Feeding the dairy herd
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A successful dairy feeding system is defined as one that delivers the needed nutrients to each cow at the correct time (stage of lactation) to maintain maximum milk production. No one system is correct for all dairy producers. The feeding system selected must consider delivery of forages, grain, protein and minerals, either individually or in various combinations.
Forages are classified as feeds high in fiber and low in digestible nutrients, and include whole plants of corn, small grains (such as oats, barley, or wheat), legumes, and grasses. Forages are the primary source of fiber required by the cow to maintain rumen digestion and function as well as to stimulate rumen microbial growth, rumination, and saliva production. Forages are usually a more economical source of nutrients than grains, protein supplements, or mineral-vitamin premixes.
Forage selection depends largely on agronomic considerations (such as soil types, climate, yields, and nutrient yield per acre). Forage quality must be the primary consideration regardless of forage type. High quality forage will be consumed in larger amounts and is more digestible than mature, lower quality forages. Addition of grain to diets cannot completely compensate for lowered animal performance from low quality forages.
Forages can be of several different types, each varying in chemical composition, moisture content, and physical form. The trend over the years has been to increase the use of ensiled forages due to convenience, ease of mechanization, reduced labor, more uniform quality, increased yield per acre compared with pasture, and lower field losses compared with hay. Increased harvest losses and potential rain damage (due to extra drying time required) are associated with dry baled hay (figure 7). Use of a drying agent at cutting and/or a propionic acid-based preservative to permit baling at a higher moisture level offers a method of reducing drying time. Table 11 lists the comparative advantages of several methods for storing dry hay. Large round bales and 3-ton stacks are not easily moved and are seldom easily fed in stanchion barns.
Haylage minimizes DM losses and weather risks, and has the advantage of being adaptable to mechanization in harvesting, storing, and feeding. The optimum storage system for haylage or other silages will depend on inventory needs and availability, continuous feed features, refill and/or double filling patterns, and the feed system. Tower silos, both conventional and limited oxygen, bunker silos, and large plastic bags have all been successfully used for storage. Table 12 compares costs of these systems.
Pastures can provide significant quantities of high quality forages to dairy cows and heifers if managed intensively. Potential benefits of a pasture-based forage system for dairy herds include:
- increased yield and quality of forage from land that previously was unproductive
- decreased equipment and fuel for harvesting forages
- less manure handling and lower bedding costs
- reduced weather related risks in harvesting forages and
- potential for better animal health because of increased exercise.
Limitations to pasture-based forage systems are:
- maintenance of high yields and quality of forages during the entire growing season
- correct supplementation to maximize productivity and profitability from pasture forages and
- the short length of the grazing season in some areas.
The optimum forage system for a given farm depends on the amount of forage required, storage method, and ease of accessing forages of different qualities. Situations often leading to forage allocation problems include second cutting hay piled on top of first cutting hay; a conventional top-unloading upright silo with first cutting haylage on the bottom, second cutting haylage in the middle, and third cutting haylage on top; or a conventional top-unloading silo with haylage on the bottom and corn silage on top. These situations do not allow for the optimal utilization of forages, as one quality of forage must be fed to all animals until it is depleted. Different animals can utilize different quality forages more efficiently. An optimal forage system allows for the segmenting of forages by quality. The solution may be to have several smaller silos instead of a few large units. This approach would also allow for a gradual shift between forage types rather than abrupt changes.
Dairy producers storing more than 1,000 tons of silage annually, especially corn silage, find that bunker silos are more economical and are more reliable because they are less vulnerable to power failure or breakage of mechanical unloading equipment.
Forages are most often fed free-choice or in a total mixed ration (TMR). When fed free-choice, forage should be available to cattle at all times. Cows without forage or feed for more than 3 hours per day are not full fed. DM intake, and consequently milk production, is reduced when cows are not full fed.
Tie-stall barns. Feeding cows housed in a tie-stall or stanchion barn generally requires more labor than feeding cows housed in a free-stall barn. Grain can be fed by mixing all ingredients (complete grain mix) except forage, or can be fed separately (high moisture corn) from other ingredients (topdress feeding of protein supplement and/or mineral and vitamin supplement). It can also be included in a TMR. Mechanical equipment is available that minimizes labor needed to hand feed grain. This varies from a simple push cart to computerized monorail feeders to fully automated overhead auger systems filling storage containers located at each cow stall.
Free-stall or loose housing herds. Feeding correct amounts of grain in a parlor is difficult due to the limited time cows are actually in the parlor. Also, parlor efficiency is usually compromised when all or a major portion of grain is fed in the parlor. Elimination of parlor grain feeding will reduce dust and defecation in the milking area, improve cow flow, and reduce overfeeding of low producers and underfeeding of high producers.
Several mechanized grain-feeding systems are available to replace or supplement the parlor grain feeding system.
- Free-choice, electronic grain feeders. These units allow cows equipped with an identification unit (either a magnet, key, or chain) access to a feeding station. These systems do not restrict access time or amount of grain consumed per feeder visit. Careful management is required to avoid digestive problems. The major advantages of these systems are a lower initial investment and a simple design.
