Blood responses of calves fed milk substitutes containing hydrolyzed fish protein and lime-treated corn flour

Two experiments involving 3- to 5-d-old dairy calves were carried out. In Experiment 1, lime-treated corn flour (Nixtamal) supplied 50 to 100% of carbohydrates in a milk substitute based on sodium caseinate, lard, and cerelose. In Experiment 2, partially hydrolyzed fish protein concentrate replaced 50% of 67% of proteins in milk substitutes based on skim milk powder, lard, and 35% Nixtamal. Increasing the proportion of carbohydrates supplied by Nixtamal was associated with a linear decrease of postprandial serum glucose and insulin. Postprandial fluctuations in blood glucose were less in calves fed Nixtamal than in controls. Nixtamal probably was trapped within the casein clot in the abomasum, leading to delayed rate of passage of Nixtamal carbohydrates into the intestine. Replacing skim milk protein with hydrolyzed fish protein in diets containing Nixtamal had no effect on blood glucose or insulin but elevated free essential amino acids, which promoted glucagon secretion. More uniform concentrations of blood essential amino acids and glucose were related to lower blood urea at 54 d in calves fed diets based on hydrolyzed fish protein and Nixtamal, than that of control calves. It is suggested that more uniform postprandial blood glucose concentrations might reduce amino acid degradation for energy purposes and stimulate protein synthesis. Young dairy calves may adapt to milk substitutes based on Nixtamal and hydrolyzed fish protein despite changes in the concentration patterns of several blood components.     

Diet digestibility and growth of holstein calves fed acidified milk replacers containing soy protein concentrate

Three experiments were conducted to determine the effects of acidification of milk replacers containing soy protein concentrate on diet digestibility and growth of Holstein bull calves. In Experiment 1, six calves (6 wk old) were fed at 10% of BW/d either acidified milk replacer containing soy protein concentrate or untreated milk replacer containing soy protein concentrate. Replacers were reconstituted to 12.5% DM for 10-d adjustment and 4-d collection periods to determine digestibility and N balance. Digestibilities of DM, ether extract, and N were similar between treatments. Nitrogen retention and N retention as a percentage of that absorbed were higher for calves fed the acidified diet. In Experiment 2, 20 calves (1 wk old) were fed diets identical to those diets fed in Experiment 1 at 20% of BW/d for 4 wk. Calves were allowed to adjust to the diet for 5 d. Growth parameters were measured and amount of feed offered was adjusted weekly. Calves fed the untreated diet had higher daily weight gains, girth gains, height gains, and better feed utilization. In Experiment 3, 21 calves were fed either the aforementioned diets or a replacer based on milk proteins at 10% of BW/d (12.5% DM) for 4 wk. Growth parameters were measured and DM intakes were adjusted weekly. Growth and feed conversion were similar across diets. Replacers containing soy protein concentrate or large amounts of whey may need to be supplemented with additional methionine to maximize rate of gain.     

Effects of varying forage and concentrate carbohydrates on nutrient digestibilities and milk production by dairy cows.

Five Holstein cows with ruminal cannulas were used in a 5 x 5 Latin square design to determine the effect of replacing forage NDF with soyhull NDF and varying concentrations of nonstructural carbohydrates on nutrient digestion and milk production. Diets in which NDF percentage from forage (corn silage: alfalfa hay, 1:1) was 80 (control), 70, or 60 were formulated by substituting soyhulls for forage; total forage was 43.2, 36.7, and 31.1% of the diets, respectively, but total NDF was 31%. Nonstructural carbohydrates were formulated to be 47 (control), 35, or 25% by substituting soyhulls, roasted soybeans, and Ca soaps for concentrate. Ruminal acetate: propionate ratio decreased linearly when diets lower in forage NDF were fed, but it increased quadratically when dietary nonstructural carbohydrates were reduced. Apparent digestibility of OM increased quadratically, but NDF digestibility and lactation performance were unaffected when diets lower in forage NDF were fed. Digestibility of NDF increased linearly when nonstructural carbohydrates were reduced, perhaps because of greater digestibility of soyhull NDF and smaller negative associative effects. Fat from soybeans and Ca soaps was increased as nonstructural carbohydrates decreased. Added fat probably increased fatty acid digestibility and decreased milk protein percentage. Greater FCM production without correspondingly greater feed intake or BW loss increased feed efficiency as nonstructural carbohydrates decreased. In dairy rations containing soyhulls, 60% of dietary NDF from forage should maintain lactation performance, and decreasing nonstructural carbohydrates to 25 to 35% of feed DM, coupled with adding dietary fat, may decrease negative associative effects and improve efficiency of milk production.     

