Drs. Hardesty and Nusbaum attend AABP in Omaha.  Dr Hardesty took a preconference seminar “The Bovine Estrus Cycle” and attended the Sexing Technologies presentation on the FarmFit monitoring system.  Dr. Nusbaum attended a clinical forum titled “Maximizing the good, dealing with the bad and avoiding the ugly of the immune response.  Dr. Hardesty chaired the Veterinary Practice Management sessions, lead that committee meeting, and was able to get through all of the exhibits.  There were sessions on Clinical Skills, Research Summaries, Dairy and Beef Sessions. We even picked up some thoughts in the students sessions.

Dairy Producers Banquet is Thursday, December 11 starting at 9:30am.   Speakers are Dr. Kirby Krogstat, our new OSU extension educator, presenting “Monitoring Nutrition, Old Classics and New Technology” and “Controlling Mastitis at the Feed Bunk”.  I’ve heard him speak 4 times and every time was very well presented.  Dr. Brittney Davidson is a recent Ph. D graduate from the University of Wisconsin presenting; Consequences of Heat Stress in Dry Pregnant Cows, Growing Heifers, and Post Weaning Dairy Calves.  We’ve known about this science for 5 years, now it is time to get it done and capitalize on the opportunities.  There are so many returns to heat abatement that we need to do this well.

Myco bovis in Calves We have mistakenly thought of Mycoplama bovis as a disease of shipped in calves or randomly in our dairies.  We occasionally have positive diagnostics in respiratory necropsy cases positive.  Dr. Maunsell’s talk is enlightening.  Incidence in calves is 21% on large herds and for some reason, 77% in Tennessee where there are no large herds.  Chronic disease is common, leading to culls, but not so commonly to death.  For every 10% increase in incidence there is a 23% increase in culling before calving. 
 

Myco bovis survives intracellularly in hosts without a cell wall so it is difficult for antibiotics to kill it.  It has a high mutation rate and significant variation, making vaccination challenging.  It decreases immune function.  Increasing myco results in increasing Mannhaemia, three weeks later. It is a primary colonizer of the tonsils, upper airways, and mammary glands.  Once colonized, it can persist and be shed.  It is highly transmissible in confinement and some dairies have a 40 to 100% prevalence.  Some shed intermittently for months to years.  Heifers can infect cows, not just cows infecting calves.

Risk factors include nasal secretions, unpasteurized waste milk (or non-functioning pasteurizers), dirty hutches in calf pens, bucket nipples, flies, weaned calf waterers, and group housing.  Only 2% of colostrum (unpasteurized) are mycoplasma bovis positive.  That fits with what we see in our lab, but we see lots of other organisms in unpasteurized colostrum with huge variation farm to farm.  Are you really double scrubbing teats for first milking colostrum harvest and feeding it or getting it cold in minutes not hours?

Poor air quality contributes as well.  We can reduce that in naturally ventilated barns with positive pressure tubes, tunnel or cross vent barns possibly with kicker or stir fans.  We need to bring in fresh air from the outside or we are simply re-circulating contaminated air.  Necropsy samples are best but this organism can be diagnosed by vigorous nasal swabs.  We can culture your waste milk and you may consider not feeding it.  After we find myco bovis in milk we design a program to control it. Eradication may not happen. For calves, all in, all out works better than continuous flow and nutrition plays a significant role.  We have improved farms with our vaccination and antibiotic metaphylaxis programs.
 

Prolonged Labor Duration There are things we think we can’t affect, but maybe we can.  Dr. McArt documented labor duration.  Unassisted calvings ranged from 20 to 240 minutes with an average of 57 minutes.  Parity 3 and 4 had longer labor duration. Longer labor increased haptoglobins and was associated with dyscalcemia, and negative events.  Maternity management matters.  Having maternity pens in low traffic areas and the use of blinds is helpful in reducing labor duration.
 

Calcium Supplementation  It is now well documented that dyscalcemia leads to poor health.  Cows with high inflammation can benefit from calcium supplementation.  When supplemented they increase milk production, increase conception rate and decrease culling. The challenge is with knowing who the high inflammation cows are.  There will be a time that we have a simple cowside test other than a thermometer.  Until then, supplement all second and greater lactation cows on days 2 and 3 in milk.  Also supplement cows on days 2 and 3 that had twins, milk fever, were lame or thin (<2.8). 

Repro Revelations  A double dose (4 cc) of Cloprostenol (Estroplan or Estrumate) can be used on day 7 of OvSynch instead of two doses of PGf2a (Lutalyse) on each of day 7 and 8.

High producing dairy cows cycle every 23 days so they have older and larger follicles.  Adult cows have low progesterone because of hepatic metabolism.  80% of adult cows have two follicular waves and 20% have three waves like heifers.  Double Ovsynch makes cows breed like heifers, including increased conception rates.  These increased conception rates are the result of setting cows up to have appropriate progesterone levels by the time of follicle selection.  Low progesterone at differentiation increases twinning.  Twins have not increased since 2009.  Unilateral twins on the same side have 3X pregnancy loss as non-twins.  Bilateral are about the same loss as non-twins.

20-30% of cows are an-ovular at 60 to 70 days in milk.  Prostaglandin does very little for an-ovular cows.  When given GnRH, 90% will ovulate.  The second ovsynch in double ovsynch has a high ovulation rate. Some choose to cherry pick those showing heats.  For first lactation, if cherry picked, they have 40% conception, while if they go through the sequence conception it’s 60%. If you are doing Presynch Ovsynch 14-14, you should cherry pick because the follicle is older.  It is better to do a 14-10 or 11 but that puts shots on a different day.  Having an estrus before double ovsynch, increases fertility.  One heat before and one during double ovsynch creates 68% conception rates.  This is because those follicles are almost 4 days younger.  There is often discussion of double ovsynch being too many shots.  It’s 7.  Pre-sych Ovsych is guess what? 7 shots.  Double Ovsych yields a 6% higher conception rate. In total, it is less shots and a step toward having a herd with a high fertility cycle.

The high fertility cycle is based on the fact that fat cows lose weight after calving and cows that lose weight from calving to 21DIM have a 25% CR while their herd mates that maintain weight have a 62% CR.  Thus we want to avoid calving over-conditioned cows by getting them bred.  The best way to get them bred is double ovsynch with a VWP of 60 to 90 DIM followed by re-breeds based on activity monitors and resynching at day 25+ since bred with a decision on opens rather to “Lut” or “G” to rebreed.

There is discussion about breeding sexed semen later, which isn’t needed for double ovsynch, but for walk and chalk it can be a challenge that you may breed too early.  Breeding two times a day based on monitors can pick up 4 to 5 % CR.