Managing Beef Cattle on Forage
Forage System Development
To start evaluating an existing or potential production system, the producer should consider the goals of the beef operation and the physical limitations of the land base to be used. In many situations, soil type and topography will have a lot to do with the make up of the final forage system. Any system to be used for brood cow production needs to produce medium to high quality grazing nearly year around, while stocker systems are more flexible and may be the system of choice for producers who do not produce forage during a significant time during the year. In general, forage systems should be built around perennials, because annuals are expensive due to high seed and establishment costs.
For most cow-calf systems in the coastal plain, a balance of cool and warm season forages will be needed, and several systems of this type are described in Chapter 16 of Bulletin 305. In the Coastal plain, most systems will utilize either fall or winter calving, and this depends on if high quality grazing is available in the fall. The best mixed system will be a combination of bermudagrass/crabgrass (or other warm season perennials), fescue, and small grain either in rotation with millet, or overseeded on the warm season perennials. Spring calving is usually not successful in the coastal plain, due to the potential for extreme heat stress during the breeding season.
In the Piedmont, fall, winter or spring calving may work on a given farm, and will depend on the relative acreage of warm and cool season forages. In the Mountains, spring calving is likely the best choice of systems due to the high cost of winter feeding of fall calving cows, and the potential for both high feed cost and high calving losses as a result of severe weather conditions with winter calving cows. The mountain system may not require warm season forages (other than native warm season plants that invade pastures in late summer and fall) because cool season forages will grow well through the summer.
Most old pastures in the piedmont and mountains evolve into a mixture of cool and warm season forages, and strategic use of fertilizer application can provide high quality grazing when it is needed. Many producers think it is necessary to reestablish pastures after the main seeded variety starts to decrease in stand share, but in most situations a pasture will evolve into a plant community that can be maintained indefinitely. If reseeding is needed, overseeding perennial grasses and legumes is often a better alternative than complete destruction and reestablishment. In general from 1.5 to 2.5 acres will be needed to support one cow/calf unit.
Stocker cattle need high quality forage to perform. The systems that work best are winter grazing on rye/ryegrass pastures, grazing on stockpiled fescue (with some energy supplement provided), or summer grazing on crabgrass, switchgrass, eastern gamma grass or other high quality warm season forages. Bermudagrass doesn’t have the quality potential to be very good for stockers without grain supplementation. We have consistently had 1.75-2 lb/day summer gains on bermudagrass with 3 lb of grain as compared to 1.25-1.5 lb/day with bermudagrass alone. Most cow-calf producers should consider stockering their own calves (depending on economic conditions each year) and selling them weighing 700-800 lbs at one year of age, which adds diversity and flexibility to the system.
Once the system is laid out in terms of the acreage and production available, we can estimate the carrying capacity of the system and where the potential holes are in the feed supply. This will give you an initial idea of what a target will be for stocking. The fencing and watering system should be installed before stocking if possible as that will facilitate getting things going. When modifying an existing system, the producer will have to work around the day-to-day needs of the cattle and this complicates things. Once the permanent pastures are laid out and established, it is time to take control of the animal groups.
Use of Animal Grouping in Your Management Program
Animal grouping is the key to efficient management of animals on pasture. The various classes of animals have a range of nutritional requirements (Chapter 16, bulletin 305) with baby calves being very high, followed by light calves/stockers, developing replacement heifers and bulls, young cows, and mature cows (and bulls) who have the lowest requirements. In late fall and early winter, most cow-calf operations using winter and spring calving will have a group of weaned calves (at least the replacement heifers), a group of bred replacement heifers, dry cows, and bulls. Fall calving herds will have lactating mature cows, lactating two-year old heifers, developing yearling heifers and bulls.
In the winter and spring calving situation the weaned calves have the highest requirements, and should be in the highest quality forage available. If the quality is inadequate they may need a grain supplement with an ionophore. If not, they should be fed a free choice mineral containing an ionophore unless they are replacement heifers well ahead of schedule in terms of development. The yearling replacement heifers may be used as a follower group for the calves, or may be used as a leader group for the dry cows. Regardless, the dry cows will be used to clean up the lowest quality forage available, with a goal of having them in body condition score of 6 at calving. The replacement heifers should be gaining about 1 lb/day and should be in a body condition score of 6.5 at calving. Some people want heifers to be a little thin at calving to help reduce calving problems, but it really doesn’t help, and the calves tend to be weak at birth and the heifer is slow to breed back.
For the fall calving situation, the developing replacement heifers and lactating two-year olds have the highest requirements. They may be managed in the same group on small operations. These animals should get the highest quality grazing and/or hay available and will usually require an energy supplement such as grain or whole cottonseed. The lactating cows have moderate requirements and should be fed medium quality hay or pasture (stockpiled fescue) or lower quality hay with a supplement. There is not much use for low quality hay on a fall calving cow-calf system.
Evaluating Nutritional Status
There are two major tools that you will use day to day to evaluate when animals are ready to move to fresh grass. One is the fill that is visible in the animals stomach, and the other are their behavioral cues. A well fed animal, where the goal is gain, will appear “full” most of the time. If these animals are allowed to become “gaunt” before moving, their performance will be hurt. In general, neither weaned calves nor replacement heifers should not be allowed to get empty. Dry cows, on the other hand, will probably become a little gaunt before moving is necessary.