Enzymatic Hydrolysate fo Fish,Spray-Dried Fish Solubles,and Soybean Protein Concentrate in Milk Replacers for Calves,

Holstein calves (120) were fed milk replacers as the only nutrients from 4 to 46 days of age. All milk replacers contained 20% crude protein and differed in protein source: 1) 100% milk protein; 2) 67% milk protein, 33% soybean protein concentrate; 3) 67% milk protein, 33% enzymatic hydrolysate of fish; 4) 67% milk protein, 16.5% soybean protein concentrate, 16.5% enzymatic hydrolysate of fish; 5) 67% milk protein, 16.5% soybean protein concentrate, 16.5% spray-dried fish solubles; 6) 67% milk protein, 24.75% soybean protein concentrate, 8.25% spray-dried fish solubles.Substitution up to 33% of dietary protein with soybean protein concentrate or combinations of soybean, enzymatic hydrolysate of fish, or spray-dried fish solubles produced 14% lower weight gains than all milk protein, but 33% replacement with enzymatic hydrolysate of fish produced 27% lower weight gains. Feed consumed per kilogram of gain was least for all milk, most for 33% fish hydrolysate, and intermediate for other rations. Scour scores did not differ between diets.     

Nutritional effects of including different levels and sources of protein in milk replacers for calves

Two digestibility and nitrogen balance experiments were carried out with groups of young calves given high-fat milk replacers reconstituted with water and fed in liquid form. In the first experiment six different milk replacers with crude protein contents ranging from 12.7 up to 27.6% in the dry matter were compared, the differences in protein content being brought about by adjustments to the level of separated milk protein used in the replacers. The apparent digestibility of organic matter was very high on all the treatments and unaffected by level of protein. Although the crude protein fraction showed an increase in apparent digestibility with increase in level of protein, its true digestibility was estimated to be virtually 100% on all the treatments. Retention of nitrogen expressed as a percentage of total intake remained fairly constant for diets containing from 18.8 to 27.6% of crude protein and the weight of nitrogen retained increased with each successive increase in level of dietary protein. In the second experiment the effects of replacing half of the milk protein in a control milk replacer by different forms of animal protein were studied. The true digestibilities of the total dietary protein on the treatment containing only separated milk protein and on the other treatments containing partial substitution by dried delactosed whey, dried blood, white fish meal and meat meal were found to be 94.1, 90.9, 85.4, 91.1 and 86.6%, respectively. Their biological values were 74.7, 70.3, 69.1, 66.0 and 65.5%, respectively. A sixth treatment in which the meat meal was provided with an enzyme supplement did not effect any significant change in either digestibility or biological value. Retentions of nitrogen expressed as percentages of intake were significantly lower on all the treatments containing partial replacement of separated milk protein by the other sources of protein than on the control treatment.     

Effect of replacing alfalfa silage with high moisture corn on nutrient utilization and milk production

Twenty-four multiparous lactating Holstein cows were blocked by days in milk and assigned to treatment sequences in a replicated 4x4 Latin square with 21-d periods. The four diets, formulated from alfalfa silage plus a concentrate mix based on ground high moisture ear corn, contained [dry matter (DM) basis]: 1) 20% concentrate, 80% alfalfa silage (24% nonfiber carbohydrates; NFC), 2) 35% concentrate, 65% alfalfa silage (30% NFC), 3) 50% concentrate, 50% alfalfa silage (37% NFC), or 4) 65% concentrate, 35% alfalfa silage (43% NFC). Soybean meal and urea were added to make diets isonitrogenous with equal nonprotein N (43% of total N). Intake of DM and milk yield indicated that adaptation was complete within 7 d of changing the diets within the Latin square. There were linear increases in apparent digestibility of DM and organic matter, and a linear decrease in neutral detergent fiber (NDF) digestibility with increasing dietary NFC. Solutions of significant quadratic equations yielded estimated maxima for intake of DM, organic matter, digestible organic matter, and NDF at, respectively, 37, 38, 43, and 27% dietary NFC. There were linear increases in yields of milk, protein, lactose, and solids not fat with increasing dietary NFC. Feed efficiency (milk/DM intake) yielded a quadratic response with a minimum at 27% dietary NFC. Maxima for milk fat content, fat yield, and fat-corrected milk yield were estimated to occur at, respectively, 30, 34 and 38% dietary NFC. In this short-term trial, maximal DM intake and fat-corrected milk yield indicated that the optimum concentrate for cows fed high moisture ear corn plus alfalfa silage as the only forage was equivalent to 37 to 38% dietary NFC; however, yields of milk, protein and solids not fat were still increasing at 65% dietary concentrate (43% NFC).     

