Dairy producers understand the delicate balance between maximizing milk production, controlling costs and ensuring the long-term sustainability of their operations. Efficiency in milk production per cow is a cornerstone of dairy farm profitability and sustainability. In recent years, advancements in reproductive technologies have offered promising opportunities to enhance the efficiency and profitability of dairy farming. However, effectively leveraging these tools requires a thorough understanding of their potential benefits and challenges.
One of the critical challenges facing dairy producers is the unnecessary culling of multiparous cows (second lactation or greater). This not only results in decreased herd average milk production but also leads to increased replacement costs and diminished operational efficiencies. Remarkably, as many as 50% of cows leave the herd before their third lactation, highlighting the urgency of addressing this issue. A general goal to shoot for is for about 70% or more of the herd to be multiparous cows at any given time. To accomplish this goal, there are several aspects of reproductive management that must be controlled.
It is critical to ensure that multiparous cows receive timed A.I. following a first-service fertility program such as Double Ovsynch, G6G, G7G or Presynch-11/Ovsynch. Recent data from our laboratory indicated that multiparous cows had a 260% greater chance of pregnancy in an initial first A.I. breeding window (69 to 94 days in milk) when managed with Double Ovsynch compared with detection of estrus with automated activity monitoring. Cows in each group had an equal chance for pregnancy loss of around 10%. Cows in both groups had greater chances for pregnancy if they were cycling prior to this breeding window.
Tip 1
Be sure that all multiparous cows receive timed first A.I. before 85 days in milk.
Goal: 50% pregnant at initial pregnancy diagnosis (around 35 days post-A.I.).
Tip 2
If possible, utilize automatic activity monitoring to detect returns to estrus in non-pregnant cows.
Goal: To detect approximately half of the non-pregnant cows. It appears that a significant number of losses occur between “conceptus attachment” at around 20 days post-A.I. and the first pregnancy diagnosis. These cows are less likely to be detected in estrus prior to the first pregnancy exam.
The value of early pregnancy is much greater in multiparous cows compared with first-lactation cows. Pregnancy before 130 days in milk results in fewer chances for excessive body condition at calving, which in turn translates into less body condition loss following calving, fewer postpartum diseases and greater chances for pregnancy in the next lactation. Cows with reduced body condition loss after calving also have lesser chances of pregnancy loss after the first A.I. This is known as the high fertility cycle.
It doesn’t appear that early pregnancy in primiparous cows translates into positive effects in their subsequent lactation. Pregnancy before 85 days in milk results in approximately a quarter of these cows having too low of body condition at second calving, leading to reduced milk production and more health problems following second calving. Consequently, there exists greater flexibility in the reproductive management of first-lactation cows in contrast to multiparous ones. First-lactation cows can benefit from the adoption of in vitro-produced (IVP) embryos or sexed semen without the added concern of extending calving intervals. Yet, due to increased pregnancy loss following IVP embryos and sexed semen, intensive reproductive management of first-lactation cows is still paramount. Studies are needed to test a delay in time for first A.I. in primiparous cows.
Tip 3
Sexed semen or IVP embryos can be used in heifers and first-lactation cows but not multiparous cows. It is risky to use these technologies in multiparous cows due to reduced pregnancy rates and greater pregnancy losses. It would exacerbate unnecessary culling of these valuable cows.
A clear advantage of utilizing sexed semen in first-lactation cows is the option to use beef semen in the lower genomic value primiparous cows and all the multiparous cows. Four advantages are:
- Increased calf prices: Utilizing beef semen on multiparous cows offers the opportunity to capitalize on calf sales.
- Faster genetic progress: Sexed semen in heifers and first-lactation cows offers the opportunity to accelerate genetic progress of the herd.
- Increasing average milk per cow with a greater percentage of multiparous cows: Limiting the number of replacement heifers needed each year reduces the conventional dogma to calve all heifers born from conventional semen on all cows. Planning for a 30% replacement rate puts pressure on management to maintain a greater percentage of high-producing multiparous cows.
- Cost of rearing replacements: Raising replacement heifers represents a significant cost for dairy operations. By utilizing a beef-on-dairy program, producers can optimize the replacement strategy, potentially reducing raising costs while enhancing the quality of replacement heifers.
Tip 4
Primiparous cows receiving sexed semen should be synchronized with a fertility program such as Double Ovsynch or G6G. The reason is to maximize the chances of a pregnancy.
Tip 5
Detect pregnancy early and often. Pregnancy diagnoses with ultrasound or pregnancy-association glycoproteins (PAGs) around 35 days post-A.I. in concert with an Ovsynch (cows with corpus luteum [CL] at open diagnosis) or GnRH – seven days later – Ovsynch (cows without CL) re-synchrony program is critical for ensuring pregnancy in multiparous cows before 130 days in milk. Rechecking two more times prior to 120 days post-A.I. will find most pregnancy losses and will help to gain a greater understanding of potential replacements needed in the future.
Lastly, new data from our laboratory indicates that approximately 65% to 80% of primiparous and 55% to 65% of multiparous cows are pregnant and have conceptus attachment based on daily PAG levels. Yet many of these cows lose these pregnancies within the next two weeks. Gaining a greater understanding of why this happens could lead to greater efficiencies in the future.
Adopting new management strategies plays a vital role in driving innovation and sustainability within the industry. Embracing advancements in reproductive technologies can optimize the productivity and longevity of dairy herds. From reducing unnecessary culling to enhancing milk production, there are numerous opportunities to improve the efficiency and profitability of dairy farming.
