Formulating Dairy Rations with Neutral Detergent Fiber. 1. Effect of Silage Source

Alfalfa and corn silages were evaluated as sources of forage fiber in diets for early lactation cows formulated to contain equal amounts of neutral detergent fiber. Diets were designed to contain 32% neutral detergent fiber and 17% crude protein. Twenty-four cows were assigned on the basis of parity and calving date to one of three experimental diets fed as complete mixed rations. Silage contents of the three complete mixed rations on a dry basis were 54.8% alfalfa silage, 67.4% corn silage, and 60.1% of a 1:1 combination of these two silages. The remainder of the experimental rations was composed of corn, soybean meal, minerals, and vitamins. Experimental rations were fed for a 9-wk period, which was preceded and followed by 3-wk periods when all cows were fed a standard diet. Using the average of pre- and postexperimental period means as a covariate, no significant differences were found among the experimental means for actual milk and fat-corrected milk yield or milk composition. Daily dry matter intake as a percent of body weight was lower for cows fed the corn silage-based diet. There were no differences in milk production between alfalfa silage and corn silage when diets contained similar concentrations of neutral detergent fiber. Rations containing 32% neutral detergent fiber were adequate for cows in early lactation producing approximately 30 kg of 4% fat-corrected milk/d.     

Varying dietary fiber for lactating cows fed corn and barley silages

Seventy-five lactating cows were in three experiments to determine the effect of dietary fiber content on ration intake, milk and milk fat production, ration digestibility, nitrogen utilization, and ruminal volatile fatty acids. With corn or barley silage as the source of forage, four treatment groups consumed rations averaging 11.8, 14.5, 17.5, and 20.6% crude fiber and 14.3, 17.5, 20.0, and 23.9% acid detergent fiber dry basis. Fiber intake was controlled by the amount and fiber content of concentrate offered or by silages with different grain content. With corn silage, dry matter intake was not altered by dietary fiber, but dry matter intake was lower when additional fiber was fed with barlev silage. Linear regressions best described effects of dietary fiber on milk production and milk fat content. Milk production declined .39 and .36 kg and milk fat test increased .072 and .067% for each percentage increase in crude and acid detergent fiber. Ration digestibility, determined by lignin ratio, was less for barley silage than corn silage. Narrowing acetate: propionate ratios were evident when dietary fiber was lowered. From these experiments with silage based rations, either crude or acid-detergent fiber content of forage adequately describes feeds to serve as a basis for practically balancing rations for lactating cows.     

The effects of feeding rations that differ in fiber and fermentable starch within a day on milk production and the daily rhythm of feed intake and plasma hormones and metabolites in dairy cows

A daily pattern of feed intake, milk synthesis, and plasma metabolites and hormones occurs in dairy cows fed a total mixed ration once or twice a day. The objective of this study was to determine if feeding multiple rations within a day, complementing these rhythms, would improve milk production. Twelve Holstein cows were used in a replicated 3 × 3 Latin square design with 21-d periods. Cows were housed in tie stalls with feed tubs, and feed weight was recorded every 10 s for observation of feeding behavior. Rations were a low fiber and high fermentable starch ration [LFHS; 27.4% neutral detergent fiber (NDF) and 31.7% starch based on 55.7% corn silage and 14.1% steam-flaked corn], a high fiber and low fermentable starch ration (HFLS; 31.7% NDF and 22.3% starch based on 44% corn silage, 26.3% alfalfa haylage, and no steam-flaked corn), and a total mixed ration that was a 1:3 ratio of LFHS and HFLS (30.7% NDF, 24.5% starch). The control treatment (CON) cows were fed the total mixed ration at 0700 h, the high/low treatment (HL) fed HFLS ration at 0700 h and LFHS ration at 2200 h, and the low/high (LH) treatment fed LFHS ration at 0700 h and HFLS ration at 1100 h (LFHS and HFLS rations fed at a 1:3 ratio). No effect was found of treatment on daily milk, but LH decreased milk fat concentration and yield compared with HL (0.2 percentage units and 0.24 kg, respectively). Daily dry matter and NDF intake and total-tract digestibility did not differ between treatments. The HL treatment reduced intake at the morning-conditioned meal after feeding and reduced intake before the evening feeding. A treatment by time of day interaction was found for fecal NDF and indigestible NDF concentration, blood urea nitrogen (BUN), plasma insulin, and fatty acid concentration, and body temperature. The CON and LH treatments increased the daily amplitude of fecal NDF by 1.0 and 1.1 percentage units compared with HL. Plasma insulin was higher in HL than CON at 0100 and 0400 h, but lower at 1300 and 1900 h. Plasma fatty acids were higher for CON than HL at 0700 h and HL was lower than LH at 0400 and 1900 h. Plasma BUN was higher for HL than control at 0100 h, but lower at 1000 h. Body temperature in CON and HL treatments followed a similar diurnal pattern, whereas body temperature for LH was lower than that of HL treatment at 1300 and 2300 h. No daily rhythm was found of fecal indigestible NDF concentration, plasma glucose, or fatty acids detected in the HL treatment, and the amplitude of plasma insulin and BUN was lower for HL compared with CON (70 and 60% decrease, respectively). In conclusion, feeding 2 rations that differ in fiber and fermentable starch modifies diurnal rhythms in dairy cows. Furthermore, feeding a high fiber and low fermentable starch ration during the high intake period of the day may stabilize nutrient absorption across the day.     