- Preset or computerized grain feeders. These systems control the maximum amount of grain individual cows receive during a set period of time. Initial costs of these systems vary widely depending on herd size and complexity of the system. Some features associated with computerized feeders include:
a. A printer to list individual and total daily grain intakes. b. Identification of cows not consuming their allocated grain amount. c. Ability to proportion the grain allocation over time. d. Ability to proportion more than one grain mix or bin contents. e. Warning system to signal a feed blockage, component problem, or power interruption. f. Milk data combined with other information to provide more herd management information. g. Capability of providing the entire daily grain allocation for individual cows and/or for the whole herd through computer feeders.
Regardless of which feeder system is selected, successful adoption requires excellent management. Recommended number of cows per feeder is between 20 and 25. Stall length, protection of the unit, and location of the unit relative to cow traffic patterns also can affect success of the unit. Table 13 lists typical rates at which cows consume various types of grain.
Another method of feeding grain in free-stall or loose housing is through a TMR with forages and all other feeds combined. Separation of cows into production groups is recommended for this method to succeed.
A survey of the top 50 DHIA herds in Minnesota in 1991 indicated method of grain feeding had no effect on milk production (Table 14). Success with any method requires that the nutrient content of the grain portion of the ration complement the forage program and provide the nutrients necessary to meet requirements for the desired level of milk production.
The amount of supplemental protein fed is usually controlled by making it part of a grain mix or TMR, or by top dressing. However, lick wheels are one means by which protein supplementation is offered free-choice. Intake of urea-molasses (liquid supplements) from lick wheels usually averages from 1 to 2 pounds per animal daily. If feed is limited, intake can increase to 5 to 10 pounds per day and can result in urea toxicity problems. Lick wheels generally are not recommended for lactating cows with differing protein needs, since cows are unable to balance protein needs. The lick wheels may have value, however, when the protein requirement of all animals in a group is uniform, such as with dry cows and growing heifers. Consider cost of liquid supplements and do not depend on the cows' ability to balance protein needs.
Two basic systems for feeding minerals are:
- Force feeding systems where the minerals are mixed with grain and/or forage, fed in a total mixed ration, or topdressed.
- Free-choice systems where cows have unrestricted access to various mineral mixtures. Cafeteria-style mineral feeders are an example.
Several studies have demonstrated dairy cattle are unable to balance their mineral requirements through free-choice feeding alone. Therefore, a cow's mineral requirement, including salt, should be met through force feeding in the ration, with supplementary calcium-phosphorus minerals and salt offered free-choice. Mineral sources should be evaluated on cost per unit of mineral and quality of mineral source.
Total Mixed Rations
Total mixed rations (TMR), or complete rations, are defined as those with all the forage and grain ingredients blended together, formulated to specific nutrient concentration, and fed free-choice. The main advantages to TMR feeding are:
- Cows consume the desired proportion of forages when two or more forages are offered.
- Cows consume the desired amount of forage relative to the amount of grain offered.
- There is less risk of digestive upsets.
- Feed efficiency improves.
- It allows for greater use of unpalatable feeds, NPN sources, and commodity feeds.
- There is potential to reduce labor required for feeding.
- It allows for greater accuracy in formulating and feeding.
The potential disadvantages include:
- It requires a significant equipment investment in a mixer.
- It creates a need to group cows into two or more groups.
- Rations must be carefully formulated and continually checked.
- Pasture feeding and large amounts of long hay are difficult to incorporate into rations.
Small mixing units and feed carts equipped with weigh cells are available. These work well in smaller herds (40 to 60 cows) or herds in tie-stall or stanchion barns. Equipment cost will vary depending on size, mobility, mechanization, and weighing devices involved. Electronic load cells are most accurate (1/10 to 1/4 of 1 percent) but require a level setting. Weigh bars can be used on uneven slopes (such as mobile mixer-truck) but are less accurate (1 percent). Both types are acceptable when managed properly.
Dividing cows into production strings is a critical factor for the success of TMR feeding. Consider the following guidelines for grouping cows:
- A minimum of two production groups plus a dry group. More groups may be required as herd size increases. A separate group for first-calf heifers is advisable because of their smaller size, lack of competitiveness, and additional growth requirements compared with mature cows.
- Once fresh cows have recovered from calving (usually 3 to 7 days), put them in the high group to challenge them nutritionally for 3 months. Move cows to a lower production group when milk output does not warrant keeping them in a higher production group and/or body condition is restored.
- Drastic drops in milk production should not occur when cows are moved from a higher to a lower production group if rations are properly formulated.
- Several options are available for moving cows.
a. Move small groups of cows, rather than individuals. b. Move cows at feeding time to minimize cow interactions. c. Move cows on a regular schedule. d. Consider reproductive status when moving cows. Try to limit heat detection to one group. e. Increase grain by 5 pounds for several days after cows are shifted if computer feeder is being used.
- Formulate rations to meet nutrient requirements of the top third of the cows in each group.
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