Animal Aid

A Dead Cert : Experiment 10

A Dead Cert

10. Pregnant animals deliberately under-fed

Equine Fertility Unit, Cambridge

Researchers conducted a study on 20 out-of-training Thoroughbred pregnant mares at the Equine Fertility Unit at Cambridge. The aim of the experiments was to assess the effects of a reduced diet on the development of the unborn foal.

A major setback occurred when all of the mares unexpectedly contracted a disease part-way through the study. The disease – known as ‘strangles’ – is usually associated with poor management, especially poor sanitation, crowded conditions and stress.

Prior to being mated, all of the animals were given access to pasture during the day and housed at night. When housed, they were fed individually- adjusted amounts of feed aimed at maintaining a ‘body condition score’ of ‘moderately thin’ or ‘moderate’. Once mated, the mares were divided into two groups. Nine animals were given a ‘moderate food intake’ – including poor quality grazing – while the other 11 received a ‘high food intake’.

At the end of the first trimester of pregnancy, all of the pregnant mares unexpectedly became infected with ‘strangles’.

The disease is characterised by high fever, significant nasal discharge and severe inflammation of the neck and its lymph nodes, some of which may rupture, releasing large amounts of thick, creamy pus. The animals were said to have gradually recovered from the disease over a period of one to four weeks without treatment. All of the mares gave birth at the end of their pregnancy to underweight foals.

In their conclusion, the authors state that their experiment failed to show any difference between the two groups. The fact that the pregnant mares became ill during the study is described by the authors as ‘an unexpected and fascinating insight into the effects of disease-mediated weight loss’ on pregnancy in the mare.

This study was sponsored by the Horseracing Betting Levy Board (Project No. 689).

Wilsher S, Allen WR. Equine Veterinary Journal 2006; 38(6):549-557. Effects of a Streptococcus equi infection- mediated nutritional insult during mid-gestation in primiparous Thoroughbred fillies. Part 1: placental and fetal development.

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