The other tool in determining short-term nutritional status is the animal’s behavior. A well fed, contented animal will not get excited when they see you. The animals will begin to understand that you provide them feed when they need it, so when they see you and also are declining in their nutritional plane they will let you know it. Tuning in to what the animals are telling you is important. If they are almost impossible to drive out of a paddock, they probably don’t need to be moved. Fecal consistency is useful in determining quality of the diet. Low quality results in “tall stacks”, medium quality in “cow pies”, and high quality the “grass scours”.
Body condition scoring is the tool you use in the medium to long-term to evaluate the animals’ status and whether you are cutting them too tight, or letting them waste feed. The dry cows need to clean up closer than the other groups, and they will be unhappy by the time you move them to fresh grass, but as long as you maintain their body condition that’s fine. Growing animals should be in body condition score 6 most of the time which indicates that they have adequate nutrition to grow at their genetic capability. Day to day mistakes in the amount of grass offered are inevitable and should be picked up by the short-term cues. If the mistakes are consistent, then body condition will start to suffer. Cows should be in an operating condition of 4-7 throughout the year, and the replacement heifers should never fall below a 5.
The group we haven’t talked about are the bulls. Housing the bulls is a problem, and it seems that the best option is to maintain them in a pasture of their own that supplies about 2 acres/bull and then be prepared to feed them hay as necessary. They may need some grain supplementation starting 60 days before the breeding season so that they have a body condition score of 6.0 when put with the cows.
There are some other management considerations you should be thinking about. They include the use of a good mineral supplement, perhaps the use of alternative supplements like cottonseed and soybean hulls, and the use of creep grazing and other advanced grazing techniques. These topics will be handled in detail in several of the handouts provided to you.
A high quality mineral program is very important in these more intensive forage systems. Potentially, home grown forage and mineral could be the only feeds needed. Medium and high quality forages are a good source of many important minerals, such as calcium, phosphorus, potassium, and sulfur, and the important vitamins A and E, but they are usually deficient in salt, and the trace minerals copper, zinc, and selenium. Traditionally producers have used trace mineralized salt (red salt), “sulfur blocks” (yellow salt), or white salt, but they are not to be recommended in any situation because they contain insufficient copper and have no selenium. The copper in these products is also from copper oxide which has low availability; copper sulfate is the supplement of choice. Copper carbonate and tri-basic copper chloride are other inorganic sources with high availability. The yellow salt does provide sulfur, but it is more likely that sulfur will be too high in our systems and it is almost never deficient. The white and yellow salt have no trace minerals at all and should never be used.
Sometimes, producers provide both salt and a complete mineral supplement, but this is not recommended because some animals may consume little of the complete supplement. Free choice supplements such as protein blocks are almost never recommended when grass tetany is a potential problem (unless they are “high-mag”), because they contain salt and will reduce the intake of the mineral supplements.
Due to high levels of potassium and marginal levels of magnesium in high quality forages, they generally predispose both lactating cows and growing calves to grass tetany. Because of this we often recommend the year-round use of a high magnesium free choice mineral supplement. Our recommendation is that these supplements be consumed at 4 oz/animal unit/day, and should contain 10-14% magnesium, .09% copper from copper sulfate (.13% copper for Simmental and other exotic breeds), .18% zinc and .0026% selenium. A lower cost (low phosphorus) high magnesium supplement can be used if phosphorus is known to be adequate. Also, molasses/magnesium blocks are available for use on farms with a high incidence of grass tetany.
Growing cattle such as stocker cattle and replacement heifers should be provided with a free-choice mineral with an ionophore (Bovatec or Rumensin). These types of supplements will pay for growing cattle on high quality diets even though they seem expensive “by the bag”. Using an ionophore mineral will pay about a $.10 return in extra gain for each $.05 invested. With high quality forages and an ionophore containing mineral, heifers can frequently be developed without grain supplementation. Bovatec should never be recommended for brood cows, while Rumensin can be used for brood cows.
New feed additives such as “chelated” trace minerals (like zinc methionine) increase the mineral cost by about the same amount as the ionophore, but are supported by very few research studies compared to the ionophores. They are recommended with great caution because many producers have been disappointed with the results, and often they are inadequate in magnesium, copper or other needed minerals.
Winter Feeding Management
Regardless of the system, there will be a time when the cattle are being fed hay, and this is a logical time to save some money. Sampling the hay on hand and analyzing it for nutritional quality will allow the producer to meet the nutritional requirements of all the groups with minimal supplement. During the winter there should be some high quality grazing and that should be allotted to the developing replacement heifers and/or the first calf heifers. The mature cows will be getting the lowest quality hay up until they calve, and then will be fed medium to high quality hay until grazing is available. Having a plan for the wintering period can greatly reduce cow costs, up to $40/head in some cases. Small and medium sized producers should consider purchasing rather than making hay, and should maximize the use of stockpiled forage to minimize the amount of hay needed. They should also consider using deep stacked broiler litter as an alternative to hay, as this will help reduce feed cost and build pasture fertility.
Putting together a practical grazing system takes a lot of planning and goal setting. Often these systems fail because the producer failed to do a good job of deciding what they were doing and why. The management of a forage system takes time and effort, and it is important that the producer set up a system that is best suited for their management style.
Belum ada komentar.