Thursday, July 5, 2018

Weaning Readiness: Is it the daily calf starter intake level or the total amount of calf starter consumed?

A research team measured efficiency of digestion of calf starter grain (CSG) post-weaning. Efficiency of digestion was used as a measure of weaning readiness. Daily calf starter intakes as well as total amounts of starter consumed up to weaning were recorded.

The calves varied widely on daily calf starter intake levels beginning at three weeks of age - this was related directly to the volume of milk replacer (MR) consumed - one-half of the calves received about 1.5 lbs. of replacer powder daily while the other half was fed 2.4 lbs. daily.

These two different milk replacer feeding rates resulted in the moderate MR calves averaging 1.8# daily calf starter eaten and high MR calves consuming only 0.5#/day at day 42 when their milk replacer rations were cut in half. Then, they were both weaned at 49 days regardless of daily calf stater intake level.

By day 56 calf starter intakes accelerated up to 4.2#/day and 3.5#/day respectively for moderate MR and high MR feeding groups.

So, what did the efficiency of digestion numbers look like?

Calves that began eating calf starter grain (CSG) at a younger age and ate more total CSG had slightly higher levels of digestive efficiency at 8 weeks of age. [CSG was in pelleted form]

As I read the data reported in the research article it looks like both length of time eating CSG and total volume consumed contribute to desirable feed conversion rates in our weaned calves.

In practical terms, if larger volumes of milk/milk replacer are fed extra care needs to be taken to ease these calves into 100% dependence on CSG at weaning time. A good three weeks of at least 0.5#/day CSG may be a workable rule of thumb to observe before withdrawing all milk. Cutting the milk ration in half around 35 days nearly always results in an accelerated rate of CSG intake. These data suggest a full week at 3.5 - 4.5#/day CSG consumption is desirable at the time of full milk withdrawal.

Just a note from a recent experience, be sure to check that CSG contains some kind of coccidiostat - saving money by leaving it out of a CSG is ill advised. Weaning is always a stressful time and coccidia always take advantage of stress events to hammer our transition heifers.

Remember, also, at weaning to introduce hay slowly over a period of 2 or more weeks in order to allow time for the rumen microbial population to multiply enough to effectively digest this fiber. Abrupt introduction of "free-choice" hay is associated with weight loss, pneumonia outbreaks and coccidiosis.

Reference: Quigley, J.D. and Others, " Effects of feeding milk replacer at 2 rates with pelleted, low starch or texturized, high-starch starters on calf performance and digestion." Journal of Dairy Science 101:5937-5948. June 2018.

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