Is body condition loss affecting cow fertility?

Ulster Farmers' Union - dairy cows at Greenmout Agricultural College. Picture: Cliff Donaldson
Ulster Farmers' Union - dairy cows at Greenmout Agricultural College. Picture: Cliff Donaldson

The main goal for spring-calving dairy producers is to calve their cows with minimal issues to ensure they are primed to go back in calf as soon as possible.

A key management factor that influences this is body condition scoring (BCS) and the aim is to calve cows at the correct BCS of 3. If cows are too thin at calving (<2.75 BCS), peak milk yields can be reduced and reproduction can be compromised. Whereas, if cows are too fat at calving (> 3.25 BCS), they are more likely to incur issues such as milk fever, retained placenta, ketosis and uterine infections. These issues can in turn have a seriously negative effect on reproduction performance and can prove very costly.

Even when cows calve down in the correct BCS of 3, they still face many challenges that can compromise successful breeding. In early lactation, the cows dry matter intake (DMI) is reduced. This DMI decline begins about two weeks before calving and continues for several weeks after calving. In this period, the cow’s energy requirement is higher than the amount of energy that she can consume - this energy deficit is called negative energy balance (NEB). Due to the NEB, the cow mobilises body fat reserves and loses body condition. After calving, the magnitude of NEB increases because her DMI lags behind the energy required for the rapid increase in milk yield. The higher yielding cow will mobilise more body fat for a longer period of time compared to a lower yielding cow. In early lactation, depending on the severity of the NEB, a cow can lose as much as 0.7kg of bodyweight per day. It goes without saying that this bodyweight loss is a major nutritional factor affecting fertility performance.

Research has shown that when excessive BCS loss occurs, first ovulation after calving is delayed, conception rates decline and days open increase. Poor fertility performance represents significant costs and research from Shalloo et al., 2014 highlighted that an improved six-week calving rate could be worth over €26,000 (£20,000) for a 100 cow herd. In order to achieve improved target calving rates, dairy producers must strive to optimise DMI and energy intake for cows throughout the transition period to minimise the level and duration of NEB and BCS loss during early lactation. All cows will suffer from NEB and will lose BCS to some degree, but this loss should be kept to a maximum of 0.5 BCS.

Research carried out at University College Dublin (UCD) on the Alltech® yeast technology, YEA-SACC®, has shown benefits in terms of overcoming excessive loss of body condition and subsequent fertility problems. This trial work which was carried out on a grass-based situation, showed that YEA-SACC created a more stable rumen (stomach) environment by significantly improving rumen pH, which allows for improved feed and grass utilisation. This was reflected in the results with a significant increase in energy (volatile fatty acids (VFAs)) coming from the rumen when cows were fed YEA-SACC. The trial also highlighted that YEA-SACC fed animals mobilised less body fat reserves (non-esterified fatty acids (NEFAs)), an indication that cows were retaining better body condition.

In summary, the goal of early lactation feeding is to maximise feed and grass utilisation in order to increase dry matter intake as soon as possible after calving, this will in turn help to minimise body condition loss and improve fertility performance.

Trial work carried out using YEA-SACC at UCD and other leading dairy research centres have shown these benefits to be specific to YEA-SACC as not all yeasts are capable of such significant improvements - ensure you choose the proven technology.

Contact your feed supplier or Richard Dudgeon, technical adviser at Alltech on +44 7739 745379