16 February 2018

5 minute read

A farm health plan should consider the role of parasites throughout the life of a dairy cow and how and when they will be managed. Regular measurement of weight gain and loss, fertility parameters and behaviour observations can identify productivity-limiting parasite burdens at an early stage, and prevent avoidable losses. Key phases in a cow’s productive life include early life, heifer growth, transition to the milking herd, and lactation.

Nicky Bowden, ruminant veterinary advisor at Boehringer Ingelheim, says: “Losses in potential liveweight gain due to poor parasite control during a heifer’s first grazing season will not be recouped during the second year at grass [1]. Affected animals will not catch up, and this will impact on their ability to meet important growth milestones, which could result in an increased age at first calving.

“Efficient and cost-effective heifer rearing can make a big difference to lifetime profitability. It can support herd expansion without the need to buy in replacements and also increase the rate of genetic improvement.”

The cost benefits of producing heifers that calve at 24 months are significant, and include reduced culling and increased lifetime profitability. Lifetime production can increase by an extra quarter to half a lactation, which could amount to £529* in extra milk yield alone.

Effective worming of first and second season grazing animals can reduce the impact of parasites on growth and fertility levels in growing cattle, while still allowing them to build the necessary immunity required to prevent clinical disease in adulthood.

Cows that carry parasites eat less forage and those at grass will graze for less time than wormed cows, reducing the opportunity for sustained growth. In trials, heifers that had been treated to remove gutworm gained 0.8kg/day compared to untreated heifers, which gained only 0.65 kg/day [2]. Increased mammary development and earlier onset of puberty in strategically wormed heifers compared to those left untreated has also been shown [3,4].

“The dry period and transition are the next stages that require particular attention,” says Nicky.

“The dry period is critical for setting a cow up for her next lactation and pregnancy so it pays to get it right. Trimming feet, implementing appropriate dry cow therapy and controlling parasites are vital elements in a transitional cow health plan.

“Treating cows in transition with an appropriate anthelmintic will reduce the impact of parasites on the energy gap post-calving, which can reduce milk yield and increase the period between calving and conception [5,6].. Using a zero milk-withhold anthelmintic will remove a wide range of worm species without potential lost milk sales.”

Farmers should not be complacent about parasite control once heifers have joined the milking herd.

At grass, cows that have been wormed to remove gutworm will graze for an additional 47 to 50 minutes, 7.5% more than untreated cattle6. Managing feed intake is a key part of sustaining an optimal milk yield curve. Worming can also improve fertility parameters such as improving the calving to conception rate and reducing the number of services required6.

Once in lactation, cows at grass may benefit from further treatments of products like EPRINEX Pour On during the grazing season where pasture contamination from gutworm and lungworm larvae is high. Managing exposure to lungworm through targeted treatments in line with a herd health plan can prevent clinical disease and reduce the impact of these parasites on milk yield and cow health. While managing gutworm burdens can protect milk yield and make the most of grass.

“The whole life approach to parasite control really does make a difference to overall lifetime productivity of dairy cows, and ultimately increases profitability per head. At a time when dairy farm returns continue to be challenging, every penny of extra profit makes a difference,” concludes Nicky.

References

* calculated as: annual average milk yield in 2017 (7557 l/cow) divided by 300 day average lactation period to give average daily milk yield of 2519 litres per cow per day, multiplied by the average milk price for standard liquid milk contracts in 2017 of 28.04 ppl for a quarter of a lactation (75 days).

1.Larsson et al. (2011) Performance of second-season grazing cattle following different levels of parasite control in their first grazing season. Veterinary Parasitology 175 (2011) 134-140
2. Forbes et al. (2000) Evaluation of the effects of nematode parasitism on grazing behaviour,
3. Mejía et al (2009) Effect of anthelmintics on reproductive performance and first lactation culling rate in Holstein heifers. Vet Rec 165: 143–146
4. Perria et al (2013) Gastrointestinal parasite control during prepuberty improves mammary parenchyma development in Holstein heifers. Vet Parasitol 198:345-350
5. Forbes et al. (2004) Impact of eprinomectin on grazing behaviour and performance in dairy cattle with sub-clinical gastrointestinal nematode infections under continuous stocking management. Vet Parasitol 125, 353-364
6. McPherson et al. Proceedings of the American Association of Veterinary Parasitologists. 44th Annual Meeting, New Orleans, Louisiana, USA, 1999 Abstr. 28.

*EPRINEX^® 0.5% w/v Pour-On for Beef and Dairy Cattle contains eprinomectin. IVOMEC® Classic Pour-on for Cattle contains ivermectin. UK: POM-VPS. Further information available in the SPC or from Merial Animal Health Ltd, CM19 5TG, UK. UK Tel: 0870 6000 123. EPRINEX® and IVOMEC® are registered trademarks of Merial. ©2018 Merial Animal Health Ltd. All rights reserved. Merial is now part of Boehringer Ingelheim. Date of preparation: February 2018 AHD10599 Use Medicines Responsibly.

About Merial

On January 1st, 2017, Merial became part of the Boehringer Ingelheim group. As the second largest animal health business in the world, Boehringer Ingelheim is committed to making the industry even better at improving animal health. With more than 10,000 employees worldwide, Boehringer Ingelheim Animal Health has products available in more than 150 markets and a global presence in 99 countries. For more information about Boehringer Ingelheim Animal Health, visit:www.boehringer-ingelheim.com/animal-health/overview.