A group of animals, usually cattle, or pigs, or related wild animal species, which live a collective life together. This may be a natural pattern of behavior or be imposed by a human operated management system.
- h. abnormality — an abnormality detectable only by examination of epidemiological data, e.g. milk yield per hectare, conception rate to first service.
- h. composition — includes bulls (where applicable), cows in milk, dry cows, heifers not yet calved, bred heifers, virgin heifers, yearlings, calves weaned and suckers or at foot. Called also herd structure.
- h. diagnosis — a diagnosis made to fit a herd problem which may be, for example, a low reproduction rate, or wool yield, or win rate at the races.
- dairy h. — herd used exclusively for milk production.
- h. epidemic — an epidemic confined to one herd.
- h. fertility control scheme — programs based on surveillance of all reproduction data and comparison of indexes with preset targets. Correction of inefficiencies may be implemented by the farmer but diagnosis of the cause and treatments and prophylaxes are largely the province of the veterinarian.
- h. health program — a health management system based on periodic visits to the herd by a veterinarian to check the status of a series of identifiable health parameters including production, reproductive efficiency, mastitis prevalence, calf survival, cow culling and mortality rate, fecal egg counts. Superior programs also include production management so that genetics, nutrition, housing, disease control and financial management are coordinated in a wholefarm approach.
- h. immunity — a level of resistance in a herd or flock which is sufficient to prevent the entry of a particular disease into, or its spread within, the herd. The resistance may be innate, a genetically based resistance, or acquired as a result of previous exposure to the particular agent or of vaccination. The general usage of the term relates to the prevention of spread of infection at an epidemic level. So that in a herd in which there are 70 to 80% of immune animals there may be sporadic cases but the prevalence is unlikely to be significant. The same comments apply to larger populations, e.g. a wild animal or companion animal population which is really not managed as a herd.
- h. level test — test performed on the entire herd or an adequate sample of it.
- rolling h. average (RHA) — the average milk production per herd per year based on the 12 months just finished. Upon completion of a new test record, usually at monthly intervals, the record for the same period of the previous year is deducted and the new record is added, then a new rolling 365-day average is calculated. RHSs are updated with each new test. See also
moving average. - h. sampling — examination, either physical or clinical pathological, of a herd to determine the herd status in a particular epidemiological parameter.
- h. size — a critical factor in planning for productivity efficiency. May be quoted as the number of animals of a particular age or stage of production, e.g. milking cows, assuming that other, usually young, stock are also carried on the farm.
- h. structure — see herd composition (above).
- h. udder health — status of the herd with respect to the prevalence of quarter infection, clinical mastitis, teat lesions.