Effects of hydrolyzed spray dried red blood cells in milk replacer on calf intake, body weight gain, and efficiency

An alternative protein ingredient based on spray-dried, hydrolyzed red blood cells was evaluated in calf milk replacers. Two experiments were conducted to determine the value of the ingredient on intake, growth, and feed efficiency in dairy calves. In experiment 1, Holstein bull calves (n = 120) were fed calf milk replacer containing 0, 11, 22, or 43% of crude protein as spray dried hydrolyzed red blood cells. Calves were fed 454 g/d of experimental milk replacer reconstituted to 12% dry matter plus a conventional calf starter for 28 d. Body weight gain, intake of milk replacer and calf starter, feed efficiency, fecal scores, and days scouring were unaffected by source of protein. In experiment 2, Holstein calves (n = 69) at the University of Minnesota, Crookston and Waseca were fed milk replacer containing 0, 22, or 43% of crude protein as spray dried hydrolyzed red blood cells. Calves were fed 454 g/d of experimental milk replacer reconstituted to 12% dry matter plus a conventional calf starter containing 0 or 25% alfalfa meal for 35 d. No calves died during the study. Body weight gain, feed efficiency, intake of calf starter and milk replacer, fecal scores, and days scouring were unaffected by increasing hydrolyzed red blood cells in milk replacer. Similar performance of all calves indicated that spray dried hydrolyzed red blood cells can replace up to 43% of crude protein from whey protein concentrate without detrimental effects on animal performance.     

Soy protein concentrate and heated soy flours as protein sources in milk replacer for preruminant calves

Thirty-two male calves (8/treatment) in Trial 1 and 41 male and female calves (10 or 11/treatment) in Trial 2 were fed milk replacers containing 100% of the total protein from milk sources or 25% from milk and 75% from a soy product: soy protein concentrate; commercial heated (fully cooked) soy flour; or experimental soy flour for 6 wk. The experimental flour received moist heat sufficient to reduce trypsin inhibitor to 1 unit/mg. Calf performance improved with age on all diets. Growth, protein and dry matter digestibility, nitrogen retention, and morphology of the intestinal mucosa of calves on the all milk-protein diet were superior to those of calves on diets containing a soy product. All soy-fed groups had a humoral but no cell-mediated immune reaction to soy proteins. Soy protein concentrate and the experimental heated soy flour were superior to the commercial heated soy flour as protein sources for milk replacer.     

Blood amino acids and milk composition from cows fed soybean meal, fish meal, or both

Twelve multiparous Holstein cows at 48 +/- 8 d in milk were used in a 4 x 4 Latin square with 21-d periods to determine the effect on feed intake, milk yield, milk composition, and blood amino acids when soybean meal was replaced with fish meal. Fish meal substituted for soybean meal on an isonitrogenous basis at 0, 25, 50, and 100% of supplemental protein. Total mixed diets were (dry matter basis) 25% corn silage, 25% alfalfa hay, and 50% concentrate mix. Intake of dry matter (27.9, 27.8, 26.1, and 25.8 kg/d for diets 1 to 4, respectively) was similar for all diets. Milk yield (37.5, 37.8, 37.2, and 37.7 kg/d) was not affected by diets. Milk protein percentages (3.23, 3.24, 3.31, and 3.35) increased with 100% fish meal supplementation and tended to be higher, with 50% fish meal supplementation compared with 100% soybean meal diet. Milk fat percentages (3.18, 2.99, 3.04, and 2.87) and yields were lower with the 100% fish meal than with the 100% soybean meal diet. Molar proportions of ruminal volatile fatty acids and ammonia were not greatly affected by diet. Fish meal supplementation slightly improved Met status, as shown when blood amino acid data were evaluated. Both extraction efficiency and transfer efficiency of amino acids from the blood by the mammary gland indicated that Met, Lys, and Phe were the most limiting amino acids in all diets. Replacing as much as 50 or 100% of dietary soybean meal with fish meal may improve the amino acid balance and increase the protein content in milk; however, feeding 100% fish meal will likely decrease milk fat percentages.     