No Associative Effects Between Corn and Haycrop Silages Fed to Lactating Dairy Cows

Four first-lactation Holstein cows were used 65 to 177 days postpartum in a 4 × 4 Latin square trial to evaluate possible associative feeding effects between corn and haycrop silages. Nutrient digestibility and nitrogen and energy balances were studied. Diets were concentrate mixture, urea-treated corn silage, and early-cut, wilted haycrop silage in dry matter ratios of 55:45:0, 55:30:15, 55:15:30, and 55:0:45. Rations were offered just below energy balance in each 28-day period. Ration components were fed separately, concurrently, and twice daily. Crude protein in concentrate, corn silage, and hay crop silage dry matter was 16.9, 11.1, and 12.5%. Milk yield (18 to 19 kg) and ration dry matter intake (2.61% body weight) were not significantly different among diets. Apparent digestibility of gross energy, dry matter, protein, and fiber was not different among diets, but fat was more digestible in corn silage. Partition of ingested energy and nitrogen was not affected by treatments except that urine nitrogen was higher in corn silage. No associative feeding effects were significant. The two silages were equivalent in supporting milk production when fed in equal dry matter amounts.     

Dry Matter Intake in Dairy Heifers. 1. Factors Affecting Intake of Heifers under Intensive Management

Effects of body weight, body weight gain, ration acid detergent fiber, neutral detergent fiber, bulk density, and ambient temperature on intake of dry matter and digestible energy were examined using 118 Holstein heifers weighing 100 to 400 kg. Animals grouped according to body weight (100, 200, 300 kg) were fed total mixed rations (corn silage, ground hay, high moisture corn, soybean meal) once daily for 28 d. Rations were balanced to mean body weight according to National Research Council recommendations for protein, vitamins, and minerals and to 85, 95, 105, and 115% of recommended total digestible nutrients. Second order polynomial regression of ration fiber content and density explained 20 and 21% of variation in dry matter intake and 46 and 45% of digestible energy intake. Dry matter intake increased linearly with increasing body weight and gain. Dry matter intake correlated −.42, −.42, and .39 with acid detergent fiber, neutral detergent fiber, and bulk density when neutral detergent fiber was greater than 42% of dry matter and .03, −.03, and −.02 when less than 42%. Predictions of dry matter intake should include body weight, gain, and polynomial terms of ration fiber or ration energy to account for changing metabolic systems controlling intake.     

Evaluation of Sunflower Crop Residue in Rations for Growing Holstein Heifers

Sunflower crop residue, a mixture of stalks and heads, contained 65.4% dry matter, and dry matter was 6.1% crude protein, 66.9% neutral detergent fiber, 56.6% acid detergent fiber, 15.7% lignin, and 12.6% total ash. In vitro dry matter and cell wall digestibilities were 40.6 and 31.4%. Sixteen Holstein heifers (mean weight 247 kg) were assigned to one of four rations containing 0, 8, 16, or 32% sunflower residue (dry matter). Mid-bloom alfalfa hay and a grain mixture (corn, soybean meal, dicalcium phosphate, vitamins A, D, and E) were 30 and 20% of dry matter with corn silage providing the remaining dry matter. Weight gains during a 70-d trial were 1.31, 1.18, .91, and .98 kg/d for 0, 8, 16, and 32% sunflower residue. Dry matter digestibilities decreased with increased sunflower residue in the ration. Ruminal propionate (mol/100 mol total volatile fatty acids) decreased with increasing sunflower residue, resulting in higher acetate-to-propionate ratios. Total volatile fatty acids, ruminal pH, and ammonia concentrations were not different among diets. With proper supplementation, sunflower crop residue was an acceptable roughage up to 32% of total ration dry matter for growing Holstein heifers.     

Utilization of Alfalfa Hay and Alfalfa Silage. 1. Protein Sources in Corn Silage-Based Diets

Different amounts of alfalfa as hay or silage were compared with soybean meal or urea as protein sources for steers fed corn silage-based diets. Source of alfalfa and source by amount interactions were not significant when alfalfa was fed as hay or silage at 32, 63, or 100% of dry matter in trial 1. A highly significant linear response in average daily gain and gain to feed ratio was observed to alfalfa amounts. Daily gain (.90 vs. .87 kg) and gain to feed ratio (.139 vs. .136) were very similar when diets were formulated to meet protein requirements with 32% alfalfa as either hay or silage.In trial 2, supplemental protein for steers fed corn silage was provided by alfalfa hay or silage at 12 or 50% of diet dry matter or by soybean meal or urea. The 12% alfalfa diet contained equal parts of supplemental protein from alfalfa and from urea. Regression analyses indicated that supplementation of either alfalfa hay or silage with urea did not improve utilization of corn silage. Differences in fiber and protein fractions resulting from harvesting and storage of alfalfa as hay or silage do not change the value of alfalfa as a protein source when used in corn silage-based diets.     

Urea on Flaked Soybean Hulls as a Protein Replacement for Dairy Cows

In Experiment I a Latin square design was used to study the utilization of urea nitrogen adsorbed on flaked soybean hulls in normal rations of high producing dairy cows. Concentrates containing urea, urea with supplemental minerals, or soybean meal as the protein supplement were fed with corn silage and alfalfa in a total ration of approximately 17% crude protein. Both urea concentrates contained 2.7% urea. Animals fed urea and soybean had similar milk yields (28.7 and 27.9 kg/day), milk protein, and digestible dry matter intakes. Urea with mineral produced lower milk yield (25.3 kg/day), milk protein, and dry matter intakes, probably because of excessive mineral content. Urea nitrogen of plasma was similar for all three diets. Essential amino acids of plasma were lower for urea than for soybean while for urea mineral the essential amino acids were midway between the other two. In Experiment 2 a switchback design was used to compare the urea-soybean hull concentrate diet of Experiment 1 (17% crude protein) to a negative control diet consisting of its basal components without urea adjusted to 12% protein with wheat bran. Milk yield was 1.2 kg/day higher when the urea diet was fed. Perhaps due to improved urea distribution in the rumen, flaked soybean hulls with urea were effective in maintaining the feed intake necessary for high milk production.     

