Mature pen bucks lost a fifth of their weight with feed always available

STEP 1 · Ribs in December

Mature Brookings males gave up a fifth of October weight while intake fell

Monteith and colleagues took weekly weights on hand-raised white-tailed bucks at those pens. Trials took place in 2006 to 2008 and a second time in 2010 to 2011. The paper appears in Frontiers in Ecology and Evolution. The adult class held 12 males and none were younger than 4.5 years. The mid-October mean stood at 256 pounds (116.24 kg). Body mass by mid-December was 20 percent lower. That loss equals 52 pounds (23.5 kg). Ingesta-free body fat fell 31 percent. The fat change was 5.3 percentage points.

Yearling males in the pens lost less than those adults. The abstract reports yearling body-mass loss of 12 percent. About 20.5 pounds (9.3 kg) came off in that loss. Yearling body fat fell 22 percent. The change was 4.7 percentage points.

Feed and water never ran out. Weekday trials kept each buck alone inside a stall near 4 feet by 8 feet (1.22 by 2.44 m). Each morning included at least one hour with does inside a pen larger than 280 m2. Our arithmetic sizes that pen at about 3,000 square feet. Our read is that the loss is mostly a choice to eat less. There was little space for a long chase.

Body fat was estimated only in 2010 and 2011. Mule deer supplied the equation. Everything here comes from one station and from pens that were small. A wild herd facing a hard winter is outside this sample.

Pooled across groups, the shift between mid-October and mid-December followed starting mass at an r2 of 0.68. In the peak weeks adult males lost more than 8.8 pounds of body mass each week (more than 4 kg). Weekly loss ran about 4 percent. Of 22 females, 86 percent of the matings came during weeks 45 to 47. Standing estrus averaged 12 November.

STEP 2 · Missed meals

Metabolic-scale intake for adult bucks fell 56 percent at the peak

Those bucks reduced intake on their own. Mean dry matter intake showed about a 33 percent reduction in the weeks when female estrus peaked. That figure is one pooled week effect. The paper does not assign 33 percent to each male group separately.

Intake moved from 42.2 g per kg metabolic body mass each day at mid-October to 18.5 g per kg in the peak week of mid-November. The 56 percent decline is our arithmetic.

In the peak week, adults consumed 52 percent as much as the yearling males. Through the rut, yearlings ate nearly double the adult rate for their metabolic mass. Yearlings with an adult buck in the pen had the same intake and the same mass loss as yearlings without one.

During the mid-October week of blood sampling, intake and serum testosterone moved against each other at an r2 of 0.31. Monteith and colleagues see a risk-sensitive draw on reserves that were already stored. This loss showed up with the trough full and with too little pen for a long chase. Extending a 20 percent loss to every wild buck goes past the evidence.

STEP 3 · After the peak

Young southern bucks kept losing weight through March on free-choice pellets

Fowler, Newsom and Short kept ten white-tailed deer for two winters at Louisiana State University in Baton Rouge. Half were bucks and half were does. A pelleted ration stayed available at will across 18 months. The pellet protein minimum was 13.0 percent. Once each week the crew recorded weight to the nearest pound.

October 1966 brought an average buck weight of 141 pounds (64 kg). The February buck average was 126 pounds (58 kg). Bucks averaged a 10 percent loss. Does averaged a 3 percent loss. No deer in the trial was permitted to breed.

A single buck was down 16 percent in body weight. Buck intake reached its November low.

Eating less is why the weight came off in both pens even though food was still there. For the Louisiana bucks the low in intake arrived in November, and weight kept falling through March.

The authors write that sexually mature captive deer failed to hold weight in winter. A balanced ration was available at will the whole time. They link the voluntary intake drop to the sex cycle. These were young southern deer in a first adult rut. They differ from the older South Dakota males.

STEP 4 · Stomach volumes

Corn dominated Kansas winter volume while Southeast twigs stayed minor

A winter stomach shows foods deer located and swallowed. Menu rank and stand choice are separate claims.

Watt, Miller and Robel placed the 1967 paper in the Transactions of the Kansas Academy of Science. It covers 88 road-killed white-tailed deer from northeastern Kansas. Collectors started in May 1963 and stopped in July 1966.

Winter months were December through February. That season's sample was 21 deer. Winter volume from corn grain and cob was 34.0 percent. Coralberry fruit was 19.7 percent of that volume. Green winter wheat was 13.4 percent. Farm crops made up 57.2 percent within the winter total. Woody plants made up 38.9 percent within the winter total. Ages and sexes were mixed.

Harlow and Hooper summarized rumen work from the USDA Forest Service Southeastern Forest Experiment Station in Blacksburg. The total was 956 white-tailed deer rumens. Sampling used 32 sites inside 20 study areas. Coverage took in the Appalachians, the Piedmont and the Coastal Plain. The years were 1967 to 1970.

Over the full year, hardened woody twigs were the least frequent food category and the smallest by volume. Leaves still green on woody plants led both frequency and volume. Combined forbs, grasses, sedges, fungi and dry leaves made 35.9 percent of yearly volume. That matched the yearly share from those same green leaves.

Winter collections numbered 80 rumens in the Southern Appalachians, 46 in the Piedmont and 33 on the Coastal Plain. Twigs that had hardened showed up more in winter than in any other season. Harlow and Hooper still did not treat them as a major food. Winter abundance in their writeup included fruits, dry leaves, woody green leaves, and grasses and sedges. Every province had abundant acorns. Greenbrier and honeysuckle were among the green leaves listed for winter.

Vandeloecht, Pierce and Flinn wrote the University of Missouri Extension nutrition guide g9487. Adults at maintenance are given a protein range of 6 to 10 percent. Winter deer are described as needing little protein in quantity. In winter the guide has deer choosing foods rich in energy before foods high in protein. Acorns are charted with protein of 5 to 7 percent. Corn is charted with protein of 5 to 8 percent. Acorns and grain crops are called high in carbohydrates. Native plants for the winter diet are covered in more depth in our browse guide.

STEP 5 · Field rule

Sit the best remaining energy food for a short last-light bite

A standing corn block changes where deer take the last bite. Our corn guide treats the move off a standing block. It covers spilled grain and the brief window after the field is cut.

For a late-season hunt we sit the highest-energy food we can still find. That sit is our field rule. No cited study timed a wild feeding bout. Foods on that list are standing grain or spilled grain, acorns left on the ground, coralberry fruit, and green leaves on greenbrier or honeysuckle.

A buck with intake already cut is a weak bet for wandering bare twigs in the middle of the day. Corn led winter volume in the Kansas stomachs. In the Southeast winter sample, grasses joined acorns and dry leaves and green leaves as abundant foods.

The Brookings adults show a buck can stand about a fifth under his October mass and still refuse to fill up. On several late sits write down the time the first deer feeds and the sign left on that food. Count kernels, fresh acorn caps and nipped green stems. Skip twigs clipped bare with no green leaf left. Where feeding is limited to last light, keep the evening and drop the hours around noon. When the food is gone, move to a patch that still holds grain or mast or green leaves.

Season rules vary by state. Read the current official page your state wildlife agency posts before a late-season hunt.