Achieving peak milk in the lactation curve has been a topic of discussion for a long time in dairy nutrition, and a benchmark used by dairymen as an indicator of early lactation and transition cow nutrition. Most cows achieve peak milk 45 to 90 days in milk (DIM) and slowly lose production over time until dry-off. It is commonly cited that each pound of additional peak milk forecasts 200 to 250 pounds of milk for the entire lactation. This rule has great significance on the revenue capability of the dairy.
Peak milk as a transition cow monitor
Peak milk, also known as summit milk, has long been associated with the success (or lack thereof) of transition cow management. The transition phase, beginning three to four weeks pre-calving through about 40 days DIM, represents the time of greatest risk to the dairy cow. Metabolic disorders, including retained placentas, milk fevers, displaced abomasums (DAs), metritis (uterine infections) and mastitis are events that limit the cow in her ability to achieve higher peaks. These health events have both major nutritional influences, as well as environmental and social causes, and most often are intertwined. Much nutritional effort has been focused on the pre- and post-calving nutrition phases. Over the years, these improved feeding practices have been responsible for much of the increase in milk production on dairies.
Sound, fundamental transition nutrition, coupled with an excellent stress-reducing housing opportunity for these cows, is imperative. One without the other still cripples the cow’s ability to overcome the stress of calving and post-parturient recovery and can result in poor performance. Your first priority is to give pre-fresh cows enough dry, clean, well-managed bunk space, 30 to 36 inches per head, along with ample resting space. Generally, dairies that fail to give this opportunity to their transition cows will constantly struggle, especially during heavy freshening periods of the year.
Transition nutrition and peaks
The nutrition side of transition is much more complicated, with interactions between minerals and energy status opening the door to metabolic challenges. This, combined with the effects of weather and housing, provide the most opportunity for things to go wrong of any time in the calendar of the cow. Feeding a low or negative DCAD (dietary cation-anion difference) ration by feeding low potassium (K) and sodium (Na) forages pre-fresh is the common focus of mineral nutrition in the dry cow nutrition. This is in an effort to allow the cow to partition rapid use of calcium, phosphorus and magnesium immediately at the time of calving, when there is great demand for these macrominerals. Sometimes the use of anionic salts or commercially available anionic contributors is necessary to curb the metabolic issues associated with these minerals, namely retained placentas, milk fevers or hypocalcemia.
Vitamin and trace mineral nutrition has long been looked to as a transition management aid. The antioxidant vitamin E has been the focal point of this period and continues to show great merit. And you can’t discuss vitamin E without including selenium, as the two are required together. Shortages in these two nutrients have been shown to cause retained placentas and immune system compromise, expressed as fresh cow mastitis or elevated somatic cell count (SCC). The advent of organic selenium has been of great significance in recent years, allowing for safer and more bioavailable sources of this trace element – especially beneficial if you’re in a selenium-deficient part of the country. Other antioxidants, some of which appear to have a “sparing-effect” on vitamin E, may allow for even more efficient use of the these nutrients.
When it comes to energy metabolism, the B-vitamins niacin and choline continue to be heavily researched because of their helpful effects on metabolizing fat in the liver. This organ is like the Grand Central Station of the dairy cow from a metabolic perspective. These B-vitamins have long been thought to be produced in sufficient quantities by the microbes in a healthy rumen. However, research and field experience have shown that providing these B-vitamins, especially in a rumen-protected form, may help reduce ketosis and help the cow metabolize fat more efficiently. This can allow her to achieve better performance in early lactation, leading to higher peak milk. These vitamins appear to be especially beneficial to cows that calve in excess body condition, as these cows tend to have lower dry matter intakes (DMI) at calving. Direct-fed microbials fed during the transition period, aiding in rumen health, may also help stimulate natural production of B-vitamins as well as improve intake and digestion.
The advent of fresh cow drenches or drinkable cocktails that include beneficial yeast, magnesium, calcium, phosphorus, potassium, energy precursors, electrolytes and vitamins have become a popular way to address these potential deficits at the time of calving. While many dairies use these products to treat sick or sluggish cows, research points to the fact that healthy appearing cows may have the most to gain from these nutrients at the time of calving. Repeated research indicates 4 to 6 pounds higher peak milk in healthy cows supplemented with at least one dose of these drenches at the time of calving, as well as a lower incidence of post-calving metabolic events. This can yield up to 800 to 1,500 pounds more milk per lactation from this single supplementation from improved nutrient and health status of the cow at calving.
Sound transition housing, core nutrition and attention to management details provides perhaps the greatest opportunity to influence peak milk and provides opportunity to enhance revenue throughout the entire lactation through reduced metabolic health risk, higher peak milk and overall lactation yield.
Peak milk as a lactation benchmark
The idea that higher peaks mean more total lactation milk is a valid one for most dairies. Monitoring peak milk allows dairymen and their nutrition advisers the opportunity to investigate a number of factors going on in the lactation population.
The use of “peak ratios” – that is, comparing first-lactation peaks against later-lactation peaks – can be useful in determining if there are heifer-rearing problems and as a genetic progress monitor. They can also help determine if there are potential effects of previous lactation nutrition such as acidosis or metabolic problems that might limit peak milk production in one of those age groups of cows. It is generally accepted that a peak ratio of 75 to 80 percent (ratio of first-lactation peak to adult peak) is considered normal. Numbers outside this range can provide the basis for a good investigation.
Simply tracking peak milk on your dairy is useful for monitoring month-to-month change on your dairy. Tracking both the peak milk amount and the average days-to-peak-milk is important in assessing lactation performance as related to nutrition and management. The use of rBST can affect days to peak milk but really has more effect on persistency to the lactation curve. Secondary peaks sometimes occur, and may provide some insight as to rBST strategy, pen moves, group feeding strategies or other management considerations.
High peaks without excellent persistency is not a desired combination. The whole goal of achieving higher peaks is the concept that more mid-to-late-lactation milk is achieved. Pay attention if cows peak early and then fall off rapidly, or simply do not really peak at all. Much care should be given to early lactation nutrition and environmental management to determine why cows fall short. Failure to do so impairs the dairy’s long-term profitability. Following peak milk, the amount of persistency in the lactation curve can be considered the “gravy” milk, and usually represents the milk produced at the lowest cost with the greatest profit opportunity.
Climbing to your dairy’s peak
Using peak milk data is very useful for dairies to evaluate the success of their transition and lactation management. It can give clues as to where to focus attention for transition nutrition changes, especially in association with certain metabolic disorders. It can also provide opportunities in revenue enhancement through improved transition nutritional practices, which can lead to higher peaks. Higher peaks should lead to improved persistency to fully capitalize on total lactation milk production, and if not, provide the basis for improving that part of the dairy. Peak milk has been compared to climbing a mountain: The higher you can climb, the longer the slope down, which is analogous to persistency. Here’s to your dairy’s ability to climb to higher peaks. PD
Daniel Kohls is a nutritionist at the Form-A-Feed and TechMix companies, headquartered in Stewart, Minnesota.
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