Infusion of butyrate affects plasma glucose, butyrate, and ß-hydroxybutyrate but not plasma insulin in lactating dairy cows.

The objective of this study was to investigate the effects on plasma metabolites and rumen traits when butyrate was infused into the rumen or abomasum of lactating cows. Jugular catheters were inserted into 5 ruminally fistulated Holstein cows [94.2 ± 26.3 DIM; 717 ± 45 kg of body weight (BW); mean ± SD] in a 5 × 5 Latin square with 3-d periods. Cows were infused for 24 h with 1 of 5 treatments: water (CON), 1 g/kg of BW of butyrate infused into either the abomasum (A1) or rumen (R1), or 2 g/kg of BW of butyrate infused into either the abomasum or rumen. Sodium butyrate was the source of butyrate and NaCl was added to the CON, A1, and R1 treatments to provide the same amount of sodium as supplied by the sodium butyrate treatment in the 2-g treatments. Plastisol flanges were inserted into the abomasum to allow infusion to the abomasum and peristaltic pumps provided continuous infusion at 9.3 mL/min for all treatments. The concentration of NaCl and sodium butyrate was varied in the infusate to provide the correct infusion amount. Rumen fluid samples were collected at -2, -1, 0, 1, 2, 3, 4, 6, 8, 12, 18, 24, 28, and 32 h relative to start of infusion. Serial blood samples were collected at -2, -1, 0, 0.5, 1, 2, 3, 4, 6, 8, 12, 18, 24, 26, 28, and 32 h relative to start of infusion. Compared with CON, infusing butyrate increased both plasma butyrate and plasma ß-hydroxybutyrate (BHB), whereas plasma glucose decreased. Increasing butyrate infusion from 1 to 2 g increased plasma butyrate, tended to decrease plasma glucose, and tended to increase plasma BHB. Compared with abomasal infusion, rumen infusion of butyrate increased rumen butyrate, did not affect plasma glucose, and tended to increase plasma BHB. Treatment had no effect on plasma insulin. Results demonstrated that site of infusion and amount of butyrate affected several plasma metabolites when butyrate was infused in lactating dairy cows over a period of 24 h.

Single-dose infusion of sodium butyrate, but not lactose, increases plasma ß-hydroxybutyrate and insulin in lactating dairy cows.

Several studies have identified beneficial effects of butyrate on rumen development and intestinal health in preruminants. These encouraging findings led to further investigations related to butyrate supplementation in the mature ruminant. However, the effects of elevated butyrate concentrations on rumen metabolism have not been investigated, and consequently the maximum tolerable dosage rate of butyrate has not been established. Therefore, the first objective of this work was to evaluate the effect of a short-term increase in rumen butyrate concentration on key metabolic indicators. The second objective was to evaluate the source of butyrate, either directly dosed in the rumen or indirectly supplied via lactose fermentation in the rumen. Jugular catheters were inserted into 4 ruminally fistulated Holstein cows in a 4×4 Latin square with 3-d periods. On d 1 of each period, 1h after feeding, cows were ruminally dosed with 1 of 4 treatments: (1) 2L of water (CON), (2) 3.5g/kg of body weight (BW) of lactose (LAC), (3) 1g/kg of BW of butyrate (1GB), or (4) 2g/kg of BW of butyrate (2GB). Sodium butyrate was the source of butyrate, and NaCl was added to CON (1.34g/kg of BW), LAC (1.34g/kg of BW), and 1GB (0.67g/kg of BW) to provide equal amounts of sodium as the 2GB treatment. Serial plasma and rumen fluid samples were collected during d 1 of each period. Rumen fluid pH was greater in cows given the 1GB and 2GB treatments compared with the cows given the LAC treatment. Cows administered the 1GB and 2GB treatments had greater rumen butyrate concentrations compared with LAC. Those cows also had greater plasma butyrate concentrations compared with cows given the LAC treatment. Plasma ß-hydroxybutyrate was greater and insulin tended to be greater for butyrate treatments compared with LAC. No difference in insulin was found between the 1GB and 2GB treatments. Based on plasma and rumen metabolites, singly infusing 3.5g/kg of BW of lactose into the rumen is not as effective at providing a source of butyrate as compared with singly infusing 1 or 2g/kg of BW of butyrate into the rumen. Additionally, rumen pH, rumen butyrate, plasma ß-hydroxybutyrate, glucose, and plasma butyrate were less affected in cows administered the 1GB treatment than in cows given the 2GB treatment. This finding suggests that singly dosing 1g/kg of BW of butyrate could serve as the maximum tolerable concentration for future research.

Inclusion of various amounts of steam-flaked soybeans in lactating dairy cattle diets.

Whereas most soybean feedstuffs have been extensively investigated for use in ruminant diets, a lack of information exists regarding steam-flaked soybeans (SFSB). This research evaluated various inclusion rates of SFSB in diets for lactating dairy cattle. Twelve multiparous Holstein cows (103 ± 39 d in milk) were used in a 4 × 4 Latin square experiment consisting of 28-d periods, 14 d for diet transitioning followed by a 14-d sampling period. Treatments were inclusion of SFSB at 0, 5, 10, and 15% of dietary dry matter (DM), replacing a mixture of soybean meal, soy hulls, calcium salts of fatty acids, and choice white grease. Animals were fed lactating dairy cow diets formulated to be isonitrogenous and isoenergetic, containing 60% of DM as forage and 40% of DM as concentrate. Dry matter intake (mean = 28.8 kg/d), milk production (42.2 kg/d), milk fat percentage (3.52%), and feed efficiency (1.43 kg of energy-corrected milk/kg of DM intake) were similar across all treatments. Milk protein (2.98%) and lactose (4.87%) were also unaffected by the amount of SFSB in the diet. Milk urea nitrogen concentration decreased linearly as the amount of SFSB in the diet increased. Unlike some other soybean supplements, feeding SFSB did not increase trans-11 C18:1 or cis-9,trans-11 conjugated linoleic acid, but instead resulted in increased cis-9,cis-12 C18:2 and α-C18:3. Body weights (752 kg) and body condition scores (3.17) were similar with all diets. This research demonstrated that SFSB can be substituted for soybean meal and commercial fat sources while maintaining milk and milk component production and decrease milk urea nitrogen concentration.

Feeding fat from distillers dried grains with solubles to dairy heifers: I. Effects on growth performance and total-tract digestibility of nutrients.

The objective of this study was to determine if increased dietary fat from dried distillers grains with solubles (DDGS) in diets of growing heifers affected dry matter intake, average daily gain (ADG), growth performance, and nutrient digestibility. Thirty-three Holstein heifers (133±18 d old) were used in a 24-wk randomized complete block design. Treatments were (1) control (CON) containing ground corn and soybean products, (2) low-fat (LFDG) containing low-fat, high-protein DDGS and ground corn, and (3) high-fat (HFDG) with traditional DDGS. All diets contained 39.8% grass hay, 24.8% corn silage, and 1.5% vitamins and minerals. The HFDG diet was formulated to contain 4.8% fat compared with 2.8% in the CON and LFDG diets, which were greater in nonfibrous carbohydrate. Diets had a net energy gain of 1.0Mcal/kg of dry matter and were limit-fed at 2.45% of body weight. Heifers were weighed every 2wk and rations were adjusted accordingly. Heart girth, hip and wither heights, body length, and body condition score were recorded every 2wk. Total-tract digestion of nutrients was evaluated during wk16 using fecal grab sampling and an external marker. No treatments by time interactions were found. Dry matter intakes, body weights, ADG, and gain-to-feed ratio were similar among treatments; however, ADG averaged 0.96kg/d among treatments, which is greater than recommended. All body frame measurements and body condition scores were similar among treatments. Total-tract digestibilities of dry matter and organic matter were not different among treatments. However, crude protein and neutral detergent fiber digestibility were increased in the HFDG diet compared with the CON and LFDG diets. These results demonstrate that using DDGS or low-fat DDGS with corn in growing heifer rations can maintain performance. Utilizing the fat in DDGS as a dietary energy source in replacement of starch from corn did not influence growth performance or negatively affect nutrient digestion.

Short communication: Feeding fat from distillers dried grains with solubles to dairy heifers: III. Effects on posttrial reproductive and lactation performance.

The objective of this research was to determine the subsequent effects on lactation and reproductive performance from feeding fat from distillers dried grains with solubles (DDGS) to growing dairy heifers. During the prepubertal growth phase, 33 Holstein heifers (133±18 d old) were used in a 24-wk randomized complete block design. Treatments included (1) a control diet (CON) containing ground corn and soybean products, 2) a diet with low-fat DDGS (LFDG), and (3) a higher-fat diet with traditional DDGS (HFDG). All diets contained 39.8% grass hay, 24.8% corn silage, and 1.5% vitamins and minerals. Previous results demonstrated that growth performance was maintained across treatments, but plasma cholesterol and fatty acids were greater and puberty may occur earlier in heifers fed HFDG. It was hypothesized that differences among treatments in metabolic profile and puberty may influence reproductive and first-lactation performance. Posttrial data on reproductive performance and milk production for the first 4 mo of lactation were collected for each heifer from dairy herd records. At 3wk prepartum and at calving, body weights, body condition scores, and body measurements were taken. No differences were observed among treatments for age at conception or age at calving. At calving, heifers fed the HFDG were shorter in withers height compared with heifers fed the other diets. Milk yields and components were similar or improved in heifers fed the distillers grains diets compared with heifers fed CON. Heifers fed LFDG had greater milk production and a tendency for greater milk protein yields compared with the heifers fed CON. Energy-corrected milk yields were similar among treatments. Feeding increased dietary fat from DDGS during the prepubertal growth phase did not negatively affect milk production, despite earlier attainment of puberty compared with other treatments. The overall ADG for all 3 treatments was 0.96kg/d during the prepubertal period, which is greater than recommended and may have compromised milk yield across treatments. Based on these findings, producers can feed either DDGS or LFDG with corn in replacement of soybean products and corn to prepubertal heifers and maintain or enhance subsequent reproductive and lactation performance. Dietary fat from DDGS can replace starch from corn as an energy source for prepubertal heifers without detriment to later performance.

Feeding fat from distillers dried grains with solubles to dairy heifers: II. Effects on metabolic profile.

The objective of this study was to determine if increased dietary fat from dried distillers grains with solubles (DDGS) in diets of growing heifers affected metabolic profile, plasma fatty acid profile, and reproductive maturation. Thirty-three Holstein heifers (133±18 d of age) were used in a 24-wk randomized complete block design with 3 treatment diets. Treatment diets were (1) control (CON) containing ground corn (15.9% of DM) and soybean products (17.9%), (2) low-fat (LFDG) containing low-fat DDGS (21.9%) and ground corn (11.9%), or (3) high-fat (HFDG) with traditional DDGS (33.8%). Diets were isonitrogenous and isocaloric, but the HFDG diet was formulated to contain 4.8% fat compared with 2.8% in the CON and LFDG diets. All 3 diets were limit-fed to 2.45% of body weight on a dry matter basis, and resulted in a mean average daily gain of 0.96kg/d across treatments. Every 4wk, jugular blood was collected for analysis of metabolites and metabolic hormones. During wk20 of the feeding period, blood samples were collected for analysis of plasma fatty acid profiles. When heifers weighed between 200 and 300kg of body weight, coccygeal blood samples were taken twice weekly for analysis of progesterone to determine if puberty had been reached. Plasma concentrations of nonesterified fatty acids were similar among treatments and consistent over the duration of the study. Plasma concentrations of ß-hydroxybutyrate, insulin, insulin-like growth factor-1, and leptin were similar among heifers fed each treatment diet, but increased over the duration of the feeding period. Serum concentrations of glucose tended to be less in heifers fed HFDG compared with heifers fed the CON diet. Glucose concentrations fluctuated throughout the feeding period, but no treatment by time interactions were noted. Plasma urea N concentrations were less in heifers fed LFDG compared with heifers fed HFDG and CON diets. The concentrations of plasma urea N increased over the duration of the feeding period, with no treatment by week interaction. Total plasma cholesterol was greater in heifers fed HFDG compared with the CON and LFDG diets, and a significant week effect and a week by treatment interaction were observed. Fatty acid profiles also differed among treatments based on the supply of fatty acids from the diet. Progesterone analysis indicated that heifers fed HFDG tended to be pubertal at a younger age than heifers on CON. These results demonstrate that dietary fat from DDGS can be used in high-plane of nutrition rations for growing heifers and maintain metabolic energy status compared with starch from corn, but alters the concentrations of different blood lipids.

Performance, bioenergetic status, and indicators of oxidative stress of environmentally heat-loaded Holstein cows in response to diets inducing milk fat depression.

Effects of grain type and dietary oil supplement on production performance, energy balance, metabolic heat production, and markers of liver function of heat-loaded lactating dairy cows were evaluated using 8 multiparous Holstein cows (77.0d in milk) in a duplicated 4×4 Latin square design with a 2×2 factorial arrangement of treatments. Experimental diets contained either ground barley or ground corn supplemented with either fish oil or soybean oil at 2% of dietary dry matter. Mean daily maximum temperature, minimum relative humidity, and maximum temperature-humidity index were 35.3°C, 11.3%, and 77.0, respectively. Dietary treatment did not affect rectal temperature (38.9°C), but respiration rate tended to decrease in cows fed fish oil versus soybean oil. Dry matter intake decreased for the fish oil-supplemented diets (21.1 vs. 24.3kg/d), which was negatively correlated with plasma concentrations of alkaline phosphatase (r=-0.45; n=32) and malondialdehyde (r=-0.26; n=32). Actual milk yield (41.9kg/d) and energy-corrected milk yield (36.6kg/d) were not affected by grain type, whereas feeding fish oil decreased milk yield as compared with soybean oil (40.4 vs. 43.4kg/d). Milk fat depression occurred in all dietary treatments, especially when cows were fed fish oil because of the presence of polyunsaturated FA in the diets. trans-10 C18:1 was negatively correlated with milk fat yield (r=-0.38; n=32). Daily milk cis-9,trans-11 C18:2 secretion was 29.6% less in cows fed barley- versus corn-based diets but 31.8% greater in cows fed fish oil as compared with cows fed soybean oil. Because of a lower dry matter intake, metabolic heat production was decreased in cows fed fish oil relative to cows fed soybean oil. Although feeding fish oil versus soybean oil decreased net energy for both maintenance and lactation, net energy balance remained unchanged across treatments. In vivo plasma lipoperoxidation was greater in cows fed fish oil versus soybean oil, which substantiated increased susceptibility of plasma lipoperoxidation when cows were fed fish oil. Plasma concentration of malondialdehyde was positively correlated with plasma aspartate aminotransferase (r=0.38; n=32), which is an indicator of liver function in heat-loaded cows. Results suggest that in heat-loaded cows fed diets supplemented with soybean oil versus fish oil, biosynthesis in the mammary gland was prioritized over anabolism and oxidation in peripheral adipose and muscle tissues regardless of type of grain used.

