Vet Chris Watson gives us some pointers on ensuring we have enough heifer replacements coming through the system and at the right time
Last year I pointed out the blunt truth that the UK dairy industry is probably not self- sufficient in replacement heifers, or at least not within an economic period of time. After all anyone can rear heifers eventually, but eventually is not good enough.
The average dairy herd with a normal mixture of beef and replacement breed inseminations is only producing a total of 56 live calves per 100 cows in the herd during the 12 months after calving. Allowing for males and beef calves, this amounts to 24 heifer replacement calves per year per 100 cows. And that is before the rearing losses.
We are currently launching a series of initiatives in the practice to address the wastage and shortfall in heifer output from dairy herds. The starting point is with an audit of your own herd.
Look at the herd replacement rate and the number of home-reared heifers brought into the herd each year and compare that with the number of cows calving and how many replacements you need. The next step is to look at the key areas of loss.
Step 1: Ask yourself what are the management choices about breeding policy, and what are the fertility losses determining how many cows get pregnant? Both affect the number of heifers actually born per year. Half of all the total loss is due to poor fertility and getting cows back in calf to calve within a 12-month period.
Step 2: Then look at heifer rearing. There are two clear issues here – disease losses and rearing performance. Check the rearing policy to look at losses from birth to actually calving back into the herd. How many make it and how long do they take to do so? Some workers estimate 14% of heifers born do not make it back into the herd due to disease and infertility.
Check your losses against those set out in Table 1. The herd range emphasises not just the scale of losses which can occur, but also that some farms are extremely good at controlling disease. So it can be done.
source: RVC 2011, 19 farmns, 509 heifers
But it is not simply just good enough to keep the animals alive, though that certainly helps. The rearing performance is a vital part of the economic success and can be huge influence as can be seen below.
Even a small delay to 26 months produces significant differences in performance.
Heifers need to be grown at a good steady rate (average 0.75kg/day) to breed at 15 months and calve at two years. It is no use looking back at the rearing process and seeing it fail its targets. You can, and must, spot the replace- ment heifers which are not going to calve at 24 months as early as one month of age. (See targets panel).
Because the growth rate in the early months is absolutely vital, it pays to put in place a simple monitoring system to check it and still have time to make changes.
Weighing the calf at key stages can be an effort but it is a simple method to check the system is produc- ing the right results.
We are working with a simple weigh cell system and calf crush to monitor calves and encourage farms to collect this essential data. You could also use a simple girth band and get some useful guidance about growth rate that way.
Our aim in the practice is to work with farms and draw up a management program for heifer rearing with precise monitoring to be able to offer timely advice so we can achieve the desired results.
1. Assess herd performance – how many homebred heifers calve per year as a percentage of cows calving?
2. Measure mortality rates at key stages:
1. Monitor growth rates – aim for 0.75kg per day overall and adjust before breeding
2. Identify the main problem areas for losses and poor growth rate: