“Systematic use of antiparasitics on
dairy farms and commercial
advantages”
Dr. Barry McInerney
MVB MRCVS MSc
Head of Clinical Development
Norbrook Laboratories GB Ltd
Dairy farming in the UK
• 95 per cent of the dairy herd in the UK are the black and
white Holstein breed
– Produce 6,000-12,000 litres of milk in a single lactation
– Beef breeds produce approximately 1,000 litres in a single lactation
• Enough to feed suckling calf
• Large breed holsteins
– In calf 15 months of age – aim for 350-400 kg bodyweight
– Calve at 24 months of age
• aim for post-calving body weight of 565kg
– 80-85% of their mature body weight
– A dairy cow will continue to grow and reach mature body weight
during the 4th or the 5th lactation (e.g. > 700 kg for Holsteins)
There is a strong relationship between body weight at first
calving and first lactation milk yield and lifetime production
Parasitic gastroenteritis (PGE)
• Cattle can be parasitised by over 18 species of
gastrointestinal nematodes
• The most economically important species is
Ostertagia ostertagi (followed by Haemonchus spp.
and Cooperia spp.)
• Ostertagia ostertagi
– Ingested ostertagia larvae burrow into the lining of the
abomasum, moult to L4 and emerge as adult worms.
– Pre-patent period of 3-4 weeks, i.e. from ingestion to the
appearance of eggs in the faeces.
Parasitic gastroenteritis (PGE)
• Ostertagia ostertagi
– In a normal abomasum, the pH of the contents maintained at 2
to 2.5
• when large numbers of the parietal cells are lost, the pH of the
abomasal contents may rise to pH 7 resulting in a protein losing
gastropathy
a)
b)
c)
d)
pepsinogen is not activated to its active form, pepsin, (principal
proteolytic enzyme in the stomach and degrade proteins to peptides)
proteins are not denatured and digested
there is an increase in the number of bacteria in the abomasum
there is leakage of blood and blood-proteins into gut
– Together with anorexia, this gastropathy and impaired protein
digestion leads to hypoproteinaemia, weight loss, persistent
diarrhoea and emaciation
– Severe infections may cause death
Parasitic gastroenteritis (PGE)
• Host immunity to PGE
– acquired immunity is slow to develop
– calves do not achieve any significant level of immunity
until the end of their first grazing season
– by the second and third year of grazing, adult stock usually
have a strong immunity
Parasitic gastroenteritis (PGE)
• Host immunity to PGE
– However, immunity is not “sterile” - does not remove
infection totally
• adult cattle can frequently harbour high O. ostertagi burdens,
which in some individuals may result in clinical disease
– Affected by
» Intensification
» Overuse of anthelmintics
PGE in dairy cows
• Host immunity to PGE (contd.)
– Additionally, around the periparturient period when
immunity wanes there are reports of clinical disease
following calving, particularly in heifers
– housing over the winter allows the immunity to wane
• at turnout are susceptible to re-infection, subsequently
contaminating the pasture
• immunity is re-established following re-exposure and any clinical
signs which occur are usually of a transient nature
Infections with GI nematodes are an underestimated
cause of reduced performance in pastured dairy herds
PGE in Dairy Cows
• Intensification of livestock farming, improved farming
efficiency, etc. increase the risk of disease
Together with liver fluke, gastrointestinal worms have
been ranked as the top two causes of livestock
productivity losses in the EU
• Nowadays, the major impact of parasitism is due to subclinical infections causing production losses that affect
the production of meat, milk and the value of fibre,
fleece/hide and skin products.
PGE in Dairy Cows
• Previously assumed adult dairy cows could easily deal
with parasitic infection and minimise any production
effects
• Recent evidence of negative impact of GI nematodes on
the productive performance of adult dairy cows
• Adult dairy cows
– Recent abattoir surveys carried out throughout the EU - 83 to
100 per cent of culled dairy cows were infected with
gastrointestinal nematodes
PGE in Dairy Cows
• More often than not is subclinical in nature
– no outward signs of GI nematode infection
– compared to uninfected controls under
experimental conditions
• Reduction in milk yield of 1.2-2.2kg milk/cow/day
Lungworm in dairy cows
• Worms build up on grass in early part of the year
leading to increased risk in late summer, early autumn
• Outbreaks commonly seen July to September
• Dairy stock predisposed.
• Compared to GI worms, low numbers of lungworm
larvae are all that is required to cause clinical disease
Lungworm in dairy cows
• An increase in the number of older cattle
affected has been reported
– attributed to the efficiency of some prophylactic
anthelmintic regimens
– prevents exposure and development of acquired
immunity
• Some adults will contract subclinical infections
during which they act as a source of further
larval contamination
Lungworm in dairy cows
• Occasionally clinical disease may recur when:
– previously infected adults or groups that have not
been exposed to reinfection for >1 yr
– and in which immunity may have waned
– are exposed to an overwhelming level of infection
Lungworm
• In growing cattle:
– losses from sudden death in severely affected cattle
– less severely affected cattle suffer a marked loss of body
condition
• up to 10 per cent bodyweight
• 20 to 40 kgs in growing cattle
– convalescence is protracted with extended periods to slaughter
weights
• up to three months
– secondary bacterial pneumonia can follow lung damage
necessitating antibiotic therapy
Losses in a severe outbreak of lungworm in growing cattle
can average up to £50 per head.
Lungworm
• In dairy cattle:
With very large larval numbers on pasture, disease can
occur in adult cattle vaccinated as calves but not
subsequently challenged for several years
– a dramatic reduction in milk yields of up to 50 per cent
– possible deaths
– lost milk production could reach £1.50 to £3 per head per
day with recovery taking 10 to 20 days after treatment.
Lice in cattle
• Lice cause irritation of the skin
– leads to biting, scratching and rubbing by affected cattle
– affected cattle will have
•
•
•
•
unthrifty appearance
rough coat
lowered production
damaged hide
• Feed intake of cattle affected by external parasites can drop by 8-10%
– in severe infestations, there may be loss of hair and local scarification, and
anaemia can be seen with extreme infestation with sucking lice
• In the UK “light spot and fleck” caused by biting lice and sucking lice cause
is estimated to cost the leather industry £20 million per year (NADIS 20032007).
Dairy cows
• Production benefits of eprinomectin
treatment in dairy cows
– Increased milk yield
• Daily milk yield increase of 2.14 litres per day – 21.08 V
23.22 litres per day
• Average increase of 0.35kg-0.63kg/cow/day for
duration of lactation
• Predicted estimate of 307kg more than untreated
controls over a 305 day lactation
PGE in Dairy Cows
• Benefits of eprinomectin treatment in dairy cows
(contd.)
– Improved quality of the milk
• consistently higher milk fat, protein and overall milk solids
– Increased dry matter intake (DMI) by up to 1kg per day
• DMI and milk yield positively correlated
• Every kg of DMI = 2.0 – 2.5 kg milk
– Improved yield - up to 2.35kg/day - particularly marked in heifers
– Improved fertility
• improved calving to conception intervals
• higher conception rates at first service
– 58% treated animals V 38% non-treated
Eprizero® 5mg/ml
Eprizero® Pour-On
• A clear to very light yellow pour-on solution containing
5mg/ml of eprinomectin:
– Member of the macrocyclic lactone class of anthelmintics
– Bind selectively and with high affinity to glutamate-gated
chloride ion channels which occur in invertebrate nerve or
muscle cells
• leads to an increase in the permeability of the cell membrane to
chloride ions
• hyperpolarization of the nerve or muscle cell
• blocks the transmission of neuronal signals of the parasites
• paralysis and death of the parasite
– May also interact with other chloride channels
• gamma-aminobutyric acid (GABA) gated chloride ion channels
Eprizero® Pour-On
• Indicated for the treatment and prevention of the
following parasites:
– Gastrointestinal Roundworms (adults and fourth stage
larvae):
– Lungworms (adults and fourth stage larvae):
– Warbles (parasitic stages):
– Mange Mites:
– Lice:
– Horn Flies:
Eprizero® Pour-On
• Dose rate - 1 ml/10 kg of bodyweight
– 0.5 mg eprinomectin per kg bodyweight
• Apply topically along backline in a narrow strip
extending from the withers to the tailhead
• Persistency of 28 days against the most economically
damaging worms affecting cattle
– Ostertagia ostertagi
– Dictyocaulus viviparus
Eprizero® Pour-On
• Zero milk withdrawal period
• 10 day meat & offal withdrawal period
• Rainfast
– Rainfall at anytime before or after treatment will not affect the
efficacy of the product
• Wide safety margin
– mammals do not have glutamate-gated chloride channels
– macrocyclic lactones have a low affinity for other mammalian ligandgated chloride channels
– do not readily cross the blood-brain barrier
Eprizero® Pour-On
• Safe for use during all stages of pregnancy and lactation
• Safe for use in cows producing milk for human
consumption
• Safe for use in breeding bulls
• Contraindications/warnings
– Keep treated cattle away from water bodies for two to four
weeks after treatment
Eprizero® 5mg/ml Pour-On
- summary
Eprizero® 5mg/ml Pour-On can be used
strategically at any stage of lactation, with the
assurance of giving your dairy cows and
valuable replacements the best possible
protection against gut and lungworms,
optimizing lifetime production and maximising
profits