Reciprocal combinations of barley and corn grains in oil-supplemented diets: feeding behavior and milk yield of lactating cows.

The effect of barley-based (BBD) or corn-based diets (CBD), or their equal blend (BCBD) on dry matter (DM) intake, feeding and chewing behavior, and production performance of lactating dairy cows was evaluated. Nine multiparous Holstein cows (75.6 ± 11.0 d in milk) were used in a triplicate 3 × 3 Latin square design with 21-d periods. Forage-to-concentrate ratio (40:60), forage neutral detergent fiber (20% of DM), total neutral detergent fiber (>29% of DM), and geometric mean particle size (4.3mm) were similar among treatments. Meal patterns, including meal size and intermeal interval, were not affected by the dietary treatments and DM intake (25.6 kg/d) was not different among treatments. Ether extract intake increased linearly with increasing amount of the corn grain in the diets. Due to similar feed intake, actual milk (48.6 kg/d), 4% fat-corrected milk (36.8 kg/d), and fat- and protein-corrected milk (38.1 kg/d) yields were not affected by treatments. Average milk protein percentage and yield were 2.83% and 1.37 kg/d, respectively, and were not different across treatments. Milk fat percentage increased linearly with increasing amount of corn grain in the diets and was greater in CBD relative to BCBD but not BBD (2.31, 2.28, and 2.57%, for BBD, BCBD, and CBD, respectively). However, milk fat yield tended to show a linear increase as the amount of corn grain included in the diets increased. Results indicated that changing diet fermentability by replacing barley grain for corn grain in oil-supplemented diets did not influence feeding patterns and thereby no changes in feed intake and milk yield occurred.

Ruminal degradability and intestinal digestibility of protein and amino acids in soybean and corn distillers grains products.

New fractionation and fermentation technologies in the ethanol industry have resulted in the production of different forms of distillers grains (DG). Such products are reduced-fat, high-protein, and "modified" wet feeds. Characterization of protein fractions of these co-products and other commonly used feedstuffs is important for the formulation of dairy cattle diets. In situ and in vitro techniques were conducted to compare crude protein (CP) availability in 4 DG products with commonly used soybean proteins. Soybean protein products included solvent-extracted soybean meal (SBM; 44% CP), expeller soybean meal (ESBM), and extruded soybeans (ES). The DG products were conventional distillers dried grains with solubles, reduced-fat distillers dried grains with solubles (RFDGS), high-protein distillers dried grains, and modified wet distillers grains with solubles (MWDGS). Nylon bags containing 5 g of each feed were incubated in the rumen of 3 cannulated lactating cows for 2, 4, 8, 16, 24, and 48 h. The rapidly degradable CP fraction varied from 8.1 to 37.2% for SBM and MWDGS, respectively. The slowly degradable CP fraction was greatest for SBM, ES, and high-protein distillers dried grains (88.0%+/-3.7), followed by ESBM, distillers dried grains with solubles, and RFDGS (76.8+/-4.1%). The MWDGS had the lowest slowly degradable CP fraction (61.1%). The rate of degradation of the slowly degradable CP fraction ranged from 11.8 for SBM to 2.7%/h for RFDGS. Rumen-undegradable protein varied widely (32.3 to 60.4%), with RFDGS having the greatest and SBM the lowest concentrations. Intestinal digestibility of rumen-undegradable protein (IDP) was estimated by pepsin-pancreatin digestion of ruminally preincubated (16 h) samples. The IDP was greatest for SBM, ESBM, and ES (97.7%+/-0.75), whereas IDP of DG products was 92.4%+/-0.87. Similarly, total digestible protein was greatest (99.0%) for soybean products, whereas DG products had a total digestible protein of 96.0%. Intestinal digestibility of most AA in DG products exceeded 92% and was slightly lower than for soybean products, except for Lys, where the digestibility was 84.6% for DG compared with 97.3% for soybean products. Absorbable Lys was lower for DG (7.0 g/kg of CP) compared with ESBM and ES (average of 23.8 g/kg of CP). Dried DG, ESBM, and ES provided more absorbable AA compared with SBM and MWDGS. These results suggest that the AA availability from DG products is comparable with that from soybean products.

Performance and amino acid utilization of early lactation dairy cows fed regular or reduced-fat dried distillers grains with solubles.

