Over the last number of weeks, we have seen the emergence of flies and all the trouble that brings to farms. In this article we will look at a belt and braces approach to fly control.

Cattle farmers in Ireland must prepare for the increased presence of flies, which can pose significant health risks to their livestock. Flies not only cause annoyance and stress to cattle, but they can also contribute to the spread of diseases, including summer mastitis. In this article, we will discuss the diseases flies can transmit to cattle in grass, the impact of fly stress, and various fly control mechanisms, including pharmacological solutions and alternative methods. Specifically, we will focus on fly control and its relationship to mastitis in dry heifers and cows.

Flies are notorious carriers of various diseases that can affect cattle. In Ireland, common diseases transmitted by flies include:

  1. Pink Eye (Infectious Bovine Keratoconjunctivitis): Flies mechanically spread the bacteria responsible for pink eye, leading to painful inflammation of the eyes and potential vision impairment in affected cattle.
  2. Summer Mastitis: This condition occurs when flies introduce bacteria into the teat canal, resulting in mastitis. Dry heifers and cows are particularly susceptible, making effective fly control vital in preventing this costly disease. This is a hugely costly disease particularly in heifers and dry cows as the infected quarter will usually never return to milk. In severe cases, it can be life-threatening in animals.

Don’t underestimate the stress of flies on cows

Flies cause significant stress to cattle, affecting their overall health and productivity. The constant annoyance and discomfort from fly worrying can lead to behavioral changes, reduced feed intake, weight loss, and impaired reproductive performance. Additionally, stressed cattle may be more susceptible to diseases and exhibit decreased immune function. Therefore, implementing effective fly control measures is crucial to minimize both physical and psychological stress on the herd.

Technical Fly Control Mechanisms:

  1. Several pharmacological options are available for fly control in cattle. Pour-on and spray insecticides containing active ingredients such as pyrethroids, organophosphates, or macrocyclic lactones can be used. These products are applied directly to the animal’s body or environment and help repel or kill flies. Speak with your vet about what is available and licensed for fly control in your herd.

Top tip: When applying a fly spot on/pour on, apply some also to the end of the tail or tail swish. This helps in my experience reduce the fly burden around the udder.

  1. Ear tags impregnated with insecticides provide a sustained release of the active ingredient, effectively repelling or killing flies for an extended period. They are particularly useful in controlling horn flies, which primarily reside on the head, neck, and shoulders of cattle.
  2. Many farmers will also apply biological or homemade remedies.  One common recipe combines equal parts water and apple cider vinegar with a few drops of essential oils like citronella, eucalyptus, or lavender. This mixture can be sprayed directly onto the heifers or applied to a cloth and wiped onto their bodies. However, it’s important to note that homemade fly repellents may not be as long-lasting or potent as commercially available products.
  3. Some farms may utilise boluses/licks often containing garlic also to deter flies landing on cattle.

Alternative Fly Control Methods:

  1. Fly Traps and Sticky Tapes: Various types of fly traps, such as sticky tapes and baited traps, can help reduce fly populations around the farm. These traps attract and capture flies, helping to break the breeding cycle and control their numbers. In my experience, they can help but need to be put out early during fly emergence.
  2. Biological Control: Introducing fly predators, such as parasitic wasps, can help control fly populations naturally. These beneficial insects target fly larvae, preventing them from developing into adult flies. Implementing biological control methods can be a sustainable and environmentally friendly approach to fly control.

Fly Control and Mastitis in Heifers and Dry Cows:

Effective fly control is crucial in preventing mastitis in dry heifers and cows. Flies can introduce mastitis-causing bacteria into the teat canal, leading to inflammation and infection. Implementing fly control measures tailored to the specific needs of dry cows/ heifers, such as regular application of insecticides, fly repellent sprays, and insecticidal ear tags can significantly reduce the risk of mastitis transmission.

As part of fly control, I have been using external teat tips during high-risk periods particularly where heifers are prone to high fly burdens.

External teat seals provide a physical barrier that helps prevent flies from gaining access to the teat canal during risk periods.

Proper fly control during the summer months is essential for maintaining the health and productivity of cattle.

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