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PubMed1984

Comparative digestion, rumen fermentation and kinetics of forage diets by steers and wethers.

Four rumen fistulated wether and beef steers were used to evaluate differences in dry matter digestibility (DMD) between cattle and sheep. They were fed either perennial ryegrass or switchgrass hay at an ad libitum or restricted level for four experimental periods. Significant ruminant species X forage and ruminant species X level of intake (P less than .05) interactions were observed for digestible dry matter. The steers digested the switchgrass 7 percentage units greater than the wethers while ryegrass was digested equally. Digestibility differences between the steers and wethers were 6 percentage units at the ad libitum level of intake and 1 unit at the restricted level of intake. Crude protein digestibility tended to be greater (P less than .10) for sheep with a 7 unit difference for switchgrass and a 3 unit difference for ryegrass. The mean ruminal solids retention time of the digesta was approximately (P less than .01) 50% greater (26.0 vs 17.4 h) in cattle, with no difference in ruminal liquid dilution rate (LD) between animal species. Total ruminal volatile fatty acid concentration differed (P less than .01) with level of intake; however, no influence due to intake on the molar proportion of acetate (P greater than .10) or propionate (P greater than .10) was evident in spite of a difference (P less than .01) in LD. Rumen pH (P less than .05) and osmolality (P less than .01) were affected by both level of intake and forage, with the ryegrass and high level of intake decreasing pH and increasing osmolality.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1985

Monensin effects on digestibility, ruminal protein escape and microbial protein synthesis on high-fiber diets.

The influence of monensin level (0, 6.1, 12.2, 18.3 and 36.6 ppm) on diet fiber digestibility, microbial protein synthesis and ruminal escape of dietary protein was evaluated in two steer metabolism trials. A growth trial was conducted to study possible interactions of forage quality and monensin level. In metabolism trial 1, four ruminal-cannulated steers were assigned to four monensin levels in a 4 X 4 Latin square design to measure fiber digestibility, rate of passage and protein metabolism. In metabolism trial 2, five duodenal-cannulated steers were assigned to five monensin levels in a 5 X 5 Latin square design to measure fiber digestibility, bacterial N flow and plant N flow. In the two metabolism trials, the level of monensin influenced organic matter (OM) digestibility, neutral detergent fiber (NDF) digestibility and ruminal NDF digestibility quadratically, with the intermediate levels of monensin being superior either to the high level of monensin or no monensin. A quadratic increase in particulate disappearance rate (P = .09) and no effect (P = .95) on liquid disappearance were also observed in trial 1. In trial 1, monensin level quadratically decreased (P = .10) the bacterial protein concentration and increased (P = .02) the ratio of total N:diaminopimilic acid in whole rumen contents. In trial 2, no overall difference in duodenal N flow (P = .64) or flow of individual amino acids (P = .46) was observed. In the growth trial, no interaction of cornstalk quality and monensin was observed (P less than .38).(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1986

Nitrogen utilization and digestibility by growing steers and goats of diets that contain monensin and low crude protein.

Two digestion and metabolism experiments were conducted to determine effects of monensin in low-protein diets. Monensin supplementation (27 mg/kg of diet dry matter) of steers (303 kg) fed 8.7% crude protein increased (P less than .01) apparent N digestibility and N retention and decreased (P less than .01) percentage of N apparently absorbed lost in urine. Apparent digestibilities of dry matter, gross energy and acid detergent lignin were increased (P less than .05). Digestibilities of neutral detergent and acid detergent fibers were not affected by monensin. In growing wether goats (15 kg) fed 8.5% crude protein, monensin (23 mg/kg of diet dry matter) improved (P less than .01) apparent N digestibility and apparent N absorption. However, urinary N excretion also increased (P less than .05), resulting in no difference in N retention. Monensin did not affect digestibilities of dry matter or gross energy. Efficiency of feed conversion and average daily gain were improved with monensin supplementation of growing goats fed a low-protein, high-roughage diet. Monensin resulted in typical shift of acetate-to-propionate ratio in both experiments. Results suggest that improved N utilization may account for some benefits of feeding monensin.

Animals↗
PubMed1986

Comparison of the effects of three methods of harvesting and storing alfalfa on nutrient digestibility by lambs and feedlot performance of steers.

Two lamb digestion and three steer growth experiments were conducted to study the feeding value of alfalfa harvested as direct-cut silage (DCS) with grain added prior to ensiling or as low-moisture silage (LMS) or hay with grain added at feeding. In all experiments, alfalfa-grain mixtures contained approximately 50% alfalfa and 50% concentrate (dry matter [DM] basis). In Exp. 1, lambs fed DCS alone consumed less DM than lambs fed LMS or hay alone or any of the alfalfa-grain mixtures. Apparent digestibilities of DM and fiber components were higher (P less than .05) for DCS than for LMS or hay. Lambs that were fed LMS digested more (P less than .05) DM and fiber components than lambs fed hay. Addition of grain resulted in increased (P less than .05) DM digestibility and decreased (P less than .05) digestibilities of neutral detergent fiber and acid detergent fiber. In Exp. 2, growing steers (271 kg) fed DCS-grain had increased (P less than .05) weight gains compared with steers fed hay-grain. Steers fed any of the alfalfa-grain mixtures gained weight more rapidly (P less than .05) than steers fed corn silage (CS)-based diets. In a third experiment, finishing steers (283 kg) fed DCS-grain, LMS-grain, hay-grain or CS-based diets performed similarly (P greater than .05), although steers fed DCS-grain had higher (P less than .05) dressing percentages and yield grades than steers that were fed the other three diets and were fatter (P less than .05) than those fed LMS-grain or CS. In Exp. 4, lambs fed DCS-grain or LMS-grain had higher (P less than .05) apparent DM and organic matter digestibilities than lambs fed CS-based diets with similar forage:grain proportions. In Exp. 5, finishing steers (326 kg) fed DCS-grain gained similarly (P greater than .05) to steers fed LMS-grain or an 85% concentrate diet based on high-moisture corn. Steers fed CS diets had lower (P less than .05) gains and increased (P less than .05) feed per gain compared with steers fed DCS-grain, LMS-grain or high-moisture corn.

Animal Feed↗
PubMed1987

Effect of hay substitution on intake and digestibility of forage rape (brassica napus) fed to lambs.

Intake and digestibility trials were conducted with sheep to evaluate the effect of adding various levels of a typical fibrous grass forage (neutral detergent fiber, NDF = 68%) to a high quality, low fiber (NDF = 22%) brassica forage. Four forage rape:orchardgrass hay diets (0, 40, 70, 100% rape content on a dry matter basis) were fed to groups of six Polled-Dorset crossbred growing wether lambs (39.6 kg) individually housed in metabolism crates. After a 7-d ad libitum intake period, a 7-d digestibility trial was conducted at 90% of the observed ad libitum intake level. Digestible dry matter intake (DDMI) per unit metabolic body weight increased as rape in the diet was increased from 0 to 70%, with increases in both dry matter intake and dry matter digestibility (DMD). However, DDMI was similar for lambs fed the 70 and 100% rape diets, with DMI decreasing to the same relative extent as DMD increased. Digestibility of the cell wall fraction of the two intermediate diets (40% rape and 70% rape) was lower than predicted from component forage digestibilities. This observation suggests the existence of an associative effect similar to that often reported when forage and concentrates are fed in various ratios. Forage brassicas appear to be utilized in the ruminant in a manner more typically resembling a concentrate than a forage.

Animal Feed↗
PubMed1988

The digestibility of biotin in protein supplements and cereal grains for growing pigs.

Studies were carried out with six growing barrows fitted with a simple T-cannula 5 to 10 cm anterior to the ileo-cecal sphincter. In Exp. 1, the digestibility of biotin was determined in three cornstarch-based diets formulated to contain 16% CP by supplementation with soybean meal (SBM), meat and bone meal (MBM) and canola meal (CM). In Exp. 2 the digestibility of biotin was determined in three diets that contained 96.8% barley, corn or wheat. Experiments 1 and 2 were conducted according to a replicated 3 X 3 latin square design. In Exp. 3 pigs were fed a cornstarch-based diet supplemented with 12% vitamin-free casein to determine the amount of endogenous biotin. In Exp. 4 the digestibility of supplemental biotin was determined. There was a small amount of endogenous biotin in ileal digesta, 11 micrograms/kg DMI. Digestibilities of biotin determined at the distal ileum (apparent digestibilities corrected for endogenous biotin) were 55.4, 2.7 and 3.9% in SBM, MBM and CM, respectively, and 4.8, 4.0 and 21.6% in barley, corn and wheat, respectively. The digestibility of supplemental biotin was 93.5%. There was a large increase in the level of biotin between digesta collected from the distal ileum and in feces, ranging from 138 to 324 micrograms/kg DMI. With the exception of the CM diet, this increase exceeded dietary biotin intake. Biotin in many feedstuffs was not available in the small intestine.

Animals↗
PubMed1988

Breakdown of large particles in forage by simulated digestion and detrition.

To determine the importance of digestion and detrition (rubbing) in the rumen on the breakdown of large particles (LP) in the leaf and stem fractions of temperate and tropical forages, a study was made using a digestion-detrition simulator. Large-particle breakdown was measured in forage samples subjected to 48-h digestion or 48-h digestion plus detrition. Digestion caused a breakdown of 14% +/- 1.9% (means +/- SE) of the LP, and a further 8 +/- 1.9% were broken down by detrition. There was no difference in breakdown between temperate and tropical forages. The mean breakdown in vitro of LP of temperate forage was similar to that reported in vivo (21 vs 17%), but the breakdown of leaf fraction in vitro was twice that observed in vivo, possibly due to the greater breakdown in vivo of the LP during primary mastication. Both digestion and detrition cause a reduction in size of forage particles in vitro; this result supports conclusions drawn from in vivo studies.

Animal Feed↗
PubMed1988

Weekly digestibilities of diets supplemented with corn oil, lard or tallow by weanling swine.

Two experiments were conducted to evaluate supplementation of diets with 8% corn oil, lard or tallow. In Exp. 1, 36 barrows weaned at 21 d of age were used to evaluate the effects of these three diets on digestibilities of fat and dry matter and subsequent N retentions from wk 1 to 4 postweaning. In Exp. 2, 147 weanling pigs in six replicates were used to evaluate weekly growth and feed performance measurements when fed these same diets for a 4-wk postweaning period. A large quantity of fat was absorbed (P less than .01) during wk 1 postweaning by pigs fed the corn oil diet, with the quantity absorbed similar for the three sources of fat from wk 2 to 4. Diets with corn oil had a higher apparent fat digestibility than diets supplemented with lard or tallow during each week postweaning (P less than .05). Apparent digestibility of fat increased (P less than .01) for each fat source each week postweaning but appeared to reach a plateau by wk 3 postweaning. Differences in apparent digestibility of fat between fat sources narrowed from wk 1 to wk 4, with digestibility of corn oil increasing from 79 to 89% and of animal fat sources increasing from 67 to 84%. Apparent digestibility of dry matter tended (P less than .10) to be highest when corn oil was provided during the initial 2-wk postweaning period. Although N retention was highest during wk 1 postweaning when the corn oil was fed, this response was attributed to the higher feed intakes of pigs fed this diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1989

Intake of direct cut or wilted grass silage as related to chewing behavior, ruminal characteristics and site and extent of digestion by heifers.

