It is recognised that getting cows back in calf efficiently is important for dairy farm profitability. Kingshay Dairy Costings (2019) compared the group average for all farms submitting data to them with the top performing 25% of that group:
While cows with higher annual yields, eg 10,000 litres, and more persistent lactation curves than above might have a lower cost per day of extended calving interval, there will still be a cost to sub-optimal fertility.
It is also well known that good dairy herd fertility depends on getting lots of things right, including cow nutrition. Cows that lose more body condition score (BCS) in the first 5 weeks post-calving have poorer fertility, as in the table below (Butler and Smith, 1989):
BCS loss acts as a measure of energy balance over a period of weeks. Other measures of energy balance and metabolism have shown an association between excessive negative energy balance (NEB), or subclinical ketosis, and poorer fertility. Raised BHB and/or raised NEFA in the first two weeks after calving were correlated with a 13-16% reduced chance of pregnancy (Ospina et al., 2010) and a 16-22 day increase in calving-conception interval (Walsh et al., 2007).
Feeding Glycal Forte® improves energy balance post-calving (see ‘Reduced weight-loss post-calving’) and also supplies bio-available calcium; subclinical hypocalcaemia has been associated with reduced feed intakes (Goff, 2008; Martinez et al., 2012). Feeding Glycal Forte® on commercial UK dairy farms has resulted in improvements in pregnancy rates, as shown below: