Buckeye Dairy News : Volume 1 Issue 6

  1. First Harvest of Forages is Just Around the Corner!

    Mark Sulc & Thomas E. Noyes

    The first harvest of forage crops is just around the corner, in fact orchardgrass for dairy cattle will be ready for harvest in the southern part of the state as soon as fields dry out, if it isn't ready already. First harvest of forage crops and planting of row crops will probably be in conflict this spring. This is a tough choice to make, but for dairy farmers high quality forage is essential, and should be given priority over row crop planting, especially if the row crop to be planted is silage corn.

    The optimal time of harvest depends on your forage quality goals. Harvest in the boot stage for high quality orchardgrass, ryegrass, tall fescue, and reed canarygrass. Timothy and bromegrass harvest should be delayed to the early heading stage, because they are not very tolerant of cutting in the pre-heading stages.

    For pure stands of alfalfa, we can estimate the quality of the standing forage, and base the optimal timing of harvest on that estimate Fiber concentration, particularly neutral detergent fiber (NDF) content, is the primary variable of concern when evaluating quality of alfalfa for use by ruminant animals.

    On May 1st, the estimated NDF content of alfalfa was 32.4% at Columbus, 32% 
    near Millersberg, and about 29% northeast of Wooster in Wayne county. Last spring, alfalfa did not reach 32% at Columbus until May 20, so alfalfa development this year is well ahead of 1997 (this should come as no surprise, given the early spring this year). The optimal NDF content of alfalfa for lactating dairy cows is 40%. We would expect alfalfa NDF to increase by about 5 or 6 NDF units in the next 7 to 10 days. The bottom line is that alfalfa development is well ahead of last year, so be prepared to make an earlier harvest this year to achieve quality forage. Hopefully the rains will slow down soon so we can get planting and harvesting done in a timely manner!

     

  2. Supplementation Of The Lactating Cow In A Grazing System

    Thomas E. Noyes 
    Extension Dairy Agent, Wayne Co.

    Spring is upon us and it's great to see green grass, although winter was very kind to Ohio this year. Spring management and supplementation of the lactating cow is the most challenging time during the grazing season. At this time forage growth is the most rapid and quality changes quickly make management more intense during the spring flush.

    Ideally we would like to keep the grazing height of the forage under 12 inches if you're grazing the tall species (orchard grass and red clover) and under 10 inches if you're predominantly bluegrass and white clover. If you're able to manage your pastures in this manner you will be grazing forage that can be from 24-30 percent crude protein with relatively low fiber with NDF values in the 35 percent range.

    The goal of a supplementation program is to feed the cow to capture as much of the protein as possible and to perhaps provide some fiber to slow down the rate of passage. This can be accomplished by continuing to feed a TMR while you begin to turnout on grass, gradually reducing the amount fed over a 7 to 10 day period. Over that period of time your length of grazing has increased from several hours to now all day grazing. If a TMR is not being used follow a similar program of gradually reducing hay and silage feeding as you increase the length of grazing.

    Many beginning graziers ask about the continued feeding of a forage throughout the grazing season and on many farms this is practiced. I think there can be continued use of the TMR mixer to feed what I call a PMR (partial mixed ration) while grazing. For the high producing cow this is an ideal way of getting adequate grain intake without "slug" feeding. It slows down the rate of passage capturing more of the degradable protein.

    In a grazing system the nutrient most lacking for high production is energy. Therefore, grain feeding should be at a rate consistent with the production goals of the herd but limited to a maximum of 18-22 pounds per day. The content of the grain mix should be primarily a combination of finely ground and coarsely ground corn and perhaps a fibrous carbohydrate like soy hulls along with salt and minerals. By varying the grind of corn and using a fibrous CHO source you vary the rate of fermentation in the rumen thus capturing more of the degradable protein. By incorporating this grain mix with corn silage you've further improved the efficiency of the fermentation process while the cow is grazing.

    In the earlier years of adopting management intensive grazing it was thought that due to the high rate of protein degradability of forage being grazed that a rumen undegradable protein source would be needed. However, feeding trials as Purdue University, here at OSU-ATI and recently at Penn State showed there was no increase in milk production by feeding by-pass protein supplements or by increasing the protein percent in the grain mix to 16 percent.