Sorghum forage in precision-fed dairy heifer diets

Sorghum forage is an alternative crop that is more adapted to drier conditions and more resistant than corn to drought conditions. Thus, sorghum forage maximizes water utilization. The objective of this study was to evaluate sorghum silage (SS), including digestibility and fermentation parameters, in precision-fed dairy heifers. Eight Holstein heifers (13.7 ± 0.6 mo of age and 364.8 ± 17.64 kg of body weight) fitted with rumen cannulas were used in a replicated 4 × 4 Latin Square design; treatments were 4 levels of forage to concentrate ratios (85:15, 75:25, 65:35, and 55:45). Rumen contents were sampled at various times to determine pH and volatile fatty acid concentrations. Dry matter (DM) and neutral detergent fiber (NDF) in situ degradation kinetics were compared between SS and corn silage (CS) diets. Fecal total collection was used to estimate apparent total-tract digestibility. Fecal grab samples at 0, 6, 12, and 18 h after feeding were used to estimate total-tract starch digestibility. Amount of concentrate in the diet affected the time that heifers spent eating as well as rumen pH. When the concentrate proportion of the diet increased, eating time and rumen pH decreased linearly. Total volatile fatty acid concentrations were not affected by treatment, but butyrate increased as the proportion of concentrate increased in the diet. Digestibility of DM and starch were higher in diets with lower forage to concentrate ratio, but NDF, acid detergent fiber, and hemicellulose digestibility were not affected. Corn silage had greater DM and NDF digestibility than SS. Also, fractional rate of digestion was faster for CS than SS (2.78 vs. 2.42% per hour, respectively). We conclude that fecal grab samples are suitable for predicting starch digestibility in heifers given the starch levels studied. In addition, SS was an adequate alternative forage in precision-fed dairy heifers with outcomes very similar to CS-based rations.     

Effect of Forage Maturity on Ration Digestibility and Production by Dairy Cows

Mixed grass-legume silages harvested at early and late maturities from the same field were evaluated in three trials to determine maturity effects on ration digestibility when forages were fed alone or in complete rations. In situ dry matter disappearance was examined using a rumen-fistulated steer. Rate of disappearance of potentially digestible dry matter was reduced for forage of greater maturity (−.0504 h⁻¹ for early versus −.0316⁻¹ for late cut silage). Nonlactating cows were used to determine forage digestibility. Apparent dry matter (69.2 versus 54.2%), acid detergent fiber (70.8 versus 52.7%), neutral detergent fiber (74.1 versus 55.9%), and crude protein (66.2 versus 45.6%) digestibilities were higher for early cut forage.Ration digestibility and milk production response were also measured. Concentrate to forage ratios necessary to meet energy requirements were 60:40 and 78:22 for diets containing early or late cut forage, respectively. Digestibilities of acid detergent fiber (60.2 versus 42.5%) and neutral detergent fiber (62.0 versus 52.7%) were higher for lactating animals consuming ration containing early cut forage. Milk yield and composition was not affected by diet. For each day of advancing forage maturity, approximately 1% more concentrate was needed in the total ration.     

Eating Rate of Lactating Cows Fed Four Physical Forms of the Same Grain Ration

Eleven cows in midlactation were fed grain rations in pelleted (.4 cm diameter), coarse (premix pellet with cracked corn), Ett® (crumbled pellet), or meal forms. Eating rate was measured during morning feedings for 5 consecutive days following a 2-day adjustment. Eating rate was computed by 4-min intervals during the 28-min eating period. Fat-corrected milk production, intake of corn silage, and of alfalfa hay averaged 19.3, 15.1, and 3.4 kg per day for all cows. Differences of ration intake were greatest during the first 8 min. Rate of eating was most rapid for the pelleted ration followed by coarse, Ett®, and meal forms. Total 28-min intake paralleled intake during initial 8 to 12 min. Physical form influenced ration intake initially when eating time was limited. Subsequent intake reduction probably is related to physiological feedback which also may be affected by physical form of the ration.     

Brown Midrib Corn Silage in Dairy Cattle Rations,

Two groups of 12 Holstein cows past peak lactation were fed complete mixed diets containing either brown midrib corn silage or its normal genetic counterpart. All cows were fed a standardization ration containing another corn silage prior to and after the experimental period. Performance during the experimental period was expressed as deviation from standardization. Cows fed brown midrib silage produced .66 kg more milk per day that tested .28 percentage units less fat during the 4-wk experimental period than during standardization. Control cows produced .10 kg more milk per day in the experimental period as compared to standardization without difference in fat test. On a fat-corrected basis (4%) there was no difference in milk yield between treatments.     

