A guide to supplementing colostrum at calving

larger follicles may contain postmature eggs that are not competent for fertilisation. Some studies show that heat stress depresses LH secretion and compromises its function, which releases the egg at the wrong time (Wolfenson & Roth, 2019). In addition, heat stress increases the secretion of FHS causing the larger number of follicles growing. Heat stress also a ects the development and rate of growth of the early embryo, resulting in early embryonic loss (Dei, 2020).

How do you know if heat stress is a ecting fertility? Farmers often look at milk yield as an indicator of heat stress. However, data collected by Mark Scott (Cargill) suggests that milk protein yield drops at a Temperature Humidity Index (THI) of 68; however, at a THI of 57 oestrus activity reduces inseminations in the herd and at a THI 65 conception rates drops. So, before milk yield even begins to drop fertility has already been detrimentally a ected and if the THI is sustained for longer than a 24-hour period or occurs on consecutive days then it is likely to a ect fertility for a further three weeks (Mark Scott, Cargill).

IgG, which equates to 22 Brix when measured with a refractometer. In new guidelines, it is now recommended calves receive a minimum of three litres within the rst two hours of life and additional 3–4 litres within 6–12 hours of birth – for a total of 6–7 litres of high-quality colostrum within its rst 12 hours of life.

“To be delivered to the blood supply, IgG molecules are absorbed by the small intestine, and rapidly decline after 12 hours of life. This makes timing critical to maternal colostrum absorption,” adds Ms Hall.

To meet the recommended benchmarks for passive transfer, she recommends producers stop relying on calves to suckle unsupervised and to test colostrum quality with a refractometer.

If you are an all-year-round calving herd then the sustained heat during July and August could continue to cause you problems the following spring, with a disruption to the calving pattern resulting in a gap in calves being born.

To reduce heat stress, building design should be assessed to ensure there is su cient inlet of air and an outlet for the exhaust of warm, stale air (e.g. open ridge). Natural ventilation can be increased by removing boarding and exchanging for a product which allows variable ventilation, and also provides weather protection when needed. Mechanical ventilation such as traditional fans or innovative cooling tubes can further enhance cooling within the shed. FG being delivered into the rumen.”

When colostrum quality is below the recommended 22 Brix or below the minimum six litres, supplementation is required. To capture the bene t of passive immunity from on-farm pathogens, Ms Hall recommends maternal dam colostrum from a cow on the same farm. When it is not available or is going to take too long to thaw out for the rst feed, supplement with a full fat colostrum powder sourced from UK herds like Nettex’s Calf Colostrum Double Strength. This can support calf performance when calves are not receiving su cient good quality maternal colostrum. It also contains growth factors, hormones, vitamins and minerals.

Industry research has found 61% of dairy calves and 20% of suckler calves left to suckle the dam for colostrum did not receive enough IgG antibodies for successful passive transfer.

Emily Hall, livestock farmer and product manager for Nettex, says: “Passive transfer of diseaseghting antibodies from the dam is reliant on feeding enough high-quality maternal colostrum as quickly as possible after birth. Simple management measures can be taken to ensure more passive transfer success rates to give calves a stronger start to life.”

For successful passive transfer of IgG antibodies, colostrum quality needs to be a minimum of 50g/l

“Studies have found 20–25% of calves don’t feed from the dam within the rst eight hours of life and few consume enough colostrum within the peak absorption window. Feeding colostrum via a bottle is preferable since the sucking re ex allows milk to go straight into the abomasum for fast absorption by the small intestine. While tubing is preferable to leaving the calf to suckle the dam, it will delay absorption by 2–4 hours due to

Collected from Scottish farms speci cally for UK herds, Nettex’s colostrum range is free from TB, Johne’s and EBL. It is also of known quality and has been tested for safety and e cacy – giving producers a quick and convenient colostrum supplement. Ms

Hall concludes: “Calf Colostrum Double Strength is a great option to deliver high quality bovine colostrum to calves in a short amount of time.” FG