A case report: Is sorting a contributor to low milk fat and reduced profitability on your farm?
I visited a dairy farm in southwest Michigan yesterday to help troubleshoot low milk fat issues. This herd has 200 milking cows, 90 lbs/cow/d milk yield, 3.3% fat, and 2.9% protein. In today’s tough milk market, a good milk fat content is especially important to milk income. By using MilkPay.com, I showed the dairy producer that if his cows can increase milk fat by 0.3%, his milk income can increase by over $50,000 per year, and that’s even based on current extremely low milk prices. Just imagine, for a 1000-cow dairy herd, that 0.3% unit difference would worth over $251,000 per year. I think 3.6% milk fat shouldn’t be difficult to achieve as long as we can tweak his nutrition and management programs effectively.
After studying his ration, there were several risk factors might contribute to low milk fat, including: 1) Fairly high starch content (30%) with large amounts of high moisture corn in the ration, which can lead to rapid starch fermentation in the rumen and drop rumen pH; 2) Excessive amounts of unsaturated fatty acids in the ration (~700 g/h/d), together with low rumen pH, this can produce undesirable fatty acids in the rumen and inhibit milk fat synthesis. 3) Low dietary NDF, and there were variations in manure consistency, indicating that cows sorted the diet.
It is often said that there are four radically different rations for a group of cows: the ration that is formulated by a nutritionist, the ration that is fed, the ration that is eaten by the cows, and the ration which is digested. If sorting is a big issue in this herd, then many of the cows are likely to consume excessive amounts of starch and unsaturated fat. And sorting against long fibers would further exacerbate milk fat depression.
To do a quick and dirty evaluation on sorting, I took a few sets of samples. As shown in Figure 1, the sample next to the cows represents the feed that had been eating for 2 hours, and another sample represents the “fresh” feed that cows hadn’t reached.
Figure 1: Samples were taken to evaluate sorting behavior. The sample next to the cows represents the feed that had been eating for 2 hours, and another sample represents the “fresh” feed that cows hadn’t reached.
After shaking the samples through Penn State Shaker Box (Figure 2), I found that after 2 h of eating, there were much more feeds on the top screen (35 vs. 22%) and much less feeds on the bottom pen (14% vs. 21%), a sign of sorting.
Figure 2: After 2 h of eating, there were much more feeds on the top screen (35 vs. 22%) and much less feed on the bottom pen (14% vs. 21%), a sign of sorting.
Another issue was that there were too much long particles on the top screen compared to the standard guidelines (Table 1), which should be 2 to 8%. Apparently, these effective fibers were sorted out by some of these cows on the farm. I have to admit that the feed was pretty wet, which might affect the accuracy of shaking results. Nevertheless, lack of effective fiber consumption and excessive intake of grain likely contributed to low milk fat of these cows.
Table 1: Standard guidelines of shaker box and the ration separation results of this farm. Note the upper sieve long fibers were sorted out excessively after 2 h of eating.
Similar to this farm, a recent work from Cornell University evaluated the particle size distributions for 74 herds' prefresh cow TMR samples (Figure 3) and they found out that there were way too much long particles compared with the standard recommendations.
Figure 3: Particle size distributions for 74 herds vs. standard recommendations.
It is convincing to me that excessive amounts of sorting is a contributor to low milk fat on this farm. What can we do to reduce sorting? The dairy producer probably needs to reduce the chopping length of forages. Increasing the feed mixing time and improving mixing procedure will help as well. The producer also told me that one of the blades of his mixer wagon was broken, and we have to fix that immediately. In addition, adding molasses-based liquid feed can help reduce sorting. According to a recent published work in Journal of Dairy Science by Dr. Trevor Devries at University of Guelph, adding a molasses-based liquid feed supplement to a TMR reduced sorting, and increased dry matter intake, milk fat yield, and energy-corrected milk yield. Similar results were reported by researchers from The Ohio State University.
Last summer, a group of intern researchers evaluated dairy cow sorting behavior in Wisconsin. The project was led by Paul Dyk from Quality Liquid Feeds, Inc. (QLF). They collected data from 78 farms representing nearly 100,000 cows. One interesting aspect they evaluated was the effect of type of liquid in ration on sorting behavior. As shown in Table 2, cows supplemented with molasses had the greatest reduction in sorting compared with other liquid types.
Table 2: A large on-farm data set shows that molasses is the most effective liquids in reducing sorting. Note the greater the values are (relative to 100%, which means no sorting), the greater the cows are sorting against the particles.
Summary:
In short, here are my few suggestions to improve the low milk fat issue on this farm:
Reduce the amounts of unsaturated fatty acids in the ration.
Reduce highly fermentable starch sources, and use dry corn and QLF sugar liquid feeds to replace some of the high moisture corn.
By using liquid feeds, the producer can include more forages/NDF in the ration and cows should increase forage intake and fiber digestive efficiency.
Push up feeds more to stimulate meal frequency and consistent rumen fermentation.
Chop the very long forages shorter.
Fix the mixer wagon.
Mix the TMR more thoroughly.
Target less long particles on the top sieve of the shaker box; may shift to middle sieve.
Use QLF liquid molasses-based supplements to help reduce sorting.
Pray for a cooler weather and cool the barn!
Hopefully, with the further fine-tune of nutritional and management strategies, this dairy producer will see an increase in milk fat content and milk income soon!