Yields and Nutritive Value of Cuttings of Permanent Pasture Harvested as Dried Forage

Four .12-ha plots were outlined in an area of permanent pasture. Two were harvested initially on May 17 and two on May 24. One plot from each then was treated with nitrogen at 56 kg/ha. Three subsequent cuttings were when plant regrowth had reached 25 to 30 cm or when vegetative growth had ceased. Forages were sampled at cutting and after drying in the field and later under a barn roof. Material harvested on common cutting dates was combined and fed to four lactating cows in a series of digestion trials. First harvest on May 17 resulted in higher seasonal yield of dry matter than that for the May 24 cutting, 7,219 versus 5,687 kg/ha. Pasture cuttings averaged 17.2% crude protein, 28.6% acid detergent fiber, and 73.4% in vitro digestibility. Animal digestibilities of the dried pasture cuttings were high for first and fourth cuttings (digestible dry matter 76 to 79%) and lower for midsummer harvest (digestible dry matter 56%).     

Corn Silage Partially Replacing Short Alfalfa Hay to Optimize Forage Use in Total Mixed Rations for Lactating Cows

We theorized that adding corn silage to a total mixed ration with alfalfa hay as the sole dietary forage would improve nutrient intake and chewing activity and thereby improve rumen fermentation and milk production. The objective of this research was to determine the effects of partial replacement of short alfalfa [physically effective (pe) neutral detergent fiber (NDF) >1.18 mm (peNDF_>1.18) = 33.2%] with corn silage (CS, peNDF_>1.18 = 51.9%) in yellow grease-supplemented total mixed rations on feed intake, chewing behavior, rumen fermentation, and lactation performance by dairy cows. Four multiparous (138 ± 3 d in milk) and 4 primiparous (115 ± 10 d in milk) Holstein cows were used in a 4 × 4 Latin square design experiment with four 21-d periods. Each period had 14 d of adaptation and 7 d of sampling, and parity was the square. Treatments were diets [dry matter (DM) basis] with 1) 40% alfalfa hay (ALF), 2) 24% alfalfa hay + 16% CS (CS40), 3) 20% alfalfa hay + 20% CS (CS50), and 4) 16% alfalfa hay + 24% CS (CS60). Diets had a forage-to-concentrate ratio of 40:60 on a DM basis. Cows had greater intake of DM and thus greater intakes of net energy for lactation, NDF, and peNDF when CS partially replaced alfalfa hay. Replacing alfalfa hay with CS increased daily eating and chewing times in all cows, and increased rumen pH at 4 h postfeeding in multiparous cows. Apparent total-tract digestibility coefficients for crude protein (CP) and NDF were not different among cows fed ALF, CS40, and CS50, but were lower for CS60 than for ALF. Energy-corrected milk yield was greater for CS40 and CS60 than for ALF. Milk protein yield was increased when CS replaced 40, 50, and 60% of alfalfa hay. Milk lactose was greater only for CS60, but milk lactose yield was greater for CS50 and CS60 than for ALF. Milk percentage and yield of fat did not differ among treatments. Therefore, CS partially replacing short alfalfa hay increased DM intake, consequently increased net energy for lactation and physically effective fiber intakes, and thus, improved milk and milk protein and lactose yields.     

A Device for Monitoring Silage Effluent Produced in Laboratory Silos

A relatively simple device was constructed and employed for monitoring production of effluent from laboratory silos. In experiments in which laboratory silos were filled (.7 kg) with red clover, barley mixture (25.7% dry matter) or with alfalfa (26.0% dry matter), pressures simulated commercial silos. Significant differences in quantities of silage effluent were obtained when the same forage was subjected to different treatments designed to disrupt plant cell membranes before external pressure was applied. The device potentially is useful for investigating effects of various conditions of ensiling on effluent production during silage fermentation.     