Six nonpregnant Friesian heifers (516 kg avg BW) with ruminal and duodenal cannulas were used to examine intake of direct cut (DC) or wilted (W) grass silage in relation to chewing behavior, ruminal characteristics and site and extent of digestion. Dry matter content of the silages was 20.3% and 40.3%, and feed intake averaged 1.88% and 2.17% of BW (P less than .01), respectively. Mean ruminal osmolality was 291 mosm/liter for the DC and 318 mosm/liter for the W silage (P less than .05), with extreme values exceeding 350 mosm/liter for the W silage at 1 h to 2 h postfeeding. There was a shift from eating to ruminating on W silage associated with a longer duration of the average rumination bolus cycle (P less than .01). Duration of chewing time per kilogram of DM intake was 103.5 min and 91.7 min (P less than .05) for the DC and W silages, respectively. Fecal mean particle length was 2.2 times greater (P less than .01), accompanied by higher spread coefficients (P less than .001), for the W silage. No differences occurred between silages in ruminal digestibility of OM and NDF. In the total digestive tract, apparent digestibilities of OM and NDF were depressed after wilting grass prior to ensiling (P less than .01), but the proportion of digestible OM apparently digested in the rumen was .74 for both silages.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1989

Influence of soybean meal and sorghum grain supplementation on intake, digesta kinetics, ruminal fermentation, site and extent of digestion and microbial protein synthesis in beef steers grazing blue grama rangeland.

Six beef steers (British x Brahman) cannulated at the rumen, duodenum and ileum (avg wt 334 kg) and three mature steers (British x British) cannulated at the esophagus were used in a replicated 3 x 3 latin square design and fed no supplement (C), .5 kg soybean meal (SBM) or .5 kg steam-flaked sorghum grain (SFS).head-1.d-1 (DM basis) while grazing blue grama rangeland. Periods of the latin square included a minimum of 14 d for adaptation and 11 d for esophageal masticate collection and digesta sampling. In September, October and November, respectively, forage collected by esophageally cannulated steers averaged 74.5, 88.8 and 71.0% grasses; 2.06, 1.53 and 1.77% N and 68.3, (P greater than .10) by treatment, but total N intake was greater (P less than .05) for SBM vs C and SFS treatments. No differences (P greater than .10) were detected among treatments in OM, NDF, ADF and N digestibilities in the rumen, small intestine or hindgut, but total tract OM digestibility was greater (P less than .10) for SBM and SFS than for C, and total tract N digestibility was greater (P less than .10) for SBM than for C or SFS. Duodenal ammonia N flow was greater (P less than .05) when SBM was fed that when SFS and C were fed, but microbial N and non-ammonia, non-microbial N flows and microbial efficiency were not altered by treatment. Likewise, ileal N flow was not affected (P greater than .10) by treatment. Particulate passage rate, gastrointestinal mean retention time, forage in vitro OM disappearance and in situ rate of forage NDF digestion also were not affected (P greater than .10) by treatments. Ruminal fluid volume was greater (P less than .05) for SFS vs SBM and C treatments, but no differences were noted in fluid dilution rate. Ruminal fluid ammonia concentration was greater (P less than .05) when SBM was fed than when SFS and C were fed (13.5, 9.9 and 8.7 mg/dl, respectively), whereas pH and total VFA concentrations were not different (P greater than .10). Proportion of acetate in ruminal fluid was less (P less than .10) for SBM and SFS than for C. Small amounts of supplemental SBM and SFS had little effect on forage intake, ruminal fermentation and site of digestion but both increased total tract OM digestion in steers grazing blue grama rangeland.

Animal Feed↗
PubMed1989

Influence of phospholipids on ruminal fermentation in vitro and on nutrient digestion and serum lipids in sheep.

