Benefits of mixed grazing

A French study has confirmed that mixed grazing with cattle helps control strongyle worms in horses.

Grazing horses with cattle is often suggested as a useful pasture management tool to help control strongyle parasites. However, there has been little research to assess the benefit.

With a few exceptions of minor significance, gastro-intestinal parasites of horses and cattle are host specific. Thus, infective stages of horse worms ingested by cattle will not develop to adults (and vice versa).

Not only do horses and cattle play host to different species of gastro-intestinal parasites, they also have different grazing habits. Horses tend to graze close to the ground and avoid areas that have been previously contaminated with faeces – producing “lawns” and “roughs.” Cattle, on the other hand, cannot graze so closely to the ground, but will graze areas avoided by horses. 

The study, by Forteau, Dumont and colleagues looked at the management and worm control on horse breeding farms in two regions of France - some of which employed mixed grazing of horses with cattle. 

Forty-four farms were enrolled in the study. These included saddlehorse production farms in Normandy (generally specialised sport horse enterprises, on productive grassland) and northern Massif Central (leisure horses- reared on less productive grassland). Some were specialised horse units; others were mixed cattle and horse farms.

Using surveys and face to face interviews, the researchers recorded details such as stocking rate; proportion of pasture used for grazing only or for cutting and grazing; and the extent of integration of anthelmintic control and pasture management.

Among the findings were:

• many farms were still relying on fenbendazole despite the well-recognised problems of anthelmintic resistance. 
• mixed grazingof horses with cattle was uncommon. Only 8 out of 23 mixed horse and cattle breeders knew that grazing them on the same pasture could be used as part of their strongyle control strategy.
• in young horses last treated with moxidectin, those grazed with cattle had 50% fewer strongyle eggs excreted in their faeces than those grazed in equine-only pastures.

They conclude that mixed grazing of horses with cattle “opens a promising alternative for controlling horse parasitic infection that remains largely unknown by horse breeders.”

For more details, see:

Horses grazing with cattle have reduced strongyle egg count due to the dilution effect and increased reliance on macrocyclic lactones in mixed farms.

Forteau L, Dumont B, Sallé G, Bigot G, Fleurance G.

Animal. 2019 Nov 4:1-7.

doi:10.1017/S1751731119002738

Influence of music on equine night-time behaviour

 Night-time music had a significant effect on behaviour of stabled horses in a recent study.

Research carried out by Naomi Hartmann and Linda Greening in the Equine Science Department of Hartpury University examined the effect of playing classical music to horses at night.

Seven horses, kept on the same yard, were stabled for 24 hours a day and followed the same daily routine. Their behaviour was recorded from 20.30 to 06.30 the following morning for nine nights

For five nights, classical music (Beethoven’s ninth symphony) was played continuously from 20.30 to 01.30. On two nights at the start, and again at the end of the study, no music was played to provide control observations.

The researchers found that music had a significant effect on behaviour. Horses spent more time eating when music was played. Other behaviours – such as standing alert, walking and excreting  - decreased compared to the control periods when no music was played . They also found significant differences in the occurrence of lateral recumbency, although these were not clearly linked to exposure to music.

The researchers conclude: “The addition of music appears to have a significant effect on the equine nocturnal time budget that might be beneficial from an equine sleep perspective.”
 

For more details, see:

A Preliminary Study Investigating the Influence of Auditory Stimulation on the Occurrence of Nocturnal Equine Sleep-Related Behavior in Stabled Horses.

Hartman N, Greening LM.

J Equine Vet Sci. 2019 Nov; 82:102782.

doi:10.1016/j.jevs.2019.07.003

Equine Grass Sickness vaccine trial results

A four-year trial has been unable to show that vaccination can protect against grass sickness.

Evidence suggests that Equine Grass Sickness (EGS) may be associated with the bacterium Clostridium botulinum (C. botulinum) type C, which is found commonly in soil and can produce various toxins.  

Vaccines can protect against tetanus and botulism, diseases caused by closely related bacteria. Hopefully, a similar vaccine could protect against grass sickness.

As it is not possible to reproduce grass sickness experimentally, the researchers conducted a field trial to determine the efficacy of C. botulinum type C vaccination. The aim was to test the ability of the vaccine to prevent naturally occurring EGS by comparing EGS incidence between groups of vaccinated and placebo-treated horses and ponies.

The study was co-ordinated by the Animal Health Trust, in collaboration with the veterinary schools of the Universities of Edinburgh, Liverpool and Surrey, and with support of the Moredun Foundation Equine Grass Sickness Fund.

The research team recruited over 1000 horses and ponies throughout England and Scotland. To be included in the study, the animals had to live on premises where grass sickness had occurred before. Horses and ponies were randomly assigned to two groups: vaccination or control. The primary treatment course comprised three doses of either the vaccine or placebo administered at 21-day intervals. Twelve months later, a further booster dose of either vaccine or placebo was given.

As the study was carried out on premises with a history of grass sickness, the research team anticipated that there would be enough cases to produce a statistically significant difference between the vaccinated and control groups. Unfortunately, only nine cases of grass sickness occurred in the study population – considerably fewer than would have been expected from recent history.

So, unfortunately, the study was unable to reach any conclusion about whether the vaccine was effective in preventing the disease.

However, some useful findings did emerge from the study. The vaccine was shown to be safe and, unlike the placebo, did produce a significant antibody response. Most horses and ponies in the vaccine group had a significant immune response following the primary vaccination course. (C. botulinum type C antibody levels were on average 2.5 times higher after the primary course of injections than before the first vaccination.)

The research team also report that, consistent with previous studies, both young animal age and low C. botulinum type C antibody levels were significantly associated with an increased risk of EGS.

They add that, for the first time, findings from this trial confirmed that low C. botulinum type C antibody levels were found in horses and ponies affected by EGS before the onset of the disease. The results highlighted the key role a horse or pony’s immune response has in their risk of developing EGS. 

Dr Richard Newton, Director of Epidemiology and Disease Surveillance at the Animal Health Trust, said: “Although the EGS field trial did not demonstrate a significant protective effect of the C. botulinum type C vaccine against EGS, this truly unique research has still achieved a number of things.  We now have a greater understanding of equine grass sickness and the trial provided further evidence of vaccine safety under conditions of field use.”

Dr. Jo Ireland from the University of Liverpool added; “We are so grateful to all the veterinary practices, horse owners and supporters who helped make this research possible. The significant amount of data that has been collated during this nationwide field trial will be a very valuable resource for subsequent research studies to benefit future generations of horses and ponies.”

For more details, see:

https://www.aht.org.uk/wp-content/uploads/2019/11/EGS-vaccine-trial-report.pdf