John E. Shirley

Characterization of ruminal dynamics in Holstein dairy cows during the periparturient period

We used four pregnant Holstein cows to delineate ruminal adaptations as cows transitioned from one lactation to the next. Cows were fed typical diets through far-off and close-up dry periods and lactation. We measured ruminal characteristics on day 72 (late lactation), 51 (far-off dry), 23 and 9 (close-up dry) prepartum and on days 6, 20, 34, 48, 62, 76 and 90 postpartum (early lactation). Measurements included: ruminal fill (weight of actual contents), ruminal capacity (volume of rumen when fully filled), digestibilities and ruminal passage rates. Ruminal capacity tended to increase linearly during early lactation but was stable during dry and transition periods. Both total and liquid fill decreased linearly during the dry period, increased across parturition, and increased linearly through early lactation. Dry matter fill decreased as cows were fed the close-up diet at day 23 prepartum then increased near parturition and continued to increase across early lactation. Solid passage rate was greatest when cows were fed the close-up diet, and decreased throughout the transition period. In lactation, solid passage rate responded quadratically with peak at day 48 followed by decreases through day 90 postpartum. Liquid passage increased linearly across the transition period. Total tract organic matter digestibilities increased linearly over the dry period with significant increases prior to or immediately after parturition, then they remained relatively stable over early lactation until they increased at day 90. Fibre digestibilities demonstrated quadratic responses over early lactation, being higher on day 6 and day 90 than at other times. Starch digestibilities decreased linearly across both the dry and transition periods with decreases in lactation until day 62 followed by increases until day 90. High producing lactating dairy cows go through a multitude of ruminal adaptations, in terms of digestion, passage, capacity and fill, as they transition from one lactation to the next.

Comparison of full-fat corn germ, whole cottonseed, and tallow as fat sources for lactating dairy cattle.

Twenty-four multiparous Holstein cows (124 +/- 39 d in milk; 682 +/- 72 kg of body weight) were used in 6 simultaneous 4 x 4 Latin squares to evaluate full-fat corn germ as a fat source for lactating dairy cows. Experimental diets were a control (containing 28% ground corn, 23% alfalfa hay, 19% wet corn gluten feed, and 10% corn silage, dry matter basis), and 3 diets with either whole cottonseed (WCS), tallow (TAL), or full-fat corn germ (FFCG) added to provide 1.6% supplemental fat. Cows were fed twice daily for ad libitum intake. Dry matter intake, milk yield, and energy-corrected milk did not differ among diets. Efficiency of milk production (energy-corrected milk/dry matter intake) was greater for cows fed WCS than for cows fed the control, TAL, or FFCG. Milk fat percentage from cows fed FFCG was less than that of cows fed WCS or the control, but was similar to that of cows fed TAL. Milk protein percentage was less for cows fed FFCG than for those fed the control. Total saturated fatty acids were less in milk from cows fed fat sources, and cows fed WCS and TAL had greater saturated fatty acids in milk than did cows fed FFCG. Unsaturated fatty acids were greater in milk from cows fed FFCG than in milk from cows fed the control, WCS, or TAL. The cis-9, trans-11 conjugated linoleic acid content was greater in milk from cows fed WCS, TAL, and FFCG than from cows fed the control, and it was greater in milk from cows fed FFCG than in milk from cows fed WCS or TAL. These results indicate that FFCG can be used effectively as a fat source in diets for lactating dairy cattle.

Impact of dried seaweed meal on heat-stressed lactating dairy cattle

Twenty-four lactating Holstein cows were used to determine the production response to the inclusion of brown seaweed in the basal diet during summer heat stress. Cows were blocked by lactation number, days in milk, and energy-corrected milk and then allotted to either a control or control + brown seaweed diet. Cattle on the brown seaweed diet were fed 4 ounces per cow per day for 7 days , and then 2 ounces per cow per day for 14 days, before the start of the experiment. All cattle were housed in a tie-stall barn, fed individually, and milked twice daily. Cows fed brown seaweed produced more (P<0.01) milk (77.6 vs 73.8 lb) and milk protein than controls did. But the addition of brown seaweed did not reduce respiration rates, rectal temperature, or rear-udder skin temperature. This indicated a similar heat-stress response for treated and control cows. Other studies have shown a reduction in respiration rates and body temperature when stressed cattle were fed brown seaweed. Further investigation is necessary to determine the factors that resulted in the observed milk and milk-protein responses in this study.