    Recent Milk Urea Nitrogen (MUN) studies in New York and in Pennsylvania showed as much variation in MUN levels of grazing herds as with confinement herds and there appears to be no advantage to feeding expensive RUP sources. Excess protein actually utilizes energy for removal therefore avoid overfeeding protein.

     
  3. Common Questions Regarding Coliform Mastitis Vaccines

    Dr. Joe Hogan

    Coliform mastitis vaccines have been commercially available throughout the US for several years. These vaccines are based on the immunization of cows with Gram-negative bacteria that have common core-antigens naturally exposed whereby the cows can mount immune responses that will cross-react with a large number of bacterial strains. Most of these vaccines use either Escherichia coli J5 or Salmonella typhimurium Re17 as the antigens. While these vaccines are generally considered safe and effective, a large number of questions have arisen concerning the proper administration and expected results from using these vaccines.

    Q: What improvements will I see in the herd? 
    A: The most common change seen in herds using these vaccines are fewer clinical cases at calving and during the first month of lactation. The proper use of Gram-negative core antigen vaccines reduces the incidence, severity, and duration of clinical signs due to intramammary infections caused by coliform bacteria. These vaccines will not prevent intramammary infections, but enhance the ability of cows to fight the infections once bacteria enter the gland.

    Q: Will I have to vaccinate each dry period or will one series of injections last the life of a cow? 
    A: Unfortunately, cows have little immunological memory toward these vaccines. The protective antibodies in blood return to pre-vaccination concentrations within a couple of months after the last immunization. Cows should be vaccinated during each dry period to maximize protection at calving and during early lactation.

    Q: Will the Gram-negative core antigen vaccines reduce all types of mastitis? 
    A: Most labels of Gram-negative core antigen vaccines specify efficacy against only Escherichia coli. Data from field trials suggest that these vaccines also reduce clinical cases of mastitis by Klebsiella spp., Pseudomonas spp., Serratia spp., and Proteus spp. These vaccines have no effect on mastitis cause by staphylococci, streptococci, or other Gram-positive bacteria.

    Q: Should I use a product that requires two injections or a product with three injections? 
    A: Some products instruct the use of two immunizations during the dry period while others direct the use of two injections during the dry period and a third at calving. The three injection protocol does elevate antibodies in blood at 30 days after calving compared to the two injection regime. Whether the increased antibody titers relate to a decrease in clinical cases during early lactation is currently unknown.

    The timing of the first two injections is constant among products and crucial to the success of the Gram-negative core vaccines. The first injections should be given at the time of drying off with a booster injection given 28 to 30 days later. This will maximize protection during the weeks around calving in cows averaging a 60-day dry period. A vaccination regime that does not protect cows is to vaccinate only at drying off and at calving. The lapse of time between injections is too great for animals to adequately respond to the vaccine.

    Q: Can I treat clinical mastitis with the vaccine? 
    A: Treating clinical cases of mastitis with Gram-negative core antigen vaccines is not recommended. The average duration of an E. coli intramammary infection is less than two weeks. The blood and milk antibody responses to vaccination is maximum 28 days after immunization. Therefore, the infection has almost certainly been eliminated by the cow?s own defenses before the vaccine has an opportunity to affect the disease. These bacterins act as preventative vaccines, not therapeutic drugs.

    Q: Will vaccination cause my cows to abort? 
    A: Controlled trials have shown no adverse effects of these vaccines on pregnancy, feed intake, or milk production. The concern voiced by some experts was that the endotoxin in these vaccines might cause elevated temperatures in cows. Administering the vaccines according to label direction should not affect animal health during pregnancy.

    Q: When starting my herd on a Gram-negative core antigen vaccine, should I immunize the whole herd at once or only as cows enter the dry period? 
    A: Vaccinating cows during lactation is not recommended. The time of greatest susceptibility to coliform mastitis is during the weeks surrounding calving. Label directions for use of the vaccines are intended to maximize protection during this time of greatest risk. As lactation progresses, risk of coliform mastitis greatly diminishes. The use of these vaccines in lactating cows will probably have little beneficial effects and not be cost effective.

    Q: Will the use of coliform mastitis vaccines in first calf heifers be beneficial? 
    A: A trial recently completed in Ohio showed that the advantages seen in vaccinated cows also were realized in first lactation animals that received a primary injection 60 days prior to calving, a booster 30 days later, and a third injection within 24 hours after calving.