PLAIN CITY, OH
Considering the vast array of factors that can affect reproduction success, it's no wonder many dairy farms experience difficulty in their reproduction programs.
"Dairy reproduction is like many different pieces in a puzzle," said Dr. Ray Nebel, Select Sires, during a March 17 webinar sponsored by DairyXnet and the National Association of County Ag Agents.
Dairy producers must find and fix the problems that could be affecting the success of their farm's reproduction program. The contributing factors include labor, nutrition, environment and the cow herself.
Benchmarks can help by providing standards by which a farm's performance can be compared, with key performance indicators a dairy can use to gauge performance and ascertain whether future performance will be a success or failure.
For cows, it's important to watch the weekly herd count of new pregnant animals. It should be between 8-10 percent of the number of milking cows and is dependent on the replacement rate.
Nebel considers palpitation pregnancy rate as the best method to measure heat detection rate. This KPI number should be 60 percent or greater for cows and 80 percent or greater for heifers.
Another KPI is the number of cows leaving the herd within the first 60 days in milk. The number should be 4 to 5 percent at 30 days in milk and 6 to 8 percent by 60 days in milk. "This measures involuntary culling and death and is an excellent indicator of the success or failure of the transition program," Nebel said.
Check the butterfat percentage for the first 30 days in milk. A number greater than 5 percent in Holsteins correlates with cows metabolizing body fat and is an additional indication of the transition program.
Track week four milk weights. By reviewing the trend of weekly milk weight averages, a four-week comparison can be made between different divisions of time. This is another measure to evaluate the transition program, Nebel noted.
Nebel encouraged dairy producers to make use of the free "DairyMetrics" service, available at drms.org, that provides benchmarks driven by herd size, region and level of production.
A farm's pregnancy rate is driven by the conception rate plus the submission rate plus the voluntary waiting period, which should be verified.
Nebel advised dairy producers to look at the pregnancy rate by date and by days in milk. Pregnancy rate report options can be found at PCDART and DAIRYCOMP, he noted.
Five areas have the biggest impact on conception rate: the cow herself, labor, nutrition, environment and semen.
With the cow, the critical areas are the transition program, body condition scores, locomotion, cyclicity, disease and early embryonic loss.
Looking back, Nebel said he has never been on a farm that had a poor transition program and good reproduction.
Body condition scores for fresh cows should be between 3.25 and 3.75. For comfort, keep stocking density at 80 percent and have heat abatement systems in place.
Levels of postpartum diseases should be below 10 percent for metritis and below 5 percent for retained placenta, ketosis and displaced abomasums.
Both pre-fresh and fresh cow pens should have 30 inches of bunk space per animal, and pen moves should be minimized within 10 days before calving. Pay attention to stall size, opt for sand bedding and make sure cows needing medical attention are identified.
The areas pertaining to labor are artificial insemination techniques for semen handling and placement; synchronization compliance; heat detection; motivation; and time budgets.
Correct AI technique is straightforward. Semen must be thawed to 95 F for minimum of 45 seconds. Equipment cleanliness is vital, as is semen handling after thawing.
"You need to maintain that 95 F, which has been tough this winter, almost impossible," Nebel said.
The semen should be placed one-quarter inch past the cervix into the uterine body. "These are fairly simple rules, but they are violated daily," he said.
Almost 50 percent of cows in the United States are bred today with timed AI programs, underlining the importance of synchronization compliance. Make sure cows are getting the right injections at the right time, Nebel advised. Review the protocol and timing of hormone injections, as well as hormone storage and equipment.
Use 19 gauge, 1.5 inch needles, and check when and if the needle is changed. Too often, needles are replaced only when it becomes difficult to shove them in, Nebel said. "After two or three injections, the needle probably needs changing. Ideally, every cow gets a different needle."
Facilities and cow comfort have come a long way in the past 25 years, but this area can still be the sources of issues. Sometimes, problems can sometimes be identified by checking the conception rate by month. A drop in July, August or September should spark a discussion on a heat abatement program geared at reducing heat stress, Nebel suggested.
Time budgets are another important component of reproductive success. Cows should be eating for 3-5 hours a day and consuming 9-14 meals. They should be lying down or resting for 12-14 hours, drinking for 30 minutes and standing or walking in the alley for 2-3 hours. "As herds get larger, this becomes more critical," Nebel said.
Stocking density is determined by headlocks, bunk space and stalls. While the ideal for pre- and post-fresh cows is 80 percent, most dairies are stocked between 115 and 120 percent, Nebel said. The result is a drop in reproduction and decreased milk production. Six-row barns are particularly bad, he added.
The size of the stalls and lunge space should be matched to the size of the animals, with enough bedding provided, preferably sand, to keep the cows comfy. There should be heat abatement in the stalls and in the holding pens, where cows are crowded together and heat stress intensifies.
Cows also need good foot care, including hoof trims and foot baths. Review the cases of mastitis and watch the percentage of time cows spend cud chewing.
The section of the reproduction puzzle that deals with semen involves whether sex semen or conventional is used, as well as the sire's conception rate.
Today, most dairymen are back to using sex semen, a reflection of the $2,000 average value of heifers across the country. Raising and selling heifers is profitable now, compared to the last few years, Nebel noted.
However, breeding with sexed semen still means lower conception rates than with conventional semen, coming in around 78-80 percent of conventional semen rates. "There have been improvements, but it is still not equal," Nebel said.
Heat detection is critical, whether through visual observation or walk-and-chalk systems. Make sure workers are motivated, and there is adequate time budgeted for the job at hand.
Keep an eye on rumen health by monitoring the incidence of acidosis and ketosis, as well as water intake; watch the ration in terms of particle length, mixing and delivery; and evaluate manure. "There is a sound biological basis for why manure looks the way that it does," Nebel pointed out.
Acidosis is identified by low milk fat tests (below 3), sore hooves, laminitis and cycling feed intakes, as well as diarrhea, liver abscesses, limited cud chewing and low rumen pH (below 5.8) in 30-50 percent of animals tested.
Ketosis usually occurs within a few days to a few weeks after calving. It is characterized by low blood glucose, lack of appetite, weight loss, depressed milk production and excess ketone bodies in blood and urine.
Be aware that any factor resulting in a reduction of dry matter intake increases the risk of ketosis, Nebel noted.
Mycotoxins are another big piece of the reproduction puzzle, with at least six kinds known to affect dairy herd fertility. "Controlling mycotoxins presence is, therefore, extremely important," Nebel said. "They may be a relevant cause of infertility in lactating dairy cows."