Expeller soybean meal as a source of rumen undegradable protein for lactating dairy cows

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Summary
Dietary UIP is required by genetically supe- The loss of meat and bone meal as a source is insufficient to supply the quantity of amino of high quality protein for lactating cows creates acids required to maximize milk production. an increased need for nonanimal sources. Fifty-Fishmeal, blood meal, and meat and bone meal six Holstein cows were used to evaluate expeller are recognized as high quality sources of UIP. soybean meal as a source of rumen undegradable They are used commonly to increase the UIP intake (by-pass) protein for high producing cows.
percentage in diets for high producing cows Expeller soybean meal tended to improve 3.5% during early lactation. In addition, diets containfat-corrected milk yield and increased milk fat ing elevated UIP of high quality generally will percentage relative to diets containing either support milk production at a lower total dietary solvent soybean meal or a meat and bone crude protein than diets low in UIP. meal:blood meal mixture. In contrast, the protein percentage in milk was depressed signifi- The purpose of this study was to determine cantly when cows were fed expeller soybean if expeller SBM, containing 50% of the crude meal compared to animal protein. A limiting protein as UIP, could replace a blend of blood amino acid (possibly methionine) is implicated. meal and meat and bone meal or solvent SBM as (Key Words: Lactating Cows, UIP, Expeller Soybean Meal.) Procedures

Introduction
Fifty-six Holstein cows were utilized to A previous study at Kansas State University as a source of UIP. A blend of blood meal and determined that expeller soybean meal (SBM) meat and bone meal was used as a standard for contained 50% undegradable intake protein comparison. All cows were fed the high-group (UIP) and improved the efficiency of milk pro-herd mix normally used at Kansas State Univerduction when substituted for solvent SBM in sity for the first 28 days postpartum and then diets fed to dairy cows during mid-lactation. assigned to one of the following diets: 1) 18% Further, plasma amino acids were elevated in crude protein, 35% UIP from solvent SBM; 2) cows fed the expeller SBM relative to those fed 16% crude protein, 35% UIP from solvent SBM; solvent SBM. These data suggest that expeller 3) 16% crude protein, 40% UIP from expeller SBM improved the protein status of dairy cows. SBM; and 4) 16% crude protein, 40% UIP from Although this improvement did not translate into a blood meal-meat and bone meal blend. The fat improved milk production, less feed was re-content of the diets was equalized with tallow. quired to produce a pound of milk. This obser-Alfalfa hay and corn silage were used for the vation indicates that the diets containing expeller forage portion of the diets and shelled corn was SBM supplied protein in excess of the mammary the primary grain. Diets were evaluated for 84 gland's need to support milk production during days. mid-lactation. rior dairy cows because rumen microbial protein a source of UIP. evaluate mechanically processed expeller SBM The diet with 18% CP/35% UIP served as a crude protein. Other published reports also positive control with which we expected milk indicated that high producing dairy cows respond production to be optimized. The 16% CP/35% positively to an increase in UIP at lower total UIP diet was expected to yield less quality milk dietary protein. because it supplied insufficient quantities of amino acids to the cow and served as a negative Milk composition among treatments was control. The final two diets with 16% CP and interesting in that the percent fat and protein 40% UIP were expected to yield improvements tended to move in opposite directions. Expeller in performance relative to the negative control SBM increased (P<.05) milk fat percentage that were related directly to the ability of the compared to animal protein and tended (P=.16) protein sources (expeller SBM and the to increase milk fat percent compared to the 18% blood/meat blend) to supply amino acids to the protein/35% UIP diet. In contrast, protein percows.
centage was depressed in milk from cows fed Cows in dietary treatments were balanced protein (P<.01), 18% protein/35% UIP (P<.05), for parity, milk production, and body condition and 16% protein/35% UIP. The improvement in based on pretreatment performance. Treatment milk fat percentage resulted in a numerical incomparisons included milk production, dry crease in 3.5% fat-corrected milk from cows matter intake, body condition change, body receiving the expeller SBM diet compared to the weight gain, and efficiency (lb of milk per lb of other three diets. Total milk fat (lb/day) was feed dry matter consumed). Body weight was also highest for the expeller SBM diet. Although measured on 2 consecutive days at the beginning milk protein percentage was depressed by the and end of the study and weekly during the expeller SBM diet, total milk protein (lb/day) study. Body condition was scored weekly.
was similar among the three SBM diets. The Daily feed intake and milk production were animal protein blend led to higher total milk recorded, and milk composition (protein, fat, protein (lb/day) than the expeller SBM. lactose, and solids-not-fat) was determined weekly. Blood samples were obtained during the Both expeller SBM and the animal protein pretreatment period and every 3 wk during the blend increased (P<.05) total plasma amino acids study to evaluate energy and protein status.
relative to the negative control (16% solvent

Results and Discussion
highest for the 18% protein diet and, among the Compositions of the experimental diets are protein blend. The expeller SBM was effective presented in Table 1. Tallow was used to equal-in delivering amino acids to the bloodstream, but ize fat content (energy density) across diets the depressed milk protein percentage indicates because solvent SBM contained 1.5% fat, that amino acids were not translated into milk expeller SBM contained 5% fat, and meat and protein. The expeller SBM diet may have been bone meal contained 10.4% fat. deficient in at least one essential amino acid.
Cows fed expeller SBM consumed slightly fat percentage was greater in milk from cows fed more dry matter (Table 2) than cows fed the the expeller SBM diet relative to the other diets. other diets. Milk production was numerically Elevated milk fat percentage has been observed greater from cows fed diets containing 40% UIP in diets deficient in one or more amino acids. than from those fed diets containing 35% UIP. Milk production was similar for cows receiving In conclusion, expeller SBM tended to the 18% and 16% crude protein diets containing improve milk and milk fat production but 35% UIP. These results are consistent with depressed milk protein relative to diets conrecommendations of the National Research taining a mixture of meat and bone meal and Council for diets containing approximately 16% blood meal. Methionine is suggested as being expeller SBM compared to cows fed animal SBM) diet (Table 2). Plasma urea nitrogen was 16% protein diets, was lowest for the animal This conclusion is strengthened by the fact that limiting in heat-treated soy diets. Additional work is underway to verify this hypothesis. If methionine is limiting, the inclusion of corn gluten meal (an excellent source of methionine) in diets containing expeller SBM might improve milk protein percentage.  Means within a row without a common superscript letter differ (P<.05). x,y,z