Phospholipid supplements were incubated in vitro or fed to sheep to determine how they affected ruminal fermentation, nutrient digestion and serum lipid concentration. In vitro, deoiled soybean lecithin added to hay increased (P less than .05) total VFA concentration but had no effect on fiber digestion in four of five trials. Purified phospholipid (synthetic phosphatidylethanolamine), however, had little effect on in vitro hay fermentation when tested at four levels (0, 10, 20 or 30 mg) in three separate trials. Deoiled soybean lecithin disappeared in vitro at two rates, 12.9 and .66%/h for the fast- and slow-degrading fractions, respectively. Compared with 2.4% corn oil supplements, 5.2% soybean lecithin added to sheep diets (56% concentrate) reduced (P less than .05) energy, fiber and nitrogen digestibilities. Crude lecithin reduced (P less than .05) energy digestibility more than deoiled lecithin. Both types of lecithin increased (P less than .05) serum nonesterified fatty acid concentrations but had no effect on serum glucose, cholesterol or triglyceride concentrations compared with the corn oil diet. In summary, phospholipids had different effects on ruminal fermentation, depending on their source. None had a beneficial effect on fiber digestion. Phospholipids are degraded in the rumen and inhibit digestion in a manner similar to that of the commercial fats and oils.

Animals↗
PubMed2002

Dietary soyabean oil depresses the apparent digestibility of fibre in trotters when substituted for an iso-energetic amount of corn starch or glucose.

The aim of the present study was to establish whether the inhibitory effect of fat feeding on fibre digestion has been underestimated due to the substitution of fat for corn starch. A high fat intake has been shown to lower total intestinal tract apparent digestibility of crude fibre in horses but, since fat was substituted for nonstructural carbohydrates, including starch, the specific effect of fat could not be ascertained. The possibility could not be excluded that starch also inhibits fibre digestibility, so that the fat effect observed earlier would have been underestimated. In this study, the intakes of iso-energetic amounts of soyabean oil, corn starch or glucose were compared as to fibre digestibility. Unlike starch, glucose is fully absorbed by the small intestine and, therefore, is not expected to influence fibre fermentation in the caecum and colon. Six trotters were fed rations high in soyabean oil (158 g/kg dry matter), corn starch (337 g/kg dry matter) or glucose (263 g/kg dry matter) according to a 3 x 3 Latin square design. Apparent crude fibre digestibility was similar for the rations with corn starch (mean +/- s.d., 70.7 +/- 3.06% of intake, n = 6) or glucose (71.0 +/- 1.90%), but was significantly depressed by fat feeding (56.5 +/- 7.65%). Similar observations were made for apparent digestibilities of neutral and acid detergent fibre and of cellulose. It was concluded that the addition of fat to the feed ration of horses has a specific inhibitory effect on fibre utilisation and, therefore, reduces the amount of energy provided by dietary fibre.

Animal Feed↗
PubMed1987

Starchy foods and fiber: reduced rate of digestion and improved carbohydrate metabolism.

The rate of the small intestine amylolytic digestion appears to be a major determinant of the glycemic response. Foods such as legumes appear to be digested less rapidly than many cereal foods although even amongst these large differences in rates of in vitro digestion exist. Studies of diabetes using high fibre, high legume diets have almost uniformly noted improvements in glycemic control and blood lipid profile. However, diets where changes in fibre content have been relatively small, but where the foods were selected on the basis of their slow rates of digestion and flatter glycemic response, have also produced similar beneficial effects. The reasons for the altered rates of digestion include fibre, food form, the nature of the starch, antinutrients etc. Through reducing the rate of digestion of starchy foods post prandially "slow release" starchy foods blunt many gut hormone responses, and prolong FFA and ketone body suppression. In addition increased starch losses to the colon may enhance production of SCFA. All these events may modify carbohydrate and lipid metabolism. Many foods which produce these effects are traditional starchy foods and so strengthen current recommendations of the diabetes association, heart foundations and cancer institutes to increase the use of starchy foods through reducing fat intake. Recognition of the nutritional value of these foods is however not new, but was well accepted in the ancient world and is still preserved in traditional cultures where freedom from many of the major non-infective Western diseases is a notable phenomenon.