Near Infrared Reflectance Spectroscopic Analysis of Sodium Chlorite-Treated Forages and Other Plant Materials

The ability of near infrared reflectance spectroscopy to measure the fiber content and in vitro rumen digestibility of feedstuffs treated with sodium chlorite was determined. Six hays (alfalfa, tall fescue, orchardgrass, red clover, timothy, and a grass-legume hay), two straws (barley and wheat), four stovers (two corn and two soybean), three hulls (peanut, rice, and soybean), and corn cobs were treated with sodium chlorite at 11 concentrations to give .000 to .394 g of sodium chlorite per g of feed (dried at 60°C). Analysis results for the treated feeds using every third sample as a validation set gave standard errors of analysis and r² as follows for the validation set: protein .6, .99; neutral detergent fiber 3.2, .95; acid detergent fiber 2.2, .95; lignin 1.5, .92; hemicellulose 3.1, .91; total carbohydrate 3.4, .94; cellulose 1.9, .94; digestible ADF 6.8, .92; digestible NDF 5.8, .95; and total digestible organic matter 4.0 and .96. These values were similar to those generated for a second set of untreated feeds (67 samples of 5 feeds), showing that treatment did not reduce the validity of using near infrared reflectance spectroscopy to predict feed quality. Studies involving various calibration sets showed that satisfactory results could be obtained using as few as 3/16 of the treated feeds as the calibration set.     

Extruded Soybeans and Corn Gluten Meal as Supplemental Protein Sources for Lactating Dairy Cattle

Holstein cows in early lactation were used to compare three combinations of extruded whole soybeans and corn gluten meal to soybean meal. Treatments were (as a percentage of supplemental crude protein) 100% soybean meal; 75% whole soybeans extruded at 149°C, 25% corn gluten meal; 50% extruded soybeans, 50% corn gluten meal; and 25% extruded soybeans, 75% corn gluten meal. Diets were formulated to be 37.5% corn silage, 12.5% alfalfa cubes, and 50% concentrate (dry matter). Dietary crude protein was 15.7% of dry matter, and supplemental protein sources supplied 27% of total dietary protein. Diets were fed as total mixed rations and data were collected from 4 to 116 d postpartum.Milk and fat-corrected milk yields ranged from 31.0 to 34.3 and from 29.3 to 33.3 kg/d, respectively, and were greater for cows fed soybean meal than those cows fed 75 or 50% of their supplemental protein as extruded soybeans. Milk yield of cows consuming 75% of their supplemental protein from corn gluten meal was similar to all other treatments. Ruminal ammonia concentrations were lower in cows fed extruded soybeans and corn gluten meal compared with those fed soybean meal and ranged from 9.1 to 12.4mg/100 ml. Total volatile fatty acid concentration and pH did not differ among treatments. Combinations of extruded soybeans and corn gluten meal were not advantageous compared with soybean meal as a supplemental protein source for lactating cows in this experiment.     

Feeding Value of Dry Corn,Ensiled High Moisture Corn,and Propionic Acid Treated High Moisture Corn Fed with Hay or Haylage for Lactating Dairy Cows

Trial 1. Fifty lactating Holstein and Brown Swiss cows were assigned to six groups in a 3 × 2 factorial design and fed one of six diets for 16 wk: (1) dry corn + hay, (2) dry corn + haylage, (3) ensiled high moisture corn + hay, (4) ensiled high moisture corn + haylage, (5) propionic acid treated corn + hay, and (6) propionic acid treated corn + haylage. Quantities equal in dry matter of dry corn, ensiled corn, and acid treated corn were offered in the ratio of 1 kg concentrate (corn and supplement) for each 2.75 kg milk produced. Forage was fed free choice. Means adjusted by covariance for cows fed diets 1 to 6 averaged: dry matter intake (kg/day), 16.7, 20.0, 17.4, 20.6, 17.1, 20.0; 4% fat-corrected milk (kg/day), 21.8, 21.1, 22.6, 23.5, 22.4, 23.4; milk fat percent, 3.54, 3.45, 3.63, 3.53, 3.62, 3.80; and acetate to propionate ratio 3.53, 3.85, 3.73, 3.66, 3.13, 3.32. Cows fed ensiled corn and acid treated corn produced more 4% fat-corrected milk than did cows fed dry corn. The molar percent acetate to propionate ratio in rumen fluid of cows fed acid treated corn was lower than for cows fed dry corn or ensiled corn.Trial 2. Dry corn or propionic acid treated corn was fed to 12 cows in combination with a supplement, 4.54 kg of hay, and ad libitum haylage. Means adjusted by covariance for cows fed dry corn and acid treated corn averaged: dry matter intake (kg/day), 18.2 and 17.7; 4% fat-corrected milk (kg/day), 20.6 and 20.1; and total digestible nutrients (%) 63.7 and 58.7.Any of these methods are acceptable for storing corn, and feeding this corn in properly supplemented diets will yield acceptable lactation performance.     

