Thursday, February 16, 2017

Do All Preweaned Calves Have the Same
Pattern of Eating Concentrates?
(aka Calf Starter Grain)

I was searching today for information on automatic calf feeders and weaning. I ran across at bit of information that shows how much preweaned calves vary  in their patterns of consuming concentrates (calf starter grain).

The method of measuring concentrate intake was simply a computer-controlled concentrate feeder that recorded weights of grain eaten at every meal by every preweaned calf.

One treatment in the research trial was to decrease the amount of milk fed based on the volume of concentrate eaten. They set these thresholds for initiating decreases in milk fed:
     First step:    calves eat 200g/d (0.4 lbs.) daily for 3 days in a row, drop milk from 12 L to 9 L per day.
     Second step: calves eat 600g/d (1.3 lbs.) daily for 3 days in a row, drop milk from 9 L to 6 L per day.
     Third step:     calves eat 1,000g/d (2.2 lbs.) daily for 3 days in a row, drop milk from 6 L to 3 L per day. 
    Fourth step:    calves eat 1,400g/d (3.1 lbs.) daily for 3 days in a row, drop milk from 3 L to 0 L per day.

Now here is the interesting part!

The age at the first step down (from 12 L to 9 L per day) averaged 55 days. The full range was from 23 to 82 days.  Wow! That said, two-thirds of the calves fell in the range of 35 to 75 days - that's still a pretty wide spread.

What do I think these data have to do with day-to-day calf management?

1. If the goals of a weaning program is to minimize post-weaning illness and to maintain rates of daily gains then we should take into account the wide variation among calves in their willingness or ability to each concentrates. When weaning for calves fed a maximum of 12 L per day was tied to solid feed intake the earliest calves in this research trial were fully weaned at 56 days and the latest were fully weaned at 91 days.

2. Some provision may be needed for the "late weaners." When I was raising calves I called them the "left-back" calves. Eighty or ninety percent of my calves moved out of my hutches at 56 to 63 days - but there were those slow weaners that were "left-back." I had a row of hutches where I could stick these "left-back" calves for a week or two until their calf starter grain intakes improved enough to be moved into a transition pen with the next batch of calves. 

3. Lock-Step weaning (all the calves are weaned at the same age) may have hidden costs. The laggards (the ones that are slow to increase their concentrate intake) may need to be treated at a rate much higher than the "average" calves. And, if a weaned pen has several laggards that get sick they may infect the entire pen.

4. What holds us back from weaning based on starter intake? In my experience the major negative factor is monitoring calf starter grain or concentrate intakes. It takes little skill and effort to just dump some grain into a feeding pail (especially when it is kept one-half or two-thirds full). Compare this to frequent dumping of grain pails (even daily during hot humid summer months) and feeding a volume just a little bit greater than daily intakes.

This latter approach assumes the skill and  interest on the calf care person to actually observe individual calf intakes. Well, I actually fed about the same amount of grain to entire groups of calves based on age only watching for the exceptions to the rule. Probably one calf out of  eight or ten needed special attention - I usually flagged their pen to remind myself and others that this calf was an exception on grain feeding. 

Reference: Passille, A. M. and J. Rushen, "Using automatic feeders to wean calves fed large amount of milk according to their ability to eat solid feed." Journal of Dairy Science 99:3578-3583 May 2016.




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