LEADING dairy experts from the UK and Europe took to the stage at Dumfries House in Ayrshire, last month for Mole Valley Farmers' National Dairy Conference entitled Fertility: Challenges and Latest Solutions.

With fertility forming the linchpin to the success of any dairy business, Dr John Cook, global technician for World Wide Sires, warned that it along with nutrition and health in the transition period, are key to improving the health, productivity and longevity of UK dairy cows, which on average result in 34%-50% of fresh-calved cows having at least one form of reproductive tract disease between week three to week seven post-partum.

Furthermore he said that some 5-20% experience metritis problems; 5-20% experience PVD, while 10-30% experience endometritis, and 44% of milking cows can be considered unhealthy in the first 60-days of production – the critical period for any dairy cow.

“Dry cows need to be fed correctly for 21 days pre calving to avoid health problems both during and after calving," said Dr Cook, adding that such animals also require adequate feed access and trough space to reduce the risk of bullying.

"Other management concerns relate to the risk of milk fever risk and include cow comfort – animals should have access to calving and isolation pens with fresh water and adequate trough space.

“Dry cow groups should be as stress-free as possible, and this requires minimising group movement to prevent social order changes. Cows will have to deal with changes and close-up calving cows should not have to compete for feed on the basis of cow rank. It is also important that dry cows are kept on clean, dry bedding as wet bedding allows the movement of bugs that can travel from cow to cow."

Dr Cook who is a former partner in the Cumbria-based Paragon Vet Group, added that nutrition and diet formulation throughout the dry cow period are essential to prevent milk-fever concerns and that such cows should also be housed on a solid bedding such as deep straw or sand and have access to good ventilation and lighting.

A good transition period helps bolster fertility too according to Dr Jo Leroy from The University of Antwerp's department of veterinary science in Belgium, who urged farmers to set optimal health and fertility targets.

“Farmers have to have an end product to reproduction and that starts with a healthy new-born calf. This has to happen every year to keep the cow in the herd. Farmers need to focus on the key areas of the lactation cycle, understand the risk factors involved and the delivery of optimal fertility.

“The calf also has to have genetic gain as she is the producer of the future. In a metabolically healthy cow, farmers have to establish critical limits; establish monitoring procedures and establish the correct actions to take place. This includes record keeping and verification procedures; conduct a hazard analysis and identify the critical control points,” added Dr Leroy.

The cornerstone of modern dairying includes milk yield; replacement heifers, cost efficiency, longevity and sustainability as well as, environmental pressure that are all critical to farmer income. The sensitive issues involve heifer rearing, metabolic pressure and disease, inadequate housing and social stress suboptimal management and nutrition.

Hence, farmers need to question whether the cow is adapted to the management – and is the management adapted to the cow. This includes the housing environment, social order and, if the cow has access to the correct feed.

“There should not be a negative energy balance. Dry matter intake and energy intake depends on when a cow can eat; when she eats and what she eats,” he said.

“Metabolic energy priority requires energy availability in the body and cows must be able to eat and have an appetite. She has to be healthy, able to walk to available feed and be competitive. The feed has to be digestible; fresh, have the correct composition and quantity. Cows have to have the correct body-condition and that begins with dry cow management.

“We have to feed her for fertility before she calves down and feed for optimal liver health. This also includes feeding for ovarian activity due in the first few week’s post-partum and for optimum oocyte and embryo quality. Healthy cows will produce a lot of milk – and be fertile. However, the modern dairy cow needs our support,” concluded Dr Leroy.

However, following the hot summer of 2018, which saw drought conditions and a significant decline in grass quality and quantity, Dr Robin Hawkey, senior nutritionist at Mole Valley Farmers said precision nutrition and fertility requires a combination of many factors this year.

“The rapid forage decline started in June as a result of the warm weather conditions. Following a 70kg of Dry Matter per hectare per day peak period, production slipped down to 20kgDM/ha/day in August. Cows also suffered from heat stress due to the prolonged hot conditions which may have resulted in reduced milk yields as well as decline in levels of fertility.”

Dr Hawkey explained the link between body condition, lameness and fertility, with research showing a link between an animal’s hoof-fat pad and conditions of lameness. Poor hoof-fat pad condition, he said, can cause lameness in cows, and if the animal cannot eat or graze properly due to lameness, the cow will enter negative energy balance. This results in the cow having fertility issues; not having an oestrus-cycle and therefore not being inseminated at the correct time, due to not showing any signs of heat-cycle.

Due to loss of body condition, the cow will then suffer decline in levels of milk production and may require veterinarian treatment or hoof-trimming.

“Energy balance is crucial to overall animal health and welfare and is dependent on presentation; energy type as well as, dry cow transition management. It's important farmers appreciate the importance of wider issues in fertility management, ration construction and balancing,” he concluded.