Persistence of chlorpyrifos-methyl in corn silage and effects of feeding dairy cows the treated silage

Corn was sprayed in the field at dent stage of maturity with chlorpyrifos-methyl [O, O,-dimethyl O-(3, 5, 6-trichloro-2-pyridyl) phosphorothioate] at .56, 1.12, and 2.24 kg per hectare, ensiled 1 day later, and methodology for detection of residues was developed. Losses of total residues (chlorpyrifos-methyl and its pyridinol hydrolysis product) through 83 days of ensiling were equivalent to 55, 71, and 76% of that applied. Beginning 83 days post ensiling, control and treated silages were fed to 16 cows, 4 per treatment, for 42 days during which chlorpyrifos-methyl averaged .35, .87, and 1.85 ppm, and was stable. The pyridinol averaged .44, .79, and 1.75 ppm but continued to decline and during the last week of feeding averaged only 32% of that in silage fed the 1st wk. Residue intakes amounted to .009, .022, and .054 mg chlorpyrifos-methyl and .012, .020, and .051 mg of pyridinolk/g body weight and failed to affect silage intake, milk production, blood cholinesterase activity, or body weight gains. Traces of chlorpyrifos-methyl (.003 ppm or less) were only in milk from cows on the 2.24 kg treatment. Milk from all cows fed treated silage contained traces of the pyridinol (.011 ppm or less). No trace of the O-analog of chlorpyrifos-methyl was in any sample, and all milk, urine, and feces were free of residues within 1 wk after the cows were withdrawn from treated silage.     

By-Product Feeds for Lactating Dairy Cows: Effects of Cottonseed Hulls,Sunflower Hulls,Corrugated Paper,Peanut Hulls,Sugarcane Bagasse,and Whole Cottonseed with Additives of Fat,Sodium Bicarbonate,and Aspergillus oryzae Product on Milk Production

In Experiment 1, Holstein cows (32) fed diets in three 28-day periods were used to evaluate a 3 × 2 × 2 factorial arrangement of fiber sources (sunflower hulls, pelleted cottonseed hulls, and pelleted undelinted cottonseed hulls at 35% of dry matter), fat (0 or 2.5%). and sodium bicarbonate (0 or 1.0%). Sixteen cows also received Aspergillus oryzae product (56.7 g/day) continuously. Sunflower hulls decreased daily intake (19.4 versus 25.1 kg), milk (23.3 versus 26.5 kg), milk protein (2.85 versus 2.95%), and body weight change (?.08 versus .90 kg), but milk fat percent was higher (3.54 versus 3.32%). Sunflower hulls depressed digestibility of dry matter, organic matter, and acid detergent fiber. Added fat reduced milk fat and protein percents. Experiment 2 evaluated fiber sources (20% ground corrugated cardboard boxes, combination of 10% cardboard and 10% peanut hulls, or 30% cottonseed hulls), animal fat (0 or 2.5%), sodium bicarbonate (0 or .75%), and condensed molasses solubles by-product from rum distilling (0 or 10%). Corrugated boxes effected lowest intake (18.0 kg/day), cottonseed hulls highest intake (23.5 kg/day), and combination intermediate (20.2 kg/day). Added fat depressed fat percent. Condensed molasses solubles lowered milk yield but increased milk fat percent (3.76 versus 3.30), molar percent of acetic acid, and ratio of acetic to propionic. In two other experiments whole cottonseed (12.5 or 15% of dry matter) with corn silage, pelleted steam pressure treated sugarcane bagasse, or cottonseed hulls increased milk yield but decreased milk fat percent, especially with pelleted bagasse.