Effect of protein on nutrient digestion and milk production by Holstein cows

Four multiparious Holstein cows fitted with ruminal and duodenal cannulae were in a 4 X 4 Latin square experiment to assess effects of increasing dietary protein on ruminal blood and duodenal traits, milk production, and nutrient digestion. Protein percents of 13, 15, 17, and 19 dry matter were achieved by rolled barley replaced with 0, 12, 24, and 36% rapeseed (canola) meal in pelleted concentrate mixtures. Increasing dietary protein concentration increased ruminal ammonia nitrogen, urea nitrogen in blood serum, and concentration of duodenal total, nonammonia, and feed nitrogen. Highest microbial nitrogen concentration was in cows fed the 15% protein diet; ruminal ammonia nitrogen was 6 mg/100 ml at this percent of protein. Cows fed 13% protein lost body weight (.43 kg/day), whereas those at 15, 17, and 19% protein gained .59, .38, and .59 kg/day. Efficiency of conversion of feed protein to milk protein declined, but digestibility of dry matter, organic matter, and nitrogen was improved with increasing dietary protein. From the traits measured, 15% crude protein appeared to be optimum for cows producing an average of 28 kg milk per day.     

Evaluation by digestibility,growth and slaughter with young milk-fed calves of microbial cells as a source of protein

A comparison of two milk replacer diets, using Ayrshire bull calves, was undertaken. Calves were offered either a diet based on skim milk, fat and whey (diet CM) or one (diet DMC 10) in which 20% skim milk was replaced by equal quantities of dried microbial cells (DMC) and whey. The inclusion of DMC resulted in a reduction in energy digestibility but had little effect on the digestibility of nitrogen. The metabolisable energy (ME) value for diet DMC 10 was significantly lower than that for diet CM. Calves offered diet DMC 10 consumed more feed and grew faster than calves on diet CM. The gross efficiency of conversion of nutrients for growth was unaffected by treatment and the composition of the liveweight gains was similar on both diets. The efficiencies of tissue accretion were higher for the calves given diet DMC 10, particularly in relation to the efficiency of use of nitrogen for tissue gain.     

Lactation performance of dairy cows fed increasing concentrations of wheat dried distillers grains with solubles

In Western Canada, dried distillers grains with solubles (DDGS) is produced from mixtures of corn and wheat at variable ratios, and used as a source of dietary crude protein (CP) in diets of lactating dairy cows. The objective of this study was to determine the effect of increasing dietary allocation of wheat DDGS on dry matter intake, milk production, milk composition, feed efficiency, plasma metabolites, and ruminal fermentation of dairy cows in midlactation. Sixteen multiparous and 16 primiparous lactating Holstein cows were used in a replicated 4 × 4 Latin square design with 3-wk periods. Dietary treatments were a control diet containing canola meal as the primary protein source (CON) and diets containing increasing concentrations of wheat DDGS in place of corn DDGS (0, 50, and 100% of dietary DDGS allocation). The treatment protein sources supplied approximately 35% of dietary CP. Yields of milk, milk fat, lactose, and energy-corrected milk were greater for diets containing DDGS compared with the CON diet. Although cows fed the DDGS diets tended to have lower CP digestibility compared with those fed the CON diet, concentrations of ruminal ammonia nitrogen, plasma urea nitrogen, and milk urea nitrogen were higher, but milk protein concentration was lower for cows fed the DDGS diets. Although dry matter intake increased linearly as the dietary allocation of wheat DDGS increased, milk yield was not affected, thus decreasing feed efficiency linearly. Feeding increasing levels of wheat DDGS tended to decrease plasma glucose concentration linearly. Plasma Leu concentration decreased linearly and plasma Gln concentration increased linearly as dietary inclusion of wheat DDGS increased. Apparent total-tract digestibility of nutrients except for CP was not affected by dietary treatments. A mixture of wheat and corn DDGS seems to have similar feeding values to both DDGS sources and it can be used as an alternative protein source in diets for lactating dairy cows. However, replacing corn DDGS with wheat DDGS might decrease feed efficiency.     

