Wednesday, January 2, 2019

Large Variation in Starter Intake Observed

 Calf starter intake data were collected from 4,534 Holstein heifer calves at a Minnesota research facility. 

Two observations were of interest to me. 

One, there was a wide variation among calves in the amount of calf starter grain consumed in spite of the fact that they were all fed the same calf starter, the same amount of milk replacer and raised in the same environmental conditions (weather, air quality, barns, bedding, water availability and so on). 

During week six (weaned at 42 days) the average calf starter grain intake (sum of intake for 7 days) was 39 pounds (about 5.5 pounds per day). That is quite a respectable level of consumption.

However, the standard deviation was 17 pounds! Or, if we look at the population of 4,534 calves roughly 2/3rds of them had intakes between 22 and 56 pounds (between 3 and 8 pounds daily).

Calf management implications? The big eaters usually do fine - they sail through a change in housing (individual pens to group pack pens) and keep growing at a rapid rate.

But, what about the "picky" eaters? The ones that get to 49 days and are still only consuming 2 or 3 pounds of grain a day?

I had a "left-back" management program. These picky eaters were "left-back" in the individual housing for an extra week or even two before going to group housing. There was extra labor to keep them in the individual housing for one or two extra weeks but I considered that well worth the time not spent on treating sick heifers in the transition pens. I made this program work by marking the pens of the "picky" eaters so we could monitor their grain intakes - roughly five percent of my calves.

Second observation.

Their data showed a distinct seasonal effect on calf stater grain intake rates. Grain intakes were significantly higher for calves born in the fall and winter compared to spring and summer. It was nice to know that their experience was the same as mine.

 I was frustrated with the same effect with my own calves. I fussed and fussed with changing the grain in pails, made sure the calves had plenty of free-choice water from June through September (I was in a western New York State climate) with limited success - once the weather got hot grain intakes fell significantly below those during the cold weather months. The percentage of calves that had to spend an extra week or two in the individual housing always went up during the summer. Year after year, during hot weather the winter-time 56-day average daily gains dropped from over 2 pounds daily to 1.7-1.9 pounds per day.

Reference: Rauba, J. and Others, "Relationships between protein and energy consumed from milk replacer and starter and calf growth and first-lactation production of Holstein dairy cows." Journal of Dairy Science 102:301-310. January, 2019.

No comments: