Set calving targets to gauge herd performance
As the calving season kicks off for real on most spring calving dairy farms, it is important to set a couple of targets, or key performance indicators (KPIs) as they say in the world of business. How will your stock compare to the top 5pc of herds?
The first KPI is your calving interval. This is the period of time from one calving to the next. Are the same cows that calved in the first two weeks last year calving in the first two weeks this year? The national calving interval in Ireland is 400 days. This means, on average, that, nationally, cows are slipping over 30 days, or one month, for each lactation.
Are your heifers calving first to compensate for this slippage? If heifers calve in the first week of February this year, will they calve on March 1, 2012? Compare the calving date for a second-lactation cow that calved last year and see when she is due this year. What is her calving interval? Is she close to the national average or is she managing to calve within 375 days of her last calving?
This emphasises the importance of ensuring that all your first-calving heifers calve at the beginning of the season.
Your median calving date is your next KPI. This is the date when 50pc of your herd has calved. Looking at your records again, when will half of the herd be calved? Circle that date and count the days back to the start of calving. The target is to have 50pc of the herd calved in 21 days. How does your herd compare to this figure? If calving starts on February 1, at least half of the herd should be calved by February 22. A slow start with small numbers calving is not desirable.
One consequence of this will be lower milk solids, particularly protein in late spring when these figures should be starting to move upwards. Protein content is at its lowest six weeks post-calving, so not getting half the herd calved quickly will keep this figure low.
Cows calved in the first week of February will have their lowest protein around St Patrick's Day and then start to rise. A cow calved on March 20 will not hit her lowest protein until early May, keeping the protein low for the herd into late spring or early summer when it should be rising.