Palm kernel meal as the major protein concentrate in the diets of pigs in the tropics

Three trials were carried out to determine the suitability of locally produced palm kernel meal (PKM) as the major protein concentrate in the diets of weaners, growers and fattening pigs in the tropics. Large White and Large White×Land-race cross barrows and gilts were used. These were individually fed at semi-restricted levels the various diets formulated to contain approximately 15, 12 and 16.5% crude protein for trials 1, 2 and 3 respectively, the PKM or other protein sources contributing at least 50% of the total dietary protein in all the diets. In trial 1, pigs on the PKM diet grew at a lower rate, had poorer feed: gain ratio and protein efficiency ratio and lower feed consumption than the pigs on other diets. Pigs on a fish meal diet (FM) had the best performance throughout. In trial 2, the same trends as for trial 1 were observed, except that pigs on the dried skimmed milk (DSM) diet performed better than those on all other diets. In trial 3, the pigs on the PKM diet supplemented with 10% groundnut cake or 15% DSM had slower growth rate and lower feed:gain ratio than the pigs on other diets containing lower quantities of PKM supplemented with fish meal (FM) or blood meal (BM).     

Corn grain and liquid feed as nonfiber carbohydrate sources in diets for lactating dairy cows

Interactions of sources and processing methods for nonstructural carbohydrates may affect the efficiency of animal production. Five rumen-cannulated cows in late lactation were placed in a 5 × 5 Latin square design and fed experimental diets for 2 wk. In the production trial, 54 cows were fed the experimental diets for 12 wk beginning at d 60 in milk. Diets contained 24% corn silage and 22% hay, averaging 20% alfalfa and 2% grass but being adjusted as needed to maintain dietary concentrations of 36% neutral detergent fiber. The control diet contained steam-flaked corn (SFC) and the other diets contained either finely (FGC; 0.8 mm) or coarsely ground corn (CGC; 1.9 mm), factorialized with or without 3.5% liquid feed (LF). The LF diets provided 1.03% of dietary dry matter as supplemental sugar. The FGC decreased rumen pH and concentration of NH₃N compared with CGC. The SFC and FGC tended to increase the molar percentage of ruminal propionate and decrease the acetate:propionate ratio. The LF increased molar percentage of ruminal butyrate with FGC but not CGC. The LF tended to decrease starch digestibility with the CGC but not with the FGC. As expected, the SFC and FGC increased total tract starch digestibility. The DMI and milk yield were similar among dietary treatments. Compared with ground corn diets, the SFC tended to decrease milk fat percentage; thus, 3.5% fat-corrected milk and feed efficiency were decreased with SFC. The LF decreased milk protein percentage but had no effect on milk protein yield. The SFC compared with dry ground corn decreased the concentration of milk urea nitrogen. Sugar supplementation using LF appeared to be more beneficial with FGC than CGC. Increasing the surface area by finely grinding corn is important for starch digestibility and optimal utilization of nutrients.     

Relationships between milk urea concentrations and nutritional management, production, and economic variables in Ontario dairy herds

The objectives of this study were to describe the relationships between milk urea concentrations and nutritional management, production, and economic variables in commercial dairy herds. Dairy Herd Improvement (DHI) test-day milk urea data, production data, and information on ration nutrient composition and feeding management programs were collected over a 13-mo period from 53 commercial Ontario dairy herds. Economic variables included gross milk revenue, feed costs, and income over feed costs. Herd mean milk urea concentrations had a positive relationship with dietary levels of crude protein (CP), rumen degradable protein (RDP), and rumen undegradable protein (RUP) and a negative relationship with dietary levels of nonfiber carbohydrates (NFC), forage:concentrate (F:C) ratio, NFC:CP ratio, and NFC:RDP ratio. These findings are consistent with experimental studies that used chemical methods of milk urea analysis. Herd mean milk urea concentration was not associated with feeding management (e.g., total mixed rations, component feeding, feeding frequency, or synchrony of forage and concentrate feeding). Herd mean milk urea was not associated with either mean milk yield or linear score. Herd mean milk urea had a positive relationship with feed costs per cow per day but was not associated with gross milk revenue per cow per day. Herds with a high mean milk urea concentration tended to have lower income over feed costs per cow per day. High herd mean milk urea concentrations were associated with higher feed costs per kilogram of milk fat but lower gross milk revenue and lower income over feed costs per kilogram of milk fat. The results of this study demonstrate that DHI milk urea measurements produced by an infrared test method offer a useful tool for monitoring the efficiency of nitrogen utilization in commercial dairy herds. The results also suggest that diets may be balanced to achieve greater efficiency of nitrogen utilization, lower milk urea concentrations, and lower feed costs, while still achieving high milk production. This may lead to improved income over feed costs.     

