We need to use the best science and management practices in feeding our cows. Even when milk prices are low, it is still well above the cost of feed. Feed costs are around 11 to 12 cents per pound of dry matter (DM), and for each pound of DM consumed by your cows, you will get 1.5 to 2 pounds of milk. If you cut ration costs by 20 cents per cow per day and lose 2 or more pounds of milk, it is a losing proposition. A better idea is to fine-tune your feeding program and ration costs in the following areas:
Protein
When excess protein is fed (typically over 18% DM of the ration), the protein is deaminated by rumen microbes into ammonia. When dietary carbohydrates are inadequate to capture the protein, ammonia is absorbed from the rumen and then converted to urea in the liver. The energy costs for detoxifying ammonia into urea represents energy loss and may impair milk production and reproductive efficiency. In addition, excess levels of urea can impair liver function, reproductive activity and the immune system. Overall, feeding excess protein will increase feed costs and provide no beneficial effect on milk production or composition.
Diets need to be evaluated to ensure they contain adequate and balanced amounts of amino acids without excess levels of protein. To further optimize the efficiency of protein utilization, supplements that are high in readily fermentable carbohydrates, such as molasses-based liquid supplements, can be fed to enable rumen microbes to capture and synthesize more microbial protein. Cows should also be frequently monitored for milk urea nitrogen to ensure the protein and carbohydrate fractions are balanced.
Fat
Supplemental fats are commonly added to the diet to increase dietary energy density and to support milk production. As cows milk more, they need more energy, and there is a limit on how much starch can be fed. As a rule of thumb, total fat should not exceed 5% to 6% of the entire diet. The amount of fat that can actually be included in diets depends on the fat source, dry matter intake (DMI) and fiber level of the diet. Many problems can occur when feeding high levels of fat, such as reduced DMI, decreased feed digestibility and milk fat depression. Interactions with other dietary components are also important in determining the response to various fat supplements. From the cost standpoint, commercial fatty acid supplements are among the most expensive ingredients in the ration and should be used cautiously or can be partially replaced by other more economical energy sources, especially in times of low milk prices.
Just like all protein or sugar sources are not the same, not all fat supplements are created equal. It is important to know the profile of the fatty acids and their degree of unsaturation. These factors directly affect DMI, rumen metabolism, fat digestibility and milk component production. For example, recent research suggested fat supplements that are high in palmitic acid (C16:0) tend to increase milk fat synthesis. If fatty acids are unsaturated (such as vegetable and plant oils), they must be biohydrogenated by rumen bacteria so not to be toxic to the bacteria. Too much dietary unsaturated fat can easily overwhelm this process, causing incomplete ruminal biohydrogenation. When coupled with a high level of dietary starch and inadequate effective fiber, these unsaturated fats can interfere with rumen fermentation, resulting in milk fat depression.
In addition, there are significant differences in the rate of fatty acid ruminal availability; for example, distillers grains, ground soybeans or oil supplements have a much faster release of fatty acids in the rumen than whole cottonseed and whole roasted soybeans. Generally speaking, supplements that are high in saturated fat do not increase the risk of milk fat depression. Overall, the addition of fat to the diet may improve energy balance, milk production and reproduction. However, feeding fat must be carefully monitored for negative effects on feed intake, milk production and milk components.
Sugar
Numerous studies have shown that dietary sugar supplementation is a feasible way to help increase milk component yields. A published meta-analysis evaluated a database of 24 published scientific research trials. The study found that dietary sugar supplementation increased milk fat and protein yields, and the optimal response was observed when total dietary sugar was between 6.75% to 7.5% of DMI. Specifically, cows producing more than 74 pounds of milk had an 0.18-pound increase of milk fat, 0.2-pound increase of milk protein and a 4.7-pound increase of 3.5% fat-corrected milk. When corn is cheap, some dairy herds tend to feed too much starch, pushing the rumen close to or over the edge that leads to inefficiencies and health concerns, but not feeding enough dietary sugar or soluble fiber to optimize rumen fermentation, protein utilization and fiber digestion.
Forages
High-quality forages provide effective fiber for the cow to maintain rumen health and also provide high-quality nutrients to support production. Feeding higher forage diets can provide dairy herds with many long-term benefits, including higher levels of milk components, improved cow health, reduced purchased feed and grain costs, and increased profitability. The key is having adequate quantities of consistent and high-quality forage available on the farm and good management.
In today’s tough milk market, dairy producers and nutritionists should reevaluate their rations to make sure they are feeding the most cost-effective diet to optimize income over feed costs. Excess levels of nutrients and additives may be able to be cut back to save costs and improve productive efficiency. 
References omitted but are available upon request. Click here to email an editor.
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Kai Yuan
- Senior Research and Technical Adviser
- Quality Liquid Feeds Inc.