The objective of this study was to evaluate lactation response and AA utilization of early lactation cows fed 2 types of dried distillers grains with solubles (DG): regular (DDGS) or reduced-fat (RFDGS). Thirty-six Holstein cows 19.7+/-2.6 d in milk at the start of the experiment were used in a randomized complete block design for 14 wk including a 2-wk covariate period. Treatments consisted of the following diets: 1) control (CON) diet containing 0% DG; 2) diet containing 22% DDGS; and 3) diet containing 20% RFDGS. Distillers grains replaced soybean meal, expeller soybean meal, and soyhulls from the CON diet. Diets were formulated to be similar in crude protein, ether extract, neutral detergent fiber, and net energy for lactation concentrations. Dry matter intake (24.7 kg/d) and milk yield (39.3 kg/d) were similar for all diets. Milk fat and lactose percentages were unaffected by diets; however, protein percentage was greater for cows fed the DG diets compared with the CON diet. Consequently, milk protein yield was also greater for the DG diets compared with CON. Milk urea nitrogen decreased for cows fed DG diets and averaged 11.8, 10.9, and 10.1 mg/dL, respectively, for CON, DDGS, and RFDGS. Feed efficiency tended to be greater and N efficiency was greater for cows fed DG compared with CON. Body weight (711 kg), body weight change (+0.49 kg/d), and body condition score (3.36) were similar for all diets, but cows fed CON tended to gain more body condition (+0.14) than cows fed DG diets. Amino acid utilization was evaluated at the peak of milk production corresponding to wk 9 of lactation. Arterial Lys concentration was lower with DG diets (70.4, 58.6, and 55.8 microM/L). Cows fed DG had greater arterial Met concentration (21.3 microM) compared with CON (14.9 microM). Arterio-venous difference of Lys was similar across diets, whereas that of Met was greater for the DG diets compared with the CON diet (10.3 vs. 13.0 microM/L). Extraction efficiency of Lys by the mammary gland was greater for DG diets than for CON (76.1 vs. 65.4%). Mammary uptake of Lys (2.56 g/kg of milk) was similar for all diets, and the uptake of Met tended to increase in cows fed DG diets. Plasma glucose, triglyceride, and total cholesterol were unaffected by treatment; however, cows fed DG diets had lower beta-hydroxybutyrate and tended to have lower nonesterified fatty acid concentrations than cows fed the CON diet. Despite the apparent deficiency of Lys, milk protein percentage was increased in cows fed DG diets.

Saccharomyces cerevisiae fermentation product in dairy cow diets containing dried distillers grains plus solubles.

Sixteen multiparous Holstein cows (127+/-52 d in milk) were used in 4 replicated 4 x 4 Latin squares with 4-wk periods to evaluate interactions of dietary inclusion of a fermentation product of Saccharomyces cerevisiae (SC; XPC, Diamond V Mills, Cedar Rapids, IA) and dried distillers grains plus solubles (DDGS) on production of milk and milk components when fed diets containing approximately 30% dietary neutral detergent fiber with calculated forage neutral detergent fiber of 19.3% of diet dry matter (DM). Treatments were a 2 x 2 factorial arrangement with SC included at 0 or 14 g/d and DDGS at 0 or 20% of diet DM. Diets consisted of 27% corn silage, 18% alfalfa hay, and 55% concentrate mix on a DM basis. Diets not containing DDGS included additional corn, soybean meal, expeller soybean meal, soyhulls, and rumen inert fat to remain isocaloric and isonitrogenous with DDGS diets. Dry matter intake (26.0 kg/d) was similar for all diets. Milk production increased with the addition of SC to diets (43.6 vs. 42.0 kg/d for diets without SC) and decreased for cows fed diets containing DDGS (42.0 kg/d vs. 43.6 kg/d for diets not containing DDGS). Milk fat percentage (3.05 vs. 3.22% for DDGS and non-DDGS diets, respectively) and yield (1.27 vs. 1.41 kg/d) were decreased by the addition of DDGS but were not affected by the addition of SC. Concentrations of long-chain, polyunsaturated, trans-, and conjugated fatty acids in milk of cows fed DDGS were increased, but milk fatty acid profiles were not affected by SC. Milk true protein concentrations were similar for all diets; however, the addition of SC increased yield of true protein (1.32 vs. 1.27 kg/d). Concentrations of milk urea nitrogen increased when SC was included in the diet with DDGS. The DDGS decreased yields of energy-corrected milk (39.4 vs. 42.1 kg/d) and tended to decrease feed efficiency (1.53 vs. 1.61 kg of energy-corrected milk/kg of dry matter intake). Body weights and condition scores were not affected by treatments. Results suggest that diets containing minimal amounts of forage fiber and DDGS at 20% of diet DM will contribute to decreased milk production and milk fat depression. The addition of SC did improve milk and milk protein yields but did not prevent milk fat depression caused by DDGS. Production responses to SC were similar when cows were fed DDGS or non-DDGS diets.

Response of lactating dairy cows to high protein distillers grains or 3 other protein supplements.

This study compared high protein dried distillers grains (HPDDG) with soybean meal (SBM), canola meal (CM), and dried distillers grains with solubles (DDGS) as protein supplements in dairy diets. A lactation trial used 12 multiparous cows averaging 78 d in milk at the start of the experiment in a 4 x 4 Latin square design with 28-d periods. Weeks 1 and 2 of each period were used for adjustment and wk 3 and 4 for data collection. Each treatment diet consisted of 55% forage and one of the 4 protein supplements in a concentrate mix. Total mixed diets averaged 15.3% crude protein, with 38% of the protein from one of the 4 protein supplements. Dry matter intake (24.4 kg/d) and crude protein intake (3.57 kg/d) were similar for all 4 diets. Milk production (31.8 kg/d), protein yield (1.05 kg/d), fat yield (1.29 kg/d), and protein percentage (3.31) were similar for all 4 treatment diets. Milk fat percentage was lower when fed DDGS (3.78) than when fed SBM or HPDDG (4.21), but similar with CM (4.07). Feed efficiency (1.44kg of energy-corrected milk/kg of dry matter intake) and nitrogen efficiency (0.29) were not affected by diet. Total milk nitrogen and true milk protein were highest when fed the HPDDG diet. Molar proportions of acetate, propionate, and the acetate to propionate ratio in ruminal contents and ruminal ammonia concentrations were similar for all diets. Arterial and venous concentrations of total essential AA tended to be lower when fed CM, reflecting lower concentrations of His, Ile, Leu, and Val when fed the CM diet. Extraction efficiency of AA from blood by the mammary gland indicated that Met was the first limiting AA when fed the SBM diet, whereas Lys was first limiting for the other diets. Phenylalanine was third limiting with all diets. Feeding HPDDG was equally as effective as feeding SBM, CM, and regular distillers grains as a protein supplement for lactating cows.

Replacement of starch from corn with nonforage fiber from distillers grains and soyhulls in diets of lactating dairy cows.

Forty Holstein cows were used in a completely randomized design with a 2-wk covariate period followed by a 6-wk experimental period to evaluate incremental substitution of nonforage fiber provided by dried distillers grains with solubles (DDGS) and soyhulls (SH) for starch provided by corn in the diet. Diets provided decreasing concentrations of starch: 29% starch with 0% DDGS; 26% starch with 7% DDGS; 23% starch with 14% DDGS; and 20% starch with 21% DDGS. Diets contained 27% corn silage, 22% alfalfa hay, and 51% concentrate mix and were formulated to be 17% crude protein, 4.7% fat, and 23% neutral detergent fiber from forage. Total neutral detergent fiber increased as DDGS and SH were included in the diet. Soyhulls were included in a linear fashion along with DDGS to replace soybean meal and expeller soybean meal, thereby maintaining a similar crude protein content across diets. Dry matter intake decreased linearly; consequently, feed efficiency tended to increase linearly as starch was replaced by nonforage fiber. There was no effect of diet on milk production or milk fat and protein percentage or yield. Milk fatty acid profiles were similar across diets. Other response variables, including 4% fat-corrected milk, total solids, and milk urea nitrogen, were unaffected by dietary treatments. Ruminal volatile fatty acid concentration did not differ between diets. Concentrations of blood glucose and beta-hydroxybutyrate were similar across diets. Results from this research suggest that nonforage fiber from DDGS can partially substitute for starch from corn in dairy cow diets without affecting milk production and milk composition. Economic analysis of the diets showed that feeding DDGS and SH in substitution of corn was cost-effective. Results from this experiment indicate that DDGS and SH can replace corn as an energy source to decrease feed costs.

Lactation performance and amino acid utilization of cows fed increasing amounts of reduced-fat dried distillers grains with solubles.

The use of a solvent-extraction process that removes corn oil from distillers grains produces a reduced-fat co-product (RFDG). To determine the optimal concentration of RFDG in mid-lactation diets, 22 multiparous and 19 primiparous Holstein cows were used in a completely randomized design for 8 wk, including a 2-wk covariate period. The RFDG was included at 0, 10, 20, and 30% of the diet on a dry matter basis, replacing soybean feedstuffs. Increasing RFDG in diets had no effect on dry matter intake (23.1 kg/d) or milk production (35.0 kg/d). Milk fat percentage increased linearly from 3.18 to 3.72% as RFDG increased from 0 to 30% of the diet. Similarly, milk fat yield tended to increase linearly from 1.08 to 1.32 kg/d. Milk protein percentage (2.99, 3.06, 3.13, and 2.99% for diets with RFDG from 0 to 30%) responded quadratically, whereas protein yield was not affected by treatment. Milk urea N decreased linearly from 15.8 to 13.1mg/dL. The efficiency of N utilization for milk production was not affected by including RFDG (26.1%), whereas the efficiency of milk production (energy-corrected milk divided by dry matter intake) tended to increase linearly with increasing RFDG in the diet. Similarly, concentrations of plasma glucose increased linearly. Arterial Lys decreased linearly from 66.0 to 44.8 microM/L, whereas arterial Met increased linearly from 16.5 to 29.3 microM/L. Arteriovenous difference of Lys decreased linearly from 42.6 to 32.5 microM/L, whereas that of Met was unaffected. The extraction of Lys by the mammary gland increased linearly from 64.3 to 72.2%, whereas that of Met decreased linearly from 71.6 to 42.7%. Feeding up to 30% of RFDG in a mid-lactation diet supported lactation performance similarly to cows fed the soybean protein-based diet (0% RFDG).

