completed only in artificially moistened faeces, the weather was warm and dry and natural faeces dried out rapidly resulting in the death of eggs and pre-infective larvae. For the remainder of this period the weather was sufficiently warm and wet for development to be completed. More eggs developed into infective larvae on plots with well-grown herbage than on plots with short herbage. In April a few eggs survived and developed into 1st-stage larvae but no further development took place. In the laboratory development was completed at temperatures ranging from 10 to 27 degrees C but no development took place at 4 degrees C. Out-of-doors infective larvae survived on herbage for up to 10 months while in the laboratory, infective larvae suspended in tap water survived even longer to 10 and 22 degrees C, but the larvae were rapidly killed by continuous freezing and by desiccation when the relative humidity was less than 95%. The relationship between climatic conditions and the development and survival of the free-living stages is discussed and a comparison made with the free-living stages of Oesophagostomum dentatum.

The relationship between pasture herbage and the development and survival of the free-living stages of Oesophagostomum dentatum

ABSTRACTPlots of pastureland with well grown herbage provided a more favourable environment for the survival and development of the free-living stages of Oesophagostomum dentatum in faeces during warm dry weather than did plots with short herbage. This was because well grown herbage gave better protection against the unfavourable effects of dryness than did short herbage. There was no significant difference between the plots during cool wet weather.

SWARD GROWTH IN RELATION TO PATTERN OF DEFOLIATION

It is suggested that the growth of a grass sward may be affected by heterogeneity of plant height. An initial test of this possibility was made by cutting a stand of Dactylis glomerata in such a way as to produce adjacent areas of tall and short herbage. This pattern was obtained by using three different cutting treatments, two of which gave yields which were greater than predicted from controls. The results are discussed in relation to alternative methods of harvesting grass.

Facial eczema on long and short herbage

Abstract In trials during the 1959–60 and 1960–1 seasons, counts of the spores of the fungus Pithomyces chartarum (Berk. & Curl.) M. B. Ellis were higher on short than on long pasture, and more liver damage occurred in lambs grazing the shorter herbage. No conclusions were reached on whether pre-treatments of the test areas, either by grazing or silage-making, affected the results. The results illustrate some of the difficulties in evaluating the effects of typical management practices, such as grazing or silage-making, as distinct from an atypical practice such as repeated gang-mowing, on the incidence and severity of facial eczema, particularly when weather and pasture conditions are unfavourable for outbreaks of the disease.

Effects of season of growth and digestibility of herbage on intake by grazing dairy cows

SUMMARY1. The intakes of herbage organic matter (OM) and digestible organic matter (DOM) by twenty dairy cows were measured during two periods of strip grazing on one pasture, in spring and late summer of the same year.2. Results from the first 5-day measurement period in the spring suggested that intakes at this time were restricted primarily because the cows had difficulty in gathering the short herbage. Measurements on ten of the cows continued during a further 5 weeks while the digestibility of the OM of grazed herbage declined from about 80 to 68%. There was a fall of about 20% in DOM intake by the cows during this period; one-quarter of the fall could be ascribed to a reduction in OM intake and the remainder to the decline in digestibility as such.3. Intakes were measured during two weeks in late summer and were compared with those measured during two weeks in the spring when the digestibility of the grazed herbage was similar. Intakes of DOM expressed as lb./lb. live-weight0·73 were the lower by about 10% in the late summer, or by from 10 to 20% in terms of DOM available for production when allowance had been made for maintenance requirements. This finding is discussed in relation to practical experience of the feeding value of autumn grass.

Some observations on the free living stages of the cattle lungworm in relation to their natural environment

Summary Observations on pats of faeces out of doors and on the surrounding herbage indicated that the period of survival varied from season to season, though the initial mortality was heavy throughout the year. In May the larvae survived for only 4 weeks but they persisted for 13 weeks from October to January. The majority of the surviving larvae remained in the faeces and did not migrate on to the herbage. Experiments with infected faeces placed on rapidly growing grasses in boxes showed that survival in autumn was longer than in early summer. The largest number of infective larvae is recoverable from the herbage when the faeces have been thinly spread upon it. When the herbage is long the initial survival in these thin films of faeces is favoured, especially in autumn. The longevity of larvae within an undisturbed pat of faeces is influenced to only a limited degree by the character of the surrounding herbage. On the other hand the longevity of the small numbers of larvae which have migrated out of the faeces is markedly greater in long than in short herbage. It is concluded that for larvae to get onto the herbage in meaningful numbers it is necessary for the faeces themselves to get on to the herbage. The relevance of these findings to the process of infection and the epidemiology of husk is discussed.

Geographical Notes

Geographical Notes