Extruded-expelled cottonseed meal (express) as a source of protein and fat for lactating dairy cows

Twenty-four Holstein cows were used in six 4×4 Latin squares to evaluate the effects of substituting extruded-expelled cottonseed meal (ExpressTM) for whole cottonseed and solvent soybean meal in diets for lactating cows. No differences were observed in milk and milk component yield among treatments. Percentages of fat, protein, solids-not-fat, and lactose in milk were similar among treatments. Replacing whole cottonseed with ExpressTM tended to reduce milk urea nitrogen but had no effect on milk protein percentage or yield. Cow acceptability of ExpressTM was excellent throughout the 84-day study conducted between late June and September when ambient temperature exceeded 100EF for 35 days. Long-term storage of ExpressTM in a commodity barn was not a problem. In vitro analysis of ExpressTM revealed that it contains approximately 75% rumen undegradable protein (RUP) with an intestinally absorbable dietary protein value of 53.4%. ExpressTM is an excellent source of RUP, and the protein fraction is highly digestible in the small intestine.

Comparative value of full-fat corn germ, whole cottonseed and tallow as energy sources for lactating dairy cows

We used 24 multiparous Holstein cows in 4 × 4 Latin square design to evaluate full-fat corn germ as a replacement for whole cottonseed and tallow in total mixed diets for lactating dairy cows. Experimental diets on a dry matter basis were: 1) control 3.5% fat; 2) whole cottonseed 5.1% fat; 3) tallow 5.1% fat; 4) full-fat corn germ 5.1% fat. Diets were fed as total mixed rations typical of that fed on commercial dairy operations. Cottonseed meal and cottonseed hulls were included in the control, tallow, and full-fat corn germ diets to balance for fiber and protein fractions equal to those in the whole cottonseed diet. Dry matter intake, milk production, and energy corrected milk did not differ among the diets. Milk from cows fed full-fat corn germ contained less fat than milk from cows fed whole cottonseed but was similar to that of milk from cows fed control or tallow diets. Milk protein percentage was lower for cows fed full-fat corn germ than those fed control, but similar to cows fed whole cottonseed or tallow. Percentage milk lactose did not differ among dietary treatments. Cows fed WCS produced more pounds of milk fat than cows fed full-fat corn germ or tallow, but protein and lactose yield did not differ among the diets. Cows fed whole cottonseed produced milk more efficiently than cows fed control, tallow, or full-fat corn germ. Unexpectedly, efficiency of energy corrected milk production was not improved by tallow and tallow did not depress dry matter intake. Somatic cell count did not differ among experimental diets. Urea nitrogen concentration was lower in milk from cows fed full-fat corn germ and tallow than those fed whole cottonseed. All diets led to gains in body weight.

Performance of holstein cows fed wet corn gluten feed or soyhull-steep liquor pellets during early lactation

Complete lactation milk yield is positively related to peak milk yield, which generally occurs by 50 to 60 days in milk. Nutrition limits peak milk yield because of inadequate dry matter intake. Body tissue mobilization and ruminal adjustments are made in an attempt to meet nutrient deficits. Therefore, it is imperative during early lactation to provide dietary ingredients that are highly digestible in order to enhance nutrient availability. A critical issue in diet formulation is balancing fiber content to prevent ruminal acidosis. Short-term studies (28-day period) conducted at Kansas State University with wet corn gluten feed (WCGF) and a pelleted feedstuff made by combining soy hulls and condensed corn steep liquor (SHSL) indicated that these feedstuffs improve dry matter intake and maintain ruminal pH. The purpose of this study was to evaluate the response of dairy cows to WCGF and SHSL during the first 90 days in milk.