Animals↗
PubMed2000

Feeding oleamide to lactating Jersey cows. 2. Effects on nutrient digestibility, plasma fatty acids, and hormones.

Six lactating Jersey cows were used in a 6 x 6 Latin square with 14-d periods to evaluate different ratios of canola oil and oleamide on nutrient digestibility, plasma fatty acids, and plasma hormones. The control diet contained no added fat. All other diets contained 3.5% added fat consisting of 0, 25, 50, 75, and 100% as oleamide and the remainder as canola oil. Data were collected during the final 4 d of each period. Dry matter intake was reduced by the addition of canola oil to the diet, and further reduced by replacing canola oil with oleamide. Milk yield was not affected by diet but increasing oleamide proportion in the fat supplement caused linear increases in cis-C18:1 and linear decreases in C4 to C16 fatty acids in milk. Adding canola oil reduced total tract digestibilities of fiber and fatty acids, but had no effect on the digestibilities of dry matter or protein. Replacing canola oil with oleamide increased protein digestibility linearly, and increased digestibility of fiber (quartic relationship) and fatty acids (quadratic relationship). Oleic acid concentration in plasma increased by adding canola oil to the diet, and was further increased by replacing canola oil with oleamide. Diet had no effect on plasma concentrations of insulin or IGF-I. Oleamide fed to Jersey cows in this study was highly digestible and had no deleterious effects on total tract digestility of fiber or protein. Increasing oleic acid concentration in plasma lipids while maintaining a constant level of added fat in the ration had no effect on circulating concentrations of insulin or IGF-I in Jerseys.

Animals↗
PubMed2000

Partial replacement of forage with nonforage fiber sources in lactating cow diets. II. Digestion and rumen function.

Replacement of forage with cereal byproducts may be a viable alternative for feeding dairy cows. The objective of this experiment was to evaluate total tract digestion and rumen fermentation profile when diets were formulated to contain low-forage neutral detergent fiber (NDF) (12.6% forage NDF, 18.8% total NDF), adequate NDF from forages (20% forage NDF, 24.4% total NDF) or low-forage NDF with high levels of NDF from cereal byproducts (12.7% forage NDF, 35.1% total NDF). Sodium bicarbonate (0.8% of dry matter) was factorialized over these diets. Total tract apparent digestibilities of organic matter (OM) and carbohydrates were determined in 73 Holsteins. Eight rumen-cannulated cows were used concurrently to evaluate rumen fermentation profile and in situ degradation of forages. Bicarbonate did not increase NDF or OM digestibility, but increased intake of digestible OM. Rumen fermentation parameters were determined by dietary alfalfa NDF content. Adding alfalfa NDF to the low-forage, high-starch diet increased in situ degradation of forage NDF more than adding byproduct NDF. However, increased ruminal forage NDF degradability was not reflected in greater total tract NDF digestibility. Replacement of dietary starch with NDF from byproducts decreased OM digestibility, but energy intake was similar across diets due to increased intake.

Animal Feed↗
PubMed2001

Digestion of ryegrass pasture in response to change in pH in continuous culture.

The ruminal pH of dairy cows fed high quality pasture is often below values recommended to optimize digestion. Four continuous culture fermenters were used to determine the pH required for the optimal digestion of pasture. High quality pasture was fermented at four controlled levels of pH (5.4, 5.8, 6.2, and 6.6) according to a 4 x 4 Latin square design. Automatic infusion of 5 M NaOH and 5 M HCl controlled pH to +/- 0.1. Digesta samples were collected during the last 3 d of each of the four 9-d experimental periods. Digestion and synthesis of microbial protein were largely insensitive to pH across a broad range of pH (5.8 to 6.6), but a large reduction in both occurred when pH was 5.4. The digestibility of pasture dry matter and synthesis of microbial protein were optimized at pH 6.35 and 6.13, respectively. The proportions of individual volatile fatty acids were not changed as pH increased. Digestion of high quality pasture in continuous culture was comparable to that predicted by the Cornell Net Carbohydrate and Protein System between pH 6.2 and 6.6. However, the model underpredicted organic matter and fiber digestibility between pH 5.4 and 5.8, compared with values obtained in continuous culture. This suggests that when ruminal pH is less than 6.2, the model may over-predict the production response to supplementation of high quality pasture with an effective fiber source.