Invited review: The use of distillers products in dairy cattle diets.

Distillers grains with solubles (DGS) is the major coproduct of ethanol production, usually made from corn, which is fed to dairy cattle. It is a good protein (crude protein, CP) source (>30% CP) high in ruminally undegradable protein (approximately 55% of CP) and is a good energy source (net energy for lactation of approximately 2.25 Mcal/kg of dry matter). The intermediate fat concentration (10% of dry matter) and readily digestible fiber (approximately 39% neutral detergent fiber) contribute to the high energy content in DGS. Performance was usually similar when animals were fed wet or dried products, although some research results tended to favor the wet products. Diets can contain DGS as partial replacement for both concentrates and forages, but DGS usually replaces concentrates. Adequate effective fiber was needed to avoid milk fat depression when DGS replaced forages in lactating cow diets. Nutritionally balanced diets can be formulated that contain 20% or more of the diet dry matter as DGS. Such diets supported similar or higher milk production compared with when cows were fed traditional feeds. Although DGS can constitute more than 30% of diet dry matter, gut fill may limit dry matter intake and production in diets with more than 20% wet DGS and that also contain other moist feeds. The fiber in DGS, which often replaces high-starch feeds, does not eliminate acidosis but minimizes its problems. Distillers solubles, which are often blended with distillers grains to provide DGS, can be fed separately as condensed corn distillers solubles. Other distillers coproducts besides DGS such as high-protein distillers grains, corn germ, corn bran, and low-fat distillers grains are becoming available.

Isolipidic additions of fat from corn germ, corn distillers grains, or corn oil in dairy cow diets.

Eight multiparous and 8 primiparous Holstein cows were used in a replicated 4 x 4 Latin square design with 4-wk periods to determine the effects on dairy cow performance of feeding corn germ (CG) compared with dried distillers grains with solubles (DDGS) or corn oil (CO). Four isolipidic dietary treatments were formulated: a control diet, a 14% corn germ diet (CGD), a 30% dry distillers grains with solubles diet (DGD), and a 2.5% corn oil diet (COD). All diets were formulated to contain 6.0% fat, with the fat in the control diet provided by a ruminally inert fat source. Dry matter intake was decreased by feeding the COD compared with the CGD; however, no difference in dry matter intake was observed among the control diet, the DGD, and the COD. Dietary treatments had no effect on milk yield, energy-corrected milk, or 4% fat-corrected milk. Feeding CG had no effect on milk fat percentage when compared with the control diet; however, milk fat percentage tended to decrease with DDGS and decreased with CO when compared with the CGD. Milk protein percentage decreased when cows were fed the COD compared with the control diet. Feeding CO tended to decrease milk fat yield compared with CG; however, dietary treatments had no effect on milk protein and lactose yield. Feed efficiency was not affected by dietary treatments and averaged 1.55 kg of energy-corrected milk/kg of dry matter intake. Feeding DDGS and CO increased the concentration of vaccenic and conjugated linoleic acid in milk fat. Concentrations of monounsaturated and polyunsaturated fatty acids in milk were increased in response to feeding the 3 corn coproducts. Fat from CG appears to be relatively protected in the rumen when compared with that from DDGS and CO and therefore will not affect the production of milk fat to the degree of the more available fat in DDGS and CO.

Canola meal replacing distillers grains with solubles for lactating dairy cows.

A study was conducted to determine the response to feeding diets containing canola meal (CM) as a protein supplement in place of all or portions of dried distillers grains with solubles (DDGS). Twelve lactating Holstein cows (4 primiparous and 8 multiparous) were fed in a 4 x 4 Latin square design over 4-wk periods. Data were collected wk 3 and 4 of each period. Diets were formulated in which CM was 100, 66, 33, and 0% of the supplemental protein replacing the protein from DDGS. All diets (averaged 15.1% crude protein and 4.5% ether extract) contained 55% forage and 45% concentrate, with the forage being 50% corn silage and 50% alfalfa hay. Dry matter intake (25.4 kg/d) was similar for all diets. Milk production (35.2, 35.8, 34.5, and 34.3 kg/d, respectively, for 100, 66, 33, and 0% CM) was similar for all diets, but tended to be greater with higher proportions of CM. Milk protein concentration (3.04%), fat concentration (3.92%), and fat yield (1.37 kg/d) were similar for all diets, whereas protein yield (1.08, 1.10, 1.05, and 1.03 kg/d, respectively, for 100, 66, 33, and 0% CM) tended to be greater with increasing amounts of CM in the diet. Feed efficiency (1.46 kg of energy-corrected milk/kg of dry matter intake) was similar for all diets. Lysine was the first limiting amino acid for milk protein synthesis when CM or DDGS were fed, whereas methionine was first limiting when the combination diets were fed. Concentrations of ammonia and volatile fatty acids in ruminal contents were similar for all diets. Canola meal is a suitable replacement for DDGS in dairy cow diets.

