As this year’s first cutting hay-making season was going great, I expected that warmer-than-normal conditions might harm hay quality. I knew that Northeast growing degree days were piling up unusually fast.
To wrap my mind around ongoing crop performance data, I contacted Mike Reuter, an analytic services technical manager at Dairy One Lab in Ithaca, NY. I asked him to compare this year’s first cutting performance for mixed mostly grass hay crops to last year’s. On Sept. 6 he emailed me back: “We have not performed any comparisons or made any data interpretations because this information is hot off the press, and I figured you could analyze and make some initial comparison over the weekend. The three-month range that the data were mined for each year was May 1 to July 31. Data from 14 states were summarized – New England, Delaware, Maryland, Ohio, Pennsylvania, New Jersey, New York Virginia and West Virginia.”
Because I felt that the MMG haylage and hay (MMGH – mostly mixed grass hay) crop was representative of other perennial forage classes, I decided to home in on that one category.
First, for 2023, we observed that with 606 (Dairy One) MMGH samples, crude protein (CP) averaged 14.8%, neutral detergent fiber (NDF) averaged 54.1% and net energy lactation (NEL-Mcal/#) averaged 0.64. For 2024, we see that with 982 samples, CP averaged 13.8%, NDF averaged 59.7% and NEL-Mcal/# averaged 0.58.
Let me simplify these figures: NDF and NEL-Mcal/# are inversely related. This means that when one term goes up, the other goes down, and vice versa. Now let’s compare the NEL-Mcal/# for the MMGH forage category for both 2023 and 2024. NEL-Mcal/# for MMGH for 2024 was 0.58. This compares to 2023’s value of 0.64. Divide 0.64 by 0.58 and we see that 2023’s MMGHs support 10.3% more milk than 2024’s MMGHs. It’s evident that 2023’s wildfire smoke blanket proved beneficial to perennial forages, as last year’s lack of effective solar radiation markedly slowed accumulation of Langleys (the solar radiation unit involved here).
Perennial forages took longer to mature, so quality persisted longer, as measured by NEL-Mcal/#, despite later cutting dates. Anecdotal observations from farmers reveal disappointment with 2024’s lab analyses for early hay crops – basically supporting what the Dairy One lab told us regarding that critical early timeframe of our growing season.
Sometimes, when hay yields are down, meadows may be harvested in one year that were left standing the year before. Such roughages often earn the terms “heifer hay” and “dry cow hay” (or “better than snowballs”). I monitor the organic hay situation pretty closely. There’s lots of hay that’s certified organic, but it’s organic by default. The grower didn’t feed the soil any disapproved inputs – actually, that soil didn’t get fed anything at all. Animals fed that kind of hay are usually voracious mineral eaters.
The lack of high-quality roughages in the Northeast has encouraged local hay-deficient farmers to purchase forages grown with deep-well irrigation in the West – areas with low rainfall. These hay sellers consistently test their feeds, so that buyers as well as sellers know what they are getting. Once that hay arrives at the end of its 1,500- to 2,000-mile journey, new owners can do their own analysis, comparing those results with test results that sellers sent in advance of the shipment. From what I’ve seen, very few local hay growers forage test what they’re trying to sell.
So, how do we best utilize less-than-perfect hay crops? Winter provides an easy answer. A major benefit of cold weather is that extra fibrous feeds tend to be more palatable to (or at least more appreciated by) otherwise shivering ruminants. During extreme cold, cattle owners often complain to me that their animals are guzzling down forages at higher rates than the farmers had planned on. I tell them that during really cold weather these bovines – in addition to producing milk (and/or meat) – are mobile furnaces. Cold weather is the best time to feed more fibrous (hence lower energy) forage to ruminants. If they generate body warmth from digesting such fiber, this will lower the extent to which they tap into energy better used for milk production.
Renowned Cornell Animal Science Professor Frank Morrison (1887-1958) discussed the concept of heat increment. He said we can easily envision the energy required by jaws to chew food. But the workings of digestive juices are less visible, as are the increased work of the heart and lungs during rumination. According to Morrison, there are losses of energy through the heat produced by bacteria acting on carbohydrates. The energy expended in all these processes takes the form of heat, which helps warm the body.
Morrison also wrote that speeding up body processes takes place, something which always follows ingesting and digesting food. At the peak of this digestive activity, more heat is produced than at other times, a phenomenon occurring in all animals, particularly ruminants. He said when we are chilly and eat something, we soon feel warmer. Eating too much in hot weather makes us suffer even more from the heat. The rumination process is more intense with high fiber diets – lots more cud chewing, thus increasing an animal’s heat increment (not a good thing in hot weather).
University of Wisconsin dairy researchers have shown that cattle voluntarily consume more feed to meet added energy requirements needed to stay warm when temperatures are below the lower critical temperature intake. Critical temperature with a dry winter coat is 32º; it’s 18º with a dry heavy winter coat.
Intake during extreme cold and blizzards varies greatly, ranging from 2% to 25% voluntary increase. Barometric pressure changes and lack of shelter from the wind where the feed is located influences intake also. Windchill is a factor. A 10 mph wind at 20º has the same effect as a windless 9º reading.
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