Effects of sodium bicarbonate with three ratios of hay crop silage to concentrate for dairy cows

Three ruminally cannulated Holstein cows were fed total mixed diets of hay crop silage and concentrate (30:70, 50:50, 70:30, 100:0) to evaluate effects of sodium bicarbonate supplements equivalent to 0, .4, and .7% of total ration dry matter (0, 68, and 114 g/d). Yields of milk, fat-corrected milk, fat, protein, and solids-not-fat, percentages of milk protein and solids-not-fat, and efficiency of production of fat-corrected milk declined with decreasing concentrate proportion. Buffer supplementation reduced milk fat percentage and milk yield was greater with 68 g/d sodium bicarbonate than with 114 g/d. Digestibilities of dry matter, organic matter, gross energy, cell solubles, and crude protein declined with decreasing proportion of concentrate while cellulose digestibility increased linearly. The proportion of dietary nitrogen transferred to milk decreased linearly with decreasing proportion of concentrate and sodium bicarbonate increased this transfer with the 70% concentrate diet. Sodium bicarbonate increased ruminal pH and acetate proportion while decreasing ammonia concentration. Acetate:propionate ratio was decreased by sodium bicarbonate addition to the 70% concentrate diet. High concentrate diets with hay crop silage may require higher amounts of buffers to influence production.     

Effect of wet or dry corn gluten feed on nutrient digestibility and milk yield and composition.

A 22-wk trial was conducted to determine variations in nutrient concentrations of wet and dry corn gluten feed and their effect on nutrient digestibility and milk yield and composition. Holstein cows (n = 48) were blocked at parturition by parity and assigned randomly within block to one of three diets. All cows were fed a control TMR containing corn silage, ground corn, and commercial concentrate plus 2.3 kg/d of alfalfa hay during the 2-wk adjustment period. Thereafter, control diet was fed as wet or dry corn gluten feed substituted for 27% of dietary DM supplied by the control diet. Each cow received TMR for ad libitum consumption. Variations in nutrient concentrations of corn gluten feed were observed throughout the trial. The coefficient of variation was highest for ADIN, and standard deviation was highest for NDF. Intake of CP and NDF and apparent digestibility of DM were greatest when wet or dry corn gluten feed was fed. No differences in DMI, milk yield, and percentages of milk protein, lactose, or SNF were observed, but milk fat percentage was lowest when dry corn gluten feed was fed. Results indicate that corn gluten feed can replace 27% of dietary DM without altering milk yield, but new deliveries should be sampled regularly and amounts fed adjusted to compensate for varying nutrient concentrations.     

Effects of feeding crude glycerin on performance and ruminal kinetics of lactating Holstein cows fed corn silage- or cottonseed hull-based, low-fiber diets

The objective was to determine whether crude glycerin could partially replace concentrate ingredients in corn silage- or cottonseed hull-based diets formulated to support minimal milk fat production without reducing milk production. Multiparous, lactating Holstein cows (n=24; 116 ± 13d in milk) were assigned to dietary treatments arranged in a 2 × 3 factorial design; namely, 2 dietary roughage sources (cottonseed hulls or corn silage) and 3 dietary concentrations of glycerin [0, 5, or 10% on a dry matter (DM) basis]. Four different cows received each dietary treatment in each of 3 periods such that each diet was evaluated using 12 cows. Crude glycerin, produced using soybean oil, contained 12% water, 5% oil, 6.8% sodium chloride, and 0.4% methanol. Glycerin partially replaced ground corn, corn gluten feed, and citrus pulp. Diets of minimum fiber concentrations were fed to lactating dairy cows and resulted in low concentrations of milk fat (averaging 3.12% for cows fed diets without glycerin). The effects of glycerin on cow performance and ruminal measurements were the same for both dietary roughage sources with the exception of feed efficiency. Replacing concentrate with crude glycerin at 5% of dietary DM increased DM intake without increasing milk yield. Concentration and yield of milk fat were reduced when glycerin was fed at 10% of dietary DM. This was accompanied by a 30% reduction in apparent total-tract digestion of dietary neutral detergent fiber. Crude glycerin affected the microbial population in the rumen as evidenced by increased molar proportions of propionic, butyric, and valeric acids and decreased molar proportions of acetic acid. Efficiency of N utilization was improved as evidenced by lower concentrations of blood urea nitrogen and ruminal ammonia-N. Cows fed cottonseed hull-based diets consumed 5.3 kg/d more DM but produced only 1.7 kg/d more milk, resulting in reduced efficiency. Increased production of ruminal microbial protein, molar proportion of propionic acid, and passage of ruminal fluid resulted from feeding the cottonseed hull- versus corn silage-based diets, although apparent digestibilities of DM and neutral detergent fiber were reduced. Replacing 5 and 10% of concentrate ingredients with crude glycerin improved efficiency of 4% fat-corrected milk production when corn silage-based diets were fed but decreased it when cottonseed hull-based diets were fed.     