Ensiling characteristics of wet distillers grains mixed with soybean hulls and evaluation of the feeding value for growing Holstein heifers.

Two experiments were conducted to evaluate the fermentation characteristics of ensiled wet corn distillers grains with solubles (WDG) alone or mixed with soybean hulls (SH) and the ability of the mixture to maintain growth performance in dairy heifers. The first experiment was an ensiling study using laboratory silos. Ensiled blends were 100% WDG, 85% WDG with 15% SH, and 70% WDG with 30% SH on an as-fed basis. Silos were opened for analysis on d 0, 3, 7, and 21. The pH was less in the 100% WDG compared with other treatments (P < 0.01), but all treatments had a pH near 4. Lactic acid concentration was greater in 100% WDG compared with the blends of WDG and SH (P < 0.01). Acetic acid was not found in 100% WDG and increased over time in the 2 blends (P < 0.01). Other differences between blends, such as DM, CP, ammonia N, fiber, and fat, were reflective of the different concentrations of WDG and SH in the blends. In the second experiment, the 70% WDG and 30% SH (as-fed) blend was ensiled in a silo bag and then evaluated as a feed for growing dairy heifer diets. Twenty-four heifers were used in a randomized complete block design and assigned to be fed 1 of 3 diets: 1) control, 2) low inclusion of WDGSH, and 3) a high inclusion of WDGSH. All treatment diets consisted of 50% brome grass hay on a DM basis. The control diet had 50% of the diet (DM basis) as a grain mix, which was composed of corn, soybean meal, and minerals. The low WDGSH diet contained 24.4% of the blend and 25.6% grain mix. The high WDGSH diet contained 48.7% of the blend and 1.3% mineral mix. Average daily gain and most of the body growth measures were similar among treatments. However, DMI decreased linearly (P < 0.01) as the WDGSH blends were fed, resulting in improved (P = 0.02) G:F. Results from these experiments indicated that WDG can be effectively ensiled with SH and sustain adequate growth rate when fed to growing dairy heifers.

Evaluation of corn germ from ethanol production as an alternative fat source in dairy cow diets.

Sixteen multiparous cows (12 Holstein and 4 Brown Swiss, 132 +/- 20 d in milk) were used in a replicated 4 x 4 Latin square design with 4-wk periods to determine the effects of feeding corn germ on dairy cow performance. Diets were formulated with increasing concentrations of corn germ (Dakota Germ, Poet Nutrition, Sioux Falls, SD) at 0, 7, 14, and 21% of the diet dry matter (DM). All diets had a 55:45 forage to concentrate ratio, where forage was 55% corn silage and 45% alfalfa hay. Dietary fat increased from 4.8% in the control diet to 8.2% at the greatest inclusion level of corn germ. The addition of corn germ resulted in a quadratic response in DM intake with numerically greater intake at 14% of diet DM. Feeding corn germ at 7 and 14% of diet DM increased milk yield and energy-corrected milk as well as fat percentage and yield. Milk protein yield tended to decrease as the concentration of corn germ increased in the diet. Dietary treatments had no effect on feed efficiency, which averaged 1.40 kg of energy-corrected milk/kg of DMI. Increasing the dietary concentration of corn germ resulted in a linear increase in milk fat concentrations of monounsaturated and polyunsaturated fatty acids at the expense of saturated fatty acids. Milk fat concentration and yield of cis-9, trans-11 and trans-10, cis-12 conjugated linoleic acid were increased with increased dietary concentrations of corn germ. Although milk fat concentrations of both total trans-18:1 and cis-18:1 fatty acids increased linearly, a marked numeric increase in the concentration of trans-10 C18:1 was observed in milk from cows fed the 21% corn germ diet. A similar response was observed in plasma concentration of trans-10 C18:1. Feeding increasing concentrations of corn germ had no effect on plasma concentrations of glucose, triglyceride, or beta-hydroxybutyrate; however, the concentration of nonesterified fatty acids increased linearly, with plasma cholesterol concentration demonstrating a similar trend. Germ removed from corn grain before ethanol production provides an alternative source of fat for energy in lactating dairy cows when fed at 7 and 14% of diet DM. Our results suggest that fat from corn germ may be relatively protected with no adverse effect on DM intake, milk production, and milk composition when fed up to 14% of diet DM.