Animal Feed↗
PubMed2002

Digestibility by dairy cows of monosaccharide constituents in total mixed rations containing citrus pulp.

Ten lactating cows were divided into two groups and individually fed ad libitum one of two experimental total mixed rations (TMR) as follows: 1) a TMR containing 20% corn grain and 10% dry citrus pulp (high corn); and 2) a TMR containing 21% citrus pulp and 9% corn grain (high citrus pulp). Both TMR also contained corn silage (28%), legume haylage (19.5%), extruded full fat soybeans (13.5 to 14%), soybean meal (6.5%), and minerals and vitamins. Voluntary dry matter intake of cows consuming the high corn ration tended to be higher than for cows in the high citrus pulp group (22.2 vs. 20.7 +/- 1.0 kg/cow per day, respectively). Digestibility of NDF was higher for the TMR with high citrus pulp compared with the TMR with higher corn. Across treatments, neutral detergent fiber (NDF) glucose was more digestible than NDF xylose and uronic acids and less digestible than NDF arabinose, galactose, and mannose. Digestibility of total neutral detergent soluble carbohydrates was also higher in the high citrus pulp group (86.8, high citrus pulp vs. 80.3 +/- 1.7%, high corn); with glucose and uronic acids accounting for most of that difference. Consequently, higher total carbohydrate digestibility was obtained in the TMR containing higher citrus pulp compared with the TMR with a higher percentage of corn (77.1 and 72.5 +/- 1.0%, respectively). Slightly lower carbohydrate intake in cows fed higher citrus pulp was compensated by higher digestibility of carbohydrates and protein. Thereby, partial replacement of corn by citrus pulp in TMR of high producing dairy cows improved feed efficiency.

Animal Feed↗
PubMed2002

Whole linted cottonseed as a forage substitute fed with ground or steam-flaked corn: digestibility and performance.

Six ruminally and duodenally cannulated Holstein cows were used in a 6 x 6 Latin square design. The objective was to evaluate any potential interactions in site of nutrient digestion when neutral detergent fiber (NDF) from cottonseed was incrementally substituted for forage NDF (FNDF) from alfalfa silage and when starch availability was varied by feeding ground (G) or steam-flaked (SF) corn. Iso-NDF diets were forage control with G corn (21% FNDF), 5% whole cottonseed (WCS) with G or SF corn (18% FNDF), 10% WCS with G or SF corn (15% FNDF), and 15% WCS with G corn (12% FNDF). Ruminal or total tract digestibilities of organic matter (OM) or nonstructural carbohydrate (NSC) were unaffected, but efficiency of microbial protein synthesis decreased as WCS increased. Ruminal NDF digestibility was not affected despite a linear decrease in pH, but postruminal NDF digestibility decreased with increasing WCS. Ruminal digestibilities of OM and NSC were higher for SF than G corn but did not affect efficiency of microbial N synthesis. Dry matter intake increased quadratically with increasing level of WCS but decreased when SF replaced G corn. Milk yield did not differ across treatments. Milk fat percentage was affected quadratically and milk protein increased linearly with increasing WCS. Milk fat percentage decreased but milk protein was not affected when SF replaced G corn. Lack of an interaction between corn source and level of WCS substitution suggests that WCS was equally effective in maintaining ruminal fermentation and digestibility in diets varying in ruminal starch availability.

Ammonia↗