A New Study with Some Promising Results
In Alabama, properly developing beef replacement heifers is key to herd profitability. Getting heifers bred at 15-16 months and getting them rebred for their second calf should be a goal for every cow/calf producer.
Kent Stanford and Landon Marks, both Alabama Cooperative Extension System employees, wanted to demonstrate proper heifer development.
First, they needed a place to demonstrate heifer development and approached the Sand Mountain Research and Extension Station personnel. The Sand Mountain Station was a perfect place because both Stanford and Marks wanted to develop the heifers on grass and the Station had 55 acres of land that could produce stockpiled fescue and support planting rye and ryegrass cool-season annuals.
With Sand Mountain on board, Stanford and Marks then worked on finding area producers to consign heifers. By Dec. 1, 2015, they had found six area producers willing to send their best replacement prospects to Sand Mountain for 167 days.
In early January 2016, 48 heifers were delivered to SMREC. The goals were simple: have these heifers gain 1.75-2.25 lbs./day on winter grazing and be returned to their owners bred AI to a calving-ease, growth bull in June.
By the time the heifers arrived, there were 8 acres of stockpiled fescue, Texoma variety; 8 acres of rye, Abruzzi; and 39 acres ryegrass, Marshall, ready to graze. Texoma fescue is an endophyte-friendly variety of improved fescue.
The fescue stockpiling process began in August 2015 when the 8 acres was mowed and 60 pounds of nitrogen applied per acre.
In October 2015, the rye and ryegrass was drilled into sod and 50 pounds of nitrogen per acre was applied. These pastures received an additional 30 lbs. of nitrogen per acre in early March. Different forage types were made available to ensure forage was available from January through June. It was expected the stockpiled fescue and rye would provide adequate forage early, and that ryegrass would persist longer into June.
Heifers were rotationally grazed on these pastures. When heifers were put on each pasture, forage height was taken using a forage grazing stick. Heifers were left on the pasture until they grazed half the forage. They were then rotated to a different pasture. Table 1 provides the total amount of forage produced and consumed of each of the three types of forage.
Because the winter was mild, the rye and ryegrass pastures were actively growing throughout the development period. Heifers were rotated through each pasture several times ensuring the heifers ate half and left half of the available forage. It is also important to note that only 25 of the available 39 acres of ryegrass were grazed. Forage growth was such that 15 acres of ryegrass was not needed to support growth of these heifers. When heifers were on ryegrass pastures, they ate significantly more per day than on either fescue or rye pastures. It is known that cattle prefer the palatability of ryegrass more than fescue or rye.
Overall, heifers gained 1.88 lbs./day from January to June. Heifers, on average, weighed 618 pounds on delivery to SMREC and left weighing, on average, 907 pounds. The average weight per day of age was 1.82 lbs./day. WDA is calculated by dividing body weight by the age of the heifer, in days. The goal is to have ADG and WDA values close. WDA does include birth weight of the heifers. When ADG and WDA are similar, it indicates heifers have been on a steady growth plane since birth. Table 2 shows how forage intake increased as they got heavier throughout the demonstration.
Heifers were also measured for hip height in order to determine frame score. Frame score can then be used to predict mature weight of the heifer. On average, heifers were a frame score 5.6, equating to a 1,260-pound mature weight at 4-5 years of age. Additionally, carcass trait ultrasound measurements, reproductive tract scores and pelvic area measurements were taken. RTS values can help predict reproductive performance of yearling heifers, especially for pregnancy rates in synchronized breeding and pregnancy rates at the end of the breeding season. Scores are ranked from 1 (immature) through 5 (cycling). Pelvic area can provide an estimate of the maximum calf birth weight the heifer can deliver without assistance. In general, producers can take the pelvic area and divide by 2 to arrive at the birth weight that will not cause calving difficulty.
In early April, estrous in heifers was synchronized using a Select-Synch plus CIDR protocol. When the CIDR was removed after seven days, heifers were visually observed for standing heat. Those heifers in standing heat were AI bred 12 hours later. Heifers not observed in standing heat were bred AI 72 hours after removal of the CIDR. There were 34 heifers observed in standing heat and 14 heifers bred later. At the time of breeding, heifers were estimated to weigh 63.5 percent of their mature body weight, with a range of 52-75 percent. Heifers should weigh 65 percent of their estimated mature body weight at breeding. Ten days after heifers were bred AI, a cleanup bull was turned out. He remained with the heifers for 57 days.
A licensed veterinarian palpated the heifers to determine pregnancy. At the time of palpation, the veterinarian could only determine whether heifers were bred AI or had been bred in late April by the bull. It was determined 35 percent (17 heifers) were bred AI and another 35 percent were bred by the bull. Called open heifers will be rechecked for pregnancy in early August.
The goal was to have 68 percent of the heifers bred to the AI bull and an overall pregnancy rate of 90 percent. It is not entirely clear as to why more heifers did not become pregnant to the AI bull and only time will tell how many of the called open heifers are bred.
There were many successes in this inaugural year of the Sand Mountain Heifer Development Program. Heifers were developed only on forage and minerals from January through June. Cost of grazing (seed, herbicide, lime and fertilizer) was $99.50/heifer or $86.84/acre. Heifers remained healthy throughout the program with only routine vaccinations, deworming and fly control needed. Most importantly, according to Marks and Stanford, management practices were performed that could be performed by any cow/calf producer in northeast Alabama on their own farm.
The Time to Stockpile Forages in Alabama is August
To have stockpiled forages for winter months, August is the time to start stockpiling. Both fescue and Bermudagrass can be stockpiled successfully to be used in late November through February. To effectively stockpile forage:
For fescue stockpiling, it is best to use an endophyte-free or endophyte-friendly variety. KY-31 fescue that contains the harmful endophyte will contain high concentrations of the harmful endophyte when stockpiled.