And, contrary to popular opinion, Dr Tom Chamberlain, MRCVS, Chalcombe Limited, stated high milk yields need not cause long-calving intervals and most dairy farms can improve calving intervals.

“The lower the calving-interval the better,” he stated. “The cost of an extended calving-interval can be between £2 to £3 per day and farmers should know their own figures.

“A 370-day calving-interval is excellent; 380-days is good and a 400-day calving-interval is acceptable. Extended calving-interval is one of the biggest inefficiencies on farm and farmers should set targets requiring a strict VWP as well as first-service submission rates. The biggest on-farm problem is a lack of time, not a lack of expertise.

“There are various on-farm actions to help reduce calving interval such as conception-rates. Farmers may have to accept lower conception rates to get a better calving interval. However, conception-rates are not the biggest problem on-farm – the bigger problem is not getting cows served and animals need to be identified and served earlier.”

Dr Chamberlain added that there are numerous benefits and costs of targeting shorter calving intervals such as more calves being born and increasing number of calf sales. An increased number of pregnant cows also reduces enforced culling of cow numbers and results in better cow selection, with more heifers born providing sufficient replacement animals and better genetic selection.

Rate of milk yield decline is also a factor and heifers decline slower than cow yields. Decline could be due to having different fertility criteria or feed management differential with some herds being fed on a TMR diet. There are financial benefits over a cow’s lifetime between a 365-day interval compared to 450-day interval. Over a four-lactation period shorter calving interval will produce 1755litres worth £526 (based at 30ppl).

Hence, he said farmers should not serve cows after 200-days in milk to avoid getting too many stragglers; and should stop serving cows when enough animals are in calf. In addition, he said animals should not be served producing below the herd average milk yield and that farmers should avoid milking cows yielding less than 40% of peak yield.

Immune system and fertility

Results from 29 farms in the Netherlands using OmniGen-AF demonstrated a 34% reduction in the use of antibiotic treatments according to Arnout Dekker, marketing manager for Philbro Animal Health in Europe.

The field-trials took place over a six-month period and involved 5555 dairy cows with the information supplied from MediRund, the official data-base in The Netherlands.

According to Dr Dekker, the effects of stress on dairy cows is well documented especially on those animals at the start of lactation but studies have shown incorporating OmniGen-AF in the diet supports the immune system resulting in reduced cases of mastitis; metritis and lower somatic cell counts. The product is recommended to be fed to dry, pre-fresh and lactating cows on a daily-basis to help support an animal’s immune system.

He added that research has shown the stress-hormone cortisol, is closely associated with an animal’s reduced level of immune cell function. When an animal is in a stress condition, neutrophils, a type of immune cell, becomes compromised and this reduces its ability to identify and enter the tissues being affected by pathogens.

“Philbro research has demonstrated significant improvements in innate immune function, herd health and production. We recommend OmniGen-AF to be fed to dry cows as well as lactating cows at a rate of 56grams per day. OmniGen-AF takes 45 to 60-days to become fully effective within a cow’s metabolism and takes five to seven days to lose the effects.”

Several events that contribute to elevated stress levels in dairy cows include calving; drying-off, forage and feed quality, high milk production, housing and pen challenges, stocking density and weather conditions. Short-term or unexpected challenges can present sudden increases in stress levels including sudden changes in temperature and humidity, herd over-crowding and disruption to feed quality.

Trial work in the US on 787 farms, involving 473,711 cows between 2007 to 2015 provided positive results over a 90-day period. The immunity challenge demonstrated a 20% improvement in health events over the trial period. The challenged events included mastitis; metritis, ketosis, retained placenta, abortions, hospitalisation and death-loss.

2018 UK dairy farm immunity challenge results involving 3,560 cows on 15 dairy farms demonstrated evidence of improved immunity. Mastitis cases per 100 cows was reduced by 37.4%; with decreases in metritis, retained placenta, abortions, and lameness down by 15.2%, 35.6%, and 35%, respectively. Drug expenditure was down 35.3% and return on investment on the 15 trial farms had a ratio of 3:1.

“OmniGen is used in the best dairies in the world with over 3,300,000 cows receiving the product,” said Mr Dekker. “There has been 17 years of research with 400 field-trials involving over 500,000 cattle. The results can be measured by blood-testing procedures. The product provides a unique opportunity to reduce antibiotic usage.

“The trials clearly demonstrate OmniGen-AF strengthens the immune response to pathogen challenge, especially during periods of immune suppression or dysfunction. The results on farms worldwide demonstrate better animal health; better fertility and more efficient milk production. Furthermore, the results have proven to be consistent,” he concluded.