What's Going On In Calf Research Today?
Posted: August 4, 2006
We recently attended the annual meeting of the American Dairy Science Association, where many scientists from around the world presented the newest information from current research projects. Here is a summary of some of the new and interesting findings that affect calf health, feeding, and management.
Researchers from Minnesota (Carrier et al.) investigated factors that affect the number of stillborn calves in a commercial herd. Twin births were not included in the study, and a total of 495 calvings were analyzed. Results showed that cows requiring slight assistance with calving (calving difficulty score of 2 on a 5-point scale) were 2.9 times more likely to have a stillborn calf than cows that delivered unassisted.
Stillbirth was 46 times more likely for cows with a calving difficulty score of 3 or more compared to cows that did not require assistance. Heifers were 5.2 times more likely than cows to have a stillborn calf. These results are from a single herd, but they demonstrate that any type of assisted delivery increases risk to the calf. Take steps to reduce this risk by training employees to quickly recognize heifers or cows that need assistance and to provide that assistance properly. Other results of this study showed that cows moved from freestalls to an individual calving pen when the water bag or feet/head were showing were 2.5 times less likely to have stillborn calves than cows moved while only mucus or blood were showing.
Other Minnesota research (Hagman et al.) looked at the level of passive transfer in calves fed pasteurized colostrum. Colostrum was pasteurized using a low temperature, long time method that lab tests showed preserved colostrum IgG and killed pathogens. Fresh colostrum was split in two equal samples of 1 to 2 gallons. One sample was refrigerated; the other was pasteurized at 140°F for 60 minutes, then refrigerated.
Newborn calves were fed 1 gallon of either raw or pasteurized colostrum by esophageal feeder within 2 hours of birth. At 24 hours of age, total protein and IgG in the calves’ serum were higher for the calves fed pasteurized colostrum than for calves fed raw colostrum (serum IgG was 22 g/L and 18 g/L for calves fed pasteurized and raw colostrum respectively). Researchers did not report the concentration of bacteria in colostrum before feeding, but suggested that pasteurization reduced the number of bacteria enough to give IgG a competitive edge in absorption across the immature intestine.
Cornell researchers (Grusenmeyer et al.) reported that cows given a short dry period (40 days) produced less colostrum than cows given a 60-day dry period (20 versus 15 pounds of colostrum for 60-d and 40-d dry periods respectively). Colostrum IgG was not affected by dry period length and averaged 77 g/L for all 334 cows in the study.
A survey of 55 colostrum samples from Pennsylvania dairy farms (Kehoe et al.) found an average standard plate count of over 997,000 colony forming units/ml (cfu/ml), with 38 percent of samples exceeding the oft cited goal of 100,000 cfu/ml or fewer. Standard plate count is an indication of the total bacterial contamination in a sample.
In addition, coliform counts, which reflect contamination from manure, averaged over 323,000 cfu/ml in the study. A goal for coliform bacteria is 10,000 cfu/ml or fewer; 33 percent of samples failed to meet this target. These results suggest that many farms have an opportunity to improve colostrum quality. Collect colostrum from clean, dry udders and chill or feed it immediately after collection. When storing colostrum in the refrigerator, put it in 2- to 4-quart containers to cool it rapidly. Finally, thoroughly clean and sanitize all colostrum collection and storage equipment after each use to prevent bacterial growth in milk residue.
Waste Milk Pasteurization
Virginia Tech researchers (Scott et al.) investigated waste milk pasteurization on 3 North Carolina farms. Before being pasteurized, milk had an average standard plate count of 17.3 million cfu/ml. After pasteurization, the count dropped to 450,000 cfu/ml, which is considerably higher than a goal of 20,000 cfu/ml after pasteurizing. The study found that 2 of the farms periodically experienced incomplete pasteurization (evidenced by the presence of alkaline phosphatase in 18 and 15 percent of heat-treated milk samples).
Not surprisingly, bacteria counts in this milk were quite high (348,000 and 5.3 million cfu/ml); however, on these farms bacteria counts were also high (64,000 and 367,000 cfu/ml) when pasteurization worked (no alkaline phosphatase present). This was primarily due to the very high bacteria counts before pasteurization. Researchers also tested milk at the next step – feeding it to calves.
At the beginning of feeding, the standard plate count was 2.4 million cfu/ml. By the end of feeding, 1 hour later, counts reached 10 million cfu/ml. This work provides an excellent reminder that pasteurization is not sterilization. It is impossible to reduce bacteria counts to an acceptable level if we start with the kind of contamination observed in this report. In addition, strict attention must be paid to cleaning and operation of pasteurization and milk storage equipment to achieve satisfactory results.
Curious about the bacteria levels in milk or colostrum you are feeding to calves? Talk to your veterinarian or milk company to see if they will run a standard plate count. Some suggested sampling times are: immediately after milking, before and after pasteurization, and just before feeding calves. Be sure to keep samples refrigerated if they must be stored before testing.
Enhanced Feeding and Immunity
Iowa State and USDA researchers (Foote et al.) reported that calf growth rate had little effect on adaptive immune functions. Calves fed at maintenance (0.24 lb gain/d) or for gain of 1.3 lb/d or 2.6 lb/d generally responded similarly to vaccination, with no improvement in calves fed for greater gain.
In fact, calves gaining at the highest rate had fewer mononuclear leukocytes than the other calves, and helper T-cells in these enhanced-fed calves failed to increase with age. Also in the calves growing at the highest rate, the response of T-cells to an antigen challenge was lower than that of other calves. These results suggest that very high growth rates may suppress some aspects of the immune system and put calves at greater risk for disease.
Long Term Effects of Accelerated Milk Replacer Feeding
Researchers at Michigan State University (Davis Rincker et al.) studied the effects of an intensified compared to a moderate milk replacer feeding program on long term growth, age at calving, and milk production. They fed a standard 20-20 milk replacer fed at 1.2 percent of bodyweight compared to a 30 percent protein, 15 percent fat milk replacer fed at 2.1 percent of bodyweight to 80 heifers (40 each group) until 6 weeks of age. They then followed these calves monthly until calving and summarized their data through the first 150 days of first lactation.
The intensively raised group calved 17 days earlier and at calving both groups had the same body weights, withers height, body condition scores, calving difficulty scores, calf weight, and 150-day milk production. Their results showed calf feed costs were $49 higher for the intensively fed group; total pre-weaning costs were increased by $41. The final net present value of the intensively raised animals was decreased by $21, and conventionally raised calves were more economical overall.
Two trials investigating protein in calf starter were presented by scientists from the Akey Inc. calf research facility in Ohio (Hill et al.). In the first study, 48 Holstein calves were fed 1.5 pounds of milk replacer containing 26 percent protein and 17 percent fat and were weaned at 28 days. Calves were offered a pelleted starter that contained either 18 or 21 percent crude protein. Calves gained about 1.2 pounds per day. Weight gain, feed efficiency, and starter consumption were similar for all calves regardless of starter protein content.
The second study was similar, but starter offered was 18 percent crude protein and contained either a low or high amount of undegradable protein. The highly undegradable protein starter included Soyplus ®. As in the first trial, calves gained about 1.2 pounds per day. Weight gain, feed efficiency, and starter consumption were similar for all calves regardless of the amount of undegradable protein in starter. These data add to a large body of evidence that calf starter protein content in excess of 18 percent is not necessary and that alterations in the rumen degradable and undegradable protein fractions do not improve performance of milk-fed calves.
- Coleen Jones, Dairy and Animal Science Research Associate, and Jud Heinrichs, Professor of Dairy and Animal Science
- Department of Dairy and Animal Science