Effects of extrusion of grain and feeding frequency on rumen fermentation, nutrient digestibility, and milk yield and composition in dairy cows.

The effect of corn extrusion and feeding frequency on ruminal and postruminal digestibility and milk yield was studied in cows fed a high concentrate diet. Four Israeli Holstein cows fitted with rumen and abomasal cannulas were used. The experiment was arranged as a 2 x 2 factorial design, with two diets and two feeding frequencies (two or four meals per day). One diet contained 40% ground corn. In the second diet, half of the ground corn was replaced with extruded corn. Feeding cows the extruded versus ground corn diet decreased ruminal ammonia N and plasma urea N concentrations, increased postruminal digestibility of nonstructural carbohydrates, reduced dry matter intake, decreased yield of milk and milk components, and increased efficiency of milk energy and milk protein synthesis. The inclusion of extruded corn in the diet did not affect ruminal volatile fatty acid. Increasing the feeding frequency reduced the diurnal variation in ruminal pH, ruminal ammonia, and plasma urea, and increased dry matter intake--considerably more in the cows fed ground versus extruded corn--and improved postruminal organic matter, nonstructural carbohydrate, and crude protein digestibility. Total tract digestibility of organic matter and crude protein and milk yield and composition were also increased when cows were fed four versus two meals. Concurrent with the feeding frequency and grain processing effect, an increase in rumen-undegradable protein flow was related to increased digestion of nonstructural carbohydrate postruminally (r = 0.54). We concluded that for cows fed high-starch diets more frequent meals are useful for improving postruminal digestibility and milk yield and composition.     

Maximal replacement of forage and concentrate with a new wet corn milling product for lactating dairy cows

Three experiments were conducted to determine the maximal amount of concentrate and forage that could be replaced with a new wet corn milling product. The corn milling product contained 23.1% crude protein, 9.9% ruminally undegradable protein, 13.7% acid detergent fiber, 40.3% neutral detergent fiber, and 2.6% ether extract (% of dry matter; DM). In experiment 1, 16 Holstein cows were assigned to one of four diets in a replicated 4 x 4 Latin square design with 28-d periods. The four diets contained 54.3% forage (alfalfa:corn silages, 1:1 DM basis) with the wet corn milling product replacing 0, 50, 75, or 100% of the concentrate portion (corn and soybean meal) of the diet (DM basis). The diets containing wet corn milling product resulted in 7.8% lower DM intake, equivalent milk production (28.5 kg/d), and 13.6% greater efficiency of 4% fat-corrected milk (FCM) production than the control diet. There was no effect of diet on ruminal pH. In experiment 2, 16 Holstein cows were assigned to one of four diets in a replicated 4 x 4 Latin square design with 28-d periods. The 100% concentrate replacement diet from experiment 1 was used as control diet. For the test diets, forage was replaced with 15, 30, or 45% of the corn milling product (DM basis). Efficiency of FCM production (1.16) was not affected by diet. Rumination time was reduced for the 30 and 45% forage replacement diets, but ruminal pH was unaffected. In experiment 3, 30 Holstein cows were assigned at parturition to either a control diet (no corn milling product) or a diet containing 40% corn milling feed in place of both forage and concentrate (optimal levels from experiments 1 and 2) for 9 wk. The diet containing corn milling feed resulted in 21% greater efficiency of FCM production than the control diet. These results indicate that a new feed product based on wet corn milling ingredients has the potential to effectively replace all of the concentrate and up to 45% of the forage in the diet for lactating dairy cows.