Buckeye Dairy News : Volume 2 Issue 7

  1. ROASTED SOYBEANS AND COPPER INCREASE SPONTANEOUS OXIDIZED MILK FLAVOR

    Jennifer S. Timmons, M. S., Donald L. Palmquist, Ph.D. 
    Department of Animal Sciences

    Ration composition of lactating cows has been altered over recent years to supply the energy required to support enhanced milk production. One way to accomplish this is to supplement with a fat source such as roasted soybeans. Roasted soybeans contain approximately 20% fat that is high in polyunsaturated fatty acids: 50% to 55% linoleic acid (18:2) and 6% to 8% linolenic acid (18:3)Some of the unsaturated fatty acids in roasted soybeans bypass the rumen and are digested in the small intestine; these are directly incorporated into the milk fat. The polyunsaturated fatty acids are highly susceptible to oxidation; oxidation of milk fat leads to development of spontaneous oxidized flavor (SOF) in milk. The flavor in some cases occurs instantaneously from the cow and intensifies in susceptible milk during refrigerated storage Milk may taste normal at the farm, but develops a flavor characterized as tasting metallic, cardboardy or tallowy with time. The off-flavor may cause consumer rejection, a shorter shelf life and a decrease in the demand for milk. In 1996, Reiter Dairy / Dean Foods contacted OARDC about this off-flavor problem that had lead to rejection of tanker loads of milk. An initial survey showed that polyunsaturated fatty acids were higher in milk from herds fed whole soybeans. OARDC then obtained funding through Dairy Management Incorporated to investigate causative factors related to off-flavor development and to explore possible preventative measures. A commercial field study was performed to determine the role of roasted soybeans (RSB) and milk components in off-flavor development. Twenty commercial dairy farms in the vicinity of Wooster, Ohio were selected based on the feeding of roasted soybeans. Herd size ranged from 35 to 432 head with a RHA of 14,500 to 30,800 lbs/yr. Cows in herds were fed typical Ohio diets of haylage, corn silage, high moisture corn, and a range of 0 to 15% of the diet dry matter as RSB. Bulk tank milk was sampled after the AM milking prior to milk tanker pickup and analyzed for milk fat composition, vitamins, minerals and off-flavor development on 0, 3, and 8 days post-sampling. The development of SOF was related to an increase in the polyunsaturated milk fatty acids (linoleic and linolenic acids), caused by the feeding of RSB, a decrease in milk antioxidants (vitamin E and beta-carotene) with increasing time of storage, and increased concentrations of pro-oxidants (copper).

    From the data an equation was developed to predict the development of off-flavor at 8 days post-sampling (approximate time for fluid milk to be bottled, shelved, and purchased by the consumer). The development of SOF was found to be predictable, with one half of the variation in flavor attributed to the amounts of xanthine oxidase (a pro-oxidative enzyme), copper and polyunsaturated fatty acids in the milk. According to these prediction equations, feeding RSB at 15% of the diet DM in the presence of low copper from feed and water would not develop off-flavor. However, in the presence of high copper the amount of RSB (% of diet DM) would need to be decreased below 15% of diet DM to prevent the development of off-flavor. Dairy processors using the prediction equation could pool milk according to its potential for development of SOF. Milk likely to produce oxidized flavor could be converted to alternative uses and milk with low susceptibility to oxidation could be used for fluid milk. These measures should increase shelf life of milk and diminish consumer rejection of milk due to off-flavor. It should be noted that spontaneous oxidized milk flavor is not a wide-spread problem currently because of the low concentration of polyunsaturated fatty acids in the milk supply (3 - 8%); further, homogenization greatly protects against oxidized flavor development. However, the potential for off-flavor development exists, especially with the increased feeding of RSB as a bypass protein and a fat source. Therefore, the cost of potential dumped milk must be weighed against the advantages of feeding high levels of RSB. Farmers feeding RSB need to be aware of the potential of milk with higher unsaturation to develop off-flavor and the repercussions this may have on the dairy industry in the future. 

  2. Now that the Forages are Harvested

    Maurice Eastridge, Ph.D. 
    The Ohio State University 
    Department of Animal Sciences 
     

    • Sum up the quantity of forage available on the farm (supply) and determine tons needed until next harvest season (demand) to identify if hay will need be to purchased or the rations will be to be balanced with less forage.

    • If purchases are needed, buy NOW! Price will be higher later and consider the economies of purchasing large quantities, which may necessitate neighbors purchasing loads of hay together.

    • Now is the time to consider contacting for grain and other concentrate ingredients. Minimize the risk of feed prices by contracting. Seek bids from two or more companies and make sure they are aware that competition exists for your business.

    • If possible, let silages ferment for two to four weeks before feeding.

    • Forages need to be analyzed NOW for nutrient composition. Considerable variation in composition of corn silage may occur this year across the state because of the variable rainfall.

    • Grain (moist and damaged kernels) and corn silage (relatively dry) are at high risk for mycotoxins. If mycotoxins are suspected, analyze for their presence so feeding practices can be adjusted, if necessary, before clinical symptoms are apparent.

  3. Handling Dairy Manure

    Richard Stowell, Ph..D. 
    Department of Food, Agricultural, and Biological Engineering

    A progressive dairy producer must consider ways of handling and managing manure that will prove reliable, efficient and economical into the coming years. Unfortunately, there is no single system of choice that will satisfy the needs of the variety of operations in place today or being planned. Experience and research have improved our ability to evaluate systems and make recommendations, however, and I will summarize a few of those key points.

    The choice of bedding material is critical to the implementation of a good manure handling system. Changing a system of facilities to handle manure that is laden with a bedding material that was not accounted for in the systems design is very frustrating and potentially costly, if not unworkable.

    The design of stall bed used in freestalls largely determines the bedding material that is selected. Two stall-bed designs have risen to the top as the choices of managers seeking cow comfort: the deep bed of sand and the baffled mattress with a covering of loose bedding, usually wood shavings or some other organic material. On the basis of cow comfort and performance alone, sand-based stalls have advantages over their mattress-based counterparts when given similar management attention. Producers need to evaluate (obtain an evaluation of) the expected costs/benefits of each of these designs to cow performance on their own operation.

    Also, consider the available and preferred means of applying manure onto cropland. If all or most of the manure must be pumped a long distance, irrigated or injected, sand must be separated from the manure stream or mattresses should be used instead of sand-based stalls. On the other hand, if all or most of the manure is to be handled using a front-end loader and spread using a box or V-spreader, there is little or no advantage of handling loose manure from mattress-based stalls. In most cases, the available options for handling manure lie somewhere between these extremes, meaning either stall-bed design and bedding material could be used and comparisons should be made on an individual, system basis that includes producer preferences.

    Given the bedding material, a handling system can be put together that suitably matches manure characteristics with prioritized facility and management needs. Sand-laden manure should be handled in one of the following ways:

    • Undiluted, within a covered, concrete storage,

    • In two or three steps (skim-and-haul) as liquid and solid, or as liquid, semi-solid and solid materials, using a storage with a concrete bottom and ramp, or

    • As a well-diluted liquid with the sand removed and handled separately.

    Manure from freestall barns having mattress-based stalls can be handled in several ways. Opportunities exist to utilize gravity-flow transfer systems, centrifugal pumps, and slatted floors. The primary considerations revolve much less around the manure itself and more around labor requirements, local topography, and specific manure management constraints.