Evaluation of wet corn gluten feed as an ingredient in diets for lactating dairy cows

Thirty-two Holstein cows were used in two 2×2 Latin squares with 28-day periods to evaluate the effect of including wet corn gluten feed in diets for lactating dairy cows. Wet corn gluten feed (WCGF) was fed to cows housed in freestalls at 20% of the diet dry matter. Cows fed WCGF consumed more dry matter, and produced more milk and more energy-corrected milk than cows fed the control diet. Production efficiency was not different between diets. The percentages of fat and protein in milk were not different between diets, but yields of all milk components were improved by including WCGF in the diet. Body weight and condition score were not affected by treatment. Plasma glucose, total amino acids, and urea nitrogen were similar between cows fed the control and WCGF diets. WCGF is an excellent feed for lactating dairy cows when included in the diet at 20% of the dry matter. Further studies are warranted to determine the upper limits of its dietary inclusion.

Assessment of mastitic infection in bovine milk using ATP bioluminescence

Few choices exist for a mobile, rapid, and nonsubjective assessment of mastitic infection in bovine milk. This project evaluated the effectiveness of using the Biotrace® raw milk quality ATP bioluminescence assay to serve this role. Milk samples with various somatic cell counts (13,000 2,500,000) and signs of mastitic infection were obtained from the Kansas State University Dairy Teaching and Research Center. Within 24 hr, raw milk samples were evaluated for microbial numbers and relative light units (RLU). The printed test procedure was modified to evaluate accurately clinical mastitic milk samples. As somatic cell count increased in raw milk, the RLU value increased. In addition, RLU values differentiated among milk samples with various levels of mastitic infection (none, subclinical, and clinical). Repeatability of the ATP bio-luminescence method was very good (CV = 4.76%). These results suggest that the Biotrace® raw milk quality test kit can served effectively as a nonsubjective, rapid assay to determine the degree of mastitic infection in bovine milk.

Factors affecting titratable acidity in raw milk

The value of titratable acidity (TA) as an indicator of raw milk quality has been challenged recently, because milk is refrigerated within minutes after it leaves the cow until it reaches the consumer. Also, high milk protein may interfere with the test or confer falsely high TA values. Samples of milk containing <2.8% protein to >3.8% protein were used to examine the impact of protein on TA. The effects of milk age and bacterial counts also were investigated. Titratable acidity increased as milk protein content increased but the influence of bacterial populations and age were much more dramatic. As bacterial counts increased, TA values surpassed an acceptable level (upper maximum at .17%) for the KSU Dairy Processing Plant. At the same time, as raw milk increased in age, TA increased to the upper level of acceptability (.17%). Thus, TA appears to be a valid method of evaluating raw milk quality even though it can be influenced by the protein content.; Dairy Day, 1996, Kansas State University, Manhattan, KS, 1996;

Performance of mid-lactating dairy cows fed a grain sorghum-soybean silage base diet

Whole-plant silage from intercropped grain sorghum and Williams 82 soybean was compared to corn silage in a mixed diet for mid-lactation dairy cows. Cows fed the grain sorghum-soybean silage yielded 45.13 lb and those fed corn silage yielded 44.05 lb of fat (4%)-corrected milk daily. Milk yield, milk fat, and milk lactose percentages were similar between cows fed the two silages. Protein and solids non-fat percentages for the cows fed the corn silage diet were .09 and .06 units greater than those of cows fed the grain sorghum silage. Cows fed the corn silage tended to gain more (+105.8 lb) than those fed the grain sorghum-soybean silage (+95.2 lb). We conclude that, if the cost for producing intercropped grain sorghum and soybean silage (ton/acre) is at least similar to that of producing corn silage, the intercropped grain sorghum and soybean silage can be substituted for corn silage in a mid-lactation dairy cow diet.